The Experimental Production of Intercoronary Arterial Anastomoses and their Functional Significance

Abstract

Animal experiments were done to learn the degree of coronary narrowing required to produce the larger intercoronary collateral channels, their speed of development, and the degree of protection afforded the myocardium. Twelve or more days of 75 per cent narrowing were required to produce sufficiently rich anastomotic communications to protect the myocardium from damage, and to permit survival after superimposed acute complete occlusion. The physiologic and pathologic significance of the intercoronary collateral communications and the clinical implications in coronary artery disease are discussed.T HE CLINICAL manifestations of acute myocardial infarction are no longer regarded to be solely the result of an acute occlusion of a coronary artery. In some instances, acute myocardial infarction occurs in the absence of fresh narrowing or occlusion'-while in other hearts the effects of acute occlusion may be partly neutralized by the presence of collateral circulation consequent to previous narrowing. Thus, acute myocardial infarction is to be regarded rather the resultant of two opposing processes; namely, the obstruction to blood flow by occlusive processes, and the compensatory development of collateral circulation which serves to offset the dire effects of coronary narrowing and occlusion.Despite excellent studies of the collateral coronary circulation, the speed with which interarterial connections develop and the degree to which they protect the myocardium are imperfectly understood. Clinical and pathologic data on hearts with old coronary occlusion and with collateral circulation do not yield decisive answers. On examining such a human heart post mortem, only the net end result of the obstructive process and the compensatory bypasses is witnessed; one cannot determine accurately, even by microscopic study, how long previously the narrowing or complete occlusion

Myocardial morphometric characteristics in swine.

“…We nave used swine as a model of cardiac hypertrophy (White et al, 1979) since its response to exercise stress is similar to that in humans. Also, the swine has a coronary artery distribution similar to that of the normal human (Lumb and Hardy, 1963), a limited coronary collateral circulation (Blumgart et al, 1950), and a similar ratio of heart weight to body weight to that of man (Schaper, 1971). Therefore it is an appropriate model for comparison to man (Blumgart et al, 1950; Lumb andSingletary, 1961;1962;Lumb and Hardy, 1963;Kong et al, 1969).…”

“…Also, the swine has a coronary artery distribution similar to that of the normal human (Lumb and Hardy, 1963), a limited coronary collateral circulation (Blumgart et al, 1950), and a similar ratio of heart weight to body weight to that of man (Schaper, 1971). Therefore it is an appropriate model for comparison to man (Blumgart et al, 1950; Lumb andSingletary, 1961;1962;Lumb and Hardy, 1963;Kong et al, 1969). However quantitative ultrastructural studies of the normal and hypertrophic heart have been conducted mainly in smaller species, e.g., rats (Page et al, 1971;Anversa et al, 1976Anversa et al, , 1978Legato, 1976; Wendt-Gallitelli and Jacob, 1977;McCallister et al, 1979;Tomanek et al, 1979), rabbits (Anversa et al, 1971;Goldstein et al, 1974), hamsters (Colgan et al, 1978), cats (Sheridan et al, 1977), and ferrets (Breisch et aL, 1980).…”

Correlation of regional myocardial blood flow and function with myocardial infarct size during acute myocardial ischemia in the conscious pig.

“…9 The pig, therefore, may be a more appropriate model of acute myocardial ischemia for comparison with man. 8 This study was designed to examine the relationship of regional myocardial blood flow (RMBF) and function in the functionally defined marginal zone after coronary artery occlusion in the conscious pig.…”

Stimulation of Interarterial Coronary Anastomoses by Experimental Acute Coronary Occlusion

“…Similar experimental observations were made by Blum, Schauer, and Calef,13 by Burchell,14 and by us. 3 The clinical counterpart of these experiences, i.e., the occurrence of complete coronary artery occlusions without myocardial infarction, has been noted by Saphir In the present study, as in our other studies, the iniject ion mass never traversed pericardial adhesions to adjacent structures such as the venae cavae, the aorta, the pulmonary vessels, and the reflections of the parietal pericardium, despite the presence of fine extracardiac communlicating vessels that may be demonstrated anatomically by the injection of india ink or similar suspensions. Similarly, if coronaryluminal communications of smaller size are present, they are like the normal fine interarterial coronary and extracardiac communications in that they are of little funitioiial significance in safeguarding the myocardium after acute corollary occlusion.…”