Bo Burns
Ninety percent of valvular disease is chronic, with decades between the onset of the structural abnormality and onset of symptoms.
Through chronic adaptation by dilation and hypertrophy cardiac function can be preserved for years, which may delay the diagnosis for one to two decades until a murmur is detected on auscultation.
The four heart valves prevent retrograde flow of blood during the cardiac cycle, allowing efficient ejection of blood with each contraction of the ventricles. The mitral valve has two cusps, while the other three heart valves normally have three cusps. The right and left papillary muscles promote effective closure of the tricuspid and mitral valves, respectively.
Compared to the general population, patients with hemodynamically significant valvular heart disease have a 2.5-fold increased rate of death and a 3.2-fold increased rate of stroke.
MITRAL STENOSIS
EPIDEMIOLOGY
Despite its declining frequency, rheumatic heart disease is still the most common cause of mitral valve stenosis.
Women are twice as likely as men to have mitral stenosis.
PATHOPHYSIOLOGY
The majority of patients eventually develop atrial fibrillation because of progressive dilation of the atria.
Although the valvular obstruction is slowly progressive, symptoms tend to appear acutely, when obstruction becomes sufficient to prevent compensatory increase in cardiac output (eg, during exercise).
CLINICAL FEATURES
As with all valvular diseases, the most common presenting symptom is exertional dyspnea (seen in 80% of patients with mitral stenosis).
Hemoptysis, historically the second most common presenting symptom, has become less common due to earlier recognition and treatment of valvular disease.
Systemic emboli may result in myocardial, renal, central nervous system, or peripheral infarction.
The classic murmur and signs of mitral stenosis are listed in Table 25-1.
TABLE 25-1 Comparison of heart Murmurs, Sounds, and Signs
DIAGNOSIS AND DIFFERENTIAL
The electrocardiogram (ECG) may demonstrate notched or biphasic P waves and right axis deviation (see Figure 25–1).
On the chest radiograph, straightening of the left heart border, indicating left atrial enlargement, is a typical early radiographic finding. Eventually, there are findings of pulmonary congestion: redistribution of flow to the upper lung fields, Kerley B lines, and an increase in vascular markings.
FIG. 25-1. An ECG demonstrating left atrial enlargement and right axis deviation in a patient with mitral stenosis. Note abnormal P waves in lead V2. (Courtesy of David Cline, Wake Forest University).
The diagnosis of mitral stenosis should be confirmed with echocardiography and/or cardiology consultation. Symptom severity determines the urgency of ascertaining an accurate diagnosis and arranging for appropriate referral.
EMERGENCY DEPARTMENT CARE AND DISPOSITION
The medical management of mitral stenosis includes intermittent diuretics, such as furosemide 40 milligrams IV, to alleviate pulmonary congestion; treatment of atrial fibrillation (see Chapter 4); and anticoagulation for patients at risk for arterial embolie events.
Patients with mitral stenosis and paroxysmal or chronic atrial fibrillation or a history of an embolic event should be on long-term anticoagulation. The goal of warfarin therapy is an international normalized ratio (INR) goal of 2 to 3.2.
Frank hemoptysis may occur in the setting of mitral stenosis and pulmonary hypertension.
Bleeding may be sufficiently severe to require blood transfusion, consultation with a thoracic surgeon, and emergency surgery.
MITRAL INCOMPETENCE
EPIDEMIOLOGY
Infective endocarditis or myocardial infarction can cause acute rupture of the chordae tendineae or papillary muscles or cause perforation of the valve leaflets.
Inferior myocardial infarction due to right coronary occlusion is the most common cause of ischemic mitral valve incompetence.
Although an association between aortic regurgitation and appetite suppressant drugs (fenfluramine and phentermine, or dexfenfluramine alone) has generally been accepted the suspected association of mitral incompetence with appetite suppressants remains unclear.
PATHOPHYSIOLOGY
Acute regurgitation into a noncompliant left atrium quickly elevates pressures and causes pulmonary edema. In contrast, in the chronic state the left atrium dilates so that left atrial pressure increases little, even with a large regurgitant flow
CLINICAL FEATURES
Acute mitral incompetence presents with dyspnea, tachycardia, and pulmonary edema. Patients may quickly deteriorate to cardiogenic shock or cardiac arrest.
Intermittent mitral incompetence usually presents with acute episodes of respiratory distress due to pulmonary edema, and can be asymptomatic between attacks.
Chronic mitral incompetence may be tolerated for years or even decades. The first symptom is usually exertional dyspnea, sometimes prompted by atrial fibrillation. Systemic emboli (often asymptomatic) occur in 20% of patients who are not anticoagulated.
