Pericardial and Myocardial Disease

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Chapter 82

Pericardial and Myocardial Disease

Pericardial Disease (Pericarditis)

Perspective

Our knowledge of pericardial function and disease has increased greatly since Hippocrates described the pericardium in 460 BC as “a smooth tunic that envelops the heart and contains a small amount of fluid resembling urine.” Galen provided the first description of a pericardial effusion and performed the first pericardial resection.1 Lancisi first described the appearance of constrictive pericarditis at autopsy in 1728. Also in the 18th century, Laennec said, “There are few diseases attended by more variable symptoms and more difficult to diagnose than [pericarditis].”1 In 1935, Beck described the clinical presentation of cardiac tamponade, known as Becks triad (hypotension, jugular venous distention, and muffled heart sounds).2 Despite the passage of time and the modern availability of many diagnostic tools, the diagnosis and treatment of pericardial disease still present a challenge.

Etiology

Each of the disorders listed in Box 82-1 can produce acute pericarditis, with or without pericardial effusion. In addition, most of these disorders can progress to cardiac tamponade or constrictive pericarditis.

Most cases of pericarditis in developed countries are idiopathic. Even exhaustive clinical testing identifies a specific cause in less than 20% of patients, with the remainder being idiopathic despite often being putatively of viral cause.

Principles of Disease

Pericardial Anatomy and Physiology

The normal pericardium envelops the heart and attaches to the great vessels. It consists of parietal and visceral layers, with a narrow potential space between them. The visceral layer or epicardium adheres to the myocardium. It is separated from the parietal layer by a potential space. Each layer is 1 or 2 mm thick and is composed of elastic fibers. The position of the heart within the chest is stabilized by the attachment of the parietal pericardium to the sternum, the diaphragm, and the vertebral column. Its blood supply comes from the internal mammary artery, and its nerve supply from the phrenic nerve.3

An ultrafiltrate of plasma, 15 to 35 mL of fluid, is normally contained in the pericardial space. Abnormal amounts of pericardial fluid can accumulate when the venous or lymphatic drainage of the heart is obstructed. The pericardium serves several functions: it maintains the heart’s position, lubricates the heart’s surface, prevents the spread of infection, prevents cardiac overdilation, augments atrial filling, and maintains the normal pressure-volume relationships of the cardiac chambers. Patients with congenital absence (or surgical removal) of the pericardium, however, show few, if any, problems.

Idiopathic Pericarditis

Clinical Features

The classic symptoms of pericarditis include chest pain, pericardial friction rub, and electrocardiogram (ECG) abnormalities. A history of fever and myalgia is common. Pericarditis chest pain usually is sharp and pleuritic and varies with position. It is typically relieved by sitting forward and is worsened by lying down, deep inspiration, or swallowing. Pericarditis pain is usually retrosternal, can radiate to the trapezius muscles, and may manifest as isolated shoulder pain. Pain can also be felt in the area of the diaphragm.

The physical examination hallmark of acute pericarditis is the pericardial friction rub. The rub may be caused by friction between inflamed or scarred visceral and parietal pericardium or may result from friction between the parietal pericardium and adjacent pleura. It may be audible anywhere over the anterior chest wall but usually is best heard at the lower left sternal border. Friction rubs are best heard via the diaphragm of the stethoscope, with the patient leaning forward in full expiration. The rub also can be accentuated by a full inspiration, followed by a breath hold, during which auscultation is performed. The rub tends to be intermittent, migratory, and difficult to hear in a loud ED.

