Congenital aortic sinus aneurysm causing sudden unexpected death in a 56-year-old woman

Sudden unexpected death due to hemopericardium generally has 2 main causes, rupture of the ascending aorta or rupture of a transmural myocardial infarct. We report an unusual cause of fatal hemopericardium in a 56-year-old woman that occurred in the setting of a motor vehicle mishap.At autopsy, 300 mL of blood were present in the pericardial sac, due to rupture of a previously undetected congenital aortic sinus aneurysm. The low velocity of the automobile at the time of impact with a fence, and the absence of vehicle-related trauma, led to the conclusion that rupture of the aneurysm caused the motor vehicle mishap, rather than vice versa. Because of the typically silent nature of such aneurysms, it is likely that their rupture will occur out-of-hospital and require a forensic investigation.