Uncommon Cardiac Diseases - Fleisher: Anesthesia and Uncommon Diseases

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

CHAPTER 2 – Uncommon Cardiac Diseases

David L. Reich, MD,
Alexander Mittnacht, MD,
Joel A. Kaplan, MD

Cardiomyopathies

		General Classification
		Dilated Cardiomyopathy
		Hypertrophic Cardiomyopathy
		Restrictive Cardiomyopathy

Cardiac Tumors

		Benign Cardiac Tumors
		Malignant Cardiac Tumors
		Metastatic Tumors Involving the heart
		Cardiac Manifestations of Extracardiac Tumors
		Anesthetic Considerations

Ischemic Heart Disease

		Physiology of Coronary Artery Disease and Its Modification by Unusual Diseases
		Some Uncommon Causes of Ischemic Heart Disease
		Anesthetic Considerations

Pulmonary Hypertension and Cor Pulmonale

		Pulmonary Hypertension
		Cor Pulmonale
		Anesthetic Considerations

Constrictive Pericarditis and Cardiac Tamponade

		Normal Pericardial Function
		Constrictive Pericarditis
		Cardiac Tamponade
		Anesthetic Considerations

Uncommon Causes of Valvular Lesions

		Aortic Stenosis
		Pulmonic Stenosis
		Aortic Insufficiency
		Pulmonic Insufficiency
		Mitral Stenosis
		Tricuspid Stenosis
		Mitral Regurgitation
		Tricuspid Insufficiency
		Mitral Valve Prolapse
		Anesthetic Considerations

Uncommon Causes of Arrhythmias

		Idiopathic Long Q-T Syndrome
		Wolff-Parkinson-White and Lown-Ganong-Levine Syndromes

The Transplanted Heart

		The Denervated Heart
		Immunosuppressive Therapy
		Anesthetic Considerations

AIDS and the Heart

Anesthetic Considerations

Conclusion

The anesthetic management of uncommon cardiovascular disease states differs in no fundamental way from the management of the more familiar problems, since it rests on the same principles of management. These include (1) understanding the disease process and its manifestations in the patient; (2) a thorough understanding of anesthetic and adjuvant drugs, including their cardiovascular effects; (3) the proper use of monitoring; and (4) an understanding of the requirements of the surgical procedure.

Certainly the most common major cardiovascular diseases encountered are atherosclerotic coronary artery disease, degenerative valvular disease, and essentia hypertension. Experience with these disease states has made the anesthesiologist familiar with both the pathophysiology and the management of cardiac patients. Whereas the disease states discussed in this chapter are not often encountered, they can be reduced to familiar patterns of physiology and pathophysiology.

The principle of understanding a disease state and its manifestations in a patient remains the same whether the disease is common or uncommon. An evaluation of the degree of cardiovascular involvement using available clinical and laboratory information is necessary to make a rational assessment of the disease state in each individual patient. A thorough understanding of the cardiovascular effects of the anesthetic and adjuvant drugs to be employed allows the patient to be cared for using a rational anesthetic plan. Advances in cardiovascular pharmacology, anesthetic drugs, and new techniques of circulatory support have provided great flexibility in the management of the patient with impaired cardiovascular function.

The use of hemodynamic monitoring provides the best guide to intraoperative and postoperative treatment of patients with uncommon cardiovascular diseases. Monitoring is certainly no substitute for an understanding of physiology and pharmacology or clinical judgment; rather, the monitoring provides information that facilitates clinical decisions. Because the diseases to be discussed are rarely encountered, extensive knowledge of their pathophysiology, particularly in the anesthetic and surgical setting, is largely lacking, and monitoring helps bridge this gap. An understanding of the requirements of the surgical procedure and good communication with the surgeon are necessary in all operations to anticipate intraoperative problems, but especially in the diseases considered here.

This chapter does not provide an exhaustive list or consideration of all the uncommon diseases that affect the cardiovascular system, although it covers a wide range. No matter how bizarre a disease entity is, it can only affect the cardiovascular system in a limited number of ways. It can affect the myocardium, the coronary arteries, the conduction system, the pulmonary circulation, or valvular function, or it can impair cardiac filling or emptying. Subsections in this chapter follow this basic pattern. Each section is accompanied by tables of uncommon diseases that may produce a cardiomyopathy, coronary artery disease, pulmonary hypertension, or other cardiac disorder, along with various comments and caveats for each disease. This method of presentation provides a reasonable approach to the anesthetic management of uncommon diseases.

CARDIOMYOPATHIES

General Classification

Cardiomyopathies are defined as diseases of the myocardium that are associated with cardiac dysfunction. Cardiomyopathies can be classified in a number of ways. On an etiologic basis they are usually thought of as primary myocardial diseases, in which the basic disease locus is the myocardium itself, or secondary myocardial diseases, in which the myocardial pathology is associated with some systemic disorder. On a pathophysiologic basis, myocardial disease can be broken down into the following categories: dilated (congestive), hypertrophic, and restrictive cardiomyopathy ( Fig. 2-1 ). In 1995, the World Health Organization (WHO) International Society and Cardiology Task Force on the Definition and Classification of Cardiomyopathies developed the currently used clinical classification of cardiomyopathies. The WHO lists a functional classification of cardiomyopathies based on the underlying pathophysiology of cardiac dysfunction and specific cardiomyopathies in which the cardiomyopathy is associated with specific cardiac or systemic disorders ( Table 2-1 ).^[1] Unfortunately, there is often not a sharp division among the three categories, and a particular patient may have features suggestive of any or all of them. Dilated cardiomyopathies encompass both inflammatory and noninflammatory forms, and their most prominent clinical feature is myocardial failure manifested as ventricular dilatation, elevated filling pressures, and pulmonary edema. This, for example, is the usual response in cases of severe myocarditis. For the following discussion, the myocarditides will be included with inflammatory dilated cardiomyopathies. The obstructive form of myocardial diseases consists of hypertrophy of the myocardial muscle that may result in impaired filling and obstruction to ventricular outflow. Restrictive cardiomyopathies usually result from an infiltration of the myocardium by fibrous tissue or some other substance that decreases the compliance of the ventricle and impedes filling. They usually present a picture that mimics the physiology of constrictive pericarditis, often coupled with myocardial failure due to loss of muscle mass.



FIGURE 2-1 Illustration of the 50-degree left anterior oblique view of the heart in various cardiomyopathies at end systole and end diastole. (From Goldman MR, Boucher CA: Value of radionuclide imaging techniques in assessing cardiomyopathy. Am J Cardiol 1980;46:1232. Reproduced with permission.)

TABLE 2-1 -- The World Health Organization Classification of Cardiomyopathies

Rights were not granted to include this content in electronic media. Please refer to the printed book.

From Mason JW: Classification of Cardiomyopathies. In Fuster V, Alexander RW, O’Rourke RA (eds): Hurst's The Heart, 11th ed. New York, McGraw-Hill, 2004, p 1883. Reproduced with permission of the McGraw-Hill Companies.

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

Dilated Cardiomyopathy

Inflammatory (Myocarditis)

Dilated (congestive) cardiomyopathies exist in both inflammatory and noninflammatory forms (Tables 2-2 and 2-3 [2] [3]).^[2] The inflammatory variety, or myocarditis, is usually the result of infection.^{[3] [4]} Myocarditis presents as the clinical picture of fatigue, dyspnea, and palpitations, usually in the first weeks of the infection, progressing to overt congestive heart failure with cardiac dilatation, tachycardia, pulsus alternans, and pulmonary edema. Between 10% and 33% of patients with infectious heart diseases will have electrocardiographic (ECG) evidence of myocardial involvement. Mural thrombi often form in the ventricular cavity and may result in systemic or pulmonary emboli. Supraventricular and ventricular arrhythmias are common. Fortunately, complete recovery from infectious myocarditis is usually the case, but there are exceptions, such as myocarditis associated with diphtheria or Chagas' disease. Occasionally, acute myocarditis may even progress to a recurrent or chronic form of myocarditis, resulting ultimately in a restrictive type of cardiomyopathy secondary to fibrous replacement of the myocardium.^[5] In the bacterial varieties of myocarditis, isolated ECG changes or pericarditis are common and usually benign whereas congestive heart failure is unusual. Diphtheritic myocarditis is generally the worst form of bacterial myocardial involvement, because, in addition to inflammatory changes, its endotoxin is a competitive analog of cytochrome-B and can produce severe myocardial dysfunction.^[6] The conduction system is especially affected in diphtheria, producing either right or left bundle branch block, which is associated with a 50% mortality. When complete heart block supervenes, the mortality rate approaches 80% to 100%. Syphilis and leptospirosis represent two examples of myocardial infection by spirochetes.^[7] Tertiary syphilis is associated with multiple problems, including arrhythmias, conduction disturbances, and congestive heart failure.

TABLE 2-2 -- Inflammatory Cardiomyopathies (Dilated)

Disease Process	Mechanism	Associated Circulatory Problems	Miscellaneous
Bacterial		Arrhythmias, ST-T wave changes
Diphtherial	Endotoxin competitive analog of cytochrome B	Conduction system, especially BBB(ce:br/) Rare, valvular endocarditis	Temporary pacing often required
Typhoid	Inflammatory changes^[*] with fiber degeneration	Arrhythmias(ce:br/) Endarteritis, endocarditis, pericarditis, ventricular rupture
Scarlet fever β-Hemolytic strep	Inflammatory changes	Conduction disturbances and arrhythmias
Meningococcus	Inflammatory changes and endotoxin, generalized and coronary thrombosis	Disseminated intravascular coagulation(ce:br/) Peripheral circulatory collapse (Waterhouse-Friderichsen syndrome)
Staphylococcus	Sepsis, acute endocarditis
Brucellosis	Fiber degeneration and granuloma formation	Endocarditis, pericarditis
Tetanus	Inflammatory changes, cardiotoxin	Severe arrhythmias	Apnea
Melioidosis	Myocardial abscesses
Spirochetal leptospirosis	Focal hemorrhage and inflammatory changes	Severe arrhythmias(ce:br/) Endocarditis and pericarditis	Temporary pacing
Syphilis
Rickettsial		ECG changes, pericarditis
Endemic typhus	Inflammatory changes	Arrhythmias
Epidemic typhus	Symptoms secondary to vasculitis and hypertension	Vasculitis
Viral
HIV	Inflammatory changes	Systolic and diastolic dysfunction
	Myocarditis	Dilated cardiomyopathy and CHF
	Neoplastic infiltration	Pericardial effusion(ce:br/) Endocarditis(ce:br/) Pulmonary hypertension
Coxsackievirus B	Inflammatory changes	Constrictive pericarditis(ce:br/) AV-nodal arrhythmias
Echovirus	Inflammatory changes	Dysrhythmia
Mumps	Primary atypical pneumonia—associated Stokes-Adams attacks	Heart block
Influenza		Pericarditis
Infectious mononucleosis	Herpes simplex—associated with intractable shock
Viral hepatitis	Arbovirus—constrictive pericarditis is reported sequela
Rubella
Rubeola
Rabies
Varicella
Lymphocytic
Choriomeningitis
Psittacosis
Viral encephalitis
Cytomegalovirus
Variola
Herpes zoster
Mycoses	Usually obstructive symptoms
Cryptococcosis	Reported CHF
Blastomycosis
Actinomycosis		Valvular obstruction
Coccidiomycosis		Constrictive pericarditis
Protozoal
Trypanosomiasis (Chagas'disease—see text)	Inflammatory changes	Severe arrhythmia secondary to conduction system degeneration	Pacing often required
	Neurotoxin of Trypanosoma cruzi	Mitral and tricuspid insufficiency secondary to cardiac enlargement
Sleeping sickness	Inflammatory changes		Unusual manifestations of disease
Toxoplasmosis	Inflammatory changes	Cardiac tamponade
Leishmaniasis	Inflammatory changes		Unusual manifestations
Balantidiasis
Helminthic	Inflammatory changes
Trichinosis	Usually secondary to adult or ova infestation of myocardium or coronary insufficiency secondary to same	Arrhythmias
Schistosomiasis	Cor pulmonale—secondary pulmonary hypertension
Filariasis

BBB, bundle branch block; CHF, congestive heart failure; AV, atrioventricular.

^*	Inflammatory type usually has myofibrillar degeneration, inflammatory cell infiltration, edema.

TABLE 2-3 -- Noninflammatory Cardiomyopathies (Dilated)

Disease Process	Mechanism	Associated Circulatory Problems	Miscellaneous
Nutritional disorders
Beriberi	Thiamine deficiency	Peripheral AV shunting with low SVR
	Inflammatory changes	Usually high output failure with decreased SVR, but low output with normal SVR may occur
Kwashiorkor	Protein deprivation	Degeneration of conduction system
Metabolic disorders
Amyloidosis	Amyloid infiltration of myocardium	Associated with restrictive and obstructive forms of cardiomyopathy
		Valvular lesions
		Conduction abnormalities
Pompe's disease	α-Glucuronidase deficiency	Septal hypertrophy
Glycogen storage disease type II	Glycogen accumulation in cardiac muscle	Decreased compliance
Hurler's syndrome	Accumulation of glycoprotein in coronary tissue and parenchyma of heart	Mitral regurgitation
Hunter's syndrome	Same	Similar to but milder than Hurler's
Primary xanthomatosis	Xanthomatosis infiltration of myocardium	Aortic stenosis
		Advanced coronary artery disease
Uremia	Multiple metastatic coronary calcifications	Anemia	Most cardiac manifestations dramatically improve after dialysis
		Hypertension
	Hypertension	Conduction deficits
	Electrolyte imbalance	Pericarditis and cardiac tamponade
Fabry's disease	Abnormal glycolipid metabolism secondary to ceramide trihexosidase with glycolipid infiltration of myocardium	Hypertension
		Coronary artery disease
Hematologic diseases
Leukemia	Leukemic infiltration of myocardium	Arrhythmias	Usually resolves with successful therapy
		Pericarditis
Sickle cell	Intracoronary thrombosis with ischemic cardiomyopathy	Coronary artery disease
		Cor pulmonale
Neurologic disease
Duchenne's muscular dystrophy	Muscle fiber degeneration with fatty and fibrous replacement	Conduction defects possibly secondary to small vessel coronary artery disease	50% incidence of cardiac involvement
Friedreich's ataxia	Similar to Duchenne's with collagen replacement of degenerating myofibers	Conduction abnormalities
		? HOCM
Roussy-Lévy hereditary polyneuropathy	Similar to Friedreich's ataxia
Myotonia atrophica	Similar to above	Conduction abnormalities, possibly
		Stokes-Adams attacks
Chemical and toxic
Doxorubicin (see text)
Zidovudine (see text)
Ethyl alcohol (see text)	Myofibrillar degeneration secondary to direct toxic effect of ETOH and/or acetaldehyde
Beer drinker's cardiomyopathy	Probably secondary to the addition of cobalt sulfate to beer with myofibrillar dystrophy and edema	Cyanosis	Acute onset and rapid course
Cobalt intoxication	Similar to beer drinker's cardiomyopathy		CNS symptoms and aspiration pneumonitis are usually the predominant symptoms
Phosphorus	Myofibrillar degeneration secondary to direct toxic effect of phosphorus, which prevents amino acid incorporation into myocardial proteins		Relatively unresponsive to adrenergic agents
Fluoride	Direct myocardial toxin
	Severe hypocalcemia secondary to fluoride-binding of calcium ion
Lead	Secondary to nephropathic hypertension	Hypertension
	Direct toxin
Scorpion venom	Sympathetic stimulation with secondary myocardial changes		Adrenergic blockade probably indicated
Tick paralysis	?	Toxic myocarditis
Radiation	Hyalinization and fibrosis due to direct effect of x-radiation	Conduction abnormalities secondary to sclerosis of conduction system
		Coronary artery disease
		Constrictive myocarditis and pericarditis
Miscellaneous and systemic syndromes
Rejection cardiomyopathy	Lymphocytic infiltration and general rejection phenomena	Arrhythmias and conduction abnormalities	After heart transplantation
Senile cardiomyopathy	Unrelated to coronary artery disease
Rheumatoid arthritis	Rheumatoid nodular invasion	Mitral and aortic regurgitation
	Secondary to coronary arteritis	Coronary artery disease
		Constrictive pericarditis
Marie-Strümpell (ankylosing spondylitis)	Generalized degenerative changes	Aortic regurgitation
Cogan's syndrome (nonsyphilitic interstitial keratitis)	Fibrinoid necrosis of myocardium	Aortic regurgitation
		Coronary artery disease
Noonan's syndrome (male Turner's)	? (No detectable chromosome abnormality)	Pulmonary stenosis
		Obstructive and nonobstructive cardiomyopathy
Pseudoxanthoma elasticum (Grönblad-Strandberg)	Connective tissue disorder with myocardial infiltration and fibrosis	Valve abnormality
		Coronary artery disease
Trisomy 17–18	Diffuse fibrosis		? Viral etiology
Scleroderma of Buschke	Myocardial infiltration with acid mucopolysaccharides		Self-limited with good prognosis
Wegener's granulomatosis	Panarteritis and myocardial granuloma formation	Mitral stenosis (?)
		Cardiac tamponade
Periarteritis nodosa	Panarteritis	Conduction abnormalities
	Changes secondary to hypertension	Coronary artery disease
Cobalt intoxication	Similar to beer drinker's cardiomyopathy		CNS symptoms and aspiration pneumonitis are usually the predominant symptoms
Phosphorus	Myofibrillar degeneration secondary to direct toxic effect of phosphorus, which prevents amino acid incorporation into myocardial proteins		Relatively unresponsive to adrenergic agents
Fluoride	Direct myocardial toxin
	Severe hypocalcemia secondary to fluoride-binding of calcium ion
Lead	Secondary to nephropathic hypertension	Hypertension
	Direct toxin
Scorpion venom	Sympathetic stimulation with secondary myocardial changes		Adrenergic blockade probably indicated
Tick paralysis	?	Toxic myocarditis
Radiation	Hyalinization and fibrosis due to direct effect of x-radiation	Conduction abnormalities secondary to sclerosis of conduction system
		Coronary artery disease
		Constrictive myocarditis and pericarditis
Miscellaneous and systemic syndromes
Rejection cardiomyopathy	Lymphocytic infiltration and general rejection phenomena	Arrhythmias and conduction abnormalities	After heart transplantation
Senile cardiomyopathy	Unrelated to coronary artery disease
Rheumatoid arthritis	Rheumatoid nodular invasion	Mitral and aortic regurgitation
	Secondary to coronary arteritis	Coronary artery disease
		Constrictive pericarditis
Marie-Strümpell (ankylosing spondylitis)	Generalized degenerative changes	Aortic regurgitation
Cogan's syndrome (nonsyphilitic interstitial keratitis)	Fibrinoid necrosis of myocardium	Aortic regurgitation
		Coronary artery disease
Noonan's syndrome (male Turner's)	? (No detectable chromosome abnormality)	Pulmonary stenosis
		Obstructive and nonobstructive cardiomyopathy
Pseudoxanthoma elasticum (Grönblad-Strandberg)	Connective tissue disorder with myocardial infiltration and fibrosis	Valve abnormality
		Coronary artery disease
Trisomy 17–18	Diffuse fibrosis		? Viral etiology
Scleroderma of Buschke	Myocardial infiltration with acid mucopolysaccharides		Self-limited with good prognosis
Wegener's granulomatosis	Panarteritis and myocardial granuloma formation	Mitral stenosis (?)
		Cardiac tamponade
Periarteritis nodosa	Panarteritis	Conduction abnormalities
	Changes secondary to hypertension	Coronary artery disease
Postpartum cardiomyopathy
Neoplastic diseases
Primary mural cardiac tumors		Obstructive symptoms
Metastases—malignant (especially malignant melanoma)	Mechanical impairment of cardiac function
Sarcoidosis	Cor pulmonale secondary to pulmonary involvement	Cor pulmonale
		ECG abnormalities and conduction disturbances
	Sarcoid granuloma leading to ventricular aneurysms	Pericarditis
		Valvular obstruction

AV, atrioventricular; SVR, systemic vascular resistance; HOCM, hypertrophic obstructive cardiomyopathy; ETOH, ethanol; CNS, central nervous system.

