Rudolph's Pediatrics, 22nd Ed.

CHAPTER 491. Pericardial Diseases

Julien I. E. Hoffman

The pericardium is a 2-layered sac that contains the heart and the proximal parts of the great vessels. The outer surface of the sac is termed the parietal pericardium and is lined by mesothelial cells. The inferior part of the sac is attached to the diaphragm. The inner layer of the sac, also lined by mesothelial cells, is attached to the cardiac surface and is known as the visceral pericardium. A small amount of fluid fills the cavity between the pericardial layers and acts as a lubricant so that the heart can move within the sac. The parietal pericardium has blood and lymphatic vessels. Disorders that affect the pericardium may be primary or secondary to disease elsewhere in the body, including the heart itself.

Whatever the cause, there are only 3 manifestations: acute or chronic inflammation of the pericardial sac in response to injury or accumulation of fluid between the 2 layers—a pericardial effusion with or without a tamponade.

ACUTE PERICARDITIS

Acute pericarditis has many causes (see Table 491-1). No matter what the cause, the presentation is similar.

1. Chest pain is usually precordial and often referred to the neck, shoulder, or epigastrium. The pain is sharp or burning and is usually made better by sitting up and leaning forward. It is made worse by taking in a deep breath because inspiration lowers the diaphragm, pulls the pericardial sac down, and narrows it, thereby causing the 2 pericardial layers to rub together more forcefully.

2. A pericardial friction rub is heard. A grating sound occurs when the 2 layers rub together. This rub has the sound of sandpaper on wood, but occasionally resembles creaking leather. The friction rub has a to-and-fro rhythm (or sometimes 3 components) and is heard in systole and diastole. It may become louder with firm pressure and is heard best along the left sternal border, with the patient sitting up and leaning forward. The rub, however, may be intermittent. The auscultator should not confuse a friction rub with the sounds made when the stethoscope is moved over skin or chest hairs.

Table 491-1 Etiology^a of Pericarditis

^aThe most commone causes are printed in bold type.

3. Fever is common and has no special characteristics. As a rule, it is higher when there is an acute bacterial infection (staphylococcus, pneumococcus, haemophilus) than a viral infection.

4. The electrocardiogram initially shows elevation of the ST segments in the leads facing the pericardium (I, II, aVF, V₃ to V₆) because the inflammation of the visceral pericardium extends deeper to the superficial myocardium and produces a current of injury that changes the ST segment. Leads that do not face the epicardium (aVR and V₁) show reciprocal ST depression. These diffuse ST changes help to separate acute pericarditis from acute myocardial infarction in which the current of injury is localized to a few leads. After 5 to 7 days, the ST segments return to the baseline and then become inverted in the leads that originally showed elevation. Unlike the changes of myocardial ischemia, these inverted T waves are symmetrical. With recovery the electrocardiogram usually returns to normal, but in some patients may remain abnormal for years.

5. Chest x-ray is unremarkable in the absence of an effusion.

Treatment of acute pericarditis depends on its cause and is discussed below.

PERICARDIAL EFFUSION

An increase in the amount of pericardial fluid is termed a pericardial effusion. The fluid may be serous, purulent, or bloody, and it moves the pericardial layers apart from each other.

1. An effusion per se produces no symptoms apart from those associated with its cause, thus an effusion is often unsuspected.

2. Because of the increased amount of fluid, the heart sounds are muffled and a previously heard pericardial friction rub may disappear. On the other hand, in some patients the heart may float on top of the fluid and bring out a friction rub not previously heard. A sign of a moderate or large effusion is an increased region of cardiac dullness on percussion, with the left edge of the dullness clearly beyond the position of the apex beat. This is one of the few times when cardiac percussion is useful.

