Acute cardiac tamponade is life threatening and requires prompt pericardial drainage. This review explains the manifestations of tamponade, including a presentation in which the diagnostic finding of pulsus paradoxus is absent, and variant forms, such as low-pressure tamponade and regional tamponade. Cardiac tamponade is life-threatening, slow or rapid compression of the heart due to the pericardial accumulation of fluid, pus, blood, clots, or gas, as a result of effusion, trauma, or rupture of the heart. 1 , 2 Because the causes of pericardial disease 1 and thus of tamponade are diverse, clinicians must choose the most probable diagnosis, always anticipating surprises. Thus, traumatic tamponade is most apt to follow cardiac surgery, and tuberculous tamponade is relatively common in Africa but rare in the United States. Understanding the physiological changes produced by tamponade is essential to diagnosis and treatment. 3 – 12 The primary abnormality is rapid . . .