Viral infections manifest themselves primarily with ECG abnormalities, including PR prolongation, QT prolongation, ST and T wave abnormalities, and arrhythmias. However, each viral disease produces slightly different ECG changes, with complete heart block being the most significant. Most of the viral diseases have the potential to progress to congestive heart failure if the viral infection is severe.^[8]Especially noteworthy in this regard is coxsackievirus B, which most commonly produces severe viral heart disease. Presenting as fulminating cardiac failure with severe atrioventricular (AV) nodal involvement and respiratory distress, viral myocarditis is common in nursery epidemics of coxsackievirus B infection. Recovery from coxsackievirus B myocarditis is usual, but the condition may have constrictive pericarditis as a sequela. Primary atypical pneumonia has the unusual feature of producing Stokes-Adams attacks secondary to AV node involvement.

Mycotic myocarditis has protean manifestations that depend on the extent of mycotic infiltration of the myocardium and may present as congestive heart failure, pericarditis, ECG abnormalities, or valvular obstruction.

Of the protozoal forms of myocarditis, Chagas' disease, or trypanosomiasis, is the most significant, and it is the most common cause of chronic congestive heart failure in South America. ECG changes of right bundle branch block and arrhythmias occur in 80% of patients. In addition to the typical inflammatory changes in the myocardium that produce chronic congestive failure, a direct neurotoxin from the infecting organism, Trypanosoma cruzi, produces degeneration of the conduction system, often causing severe ventricular arrhythmias and heart block with syncope. The onset of atrial fibrillation in these patients is often an ominous prognostic sign.^[9]

Helminthic myocardial involvement may produce congestive heart failure, but more commonly symptoms are secondary to infestation and obstruction of the coronary or pulmonary arteries by egg, larval, or adult forms of the worm. Trichinosis, for example, produces a myocarditis secondary to an inflammatory response to larvae in the myocardium, even though the larvae themselves disappear from the myocardium after the second week of infestation.

Noninflammatory

The noninflammatory variety of dilated cardiomyopathy also presents as the picture of myocardial failure, but in this case secondary to idiopathic, toxic, degenerative, or infiltrative processes in the myocardium (see Table 2-3 ).^{[10] [11]}

Alcoholic cardiomyopathy is a typical hypokinetic noninflammatory cardiomyopathy, associated with tachycardia and premature ventricular contractions, that progresses to left ventricular failure with incompetent mitral and tricuspid valves. This cardiomyopathy is probably due to a direct toxic effect of ethanol or its metabolite acetaldehyde, which releases and depletes cardiac norepinephrine.^[12]Alcohol may also affect excitation-contraction coupling at the subcellular level.^[13] In chronic alcoholics, acute ingestion of ethanol produces decreases in contractility, elevations in ventricular end-diastolic pressure, increases in systemic vascular resistance (SVR), and systemic hypertension.^{[14] [15] [16]}

Alcoholic cardiomyopathy is classified in three hemodynamic stages. In stage I, cardiac output, ventricular pressures, and left ventricular end-diastolic volume are normal but the ejection fraction is decreased. In stage II, cardiac output is normal although filling pressures and end-diastolic volume are increased and ejection fraction is decreased. In stage III, cardiac output is decreased, filling pressures and end-diastolic volume are increased, and ejection fraction is severely depressed. In general, all of the noninflammatory forms of dilated cardiomyopathy probably undergo a similar progression.

Doxorubicin (Adriamycin) is an antibiotic with broad-spectrum antineoplastic activities. However, the clinical usefulness of this drug is limited by its cardiotoxicity. Doxorubicin produces dose-related dilated cardiomyopathy. It has been suggested that doxorubicin disrupts myocardial mitochondrial calcium homeostasis. Patients treated with this drug usually have serial evaluations of left ventricular systolic function.^{[17] [18]} Dexrazoxane, a free-radical scavenger, may protect the heart from doxorubicin-associated damage.^[19]

Pathophysiology

The key hemodynamic features of the dilated cardiomyopathies are elevated filling pressures, failure of myocardial contractile strength, and a marked inverse relationship between afterload and stroke volume.

Both the inflammatory and noninflammatory forms of dilated cardiomyopathies present a picture identical to that of congestive heart failure produced by severe coronary artery disease, even to the extent that, in some conditions, the process that has produced the cardiomyopathy also involves the coronary arteries. The pathophysiologic considerations are familiar ones. As the ventricular muscle weakens, the ventricle dilates to take advantage of the increased force of contraction that results from increasing myocardial fiber length. As the ventricular radius increases, however, ventricular wall tension rises, increasing both the oxygen consumption of the myocardium and the total internal work of the muscle.

As the myocardium deteriorates further, the cardiac output falls, and a compensatory increase in sympathetic activity occurs to maintain organ perfusion and cardiac output. One feature of the failing myocardium is the loss of its ability to maintain stroke volume in the presence of increased afterload. Figure 2-2 shows that in the failing ventricle the stroke volume falls almost linearly with increases in afterload. The increased sympathetic outflow that accompanies left ventricular failure initiates a vicious cycle of increased resistance to forward flow, decreased stroke volume and cardiac output, and further sympathetic stimulation in an effort to maintain circulatory homeostasis.



FIGURE 2-2 Stroke volume (SV) as a function of afterload for a normal left ventricle, for a left ventricle with moderate dysfunction, and for a failing left ventricle.

Mitral regurgitation is common in severe dilated cardiomyopathies owing to stretching of the mitral annulus (Carpentier type 1) and distortion of the geometry of the chordae tendineae resulting in restriction of leaflet apposition (Carpentier type IIIb).^[20] The forward stroke volume improves with afterload reduction, even though there is no increase in ejection fraction. This suggests that reduction of mitral regurgitation is the mechanism of the improvement. Afterload reduction also decreases left ventricular filling pressure, which relieves pulmonary congestion and should preserve coronary perfusion pressure.^[21]

The clinical picture of the dilated cardiomyopathies falls into the two familiar categories of “forward” failure and “backward” failure. The features of “forward” failure, such as fatigue, hypotension, and oliguria, are due to decreases in cardiac output with reduced organ perfusion. Reduced perfusion of the kidneys results in activation of the renin-angiotensin-aldosterone system, which increases the effective circulating blood volume through sodium and water retention. “Backward” failure is related to the elevated filling pressures required by the failing ventricles. As the left ventricle dilates, “secondary” mitral regurgitation occurs. The manifestations of left-sided failure include orthopnea, paroxysmal nocturnal dyspnea, and pulmonary edema. The manifestations of right-sided failure include hepatomegaly, jugular venous distention, and peripheral edema.

Anesthetic Considerations

ECG monitoring is essential in the management of patients with dilated cardiomyopathies, particularly in those with myocarditis. Ventricular arrhythmias are common, and complete heart block, which can occur from these conditions, requires rapid diagnosis and treatment. The electrocardiogram is also useful in monitoring ischemic changes when coronary artery disease is associated with the cardiomyopathy, as in amyloidosis. Direct intra-arterial blood pressure monitoring during surgery provides continuous blood pressure information and a convenient route for obtaining arterial blood gases. Any dilated cardiomyopathy patient with a severely compromised myocardium who requires anesthesia and surgery should have central venous access for monitoring and vasoactive drug administration. Monitoring right-sided filling pressures is of equal importance in patients with pulmonary hypertension or cor pulmonale. The use of a pulmonary artery catheter (PAC) is much more controversial. The American Society of Anesthesiologists Task Force on Pulmonary Artery Catheterization has published practice guidelines for pulmonary artery catheterization.^[22] The indication for PAC placement is dependent on a combination of patient-, surgery-, and practice setting–related factors. Patients with severely decreased cardiac function from dilated cardiomyopathy have significant cardiovascular disease and are considered at increased or high risk. Because there was no evidence-based medicine to support outcome differences, recommendations for PAC monitoring were based on expert opinion at that time. Patients with dilated cardiomyopathy presenting for surgery who have an overall increased- or high-risk score should probably have hemodynamic parameters monitored with a PAC. In addition to measuring right- and left-sided filling pressures, a thermodilution pulmonary artery catheter may be used to obtain cardiac outputs and for the calculation of systemic and pulmonary vascular resistances, which allow for serial evaluation of the patient's hemodynamic status. PAC with fiberoptic oximetry, rapid-response thermistor catheters that calculate right ventricular ejection fraction, and pacing PAC are available. Pacing PAC and external pacemakers provide distinct advantages in managing the patient with myocarditis and associated heart block. Recent evidence seems to provide further support for clinicians who choose not to use PAC monitoring on the basis of no outcome differences between high-risk surgical patients who were cared for with and without PAC monitoring and goal-directed therapy.^[23]

Transesophageal echocardiography (TEE) provides useful data on filling, ventricular function, severity of mitral regurgitation, and the response of the impaired ventricle to anesthetic and surgical manipulations. Recently published guidelines indicate that hemodynamic decompensation is a class I indication for TEE monitoring.^[24] With the increased availability of TEE equipment and anesthesiologists trained in its use, this modality will become increasingly important in the perioperative management of patients with cardiomyopathies.

The avoidance of myocardial depression still remains the goal of anesthetic management for patients with dilated cardiomyopathy ( Table 2-4 ), although, paradoxically, β-adrenergic blockade has been associated with improved hemodynamics and improved survival in patients with dilated cardiomyopathy.^{[25] [26] [27] [28]} All of the potent volatile anesthetic agents are myocardial depressants, and, for this reason, high concentrations of these agents are probably best avoided in this group of patients. Low doses are usually well tolerated, however. An anesthetic based primarily on a combination of narcotics and sedative-hypnotics (with or without nitrous oxide) can be employed instead. For the patient with severely compromised myocardial function, the synthetic piperidine narcotics (fentanyl, sufentanil, remifentanil, and alfentanil) are useful, because myocardial contractility is not depressed. Chest wall rigidity associated with this technique is treated with muscle relaxants. Bradycardia associated with high-dose narcotic anesthesia may be prevented by the use of pancuronium for muscle relaxation, anticholinergic drugs, or pacing. Pancuronium, however, should be avoided in patients with impaired renal function, which is a common problem in cardiomyopathy patients. For peripheral or lower abdominal surgical procedures, the use of a regional anesthetic technique is a reasonable alternative, provided filling pressures are carefully controlled and the hemodynamic effects of the anesthetic are monitored. One problem is that regional anesthesia is frequently contraindicated because patients with cardiomyopathies are frequently treated with anticoagulant drugs to prevent embolization of mural thrombi that develop on hypokinetic ventricular wall segments. For shorter procedures, high-dose opioid anesthesia using remifentanil may prove to be advantageous because of the cardiovascular advantages of opioid anesthesia and its extremely short duration of action.

TABLE 2-4 -- Treatment Principles of Dilated Cardiomyopathies

Clinical Problem	Treatment	Relatively Contraindicated
↓ Preload	Volume replacement	Nodal rhythm
	Positional change	High spinal
↓ Heart rate	Atropine
	Pacemaker	Verapamil
↓ Contractility	Positive inotropes	Volatile anesthetics
	Digoxin
↑ Afterload	Vasodilators	Phenylephrine
		Light anesthesia

In planning anesthetic management for the patient with dilated cardiomyopathy, associated cardiovascular conditions, such as the presence of coronary artery disease, valvular abnormalities, outflow tract obstruction, and constrictive pericarditis should also be considered. Patients with congestive heart failure often require circulatory support intraoperatively and postoperatively. Inotropic drugs, such as dopamine or dobutamine, have been shown to be effective in low output states and produce modest changes in SVR at lower dosages. In severe failure, more potent drugs such as epinephrine may be required. Phosphodiesterase III inhibitors, such as milrinone, with inotropic and vasodilating properties may improve hemodynamic performance. As noted earlier, stroke volume is inversely related to afterload in the failing ventricle and the reduction of left ventricular afterload with vasodilating drugs such as nitroprusside and nesiritide is also effective in increasing cardiac output. In patients with myocarditis, especially of the viral variety, transvenous or external pacing may be required should heart block occur. Intra-aortic balloon counterpulsation and left ventricular assist devices are further options to be considered in the case of the severely compromised ventricle.

There is a definite increase in the incidence of supraventricular and ventricular arrhythmias in myocarditis and the dilated cardiomyopathies.^{[29] [30]} These arrhythmias often require extensive electrophysiologic workup and may be unresponsive to maximal medical therapy. Some patients will present for automatic internal cardioverter-defibrillator implantation. Originally, cardioverting pads were sewn to the epicardial surface via a median sternotomy and the device was implanted in the abdominal wall. The procedure has become markedly less invasive. Presently, the device is implanted in the subcutaneous tissue near the deltopectoral groove and transvenous electrodes are placed in the heart. Intraoperative attempts to elicit arrhythmias are necessary to test the device. Thus, proper ECG monitoring and access to a charged external cardioversion device are important details.

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathies usually result from asymmetrical hypertrophy of the basal ventricular septum and occur in either obstructive or nonobstructive forms ( Table 2-5 ). A dynamic pressure gradient in the left ventricular outflow tract (LVOT) is present in the obstructive forms.^{[31] [32] [33]} Other conditions can also produce the picture of an obstructive cardiomyopathy such as massive infiltration of the ventricular wall, as in Pompe's disease, where an accumulation of cardiac glycogen in the ventricular wall produces LVOT obstruction. In the following discussion the focus is on the obstructive form.

TABLE 2-5 -- Cardiomyopathies (Hypertrophic)

Disease Process	Mechanism	Associated Circulatory Problems
Idiopathic concentric hypertrophy	Symmetrical hypertrophy of left ventricle and outflow tract (usually nonobstructive)
Hypertrophic obstructive cardiomyopathy (IHSS, ASH)	(See text)
Systemic syndromes
Glycogen storage disease type II (Pompe's)	Glycogen infiltration of septal walls	Dilated cardiomyopathy
Noonan's syndrome	Left ventricular outflow obstruction	Coronary artery disease
Lentiginosis	Right and left AV-septal hypertrophy	Pulmonary stenosis

IHSS, idiopathic hypertrophic subaortic stenosis; ASH, asymmetrical septal hypertrophy; AV, atrioventricular.

Hypertrophic obstructive cardiomyopathy (HOCM), asymmetrical septal hypertrophy (ASH), and idiopathic hypertrophic subaortic stenosis (IHSS) are all synonymous terms applied to a form of an idiopathic hypertrophic cardiomyopathy. However, it presents a picture that is typical of the problems encountered in virtually all forms of obstructive cardiomyopathy. The salient anatomic feature of HOCM is hypertrophy of ventricular muscle at the base of the septum in the LVOT. Histologically, this is a disorganized mass of hypertrophied myocardial cells extending from the left ventricular septal wall, often involving the papillary muscles. Intramural (“small vessel”) coronary artery disease has been identified in autopsy specimens, especially in areas of myocardial fibrosis. This may represent a congenital component of the disease and probably plays some role in the etiology of myocardial ischemia in these patients.^[34]

Obstruction of the LVOT is caused by the hypertrophic muscle mass and systolic anterior motion (SAM) of the anterior leaflet of the mitral valve. SAM was thought to be caused by a Venturi effect of the rapidly flowing blood in the LVOT. Recently, echocardiographic data have revealed that excessive anterior mitral valve tissue in combination with a more anterior position of the mitral valve causes the anterior mitral valve leaflet to protrude into the LVOT.^[35]

A subaortic pressure gradient is present in symptomatic patients. The outflow tract obstruction can result in hypertrophy of the remainder of the ventricular muscle, secondary to increased pressures in the ventricular chamber. As the ventricle hypertrophies, ventricular compliance decreases and passive filling of the ventricle during diastole is impaired. For this reason, the ventricle becomes increasingly dependent on the presence of atrial contraction to maintain adequate ventricular end-diastolic volume. Occasionally, HOCM is associated with a right ventricular outflow tract obstruction as well.

The determinants of the functional severity of the ventricular obstruction in HOCM are (1) the systolic volume of the ventricle, (2) the force of ventricular contraction, and (3) the transmural pressure distending the outflow tract. Large systolic volumes in the ventricle distend the outflow tract and reduce the obstruction, whereas small systolic volumes narrow the outflow tract and increase the obstruction. When ventricular contractility is high, the outflow tract is narrowed, increasing the obstruction. When aortic pressure is high, there is an increased transmural pressure that distends the left ventricular outflow tract. During periods of hypotension, however, the outflow tract is narrowed. This results in markedly impaired cardiac output and sometimes mitral regurgitation, as the mitral valve becomes the relief point for ventricular pressure.

The current therapeutic options for patients with hypertrophied cardiomyopathy are based on pharmacologic therapy, surgical interventions, percutaneous transluminal septal myocardial ablation, and dual chamber pacing.^{[36] [37] [38] [39] [40]} Automatic implantable cardioverter-defibrillators are frequently implanted to treat arrhythmias and to prevent sudden cardiac death.^{[41] [42]} The pharmacologic therapy of HOCM has been based on β-blockers. However, it is still not clear if life expectancy is prolonged by this treatment. Verapamil has been used with increasing frequency in patients who do not tolerate β-blockers. Its beneficial effects are likely due to a depression of systolic function and an improvement in diastolic filling and relaxation. In patients whose symptoms are inadequately controlled with β-blockers or verapamil, disopyramide, a type Ia antiarrhythmic agent with negative inotropic and peripheral vasoconstrictive effects, has been used. Amiodarone is increasingly administered to HOCM patients for the control of supraventricular and ventricular arrhythmias.^[43]

Most patients with HOCM are treated with only medical therapy. Nevertheless, 5% to 30% of patients with HOCM are candidates for surgical therapy. The surgical intervention in HOCM is myotomy/myomectomy, mitral valve repair/replacement, or valvuloplasty, or a combination of these procedures.^[44] The potential complications of surgical correction of the LVOT obstruction include complete heart block and late formation of a ventricular septal defect due to septal infarction. Percutaneous transluminal alcohol septal ablation is performed in the catheterization laboratory but should be restricted to centers with specific experience. At this time it is not regarded as first-line therapy.^[45]

Controlled studies did not confirm earlier reports that atrioventricular sequential (DDD) pacing is beneficial for patients with HOCM. Thus, the role of biventricular pacing in subgroups of patients with HOCM has yet to be defined.^[46]

Anesthetic Considerations

HOCM had been suggested as a high-risk lesion associated with very high perioperative morbidity in noncardiac surgery.^[46a] Based on a retrospective review of perioperative care in 35 patients, it was concluded that the risk of general anesthesia and major noncardiac surgery is low in such patients. However, it was suggested that spinal anesthesia may be relatively contraindicated. Haering and colleagues studied 77 patients with asymmetrical septal hypertrophy who were retrospectively identified from a large database.^[46b] Forty percent of patients had one or more adverse perioperative cardiac events, including one patient who had a myocardial infarction and ventricular tachycardia that required emergent cardioversion, whereas the majority of the events were perioperative congestive heart failure. There were no perioperative deaths. Important independent risk factors for adverse outcome in all patients include major surgery and increasing duration of surgery. Unlike the original cohort of patients, type of anesthesia was not an independent risk factor.

Patients with HOCM may be extremely sensitive to small changes in ventricular volume, blood pressure, and heart rate and rhythm. Accordingly, monitoring should be established that allows continuous assessment of these parameters, particularly in patients in whom the obstruction is severe. In patients with HOCM coming to surgery for mitral valve repair/replacement and/or septal myomectomy, the electrocardiogram, an indwelling arterial catheter (and, in most institutions, a pulmonary artery catheter) are necessary monitors. TEE provides useful data on ventricular function and filling, the severity of LVOT obstruction, and the occurrence of SAM and mitral regurgitation. Assessment of the adequacy of repair requires an experienced echocardiographer.

In patients with HOCM coming for other procedures, the hemodynamic monitors should provide some indication of ventricular volume, force of ventricular contraction, and transmural pressure distending the outflow tract. An indwelling arterial catheter is almost always indicated for beat-to-beat observation of ventricular ejection during major regional or general anesthesia in patients with symptomatic HOCM. Intraoperative echocardiography is the most accurate monitor of ventricular loading conditions and performance in HOCM.

