An angiographic study of intracardiac coronary arteries from human autopsy hearts: their clinicopathologic significance and characterization during transmural myocardial infarction.

In this study of human autopsy hearts, coronary arteries were divided by morphologic criteria into classes A (branching-type) and B (straight-type) arteries. Infarcted hearts and normal hearts were investigated mainly by means of coronary angiography, as well as by gross and histologic examinations. Transmural myocardial infarction originated in the inner half of the myocardial layer, which was predominantly supplied by class A arteries, followed by gradual extension to the outer layer. The early infarcted focus revealed an angiographically avascular state. This may have been the result of shrinkage of the peripheral branches of class A arteries due to increased extravascular resistance rather than to arteriolar obstruction by small thrombi and/or leukocyte plugs. By contrast, class B arteries remained patent and were almost entirely free from such phenomena. They usually penetrated the infarcted focus to drain into the papillary muscles and trabeculae carnae. As the process of myocardial infarction progressed, various patterns of vascular reactions corresponding to the healing phase were demonstrated by these branches within the infarcted foci. The passive response of class A arteries during acute ischemia characterized the early myocardial lesion. Subsequently, neovascularization from the surviving class B arteries in the infarcted focus occurred as a part of the formation of granulation tissue. Newly formed small arteries from class A arteries also participated in this reaction at the marginal area of the lesion. These well-coordinated vascular reactions revealed in greater detail the initiation and progression of the healing process and were reflective of the clinical prognosis.