Noninvasive assessment of left ventricular pressure-area relationship using transesophageal echocardiography and tonometry during cardiac and abdominal aortic surgery

Purpose: The purpose of this study was to noninvasively evaluate intraoperative left ventricular (LV) performance by an online pressure-area relationship using transesophageal echocardiography (TEE) and tonometry. Methods: In study 1, LV pressure with a micromanometer catheter, LV cross-sectional area with TEE, direct radial pressure, and tonometric arterial pressure were simultaneously recorded in 5 patients (10 measurements) undergoing cardiac surgery. End-systolic elastance (E′es) was determined from pressure-area loops during inferior vena caval (IVC) occlusion. In study 2, in 16 patients undergoing repair of abdominal aortic aneurysm, LV performance (E′es; effective arterial load, E′a, and LV end-diastolic area, LV-EDA) was examined by noninvasive assessment of pressure-area loops using TEE and tonometry at aortic cross-clamping and unclamping. Results: E′es by tonometric arterial pressure closely correlated with E′es by LV pressure (r = 0.92) in study 1. E′es at aortic clamping were not significantly different from those at unclamping. The clamping increased LV-EDA and E′a by approximately 13% and 44%, and the unclamping significantly decreased by 9% and 22%, respectively. Conclusion: Our results demonstrated that online tonometric arterial pressure and LV area measured by automated border detection (ABD) of TEE might be used to calculate E′es to estimate LV contractility and allow the estimation of LV performance during aortic clamping and unclamping.