3. Because the increased amount of pericardial fluid (if more than minimal) increases the intrapericardial volume, the chest x-ray may show an enlarged cardiac silhouette. Classically, this resembles a water flask (the kind made of flexible leather or skin) that has a narrow neck and a rounded bulging lower portion. Unfortunately, most patients with a pericardial effusion have nonspecific enlargement of the cardiac silhouette. Finding low concentrations of atrial natriuretic peptide or brain natriuretic peptide (BNP) indicates that the enlarged cardiac silhouette is not caused by cardiac dilatation.¹

4. The electrocardiogram is nonspecific, but may show unusually small voltages in all leads due to the volume effect or electrical alternans because the heart may swing within the enlarged pericardial cavity.^2-4

5. The gold standard for diagnosis is the echocardiogram that shows unequivocally the increased space between the pericardial layers (Fig. 491-1). Care is needed if smaller amounts of fluid are pooled behind the heart.

PERICARDIAL TAMPONADE

Normally, the pressure in the pericardial sac is low. When an effusion accumulates, the pressure may remain low if the increased fluid volume is small or accumulate so slowly that the parietal pericardium stretches and does not become tense. It is possible for a huge effusion to coexist with a normal intrapericardial pressure. If the effusion forms rapidly, or if the pericardium is stiff because of inflammatory changes, the intrapericardial pressure can rise and compress the heart—a pericardial tamponade. In these patients the cardiac silhouette may not be enlarged.⁵ A slowly enlarging effusion may be well tolerated for a long time, and then intrapericardial pressures may rise suddenly because the limits of pericardial distensibility have been reached. These pressure changes can occur rapidly. If the heart was previously enlarged, the events may be taken mistakenly to indicate worsening of the primary heart disease.

Compression impairs cardiac relaxation and filling. Ventricular end-diastolic and atrial pressures rise on both sides of the heart by about equal amounts, jugular venous pressure rises, the liver enlarges, and cardiac output and stroke volume fall. Heart rate increases, blood pressure and pulse pressure decrease, and there is reduced peripheral perfusion with cold, clammy extremities. Pericardial tamponade is a major cardiac emergency. Systolic function is not impaired initially, but left ventricular output is reduced because left ventricular filling is reduced. The patient has all the features of congestive heart failure and is often mistakenly diagnosed with such. Although an echocardiogram makes the definitive diagnosis of an effusion, it is often difficult to decide if there is a tamponade as well. It is best to make the diagnosis clinically by testing for Kussmaul sign and pulsus paradoxus.

Kussmaul sign is an increase in jugular venous pressure on inspiration. Normally, during inspiration the intrathoracic pressure decreases so that, despite the increased venous return, right atrial and jugular venous pressures decrease. If the compressed heart cannot accommodate the increased venous return, then the right atrial and jugular venous pressures increase. The sign is not specific because it can also occur with constructive pericarditis (see below), restrictive cardiomyopathy, and sometimes in right heart failure.

FIGURE 491-1. Apical long-axis view from a patient with cardiac tamponade. A: During early diastole, right ventricular collapse is present (arrow). B: Normal curvature of the right ventricular wall is present during systole. LA, left atrium; LV, left ventricle; PE, pericardial effusion; RV, right ventricle.

Pulsus paradoxus is the single most important diagnostic test for pericardial tamponade. Normally, if one feels the radial pulse and takes a deep breath, the pulse diminishes slightly. This occurs because taking a deep breath lowers intrathoracic pressure, causing the cardiac afterload to increase. The pressure inside the heart decreases relative to atmospheric pressure, but pressure in the peripheral arteries is unaffected by respiration so that the heart has more work to do to pump blood around the body. (If you are pumping water from a well into a pipe and you lower the water level in the well, less water will be pumped out unless the force of the pump is increased.) It takes a few beats for the heart to adjust to the increased load. In a patient with pericardial tamponade, this effect is exaggerated for several reasons, and the radial pulse becomes very faint or may even become impalpable. It was this phenomenon that led to the term pulsus paradoxus: There was no radial pulse, but the cardiac apex beat could be felt easily.

