Pericardial effusion
Pericardial effusion refers to accumulation of pathological amounts of fluid in the pericardial cavity. In physiological cases there is 15-50 mL of fluid in the cavity. It may cause cardiac tamponade, which is an emergency. If the fluid is blood it's called haemopericardium.
Etiology
- Pericarditis
- Tuberculosis
- Following heart surgery
- Thoracic injury
- Metastasis
Pathomechanism
In cases where the fluid accumulates quickly, only small amounts of fluids (100-150 mL) are required to cause symptoms. Symptoms occur because the pressure in the pericardial cavity increases, preventing diastolic filling of the heart and causing cardiac tamponade.
In cases where it accumulates slowly, up to 2 litres may accumulate before symptoms occur. This is because the pericardial sac adjusts and expands to accomondate the increased fluid.
Clinical features
Pericardial effusion itself is usually not symptomatic until it reaches the point where cardiac tamponade develops.