COMPENSATORY ADJUSTMENTS IN THE STRUCTURE OF CORONARY ARTERIES OF THE HEART WITH STENOTIC ATHEROSCLEROSIS

Adjustments within the coronary arterial system that compensate for stenotic atherosclerosis include hypertrophy of larger coronary arterial branches unaffected by atherosclerosis that undertake supply of blood to an anemic myocardial area; development of collateral circulation; extension of the "paravasal" bed; formation of short anastomoses; and wide recanalization of thrombi. A combination of special technics devised for this investigation included fixation of coronary arteries with formol under pressure approximating the level of diastolic blood pressure, followed by their injection with an opaque mixture or colored gelatin; angiographic examination and dissection; and microscopic examination of numerous cross sections prepared from the whole length of major trunks and their branches. The size of atherosclerotic plaques and degree of luminal narrowing were then determined planimetrically, as a percentage of the original lumen. These studies yielded objective evidence for assessing the influence exerted by varying degrees of luminal narrowing on blood supply to myocardium as well as on development of intercoronary anastomoses, and their compensatory significance. The principal conditions bringing about insufficiency of compensatory adjustments have also been considered: progression of coronary atherosclerosis involving arterial anastomoses in the process; successive deposition of lipids over the walls of wide channels through organized thrombi, resulting in their occlusion due to secondary thrombosis; and individually inadequate development of compensatory adjustments.