Constrictive Pericarditis

Etiology

Worldwide, tuberculosis is the leading cause of constrictive pericarditis, and the incidence is about 50% among patients with tuberculous pericardial effusion despite antitubercular therapy. In developed nations, the leading cause of this condition is idiopathic or postviral infection, accounting for 40% to 60% of total cases. Constrictive pericarditis is also a known complication of cardiac surgical procedures and is a fairly common complication of mediastinal radiation therapy, with an incidence ranging from 2% to 30% in patients treated with radiation. Constrictive pericarditis has also been associated with connective tissue disorders such as rheumatoid arthritis and systemic lupus erythematosus. Diagnosis of constrictive pericarditis may be fairly simple; however, establishing the underlying cause is often difficult. In many cases, a cause cannot be identified and is attributed to an asymptomatic episode of viral pericarditis.[4][5][6] 

Epidemiology

Approximately 9% of patients with acute pericarditis develop constrictive physiology. In the resource-limited world, infectious etiologies such as tuberculosis remain the most common cause. The condition is rare in adults and even rarer in children; it is more common in patients who have undergone cardiac surgery. A 3:1 predominance in men with no known racial predilection has been reported.[7][8][9]

Pathophysiology

The pathophysiology of chronic constrictive pericarditis involves obliteration of the pericardial cavity by granulation tissue during the healing of an acute episode of fibrinous or serofibrinous pericarditis or during the resorption of chronic pericardial effusion. Over time, the granulation tissue gradually contracts, encasing the heart and potentially becoming calcified, resulting in a rigid, thickened pericardium that limits ventricular filling because the elastic limit of the diseased pericardium is much lower than that of a normal pericardium. Ventricular filling during early diastole is not affected and is only impeded when the elastic limit of the pericardium is reached, in contrast to cardiac tamponade, in which ventricular filling is impeded throughout diastole. This process results in decreased end-diastolic volume and, consequently, decreased stroke volume and cardiac output. The thickened and scarred pericardium prevents the normal inspiratory decrease in intrathoracic pressure from being transmitted to the heart chambers.

As a result, dissociation between intrathoracic and intracardiac pressures occurs. This dissociation leads to decreased venous return with inspiration because pulmonary venous pressure decreases. However, left atrial pressure does not, and pulmonary venous flow into the left atrium decreases during inspiration. This dissociation of intrathoracic and intracardiac pressures is a distinguishing feature from cardiac tamponade, because in cardiac tamponade, changes in intrathoracic pressure are transmitted to the heart, and systemic venous return increases with inspiration. In both disorders, the right atrial, right ventricular, left ventricular, and pulmonary wedge diastolic pressures are equalized; however, in cardiac tamponade, the pressure decreases with inspiration, whereas in constrictive pericarditis, the right atrial pressure remains constant while the pulmonary wedge pressure decreases.[10][11][12]

History and Physical

Patients often present with chronic symptoms. These symptoms may be related to volume overload, such as weight gain and swelling, or to decreased cardiac output, including progressive fatigue and dyspnea on exertion. Patients may also report an increase in abdominal girth or abdominal discomfort. These abdominal findings are secondary to either ascites or congestive hepatomegaly.

On physical examination, jugular venous pressure is typically elevated; however, it may be normal in early constrictive pericarditis. Jugular venous pressure does not decrease during inspiration, a finding known as the Kussmaul sign. Kussmaul sign is also present in tricuspid valve disease and right-sided heart failure.

Pulsus paradoxus, a drop in systolic blood pressure of more than 10 mm Hg during inspiration, can be observed; however, the Kussmaul sign is more common in patients with cardiac tamponade. An accentuated heart sound heard earlier than the third heart sound, called a pericardial knock, is present in almost half of patients. Abdominal examination may reveal ascites or hepatomegaly. Other signs of chronic illness, such as muscle wasting, may be present depending on the etiology. Peripheral edema may also be present.

Evaluation

Echocardiography

The American College of Cardiology and the European Society of Cardiology guidelines recommend echocardiography for diagnosing constrictive pericarditis and other pericardial diseases. Two-dimensional echocardiography may show increased pericardial thickness, with or without calcification. This technique may also reveal dilation of the inferior vena cava without inspiratory collapse.

