III. Local cardiac hypothermia: experimental comparison of Shumway's technique and perfusion cooling.

A model of the thermal conditions of the heart during ischemic arrest was used to study the efficiency of Shumway's technique of topical hypothermia. Cooling was improved by increasing the flow of cold saline to 350 ml per minute, reducing the saline temperature, lifting the posterior left ventricular wall away from the pericardium, and irrigating the left ventricular cavity. Perfusing the coronary circulation with cold fluid cooled the heart eight times faster than did surface irrigations by Shumway's technique.