To the Editor:—
The opinion that angina pectoris is not related to the ischemia of the heart, but, on the contrary, to vasodilation of the coronary arteries, which is associated with a greater increase of myocardial demands than is met by this increase of blood supply, is based on pathophysiological, clinical, and therapeutical data.
The coronary arteries, as we know, are under the control of autonomic nervous system, the parasympathetic being vasoconstrictive to the coronary vessels and the sympathetic being vasodilatative. The vasoconstriction of these vessels of parasympathetic origin cannot result in angina because this vasoconstriction is associated with a decrease of myocardial needs (anabolic action) and therefore it does not result in coronary insufficiency which is the cause of angina. On the contrary, the vasodilation of the coronary arteries of sympathetic origin which is insufficient to cover the increase of myocardial demands (catabolic action) can be the cause