A Display of Combined Left Ventricular Function and Dyssynchrony Using Doppler Tissue Imaging: Its Application in Acute Response to Cardiac Resynchronization Therapy

Abstract

We have recently proposed a novel method for displaying left ventricular (LV) function and mechanical dyssynchrony, which is based on the "vector analysis" using Doppler tissue imaging (DTI). The aim of this study was to examine acute-phase impact of cardiac resynchronization therapy (CRT) on the parameters assessed by this method. We studied a total of 25 patients with systolic heart failure, 14 undergoing simultaneous acute pacing-hemodynamic study and DTI; and 11 patients DTI within a few days before and one week after CRT. Parameters derived from the displaying method were followings: (1) percentage area of the hexagon, the area divided by the overall graph area, reflecting global LV systolic function; (2) net-delay magnitude, the length of the composite vector for the six vectors, a dyssynchrony index; and (3) delayed contraction site, graphical position of the composite vector. CRT significantly increased cardiac output (3.1 ± 1.0 to 3.4 ± 0.7 L/min, P = 0.02) and +dp/dt (782 ± 149 to 1,089 ± 270 mm Hg/s, P < 0.01), and decreased mitral regurgitaion jet area (7.9 ± 3.0 to 4.8 ± 2.4 cm(2) , P < 0.01). As with the new method, there were significant decreases in the percentage area of the hexagon (20.7 ± 6.6 to 18.6 ± 6.5%, P < 0.01) and the net-delay magnitude (122 ± 59 to 72 ± 48 ms, P < 0.01). The reduction of net-delay magnitude accompanied alteration of delayed contraction site; 16 patients had the most delayed site between the lateral and inferior segments before CRT, and seven patients after CRT (P = 0.02). The new method would be a useful tool to assess efficacy of CRT in patients with systolic heart failure.