Diagnostic Strategies

There is no single test that is diagnostic for pericarditis. The ECG is the most reliable diagnostic tool. It evolves through stages that occur over time. The first stage occurs in the first hours to days of illness. It includes diffuse ST segment elevation seen in leads I, II, III, aVL, aVF, and V2 through V6 and also reciprocal ST segment depression in aVR and V1. Most patients with acute pericarditis have concurrent PR segment depression (Fig. 82-1). In the next stages, the ST and PR segments normalize, but the T waves flatten, and then there is deep, symmetrical T wave inversion. At the last stage, the ECG reverts to normal, although the T wave inversions may become permanent.4

The early ECG findings of acute pericarditis may be difficult to distinguish from acute myocardial infarction (MI), coronary artery spasm, or benign early repolarization. The differentiation of acute MI from acute pericarditis is essential. Thrombolytic therapy is contraindicated in pericarditis because its use may precipitate hemorrhagic cardiac tamponade. In contrast to the ECG in acute MI, the ST segment elevations in stage 1 acute pericarditis are concave rather than convex upward, and simultaneous T wave inversions are not seen. Subsequent tracings do not evolve through a typical MI pattern, and Q waves do not appear.

Differentiation of pericarditis from ST elevation MI is often difficult, especially if the history is atypical or the patient has a significant communication barrier, such as language. When the ECG pattern suggests ACS and the pain is not clearly pericarditic in nature, often the best course is early diagnostic coronary angiography.

Ventricular dysrhythmias are rare in pericardial disease. Patients with pericarditis who have ventricular dysrhythmias should be presumed to have concomitant myocarditis or another cardiac disease or to have been misdiagnosed.

Echocardiography facilitates the definitive diagnosis of pericarditis with effusion, although it will be normal in patients without significant effusion, and a normal echocardiogram cannot be used to exclude pericarditis. In addition, cardiac tamponade, increased pericardial thickness, pericardial tumors and cysts, constrictive pericarditis, and the congenital absence of the pericardium can all be diagnosed by echocardiography.

Some patients with acute pericarditis have elevated cardiac markers caused by myopericarditis, myocarditis, or MI. The white blood cell count and erythrocyte sedimentation rate (ESR) may be elevated or normal and are not sensitive or specific. Other laboratory studies should be directed at determining nonidiopathic causes of pericarditis.

Management and Disposition

If a specific cause of pericarditis is found, therapy should be specific for that cause. Otherwise, therapy for acute pericarditis is symptomatic. Anti-inflammatory therapy will reduce pain, and a nonsteroidal anti-inflammatory drug (NSAID) is the treatment of first choice. Ibuprofen has the best side effect profile, but other NSAIDs should be equally effective. The patient will often report significant pain relief from the analgesic effect of the ibuprofen while in the ED, even before onset of the anti-inflammatory effect. A dose of 600 mg four times a day for 1 week is a good initial therapy. If the chosen NSAID is not effective within 1 week, a different class of NSAIDs should be tried, such as indomethacin 25 mg three times a day for 1 week. Colchicine (1.2 initially then 0.6 mg daily for up to 6 months) is effective for recurrent pericarditis, and steroid therapy (1 mg/kg daily) has shown mixed results.5,6

Uremic Pericardial Disease

Clinical Features and Diagnostic Strategies

Patients with uremic pericarditis have chest pain, unexplained fever, and possibly a coarse friction rub. They also may have significant effusions. The ECG in uremic pericarditis is often normal because little epicardial inflammation occurs.7 In a dialysis patient, cardiac enlargement on chest radiograph in the absence of signs of volume overload or congestive heart failure (CHF) should prompt consideration of pericardial effusion. An echocardiogram will provide the definitive answer. Pericardiocentesis may be needed to exclude infection.

Post–Myocardial Infarction Pericarditis

Approximately 20% of patients with transmural MIs experience a different quality of chest pain 2 to 4 days after infarction. This pain may represent early post-MI pericarditis. There is frequently low-grade fever and a transient pericardial friction rub. A large pericardial effusion is unusual. Early post-MI pericarditis is generally short-lived and disappears with 1 to 3 days with aspirin therapy (325 mg/day).

The ECG changes of pericarditis usually are masked by the acute MI changes. Patients with early post-MI pericarditis have more dysrhythmias and heart failure. Pericarditis in acute MI may be an indicator of greater myocardial damage and a worse outcome.

