Dual-Chamber Leadless Pacing: Atrioventricular Synchrony in Preclinical Models of Normal or Blocked Atrioventricular Conduction

BACKGROUND

Dual-chamber leadless pacemakers (LP) require robust communication between distinct right atrial (RA) and right ventricular (RV) LPs to achieve atrioventricular (AV) synchrony.

OBJECTIVE

This preclinical study evaluated a novel, continuous implant-to-implant (i2i™) communication methodology for maintaining AV-synchronous, dual-chamber DDD(R) pacing by the 2 LPs.

METHODS

RA and RV LPs were implanted and paired in 7 ovine subjects, 4 of 7 with induced complete heart block. AV synchrony (% AV intervals <300 ms) and i2i communication success (% successful i2i transmissions between LPs) were evaluated acutely and chronically. During acute testing, 12-lead ECG and LP diagnostic data were collected from 5-minute recordings, in 4 postures and 2 rhythms (AP-VP and AS-VP or AP-VS and AS-VS) per subject. Chronic i2i performance was evaluated through 23 weeks post-implant (final i2i evaluation period: week 16-23).

RESULTS

Acute AV synchrony and i2i communication success across multiple postures and rhythms were 100.0% [100.0-100.0] (median [interquartile range]) and 99.9% [99.9-99.9], respectively. AV synchrony and i2i success rates did not differ across postures (P=0.59, P=0.11) or rhythms (P=1.00, P=0.82). During the final i2i evaluation period, the overall i2i success was 98.9% [98.1-99.0].

CONCLUSION

Successful AV-synchronous, dual-chamber DDD(R) leadless pacing using a novel, continuous, wireless communication modality was demonstrated across variations in posture and rhythm in a preclinical model.

Effectiveness of Ventricular Intrinsic Preference (VIP™) and Ventricular AutoCapture (VAC) algorithms in pacemaker patients: Results of the validate study

BACKGROUND

Several past clinical studies have demonstrated that frequent and unnecessary right ventricular pacing in patients with sick sinus syndrome and compromised atrio-ventricular conduction (AVC) produces long-term adverse effects. The safety and efficacy of two pacemaker algorithms, Ventricular Intrinsic Preference™ (VIP) and Ventricular AutoCapture (VAC), were evaluated in a multi-center study in pacemaker patients.

METHODS

We evaluated 80 patients across 10 centers in India. Patients were enrolled within 15 days of dual chamber pacemaker (DDDR) implantation, and within 45 days thereafter were classified to either a compromised AVC (cAVC) arm or an intact AVC (iAVC) arm based on intrinsic paced/sensed (AV/PV) delays. In each arm, patients were then randomized (1:1) into the following groups: VIP OFF and VAC OFF (Control group; CG), or VIP ON and VAC ON (Treatment Group; TG). Subsequently, the AV/PV delays in the CG groups were mandatorily programmed at 180/150 ms, and to up to 350 ms in the TG groups. The percentage of right ventricular pacing (%RVp) evaluated at 12-month post-implantation follow-ups were compared between the two groups in each arm. Additionally, in-clinic time required for collecting device data was compared between patients programmed with the automated AutoCapture algorithm activated (VAC ON) vs. the manually programmed method (VAC OFF).

RESULTS

Patients randomized to the TG with the VIP algorithm activated exhibited a significantly lower %RVp at 12 months than those in the CG in both the cAVC arm (39±41% vs. 97±3%; p=0.0004) and the iAVC arm (15±25% vs. 68±39%; p=0.0067). In-clinic time required to collect device data was less in patients with the VAC algorithm activated. No device-related adverse events were reported during the year-long study period.

CONCLUSIONS

In our study cohort, the use of the VIP algorithm significantly reduced the %RVp, while the VAC algorithm reduced in-clinic time needed to collect device data.