Circadian rhythms in cardiovascular function.

This short overview discusses circadian rhythms observed in cardiovascular events such as myocardial ischaemia and myocardial infarction, which occur most frequently in the morning. Changes in the frequency of occurrence seem to be related to, and may result from, circadian rhythms in factors such as heart rate, blood pressure, coronary artery tone, platelet adhesiveness and blood fibrinolytic activity, which could be involved in triggering myocardial ischaemia or infarction. Consideration of the circadian rhythm of myocardial ischaemia and serious cardiovascular events may be important when medical therapy is selected.