In the anesthetic management of patients with HOCM, special consideration should be given to those features of the surgical procedure and anesthetic drugs that can produce changes in intravascular volume, ventricular contractility, and transmural distending pressure of the outflow tract. Decreased preload, for example, can be produced by blood loss, sympathectomy secondary to spinal or epidural anesthesia, the use of nitroglycerin, or postural changes. Ventricular contractility can be increased by hemodynamic responses to tracheal intubation or surgical stimulation. Transmural distending pressure can be decreased by hypotension secondary to anesthetic drugs, hypovolemia, or positive-pressure ventilation. In addition, patients with HOCM do not tolerate increases in heart rate. Tachycardia decreases systolic ventricular volume and results in a narrowed outflow tract. As noted earlier, the atrial contraction is extremely important to the hypertrophied ventricle. Nodal rhythms should be aggressively treated, using atrial pacing if necessary.

Halothane has major hemodynamic advantages for the anesthetic management of patients with this condition. Halothane decreases heart rate and myocardial contractility, has the least effect of the inhalational anesthetics on SVR, and tends to minimize the severity of the obstruction when volume replacement is adequate. Isoflurane and enflurane cause more peripheral vasodilatation than halothane and are less desirable for this reason. Sevoflurane also decreases SVR to a lesser extent, and thus may be preferable. Agents that release histamine, such as morphine and many benzyl isoquinolinium neuromuscular blockers, are not recommended because of the venodilation they produce. Agents with sympathomimetic side effects (i.e., ketamine and desflurane) are not recommended. High-dose opioid anesthesia causes minimal cardiovascular side effects along with bradycardia and thus may be a useful anesthetic technique in these patients. Preoperative β-blocker and calcium channel blocker therapy should be continued. Intravenous propranolol, esmolol, or verapamil may be administered intraoperatively to improve hemodynamic performance. Table 2-6 summarizes the anesthetic and circulatory management of HOCM.

TABLE 2-6 -- Treatment Principles of Hypertrophic Obstructive Cardiomyopathy

Clinical Problem	Treatment	Relatively Contraindicated
↓ Preload	Volume	Vasodilators
	Phenylephrine	Spinal, epidural
↑ Heart Rate	β-Blockers	Ketamine
	Verapamil	β Agonists
↑ Contractility	Halothane	Positive inotropes
	Sevoflurane	Light anesthesia
	β-Blockers
	Disopyramide
↓ Afterload	Phenylephrine	Isoflurane
		Spinal, epidural

Anesthesia for Management of Labor and Delivery.

Anesthesia for management for labor and delivery in the parturient with HOCM is quite complex. β-Blocker therapy may have been discontinued during pregnancy because of the association with fetal bradycardia and intrauterine growth retardation. Spinal and epidural anesthesia are relatively contraindicated because of the associated vasodilatation. If hypotension occurs during anesthesia, the use of β-agonists such as ephedrine may result in worsening outflow tract obstruction, whereas α-agonists such as phenylephrine could potentially result in uterine vasoconstriction. Nevertheless, the successful management of cesarean section with both general and epidural anesthetics has been reported.^{[49] [50]} However, careful titration of anesthetic agents and adequate volume loading (guided by invasive monitoring) is essential to the safe conduct of anesthesia in this clinical setting.

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

Restrictive Cardiomyopathy

Restrictive cardiomyopathies (i.e., restrictive/obliterative cardiomyopathies) are usually the end stage of myocarditis or of an infiltrative process of the myocardium, such as amyloidosis or hemochromatosis ( Table 2-7 ). When a restrictive cardiomyopathy occurs, it mimics constrictive pericarditis coupled with myocardial dysfunction. Pulsus alternans occurs in both restrictive cardiomyopathies and constrictive pericarditis. Restrictive cardiomyopathies are characterized by impaired ventricular filling and poor ventricular contractility. Cardiac output is maintained in the early stages by elevated filling pressures and an increased heart rate. However, in contrast to constrictive pericarditis, an increase in myocardial contractility to maintain cardiac output is usually not possible. Endocardial fibroelastosis appears similar to restrictive cardiomyopathy in that there is impairment of diastolic ventricular filling but differs in that contractility is not usually impaired.^[49]

TABLE 2-7 -- Cardiomyopathies (Restrictive/Obliterative—Including Restrictive Endocarditis)

Disease Process	Mechanism	Associated Circulatory Problems	Miscellaneous
End stage of acute myocarditis	Fibrous replacement of myofibrils
Metabolic	Amyloid infiltration of myocardium	Valvular malfunction
		Coronary artery disease
Amyloidosis
Hemochromatosis	Iron deposition and secondary fibrous proliferation	Conduction abnormalities
Drugs—methysergide (Sansert)	Endocardial fibroelastosis	Valvular stenosis	Similar to changes in carcinoid syndrome
Restrictive endocarditis	Picture very similar to constrictive pericarditis
Carcinoid	Serotonin-producing carcinoid tumors—but serotonin is apparently not causative agent for fibrosis	Pulmonary stenosis
		Tricuspid insufficiency and/or stenosis
		Right-sided heart failure
Endomyocardial fibrosis	Fibrous obliteration of ventricular cavities	Mitral and tricuspid insufficiency
Loeffler's disease	Fibrosis of endocardium with decreased myocardial contraction	Subendocardial and papillary muscle degeneration and fibrosis
Becker's disease	Similar to Loeffler's	Similar to Loeffler's

Anesthetic Considerations

Anesthetic and monitoring considerations in restrictive cardiomyopathies are virtually identical to those of constrictive pericarditis and cardiac tamponade, with the additional feature of poor ventricular function. The combination of a restrictive and a dilated cardiomyopathy results in a more precarious situation than with either condition alone. The reader is referred to the section on constrictive pericarditis for a more detailed discussion of the physiology and management of restrictive ventricular filling and to the section on dilated cardiomyopathy for the management of impaired ventricular function. The anesthetic management must be tailored for whichever feature, restrictive physiology or heart failure, is predominant in a particular patient.

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

CARDIAC TUMORS

Primary tumors of the heart are unusual. However, the likelihood of encountering a cardiac tumor increases when metastatic tumors of the heart and pericardium are considered. For example, breast and lung cancers metastasize frequently to the heart.^[50] Two-dimensional echocardiography and angiography are the major modalities for the preoperative diagnosis of these lesions. Primary cardiac tumors may occur in any chamber or in the pericardium and may arise from any cardiac tissue. Of the benign cardiac tumors, myxoma is the most common, followed by lipoma, papillary fibroelastoma, rhabdomyoma, fibroma, and hemangioma ( Table 2-8 ).^[51]

TABLE 2-8 -- Primary Neoplasms of the Heart and Pericardium

Type	No. Cases	Percentage
Benign
Myxoma	130	29.3
Lipoma	45	10.1
Papillary fibroelastoma	42	9.5
Rhabdomyoma	36	8.1
Fibroma	17	3.8
Hemangioma	15	3.4
Teratoma	14	3.2
Mesothelioma of atrioventricular node	12	2.7
Granular cell tumor	3	0.7
Neurofibroma	3	0.7
Lymphangioma	2	0.5
Subtotal	319	72.0
Malignant
Angiosarcoma	39	8.8
Rhabdomyosarcoma	26	5.8
Mesothelioma	19	4.2
Fibrosarcoma	14	3.2
Malignant lymphoma	7	1.6
Extraskeletal osteosarcoma	5	1.1
Neurogenic sarcoma	4	0.9
Malignant teratoma	4	0.9
Thymoma	4	0.9
Leiomyosarcoma	1	0.2
Liposarcoma	1	0.2
Synovial sarcoma	1	0.2
Subtotal	125	28.0
Total	444	100.0

Adapted with permission from McAllister HA Jr, Fenoglio JJ Jr: Tumors of the cardiovascular system. In Atlas of Tumor Pathology (Fascicle 15). Washington, D.C., Armed Forces Institute of Pathology, 1978.

The generally favorable prognosis for patients with benign cardiac tumors is in sharp contrast to the prognosis for those with malignant cardiac tumors. The diagnosis of a malignant primary cardiac tumor is seldom made before extensive local involvement and metastasis have occurred, making curative surgical resection an unlikely event. An aggressive approach including surgery, radiotherapy, and chemotherapy has not significantly altered the poor outlook for these patients.^[52]

Benign Cardiac Tumors

Myxomas are most frequently benign tumors. They typically originate from the region adjacent to the fossa ovalis and project into the left atrium. They are usually pedunculated masses that resemble an organized clot on microscopy and may be gelatinous or firm. A left atrial myxoma may prolapse into the mitral valve during diastole. This prolapsing action results in a ball-valve obstruction to left ventricular inflow that mimics mitral stenosis, and may also cause valvular damage by a “wrecking ball” effect. More friable tumors result in systemic or pulmonary embolization, depending on their location and on the presence of any intracardiac shunts. Cerebral arterial aneurysms are associated with cerebral embolization of myxoma tissue. Pulmonary hypertension may be present due to mitral valve obstruction or regurgitation caused by a left atrial myxoma or pulmonary embolization in the case of a right atrial myxoma. Atrial fibrillation may be present secondary to atrial volume overload. Two-dimensional echocardiography can delineate the location and consistency of these tumors with good precision. Angiography is also valuable but may be complicated by catheter-induced embolization of tumor fragments. Surgical therapy requires careful manipulation of the heart before the institution of cardiopulmonary bypass to avoid embolization and also resection of the base of the tumor (with repair by patching) to prevent recurrence.^[53]

Other benign cardiac tumors occur less frequently. In general, intracavitary tumors result in valvular dysfunction or obstruction to flow and tumors localized in the myocardium cause conduction abnormalities and arrhythmias. Papilloma (papillary fibroelastoma) is usually a single villous connective tissue tumor that results in valvular incompetence or coronary ostial obstruction. Cardiac lipoma is an encapsulated collection of mature fat cells. Lipomatous hypertrophy of the interatrial septum is a related disorder that may result in right atrial obstruction. Rhabdomyoma is a tumor of cardiac muscle that occurs in childhood and is associated with tuberous sclerosis. Fibroma is another childhood cardiac tumor.^[54]

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

Malignant Cardiac Tumors

Ten to 25 percent of primary cardiac tumors are malignant, and almost all of these are sarcomas.^[55] The curative therapy of sarcomas is based on wide local excision that is not possible in the heart. In addition, the propensity toward early metastasis contributes to the dismal prognosis. Rhabdomyosarcoma may occur in neonates, but most cardiac sarcomas occur in adults. Sarcomas may originate from vascular tissue, cardiac or smooth muscle, and any other cardiac tissue. Palliative surgery may be indicated to relieve symptoms due to mass effects.^[56] These tumors respond poorly to radiotherapy and chemotherapy.^[57]

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

Metastatic Tumors Involving the Heart

Breast cancer, lung cancer, lymphomas, and leukemia may all result in cardiac metastases. About one fifth of patients who die of cancer have cardiac metastases. Thus, metastatic cardiac tumors are much more common than primary ones. Myocardial involvement results in congestive heart failure and may be classified as a restrictive cardiomyopathy. Pericardial involvement results in cardiac compression due to tumor mass or tamponade due to effusion. Melanoma is particularly prone to cardiac metastasis.^[58]

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

Cardiac Manifestations of Extracardiac Tumors

Carcinoid is a tumor of neural crest origin that secretes serotonin, bradykinin, and other vasoactive substances. Hepatic carcinoid metastases result in right-sided valvular lesions, presumably from a secretory product that is metabolized in the pulmonary circulation. Recently, serotonin itself has been implicated in the pathogenesis of tricuspid valve dysfunction.^{[61] [62] [63]} The end results are thickened valve leaflets that may be stenotic or incompetent, although regurgitation is more common. Even though the tricuspid valve is most commonly involved, this process may involve both right- and left-sided valves.

Pheochromocytoma is a catecholamine-secreting tumor also of neural crest origin. Chronic catecholamine excess has toxic effects on the myocardium that may result in a dilated cardiomyopathy.^[62]

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

Anesthetic Considerations

The presence of a cardiac tumor requires a careful preoperative echocardiographic assessment of cardiac morphology and function. A right-sided tumor (especially myxoma) is a relative contraindication to pulmonary artery catheter insertion because of the risk of embolization, although it may be possible to advance the catheter through the right ventricle after the tumor is resected. The removal of intracardiac tumors is a category II indication for intraoperative TEE monitoring and is particularly useful in the evaluation of the surgical intervention ( Fig. 2-3 ). Left atrial myxomas are well visualized by this technique. However, caution should be exercised in the manipulation of the TEE probe to prevent embolization of friable tumors attached to the posterior wall of the left atrium, because of the proximity of the probe. The management of a left atrial myxoma is similar to that of mitral stenosis. A slow heart rate and high preload should maximize ventricular filling in the presence of an obstructing tumor.



FIGURE 2-3 A, Transesophageal image of a mass on the right cusp of the aortic valve. B, Photograph of the resected aortic valve (from the same patient) with the tumor attached to the right cusp.

In the absence of a right-sided intracavitary tumor, pulmonary artery catheterization is useful for assessing cardiac function impaired by restrictive cardiomyopathy, pericardial tumor, pericardial effusion, or an obstructive lesion. Avoidance of myocardial depressants, such as the potent volatile agents, and the maintenance of an adequate heart rate are optimal in this scenario. Lower induction doses of ketamine (0.25 to 1.0 mg/kg) or the use of etomidate should minimize hypotension on induction with severely compromised ventricular function.

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

ISCHEMIC HEART DISEASE

The most important aspects of coronary artery disease remain the same no matter what the etiology of the obstruction of the coronary arteries ( Table 2-9 ). Like coronary artery disease produced by arteriosclerosis, the coronary artery disease produced by an uncommon disease retains the same key clinical features. Physiologic considerations remain essentially the same, as do treatment and anesthetic management.

TABLE 2-9 -- Uncommon Causes of Coronary Artery Disease

Coronary Artery Disease Associated with Cardiomyopathy (Poor Left Ventricular Function)

Pathologic basis—infiltration of coronary arteries with luminal narrowing

	1.	Amyloidosis—valvular stenosis, restrictive cardiomyopathy
	2.	Fabry's disease—hypertension
	3.	Hurler's syndrome—often associated with valvular malfunction
	4.	Hunter's syndrome—often associated with valvular malfunction
	5.	Primary xanthomatosis—aortic stenosis
	6.	Leukemia—anemia
	7.	Pseudoxanthoma elasticum—valve abnormalities

Inflammation of coronary arteries

	1.	Rheumatic fever—in acute phase
	2.	Rheumatoid arthritis—aortic and mitral regurgitation, constrictive pericarditis
	3.	Periarteritis nodosa—hypertension
	4.	Systemic lupus erythematosus—hypertension, renal failure, mitral valve malfunction

Embolic or thromboembolic occlusion of coronary arteries

	1.	Schistosomiasis
	2.	Sickle cell anemia—cor pulmonale depending on length and extent of involvement

Fibrous and hyaline degeneration of coronary arteries

	1.	Post transplantation
	2.	Radiation
	3.	Duchenne's muscular dystrophy
	4.	Friedreich's ataxia—? associated with hypertrophic obstructive cardiomyopathy
	5.	Roussy-Lévy—hereditary polyneuropathy

Anatomic abnormalities of coronary arteries

	1.	Bland-White-Garland syndrome (left coronary artery arising from pulmonary artery)—endocardial fibroelastosis, mitral regurgitation
	2.	Ostial stenosis secondary to ankylosing spondylitis—aortic regurgitation

II.

Coronary Artery Disease Usually Associated with Normal Ventricular Function

Anatomic abnormalities of coronary arteries

	1.	Right coronary arising from pulmonary artery
	2.	Coronary arteriovenous fistula
	3.	Coronary sinus aneurysm
	4.	Dissecting aneurysm
	5.	Ostial stenosis—bacterial overgrowth syphilitic aortic
	6.	Coronary artery trauma—penetrating or nonpenetrating
	7.	Spontaneous coronary artery rupture
	8.	Kawasaki's disease—coronary artery aneurysm

Embolic or thrombotic occlusion

	1.	Coronary emboli
	2.	Malaria and/or malarial infested red blood cells
	3.	Thrombotic thrombocytopenic purpura
	4.	Polycythemia vera

Infections

	1.	Miliary tuberculosis—intimal involvement of coronary arteries
	2.	Arteritis secondary to salmonella or endemic typhus (associated with active myocarditis)

Infiltration of coronary arteries

	1.	Gout – conduction abnormalities, possible valve problems
	2.	Homocystinuria

Coronary artery spasm

Cocaine

Miscellaneous

	1.	Thromboangiitis obliterans (Buerger's disease)
	2.	Takayasu's arteritis

In the preoperative assessment, the symptoms produced by the coronary artery disease should be determined. The obvious symptoms to look for in the history are angina, the patient's exercise limitations, and symptoms of myocardial failure, such as orthopnea or paroxysmal nocturnal dyspnea. The physical examination retains its importance, especially when quantitative data regarding cardiac involvement are not available. Physical findings such as S3 and S4 heart sounds are important, as are auscultatory signs of uncommon conditions such as cardiac bruits, which might occur in a coronary arteriovenous fistula. If catheterization data are available, the specifics of coronary artery anatomy and ventricular function, such as end-diastolic pressure, ejection fraction, and the presence of wall motion abnormalities, are all useful. Information on ventricular perfusion and function can also be obtained by noninvasive means such as echocardiography and nuclear imaging.^{[65] [66]}

After ascertaining the extent of coronary insufficiency, the special aspects of the disease entity producing the coronary insufficiency should be considered. As an example, in ankylosing spondylitis, coronary insufficiency is produced by ostial stenosis, yet valvular problems often coexist and even overshadow the coronary artery disease.^[65] In rheumatoid arthritis, however, airway problems may be the most significant part of the anesthetic challenge. Hypertension, which frequently coexists with arteriosclerotic coronary artery disease, is also a feature of the coronary artery disease produced by Fabry's disease. Other features to consider are metabolic disturbances that coexist with the coronary artery disease, such as when systemic lupus erythematosus produces both coronary artery disease and renal failure.^[66]

Physiology of Coronary Artery Disease and its Modification by Unusual Diseases

The key to the physiology of coronary artery disease is the balance of myocardial oxygen supply and demand ( Fig. 2-4 ). Myocardial oxygen supply depends on many factors, including the heart rate, patency of the coronary arteries, hemoglobin concentration, PaO₂, and the coronary perfusion pressure. The same factors determine supply in uncommon diseases, but the specific manner in which an uncommon disease modifies these factors should be sought. A thorough knowledge of the anatomy of the coronary circulation and how the disease process can affect arterial patency is a useful starting point. This information is usually gained from coronary angiography. In the assessment of the adequacy of coronary perfusion, the viscosity of the blood should be considered, because flow is a function both of the dimensions of the conduit and the nature of the fluid in the system. In disease processes such as thrombotic thrombocytopenic purpura, sickle cell disease, or polycythemia vera, the altered blood viscosity can assume critical importance.^{[69] [70] [71] [72]}



FIGURE 2-4 Myocardial oxygen supply and demand balance.

