10th May 2025

Cardiac Tamponade

Fluid accumulation from pericardial effusion causes increased pressure in the pericardial sac, causing  impaired diastolic filling of the left and right heart. Reduced filling of the right heart can cause venous  congestion, and reduced filling of the left heart can cause a drop in stroke volume. Increased pressure in  the pericardial sac may cause compression of the heart, especially the right heart, due to a thinner wall.  Impaired diastolic filling of the right heart causes venous congestion. Reduction in the diastolic filling of  the left ventricle results in decreased cardiac output and eventually shock. This is a medical emergency  called cardiac tamponade. Cardiac tamponade can occur with small rapid increases in volume of the  pericardial fluid (around 100-150ml), with a classical example being from a traumatic cardiac injury  (blunt or penetrating trauma). However, in chronic settings where there is gradual build-up such as in autoimmune disease, neoplasms or chronic pericarditis, the pericardial effusion may become 1L – 2L in  size before it causes cardiac tamponade.