RV Electrical Activation in Heart Failure During Right, Left, and Biventricular Pacing

Abstract

Objective Compare right ventricular (RV) activation during intrinsic conduction to pacing in heart failure (HF) patients. Background Right ventricular (RV) activation during intrinsic conduction or pacing in patients with LV dysfunction (HF) is unclear but may affect prognosis. In cardiac resynchronization therapy (CRT), timed LV pacing (CRT-LV) may be superior to biventricular pacing (CRT-BiV), hypothesized to be due to merging of LV paced and right bundle branch (RBB) mediated wavefronts thus avoiding perturbation of RV electrical activation. We tested this. Methods Epicardial RV activation duration (RVAD: onset to end of free wall activation) was evaluated non-invasively by electrocardiographic imaging (ECGI) in normals (n=7) and compared to HF patients (LVEF 23±10%, n=14). RVAD in HF was contrasted during RV, CRT-BiV, and CRT-LV pacing at optimized AV intervals. Results During intrinsic conduction in HF (n=12), durations of QRS and precordial lead rS complexes were 158±24 and 77±17 ms respectively, indicating delayed total ventricular depolarization but rapid initial myocardial activation. Echocardiography demonstrated no significant RV disease. RV epicardial voltage, activation patterns and RVAD in HF did not differ from normal (RVAD 32±15 vs 28±3 ms respectively, p=0.42). In HF, RV pacing generated variable areas of slow conduction and prolonged RVAD (78±33 ms, p<0.001). RVAD remained delayed during CRT-BiV at optimized atrioventricular intervals (76±32 ms, p=0.87). In contrast, CRT-LV reduced RVAD to 40±26 ms (p<0.016) comparable to intrinsic conduction (P=0.39) but not when atrioventricular conduction was poor or absent. Conclusion In HF patients without RV dysfunction treated with CRT, normal RV free wall activation in intrinsic rhythm indicated normal RBB-mediated depolarization. However, the RV was vulnerable to developing activation delays during RV pacing whether alone or with biventricular CRT. These were avoided by CRT-LV in patients with normal atrioventricular conduction.

Real‐world behavior of CRT pacing using the AdaptivCRT algorithm on patient outcomes: Effect on mortality and atrial fibrillation incidence

“…This more physiological activation may also reduce RV pacing‐induced dyssynchrony. Previous small analyses have supported the benefits of LV pacing compared with RV pacing and BiV pacing in reducing RV activation times, improving RV dP / dt max , and RV stroke volume 22,23 …”

The right ventricle in patients with chronic heart failure and atrial fibrillation

“…Right ventricular pacing and heart failure RV pacing creates specific clinical conditions that affect RV function and may induce AF and CHF [47,48]. As a non-physiological mode of pacing it causes a loss of atrio-ventricular systolic synchrony.…”

Noninvasive Mapping of Electrical Dyssynchrony in Heart Failure and Cardiac Resynchronization Therapy

“…Right ventricular pacing (either alone or in conjunction with simultaneous biventricular pacing) in patients with heart failure with LBBB significantly altered RV (and LV) activation compared with intrinsic conduction via the RBB, 10,22 delaying RV activation and perturbing natural centrifugal spread of activation (see Fig. 3B; Fig.…”

“…As a result, RV total activation time is prolonged during RVAP. 22 Note that LV activation also changes. AP, anteroposterior; LAO, left anterior oblique; PL, posterolateral.…”