The classic murmur and signs of mitral incompetence are listed in Table 25-1.
DIAGNOSIS AND DIFFERENTIAL
In acute rupture, the ECG may show evidence of acute inferior wall infarction (more common than anterior wall infarction in this setting).
On the chest radiograph, acute mitral incompetence from papillary muscle rupture may be manifest by a minimally enlarged left atrium and pulmonary edema, with less cardiac enlargement than expected.
In chronic disease, the ECG may demonstrate findings of left atrial and left ventricular hypertrophy (LVH). On chest radiography, chronic mitral incompetence produces left ventricular and atrial enlargement proportional to the degree of regurgitant volume.
Echocardiography is essential to make the diagnosis with certainty and determine severity (see Fig. 25-2). Bedside technique may be mandatory in the acutely ill patient. However, transthoracic echocardiography may underestimate lesion severity, and transesophageal imaging should be undertaken as soon as the patient is adequately stable. In stable patients, echocardiography can be scheduled electively.
FIG. 25-2. An echocardiogram demonstrating severe mitral regurgitation. Color flow Doppler shows regurgitant flow back into left atrium. (Courtesy of S. Mahler)
EMERGENCY DEPARTMENT CARE AND DISPOSITION
Pulmonary edema should be treated initially with oxygen, non-invasive positive pressure ventilation, diuretics, as-tolerated nitrates, and intubation for failing respiratory effort.
Nitroprusside increases forward output by increasing aortic flow and partially restoring mitral valve competence as left ventricular size diminishes. Consider nitroprusside at 5 micrograms/kg/min IV unless the patient is hypotensive.
There may be a subset of patients in whom mitral regurgitation is worsened by nitroprusside (those patients who respond with dilation of the regurgitant orifice), so careful monitoring is essential.
Hypotensive patients should receive inotropic agents such as dobutamine 2.5 to 20 micrograms/kg/min in addition to nitroprusside.
Aortic balloon counterpulsation increases forward flow and mean arterial pressure while diminishing regurgitant volume and left ventricular filling pressure; this intervention can be used to stabilize a patient while awaiting surgery.
Emergency surgery should be considered in cases of acute mitral valve rupture.
MITRAL VALVE PROLAPSE
EPIDEMIOLOGY
Mitral valve prolapse is the most common valvular heart disease in industrialized countries, affecting about 2.4% of the population.
Population studies comparing patients with mitral valve prolapse to those without the disorder have found no increased risk of atrial fibrillation, syncope, stroke, or sudden death.
PATHOPHYSIOLOGY
The etiology of mitral valve prolapse, or the click-murmur syndrome, is unknown but the condition may be congenital.
Male sex, age over 45, and the presence of regurgitation (recognized clinically by a short systolic murmur), are associated with higher risk for complications.
CLINICAL FEATURES
Most patients are asymptomatic. Symptoms include atypical chest pain, palpitations, and fatigue and dyspnea unrelated to exertion.
The abnormal heart sounds are listed in Table 25-1.
In patients with mitral valve prolapse without mitral regurgitation at rest, exercise-induced mitral regurgitation (which occurs in 32% of cases) predicts a higher risk for morbid events.
DIAGNOSIS AND DIFFERENTIAL
Echocardiography is recommended to confirm the clinical diagnosis of mitral valve prolapse and to identify any associated mitral regurgitation. Echocardiography and/or consultation with a cardiologist can be performed on an outpatient basis.
EMERGENCY DEPARTMENT CARE AND DISPOSITION
Initiating treatment for mitral valve prolapse is rarely required for patients seen in the ED. Patients with palpitations, chest pain, or anxiety frequently respond to β-blockers, such as atenolol 25 milligrams qd. Avoiding alcohol, tobacco, and caffeine may also relieve symptoms.
AORTIC STENOSIS
EPIDEMIOLOGY
Degenerative heart disease (or calcific aortic stenosis) is the most common cause of aortic stenosis in adults residing in the United States.
Congenital heart disease is the most common cause of aortic stenosis in young adults, with the presence of a bicuspid valve accounting for 50% of cases. Rheumatic heart disease, the third most common cause in the United States, remains the most common cause worldwide.
PATHOPHYSIOLOGY
Blood flow into the aorta is obstructed, producing progressive LVH and low cardiac output.
CLINICAL FEATURES
The classic triad is dyspnea, chest pain, and syncope.
Dyspnea is usually the first symptom, followed by paroxysmal nocturnal dyspnea, syncope on exertion, angina, and myocardial infarction.
The classic murmur and associated signs of aortic stenosis are listed in Table 25-1.
Blood pressure is normal or low, with a narrow pulse pressure.
