Importance of cardiovascular reflexes in disease.

Circulatory reflexes are important in effecting rapid distribution of blood flow and an adequate driving pressure during adjustment to the stress of exercise, posture change, and other environmental challenges. Their primary evolutionary role may be a response to the extreme stress of hemorrhage. Derangements of reflex control may lead to adverse effects on organ blood flow, particularly renal blood flow; adjustments appropriate for support of the circulation during hemorrhage may be inappropriate in congestive heart failure. The balance between one control system and another may be altered by disease. Arterial baroreflex control of the circulation is impaired in hypertension, but may be partially compensated by increased gain in cardiopulmonary reflexes. Changes in autonomic balance in acute myocardial ischemia may be important in the mechanism of sudden death. Physical training can favorably modify arterial baroreflex function and adds to the evidence in favor of active rehabilitation after infarction.