STRUCTURAL CORRELATES OF REGIONAL MYOCARDIAL DYSFUNCTION IN PATIENTS WITH CRITICAL CORONARY-ARTERY STENOSIS - CHRONIC HIBERNATION

The morphologic changes in the myocardium of hypocontractile segments, especially the possible structural counterparts underlying chronic is chemia, are not well documented. Light and electron microscopy was per formed on myocardium derived from the anterior wall of the left ventri cle of 98 patients during coronary artery bypass grafting. Wall motion data were collected from the region corresponding to the biopsied zon e. The changes seen in a substantial part of the cardiomyocytes corres ponded to ''dedifferentiation'' rather than degeneration characteristi cs. The affected cardiomyocytes showed a partial to complete loss of s arcomeres, sarcoplasmic reticulum, and T-tubules and presented abundan t plaques of glycogen, strands of rough endoplasmic reticulum, lots of minimitochondria, and a tortuous nucleus. The volume of the cells was similar to that of normal cells. The number of the affected cells was consistently higher in endocardial parts than in epicardial ones. The cell changes occurred in the myocardium of patients both with and wit hout a previous Q-wave infarction. There was a significant relation be tween anterior wall motion abnormalities and the incidence of affected cells in the endocardium, but not in the epicardium. A significant re lationship was found in noninfarcted patients between the presence of affected cells and the amount of connective tissue. Furthermore, in th ese patients the number of affected cells depended on the degree of st enosis. It is proposed that segments in which these structural changes prevail will not recover immediately after revascularization but that they might show a delayed recovery of function, because structural re modeling requires time in order to regain sufficient contractile mater ial.