Ultrastructure of the human myocardium after intermittent ischemia compared to cardioplegia

A lot of reports informed about the detrimental effects of intermittent ischemia nevertheless this method is still used during coronary surgery. We investigated the myocardial protection due to cardioplegic arrest compared to intermittent ischemia in 120 patients undergoing coronary surgery. In all patients we took myocardial biopsies from the left ventricle before and after ischemia. Electron microscopic studies of all biopsies were performed and the degree of ultrastructural alteration was determined. The ischemic period in the cardioplegic group was 61 +/- 15 minutes and in the group with intermittent ischemia the total ischemic time was 45 +/- 21 minutes. After ischemia the myocardium showed most time only damage of moderate or light degree, while after intermittent ischemia the most biopsies showed severe ultrastructural damage. From our results we conclude, that intermittent ischemia is unable to protect the myocardium in a sufficient amount and should therefore no longer be used as a method of myocardial protection.