Q. Pathophysiology of Cardiac tamponade?

Progressive increase in pericardial fluid results in progressive increase in intrapericardial pressure, till a critical volume is reached beyond which small increases result in significant increase in intrapericardial pressure. The compliance of the pericardium and rate of accumulation of fluid decides the critical volume. The increase in intrapericardial pressure results in decreased ventricular distension and decreased ventricular filling. This results in decrease in stroke volume. In order to maintain cardiac output, there will be sinus tachycardia. In severe cardiac tamponade, this compensatory mechanism will be inadequate resulting in low output, hypotension, hypoperfusion, and shock state. The reduction in coronary circulation can further reduce the myocardial performance.