Occurrence and significance of coagulative myocytolysis in the specialized conduction system: Clinicopathologic observations

Abstract

In 5 of 18 selected human hearts (15 from patients with early myocardial infarction and severe coronary arterial obstruction), coagulative myocytolysis (myofibrillar degeneration with contraction bands) was demonstrated in the specialized conduction tissue. Its morphologic peculiarities, apparently inherent in the number and arrangement of the affected myofibrils in each type of specific myocell, are described. In nine cases the ordinary cardiac muscle was also involved; in all hearts concomitant changes were present. The debated toxic catecholamine and anoxic aspects of coagulative myocytolysis are briefly reviewed in light of the finding that specialized tissue seems to withstand myocytolytic damage (or any ischemic-anoxic injury) better than ordinary myocardium. This may also explain why coagulative myocytolysis is observed less frequently and evidently in specific rather than in ordinary myocells. Clinicopathologic comparisons focused on arrhythmias, although hampered by inadequacies in routine electrocardiographic documentation, suggest that coagulative myocytolysis of the conduction system may be relevant to life-threatening disturbances in impulse formation and conduction. These data, with their bearing on important current problems in cardiologic emergencies, deserve better morphopathophysiologic assessment.