To measure pulsus paradoxus, place a blood pressure cuff normally around the arm, and with the patient breathing quietly, measure systolic pressure. Now have the patient take and hold a deep breath and quickly check the systolic pressure. In a tamponade this will be much lower than the resting pressure. In a normal person, even the deepest inspiration will not produce more than about 4 to 8 mm Hg difference between resting and inspiratory pressures, but with tamponade much greater pressure differences are produced with much less inspiratory effort. In severe tamponade, of course, noting the radial pulse disappear during inspiration makes the diagnosis of pulsus paradoxus easily. The blood pressure method, however, allows quantitation and makes it possible to follow the progress of the tamponade if immediate treatment is not performed. The difference in pressures is also noted in diastole but is easier to measure in systole.

Pulsus paradoxus may occur in the absence of a pericardial tamponade or constriction during an asthmatic attack or in chronic obstructive airway disease.⁸ Both pulsus paradoxus and Kussmaul sign are unreliable indicators of tamponade if the patient is on positive-pressure ventilation.¹²

On echocardiography, tamponade can be suspected from 2 signs: (1) During inspiration, the cross-sectional area of the right ventricle increases as it fills, but the area of the left ventricle decreases,^13,14associated with a marked decrease in diastolic flow across the mitral valve; (2) in diastole, the thin walls of the right atrium and right ventricle collapse,^15,16 and in very severe tamponade the left atrial wall may also collapse (Fig. 491-1).¹⁷

PERICARDIOCENTESIS

Because pericardial tamponade can be fatal, it should usually be treated as an emergency by removing fluid—a pericardiocentesis. Lesser degrees of tamponade may be managed conservatively, provided that the patient can be observed closely during treatment; vital signs should be taken frequently, and hemodynamic stability should be assured by blood gas and lactate measurements. If tamponade becomes worse or is severe when the patient is first seen, then fluid should be removed. An early sign of progression is increasing tachycardia, even in the absence of hypotension. If there is any sign of significant tamponade, demonstrated either by changes in the clinical findings or laboratory findings of a metabolic or lactic acidosis, pericardiocentesis should be performed on an emergency basis.

CHRONIC CONSTRICTIVE PERICARDITIS

Infrequently, the parietal and visceral layers of the pericardium are fused and thickened. Calcification may develop in the pericardium, and the underlying myocardium may be atrophic or involved in the inflammatory process.

Chronic pericarditis affects the heart by restricting its ability to dilate. As a result diastolic ventricular filling is impaired, but systolic contraction is usually unaffected. As with acute pericarditis, patients with chronic pericarditis present similarly, whatever the cause.

1. The patients present with signs and symptoms of what appears to be congestive heart failure from a restrictive cardiomyopathy. They have a raised jugular venous pressure, hepatomegaly, peripheral edema, and ascites that is often out of proportion to the peripheral edema.¹⁹ Pulmonary edema is absent or minimal.¹ There may be protein-losing enteropathy and hypoalbuminemia. The hepatomegaly and ascites may lead to the mistaken diagnosis of cirrhosis of the liver.

2. Clinically, the heart sounds may be distant. Frequently, there is a loud pericardial knock in early diastole that coincides with the abrupt cessation of filling when blood from high-pressure left and right atria rushes into the ventricles that have limited expansion because of the rigid pericardium. At this time a rapid fall in jugular venous pressure can be seen. Kussmaul sign and pulsus paradoxus occur (see above).

3. Chest x-ray is not diagnostic. It may be helpful if it shows calcification or if the cardiac silhouette appears small for the degree of congestive heart failure. Pleural effusions may be seen, but do not distinguish this entity from other causes of congestive heart failure. If the cardiac silhouette is enlarged, congestive heart failure due to underlying heart disease may be mistakenly diagnosed.

4. The electrocardiogram does not show any specific changes.

5. The diagnosis may be very difficult to make, even using sophisticated noninvasive techniques. The thickened pericardium may be seen on imaging by echocardio-gram, magnetic resonance, or computed tomography.^20-22 Some patients require cardiac catheterization, but even so, it may be difficult to differentiate the restrictive filling pattern of restrictive cardiomyopathy from the pattern of constrictive pericarditis. Myocardial or pericardial biopsy may be necessary before the diagnosis can be assured.²³

Treatment is by surgical removal of the thick pericardium. The procedure is often very difficult, and there is a risk of injuring superficial coronary arteries that are concealed by the thick fibrous tissue. The procedure is not always successful because the fibrous tissue was not completely removed, coronary arteries were damaged, or diffuse fibrosis extended into the myocardium from the surface.

