Idiopathic (often presumed post-viral)
Infection: Viral most common--> Coxsackie, HSV, HIV; Bacterial (extension from pneumonia); TB (miliary or extension from pneumonia), Acute Rheumatic Fever
Autoimmune: Lupus, Rheumatoid Arthritis, Scleroderma, Mixed Connective Tissue d/o, Stills Disease
Toxic/Metabolic: Uremia, hypothyroidism
Meds: Hydralazine, procainamide, phenytoin, isoniazid, penicillins, others
Radiation or cancer involving the mediastinum
Post MI (early or late)
Post cardiac surgery

May be tachycardic - depending on degree pain/inflammation; also if effusion, depressed ventricular function
Often pericardial friction rub present (3 components)
If effusion→ may have decreased heart sounds
If tamponade→ elevated jvp, soft heart sounds, elevated hr, low bp, pulses paradoxus (more then 10 point difference between SBP on expiration v inspiration), sometimes palpable pulse volume varies