What factors influence hemodynamic improvement after right ventricular to biventricular pacing system upgrade?

Abstract

It is still hard to predict hemodynamic effects after biventricular pacing system (BiVp) implantation despite established inclusion criteria for CRT and left ventricular pacing (LVp) techniques. The aim of the study was to find the predictors of acute hemodynamic improvement after right ventricular (RVp) to biventricular pacing system upgrade. Methods: The study group consisted of 69 patients with permanently implanted BiV pacing system with standard CRT criteria. Hemodynamic effect was determined using impedance cardiography (BioZ.com; Cardiodynamics). Cardiac Index (CI) and other indirect parameters were determined during 3 min periods of RV and BiV pacing in turn. Correlations were searched among clinical, echocardiographic, ECG and initial hemodynamic parameters and multivariate analysis was performed as well. Results: Cardiac contractility was higher during BiVp than RVp and LVp: CI (l/min/m2): RVp 2,29* LVp 2,20∧ BiVp 2,56*∧ [*∧ANOVA-LSD p>0,05]. Increase of CI after RV to BiV reprogramming correlated with CI during RVp (r=−0,50 p>0,001), Thoracic Fluid Index (TFI) (r=−0,32 p>0,01) and with difference of CI between RVp vs LVp (r=0,57 p>0,001) and LVp vs BiVp (r= 0,30 p>0,05). Values of CI during LVp, BiVp, echocardiographic parameters, NYHA class, RVp-, LVp-, BiVp- QRS durations and axis, and their changes did not correlated with differences of CI during RVp and BiVp. Multivariate analysis showed that only CI during RVp and RVp vs LVp CI difference determined acute hemodynamic effect of BiVp in comparison to RVp. Conclusions: Increase of CI after RVp to BiVp upgrade depends mainly on cardiac performance during right ventricular pacing and its improvement caused by change from RVp to single site LVp.