RESUMO
When the aorta must be temporarily occluded at the suprarenal or supraceliac levels during surgery, the resulting large increase in afterload may make the myocardium ischemic, even though systemic and pulmonary artery pressures and cardiac output are maintained at normal levels. These traditional indices of myocardial well-being do not appear to be sufficiently sensitive, since cardiac complications are still the most frequent cause of perioperative death and morbidity after aortic reconstruction. To evaluate two-dimensional transesophageal echocardiography as a monitor of myocardial well-being, we studied 24 American Society of Anesthesiologists physical status class III or IV adult patients who were undergoing aortic reconstruction and occlusion at the supraceliac (n = 12), suprarenal-infraceliac (n = 6), or infrarenal (n = 6) level. In addition to traditional monitors, we used a gastroscope tipped with a special 3.5 MHz two-dimensional echocardiographic transducer (Diasonics) that was placed in the esophagus to give a cross-sectional view of the left ventricle through the base of the papillary muscles. The hemodynamic effects of clamping the aorta were managed by administration of vasodilating drugs, anesthetics, and fluids to keep systemic and pulmonary arterial pressures normal. Occlusion at the supraceliac level caused major increases in left ventricular end-systolic and end-diastolic areas, decreases in ejection fraction, and frequent wall motion abnormalities; these changes were not detected by conventional monitoring devices. Occlusion at the suprarenal-infraceliac level caused similar but smaller changes, and occlusion at the infrarenal level caused only minimal cardiovascular effects. We conclude that the two-dimensional transesophageal echocardiogram offers promise as an intraoperative monitoring device.