What Are the Clinical Benefits of Bifentricular Pacing in Heart Failure Patients?

摘要

The conventional DDD mode of pacing, using the right ventricular (RV) apex as the usual site of depolarization, results in retrograde activation of the left ventricle (LV). This opposite electrical sequence produces deleterious hemodynam-ic effects as well as the left bundle branch block regularly associated with dilated cardiomyopathy [1]. Optimization of the atrioventricular delay (AVD) provides a better LV filling pattern but does not always compensate RV pacing consequences [2]. Biventricular (BV) pacing was therefore developed to prevent interventricular dyssynchrony and, potentially, intraventricular dyssynchrony. BV pacing was initially demonstrated to provide acute hemodynamic improvement in patients with severe congestive heart failure (CHF) with prolonged QRS duration [3-5]. With BV pacing, the first clinical studies revealed an acute diminution of the capillary wedge pressure associated with an improvement in the cardiac index, suggesting regression of heart failure symptoms. However, potential clinical benefits were only confirmed at a mid-term follow-up.