Unexpected sudden death in an otherwise healthy individual has two main causes. The most important is drug misuse or over dosage especially with stimulants such as in diet-weight loss pills. The other main concerns are inborn or inherited conduction defects in the heart that predispose young athletes, and others at times, to sudden onset of an arrthymia. Susceptibility to this may have a genetic basis and other close relatives may want to check out their own cardiac function. Several other causes of sudden death would include massive pulmonary embolus or premature arteriosclerosis that involves the coronary arteries, but these should be readily detected on the basis of personal history and clinical abnormalities. Prior injury may be a factor if prolonged leg rest had occurred, which predisposes the legs to venous stasis and pulmonary embolus. The heart is fairly resilient to indirect injuries unless adjacent tissue is damaged. This could cause pericarditis and in turn this reduces cardiac performance. In some cases sudden death cannot be predicted or explained, and one might guess that the cause was a sudden arrthymia.