SPECIFIC DISEASES

INFECTION

Rheumatic Fever

Acute rheumatic fever with extensive pancarditis is now uncommon in the United States. Pericarditis usually occurs after or with valvulitis and myocarditis, but the friction rub and effusion may mask the other features. Tamponade and constrictive pericarditis are very rare. Treatment is discussed in Chapter 235.

Acute Nonspecific Pericarditis

Acute nonspecific pericarditis, probably viral, often follows a respiratory infection. About 70% of the time the causative agent can be identified in pericardial fluid by serologic tests or polymerase chain reaction. Among the viruses found have been coxsackie, Epstein-Barr, adenovirus, cytomegalovirus, and influenza and parainfluenza viruses.²⁴ The acute phase is manifested by fever, malaise, anorexia, and pericardial pain; in infants there are also tachycardia and tachypnea. There is a polymorphonuclear leukocytosis. A pericardial friction rub and effusions are common, and typical electrocardiographic changes are seen. The patients are not usually very ill, and tamponade and constrictive pericarditis are rare. Recovery occurs spontaneously in 2 to 4 weeks. Treatment is usually symptomatic, with or without nonsteroidal anti-inflammatory agents, but steroids may be needed occasionally for recurrent or unusually severe or long-lasting disease. Recurrences occur in 15% to 32% of patients.²⁵

If there is evidence of an underlying myocarditis, as shown by echocardiography, care must be taken in using nonsteroidal anti-inflammatory agents or steroids because these may make the myocarditis worse. Recently, recurrent pericarditis and effusions have been treated successfully with colchicine, given with or without a loading dose, in doses of 0.25 to 0.5 mg/day for up to 6 months.^26,27

About 25% to 50% of children with HIV have an effusion, but tamponade is rare.

Purulent Pericarditis

Purulent pericarditis occurs after seeding from a septic focus in the lung (pneumonia or empyema), with septicemia, or, rarely, after cardiac surgery.^28-35 The common organisms are staphylococci, pneumococci, streptococci, Haemophilus influenzae, and meningococci; these organisms can usually be isolated from blood and pericardial fluid. The incidence of H influenzae infections has been declining, however, with current immunization practices. The illness has an acute onset, with a high swinging fever, marked polymorphonuclear leukocytosis, and severe toxicity.

Close observation for tamponade is essential. Constrictive pericarditis can occur very early, but in others it may follow cure so that an extended follow-up is necessary. Many patients require early pericardiectomy if the causative organism is H influenzae, if tamponade follows the initial pericardiocentesis, or if fever persists despite adequate antibiotic treatment.³⁹ Some surgeons prefer to delay a pericardiectomy for 2 to 6months to allow the inflammatory changes to heal,³⁴ but other surgeons find the procedure easier if done within the first 2 weeks. Pericardiectomy can be done thoracoscopically.⁴⁰

Tuberculous Pericarditis

Tuberculous pericarditis usually complicates tuberculosis elsewhere. It starts insidiously with malaise, anorexia, low-grade fever, and night sweats, and then the typical features of pericarditis develop; there may be an effusion.⁴¹Diagnosis is by a positive tuberculin test; isolation of tubercle bacilli from pericardial fluid, sputum, or gastric washings; and histologic examination of the pericardium. Adenosine deaminase concentrations in the pericardial fluid, normally 0 to 18 U/L, usually exceed 50 U/L.⁴² Polymerase chain reaction may help to identify the organism. Antituberculous therapy is effective. Some studies with adjunctive steroids suggest more rapid resolution of the effusion but no effect on the subsequent constrictive pericarditis⁴³ that is a common sequel. Some experts advocate early pericardiectomy to avoid having to remove dense fibrous tissue later. Other causes of chronic infectious pericarditis are various fungi as well as actinomycosis or nocardiosis.

