25 Determining optimal dual chamber algorithm to favor spontaneous AV conduction: preliminary results of the Saver study

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 effect of direct his bundle pacing (DHP) on ventricular synchronism. Aim: To assess the capability of DHP to prevent pacing-induced ventricular D as compared to DDD-RVA pacing in pts undergoing permanent DHR Methods: 7 pts (2women, mean age 77-t-5) with normal HV were implanted for SSS (6 brady-tachy, 1 LW II AVB) with a fight atrium lead connected to the atrial channel of the device and a 4.1F screwin hisian lead (Medtronic, Select Secure) connected to the ventricular channel. Two 4-polar leads through a femoral vein were used to perform DDD-RVA pacing. Fixation of permanent DHP lead was performed above (6) or under (1) the tricuspid valve using multiple oblique views, pacemapping and HB potentials. All pts underwent echo and PW tissue Doppler imaging (TDI) analysis to assess the 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 (max-min DTI) were measured. DDD-RVA pacing was compared to DHP and to DHP +/-capture of fight 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). Hisian and ventricular (RVHS) pacing thresholds, impedance and sensed potentials of hisian leads were 1.44-0.65 V and 1.74-0.8 V (x0.5 ms), 6114-162 ohm and 5.74-3.7mV respectively. In 5 of 6 pts hisian pacing threshold was slightly inferior to RVHS threshold of capture. Mean procedural and fluoroscopy times were 145 min (range 106-147) and 10.34-4.4 min respectively. Echocardiographic indexes of inter-and intra-ventricular D were reduced during DHP in comparison with DDD-RVA pacing: IVMD 1984-36 ms vs 474-39 ms (cut-offvalue: 110; p<0.05); V-VD 454-18 vs 34-2.12 (cut-off value: 30;p<0.05); max-min DTI 33.34-5.77 vs 19.24-12.5 (cut-off value: 10 ms). Similar differences were obtained comparing DHP + RVHS and DDD-RVA pacing modalities. Moreover no significant differences were observed between DHP and DHP + RVHS pacing. Conclusion: DHP is feasible and safe with relatively low radiological exposure.It prevents pacing-induced ventricular D as opposed to conventional RVA DDD pacing. Long-term follow-up is necessary to assess the stability of this modality of permanent cardiac pacing and its prevention of left ventricle remodeling. Different dual-chamber pacing modes are nowadays available to pace Sinus Node Dysfunction (SND) patients (pts.) to avoid unnecessary ventricular pacing (Vp). The objectives of this study were to assess the respective efficacy of different pacing modes. Methods: the AAIsafeR2 mode behaves like an AAI mode until one of different predefined patterns of atrio-ventricular blocks (AVB) or ventricular pause occur and ...