Networked multielectrode left ventricular pacing lead for avoidance of phrenic nerve stimulation in a canine model

Abstract

In cardiac resynchronization therapy, left ventricular stimulation may lead to concomitant phrenic nerve stimulation (PNS). To evaluate a new networked multielectrode lead with 16 electrode segments (SEGs) configured into groups of 4, forming a virtual band (VBAND) around the lead. Each electrode is individually programmable using an embedded integrated circuit. In 8 anesthetized dogs, the lead was positioned in a left ventricular coronary vein. The voltage thresholds for cardiac stimulation and PNS were measured for different electrode configurations, including "VBAND-VBAND" (∼conventional bipolar pacing), "SEG-VBAND", and "SEG-SEG" (anode and cathode within the same VBAND). The measurements were performed (1) with closed chest and (2) after opening the chest and repositioning the phrenic nerve to above the lead, simulating a worst-case scenario. Compared with the conventional VBAND-VBAND stimulation, the SEG-SEG stimulation increased the PNS threshold and raised the difference between phrenic and cardiac thresholds from 6.2 ± 2.3 to 9.5 ±0.3 V in the closed chest condition and from 1.4 ± 1.6 to 9.0 ± 1.0 V in the worst-case scenario (both P < .001). Both SEG-VBAND and SEG-SEG stimulations reduced the cardiac threshold and increased pacing impedance, thus reducing the required cardiac pacing power by 77%-80% (P <.001 and P <.01 for closed and open chest, respectively). This novel multielectrode pacing lead achieves low cardiac and high extracardiac stimulation thresholds during left ventricular pacing in a canine model. The virtual elimination of PNS may facilitate and improve the application of cardiac resynchronization therapy.