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

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.

Automated summary

The study found that Max(Lead) has advantages in minimizing pacing threshold changes due to lead dislodgement and in providing multiple bipoles for pacing. In sensing, Max(V) consistently outperformed traditional bipolar voltage detection, and the electric field-loop geometry was able to differentiate ventricular activation under different conditions.