Factors influencing differences of rva ; rvot pacing hemodynamic effects

Abstract

It was proved that right ventricular apex pacing (RVAp) deteriorates synchrony of ventricular contraction and decreases cardiac performance. Right ventricular outflow tract pacing (RVOTp) is more favorable pacing option due to better sequence of ventricular activation. The aim of the study was to compare acute hemodynamic effects of RVAp and RVOTp and to find the predictors of differences between those two modes. Methods In 51 patients, during implantation of pacing system, cardiac performance was evaluated at RVA and RVOT pacing modes by means of impedance cardiography (BioZ.com;Cardiodynamics). Indices of contractility: Acceleration Index (ACI), Velocity Index (VI) and Cardiac Index (CI) were determined as well as the LV ejection time (LVET) and pre-ejection period (PEP). The measurements in 3 min periods were collected and averaged, after the adaptation period of 5 min. Results In 65% of pts RVOTp showed to be more favourable than RVAp. The differences of CI after replacement of RVA to RVOTp were dependent on cardiac contractility during RVA pacing (CI: r=−0,48 p<0,001; PEP: r=0,27 p=0,052, LVET: r=−0,34 p=0,02; VI: r=−0,29 p=0,04) and echocardiographic parameters as LVEF (r=−0,36 p=0,02) and LVPWd (r=0,40 p=0,01). The differences did not correlated with RVA paced QRS duration and with change of axis deviation after RVAp to RVOTp change. Multivariate analysis showed that only CI during RVAp was the independent factor influencing RVAp-RVOTp differences of CI. Conclusions RVOT pacing provides significantly higher cardiac performance than standard RVA pacing. The acute positive effect of RVOT vs RVA pacing is more visible in insufficient hearts. RVOTp should be considered as an alternative for patients with impaired cardiac per performance (without current CRT indications).