Constrictive pericarditis refers to a condition where the heart is encased by a thickened, fibrotic, or calcified pericardium, leading to restricted ventricular diastolic filling and a series of circulatory disturbances. The disease is typically chronic in nature.
Etiology
Constrictive pericarditis can result from a variety of pericardial diseases. The most common cause is tuberculous pericarditis, followed by idiopathic pericarditis, purulent pericarditis, or traumatic pericarditis. In recent years, cases caused by radiation-induced pericarditis and post-cardiac surgery have been increasing. Other causes include malignancies, connective tissue diseases, uremia, and certain medications.
Pathophysiology
During early ventricular diastole, blood flows rapidly into the ventricles. However, in mid-to-late diastole, ventricular expansion becomes abruptly restricted by the pericardium, impeding further filling. This results in a rapid rise in intraventricular pressure, reduced stroke volume, and compensatory tachycardia to maintain cardiac output. Impaired systemic venous return can lead to symptoms such as jugular venous distension, hepatomegaly, ascites, and lower extremity edema. During inspiration, increased venous return to the heart is not accommodated due to the constricted pericardium, causing further elevation in venous pressure and more pronounced jugular venous distension, a phenomenon known as Kussmaul's sign.
Clinical Manifestations
Symptoms
Patients often have a history of pericarditis, pericardial effusion, malignancy, chest radiation therapy, or thoracic and cardiac surgery. Some patients present with insidious onset and no obvious symptoms in the early stages. The primary symptoms are related to reduced cardiac output and systemic venous congestion, including palpitations, exertional dyspnea, decreased exercise tolerance, fatigue, hepatomegaly, ascites, pleural effusion, and lower extremity edema.
Signs
Elevated jugular venous pressure is common. Pulse pressure is often narrowed, and pulsus paradoxus is uncommon. Cardiac apex beat may be weakened or absent, and most patients exhibit negative systolic apex pulsation. The cardiac dullness area is either normal or slightly enlarged. Heart sounds are weak and distant, typically without murmurs. In some cases, a pericardial knock can be heard at the left sternal border in the 3rd-4th intercostal space, occurring after the second heart sound as a sharp, knocking sound caused by the sudden deceleration of blood flow into the diastolically restricted ventricles. Heart rate is usually elevated and may be sinus rhythm, atrial or ventricular arrhythmias, or premature contractions. Kussmaul's sign is often positive.
Auxiliary Examinations
X-ray
X-ray imaging often shows a mildly enlarged cardiac silhouette with a triangular or globular shape, straightened left and right cardiac borders, a small or indistinct aortic arch, and enlarged superior vena cava. In some cases, the cardiac silhouette appears normal, but pericardial calcification may be present.
Electrocardiography (ECG)
Common ECG findings include tachycardia, low-voltage QRS complexes, and flattened or inverted T waves. Some patients may exhibit widened, notched P waves. In long-standing cases or elderly patients, atrial fibrillation may be observed.
Echocardiography
M-mode, two-dimensional, and Doppler echocardiography are the most commonly used non-invasive diagnostic tools. Typical findings include pericardial thickening, adhesion, cardiac deformation, reduced ventricular wall motion, and paradoxical motion of the interventricular septum during diastole (septal bounce). Hepatic and inferior vena cava dilation may also be observed. Echocardiography can assess the presence of pericardial effusion and detect fibrous encasement. Respiratory variation in the E wave of the mitral and tricuspid Doppler flow spectra is a helpful diagnostic feature.
Cardiac CT and Magnetic Resonance Imaging (MRI)
Cardiac CT and MRI are more effective than echocardiography in diagnosing chronic constrictive pericarditis. Both modalities can evaluate the extent and severity of pericardial involvement, pericardial thickness, and calcification. CT is more sensitive in detecting pericardial calcification, while MRI is better at identifying small pericardial effusions, adhesions, and inflammation.
Right Heart Catheterization
When non-invasive methods are inconclusive or before planned pericardiectomy, right heart catheterization can be performed. Characteristic findings include elevated and equalized pressures in the pulmonary capillary wedge, pulmonary artery diastolic, right ventricular end-diastolic, right atrial, and central venous pressures. The right atrial pressure waveform typically shows an M- or W-shaped pattern. Right ventricular pressure may show mild elevation with a characteristic early diastolic dip and plateau ("square root" sign). Discordant changes in left and right ventricular pressure curves during respiration are also observed.
Tissue Biopsy
Pericardioscopy and pericardial biopsy can help determine the underlying cause.
Diagnosis and Differential Diagnosis
The diagnosis of constrictive pericarditis is often based on typical clinical manifestations and auxiliary examinations. Differentiation from restrictive cardiomyopathy is essential. Heart failure is often associated with significantly enlarged cardiac borders, bilateral pulmonary crackles, elevated serum BNP levels, and findings of cardiac enlargement and pulmonary congestion on chest X-ray. Echocardiography, cardiac CT, and MRI are helpful in confirming the diagnosis. When ascites is the predominant presentation, differentiation from conditions such as cirrhosis and tuberculous peritonitis should be considered.
Prognosis
Early and complete surgical pericardiectomy can lead to satisfactory outcomes in some patients. However, a poor prognosis is associated with prolonged disease duration, significant myocardial atrophy, or severe complications such as cardiogenic liver cirrhosis.
Treatment
Most patients progress to chronic constrictive pericarditis, where pericardiectomy is the only effective treatment, though the perioperative risk is high. In rare cases, pericardial constriction may be transient or reversible. For patients with recent diagnoses and stable conditions, anti-inflammatory treatment for 2-3 months may be attempted unless complications such as cardiac cachexia, cardiogenic liver cirrhosis, or myocardial atrophy are present. Antitubercular therapy is recommended for tuberculous pericarditis to slow disease progression, with postoperative antitubercular treatment continuing for one year.
Prevention
Prevention primarily involves the prompt treatment of underlying diseases, such as standardized antitubercular therapy for tuberculous pericarditis, aggressive anti-infective treatment for purulent pericarditis, and early surgical drainage when necessary. Enhancing immunity and reducing the risk of infections are also important.