Pericarditis

Acute pericarditis is an inflammation of the pericardium that is most commonly caused by infection or myocardial infarction, or occurs following cardiac surgery. The condition typically presents with fever, pleuritic chest pain, and a pericardial friction rub heard on auscultation. The diagnosis is established based on clinical findings, although diffuse ST segment elevations on ECG and imaging may support the diagnosis. Acute pericarditis is usually self-limiting within 2–6 weeks and is therefore managed symptomatically. Constrictive pericarditis occurs as a complication of acute pericarditis and is characterized by thickening and rigidity of the pericardium, resulting in both backward and forward failure. Accordingly, patients present with fatigue, jugular vein distention, peripheral edema, and a characteristic pericardial knock on auscultation, caused by a sudden stop in ventricular diastolic filling. Diagnostic imaging shows typical pericardial thickening on chest x-ray and reduced blood flow on echocardiography. Management consists of treatment of heart failure (e.g., diuretics) and pericardiectomy.

• Acute pericarditis is inflammation of the pericardium that either occurs as an isolated process or with concurrent myocarditis. Conditions that primarily affect the pericardium are referred to as myopericarditis, those which predominantly affect the myocardium as perimyocarditis. However, these terms are often used interchangeably.
• Constrictive pericarditis is characterized by compromised cardiac function caused by a thickened, rigid, and fibrous pericardium secondary to acute pericarditis.

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• Infectious
  • Most commonly viral
  • Bacterial (e.g., tuberculosis, seen especially in constrictive pericarditis)
  • Fungal
  • Toxoplasmosis
• Myocardial infarction: pericarditis may occur either within 1–3 days as an immediate reaction (i.e., post-infarction fibrinous pericarditis), or weeks to months following an acute myocardial infarction (Dressler syndrome).
• Postoperative (post-pericardiotomy syndrome): blunt or sharp trauma to the pericardium
• Collagen vascular disease: systemic lupus erythematosus, rheumatoid arthritis
• Other causes: renal failure (uremia), tumors (Hodgkin lymphoma), radiation, sarcoidosis

Tuberculosis is the most common cause of constrictive pericarditis in developing countries.

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Acute pericarditis

• Low-grade intermittent fever, tachypnea, dyspnea, nonproductive cough
• Chest pain: often sharp, pleuritic; improves on sitting and leaning forward
• Pericardial friction rub: high-pitched scratching sound best heard on auscultation over the left sternal border during expiration while the patient is sitting up and leaning forward
• Pericardial effusion

Constrictive pericarditis

• Symptoms of fluid overload (backward failure)
  • Jugular vein distention, ↑ jugular venous pressure
  • Kussmaul sign
  • Hepatic vein congestion → hepatomegaly, painful liver capsule distention, hepatojugular reflux
  • Peripheral edema; or anasarca, ascites with abdominal discomfort
• Symptoms of reduced cardiac output (forward failure)
  • Fatigue, dyspnea on exertion
  • Tachycardia
  • Pericardial knock: sudden cessation of ventricular filling during early diastole that is heard best at the left sternal border
  • Pulsus paradoxus: ↓ blood pressure amplitude during deep inspiration

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Acute pericarditis

The diagnosis is based primarily on a history of pleuritic chest pain and a friction rub heard on auscultation. It is supported by the following findings:

• Blood tests: CBC (leukocytosis; ), ↑ troponin I, ↑ ESR, ↑ CRP, abnormal renal parameters (BUN, creatinine, electrolytes) if caused by underlying uremia
• Typical ECG changes: not present in uremic pericarditis
  • Stage 1: initial diffuse ST elevations; , but ST depression in aVR and V1; PR segment depression
  • Stage 2: ST segment normalizes in ∼ 1 week.
  • Stage 3: inverted T waves
  • Stage 4: ECG returns to normal baseline (as prior to onset of pericarditis) after weeks to months.
• Echocardiography: often normal; possibly signs of effusion
• Chest x-ray normal

Constrictive pericarditis

• Chest x-ray (best initial test); , CT, and MRI: pericardial thickening and calcifications, normal cardiac silhouette
• Echocardiography
  • ↑ Pericardial thickness
  • Abnormal ventricular filling with sudden halt during early diastole
  • Pronounced respiratory variation in ventricular filling: across the tricuspid valve, velocity of blood flow increases with inspiration by > 40% (due to constriction), whereas across the mitral valve, velocity of blood flow decreases with inspiration by > 25% (due to a decrease in relaxation of the left ventricle)
  • Moderate biatrial enlargement
  • Excludes right ventricular hypertrophy and cardiomyopathy
• ECG shows no conclusive findings.
  • Atrial fibrillation can occur in severe disease.
• Cardiac catheterization
  • Elevated diastolic pressures in the left and right ventricles with diastolic equalization
  • Mean right arterial pressure > 15 mm Hg
  • Right ventricular end-diastolic pressure > ⅓ of the systolic pressure
  • Square root sign
    • Also known as dip-and-plateau waveform
    • Sudden dip of the right and left ventricular pressure in early diastole followed by a plateau during the last stage of diastole

References:^{[8][5][6][7][10][11][12][13][2]}