Oxygen-carrying capacity must also be considered in certain uncommon disease states. Hemoglobin concentration is usually not a limiting factor in the supply of oxygen to the myocardium. However, in diseases such as leukemia, anemia may be a prominent feature, and the myocardial oxygen supply may be reduced accordingly. Another example is myocardial ischemia in carbon monoxide poisoning, where the hemoglobin, albeit quantitatively sufficient, cannot carry oxygen. Similarly, the PaO₂ is usually not a limiting factor. But in conditions where coronary artery disease exists concomitantly with cor pulmonale, as in schistosomiasis or sickle-cell disease, the inability to maintain adequate oxygenation may limit the myocardial oxygen supply. In fact, in sickle cell disease, it may be the key feature, because the failure to maintain an adequate PaO₂, secondary to repeated pulmonary infarctions, further increases the tendency of cells containing hemoglobin-S to sickle, compromising myocardial oxygen delivery through “sludging” in the coronary microcirculation.^[71]

The major factors determining myocardial oxygen demand include heart rate, ventricular wall tension, and myocardial contractility. Tachycardia and hypertension after tracheal intubation, skin incision, or other noxious stimuli are common causes of increased myocardial oxygen demand during surgery. Additionally, complicating factors of an unusual disease may also produce increases in demand. Increases in rate may occur as a result of tachyarrhythmias secondary to sinoatrial (SA) or AV node involvement in amyloidosis or in Friedreich's ataxia. Increases in wall tension, for example, may occur in severe hypertension associated with systemic lupus erythematosus, periarteritis nodosa, or Fabry's disease. Outflow tract obstruction with increased ventricular work can occur in primary xanthomatosis or in tertiary syphilis; and an increase in the diastolic ventricular radius with increased wall tension can occur in situations such as aortic regurgitation associated with ankylosing spondylitis.

Modern cardiac anesthesia practice should tailor the anesthetic management to the problems posed by the peculiarities of the coronary anatomy. For example, knowledge of the presence of a lesion in the left main coronary artery dictates great care during anesthesia to avoid even modest hypotension or tachycardia. Lesions of the right coronary artery are known to be associated with an increased incidence of atrial arrhythmias and heart block, and steps must be taken either to treat these or to compensate for their cardiovascular effects.

In diseases such as primary xanthomatosis or Hurler's syndrome, the infiltrative process that produces coronary artery disease usually involves the coronary arteries diffusely, but some diseases may have features that can mimic either isolated left main coronary artery disease or right coronary artery disease. The Bland-White-Garland syndrome, which is anomalous origin of the left coronary artery from the pulmonary artery, and coronary ostial stenosis produced by aortic valve prosthesis may both behave as left main coronary artery disease. A similar syndrome could be produced by bacterial overgrowth of the coronary ostia, ankylosing spondylitis, a dissecting aneurysm of the aorta, or Takayasu's arteritis. Right coronary artery disease could be mimicked by the syndrome of the anomalous origin of the right coronary artery from the pulmonary artery or by infiltration of the SA or AV nodes in amyloidosis or Friedreich's ataxia. In small artery arteritis, which occurs in periarteritis nodosa or systemic lupus erythematosus, the small arteries supplying the SA or AV nodes may be involved in the pathologic process, producing ischemia of the conduction system.

In Table 2-9 , the uncommon diseases that produce coronary artery disease have been divided into those that produce coronary artery disease associated with good left ventricular function and those associated with poor left ventricular function. In any of these diseases, ventricular function can regress from good to poor. In some conditions, the coronary artery disease progression and ventricular function deterioration occur at the same rate and left ventricular function is eventually severely depressed. In other situations, coronary insufficiency is primary and left ventricular dysfunction eventually occurs after repeated episodes of ischemia and/or thrombosis. Ventricular function must be evaluated by clinical signs and symptoms, echocardiography, nuclear imaging, or cardiac catheterization. The converse is severe arterial disease coupled with relatively good left ventricular function. This is the picture of a cardiomyopathy associated with almost incidental coronary artery disease, as occurs in Hurler's syndrome, amyloidosis, or systemic lupus erythematosus. Most anatomic lesions, such as Kawasaki disease, coronary AV fistula, or coronary insufficiency produced by trauma are usually associated with good left ventricular function. There is a clinical gray zone in which coronary artery disease and poor left ventricular function coexist without either process clearly predominating, such as with tuberculosis and syphilis. These can only be characterized by investigating the extent of involvement of the coronary arteries and the myocardium in the disease process. The following is a more detailed discussion on a few selected disease states that affect the coronary arteries.

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

Some Uncommon Causes of Ischemic Heart Disease

Coronary Artery Spasm

The luminal narrowing of the coronary arteries secondary to spasm has been associated with angina and myocardial infarction.^[72] The mechanism of coronary artery spasm remains unclear. The smooth muscle cells of the coronary artery walls may contract in response to various stimuli. There may be abnormal responses to various vasoactive substances,^{[75] [76]} and, in addition, there may be increased α-adrenergic tone.^[75] Another theory is that vessels with eccentric atherosclerotic plaques have a segment of disease-free wall that may be a site for vasospasm, which can convert an insignificant obstruction into a critical lesion. Coronary artery vasospasm may respond to nitroglycerin and calcium channel blockers.

Cocaine Abuse

Cocaine can affect the heart in several ways, and the use of cocaine can result in myocardial ischemia, myocardial infarction, and sudden death.^{[78] [79]} Cocaine exerts its effects on the heart mainly by two mechanisms: (1) its ability to block sodium channels resulting in a local anesthetic or membrane-stabilizing property and (2) its ability to block the reuptake of norepinephrine resulting in increased sympathetic activity. It is not surprising, therefore, that cocaine, when administered acutely, has been shown to have a biphasic effect on left ventricular function with transient depression followed by a sustained increase in contractility.^[78] Cocaine also induces coronary vasospasm and reduced coronary blood flow, while at the same time increasing heart rate and blood pressure. These effects will decrease myocardial oxygen supply and increase myocardial oxygen demand. In addition, cocaine and its metabolites can induce platelets to aggregate and release platelet-derived growth factor that can promote fibrointimal proliferation and accelerated atherosclerosis.^[79] Chronic users of cocaine also have an exaggerated response to sympathetic stimuli, which may contribute to the left ventricular hypertrophy frequently observed among chronic users.

Coronary Artery Dissection

When there is separation of the intimal layer from the medial layer of the coronary artery, there may be obstruction of the true coronary artery lumen with subsequent distal myocardial ischemia. Coronary artery dissection may be primary or secondary. Primary coronary artery dissection may occur during coronary artery catheterization or angioplasty and in trauma to the heart. Primary coronary artery dissection may also occur spontaneously. Spontaneous dissection is usually associated with coronary arterial wall eosinophilia and is seen in the postpartum period. Secondary coronary artery dissection is more common and is usually caused by a dissection in the ascending aorta.

Inflammatory Causes

Infectious Causes.

Infectious coronary artery arteritis may be secondary to hematogenous spread or secondary to direct extension from infectious processes of adjacent tissue. The infectious process results in thrombosis of the involved artery with myocardial ischemia. Syphilis is one of the most common infectious agents to affect the coronary arteries. Up to 25% of patients with tertiary syphilis have ostial stenosis of their coronary arteries.^{[82] [83]}

Noninfectious Causes

Polyarteritis Nodosa.

This is a systemic necrotizing vasculitis involving medium and small vessels. Epicardial coronary arteries are involved in the majority of cases of polyarteritis nodosa. After the initial inflammatory response, the coronary artery may dilate to form small berry-like aneurysms that may rupture, producing fatal pericardial tamponade.

Systemic Lupus Erythematosus.

The pericardium and myocardium are usually affected in systemic lupus erythematosus (SLE). Patients with SLE, however, may suffer acute myocardial infarction in the absence of atherosclerotic coronary artery disease.^{[84] [85]} The hypercoagulable state of SLE, together with a predisposition to premature coronary atherosclerosis, has been implicated. In addition, glucocorticoids used for the treatment of SLE may also predispose these patients to accelerated atherosclerosis.

Kawasaki's Disease (Mucocutaneous Lymph Node Syndrome).

This is a disease of childhood. A vasculitis of the coronary vasa vasorum leads to weakened walls of the vessels with subsequent coronary artery aneurysm formation.^[84] Thrombosis and myocardial ischemia can also occur. These patients are prone to sudden death from ventricular arrhythmias and occasionally from rupture of a coronary artery aneurysm. Thrombus in the aneurysm may also embolize, causing myocardial ischemia.^[85]

Takayasu's Disease.

This disease leads to fibrosis and luminal narrowing of the aorta and its branches. The coronary ostia may be involved in this process.^[86]

Metabolic Disorders

Homocystinuria.

An increased incidence of atherosclerotic disease in patients with high levels of homocysteine is reported.^[87] This process may involve intimal proliferation of small coronary vessels and an increased risk of myocardial infarction. Nevertheless, meta-analysis and prospective studies have not consistently confirmed these findings.^{[90] [91]}

Congenital Abnormalities of the Coronary Arterial Circulation

Left Coronary Artery Arising from the Pulmonary Artery.

This is also known as Bland-White-Garland syndrome. The right coronary arises from the aorta, but the left coronary arises from the pulmonary artery. Flow in the left coronary arterial system is retrograde, with severe hypoperfusion of the left ventricle with myocardial ischemia and infarction. As such, most patients with this disease present in infancy with evidence of heart failure. Untreated patients usually die during infancy. Patients who survive childhood may present with mitral regurgitation from annular dilatation. The goals of medical therapy are to treat congestive heart failure and arrhythmias. The defect can be corrected surgically by primary anastomosis of the left coronary artery to the aorta.^{[92] [93]} In older children, a vein graft of the left internal mammary artery may be used to establish anterograde flow in the left coronary arterial system. Improvement in left ventricular function can be expected of surgical survivors if this operation is performed early.^{[94] [95]}

Coronary Arteriovenous Fistula.

There is an anatomic communication between a coronary artery and a right-sided structure such as the right atrium, right ventricle, or the coronary sinus. The right coronary artery is more frequently affected and is usually connected to the coronary sinus. Most patients are asymptomatic. These patients are at risk for endocarditis, myocardial ischemia, and rupture of the fistulous connection.^[94] These fistulas should be corrected surgically.^[95]

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

Anesthetic Considerations

The functional impairment of the myocardium and coronary circulation dictates the extent and type of monitoring to be employed. The selection of ECG leads to monitor is dictated by knowledge of the coronary anatomy. Those diseases in which there is left coronary artery disease are best monitored using precordial leads, such as the V₅ lead. In those diseases with right coronary artery disease, ECG leads used to assess the inferior surface of the heart (leads II, III, or aVF), or the posterior surface (esophageal lead), are preferable.^{[98] [99] [100]}

Knowledge of ventricular filling pressures is especially important in diseases associated with poor ventricular function. The use of a pulmonary artery catheter is preferable to central venous pressure monitoring in the assessment of left ventricular function. The etiology of large V waves on the pulmonary capillary wedge pressure waveform that sometimes occur during myocardial ischemia is probably a decrease in diastolic ventricular compliance. However, large V waves did not correlate with other determinants of myocardial ischemia in a study of vascular surgical patients with coronary artery disease.^[99]

Two-dimensional TEE is an important monitor of both ventricular function and myocardial ischemia. It can demonstrate regional changes in wall motion that are sensitive signs of myocardial ischemia.^{[102] [103] [104]} Urine output is another important parameter and is especially significant in diseases associated with nephropathy, such as long-standing sickle cell disease or systemic lupus.

When severe cardiomyopathy associated with coronary artery disease exists, monitoring cardiac output and SVR is useful in evaluating both the effects of anesthetic drugs and therapeutic interventions. It is quite controversial whether pulmonary artery catheterization is indicated in patients requiring major procedures. In the absence of convincing evidence of outcome benefits associated with pulmonary artery catheterization, decisions regarding this type of monitoring should be made on a case-by-case basis. An indwelling arterial catheter for monitoring arterial blood gases is important, especially when pulmonary disease or cor pulmonale complicates the picture, as in schistosomiasis or sickle cell disease.

One caveat should be noted in the use of intra-arterial monitoring. When peripheral arterial monitoring is used in cases of generalized arteritis, the adequacy of collateral blood flow should be carefully evaluated before cannulation of the peripheral artery. In occlusive diseases, such as Raynaud's disease, Takayasu's arteritis, or Buerger's disease, or in cases of sludging in the microcirculation, as in sickle cell disease, the area distal to the cannulated artery should be checked frequently for signs of arterial insufficiency. Axillary artery catheterization may be preferable.

The anesthetic employed in these conditions should be tailored to the degree of myocardial dysfunction.^[103] In cases of pure coronary insufficiency with good left ventricular function, anesthetic management is aimed at decreasing oxygen demand by decreasing myocardial contractility, while preserving oxygen supply by maintaining blood pressure. Techniques commonly employed include the combination of a volatile anesthetic agent with nitrous oxide or use of a nitrous-narcotic technique that employs the intermittent use of vasodilators such as nitroprusside or nitroglycerin for control of hypertension.

When coronary vasospasm is considered, it is important to maintain a relatively high coronary perfusion pressure. Pharmacologic agents such as nitroglycerin and calcium channel blockers may also be used. Patients who are chronic users of cocaine should be considered at high risk for ischemic heart disease and arrhythmias. These patients may respond unpredictably to anesthetic agents and other drugs used in the perioperative period. Ephedrine and other indirect sympathomimetic drugs should be avoided in cocaine users.

In patients with poor ventricular function, the anesthetic technique should maintain hemodynamic stability by avoiding drugs that produce significant degrees of myocardial depression.^[104] High-dose opioid techniques or opioid-benzodiazepine combinations have been found to be effective.^[105] In periarteritis nodosa or Fabry's disease, hypertension is often associated with poor left ventricular function. In such situations, a vasodilator such as sodium nitroprusside or nitroglycerin can be used to control hypertension rather than a volatile anesthetic. Milrinone and nesiritide are also options. The principles for the management of intraoperative arrhythmias remain the same as for the treatment of arrhythmias in the setting of atherosclerotic coronary artery disease. Regional anesthesia requires monitoring that will allow the appropriate management of associated sympathetic blockade.

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

PULMONARY HYPERTENSION AND COR PULMONALE

Pulmonary Hypertension

Pulmonary hypertension is defined as an elevation of the mean pulmonary artery pressure above the accepted limit of normal, regardless of the etiology (mean pulmonary artery pressure > 25 mm Hg at rest or > 30 mm Hg during exercise).^{[108] [109]}

The normal pulmonary vasculature changes from a high resistance circuit in utero to a lower resistance circuit in the newborn, secondary to several concomitant changes: (1) the relief of hypoxic vasoconstriction that occurs with the first spontaneous breath; (2) the stenting effect of air-filled lungs on the pulmonary vessels, which increases their caliber and decreases their resistance; and (3) the functional closure of the ductus arteriosus, secondary to an increase in the PaO₂. The muscular medial layer of the fetal pulmonary arterioles normally involutes in postnatal life. Assuming there is no severe active vasoconstriction, pulmonary artery pressure remains low, owing to the numerous parallel vascular channels that accept increased blood flow as pulmonary blood volume is increased. For this reason, pressure is not normally increased in the pulmonary circuit, because increased pulmonary blood flow distends the pulmonary vessels, lowering their resistance.

General pathologic conditions that will convert this normally low resistance circuit into a high resistance circuit are summarized by the WHO Diagnostic Classification of Pulmonary Hypertension ( Table 2-10 ). The WHO lists five separate categories of pulmonary hypertension: (1) pulmonary arterial hypertension; (2) pulmonary venous hypertension; (3) pulmonary hypertension with disorders of the respiratory system and/or hypoxemia; (4) pulmonary hypertension caused by chronic thrombotic and/or embolic disease; and (5) pulmonary hypertension caused by disorders affecting the pulmonary vasculature directly.

TABLE 2-10 -- Diagnostic Classification of Pulmonary Hypertension

Rights were not granted to include this content in electronic media. Please refer to the printed book.

From Rubin LJ: Pulmonary hypertension. In Fuster V, Alexander RW, O’Rourke RA (eds): Hurts's The Heart. 11th ed. New York, McGraw-Hill, 2004, p 1579. Reproduced with permission of the McGraw-Hill Companies.

Increases in capillary or pulmonary venous pressure may be caused by conditions such as left ventricular failure, mitral regurgitation, or mitral stenosis. In addition to the passive increase in pulmonary blood volume, active vasoconstriction also occurs in the pulmonary vascular bed. Hypoxic vasoconstriction induced by ventilation-perfusion mismatching or reflex constriction occurring with the passive stretching of the muscular media of the pulmonary arterioles may be the basis of this phenomenon.^[108]

A decrease in pulmonary arterial cross-sectional area results in increased pulmonary vascular resistance, as dictated by Poiseuille's law, which states that resistance to flow is inversely proportional to the fourth power of the radius of the vessels. Very small decrements in a pulmonary cross-sectional area can result in striking increases in resistance. There are a number of causes of decreased pulmonary arterial cross-sectional area. Filarial worms, the eggs of Schistosoma mansoni, or multiple small thrombotic emboli are typical of embolic causes of pulmonary hypertension. Primary deposition of fibrin in the pulmonary arterioles and capillaries due to an altered hemostasis with prothrombotic mechanisms, especially increased platelet activation, is another cause of decreased cross-sectional area, and this, in fact, may be the mechanism of primary, or idiopathic, pulmonary hypertension.^{[111] [112]} This also may be the cause of the pulmonary arterial hypertension that is rarely associated with the use of oral contraceptives, which are known to increase thrombogenesis.

Pulmonary arterial medial hypertrophy can occur if there is increased flow or pressure in the pulmonary circulation early in life. In this situation, the muscular media of the pulmonary arterioles undergo hypertrophy rather than the normal postnatal involution.^[111] As the muscle hypertrophies there is increased reflex contraction in response to the elevations in pulmonary arterial pressure. This raises the pulmonary arterial pressure even higher by further reducing cross-sectional area. If this pulmonary arterial pressure elevation is of long standing, it results in intimal damage to the pulmonary arterioles followed by fibrosis, thrombosis, and sclerosis, with an irreversible decrease in cross-sectional area of the arterial bed, as often occurs in long-standing mitral valve disease or emphysema. Pulmonary hypertension can also be caused by primary vasoconstrictors, such as the seeds of the Crotalaria plant, or by hypoxia associated with high-altitude or pulmonary parenchymal disease.^[112]

Pulmonary hypertension resulting from increases in pulmonary arterial flow is usually associated with various congenital cardiac lesions, such as atrial septal defect, ventricular septal defect, patent ductus arteriosus, or, in adult life, ventricular septal defect occurring after a septal myocardial infarction. Hypoxemia will aggravate this situation. Evidence for this arises from the observation that there is an increased incidence of pulmonary hypertension in infants with congenital left-to-right shunting who are born at high altitudes, compared with similar infants born at sea level. Long-standing increases in flow with intimal damage may result in fibrosis and sclerosis, as noted earlier. An increase in pulmonary arterial pressure in these cases ultimately may result in Eisenmenger's syndrome, in which irreversibly increased pulmonary arterial pressure results in a conversion of left-to-right shunting to right-to-left shunting with the development of tardive cyanosis.

