Anatomy and quantification of myocardial cell death.

Abstract

Irreversible damage of the myocardial cells may show different morphologic aspects in relation to the type of dysfunction of their contraction-relaxation cycle. Attenuation of the muscle fibers with elongation of the sarcomeres and nuclei are the earliest modifications (systolic paradoxical bulging and stretching by the intraventricular pressure) when the myocells stop their function in irreversible relaxation. This 'atonic' death is pathognomonic of myocardial infarction (infarct or coagulation necrosis) and the lesion evolves with typical structural changes. An opposite and entirely different morphologic pattern is seen in the 'tetanic' death in which the myocardial cells arrest in irreversible contraction (coagulative myocytolysis or contraction band necrosis). Segmental (paradiscal bands) or pancellular hypercontraction with extreme shortening of the sarcomeres and subsequent myofibrillar rhexis alternated with irregular cross band formations (holocytic bands) are characteristic of this necrosis seen in numerous human and experimental conditions and specific of catecholamine toxicity. The third type of damage is observed in low output syndromes in which increasing edematous vacuolization and disappearance of the myofibrils (colliquative myocytolysis) are the main structural alterations. They are suggestive of progressive functional reduction leading to dilatative insufficiency ('failing' death). These clear-cut morphofunctional patterns indicate distinctive biochemical impairments and pathogenesis. In particular their frequent presence in and possible association with the different aspects of the ischemic heart disease presuppose other non-ischemic mechanisms responsible for complications and death in this modern epidemic.