THE ADVISABILITY of operation in many patients is based on an assessment of the cardiac status.1-3 If operation is directed at the heart itself, preoperative study of the patient often includes a detailed hemodynamic evaluation by cardiac catheterization. On the other hand, evaluation of general surgical patients rarely includes cardiac catheterization; considerable reliance is placed on an estimate of exercise tolerance and the presence or absence of overt cardiac failure.
Since pulmonary disease or disturbance in many other organ systems may impair exercise capacity when the heart appears to be functioning normally, we need criteria more specific than simple exercise tolerance to estimate reserve capacity of the heart. How can we quantitate the pumping capability of the heart and relate this to the probability of survival in the face of anticipated operative stress? Techniques for such assessment, previously confined to the experimental laboratory, are now applicable to patients in