​Cardiac tamponade occurs when fluid builds up in the space between the outer sac covering the heart (pericardium) and the heart muscle (myocardium). The excess fluid puts pressure on the heart, causing the ventricles (large heart chambers) to be unable to expand fully. Less blood leaves the heart and blood pressure decreases.

​One symptom of cardiac tamponade is a sharp, stabbing chest pain that radiates to the neck, shoulder, back or abdomen. Other symptoms include difficulty in breathing, low blood pressure, fainting and swelling of the abdomen.

​Cardiac tamponade can occur through chest trauma or pericarditis. It can also occur due to heart disease and heart attack.