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) incorporating 4 electrodes arranged at the lead-tip, organized in an equidistant tetrahedron. Here, we studied Max 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 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. Sensing via Max positioned at RV apex was tested during sinus rhythm (SR), pacing from RV and left-ventricular (LV) free-wall, and ventricular fibrillation (VF). Max-enabled voltage (Max), defined as the largest span of the sensed electric field loop, was compared with traditional lead-tip voltage detection.

RESULTS

Pacing: Max 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 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 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.