Background: His bundle pacing (HBP) results in rapid synchronous ventricular activation, but has been associated with long procedure times and compromised pacing and sensing performance. This study sought to reduce procedure time and radiation exposure, and improve electrical performance through more accurate lead placement.
Methods: Intracardiac echocardiography (ICE) was used to guide ablation and lead implantation at the His bundle, right atrial appendage (RAA), and right ventricular apex (RVA), and to assess cardiac function. Custom bipolar screw-in leads with steerable delivery sheaths and an ablation catheter were navigated using ICE (local detailed imaging) and fluoroscopy (global imaging) in anesthetized closed-chest canines (N = 6).
Results: HBP (N = 1) or His + ventricular septal pacing (N = 5) was achieved in all canines. The QRS width was 59.7 +/- 5.3 ms for canines in sinus rhythm (SR) and 82.8 +/- 16.6 ms for canines with HBP (P = 0.0086). The QRS width for RVA pacing was 106.3 +/- 18.4 ms (P = 0.042 vs HBP; P = 0.00013 vs SR). HBP thresholds were 3.0 +/- 1.0 volts at 0.5 ms (N = 5 due to a late exit block in one canine). The average procedure duration for His lead placement was 40 +/- 28 minutes (range of 3-81 minutes) and the total procedural X-ray exposure was 12 +/- 12 minutes (range of 2-30 minutes). Hemodynamic performance was similar for HBP and RAA pacing.
Conclusions: Feasibility of ICE guidance for His pacing and precision ablation of the atrioventricular (AV) node has been shown. This anatomic approach improved accuracy, limited X-ray exposure, and might allow His pacing in patients with preexisting AV nodal block.