title: Determination of maximal ischemic tolerance of the human heart by ultrastructural recording of preischemic degree of myocardial hypertrophy and degeneration.
abstract: Three biopsies were taken transmurally in different time intervals (before and after ischemia and during the reperfusion phase) from 20 patients undergoing open-heart operation for acquired valvular heart disease, and the myocardial cylinders were examined with the electron microscope. They were scrutinized to see if there is a relationship between the degree of hypertrophy and degeneration before ischemia and the extent of ischemic damage after a certain ischemia period, and between the damage before ischemia and the postoperative outcome of the patients. Our results show that the ischemic changes are not dependent on the preischemic extent of hypertrophy and degeneration. It seems that they are mainly dependent on the duration of ischemia because the degree of ischemic damage increases with prolongation of the ischemia interval. However, a good correlation was found between the preischemic changes and the postoperative outcome. Especially the combination of marked hypertrophy and the appearance of degenerative signs in the biopsy taken before ischemia seems to predestine a bad postoperative course. Therefore, it can be concluded that the total damage to the myocardial cells, which results from the sum of previous damage (hypertrophy and degeneration) and ischemic alterations, is responsible for the postoperative outcome.
mesh_terms: D006332:Cardiomegaly / Q000473:pathology*; D005260:Female; D006324:Heart Arrest, Induced / Q000009:adverse effects*; D006349:Heart Valve Diseases / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000648:ultrastructure*; D011379:Prognosis