Like systemic arterial hypertension, pulmonary hypertension is characterized by a prolonged asymptomatic period. As pulmonary vascular changes occur, an irreversible decrease in pulmonary cross-sectional area develops and stroke volume becomes fixed as a result of the fixed resistance to flow. As such, cardiac output becomes heart rate dependent. This results in the symptoms of dyspnea, fatigue, syncope, and chest pain. The diagnostic dilemma presented by pulmonary hypertension is in differentiation of primary pulmonary hypertension from secondary pulmonary hypertension. Usually, in secondary pulmonary hypertension, the symptoms of the primary condition are the more prominent and the pulmonary hypertension is of secondary significance. When pulmonary hypertension exists alone, the key feature of its pathophysiology is a fixed cardiac output. Right ventricular hypertrophy commonly occurs in response to pulmonary hypertension, which may progress to right ventricular dilatation and failure.^[113]

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

Cor Pulmonale

Cor pulmonale is usually defined as an alteration in the structure and function of the right ventricle, such as right ventricular hypertrophy, dilation, and failure secondary to pulmonary arterial hypertension that is due to a decrease in the cross-sectional area of the pulmonary bed. This excludes, therefore, right ventricular failure, which occurs after increases in pulmonary arterial pressure secondary to increases in pulmonary blood flow or in pulmonary capillary or venous pressure. Both increases in pulmonary blood flow and passive increases in pulmonary venous and capillary pressure can produce right ventricular failure, but they do not, strictly speaking, produce cor pulmonale. The physiologic considerations in cor pulmonale and in right ventricular failure from other causes are similar. Given this restriction, though, there are still numerous causes of cor pulmonale, including pulmonary parenchymal disease, chronic hypoxia, and primary pulmonary arterial disease.^[114]

Cor pulmonale is divided into two types: acute and chronic. Acute cor pulmonale is usually secondary to a massive pulmonary embolus, resulting in a 60% to 70% decrease in the pulmonary cross-sectional area associated with cyanosis and acute respiratory distress. With acute cor pulmonale, there is a rapid increase in right ventricular systolic pressure to 60 to 70 mm Hg, which slowly returns toward normal secondary to displacement of the embolus peripherally, lysis of the embolus, and increases in collateral blood flow. These changes often occur within 2 hours of the onset of symptoms. Massive emboli may be associated with acute right ventricular dilatation and failure, elevated central venous pressure, and cardiogenic shock. Another feature of massive pulmonary embolization is the intense pulmonary vasoconstrictive response.^{[117] [118]}

Chronic cor pulmonale presents with a different picture. It is associated with right ventricular hypertrophy and/or dilatation and a change in the normal crescentic shape of the right ventricle to a more ellipsoidal shape. This configuration is consistent with a change from volume work that the right ventricle normally performs, to the pressure work required by a high afterload. Left ventricular dysfunction may occur in association with right ventricular hypertrophy. This dysfunction cannot be related to any obvious changes in the loading conditions of the left ventricle but is probably due to displacement of the interventricular septum. Chronic cor pulmonale is usually superimposed on long-standing pulmonary arterial hypertension that is associated with chronic respiratory disease.^[117]

Chronic bronchitis is probably the most common cause of cor pulmonale in adults, and its pathophysiology will be examined as a guide to understanding and managing cor pulmonale from all causes. Initially, the pulmonary vascular resistance in chronic bronchitis is normal or slightly increased because cardiac output increases. Later, there is a further increase in pulmonary vascular resistance or an inappropriately elevated pulmonary vascular resistance for the amount of pulmonary blood flow. Recall that in the normal situation there is a slight decrease in the pulmonary resistance when pulmonary blood flow is increased that is probably secondary to an increase in pulmonary vascular diameter and in flow through collateral channels. In chronic bronchitis, the absolute resistance of the pulmonary circulation may not change, owing to the inability of the resistance vessels to dilate. A progressive loss of pulmonary parenchyma occurs and, because of dilatation of the terminal bronchioles, there is an increase in pulmonary dead space that causes progressively more severe mismatching of pulmonary ventilation and perfusion. In response to the ventilation-perfusion mismatch, the pulmonary circulation attempts to compensate by decreasing blood flow to the areas of the lung that have hypoxic alveoli. This occurs at the expense of a decrease in pulmonary arteriole cross-sectional area and an elevation in pulmonary arterial pressure.^[118]

Long-standing chronic bronchitis results in elevations in pulmonary arterial pressure, with resulting alterations in the structure and function of the right ventricle, such as right ventricular hypertrophy. In any form of respiratory embarrassment, whether it is infection or simply progression of the primary disease, further increases in pulmonary vascular resistance increase pulmonary arterial pressure, and right ventricular failure supervenes. With the onset of respiratory problems in the patient with chronic bronchitis, a number of changes occur that can make pulmonary hypertension more severe and can precipitate right ventricular failure. A respiratory infection produces further abnormalities of the blood gas values, with declines in PaO₂ and elevations in PaCO₂. Generally the pulmonary artery pressure is directly proportional to the PaCO₂, though the pulmonary circulation also vasoconstricts in response to hypoxemia. With a fall in PaO₂ there is usually an increase in cardiac output in an effort to maintain oxygen delivery to tissues. This increased blood flow through the lungs may result in further elevations in the pulmonary artery pressure owing to the fixed decreased cross-sectional area of the pulmonary vascular bed. In addition, patients with chronic bronchitis and long-standing hypoxemia often have compensatory polycythemia. The polycythemic blood of the chronic bronchitis produces an increased resistance to flow through the pulmonary circuit because of its increased viscosity, and attempts to increase cardiac output during respiratory compromise simply make the situation worse.

The patient with chronic bronchitis normally has an increase in airway resistance made worse during acute respiratory infection as a result of secretions and edema that further decrease the caliber of the small airways. These patients also have a loss of structural support from degenerative changes in the airways and from a loss of the stenting effect of the pulmonary parenchyma. For these reasons, the patient's small airways tend to collapse during exhalation and there is a rise in airway pressure from this “dynamic compression” phenomenon. In chronic bronchitis and emphysema the decrease in cross-sectional area of the pulmonary vessels results not from fibrotic obliteration of pulmonary capillaries or arterioles but rather from hypertrophy of the muscular media of the pulmonary arterioles. The vessels become compressible but not distensible, so that with exhalation and an increase in intrathoracic pressure, airway compression results in a further increase in pulmonary vascular resistance and an increase in pulmonary arterial pressure. The hypertrophied muscular media prevents the resulting increase in pulmonary arterial pressure from distending the pulmonary vessels and maintaining a normal pulmonary artery pressure. With the onset of respiratory embarrassment in the patient with chronic bronchitis, there are increases in pulmonary artery pressure, afterload, and the work requirement of the right ventricle that may result in right ventricular failure.

A similar pattern may be observed in other forms of pulmonary disease, since the compensatory mechanisms are much the same as in chronic bronchitis. Chronic bronchitis, however, is somewhat more amenable to therapy, because the acute pulmonary changes are often reversible. Relief of hypoxemia, for example, may be expected to afford some amelioration of the pulmonary hypertension. In pulmonary hypertension and cor pulmonale secondary to pulmonary fibrosis, relief of hypoxia probably has little to offer the pulmonary circulation, because the increase in pulmonary vascular resistance is due not to vasoconstriction of muscular pulmonary arterioles but rather to a fibrous obliteration of the pulmonary vascular bed.

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

Anesthetic Considerations

Monitoring for patients with pulmonary hypertension and cor pulmonale should provide a continuous assessment of pulmonary arterial pressure, right ventricular filling pressure, right ventricular myocardial oxygen supply/demand balance, and some measure of pulmonary function. The electrocardiogram allows for the monitoring of arrhythmias. In the setting of right ventricular hypertrophy where there is an increased possibility of coronary insufficiency, ECG monitoring allows observation of the development of ischemia or acute strain of the right ventricle, seen in the inferior, right precordial, or esophageal ECG leads.

Pulmonary artery pressure monitoring provides an indication of the workload imposed on the right ventricle in cor pulmonale. The pulmonary artery catheter affords the potential for monitoring the pulmonary artery pressure and also for monitoring the central venous pressure as an indication of the right ventricular filling pressure. Most anesthesiologists would choose to use pulmonary arterial monitoring in major surgical procedures associated with significant fluid shifts.

The pulmonary artery catheter can also aid in the distinction between left ventricular failure and respiratory failure. In left ventricular failure an elevated pulmonary artery pressure occurs with an elevated pulmonary capillary wedge pressure, whereas in respiratory failure there is often an elevation of pulmonary artery pressure with a normal pulmonary capillary wedge pressure. The use of the pulmonary artery catheter allows for the determination of cardiac output and pulmonary vascular resistance. It is important to follow the pulmonary artery pressure in this setting because an increase in pulmonary artery pressure is often the cause of acute cor pulmonale and because serial measurements of pulmonary artery pressure and the pulmonary vascular resistance allow the effects of therapeutic interventions to be evaluated.

The right ventricular contractile state and volumes can be estimated by the rapid-response thermistor calculations of right ventricular ejection fraction (RVEF) using specialized pulmonary artery catheters. This device can measure beat-to-beat RVEF but is affected by tricuspid regurgitation and cardiac arrhythmias.

Perioperative TEE is increasingly useful in this patient population owing to the increasing numbers of trained individuals and equipment. Two-dimensional imaging of biventricular function and noninvasive estimates of right ventricular systolic pressure (using the modified Bernoulli equation) are examples of applications of TEE monitoring for patients with pulmonary hypertension.

Pulse oximetry and arterial blood gas sampling are simple ways of assessing pulmonary function. Capnography is not an accurate method of assessing PaCO₂ when significant dead space ventilation is present. The use of an indwelling arterial catheter facilitates arterial blood sampling. Calculation of intrapulmonary venous admixture by using mixed venous blood samples obtained from the pulmonary artery, however, is a more sensitive indicator of pulmonary dysfunction than PaO₂ values alone.

In the anesthetic management of patients with pulmonary hypertension and cor pulmonale, special consideration must be given to the degree of pulmonary hypertension, those factors that improve or worsen it, and the functional state of the right ventricle. For example, if pulmonary hypertension is coexistent with hypoxia in a patient with chronic bronchitis, administration of oxygen may afford significant relief of the pulmonary hypertension. If, however, the pulmonary hypertension is secondary to massive pulmonary fibrotic changes, little relief of pulmonary hypertension would be expected with the administration of oxygen. If the patient has an increase in blood viscosity, as in the polycythemia of chronic hypoxia, moderate hemodilution may be of some benefit in reducing the pulmonary vascular resistance if oxygen delivery can be maintained. When pulmonary hypertension is present without right ventricular failure, potent volatile anesthetics (which are pulmonary vasodilating in higher concentrations) may be the anesthetic drugs of choice. If, with high concentrations of potent volatile anesthetics, however, there is a decrease in hypoxic vasoconstriction, there is a theoretical risk of hypoxemia. Potent volatile agents or ketamine may also be indicated if pulmonary hypertension exists in patients who have pulmonary parenchymal disease with a significant bronchospastic component. In contrast to the volatile anesthetic agents, nitrous oxide might increase pulmonary artery pressure and should be used cautiously in this setting.^[119] In addition, factors that predispose to pulmonary vasoconstriction (e.g., hypoxia, hypercarbia, acidosis, hypothermia) should be avoided.^[120]

When pulmonary hypertension coexists with cor pulmonale, the anesthetic technique should attempt to preserve right ventricular function. Anesthetic drugs that may have been useful in pulmonary hypertension with preserved right ventricular function are now contraindicated because of their myocardial depressant effects. The primary concern is the maintenance of right ventricular function in the presence of an elevated right ventricular afterload. In this setting, a technique employing an opioid, such as fentanyl, in combination with sedative-hypnotic drugs, such as propofol or midazolam, probably provides the best cardiovascular stability.^[121]

Circulatory supportive measures in the setting of right ventricular failure do not differ in theory from measures employed in managing left ventricular failure ( Table 2-11 ). Important concerns are ventricular preload, heart rate, the inotropic state of the ventricle, and ventricular afterload. Right ventricular preload can be assessed by measurement of the central venous pressure. Preload can be augmented by judicious fluid infusion or decreased with a vasodilator, such as nitroglycerin, that primarily affects venous capacitance in low doses. Ventricular preload can also be reduced by initiation of positive-pressure ventilation.

TABLE 2-11 -- Abbreviated Pulmonary Vascular Pharmacopeia

Drug	PAP	PCWP	Q_p	SAP	HR	PVR
α and β Antagonists
Norepinephrine 0.05–0.5 μg/kg/min	↑	↑to ↑↑	—	↑↑	NC or ↑	↑
Phenylephrine 0.15–4 μg/kg/min	↑↑	—	↓	↑↑	↓	↑
Epinephrine 0.05-0.5 μg/kg/min	↑	NC or ↓	↑	↑↑	↑	↑
Dopamine 2–10 μg/kg/min	NC or ↑	NC or ↓	↑	NC or ↑	↑	↓
Dobutamine 5–15 μg/kg/min	↑	↓	↑↑	NC or ↑	↑	↓
Isoproterenol 0.015-0.15 μg/kg/min	SL ↓	↓	↑↑	↓	↑↑	↓
Vasopressin 2–8 units/hr	NC or ↑	↑	—^[†]	↑↑	NC or ↓	↑
β Antagonists
Propranolol 0.5–2.0 mg	—	NC to ↑	NC or ↓	NC or ↓	↓↓	NC or ↑
Esmolol 50–300 μg/kg/min	—	NC to ↑	NC or ↓	NC or ↓	↓↓	NC or ↑
α Antagonists
Phentolamine 1–3 μg/kg/min	↓	↓	↑	↓	↑	↓
Smooth Muscle Dilators
Sodium nitroprusside 0.5–3 μg/kg/min	↓	↓	↑↑	↓↓	↑	↓
Nitroglycerin 0.5–5 μg/kg/min	↓↓	↓	NC to ↑	↓	↑	↓
Prostaglandin E₁ 0.05–0.1 μg/kg/min	↓↓	↓	↑	↓	↑	↓
Adenosine 50–200 μg/kg/min	↓	↑	↑	NC or ↓	↑or ↓	↓
Phosphodiesterase III Inhibitors
Milrinone 0.375–0.75 μg/kg/min	↓	↓	↑	↓	↑	↓
Nitric oxide
1–80 ppm	↓↓	↑	↑↑	NC	NC	↓↓
Epoprostenol
(prostacyclin) 2–5 ng/kg/min IV	↓	NC	↑	↓	↑	↓
Iloprost
(stable prostacycline analog) 10–50 μg via nebulizer	↓↓	NC	↑↑	NC	NC	↓↓

^*Data not consistent, either NC, ↑ or ↓, most studies show less increase in PVR with norepinephrine compared with phenylephrine.

PAP, pulmonary artery pressure; PCWP, pulmonary capillary wedge pressure; Q_p, pulmonary blood flow; SAP, systemic arterial pressure; HR, heart rate;

PVR, pulmonary vascular resistance.

—, data unavailable; SL ↓, slight decrease; NC, no change.

^†	Vasopressin significantly decreases cardiac output.

Inotropic support is often required in the setting of right ventricular failure with chronic cor pulmonale. An inotropic agent should be selected only after considering its pulmonary effects, and the effects of the inotropic intervention should be monitored. Just as in left ventricular failure, where the reduction of left ventricular afterload can produce an increase in stroke volume and cardiac output, so in right ventricular failure, reduction in right ventricular afterload can produce similar effects.

Dobutamine or milrinone tend to reduce pulmonary artery pressure and pulmonary vascular resistance and would probably be the inotropic drugs of choice in right ventricular failure without systemic hypotension. If right ventricular perfusion pressures need to be maintained, or when right ventricular contractility is severely impaired, norepinephrine and epinephrine are the preferred catecholamines even in patients with pulmonary hypertension.^{[124] [125]} Furthermore, vasopressin is particularly effective for the treatment of systemic hypotension in patients with right ventricular failure. Vasopressin (antidiuretic hormone) is a posterior pituitary hormone that causes dose-dependent vasoconstriction and antidiuretic effects.^[124]

Vasodilators that have been found effective in reducing the afterload of the right ventricle include sodium nitroprusside, nitroglycerin, milrinone, adenosine, nifedipine, amlodipine, and prostaglandin E₁.^{[127] [128]} Inhaled nitric oxide selectively dilates the pulmonary vasculature and has been used to treat pulmonary hypertension in various clinical settings.^{[129] [130] [131]} Prostacyclin acts via specific prostaglandin receptors and has also been shown to reduce pulmonary hypertension.^[130] However, the vasodilatation is not selective for the pulmonary vasculature and systemic hypotension may ensue. Various newer prostacyclin analogs, such as epoprostenol, are now given for chronic pulmonary hypertension and may be useful for intraoperative use in the future. One caveat is that inadvertent discontinuation of chronic intravenous epoprostenol therapy may lead to a fatal pulmonary hypertensive crisis. The administration of prostacyclin and milrinone via inhalation has been described as a strategy to reduce systemic side effects.^[131] Inhaled prostaglandins are replacing inhaled nitric oxide in some institutions due to cost considerations.

As noted previously, the use of positive-pressure ventilation and positive end-expiratory pressure (PEEP) may produce a decrease in right ventricular preload. Positive-pressure ventilation may produce an increase in pulmonary artery pressure by physically reducing the cross-sectional area of the pulmonary vasculature during the inspiratory phase of ventilation. Before PEEP is instituted it must be remembered that the functional residual capacity is already increased in patients with chronic obstructive pulmonary disease and that the use of PEEP may have little to offer in terms of improving ventilation-perfusion matching.

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

CONSTRICTIVE PERICARDITIS AND CARDIAC TAMPONADE

Normal Pericardial Function

The pericardium is not essential to life, as is demonstrated from the benign effects of pericardiectomy. However, the pericardium normally provides resistance to overfilling of the ventricles in conditions such as tricuspid regurgitation, mitral regurgitation, or hypervolemic states. The intrapericardial pressure reflects intrapleural pressure and is a determinant of ventricular transmural filling pressure. The pericardium also serves to transmit negative pleural pressure, which maintains venous return to the heart during spontaneous ventilation.^[132]

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

Constrictive Pericarditis

Constrictive pericarditis results from fibrous adhesion of the pericardium to the epicardial surface of the heart ( Table 2-12 ). Its key feature is increased resistance to normal ventricular filling. Constrictive pericarditis is a chronic condition that is usually well tolerated by the patient until the disease is far advanced. Acute cardiac tamponade, in contrast, is a syndrome in which the onset of restrictive symptoms is rapid and dramatic.^{[135] [136] [137]}

TABLE 2-12 -- Conditions Producing Constrictive Pericarditis and Cardiac Tamponade

	Associated Cardiac Conditions
Constrictive Pericarditis
Idiopathic
Infectious
Can be sequela of most acute bacterial infections that produce pericarditis	Myocarditis
	Cardiomyopathy
Tularemia	Valve malfunction
Tuberculosis
Viral—especially arbovirus, coxsackievirus B
Mycotic	Valvular obstruction
Histoplasmosis
Coccidioidomycosis
Neoplastic
Primary mesothelioma of pericardium
Secondary to metastases—especially malignant melanoma
Physical causes
Radiation	Cardiomyopathy
Post-traumatic	Coronary artery disease
Postsurgical
Systemic syndromes
Systemic lupus erythematosus	Cardiomyopathy
	Coronary artery disease
Rheumatoid arthritis	Cardiomyopathy
	Coronary artery disease
	Aortic stenosis
Uremia	Cardiomyopathy
	Cardiac tamponade
Cardiac Tamponade
Infectious
Viral—most	Myocarditis
	Cardiomyopathy
	Valve malfunction
Bacterial—especially tuberculosis
Protozoal
Amebiasis
Toxoplasmosis
Mycotic infection	Valvular obstruction
Collagen disease
Systemic lupus erythematosus	Cardiomyopathy
	Coronary artery disease
	Constrictive pericarditis
Acute rheumatic fever
Rheumatoid arthritis	Cardiomyopathy
	Coronary artery disease
	Aortic stenosis
Metabolic disorders
Uremia
Myxedema	Low cardiac output
Hemorrhagic diatheses
Genetic coagulation defects
Anticoagulants
Drugs
Hydralazine
Procainamide (Pronestyl)
Phenytoin (Dilantin)
Physical causes
Radiation	Cardiomyopathy
	Coronary artery disease
	Constrictive pericarditis
Trauma (perforation)
Surgical manipulation
Intracardiac catheters
Pacing wires
Neoplasia
Primary—mesothelioma, juvenile xanthogranuloma
Metastatic
Miscellaneous
Postmyocardial infarction—ventricular rupture
Pancreatitis
Reiter's syndrome	Aortic regurgitation
Behçet's syndrome
Loeffler's syndrome—endocardial fibroelastosis with eosinophilia	Restrictive cardiomyopathy
Long-standing congestive heart failure

A number of characteristic hemodynamic features accompany constrictive pericarditis and pericardial tamponade. Rather than the slight respiratory variation in blood pressure seen in normal patients, dramatic respiratory variations in blood pressure (pulsus paradoxus) are present. Kussmaul's sign (jugular venous distention during inspiration) is present. With adequate blood volume, the right atrial pressure in constrictive pericarditis is usually equal to or greater then 15 mm Hg and usually equals the left atrial pressure. The pulmonary artery systolic pressure is usually less than 40 mm Hg, which helps to distinguish constrictive pericarditis from cardiac failure. Both constrictive pericarditis and cardiac tamponade demonstrate a diastolic “pressure plateau” or “equalization of pressures.” The right atrial pressure equals the right ventricular end-diastolic pressure, pulmonary artery diastolic pressure, and left atrial pressure. Early in the disease, cardiac output is normal, but with progression the cardiac output falls. Most symptoms are related to this fall in cardiac output or to the elevated venous pressure that develops in response to the decreased cardiac output and restriction of right ventricular filling.

