Programmable multiple pacing configurations help to overcome high left ventricular pacing thresholds and avoid phrenic nerve stimulation.

BACKGROUND

High left ventricular pacing (LVP) thresholds and phrenic nerve stimulation (PNS) are common problems with cardiac resynchronization (CRT). Newer systems capable of multiple LVP configurations may help overcome these problems without the need for reoperation.

METHODS

CRT systems capable of multiple LVP configurations (Guidant models H155 and H145) were implanted in 43 patients (study group). An additional 49 patients (control group) received CRT systems (Guidant, Medtronic, Biotronik, St. Jude Medical, various models) lacking this feature.

RESULTS

Overall, acute high (> or =2.5 V/0.5 ms) LVP thresholds were encountered in 13 (30%) of the study group, and 25 (50%) of control group patients (P = 0.03). PNS was encountered in 5 (12%) of the study group and 12 (24%) of control group patients (P = 0.13). All cases of high LVP thresholds and PNS in the study group were managed by switching to a different LVP configuration, while high thresholds remained in control group patients, and PNS was managed by replacing the lead. The CS lead was successfully placed in a lateral branch in 95% of study group, compared to only 77% of control group patients (P = 0.004).

CONCLUSIONS

Multiple LVP configurations were clinically useful in a significant number of patients undergoing CRT system implantation by helping to overcome high LVP thresholds and PNS, and by providing more flexibility in placing the LV lead.