A sharp halt in diastolic filling may be seen along with the abrupt transient movement of the intraventricular septum towards the right side, which is also known as septal bounce.[2][4][13] M-mode echocardiography is crucial for ruling out constrictive pericarditis. The following features are frequently observed in constrictive pericarditis, and the absence of these features on M-mode makes the diagnosis very unlikely:

• Posterior motion of the ventricular septum during early diastole with inspiration 
• Absence of an increase in systemic venous return with inspiration 
• Premature opening of the pulmonic valve due to higher right ventricular diastolic pressure compared to pulmonary arterial pressure

Doppler echocardiography is used to evaluate the hemodynamics of the disease and may reveal the following:

• Abnormal passive filling of the ventricles in early diastole 
• Increase in diastolic flow velocity across the tricuspid valve during inspiration and a decrease during expiration 
• Exaggerated reduction in flow velocity in the pulmonary veins and across the mitral valve in inspiration, and a leftward shift of the ventricular septum 
• Hepatic vein Doppler may show reduced hepatic vein diastolic forward flow and reversal of hepatic vein flow at end diastole [14]

Cardiac Magnetic Resonance Imaging

Cardiac magnetic resonance imaging (MRI) has advanced significantly over the past 2 decades and is now frequently used to evaluate the pericardium and myocardium. Echocardiography remains the standard imaging technique for diagnosing constrictive pericarditis. However, cardiac MRI can provide confirmatory information or help rule out the diagnosis. MRI features suggestive of constrictive pericarditis include pericardial thickening, pericardial calcification, myopericardial tethering, diastolic restraint, and dilation of the inferior vena cava.[15]

Electrocardiogram 

No specific electrocardiographic findings of constrictive pericarditis are present, although the test may reveal nonspecific ST-segment changes and low voltage. Advanced and long-standing cases may show atrial fibrillation secondary to elevated atrial pressures. Computed tomography and cardiac MRI are also frequently performed, especially before surgical procedures for constrictive pericarditis.

These imaging studies can reveal a thickened pericardium and calcifications. Computed tomography scans can detect calcifications more effectively than cardiac MRI. Cardiac MRI is better at differentiating small effusions from pericardial thickening. Myocardial fibrosis or atrophy observed on computed tomography or MRI is associated with a poor surgical outcome. Occasionally, patients undergo right heart catheterization for hemodynamic studies, which may reveal increased right atrial pressure, increased right ventricular end-diastolic pressure, prominent x- and y-descents on venous and atrial pressure tracings, and a greater inspiratory fall in pulmonary capillary wedge pressure than in left ventricular diastolic pressure.

Treatment / Management

Pericardiectomy is the only definitive treatment for chronic constrictive pericarditis, and surgeons should attempt to remove as much of the pericardium as possible. Extensive penetration of the myocardium by fibrosis and calcification is associated with poor outcomes. Perioperative mortality ranges from 10% to 55% and has decreased over time. Clinicians should consider the procedure very cautiously in patients with mild disease with few symptoms or in patients with advanced disease and other comorbidities because of the high mortality associated with the procedure. Diuretics can be used to reduce edema or elevated venous pressures before the surgical procedure or for palliative control of symptoms in patients who are not surgical candidates.[1][16][17][18]

A subset of patients may have spontaneous resolution or may respond to medical treatment, and they are said to have transient constrictive pericarditis. Patients with newly diagnosed constrictive pericarditis who are hemodynamically stable and do not have the stigmata of chronic constriction may be treated with anti-inflammatory agents for up to 3 months under close monitoring. If these patients develop signs of chronic constriction and hemodynamic instability, they should undergo prompt surgical procedures.

Differential Diagnosis

The differential diagnosis for constrictive pericarditis includes:

• Cardiac sarcoma
• Cardiac tamponade
• Dilated cardiomyopathy
• Hemochromatosis
• Pericardial effusion
• Sarcoidosis
• Tricuspid regurgitation

Prognosis

In the United States, constrictive pericarditis is uncommon, and long-term data are scarce. Anecdotal reports suggest that when the diagnosis is made early, the outcomes are good. However, if the disorder is misdiagnosed or untreated, mortality rates in excess of 90% are common. For patients who undergo pericardiectomy, the 10-year survival is about 50%. Medical therapy alone is associated with a poor life expectancy. Long-term survival after constrictive pericarditis depends on the underlying cause.

The worst outcomes are observed in patients with radiation-induced constrictive pericarditis, and the best outcomes are observed in patients following open heart surgery. Negative prognostic factors include advanced age, renal dysfunction, low ejection fraction, and elevated pulmonary artery pressures. Most patients who are untreated quickly develop multiorgan dysfunction, hypoxia, and metabolic acidosis. Patients should be promptly referred to a tertiary care center that specializes in the treatment of constrictive pericarditis when treatment is not available at the presenting hospital.[19][20][21]

Complications

The complications that can manifest with constrictive pericarditis are as follows:

• Pulmonary hypertension
• Hepatomegaly
• Shock
• Renal failure
• Metabolic acidosis
• Hypoxemia
• Death