Brachioradial delay is an important finding in aortic stenosis. The examiner simultaneously palpates the right brachial artery of the patient with the thumb and the right radial artery of the patient with the middle or index finger. Any palpable pulse delay between the brachial artery and radial artery is considered abnormal.
DIAGNOSIS AND DIFFERENTIAL
The ECG usually demonstrates criteria for LVH and, in 10% of patients, left or right bundle-branch block.
The chest radiograph is normal early, but patients who do not receive valve replacement eventually manifest LVH and findings of congestive heart failure.
Echocardiography should be undertaken to confirm the suspected diagnosis of aortic stenosis in the hospital if the murmur is associated with syncope (see Fig. 25-3).
FIG. 25-3. Parasternal long-axis plane demonstrating a thickened, stenotic aortic valve. Ao = aorta; LA = left atrium; LV = left ventricle. (Reproduced with permission from Fuster V, O’Rourke RA, Walsh RA, Poole-Wilson P. eds. Hurst’s The Heart, 12th edition. New York: McGraw-Hill. 2008.)
EMERGENCY DEPARTMENT CARE AND DISPOSITION
Patients presenting with pulmonary edema can be treated with oxygen and diuretics, but nitrates should be used with caution since preload reduction may cause significant hypotension. Nitroprusside is not well tolerated in patients with aortic stenosis.
New-onset atrial fibrillation may severely compromise cardiac output, and therefore require anticoagulation with heparin and cardioversion.
Patients with profound aortic stenosis-related symptoms (eg, syncope) should be admitted to the hospital.
AORTIC INCOMPETENCE
EPIDEMIOLOGY
In 20% of patients, the cause of aortic incompetence is acute in nature. Infective endocarditis accounts for the majority of acute cases; the remainder are cased by dissection at the aortic root. Calcific degeneration, congenital disease (most notably bicuspid valves), systemic hypertension, myxomatous proliferation, and rheumatic heart disease cause the majority of chronic cases.
Marfan syndrome, syphilis, ankylosing spondylitis, Ehlers-Danlos syndrome, and Reiter syndrome are less frequent causes.
An association between the appetite suppressant drugs (fenfluramine and phentermine or dexfenfluramine alone) has been found for aortic incompetence.
PATHOPHYSIOLOGY
In acute cases, a sudden increase in backflow of blood into the ventricle raises left ventricular end-diastolic pressure, which may cause acute heart failure.
In chronic disease, the ventricle progressively dilates to accommodate the regurgitant blood volume. Wide pulse pressures result from the fall in diastolic pressure, and marked peripheral vasodilatation is seen.
CLINICAL FEATURES
In acute disease, the most common presenting symptom is dyspnea, seen in 50% of patients. Many patients have acute pulmonary edema with pink frothy sputum. Patients may complain of fever and chills if endocarditis is the cause.
Dissection of the ascending aorta typically produces a “tearing” chest pain that may radiate between the shoulder blades.
The classic murmur and signs of aortic incompetence are listed in Table 25-1.
In the chronic state, about one-third of patients will have palpitations associated with a large stroke volume and/or premature ventricular contractions. Frequently these sensations are noticed in bed.
In the chronic state, signs include a wide pulse pressure with a prominent ventricular impulse, which may be manifested as head bobbing.
“Water hammer pulse” may be noted; this is a peripheral pulse that has a quick rise in upstroke followed by a peripheral collapse.
Other classic findings may include accentuated precordial apical thrust, pulsus bisferiens, Duroziez sign (a to-and-fro femoral murmur), and Quincke pulse (capillary pulsations visible at the proximal nail bed, while pressure is applied at the tip).
DIAGNOSIS AND DIFFERENTIAL
ECG changes may be seen with aortic dissection, including ischemia or findings of acute inferior myocardial infarction, suggesting involvement of the right coronary artery.
In patients with acute regurgitation, the chest radiograph demonstrates acute pulmonary edema with less cardiac enlargement than expected.
In chronic aortic incompetence, the ECG demonstrates LVH, and the chest radiograph shows LVH, aortic dilation, and possibly evidence of congestive heart failure.
Echocardiography is essential for confirming the presence and evaluating the severity of valvular regurgitation. Bedside transthoracic echocardiography should be undertaken in the unstable patient potentially in need of emergency surgery. Transesophageal echocardiography is recommended when aortic dissection is suspected, but this approach may not be feasible in acutely unstable patients.
EMERGENCY DEPARTMENT CARE AND DISPOSITION
Pulmonary edema should be treated initially with oxygen and intubation for failing respiratory effort. Diuretics and nitrates can be used, but are often ineffective.
