Relationship of regional wall motion abnormalities to hemodynamic indices of myocardial oxygen supply and demand in patients undergoing CABG surgery

Abstract

To investigate the hemodynamic correlates of perioperative regional wall motion abnormalities (RWMA), we measured wall motion continuously via transesophageal echocardiography (TEE), and related RWMA to continuously measured hemodynamic indices of myocardial oxygen supply and demand (heart rate [HR] and systemic and pulmonary arterial blood pressures). Fifty patients undergoing coronary artery bypass graft (CABG) surgery were studied throughout the prebypass, postbypass, and intensive care unit (ICU) periods. Only 28% of TEE episodes (RWMA suggestive of ischemia) were preceded by acute changes in any hemodynamic parameter. Specifically, 7% of TEE episodes were preceded by increases in HR (20% deviation from control), 14% by increases in systolic blood pressure (SBP), 13% by decreases in diastolic blood pressure (DBP), and 9% by increases in pulmonary artery diastolic pressure (PAD). Twelve per cent of TEE episodes were associated with increases in rate-pressure product (RPP) to > 12,000, and 27% were associated with decreases in mean arterial pressure (MAP)/HR to < 1 at the onset of TEE episodes. Comparison among periods revealed that post-bypass TEE episodes were more frequently associated with either increases in demand or decreases in supply than were prebypass episodes (53% vs. 25%, P < 0.05). ECG ischemic episodes also were infrequently (30%) associated with acute changes in HR, SBP, DBP, or PAD. We conclude that perioperative TEE episodes are infrequently triggered by changes in hemodynamics, suggesting that a primary decrease in myocardial oxygen supply may be an important mechanism for most perioperative RWMA. In addition, neither pulmonary artery catheter pressure measurements nor specialized indices (RPP and MAP/HR) appear to be useful in predicting TEE episodes.