Multi-Axes Lead With Tetrahedral Electrode Tip for Cardiac-Implantable Devices: Creative Concept for Pacing and Sensing Technology

Abstract

Background: We developed a multi-axes lead (Max_Lead) incorporating 4 electrodes arranged at the lead-tip, organized in an equidistant tetrahedron. Here, we studied Max_Lead performance in sensing, pacing, and activation wavefront-direction analysis.

Methods: Sixteen explanted animal hearts (from 7 pigs, 7 sheep, and 2 rabbits) were used. Pacing threshold was tested from all axes of Max_Lead from right-ventricular (RV) apex before and after simulated dislodgement. In addition, conduction-system pacing was performed in sheep heart preparations from all axes of Max_Lead. Sensing via Max_Lead positioned at RV apex was tested during sinus rhythm (SR), pacing from RV and left-ventricular (LV) free-wall, and ventricular fibrillation (VF). Max_Lead-enabled voltage (Max^V), defined as the largest span of the sensed electric field loop, was compared with traditional lead-tip voltage detection.

Results: Pacing: Max_Lead minimized change in pacing threshold owing to lead dislodgement (average voltage change 0.2 mV; 95% confidence interval [CI], -0.5 to 0.9), using multiple bipoles available for pacing. In animals with high conduction system-pacing thresholds (> 2 mV) in 1 or more bipoles (3 of 7), acceptable thresholds (< 1 mV) were demonstrated in an average of 2.5 remaining bipoles. Sensing: Max^V of SR and VF was consistently higher than the highest bipolar voltage (voltage difference averaged -0.18 mV, 95% CI, -0.28 to -0.07), P = 0.001). Electric field-loop geometry consistently differentiated ventricular activation in SR from that during pacing from RV and LV free walls.

Conclusions: The multi-axes Max_Lead electrode showed advantages in pacing, sensing, and mapping and has the potential to allow for improvements in lead-electrode technology for cardiac-implanted electronic devices.