A clinical method for detecting subendocardial ischemia after cardiopulmonary bypass

Subendocardial ischemia with consequent subendocardial necrosis is a frequent cause of death after cardiopulmonary bypass. The problem is caused by an inequity in the oxygen requirements of the subendocardium and the available blood supply. We have developed a means of detecting ischemia early in the postperfusion period. Using an analogue computer, we determine the endocardial viability ratio (EVR). This value may decrease before either systemic or central venous pressure changes. Thus the ratio can reflect early the danger of subendocardial ischemia. Another advantage is that equipment now common in coronary care units can be used to determine the EVR.