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Classify pericarditis. Describe cardiac tamponade and constrictive pericarditis.

Pathology · 2nd Professional — Para-Clinical

Definition and Classification

Pericarditis is inflammation of the pericardium, which may be acute or chronic, and is classified by the nature of the exudate.

Type	Exudate	Causes
Serous	Clear, protein-poor	Viral infection, rheumatic fever, SLE, uraemia, tumour
Fibrinous and serofibrinous — the commonest	Fibrin-rich; gives the "bread and butter" appearance and a friction rub	Acute myocardial infarction, dressler syndrome, uraemia, rheumatic fever, radiation, trauma, viral
Purulent (suppurative)	Frank pus	Bacterial — by direct spread, haematogenous seeding, or after surgery
Haemorrhagic	Blood mixed with fibrin or pus	Tuberculosis and malignancy — important in India; also after cardiac surgery
Caseous	Caseous material	Tuberculosis — the usual antecedent of constrictive pericarditis

Clinical Features of Acute Pericarditis

Sharp, pleuritic retrosternal chest pain, relieved BY sitting forward and worsened by lying flat — the position dependence distinguishes it from infarction
Pericardial friction rub — a scratchy sound, classically with three components, heard best at the left sternal edge with the patient leaning forward
ECG — widespread concave ("saddle-shaped") ST elevation with PR depression, in contrast to the localised convex elevation of infarction
Fever and a raised ESR

Pericardial Effusion and Tamponade

Normal pericardial fluid is about 30–50 mL
What matters is the rate of accumulation, not the volume — 150–200 mL accumulating rapidly causes tamponade, whereas 1–2 litres accumulating slowly may not
Cardiac tamponade — the fluid restricts diastolic filling
BECK triad — hypotension, raised jugular venous pressure, and muffled heart sounds
Pulsus paradoxus — an inspiratory fall in systolic pressure of more than 10 mmHg
Chest radiograph shows a globular "water-bottle" heart; ECG shows low voltage and electrical alternans
Treatment is urgent pericardiocentesis

CLINICAL PEARL

Rate matters more than volume, and that follows from the pericardium’s mechanics. It is a stiff fibrous sac that stretches only slowly. Given weeks it accommodates litres; given minutes it cannot accommodate a cupful. This is why a stab wound causes tamponade with very little blood while a malignant effusion may be enormous and well tolerated.

Constrictive Pericarditis

Dense fibrous or calcified scarring encases the heart and prevents diastolic filling
Tuberculosis is the leading cause in India; elsewhere, previous cardiac surgery, radiation and idiopathic causes predominate
Features — raised jugular venous pressure with a prominent y descent, kussmaul sign (JVP rising on inspiration), hepatomegaly, ascites out of proportion to peripheral oedema, and a pericardial knock
"concretio cordis" — a heavily calcified, adherent pericardium; calcification may be visible on a plain radiograph
Treatment is surgical pericardiectomy, which is curative — hence the importance of distinguishing it from restrictive cardiomyopathy

Applied Aspects

Distinguish pericarditis from myocardial infarction — the position-dependent pain, the rub, and the widespread concave ST elevation with PR depression
Tuberculous pericarditis should be considered in every case in India, and is treated with antituberculous therapy plus corticosteroids to reduce constriction
Uraemic pericarditis is an indication for dialysis, and improves with it
Dressler syndrome appears weeks after an infarct and is autoimmune; it responds to aspirin and colchicine, and anticoagulants are avoided
Never give anticoagulants in acute pericarditis if effusion is present, because of the risk of haemorrhagic tamponade

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