120: Effects of spinal anaesthesia on left ventricular function assessed by two-dimensional echocardiography

Abstract

Spinal anaesthesia (SA) is one of the most frequently realized techniques of regional anaesthesia to allow lower limbs surgery. Hypotension is an adverse effect commonly observed, especially in elderly patients. Indeed the sympathetic block induced by SA decreases left ventricular (LV) preload and afterload, the cardiac effect of SA is still controversial. The aim of this study was to compare the effect of SA and general anesthesia (GA) on left ventricular systolic function assessed by 2D strain by transthoracic echocardiography (TTE). During 6 months, 22 patients over 60 years old referred for elective lower limb surgery underwent TTE immediately before and 15 minutes after SA (n= 10) or GA (n= 12). Hypotension was more frequent in the GA group than in the SA group (83% vs. 16%, P =0.008). The use of fluid expansion and vasopressors was higher in the GA group (P =0.03). GA and SA induced both a significative increase of global longitudinal strain rate (−0.2 ±0.3%.s-1 vs. −0.2 ±0.3%.s-1 respectively; P [GA vs. SA]= ns). LV ejection fraction and LV telediastolic volume were not modified by both anesthesia. Systolic peak velocities at the mitral annulus by tissue Doppler imaging was increased by SA but not by GA (respectively +1.2 cm. s-1; P= 0.026 vs. −0.4 cm. s-1; P= 0.5). Diastolic function was modified by GA (E/A ratio = 1.1 ±0.3 vs. 1.2 ±0.4; P= 0.05) but not by SA (E/A ratio= 0.9 ±0.3 vs. 0.9 ±0.4; P= 0.24). All these effects lead to a decrease of aortic velocity time integral in the GA group contrary to in the SA group (−1.1 ±7.4 P= 0.02 for GA vs. −0.38 ±3.85, P= 0.8 for SA). Both SA and GA induce increase of LV global longitudinal strain rate and systolic peak velocity. During GA, these adaptations of systolic function are not enough to compensate the fall of systemic vascular resistance and lead to more hypotension than during SA. These results encourage privileging SA in patients without myocardial reserve, especially older patients.