MYOCARDIAL DEPRESSION AFTER ELECTIVE ISCHEMIC ARREST - SUBCELLULAR BIOCHEMISTRY AND PREVENTION

  • 1 January 1979
    • journal article
    • research article
    • Vol. 77  (4) , 608-618
Abstract
The hemodynamic and cardiac biochemical effects of global ischemic arrest during cardiopulmonary bypass (CPB) were studied in 54 dogs and compared to 7 dogs without ischemic arrest. Ischemic arrest alone reduced the 1st derivative or left ventricular force of contraction (LV dF/dt) to 52% of control 10 min after resuming function and to 64% after 1 h of reperfusion. Cardiac output was depressed to 52% of control after 10 min of reperfusion and to 74% of control after 60 min of reperfusion. In 6 animals, moderate hypothermia (26.degree. C) resulted in no protection of cardiac function from ischemic arrest but profound hypothermia to 18.degree. C resulted in values of LV dF/dt and cardiac output nearly equivalent to the CPB control group (no arrest). A continuous infusion of a hyperkalemic hypothermic solution slightly improved the degree of protection over hypothermia alone. The sarcoplasmic reticulum (SR) isolated from hearts which underwent 60 min of ischemic arrest bound significantly less Ca when the isolation was done after 10 min of reperfusion and when it was done after 60 min of reperfusion. The time to spontaneous release of Ca from the SR was significantly longer. Moderate hypothermia did not result in improved SR function but deep hypothermia induced by local cooling or by hypothermic K infusion retained SR function at normal levels. Oxidative phosphorylation of mitochondria isolated after 60 min of reperfusion was depressed. The mitochondrial respiration rate after normothermic ischemic arrest was 155 natm O2/min vs. 237 natm for hypothermic hyperkalemic group. Respiratory control index was 5.5 for the normothermic group vs. 9.4 for the hypothermic group. Hypothermia, effected by surface cooling or by hypothermic K infusion, allowed full recovery of hemodynamic and biochemical functions within 1 h of reperfusion.