Permanent direct his bundle pacing doesn't induce ventricular dyssynchrony as opposed to conventional right ventricular apical ddd pacing

Abstract

Beneficial effects of A-V synchrony due to DDD right ventricular apical (RVA) pacing could be neutralized by ventricular dyssynchrony(D).No data are reported about effects of direct his bundle pacing(DHP) on ventricular synchronism. Aim To assess the capability of DHP to prevent pacinginduced ventricular D as compared to DDD-RVA pacing in pts undergoing permanent DHP. Methods 7 pts(2women,mean age 77+/−5)with normal HV were implanted for SSS(6 brady-tachy,1 LW II AVB) with a right atrium lead connected to the atrial channel of the device and a 4.1F screw-in hisian lead(Medtronic,Select Secure)connected to the ventricular channel.Two 4-polar leads through a femoral vein were used for DDD-RVA pacing. Fixation of permanent DHP lead was performed above the tricuspid valve using pacemapping and HB potentials. All pts underwent PW tissue Doppler imaging(TDI)analysis to assess inter- and intra-ventricular D. Interventricular mechanical delay(IVMD) between pulmonary and aortic systolic flow, septal to left posterior wall motion delay(SPWMD),and maximal difference between DTI systolic velocities of any 2 of the 4 left ventricle basal segments(maxmin DTI)were measured. DDD-RVA pacing was compared to DHP and to DHP+/−capture of right ventricular high inflow septum(RVHS)at the same atrial pacing rate after optimizing A-V interval. Results Permanent DHP was safely obtained in 6 of 7 pts (only RVHS pacing in 1 pt). DHP and RVHS pacing thresholds, impedance and sensed potentials of DHP leads were 1.4+/−0.65 V and 1.7+/−0.8 V(x0.5 ms),611+/−162 ohm and 5.7+/−3.7mV respectively.In 5 of 6 pts DHP threshold was slightly inferior to RVHS capture threshold.Procedural and fluoroscopy times were 145 min (range 106-147) and 10.3+/−4.4 min respectively. Inter- and intra-ventricular D were reduced during DHP in comparison with DDD-RVA pacing: IVMD 198+/−36 ms vs 47+/−39 ms(cut-off value: 110; p<0.05); V-VD 45+/−18 vs 3+/−2.12 (cut-off value:30;p<0.05);max-min DTI 33.3+/−5.77 vs 19.2+/−12.5(cut-off value:10 ms).Similar data were obtained comparing DHP+RVHS and DDD-RVA pacing.No differences were observed between DHP and DHP+RVHS pacing. Conclusion DHP is feasible and safe. It prevents pacing-induced ventricular D as opposed to standard RVA DDD pacing. Longer follow-up is required to assess left ventricle remodelling prevention.