Dressler reported a syndrome of fever, pleuritis, leukocytosis, pericardial friction rub, and chest radiograph evidence of new pericardial or pleural effusions in post-MI patients.8 Frequent relapses and a high incidence of friction rubs led Dressler to describe this syndrome as a delayed complication of MI in contrast to the well-known syndrome of early post-MI pericarditis. The cause of late post-MI pericarditis (Dressler’s syndrome) may be immunologic, but the syndrome may also occur with pulmonary embolus and after pericardiotomy. Anticoagulants should be discontinued to reduce the risk of hemorrhage. Delayed post-MI pericarditis is treated with NSAIDs such as ibuprofen 600 mg four times per day or indomethacin 25 mg three times per day.

Postinjury Pericarditis

Principles of Disease

Injury to the pericardium in blunt trauma may range from contusion to laceration or rupture. Some degree of traumatic pericarditis is found during surgery or at autopsy in many patients sustaining severe blunt trauma of the chest.

Penetrating wounds to the heart usually cause laceration of the pericardium and the myocardium, with secondary pericarditis and pericardial infections. Although the exact incidence is unknown, infection, tamponade, myocarditis, and inflammatory pericarditis may occur.

An immune pathogenesis is suggested by the development of cardiac autoantibodies, although these autoantibodies are common after injury, even in patients who do not develop pericarditis. Constrictive pericarditis occurs secondary to trauma. This may be caused by pericardial blood, possibly secondary to the decreased resorptive power of damaged pericardium, with secondary fibrosis and constriction.

Neoplastic Pericardial Disease

Pericardial Disease Related to Connective Tissue Disorders

Pericarditis occurs in approximately one third of patients with rheumatoid arthritis (RA), usually within 3 years of the initial diagnosis. Rheumatoid pericardial disease is rarely clinically significant. Occasional patients develop effusions, constrictive pericarditis, or cardiac tamponade. These patients usually have rheumatoid nodules, elevated circulating rheumatoid factor levels, and valvular heart disease. Pericardial fluid may have rheumatoid factor or a low glucose level. Corticosteroid treatment is useful. Prednisone 1 mg/kg/day is the initial treatment, with close follow-up appointment.

Pericarditis is found at autopsy in more than 50% of patients with systemic lupus erythematosus (SLE). The effusion is usually thick and fibrinous. Either cardiac tamponade or constrictive pericarditis may develop. Lupus erythematosus cells may be identified in pericardial fluid specimens. Corticosteroid therapy is indicated.

Other connective tissue diseases that may cause pericarditis include Sjögren’s syndrome, giant cell arteritis, ankylosing spondylitis, Reiter’s syndrome, Behçet’s disease, systemic sclerosis, and polyarteritis nodosa.

Pericardial Effusion

Diagnostic Strategies

Pericardial effusion may cause an enlarged cardiac silhouette on chest radiograph, usually with normal pulmonary vasculature. A minimum of 200 to 250 mL of pericardial fluid is necessary to produce cardiomegaly on a chest radiograph.

Echocardiography is the diagnostic modality of choice (Fig. 82-2). It easily differentiates pericardial fluid from cardiac chamber enlargement and provides information about myocardial wall motion.

CT may be useful in diagnosing pericardial effusion when the echocardiogram is technically unsatisfactory. MRI can also be diagnostic. Nuclear scans may be useful in detecting purulent pericardial effusions.

Pericardiocentesis may be performed for either diagnostic or therapeutic purposes. Elective diagnostic pericardiocentesis is indicated in cancer patients (to differentiate malignant effusion from postradiation pericarditis), for failure to respond to usual treatment, or when bacterial infection is suspected. Common complications of pericardiocentesis include induction of cardiac dysrhythmias, pneumothorax, perforation of myocardium, laceration of coronary or internal mammary arteries, and liver laceration. Echocardiographic-guided pericardiocentesis is the procedure of choice.

Pericardial fluid should be analyzed for protein, glucose, specific gravity, cell count and differential, Gram’s stain, and culture. Other tests, depending on the clinical picture, include cytology, acid-fast stain, fungal smear, and connective tissue disease screening.

