[Pathological anatomy of the postinfarct defect of the interventricular septum]

Morphological examinations of 21 hearts of patients with myocardial infarction complicated by defects of interventricular septum were performed. The study revealed that the formation of the postinfarction defect of the interventricular septum is due to a number of factors acting simultaneously: (a) a vast zone of transmural myocardial infarction, (b) changes of the hemodynamic conditions, i. e. local increase of intraventricular pressure on the focus of necrosis, (c) mechanical factor (increased arterial pressure, physical strain, increasing cardiac insufficiency). Localization of the myocardial infarction, aneurysm, and postinfarctional defect of interventricular septum depend on the extent and level of affection of the right and left coronary arteries. The size of myocardial infarction and aneurysm is larger in the occlusion of the anterior interventricular branch of the left coronary artery and comprises 10-30% of the total area of the left ventricle than in the occlusion of the right coronary artery (8-20%). Posterior defects maybe very high complicating considerably the surgical correction of the defect. In the edges of the rhexis of 2-week duration marked processes of organization were detected, therefore operative intervention is more advantageous beginning from this period than earlier.