Echocardiography Evaluation Of The Order Of The Dual-chamber Pacing In Patients With Ventricular Contraction Synchrony Research

Part 1 Evaluation of Intraventricular Systolic Dyssynchronyusing EchocardiographyObjective To evaluate the intraventricular systolic dyssynchrony in patients with left bundle branch block by tissue Doppler imaging (TDI) and standard echocardiography. Methods 20 subjects with isolated left bundle branch block (LBBB), and 20 normal controls were recruited in this study. TDI was performed using a 6-basal, 6-mid left ventricular (LV) segmental model to measure the time intervals from the beginning of the QRS complex to the peak systolic velocities (Ts). The coefficient of variation (SD/mean) of 12 different T_s were calculated and used as the index of systolic dyssynchrony (SDI). The myocardial performance index (MPI), LV ejection fraction (EF), and filling time (FT) were also measured. Results A significant difference was observed in the Ts (209 ±31ms versus 154 ±12ms, P<0.001) and SDI (17.2±4 versus 7.7±2.7, P<0.001) between LBBB and normal group, patients with LBBB had longer electromechanical delays. Compared with normal control, patients with LBBB had larger MPI, lower EF and shorter FT (all P<0.001). Conclusion In patients with LBBB, electromechanical delays were different in each segment that leads to generalize intraventricular dyssynchrony, thereby explaining the depressed global LV functions. Combined with the evaluation of global LV function, TDI may be better to assess the electromechanical uncoupling processes and intraventricular dyssynchrony. Part 2 Evaluation of Interventricular Systolic Dyssynchronyusing Echocardiography...