The gross appearance of the pericardial fluid provides a clue to the cause. Serosanguineous effusions are associated most commonly with neoplasms, tuberculosis, uremia, radiation, and idiopathic pericarditis. Grossly bloody effusions are caused by blunt or penetrating trauma, postinfarction myocardial rupture, aortic dissection, coagulopathies, and iatrogenic cardiac perforation. Purulent pericardial fluid is seen with pneumonia, empyema, and sepsis.

Cardiac Tamponade

Etiology and Pathophysiology

Ten percent of all patients with cancer develop cardiac tamponade.10 Cardiac tamponade should be suspected in patients with penetrating chest wounds. It is also common in patients with uremic pericarditis.

Cardiac tamponade is the result of compression of the myocardium by the contents of the pericardium. This compression is usually caused by fluid, but it may be caused by gas, pus, blood, or a combination of factors.

Cardiac tamponade is a physiologic continuum reflecting the amount of fluid, the rate of accumulation, and the nature of the heart. The three stages necessary for tamponade to develop are fluid filling the recesses of the parietal pericardium, fluid accumulating faster than the rate of the parietal pericardium’s ability to stretch, and accumulation that exceeds the body’s ability to increase blood volume to support right ventricle filling pressure. The final result is increased pericardial pressure, which causes decreased ventricle compliance and decreased flow of blood into the heart. The reduction of blood inflow into the right ventricle results in decreased stroke volume that leads to decreased cardiac output.10 The most important factor in the development of tamponade is the rate of fluid accumulation.

The heart initially responds to tamponade by increasing heart rate to maintain cardiac output. This compensatory mechanism is maintained until late in the clinical course, followed by decompensation.

Diagnostic Strategies

The chest radiograph shows cardiomegaly only if there is a large accumulation of fluid (250 mL). The ECG classically shows decreased voltage or electrical alternans (Fig. 82-3), but the latter is rare. Echocardiography confirms the diagnosis when an effusion and paradoxical systolic wall motion are seen. Thermodilution catheters can also be diagnostic, showing equalization of right and left ventricular pressures.

Purulent Pericarditis

Tuberculous Pericarditis

Tuberculous pericarditis is estimated to occur in 1 or 2% of patients with pulmonary tuberculosis.12 In Africa, it is the most common cause of pericarditis. In countries in which tuberculosis is not a major health problem, tuberculous pericarditis is most common in patients who are socioeconomically deprived or immunodeficient. In many patients the chest radiograph shows an enlarged cardiac silhouette without a pulmonary infiltrate. Pericardial fluid aspirates reveal acid-fast bacilli by smear or culture (which may require 4-6 weeks to become positive) in approximately 50% of cases. Diagnostic workup should include assessment for human immunodeficiency virus (HIV). Patients with tuberculous pericarditis should be hospitalized and observed for evidence of cardiac tamponade. Triple-drug therapy should be started in the hospital and continued for at least 9 months. Patients with chronic pericardial effusions may benefit from oral prednisone therapy. The mortality rate is approximately 15% in HIV-negative patients and 20 to 35% in HIV-positive patients.12

Other Causes of Pericarditis

Amyloid deposition can cause either restrictive cardiomyopathy (RCM) or constrictive pericarditis. Pericarditis can occur rarely as an extraintestinal complication of inflammatory bowel disease and is independent of the clinical course of the gut disorder.

Iatrogenic pericarditis can also occur as a complication of an implantable defibrillator or an atrial lead of a permanent pacemaker. A polymicrobial bacterial pericarditis can occur after transbronchial needle aspiration or as a complication of endoscopic variceal sclerotherapy. Rarely, pericarditis can also be caused by erosion of a foreign body, such as a sewing needle or toothpick, through the esophagus into the pericardium.

Less than 1% of patients with HIV develop acute pericarditis, but 40% have asymptomatic pericardial effusion. Pericardial effusion is more frequent in patients in the more advanced stages of HIV infection. The clinical features and diagnostic evaluation of patients with HIV-related pericarditis are the same as those in patients without acquired immunodeficiency syndrome (AIDS).

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