Comparison of Different Pacing Strategies to Minimize Phrenic Nerve Stimulation in Cardiac Resynchronization Therapy

Abstract

Introduction Phrenic nerve (PN) stimulation (PNS) frequently limits cardiac resynchronization therapy (CRT). Yet, pacing strategies to minimize PNS have not been systematically compared. We propose to: 1) compare different pacing strategies to minimize PNS in CRT and 2) evaluate differences between PN and left ventricular (LV) capture thresholds among LV pacing configurations. Methods and Results PN and LV thresholds were obtained using 6 LV configurations in 28 patients with any PNS during CRT implantation or replacement. Incidence of PNS was compared in all LV configurations by programming pacing output to 1) One Volt above LV threshold, 2) triple pulse width (PW) at LV threshold, and 3) 1.5 times LV threshold for each patient. PN thresholds and PN strength-duration curves were statistically different between configurations (P<0.05). Ring→RVcoil and Ring→Can had the largest difference between PN and LV thresholds. Pacing output programmed to 1.5 times LV threshold, 1 Volt above LV threshold and triple PW at LV threshold had similar probability of PNS between LV configurations. However, 1 volt above LV threshold and triple PW at LV threshold frequently resulted in poor (<30%) LV capture safety margin (14–43% and 53–68%, respectively). Freedom from PNS (programmed output at twice LV threshold) was found in 88%, 84% and 52% with 6, 3, or 2 available LV configurations, respectively. Conclusion Multiple LV pacing configurations marginally increase the probability of avoiding PNS by electronic reprogramming. Pacing output programmed to 1.5 times LV threshold is an additional alternative to minimize PNS when electronic reprogramming options are limited.

Crossing of strength–duration curves with His bundle pacing and impact of pacing mode on thresholds

“…Differences in chronaxie between the phrenic nerve and ventricular myocardium have been exploited to avoid phrenic nerve capture at longer pulse widths for coronary sinus leads. 3 , 4 , 5 …”

“…Differences in chronaxie between the phrenic nerve and ventricular myocardium have been exploited to avoid phrenic nerve capture at longer pulse widths for coronary sinus leads. [3][4][5] Jastrzębski et al studied strength-duration curves for HBP in 127 patients and found lower chronaxie for the His bundle compared to local RV myocardium in patients with S-HBP (whereas chronaxie did not differ in patients with obligatory NS-HBP). 6 As a result, S-HBP is facilitated with pacing at shorter pulse width.…”

Percutaneous Epicardial Pacing Using a Novel Insulated Multi-Electrode Lead

“…With coronary sinus lead placement, phrenic stimulation affects approximately 15% to 30% of patients (14,15), requiring either repositioning the lead or electrically reprogramming another vector, both of which may result in lead dysfunction (16,17). Detecting phrenic stimulation at implantation has poor sensitivity due to positional dependency (18) calling for alternative strategies for preventing stimulation.…”

His bundle has a shorter chronaxie than does the adjacent ventricular myocardium: Implications for pacemaker programming

“…Another area where knowledge of strength-duration curves for the HB might play a role is the achievement of selective vs nonselective HB capture. A few studies reported that differences in chronaxie values enable selective pacing of different tissues from the same electrode by using a different combination of pulse widths and voltage output [12][13][14][15] ; whether this is also the case with HB/RV myocardium capture is not known.…”