Impact of Exercise-Induced Coronary Vasomotion on Anti-Ischemic Therapy
Coronary artery disease(2000)
摘要
Coronary vasomotion has an important role in the regulation of myocardial perfusion. During dynamic exercise, normal coronary arteries dilate, whereas stenotic arteries constrict. This exercise-induced vasoconstriction has been associated with the occurrence of myocardial ischemia and has been believed to be the result of endothelial dysfunction, with a reduced release or production of EDRF, increased sympathetic stimulation, enhanced platelet aggregation with release of thromboxane A2 and serotonin, or a passive collapse of the disease-free wall segment within the stenosis (the Bernoulli effect), or a combination of any of these. More recently, it has been realized that pharmacological treatment might prevent exercise-induced vasoconstriction and, thus, reduce myocardial ischemia and the occurrence of angina pectoris. Vasodilators such as nitrates, calcium antagonists or alpha-receptor blockers dilate the coronary arteries and prevent coronary stenosis narrowing during exercise. In contrast, beta-blocking agents are associated with coronary vasoconstriction at rest, but--conversely--can induce coronary vasodilatation during exercise. Pharmacological treatment in patients with stable angina pectoris may improve myocardial ischemia by reducing pre- and afterload, myocardial contractility, oxygen consumption, and vasomotor tone. However, coronary collateral perfusion can modify these effects by shunting blood from the non-ischemic to the ischemic region (collateral flow) or by shunting blood from the ischemic to the non-ischemic zone (coronary steal phenomenon). Typically, a steal phenomenon has been reported in patients receiving either dipyridamole or calcium antagonists, whereas a reversed steal has been described after beta-blockade, with an increase in contralateral tone shunting blood from the non-ischemic to the ischemic zone (reverse steal phenomenon).
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关键词
coronary vascular tone,coronary artery disease,stable angina pectoris
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