Circadian variations in cardiovascular disease
Richard Clinton Becker, MDAddress reprint requests to R.C.B., The Department of Cardiovascular Medicine, University of Massachusetts Medical Center, Worcester, MA 01605.
Jeanne M. Corrao, RN, MS
Circadian variations have been observed for a number of hemodynamic and cardiovascular events including heart rate, systemic blood pressure, coronary artery blood flow, ischemic cerebrovascular accidents, myocardial ischemia, myocardial infarction, and sudden cardiac death. In addition, circadian variations in platelet response to aggregating stimuli, plasma fibrinogen, coagulation factor concentration, and intrinsic fibrinolytic activity (as determined primarily by inhibitors of plasminogen activation) have been documented. Observed periodicities in thrombogenic capacity and cardiovascular events seem to correlate directly, suggesting a cause-effect relationship. Circadian variations in thrombotic tendency may influence the therapeutic response to anticoagulants and thrombolytic agents, particularly rt-PA. This area of cardiovascular disease is of profound clinical importance and warrants further investigation.