Constrictive pericarditis often resembles a restrictive cardiomyopathy and occasionally presents a diagnostic dilemma. However, in contrast to constrictive pericarditis, cardiac output in a restrictive cardiomyopathy is decreased primarily, left atrial pressure is increased, mean pulmonary artery pressure is increased, and there is no pulsus paradoxus.^{[138] [139] [140] [141]}

Because constrictive pericarditis restricts ventricular diastolic filling, normal ventricular end-diastolic volumes are not obtained and stroke volume is decreased. Compensatory mechanisms include an increase in heart rate and contractility, which usually occur secondary to an increase in endogenous catecholamine release. This maintains cardiac output in the presence of the restricted stroke volume until the decrease in ventricular diastolic volume is quite severe. As cardiac output falls there is decreased renal perfusion. This results in increased levels of aldosterone, with a resultant increase in extracellular volume. The increase in extracellular volume increases right ventricular filling pressure, which eventually becomes essential for maintaining ventricular diastolic volume in the presence of severe pericardial constriction.

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

Cardiac Tamponade

Cardiac tamponade, like constrictive pericarditis, also restricts ventricular diastolic filling, but it is caused by extrinsic compression of the ventricular wall from fluid in the pericardium. Symptoms of cardiac tamponade are usually rapid in onset but depend on the rate and volume of pericardial fluid accumulation. With rapid fluid accumulation in the pericardium, a small volume can produce symptoms.^[140] With a more gradual accumulation of fluid, the pericardium stretches, and larger pericardial volumes are tolerated before symptoms occur. Once symptoms begin, however, they proceed rapidly because of the sigmoidal relationship between pressure and volume in the pericardial sac. As the limit of pericardial distensibility is reached, small increases in volume produce dramatic increases in intrapericardial pressure. As such, removal of small volumes of pericardial fluid in a situation of severe cardiac tamponade can produce very dramatic relief of symptoms as a result of a rapid fall in intrapericardial pressure.^[141]

The clinical features of cardiac tamponade result from restriction of diastolic ventricular filling and increased pericardial pressure. The increased pericardial pressure is transmitted to the ventricular chamber. This decreases the AV pressure gradient during diastole and impedes ventricular filling. Thus, there is a decrease in the end-diastolic ventricular volume and stroke volume. Increased diastolic ventricular pressure decreases coronary perfusion pressure and also results in early closure of the mitral and tricuspid valves, limiting diastolic flow and reducing ventricular volume. Figure 2-5 provides a diagrammatic summary of the pathophysiology of cardiac tamponade. The compensatory mechanisms in cardiac tamponade are similar to those in constrictive pericarditis. A decrease in cardiac output results in an increase in endogenous catecholamines. The consequent increases in heart rate and contractility help maintain cardiac output in the presence of a decreased stroke volume. Increased contractility increases the ejection fraction, allowing more complete ventricular emptying. Echocardiography will differentiate cardiac tamponade from constrictive pericarditis. Right ventricular and/or right atrial collapse is the echocardiographic hallmark of tamponade.^[142]



FIGURE 2-5 Schematic of physiology of tamponade.

Cardiac tamponade can be seen in blunt chest trauma when there is rupture of a cardiac chamber. However, the most common cardiac involvement in blunt chest trauma is cardiac contusion. Cardiac contusion may mimic an evolving myocardial infarction, and specific markers for cardiac injury, such as troponin T and troponin I, are increased in both conditions. Blunt chest trauma may also result in tricuspid regurgitation from a ruptured papillary muscle, traumatic ventricular septal defect, and dissection or interruption of the aorta.^[143]

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

Anesthetic Considerations

Monitoring should be aimed at the compensatory mechanisms in constrictive pericarditis and cardiac tamponade. The electrocardiogram should be observed for heart rate and ischemic changes, because the myocardial oxygen supply/demand ratio can be altered by the pathologic process and also by therapeutic interventions. Filling pressures should also be assessed. The decision to use a pulmonary artery catheter or a central venous pressure catheter is based on the following: (1) the state of ventricular function; (2) the surgical procedure; and (3) the postoperative monitoring requirements. Central venous pressure monitoring is indicated in the following instances: (1) if cardiac tamponade is superimposed on an otherwise normal ventricle, as in trauma; (2) if the surgical procedure is only drainage of the tamponade fluid and an exploration of the pericardium in an effort to determine the cause of the tamponade (here the central venous pressure will adequately indicate the relief of cardiac tamponade); and (3) if postoperative monitoring is only aimed at following the potential reaccumulation of pericardial fluid. The central venous pressure is probably more sensitive than the pulmonary capillary wedge pressure in diagnosing reaccumulation of pericardial fluid.

The right ventricle has a very steep Starling curve with a relatively narrow range of filling pressures, which are lower than those of the left ventricle ( Fig. 2-6 ). The filling pressures that would indicate reaccumulation of pericardial fluid are more widely divergent from the normal right ventricular filling pressures than they are from the filling pressures of the left ventricle. Accordingly, monitoring right ventricular filling pressures is a more sensitive indicator of developing tamponade. On the other hand, in chronic cardiac tamponade coupled with a cardiomyopathy, or in constrictive pericarditis of any cause, the pulmonary artery catheter probably provides more useful information. During a pericardiectomy, the pulmonary artery catheter is useful in assessing myocardial depression occurring secondary to cardiac manipulation and in assessing the volume status of the patient. Postoperative monitoring must address both the problems of reaccumulation of pericardial fluid and of the development of overt ventricular failure in patients with an underlying cardiomyopathy. Intra-arterial monitoring is nearly universally indicated in symptomatic constrictive pericarditis and pericardial tamponade.



FIGURE 2-6 Right and left ventricular function curves where left or right ventricular stroke work index (LVSWI or RVSWI, respectively) is plotted as a function or right or left ventricular end-diastolic pressure (RVEDP or LVEDP, respectively).

Two-dimensional echocardiography is well suited to monitoring patients with constrictive pericarditis or tamponade. Intraoperatively, this can be performed with a transesophageal probe. According to the “Practice Guidelines for Perioperative Transesophageal Echocardiography” published by the American Society of Anesthesiologists and the Society of Cardiovascular Anesthesiologists, the detection of pericardial effusions or evaluation of pericardial surgery is a category II indication for intraoperative TEE monitoring. The intraoperative evaluation of adequate drainage in patients undergoing pericardial window procedures is classified as a category I indication. Qualitative estimation of the degree of tamponade, localization of effusions, quantitative estimation of ejection fraction, and right- and left-sided preload conditions may be obtained with this technology.

The similar pathophysiology of cardiac tamponade and constrictive pericarditis create similar approaches for circulatory support. Cardiovascular support may be required before definitive therapy in either condition, but especially in cardiac tamponade. Circulatory therapy should be directed toward the three main compensatory mechanisms in these conditions: (1) maintenance of adequate ventricular filling; (2) maintenance of heart rate; and (3) maintenance of myocardial contractility. Intravascular volume maintenance is critical in these conditions, and a decline in filling pressures can result in dramatic decreases in cardiac output. Because an increased heart rate maintains the cardiac output in the presence of a decreased stroke volume, β-agonists are the inotropic drugs of choice because they increase the heart rate and contractility. Direct α-adrenergic agonists such as phenylephrine are contraindicated, because they increase SVR and usually decrease heart rate because of baroreceptor reflexes. With the use of inotropic drugs, such as epinephrine and dopamine, myocardial contractility is also maintained, contributing to homeostasis by increasing ejection fraction.

The first step in the anesthetic management of cardiac tamponade is to assess its severity. The anesthesiologist must decide whether induction of anesthesia can be tolerated. If the patient is tachycardic and hypotensive, with high filling pressures, pericardiocentesis or a pericardial window performed under local anesthesia is probably needed before the induction of general anesthesia. After the partial relief of severe cardiac tamponade, cardiac function should be reassessed. Usually, the hemodynamic situation is markedly improved. In the case of less severe symptoms, it is reasonable to induce general anesthesia using a reduced dosage of intravenous ketamine (0.25 to 1.0 mg/kg) or etomidate. Thiopental and propofol are relatively contraindicated because they may produce dramatic hypotension due to venodilation. High-dose narcotic anesthesia will not depress myocardial contractility, but the associated bradycardia may not be tolerated. The tachycardia associated with the use of pancuronium may be advantageous in maintaining circulatory homeostasis but should be used with caution in patients whose renal function is impaired by prerenal failure.^{[146] [147] [148] [149]}

In the presence of restricted ventricular diastolic filling, the initiation of positive-pressure ventilation may severely decrease venous return. When this occurs, intravascular volume must be increased in an effort to increase the ventricular filling pressure. After the relief of tamponade, the physiologic situation tends to revert to normal and further anesthetic requirements will then depend on the degree of cardiac manipulation by the surgeon during exploration of the pericardium (e.g., bleeding from a coronary graft may be the cause of the tamponade).

In constrictive pericarditis the altered physiology remains throughout most of the surgical procedure, whereas in cardiac tamponade the altered physiology is often rapidly relieved by opening the pericardium. The features of anesthetic management are similar to those of unrelieved cardiac tamponade: maintaining the intravascular volume, heart rate, and myocardial contractility. In this setting, similar anesthetic techniques are also used but a number of special problems may arise in the patient who comes to surgery for pericardiectomy. Arrhythmias, often requiring medical therapy, are quite frequent with the dissection of the adherent pericardial sac away from the ventricular epicardial surface. Rapid changes in filling pressures with cardiac manipulation occur. Thus, it is important for the anesthesiologist to be in constant communication with the surgeon concerning the hemodynamic response to the various manipulations of the heart. During pericardiectomy, with frequent episodes of hypotension, it is often difficult to distinguish relative hypovolemia and transient myocardial depression that occur with cardiac manipulation from incipient myocardial failure. Here the pulmonary artery catheter or TEE is particularly useful in distinguishing between hypotension due to hypovolemia and hypotension secondary to myocardial failure.^[148]

Pericardiectomy is frequently associated with bleeding and coagulation problems. During the procedure there is a continued oozing of blood from the raw pericardial and epicardial surfaces that often necessitates transfusion. If the patient will not tolerate the severe cardiac manipulation, cardiopulmonary bypass with systemic heparinization is required for circulatory support during the procedure, particularly during the dissection on the posterior cardiac surface. If cardiopulmonary bypass and heparinization are required, then the coagulation problems become very complex. Platelet concentrates, fresh frozen plasma, and cryoprecipitate may be required if the bleeding is massive. These bleeding problems often continue after heparin reversal by protamine. Prophylactic therapy with lysine analog antifibrinolytics (ε-aminocaproic acid or tranexamic acid) or aprotinin should be considered. Even without the use of cardiopulmonary bypass, postoperative mechanical ventilation is probably the safest method of managing the post-pericardiectomy patient with multiple intraoperative problems such as continued bleeding, arrhythmias, and myocardial injury and depression.

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

UNCOMMON CAUSES OF VALVULAR LESIONS

The normal function of the cardiac valves is to maintain one-way forward flow during the cardiac cycle. Valvular lesions interfere with this function either by producing obstructions to forward flow or by allowing varying degrees of backward flow. This section will consider the pathophysiology of uncommon causes of valvular lesions and how these diseases affect cardiac compensatory mechanisms.

Lesions producing valvular stenosis are usually graded on the basis of valve area, which is normally calculated using echocardiography or by cardiac catheterization (using the Gorlin formula).^[149] Flow is also influenced by such factors as blood viscosity and turbulence across the valve. Regurgitant lesions are usually evaluated on an ordinal scale by echocardiography or at angiography, based on the rate of dye clearance. Scales of 1+ through 4+, or estimations of mild, moderate, or severe, are common descriptors.^{[152] [153] [154]} Effective regurgitant orifice of the mitral valve can be calculated by echocardiography in many patients, providing a more quantitative estimate of mitral regurgitation.

Rheumatic valvular lesions often exist as isolated defects in a relatively normal cardiovascular system, and they can be present for extended periods without symptoms. In contrast, the uncommon diseases considered here produce valvular lesions that are usually not associated with an otherwise normal circulatory system, because these lesions frequently occur in the setting of cardiomyopathy, pulmonary hypertension, cor pulmonale, or coronary artery disease. The asymptomatic period in rheumatic lesions is related to the effectiveness of intrinsic cardiovascular compensatory mechanisms, and symptoms begin only when these compensatory mechanisms fail. With the diseases considered in this section, the normal methods of compensation are often severely compromised. Because anesthetic management of valvular lesions is directed at preserving the compensatory mechanisms, it is essential to understand how these diseases interfere with compensation and how anesthetic manipulations interact with them.

Aortic Stenosis ( Table 2-13A )

Aortic stenosis results from a narrowing of the aortic valve orifice, with a pressure gradient across this narrow orifice. The obstruction to flow is proportional to the decrease in cross-sectional area of the obstructed outlet. The left ventricle compensates by increasing the transvalvular pressure to maintain flow. The ventricle undergoes concentric hypertrophy in order to force blood across the stenotic valve but suffers a decrease in compliance. As a result of hypertrophy, ventricular wall tension per unit area is decreased but total ventricular oxygen demand is increased because of an increase in left ventricular mass. Another method of compensation for aortic stenosis is an increase in ventricular ejection time that decreases the turbulent flow across the valve, thus decreasing flow resistance and allowing for more complete ventricular emptying.

TABLE 2-13A -- Uncommon Causes of Valvular Lesions

Features Affecting Compensatory Mechanisms

Disease

Atrial Transport and Rhythm

Contractility and Hypertrophy

Associated Problems

Aortic Stenosis (AS)

Congenital and degenerative diseases

Congenital

(1)

Valvular

(2)

Discrete subvalvular

(3)

Supravalvular

Bicuspid valve

Coarctation of aorta, polycystic kidneys

Degenerative

(1)

Senile calcification

(2)

Mönckeberg sclerosis

Infectious diseases

Syphilis

Dilated cardiomyopathy and outflow obstruction

Actinomycosis

Dilated cardiomyopathy and outflow obstruction

Infiltrative diseases

Amyloidosis

Sinoatrial and atrioventricular nodal infiltration

Dilated cardiomyopathy

Coronary artery disease

Pompe's disease

Hypertrophic cardiomyopathy

Dilated cardiomyopathy

Fabry's disese

Cardiomyopathy

Hypertension

Primary xanthomatosis

Atrial arrhythmias with rapid rate

Dilated cardiomyopathy

Coronary artery disease

Miscellaneous

Sarcoid

Arrhythmias and inflammation of conduction system

Left ventricular dyssynergy with aneurysm

Left ventricular infiltration and cardiomyopathy

Endocardial fibroelastosis

Restriction of ventricular filling

Mitral valve malfunction with stenosis producing poor ventricular filling

Interference with subendocardial blood flow with decreased oxygen delivery to myocardium

Regurgitation decreasing left ventricular pressure development

Methysergide

Restriction of ventricular filling secondary to endocardial fibrosis

Similar to endocardial fibrosis

Paget's disease

Arrhythmias with loss of atrial kick

Possible mitral stenosis and poor ventricular filling

Complete heart block

Pulmonary Stenosis (PS)

Congenital

Valvular

Infundibular

Supravalvular with peripheral coarctation

Genetic—Noonan's syndrome

Hypertrophic cardiomyopathy— obstructive and nonobstructive

Aortic regurgitation

Infiltrative diseases

Pompe's

Arrhythmias secondary to conduction system infiltration

Dilated cardiomyopathy

Aortic stenosis and outflow tract obstruction

Lentiginosis

Massive atrioventricular septal hypertrophy

Sarcoid

Arrhythmias secondary to conduction system involvement

Cardiomyopathy

Cor pulmonale

Infectious

Subacute bacterial endocarditis

Heart block

Tricuspid insufficiency

Tuberculosis

Pulmonary insufficiency

Rheumatic fever

Usually associated with other valvular lesions

Neoplastic

Mediastinal tumors

Primary tumors

1) Sarcoma

Rhythm or cardiomyopathic complications will depend on extent of wall involvement in the neoplastic process

2) Myxoma

Malignant carcinoid syndrome

Endocardial fibrosis

Pulmonary hypertension

Pulmonary regurgitation

Tricuspid regurgitation and/or stenosis

Physical—extrinsic causes

Aneurysm of ascending aorta or sinus of Valsalva

Constrictive pericarditis

Picture of restrictive cardiomyopathy but usually with good ventricular function

Postsurgical banding

Often associated with other congenital cardiac abnormalities

As ventricular compliance falls, passive filling of the ventricle during diastole is decreased and the ventricle becomes increasingly dependent on atrial augmentation of ventricular diastolic volume. In this setting, the atrial “kick” may contribute as much as 30% to 50% to the left ventricular end-diastolic volume. There is increased intraventricular systolic pressure that virtually eliminates systolic coronary flow. Diastolic subendocardial blood flow also decreases as a result of a lower coronary perfusion pressure. Aortic diastolic pressure must remain high to maintain adequate myocardial blood flow.^{[155] [156]}

It should now be considered how an uncommon disease process might affect compensatory mechanisms. First, a disease could potentially interfere with the compensatory mechanism of concentric hypertrophy and increased ventricular contractility. In Pompe's disease, left ventricular hypertrophy occurs but is secondary to massive myocardial glycogen accumulation; and for this reason the ventricular strength is not increased to compensate for the outflow tract obstruction that commonly occurs in this disease. Another example would be amyloidosis in which aortic stenosis is coupled with a restrictive cardiomyopathy. Here, as in Pompe's disease, there is an inability to increase either ventricular muscle mass or contractility. A disease process may also interfere with the critical atrial augmentation of ventricular end-diastolic volume as, for example, in sarcoidosis or Paget's disease. Diseases of this type infiltrate the cardiac conduction system, resulting in arrhythmias or heart block with the loss of synchronous atrial contraction. The requirement for elevated ventricular diastolic filling pressure may be compromised in a situation, such as methysergide toxicity, that can produce mitral stenosis coupled with aortic stenosis. This reduces both passive ventricular filling and ventricular filling resulting from atrial contraction.

Diseases that affect the conduction system in addition to producing loss of atrial contraction can also produce tachyarrhythmias, which decrease ventricular ejection time and increase turbulent flow across the valves. Table 2-13A lists causes of aortic stenosis and key features of their pathophysiology that can adversely affect cardiac compensatory mechanisms.

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

Pulmonic Stenosis (see Table 2-13A )

As in aortic stenosis, the valve area is the critical determinant of transvalvular blood flow. Pulmonic stenosis produces symptoms that are similar to the classic clinical features of aortic stenosis: fatigue, dyspnea, syncope, and angina. The compensatory mechanisms in pulmonic stenosis are similar to those in aortic stenosis. Initially, under the stress of right ventricular outflow obstruction, the right ventricle dilates. However, it eventually undergoes concentric hypertrophy and changes from a crescent-shaped chamber best suited to handle volume loads to an ellipsoidal chamber best suited to handle pressure loads. Second, there is an increase in ejection time, maintained with a slow heart rate. Third, increases in ventricular filling pressure occur as a result of an increase in intravascular volume and a change in the compliance of the right ventricle.

