Surgical Ventricular Restoration Improves Mechanical Intraventricular Dyssynchrony in Ischemic Cardiomyopathy

Abstract

Background— In ischemic cardiomyopathy, dyssynchrony of left ventricular (LV) mechanical contraction produces adverse hemodynamic consequences. This study tests the capacity of geometric rebuilding by surgical ventricular restoration (SVR) to restore a more synchronous contractile pattern after a mechanical, rather than electrical, intervention. Methods and Results— A prospective study of the global and regional components of dyssynchrony was conducted in 30 patients (58±8 years of age) undergoing SVR at the Cardiothoracic Center of Monaco. The protocol used simultaneous measurements of ventricular volumes and pressure to construct pressure/volume (P/V) and pressure/length (P/L) loops. Angiograms were done before and after SVR to study a 600-ms cycle during atrial pacing at 100 bpm. Mean QRS duration was similar, at 100±17 ms preoperatively and 114±28 ms postoperatively (NS). Preoperative LV contraction was highly asynchronous, because P/V loops showed abnormal isometric phases with a right shifting. Endocardial time motion was either early or delayed at the end-systolic phase so that P/L loops were markedly abnormal in size, shape, and orientation. Postoperatively, SVR resulted in leftward shifting of P/V loops and increased area; endocardial time motion and P/L loops almost normalized to allow a better contribution of single regions to global ejection. The hemodynamic consequences of SVR were improved ejection fraction (30±13% to 45±12%; P =0.001); reduced end-diastolic and end-systolic volume index (202±76 to 122±48 and 144±69 to 69±40 mL/m 2 ; P =0.001); more rapid peak filling rate (1.75±0.7 to 2.32±0.7 EDV/s; P =0.0001); peak ejection rate (1.7±0.7 to 2.6±0.9 Sv/s; P =0.0002), and mechanical efficiency (0.56±0.15 to 0.65±0.18; P =0.04). Conclusions— SVR produces a mechanical intraventricular resynchronization that improves LV performance.