ASSESSMENT OF CHANGES IN LEFT-VENTRICULAR WALL STRESS FROM THE END-SYSTOLIC PRESSURE-AREA PRODUCT

We have measured the left ventricular (LV) end-systolic (ES) pressure- area product in 30 patients under general anaesthesia. We multiplied s ystolic arterial pressure with the ES cavity area obtained by transoes ophageal echocardiography, and compared the product with M-mode derive d ES wall stress before and during cardiovascular treatment. To attain appropriate mean arterial pressure during major non-cardiac surgery, 10 hypertensive patients required treatment with nitroglycerin, 10 sep tic patients received noradrenaline and 10 patients with intraoperativ e cardiac failure were given adrenaline. Baseline values and relative changes in the ES pressure-area product correlated well (r = 0.85 and r = 0.87; P < 0.05) with those of ES wall stress. Changes in the ES pr essure-area product by more than 10% reflected ES wall stress changes with a sensitivity of 88% and a specificity of 94%. With adrenaline, t he ES pressure-area product and ES wall stress did not change signific antly, while systemic vascular resistance increased by 20%. The ES pre ssure-area product seems suitable for the detection of intraoperative LV wall stress changes.