The presence of angina, which occurs occasionally in pulmonic stenosis, should especially be noted. Usually, the right ventricle is a thin-walled chamber with low intraventricular pressures. This normal situation results in a high transmural perfusion pressure and good subendocardial blood flow that limits development of ischemia of the right ventricle. Concentric hypertrophy increases both right ventricular mass and right ventricular pressures, increasing the potential for ischemia of the right ventricle, since right ventricular oxygen requirements are increased and coronary perfusion may be decreased. Cyanosis can occur with severe pulmonic stenosis accompanied by a low, fixed cardiac output. When right ventricular pressure rises, a patent foramen ovale may produce right-to-left interatrial shunting. Usually, isolated pulmonic stenosis is well tolerated for long periods until compensatory mechanisms fail. When a second valvular lesion coexists with pulmonic stenosis, the potential effects of this lesion on compensatory mechanisms should be considered.^[155]

Compensatory mechanisms in pulmonic stenosis can be altered in much the same way as in aortic stenosis. Decreases in right ventricular contractility occur in infiltrative diseases of the myocardium, such as Pompe's disease or sarcoidosis. The loss of the atrial “kick” and the development of tachyarrhythmias have the same implications for cardiac function in pulmonic stenosis as in aortic stenosis. In subacute bacterial endocarditis, tricuspid insufficiency may coexist with pulmonic stenosis, producing an impairment of pressure development in the right ventricle, especially when right ventricular failure supervenes. With the increase in right ventricular mass and the increased requirement for oxygen delivery to the right ventricle, the possibility should be considered that oxygen supply might be compromised, as in the coronary artery pathology of Pompe's disease.

Many of these patients are candidates for balloon valvuloplasty of the pulmonary valve. In this procedure, a balloon catheter is placed percutaneously and the tip is guided across the pulmonic valve. The balloon is inflated, tearing the fused leaflets apart.^[156] A period of severe hypotension occurs during balloon inflation, and transient loss of consciousness, vomiting, and seizures may occur. Pulmonic regurgitation is invariably produced, but this is usually well tolerated hemodynamically. This procedure has reduced the number of patients presenting for operative valvuloplasty and valve replacement, although there are limited data on the long-term outcome for these patients.^[157] In many institutions, anesthesiologists provide monitored care for these patients. Balloon valvuloplasty is also used for selected patients with aortic and mitral stenosis.

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

Aortic Insufficiency ( Table 2-13B )

The primary problem in aortic insufficiency is a decrease in net forward blood flow from the left ventricle from diastolic regurgitation of blood back into the left ventricular chamber. The first question to ask in the setting of aortic insufficiency is whether the condition is acute or chronic, because this is often the main determinant of the degree of compensation. Aortic insufficiency represents an almost pure volume overload of the left ventricular chamber. The left ventricle responds initially with dilation to maximize the effects of increases in fiber length. Acutely, this may result in heart failure, because the increased ventricular diameter increases wall tension and end-diastolic pressure. An acute increase in ventricular volume may also compromise the anchoring of the mitral valve by changing the geometric relationship of the papillary muscles, resulting in mitral regurgitation and pulmonary edema.^[158]

TABLE 2-13B -- Uncommon Causes of Valvular Lesions

Features Affecting Compensatory Mechanism

Disease

Left Ventricular Compliance and Contractility

Heart Rate and Rhythm

Vascular Resistance

Associated Cardiovascular Abnormalities

Aortic Insufficiency

Infiltrative disease

Amyloidosis

Dilated and restrictive cardiomyopathy

Arrhythmias with infiltration of conduction system

Coronary artery disease

Stenosis or insufficiency of other valves

Morquio's

Usually isolated aortic insufficiency with mild mucopolysaccharidosis

Scheie's

Pseudoxanthoma elasticum

Dilated cardiomyopathy

Infectious disease

Bacterial endocarditis

Complete heart block

Insufficiency of other valves

Syphilis

Dilated or restrictive cardiomyopathy

Infiltration of conduction system

Aortic stenosis

Aortic aneurysm

Rheumatic fever

Congenital valve disease

Bicuspid aortic valve

Aneurysm of sinus of Valsalva

Usually intact compensatory mechanisms

Congenital fenestrated cusp

Degenerative

Marfan's

Normal

Cystic medial necrosis of aorta with dissection

Pulmonic insufficiency

Osteogenesis imperfecta

Normal

Cystic medical necrosis

Mitral regurgitation

Inflammatory

Mitral regurgitation

Relapsing polychondritis

Systemic lupus erythematosus

Pericarditis and effusion

Hypertension secondary to renal disease

Mitral regurgitation

Reiter's syndrome

Rheumatoid arthritis

Congestive cardiomyopathy

Complete heart block

Aortic stenosis

Mitral stenosis and/or insufficiency

Constrictive pericarditis

Cardiac tamponade

Systemic syndromes

Ankylosing spondylitis

Complete heart block

Aortic dissection

Cogan's syndrome

Coronary artery disease

Generalized angiitis

Dilated cardiomyopathy

Noonan's syndrome

Cardiomyopathy

Pulmonic stenosis

Ehlers-Danlos

Spontaneous vascular dissection

Miscellaneous causes

Aortic dissection

Interference with compensation depends on cause, e.g., syphilis, Marfan's, traumatic

Methysergide

Endocardial fibrosis—restriction of left ventricular filling

Mitral valve stenosis and/or insufficiency

Traumatic rupture

Acute dilatation and failure

Pulmonic Insufficiency

Congenital

Isolated

(1)

Hypoplastic

Usually tolerated as isolated lesion

(2)

Aplastic

(3)

Bicuspid

Associated with other congenital cardiac lesions

Toleration of pulmonic insufficiency depends on degree of myocardial dysfunction induced by other cardiac lesions

Acquired

Syphilitic aneurysm of pulmonary artery

Dilated cardiomyopathy

Infiltration of conduction system

Luminal narrowing

Rheumatic

Tolerated well in isolation

Bacterial endocarditis

Complete heart block

Endocarditis of other valves

Echinococcus cyst

Endocardial fibrosis

Tricuspid valve malfunction

Malignant carcinoid syndrome

Endocardial fibrosis

Tricuspid valve malfunction

Physical

Traumatic

After valvotomy/valvuloplasty for pulmonic stenosis

Decreased ventricular compliance if right ventricle is hypertrophic from pulmonic stenosis

Functional—secondary to pulmonary hypertension

Ventricular hypertrophy with decreased compliance

Elevated pulmonary resistance due to pulmonary hypertension

Chronic obstructive pulmonary disease

Mitral stenosis

Primary pulmonary hypertension

In chronic aortic insufficiency, however, a number of compensatory changes minimize the degree of diastolic regurgitation. The first compensatory mechanism is an increase in left ventricular chamber size with eccentric hypertrophy. The left ventricular compliance is increased, which produces an increase in volume at the same filling pressure, thus reducing end-diastolic pressure and wall tension. The increase in ventricular volume allows full use of the Frank-Starling mechanism, whereby the strength of ventricular contraction is increased with increasing fiber length. Ejection fraction is maintained, because both stroke volume and ventricular end-diastolic volume increase together. Despite these compensatory mechanisms, however, a number of studies have shown that ventricular contractility is depressed.^[159] Nevertheless, the onset of clinical symptoms of aortic insufficiency does not necessarily correlate with ventricular function status.^[160]

In contrast to aortic stenosis, the augmentation of ventricular end-diastolic volume by the atrial contraction is not essential to ventricular compensation in aortic insufficiency. A rapid heart rate seems to be advantageous in aortic insufficiency, because the rapid heart rate in aortic insufficiency reduces the time for diastolic filling and helps prevent diastolic overdistention of the ventricle from regurgitant flow. In aortic insufficiency, the amount of regurgitant flow increases as SVR increases. Thus, the third major compensatory mechanism in aortic insufficiency is the maintenance of a low peripheral resistance, because forward flow in aortic insufficiency is inversely proportional to the SVR.

The increase in chamber size and eccentric hypertrophy, which help maintain cardiac function in aortic insufficiency, can be compromised in such conditions as ankylosing spondylitis in which myocardial fibrosis limits the increase in chamber size to the degree that this disease produces a restrictive picture. Cogan's syndrome produces a generalized cardiomyopathy with coronary artery disease and can alter the compensatory mechanism by decreasing both the ability of the left ventricle to hypertrophy and that of the coronary arteries to deliver oxygen to the ventricle. Increases in left ventricular compliance could be prevented in situations such as aortic insufficiency produced by methysergide, which produces an endocardial fibrosis and thus decreased ventricular compliance. The usual ability of the left ventricle to maintain the ejection fraction in aortic insufficiency could be compromised by the cardiomyopathy of amyloidosis. The aortic insufficiency produced by acute bacterial endocarditis is occasionally associated with complete heart block, resulting in a slow heart rate with ventricular overdistention and a decrease in cardiac output. Aortic insufficiency due to conditions such as SLE associated with increased peripheral resistance can increase the regurgitant fraction in the presence of the incompetent aortic valve.^{[163] [164]}

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

Pulmonic Insufficiency (see Table 2-13B )

Pulmonic insufficiency usually occurs in the setting of pulmonary hypertension or cor pulmonale but may exist as an isolated lesion, as in acute bacterial endocarditis in intravenous drug users. It may also be iatrogenic, because it frequently is a sequela of pulmonary valvuloplasty procedures. Pulmonic insufficiency is extremely well tolerated for long periods of time. Like aortic insufficiency, it represents a volume overload on the ventricular chamber, but the crescentic right ventricular geometry is such that volume loading is easily handled. Compensatory mechanisms for pulmonic insufficiency are the same as for aortic insufficiency: an increase in right ventricular compliance, rapid heart rate, and low pulmonary vascular resistance. The right ventricle is normally a highly compliant chamber; and with its steep filling pressure-stroke volume curve, it functions very well in the presence of volume increases.

The degree of pulmonic regurgitation is determined by the pulmonary arterial diastolic to right ventricular end-diastolic pressure gradient. For this reason, low pulmonary vascular resistance and low left-sided filling pressure are essential to maintaining forward flow. In general, there is less increase in ventricular end-diastolic volume than in aortic insufficiency. The ejection fraction, however, is not as well maintained in pulmonic insufficiency as it is in aortic insufficiency. With severe pulmonic regurgitation, as in aortic insufficiency, eccentric hypertrophy of the ventricular chamber occurs.^[163]

Disease states can interfere with the compensatory mechanisms of the right ventricle in several ways. Diseases that produce pulmonic insufficiency, such as the malignant carcinoid syndrome, also produce an endocardial fibrosis that decreases the ability of the right ventricular chamber to dilate in response to volume loading. Increases in right ventricular afterload increase the regurgitant fraction. This is especially true when pulmonic insufficiency is secondary to pulmonary hypertension. Hypoxemia can increase pulmonary vascular resistance as in the hypoxemia that results from pulmonary vascular dysfunction in carcinoid syndrome. It is unusual for a cardiomyopathy to coexist with isolated pulmonic insufficiency; thus the potential for eccentric hypertrophy is usually left intact. However, syphilis could present a situation in which a cardiomyopathy exists along with pulmonic insufficiency, although this would depend on the extent of syphilitic involvement of the myocardium.

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

Mitral Stenosis ( Table 2-13C )

The primary defect in mitral stenosis is a restriction of normal left ventricular filling across the mitral valve. As in other stenotic lesions, the area of the valve orifice is the key to flow; and, as the orifice gets smaller, turbulent flow increases across the valve and total resistance to flow increases. The important features in compensation of mitral stenosis are (1) increasing the pressure gradient across the valve and (2) prolonging the duration of diastole. The compensatory mechanisms in mitral stenosis include (1) dilation and hypertrophy of the left atrium, (2) increases in atrial filling pressures, and (3) a slow heart rate to allow sufficient time for diastolic flow with minimal turbulence.^[164]

TABLE 2-13C -- Uncommon Causes of Valvular Lesions

Features Affecting Compensatory Mechanisms

Disease

Rhythm

Atrial Transport

Left Ventricular Function

Associated Conditions

Mitral Stenosis

Inflammatory

Rheumatic fever

Rheumatoid arthritis

Heart block

Pericardial constriction

Dilated cardiomyopathy

Aortic stenosis and insufficiency

Cardiac tamponade

Mitral insufficiency

Infiltrative

Amyloidosis

Heart block

Atrial dilatation and hypertrophy

Dilated and restrictive cardiomyopathy

Malfunctioning of other valves

Infiltration of conduction system

Sarcoidosis

Infiltration of conductionx system

Dilated cardiomyopathy

Pulmonary hypertension

Gout

Infiltration of conduction system

Cor pulmonale

Miscellaneous

Left atrial myxoma

Parachute mitral valve

Concentric ring of left atrium

Normal compensatory mechanism

Methysergide

Endocardial fibrosis

Mitral insufficiency

Wegener's granulomatosis

Arrhythmias secondary to myocardial vasculitis

Myofibrillar degeneration

Dilated cardiomyopathy

B. Tricuspid Stenosis

Inflammatory

Rheumatic fever

Usually associated with other valvular lesions

Systemic lupus erythematosus

Arrhythmias secondary to pericarditis

Coronary artery disease

Cardiomyopathy

Fibrotic

Carcinoid syndrome

Fibrosis evolving to hypertrophy and dilatation

Pulmonary hypertension with increased right ventricular afterload

Pulmonic stenosis

Endocardial fibrosis

Endocardial fibroelastosis

Similar to carcinoid syndrome

Methysergide

Similar to carcinoid syndrome

Mitral and aortic valvular adnormality

Miscellaneous

Hurler's syndrome

Infiltration of conduction system

Infiltration of atrial wall

Dilated cardiomyopathy

Aortic stenosis

Myxoma of right atrium

Usually normal compensatory mechanisms

Decompensation in rheumatic mitral stenosis usually occurs when there is atrial fibrillation with a rapid ventricular rate. This causes a loss of the atrial contraction and decreased time for ventricular filling, which results in pulmonary vascular engorgement. Thus, altered left ventricular function is usually not the limiting factor in the ability of the heart to compensate for mitral stenosis.^[165]

As in other valvular lesions produced by uncommon diseases, coexistent cardiovascular problems that interfere with compensatory mechanisms are very important. Diseases such as sarcoidosis or amyloidosis can infiltrate ventricular muscle, preventing left ventricular filling by decreasing compliance. Amyloidosis, gout, and sarcoidosis can also affect the conduction system of the heart, resulting in heart block, tachyarrhythmias, or atrial fibrillation.

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

Tricuspid Stenosis (see Table 2-13C )

Tricuspid stenosis is usually associated with mitral stenosis as a sequela of rheumatic fever. Usually the other valve lesions associated with tricuspid stenosis determine heart function and the tricuspid stenosis often exists as an almost incidental lesion. Isolated tricuspid stenosis is very rare, and the etiology is either carcinoid or congenital. The problems in tricuspid stenosis are similar to those in mitral stenosis. There is a large right atrial to right ventricular diastolic gradient, and flow across the stenotic tricuspid valve is related to valve area.^{[168] [169]}

The compensatory mechanisms in tricuspid stenosis are also similar to those in mitral stenosis. An increase in right atrial pressure maintains flow across the stenotic valve, and this is associated with hepatomegaly, jugular venous distention, and peripheral edema. Also, the heart compensates with right atrial dilatation and hypertrophy and increases in the strength of atrial contraction, improving the atrial transport of blood across the stenotic valve. The implications of slow heart rate in tricuspid stenosis are the same as in mitral stenosis. Ventricular contractility is usually well maintained. The onset of atrial fibrillation in tricuspid stenosis is a less crucial event than in mitral stenosis. In tricuspid stenosis it may produce symptoms such as an increase in peripheral edema, whereas in mitral stenosis it results in signs of left-sided failure.^[168]

Diseases can interfere with cardiac compensation for tricuspid stenosis in much the same way as they can interfere with cardiac compensation for mitral stenosis. There may be further restriction of right ventricular filling in conditions such as malignant carcinoid syndrome that produce an endocardial fibrosis that reduces right ventricular compliance. Tricuspid stenosis frequently coexists with pulmonic stenosis in the carcinoid syndrome, resulting in a severe restriction of cardiac output.^[169]

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

Mitral Regurgitation ( Table 2-13D )

Mitral regurgitation, like aortic regurgitation, results from failure of the affected valve to maintain competence during the cardiac cycle. Mitral regurgitation occurs by one of three basic mechanisms: (1) damage to the valve apparatus itself; (2) inadequacy of the chordae tendineae– papillary muscle support of the valvular apparatus; or (3) left ventricular dilation and stretching of the mitral valve annulus with a loss of the structural geometry required for valvular closure.^[170] Mitral regurgitation represents a volume overload of both the left atrium and the left ventricle, producing as much as a fourfold to fivefold increase in ventricular end-diastolic volume. In mitral regurgitation, ventricular ejection is usually well preserved because of the parallel unloading circuit through the open mitral valve, which allows a rapid reduction of wall tension in the ventricle during systole. However, the volume overload results in an irreversible decrease in contractility. Ironically, mitral regurgitation serves as its own protective afterload reduction system.^[171]

TABLE 2-13D -- Uncommon Causes of Valvular Lesions

Features Affecting Compensatory Mechanisms

Disease

Rate

Left Ventricular Function and Compliance

Vascular Resistance

Associated Conditions

A. Mitral Regurgitation (MR)

Conditions producing annular dilatation

Aortic regurgitation

Usually in failure at this stage

Elevated with low output

Left ventricular failure

Usually elevated

Conditions affecting the chordae tendineae and papillary muscles

Myocardial ischemia

Associated arrhythmias, especially bradyarrhythmias

Often poor

Normal or elevated if cardiac output decreased

Chordal rupture

Hypertrophic obstructive cardiomyopathy

Hyperkinetic with low ventricular compliance

Usually elevated

Conditions affecting the valve leaflets

Marfan's syndrome

Usually intact—these conditions also affect connective tissue of chordae tendineae

Ehlers-Danlos syndrome

Osteogenesis imperfecta

Rheumatic fever

Rheumatoid arthritis

Heart block

Dilated cardiomyopathy

Other associated valve abnormalities

Ankylosing spondylitis

Atrioventricular dissociation

Aortic regurgitation

Amyloidosis

Sinoatrial and atrioventricular nodal infiltration

Restrictive and dilated cardiomyopathy

Coronary artery disease

Gout

Urate deposits in conduction system

Usually normal

Coronary artery disease

B. Tricuspid Regurgitation

Annular dilatation

Right ventricular failure

Often secondary to pulmonary hypertension

Pulmonic insufficiency

Right ventricle in failure or extremely dilated

Often secondary to pulmonary hypertension

Leaflets, chordae, and papillary muscles

Ebstein's anomaly

Acute bacterial endocarditis

Rheumatic fever

Compensation intact

Compensatory mechanisms in mitral regurgitation include ventricular dilation, elevations in ventricular filling pressure, and the maintenance of low peripheral resistance. As in aortic insufficiency, ventricular dilation allows maximum advantage to be gained from the Frank-Starling mechanism. A low peripheral resistance maintains forward flow, whereas increases in peripheral resistance increase the degree of regurgitant flow through the mitral valve. In mitral regurgitation, the heart benefits from a relatively rapid heart rate, because a slow rate is associated with an increased ventricular diastolic diameter that may distort the mitral valve apparatus even further and result in increased regurgitation, in addition to increasing oxygen demand by an increase in wall tension.

A number of diseases can be cited that interfere with the compensatory mechanisms in mitral regurgitation. When mitral regurgitation is secondary to amyloid infiltration of the mitral valve, ventricular dilatation is compromised by coincident amyloid infiltration of the ventricular myocardium, which restricts ventricular diastolic filling.^[172] Amyloid infiltration of the conduction system can cause heart block and bradycardia, resulting in increased mitral regurgitation for reasons noted earlier. In mitral regurgitation associated with left ventricular failure, there is, in addition to poor left ventricular function, an elevation of endogenous catecholamine activity, which increases peripheral vascular resistance to forward flow and regurgitant flow.

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

Tricuspid Insufficiency (see Table 2-13D )

Tricuspid insufficiency is mechanically similar to mitral insufficiency. The most common cause of tricuspid insufficiency is right ventricular failure.^[173] Even in this setting, tricuspid insufficiency is usually well tolerated, just as it is well tolerated when it exists in isolation. Tricuspid insufficiency represents a volume overload of both the right ventricle and the right atrium. But because of the high compliance of the systemic venous system, pressure in the right atrium is usually not so elevated as it is in the left atrium in mitral insufficiency. This remains true until the right ventricle loses its compliance, as it might when faced with a high afterload, as in pulmonary hypertension states.

