Coronary Vasomotor Tone: Implications in Ischemic Heart Disease
In the early 1950’s, the increase in myocardial oxygen demand was seen as the main mechanism responsible for episodes of angina pectoris . The coronary stenosis was indeed considered as a fixed obstruction on the epicardial vessel, limiting the capacity of the coronary artery to augment coronary flow. Myocardial ischemia was assumed to occur for a given and very reproducible level of myocardial oxygen demands. However, this concept was progressively refuted by the development of coronary angiography. In 1959, Prinzmetal et al.  described a group of patients with typical angial pain which was provoked by large vessel coronary spasms, pointed out by coronary angiography. Moreover from angiographic studies , even severe atherosclerotic epicardial vessels appear to retain the capacity to dilate and to constrict. Pharmacological studies of isolated human coronary arteries  have also shown that severe atherosclerotic segments are not rigid structure.
KeywordsAngina Pectoris Unstable Angina Myocardial Blood Flow Coronary Blood Flow Chronic Stable Angina
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