Nitroprusside (start at 5 micrograms/kg/min) along with inotropic agents such as dobutamine (start at 2.5 micrograms/kg/min) or dopamine can be used to augment forward flow and reduce left ventricular end-diastolic pressure in an attempt to stabilize a patient prior to emergency surgery.
Intra-aortic balloon counterpulsation is contraindicated.
Although β-blockers are often used in treating aortic dissection, these drugs should be used with great caution, if at all, in the setting of acute aortic valve rupture because they will block the compensatory tachycardia.
Emergency surgery may be life-saving.
Chronic aortic regurgitation is typically treated with vasodilators such as angiotensin-converting enzyme (ACE) inhibitors or nifedipine (initiated by a patient’s longitudinal care physician).
PROSTHETIC VALVE DISEASE
EPIDEMIOLOGY
Prosthetic valves are implanted in 40,000 patients per year in the United States. There are approximately 80 types of artificial valves, each with advantages and disadvantages. Patients who receive prosthetic valves are instructed to carry a descriptive card in their wallet.
Patients with artificial valves develop endocarditis at a rate of 0.5% per year. Infections occur more frequently during the first 2 months after operation. The most common organisms during this period are Staphylococcus epidermidis and S. aureus. Gram-negative organisms and fungi are also frequent causes of endocarditis during this early period.
The most important complications of mechanical heart valves, bleeding, and systemic embolism originating from a thrombus on the prosthetic valve, occur at rates of 1.4% and 1% per year, respectively, for patients on warfarin.
PATHOPHYSIOLOGY
Prosthetic valves tend to be slightly stenotic, and a very small amount of regurgitation is common because of incomplete closure.
Patients with mechanical valves require continuous anticoagulation. Some bioprostheses do not require long-term anticoagulation, unless atrial fibrillation is coexistent.
Thrombi can form on a prosthetic valve and may become large enough to obstruct flow or prevent closure. The dysfunction due to thrombi can be acute or slowly progressive.
Bioprostheses may gradually degenerate, undergoing gradual thinning, stiffening, and possible tearing, which result in valvular incompetence.
The sutures that secure the prosthetic valve may become disrupted, leading to perivalvular regurgitation as a fistula forms at the periphery of the valve.
Mechanical models may suddenly fracture or fail. These failures usually bring sudden symptoms and often cause death before corrective surgery can be accomplished.
CLINICAL FEATURES
Many patients have persistent dyspnea and reduced effort tolerance after successful valve replacement. This is more common in the presence of pre-existing heart dysfunction or atrial fibrillation.
Large paravalvular leaks usually present with congestive heart failure. Patients with new neurologic symptoms may have thromboembolism associated with the valve thrombi or endocarditis.
Patients with prosthetic valves usually have abnormal cardiac sounds. Mechanical valves have loud, metallic closing sounds.
Systolic murmurs are commonly present with mechanical models. Loud diastolic murmurs are generally not present with mechanical valves.
Patients with bioprostheses usually have normal S1 and S2, with no abnormal opening sounds.
The aortic bioprostheses are usually associated with a short midsystolic murmur.
DIAGNOSIS AND DIFFERENTIAL
New or progressive dyspnea of any form, new onset or worsening of congestive heart failure, decreased exercise tolerance, or a change in chest pain compatible with ischemia all suggest valvular dysfunction.
Persistent fever in patients with prosthetic valves should be evaluated for possible endocarditis with blood cultures.
Blood studies that may be helpful include a blood count with red blood cell indices and coagulation studies if the patient is on warfarin.
Emergency echocardiographic studies should be requested if there is any question about valve dysfunction. Ultimately, echocardiography and/or cardiac catheterization may be required for diagnosis.
EMERGENCY DEPARTMENT CARE AND DISPOSITION
It is critical that patients suspected of having acute prosthetic valvular dysfunction have immediate referral to a cardiac surgeon for possible emergency surgery.
The intensity of anticoagulation therapy varies with each type of mechanical valve, but ranges from an INRgoalof2to3.5.
Acute prosthetic valvular dysfunction due to throm-botic obstruction has been successfully treated with thrombolytic therapy, but the diagnosis generally requires consultation with a cardiologist. Lesser degrees of obstruction should be treated with optimization of anticoagulation.
Disposition of patients with worsening symptoms can be problematic, and consultation with the patient’s longitudinal care physician may be needed prior to consideration for discharge.
PROPHYLAXIS FOR INFECTIVE ENDOCARDITIS
See Chapter 95 for recommendations on prophylaxis prior to procedures performed in the emergency department.
For further reading in Emergency Medicine: A Comprehensive Study Guide, 7th edition., see Chapter 58, “Valvular Emergencies” by Simon A. Mahler.