This new method of myocardial protection was used to prevent complications of cardiac ischaemia during clamping of the aorta. 4 litres of Ringer lactate at 4 degrees C are used to perfuse the coronary arteries and produce a total, uniform and deep fall of all the pericardial and myocardial system. This results in a flat electrocardiogram, i.e. the interruption of electrical activity of the cardiac cells. This effect persists until the aortic clamp is released which results in reoxygenation, a rise in temperature and the restoration of function. The method has been used in more than 250 operations with extracorporeal circulation (valves, bypass procedures, transplants). Up until the present, it has proved superior to techniques of coronary perfusion or hypothermia obtained using Shumway's technique.