NONINFECTIOUS CAUSES

Trauma

Hemopericardium occurs after blunt or penetrating trauma, including cardiac massage, and tamponade may occur rapidly. Thus, emergency pericardiocentesis may be needed while preparations are made for surgery. Bleeding into the pericardial cavity may occur in patients taking anticoagulants. Constrictive pericarditis is a rare sequela. Tamponade may also occur with bleeding after cardiac surgery and must be considered for any low cardiac output syndrome in the postoperative period. It may not have classical signs if the patient is on positive-pressure respiration.

Collagen Diseases

In rheumatoid arthritis, pericarditis and high fevers may precede joint involvement. Treatment should be by salicylate or colchicine, with steroids reserved for refractory lesions.^44,45 About 40% of patients with systemic lupus erythematosus may have associated pericarditis with effusions,⁴⁶ and occasionally they have cardiac tamponade that may rarely be the presenting abnormality.⁴⁷ The effusion may persist after other symptoms disappear with steroid therapy. Pericarditis and effusions are rare in dermatomyositis and polymyositis,⁴⁸ but may be more common in systemic sclerosis (scleroderma).^{49, 50}

Uremia

Pericarditis and effusions, even tamponade, may occur with acute⁵¹ or chronic uremia and are seen more often now that chronic hemodialysis is often used in these patients. Effusions may be hemorrhagic. Small pericardial effusions are very common and may disappear spontaneously.^52-58 The disorder may be difficult to diagnose because of associated cardiomegaly and heart failure in some patients. With longer survival due to hemodialysis or transplantation, constrictive pericarditis has occasionally developed.

Miscellaneous

Pericarditis and effusions may occur after radiation of the chest, with foreign bodies in or near the pericardium, with the rare tumors that occur there, and secondary to metastatic malignancy.⁵⁹ If effusions after radiation persist beyond 2 to 3 months, a pericardial window may be created surgically to permit drainage. Dissecting aneurysm, hypothyroidism, sarcoidosis, multiple myeloma, and acute pancreatitis are rare causes. Pericardial effusions are seen with fetal hydrops.

Postpericardiotomy Syndrome

Postpericardiotomy syndrome may follow any operation in which the pericardium is opened. The syndrome is uncommon in infants. Up to 30% of these patients have attacks of acute pericarditis and fever beginning about 1 to 4 weeks (range, 3 days to 6 months) after surgery. There is often a pericardial effusion and sometimes a pleural effusion that need not be on the side of the thoracotomy. Although echocardiography is the mainstay of diagnosis, an effusion per se does not make the diagnosis; after a cardiac operation with a pericardiotomy, about 50% of children have a small effusion at the time of discharge from the hospital. There is a mild polymorphonuclear leukocytosis and an increased sedimentation rate. Patients with the syndrome have high titers of a heart-reactive antibody, and 70% show an acute rise of antibodies to adenoviruses, coxsackie B, or cytomegalovirus. The current belief is that an immune response is triggered by viral invasion of traumatized myocardial tissue.^60,61 A similar syndrome may occur after myocardial infarction.

Treatment by bed rest and acetylsalicylic acid (120 mg/kg/day) or another nonsteroidal anti-inflammatory agent is usually effective. Once the acute attack is under control, the drug can be slowly withdrawn over 6 weeks; more rapid withdrawal may lead to recurrences, which may occur in 10% to 15% of patients in any event. Occasionally, steroids may be needed if there is no response to this treatment. One patient was treated successfully with high-dose immunoglobulin,⁶² and a trial of prevention by colchicine is in progress.⁶³

Congenital Lesions

Congenital pericardial lesions are rare and include absence of the pericardium which is usually harmless, pericardial defects through which chambers of the heart can herniate causing pain or even death, and congenital cysts or diverticula. Diagnosis can usually be made by echocardiography.