The main compensatory mechanism in tricuspid insufficiency is adequate filling of the right ventricle. Because the right ventricle is constructed to efficiently handle a volume load, cardiac output is usually maintained. An increase in venous return, that occurs as a result of the negative intrapleural pressure resulting from spontaneous ventilation, helps maintain adequate right ventricular filling even in the presence of tricuspid insufficiency. The main reason tricuspid insufficiency is well tolerated is that it is usually superimposed on a normal right ventricle. Tricuspid insufficiency usually becomes hemodynamically significant when there is coexisting right ventricular failure. In this situation, the loss of integrity of the right ventricular chamber due to the incompetent tricuspid valve results in an increase in regurgitant flow at the expense of forward flow through the pulmonary circulation, decreasing the volume delivered to the left ventricle, with a resulting decrease in cardiac output.

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

Mitral Valve Prolapse

Mitral valve prolapse is not an uncommon disease per se, with an incidence between 5% and 20% in the general population.^[174] However, it does occur in association with uncommon diseases such as HOCM, left atrial myxoma, Wolff-Parkinson-White syndrome, long QT syndrome, Marfan's syndrome, and Ehlers-Danlos syndrome. In mitral valve prolapse, one or both mitral leaflet(s) is(are) displaced into the left atrium during ventricular systole. Complications of mitral valve prolapse include bacterial endocarditis, mitral regurgitation, thromboembolism, arrhythmias (both atrial and ventricular), syncope, and sudden death. The American Heart Association published recommendations for the prevention of bacterial endocarditis in patients with mitral valve prolapse.^[175] Patients with suspected mitral valve prolapse and concurrent murmurs of mitral regurgitation should receive endocarditis prophylaxis. Preferably, patients with suspected mitral valve prolapse should undergo echocardiographic evaluation of the mitral valve before any procedure that has an associated risk of bacteremia. Mitral regurgitation documented by Doppler echocardiography, thickening of the mitral valve leaflets or mitral valve apparatus with mitral regurgitation, or exercise-induced mitral regurgitation in patients with mitral valve prolapse is an indication for antibiotic prophylaxis of infectious endocarditis.

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

Anesthetic Considerations

Perioperative problems will arise from valvular lesions when compensatory mechanisms acutely fail. Monitoring should be selected to give a continuing assessment of the status of these compensatory mechanisms. Certain aspects of monitoring should be considered common to all valvular lesions. The electrocardiogram is essential for monitoring cardiac rhythm and ischemic changes. Filling pressures should certainly be monitored, employing either the pulmonary artery catheter or a central venous pressure catheter, as appropriate to the specific lesion. Blood pressure can best be monitored with an indwelling arterial catheter. In addition, an arterial catheter provides for the monitoring of blood gases, which are important when pulmonary function is compromised. Pulse oximetry is valuable for determining that oxygenation is adequate. TEE is useful for assessing the changes in preload and contractility that result from anesthetic and surgical manipulations. Pulsed-wave Doppler and color flow mapping are useful for determining the flow characteristics of valvular lesions and their response to pharmacologic or surgical manipulations.^[176]

In lesions such as aortic or pulmonic stenosis, where high pressure chambers have developed, monitoring of the appropriate ECG lead is mandatory for assessing ischemia.^{[179] [180]} Monitoring of rate and rhythm is especially important.^{[181] [182]} The reason for aggressive monitoring of filling pressures is clear if it is recalled that lesions, such as mitral stenosis, are exquisitely sensitive to preload.

In tricuspid and pulmonic stenosis, a pulmonary artery catheter may be difficult, if not impossible, to position. However, right-sided filling pressures indicate loading conditions in these lesions and can be monitored with a central venous pressure catheter. If the chest is to be opened in patients in whom it was not possible to pass a pulmonary artery catheter, a pulmonary artery pressure catheter can be inserted under direct vision. A left-sided atrial pressure catheter may also be inserted to follow left-sided filling pressures.

In left-sided valvular lesions, a pulmonary artery catheter is used in many institutions for monitoring both filling pressures and cardiac output. With the pulmonary artery catheter in place, vascular resistances for both the pulmonary and the systemic circulations can be calculated, allowing an assessment of therapeutic interventions, as has been mentioned before. Furthermore, changes in waveforms of the pulmonary capillary wedge pressure or central venous pressure tracings can often indicate increases in regurgitation or the development of regurgitation in situations of ventricular overdistention.

The anesthetic management of valvular lesions must avoid significant depression of contractility, because virtually all valvular lesions depend on good contractility as a major compensatory mechanism. This is especially true if the lesion coexists with a cardiomyopathy in which minor decreases in contractility can result in severe cardiac decompensation. In valvular lesions, a high-dose opioid technique probably represents the least trespass on physiologic reserves. Fentanyl, sufentanil, and remifentanil produce few cardiovascular changes, although bradycardia and chest wall rigidity may occur and postoperative ventilation is often required.^{[183] [184]} Rigidity is easily handled by the use of a neuromuscular blocker. Opioid-associated bradycardia may be advantageous in mitral and tricuspid stenotic lesions.

Nitrous oxide is a traditional supplement to narcotic analgesia, but it is a myocardial depressant and has the property of slightly increasing both pulmonary vascular resistance and SVR. This is usually not of great significance, but it may be important in severe regurgitant lesions, when it may increase regurgitant flow.^{[185] [186]} Ketamine is probably not an unreasonable anesthetic in regurgitant lesions, owing to its slight sympathetic stimulating properties, but it is contraindicated in stenotic lesions because of the problems associated with tachycardia. Etomidate is an intravenous anesthetic that is well tolerated by patients with valvular lesions.^[185] Thiopental and propofol must be administered slowly and titrated to effect if they are to be used safely in patients with valvular disease.^[186]

Neuromuscular blockers, when used in valvular lesions, should probably be selected according to their autonomic properties. For example, pancuronium may be useful in aortic or mitral insufficiency owing to the increase in heart rate. In stenotic lesions on the other hand, cisatracurium, rocuronium, and vecuronium will not result in detrimental increases in heart rate.^{[189] [190]}

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

UNCOMMON CAUSES OF ARRHYTHMIAS

Idiopathic Long QT Syndrome

This rare syndrome is usually a familial disorder. The typical patient has a primary prolongation of the QT interval (QTc > 440 ms) and syncopal episodes associated with physical or emotional stress. Congenital deafness is an associated condition.^{[191] [192]} In untreated patients, the mortality approaches 5% per year, which is quite remarkable for a population with a median age in the 20s. The severity of the disease is judged by the frequency of syncopal attacks. These attacks may be due to ventricular arrhythmias or sinus node dysfunction. The development of torsades de pointes is especially ominous and may be the terminal event for these patients.^[191] Torsades de pointes is a malignant variety of ventricular tachycardia with a rotating QRS axis that is resistant to cardioversion.^[192]

The pathogenesis of this syndrome is theorized to be an imbalance of sympathetic innervation. Left stellate ganglion stimulation lowers the threshold for ventricular arrhythmias, whereas right stellate ganglion stimulation is protective against ventricular arrhythmias. Relief of syncope and diminished mortality have been demonstrated in patients receiving β-blockers and those who have had high left thoracic sympathectomies.^[193]

Anesthetic Considerations

Whereas the occasional patient will present for high left thoracic sympathectomy and left stellate ganglionectomy, these patients will also present for surgery unrelated to their primary disorder. Because physical stress has been documented as a trigger for syncopal episodes, it would be prudent to maintain β-blockade throughout the perioperative period.

The patient's usual oral dose of β-adrenergic blocker should be given with premedication to allay anxiety. The anesthetic technique should be tailored to minimize sympathetic stimulation. A high-dose opioid anesthetic is appropriate for this purpose and is effective at suppressing catecholamine elevations in response to noxious stimuli. Nitrous oxide causes mild sympathetic stimulation and should be avoided for this reason. Isoflurane and sevoflurane prolong the QT interval, whereas halothane shortens the QT interval.^[194] Propofol has been shown to reduce the prolonged QT interval and QT dispersion in patients with idiopathic prolonged QT interval.^[195] In especially long procedures, supplemental intravenous doses of a β-blocker or a continuous infusion of esmolol should be used. Droperidol is associated with QT prolongation and should be avoided.

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

Wolff-Parkinson-White and Lown-Ganong-Levine Syndromes

Wolff-Parkinson-White (WPW) and Lown-Ganong-Levine are preexcitation syndromes that result in supraventricular tachycardias. The presence of accessory anatomic bypass tracts enables the atrial impulse to activate the bundle of His in a shorter interval than it would through the normal AV nodal pathway. If there is an increase in the refractoriness of one of the pathways, then a reentrant tachycardia can be initiated. The electrocardiogram in WPW demonstrates a short PR interval (< 0.12 second), a delta wave (slurring of the R wave upstroke), and a widened QRS complex.^[196]

Medications that produce more refractoriness in one pathway than in the other can create a window of functional unidirectional block. This initiates a circle of electrical impulse that results in a rapid ventricular rate. These patients are usually treated with drugs that prolong the refractory period of the AV node, such as β-blockers, verapamil, and digoxin, or drugs that increase the refractory period of the accessory pathway, such as procainamide and amiodarone.^[197] However, the response of an individual patient will vary depending on the window of unidirectional block and the different effects the same drug will have on both pathways. For example, verapamil and digoxin may perpetuate the arrhythmias, especially when WPW is associated with atrial fibrillation.^[198] A nonpharmacologic approach in the treatment of patients with preexcitation syndromes is catheter ablation of the accessory pathways.^{[201] [202]}

Anesthetic Considerations

The current treatment of choice for WPW is ablation of the accessory pathway, which is usually performed in electrophysiologic laboratories.^{[203] [204]} Anesthesiologists may be involved in an electrophysiologic diagnostic procedure (for young or uncooperative patients) or surgical ablative procedure.

The procedures often involve periods of programmed electrical stimulation in attempts to provoke the arrhythmias before and after the ablation of the accessory pathway. Antiarrhythmic medications are usually discontinued before the procedure. Thus, the patient presents for an anesthetic in a relatively unprotected state. Premedication is indicated to prevent anxiety that could increase catecholamine levels and precipitate arrhythmias. ECG monitoring should be optimal for the diagnosis of atrial arrhythmias (leads II and V1). In patients undergoing general anesthesia, an esophageal ECG electrode provides the best “noninvasive” atrial complex.

If tachyarrhythmias occur in the setting of an antegrade accessory pathway conduction such as WPW, drugs that prolong conduction time and refractoriness in the AV node should be avoided. Consequently, adenosine, β-blockers, calcium channel blockers, and digoxin are relatively contraindicated in the acute management of tachyarrhythmias in these patients. In the hemodynamically unstable patient, electrical cardioversion is the treatment of choice. If pharmacological treatment is necessary, amiodarone, flecainide, propafenone, or sotalol are the preferred agents; however, effects of these drugs are long lasting and may interfere with procedures and as ablation of the accessory pathways.

If general anesthesia is needed, an opioid-benzodiazepine–based or an opioid-propofol–based anesthetic regimen showed no effect on electrophysiologic parameters of the accessory conduction pathways.^[203] Volatile anesthetics increased refractoriness within the accessory and atrioventricular pathways, with halothane having the least effect, followed by isoflurane and enflurane.^[204] For patients presenting for ablation of accessory pathways, volatile anesthetics should, therefore, be avoided. For patients with preexcitation syndromes presenting for other procedures, volatile anesthetics may actually be indicated to prevent perioperative tachyarrhythmias.

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

THE TRANSPLANTED HEART

For the appropriate candidate with end-stage heart disease, heart transplantation has become a widely acceptable treatment modality, both for improving length and quality of life. The first human heart transplantation was performed in the late 1960s, but this practice was discontinued shortly thereafter because of organ rejection and opportunistic infections. Since 1980, with the introduction of more effective immunosuppression and improved survival, the procedure has emerged as a widely acceptable treatment modality for end-stage heart disease.^[205] These recipients of heart transplants may present for noncardiac surgery and, therefore, the physiology of the denervated heart and the side effects of the immunosuppressive agents must be considered.

The Denervated Heart

The recipient atrium (which may remain after transplantation) maintains its innervation; however this has no effect on the transplanted heart. Therefore, the transplanted heart is commonly referred to as being denervated. The efferent (to the heart) and afferent (away from the heart) limbs of both the parasympathetic and sympathetic nervous systems are disrupted during cardiac transplantation. This has significant impact on the physiology of the transplanted heart and the response to commonly used pharmacologic agents in the perioperative period. Some degree of sympathetic reinnervation of the transplanted heart has been documented, although this reinnervation is delayed and incomplete.^{[208] [209]}

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

Immunosuppressive Therapy

The main agents used for chronic immunosuppression are calcineurin inhibitors, azathioprine, rapamycins (everolimus/sirolimus), tacrolimus, mycophenolate mofetil, corticosteroids, and azathioprine.^{[210] [211]} These drugs may interact with anesthetic agents, and they have side effects with anesthetic implications. Cyclosporine is nephrotoxic and hepatotoxic. Another important side effect associated with the use of cyclosporine is hypertension. Cyclosporine can also lower the seizure threshold. Tacrolimus is nephrotoxic and can lead to diabetes and high blood pressure. Chronic corticosteroid therapy is associated with glucose intolerance and osteoporosis, and azathioprine is toxic to the bone marrow.

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

Anesthetic Considerations

The physiology and response to pharmacologic agents are very different in the denervated heart. The vagal innervation of the heart is disrupted, and there is a lack of heart rate variability with respiration, vagal maneuvers, and exercise. Cholinesterase inhibitors, such as neostigmine and edrophonium, do not usually produce bradycardia, although there are case reports that link cardiac arrest and bradycardia to neostigmine administration even in the transplanted heart.^{[212] [213]} However, the effects on other organ systems (e.g., salivary glands) remain intact, and these drugs must still be used in combination with anticholinergic agents.^[212] Similarly, anticholinergic agents, such as atropine, do not increase the heart rate, so that bradycardia is treated with direct-acting agents, such as isoproterenol, or with pacing. A paradoxical response with the development of AV block or sinus arrest after the administration of atropine in patients with transplanted hearts has been reported.^[213] Drugs with vagolytic side effects, such as pancuronium, do not produce tachycardia. The denervated sinus and AV nodes have been shown to be supersensitive to adenosine and theophylline.^[214]

Sympathetic stimulation can originate from two sources: neuronal or humoral. In the denervated heart, the neuronal input is initially disrupted and only partially restored, but increases in circulating catecholamines will increase heart rate. The Frank-Starling mechanism also aids in preserving the cardiac response to exercise or stress. Because of the denervation, indirect-acting cardiovascular agents have unpredictable effects. The response of the coronary circulation may also be affected.^{[217] [218]}

The normal innervated heart responds to an increase in aerobic demand mainly by an increase in heart rate. However, the initial response of the denervated heart to an increased demand is via the Frank-Starling mechanism: increasing stroke volume through preload augmentation. The increase in heart rate via the humoral pathway or circulating catecholamines is delayed. Overall, the response of the denervated heart to exercise or increased metabolic demand is subnormal.^{[219] [220] [221]}

Sensory fibers in the heart play an important role in maintaining SVR. With rapid changes in SVR, the denervated heart may not respond appropriately, and these patients tolerate hypovolemia poorly. Sensory fibers in the heart are also important in the manifestations of myocardial ischemia. As such, the patient with a denervated heart may not experience angina, although there are reports to the contrary.

Another factor that must be considered in the anesthetic management of these patients is that the transplanted heart is also predisposed to accelerated coronary artery disease. Fibrous proliferation of the intima of epicardial vessels may result from a chronic rejection process and, within 5 years of transplantation, many patients would have developed significant occlusion of their coronary arteries.^{[222] [223]}Therefore, these patients must be evaluated for coronary artery disease.

The immunosuppressive agents also should be considered in the anesthetic plan. Cyclosporine is nephrotoxic and hepatotoxic and, therefore, these organ systems must be evaluated. Corticosteroids predispose patients to osteoporosis and gentle positioning is required. Patients on azathioprine should have an appropriate hematologic workup in the preoperative period.^{[224] [225]}

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

AIDS AND THE HEART

In 2002, there were nearly 900,000 cases of AIDS in the United States according to the Centers for Disease Control and Prevention.^[224] The current estimates indicate that more than 40 million people worldwide may be infected with HIV.^[225] HIV affects all organ systems, including the cardiovascular system. The heart can be affected by the HIV virus directly, and by opportunistic infections related to the immunocompromised state, malignancies common to the disease, and drug therapy.

Left ventricular diastolic function is affected early in the course of HIV infection. Coudray and colleagues^[226] performed an echocardiographic evaluation on 51 HIV-positive patients and compared the results with data obtained from age- and sex-matched controls and found that HIV-positive patients, regardless of the presence of symptomatic disease, had impaired left ventricular diastolic function. The mechanism of this dysfunction is unclear but may be secondary to viral myocarditis, and the clinical significance remains to be determined. In contrast to this diastolic dysfunction early in the course of the infection, systolic dysfunction has been reported late in the course of the disease. This systolic dysfunction may be caused by zidovudine.^[227]

Zidovudine is an antiviral agent that inhibits HIV reverse transcriptase. Electron microscopic studies have demonstrated that zidovudine disrupts the mitochondrial apparatus of cardiac muscle.^{[230] [231]}Domanski and coworkers, in a randomized prospective study, found that children infected with HIV who were treated with zidovudine had a significant decrease in left ventricular ejection fraction when compared with children infected with HIV who had not received zidovudine.^[230] They suggested that left ventricular function should be evaluated by serial examination. Starc and coworkers found that 18% to 39% of children who were diagnosed with AIDS developed cardiac dysfunction within 5 years of follow-up and that cardiac dysfunction was associated with an increased risk of death.^[231] The effects of the newer antiviral agents on the heart have not yet been established.

Heart involvement was found in 45% of patients with AIDS in an autopsy study.^[232] Pericardial effusion, dilated cardiomyopathy, aortic root dilation and regurgitation, and valvular vegetations were the more frequent findings.^{[235] [236]} The pericardium is sometimes affected by opportunistic infections such as cytomegalovirus and by tumors, such as Kaposi's sarcoma and non-Hodgkin's type lymphoma. In addition, an autonomic neuropathy associated with HIV infection has been shown to cause QT prolongation, which may predispose these patients to ventricular arrhythmias.^[235]

Anesthetic Considerations

Early in the course of HIV infection there is diastolic dysfunction that is usually clinically insignificant. As the disease progresses, and with prolonged treatment with zidovudine, there is reduction in left ventricular systolic function.^[236] Signs and symptoms of left ventricular failure may be masked by concurrent pulmonary disease. An echocardiographic evaluation may provide useful information in this setting. Patients with advanced disease may also have pericardial involvement with pericardial effusion and tamponade.

General anesthesia is considered safe, but drug interactions and their impact on various organ systems and the patients overall physical status should be considered preoperatively. General anesthesia suppresses the immune system, but adverse effects on the disease progress in patients diagnosed with HIV infection or AIDS could not be documented.^[237] Regional anesthesia is often the technique of choice, and early concerns about neuraxial anesthesia and the potential spread of infectious material intrathecally could not be confirmed.^{[240] [241] [242] [243] [244]}

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

CONCLUSION

Although the main focus of each of these sections has been on the cardiovascular pathology encountered in uncommon diseases, the clinician should remember that very few of these diseases have isolated cardiovascular pathology. Many of the diseases discussed are severe multisystem diseases, and an anesthetic plan must also consider the needs of monitoring dictated by other systemic pathology (e.g., measurements of blood sugar in diabetes secondary to hemochromatosis) and the potential untoward effects of drugs in unusual metabolic disturbances (e.g., the use of drugs with histamine-releasing properties such as thiopental or morphine in the malignant carcinoid syndrome).

Certainly, it cannot be proven or stated that one anesthetic technique is absolutely superior to all others in the management of any particular lesion, particularly those due to the unusual conditions discussed here. The key to the proper anesthetic management of any uncommon disease lies in an understanding of the disease process, particularly the compensatory mechanisms involved in maintaining cardiovascular homeostasis, the cardiovascular effects of anesthetic drugs, and the appropriate monitoring of the effects of anesthetic and therapeutic interventions.

Fleisher: Anesthesia and Uncommon Diseases, 5th ed.

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