Pericardial effusion

What it is

A pericardial effusion is fluid in the pericardial sac. It sits in a line with acute pericarditis on one side and cardiac tamponade on the other: pericarditis can give a new or worsening effusion, and an effusion that accumulates rapidly turns into tamponade.

The fluid is a transudate or an exudate. A new or worsening pericardial effusion is also one of the four criteria used to diagnose acute pericarditis, and at least two of the four are required:

1. Pericarditic chest pain
2. Pericardial rubs
3. New widespread ST elevation or PR depression on ECG
4. A new or worsening pericardial effusion

Causes and risk

A transudate comes from CHF, hypoalbuminemia or hypothyroid. An exudate comes from the same causes as acute pericarditis:

• Idiopathic.
• Infectious: viral (Coxsackie virus A and B, the most common, and echovirus), bacterial (S. pneumoniae, S. aureus), TB, HIV, fungal (histoplasmosis, blastomycosis).
• Post-MI: acute at 1-7 days, and Dressler's syndrome, an autoimmune reaction 2-8 weeks post-MI.
• Post-cardiac surgery such as CABG, and other trauma.
• Metabolic: uremia, which is common, and hypothyroidism.
• Neoplasm: Hodgkin's, breast, lung, renal cell carcinoma, melanoma.
• Collagen vascular disease: SLE, polyarteritis, rheumatoid arthritis, scleroderma.
• Vascular: dissecting aneurysm.
• Other: drugs such as hydralazine, radiation, infiltrative diseases such as sarcoid, and vaccination.