DETECTION AND PREVENTION OF CARDIAC DYSFUNCTION DURING AORTIC-SURGERY

Anesthesia and aortic occlusion and release all can adversely affect cardiac function during aortic reconstruction. To minimize these effects we developed on-line computerized monitoring techniques to measure systolic time intervals (STI) and compared these data with results of cardiac output, and in nine patients with pulmonary artery pressures obtained by Swan-Ganz catheters. In 35 patients, left ventricular preejection time (PEP), left ventricular ejection time (LVET), and PEP/LVET were displayed continuously in the operating room. Paired cardiac outputs, determined by dye dilution ( 26 35) or thermodilution ( 9 35) provided cardiac index and systemic vascular resistance. Pulmonary artery diastolic pressure (PADP) was taken for the assessment of preload. Heart rate and mean arterial pressure were recorded using radial artery cannulas. Characteristic changes were noted and compared during anesthesia and clamping and release of aortic occlusion. Changes in LVET were most notable with highly significant increases during aortic crossclamping. This overall effect occurred frequently in patients with EKG evidence of prior myocardial infarction ( 24 25). In 11 patients without previous myocardial infarction, LVET increased only once during aortic crossclamping. STI were clearly most sensitive for titrating both anesthetic and vasoactive drugs to minimize cardiac depression. In contrast, pulmonary artery diastolic pressures appeared more specific for alterations in blood and fluid balance. While changes in PADP were often inconclusive, changes in STI made possible rapid detection of adverse effects of anesthesia, crossclamping, and unclamping upon cardiac function. The immediate detection and treatment of changes in left ventricular function add an important safety factor in minimizing cardiac mortality of aortic surgery. © 1979.