Pathogenesis and morphogenesis of microcirculatory disorders in myocardial infarction. Clinical and ultrastructural...

Major advances in the understanding of myocardial infarction (MI) have been made on animal models of ischemia and infarction. We performed ultrastructural examinations of the hearts of 36 patients who died during the acute phase of MI. Tissue for investigation was obtained by express necropsy immediately after death at the clinic. All components of the microcirculatory system of the heart were damaged during the acute phase of MI. Coronary thrombosis led to arteriolar spasm and intravascular blood coagulation in the vicinity of the damaged artery. Microvessels reduction in ischemic, necrotic, and near-infarct zones was caused by endothelial cell injury and rheological disturbances. Thrombocytes played a decisive role in thrombus formation and arteriolar constriction. Leukocytes nearly always impaired the microhemodynamics in ischemic zones due to their size and rigidity. Microcirculatory disorders seemed to precede myocardial cell injury and death.