Effect of Hypothermic Anoxic Arrest on Myocardial Contractility in the Isolated Blood-Perfused Canine Left Ventricular Muscle

The present studies were performed to evaluate the protective effect of topical hypothermia on anoxic heart. The myocardial protection was assessed by myocardial contractility in the isolated blood-perfused electrically driven canine left ventricular muscle. The isometric tension and the rate of rise of tension development (dT/dt) were measured before and after hypothermic anoxic arrest and percent recovery of these values was used as a parameter of myocardial contractility. The percent recovery rates of 100, 95, 90, and 65 were obtained after acute anoxia of 90, 120, 150, and 180min, respectively at the myocardial temperature of 17°C. These data suggest that the safe limit of acute anoxia at the myocardial temperature of 17°C is defined as 90min in this experimental model and it can be extended to 120min at the myocardial temperature below 17°C.