The serious effects of coronary artery disease on the heart are due to an inadequate blood supply to the heart muscle. Usually the reduction in the blood supply is associated with a diminution in the caliber of the coronary arteries, either local or general, by atherosclerosis. On the other hand, there are conditions which, even in the presence of normal coronary arteries, may result in a decreased blood supply to the myocardium.1
It is possible, also, that myocardial ischemia may result from temporary spasm of coronary arteries. This could take place, as a result of a decrease in or loss of the dilator response of the coronary arteries to physiologic stimuli, whether the arteries were atherosclerotic or normal.
Although it has been impossible so far to reproduce experimentally true human coronary sclerosis, it is possible to simulate the effects of the resulting myocardial ischemia by ligation of one or