Case Report: Impact of Recommended Replacement Time Pacing Behavior in a Pacemaker Programmed to Atrial Antibradycardia Pacing Mode Secondary to Known Ventricular Lead Failure
Recommended replacement time (RRT) and elective replacement time (ERI) pacing behaviors are foundational knowledge for experienced device specialists. However, in settings of highly specialized or individualized device programming, critical and analytical assessment skills must be employed to recognize RRT impact.
This case report explores a recent PaceMate remote cardiac implantable electronic device (CIED) transmission received from a patient with a dual-chamber pacemaker implanted on September 23, 2010.
Background
A remote CIED transmission was received by PaceMate on June 9, 2022, and was noted to have urgent alerts for the battery reaching RRT and for a right ventricular (RV) lead impedance above upper limits.
A look back at the previous CIED transmission revealed that the device was nearing RRT. The frequency of remote monitoring was increased by the PaceMate team from quarterly to monthly to monitor the battery status of the device more closely.
Case Presentation
The initial transmission review demonstrated that the pacemaker triggered RRT on June 9, 2022, with a battery voltage of 2.58V and a battery impedance of 8715 ohms. It was noted that the device was pacing in RRT mode of ventricular pacing (VVI) at 65 bpm, which is the normal and expected standard for the device model with a programmed pacing amplitude of 0.5V at 1.0 ms. The presenting RV lead impedance was 4992 ohms with no reported ventricular pacing threshold or ventricular sensing measurements available for this transmission review.
Upon further assessment, the non-magnet electrogram (EGM), which was limited to channel markers only, was found to have ventricular pacing with intrinsic breakthrough suggestive of ventricular non-capture. A review of the long-term pacing and impedance lead trends revealed normal atrial lead measurements, a chronically elevated RV pacing threshold of 6V at 1.0 ms, as well as a chronically elevated RV lead impedance with a previous maximum upper range of 3415 ohms.
The subsequent review of the most recent transmission prior to the June 9th transmission revealed that the device was previously programmed in atrial antibradycardia pacing (AAIR) mode and had a battery longevity estimation of 10 months with a minimum of <1 month and a maximum of 20 months.
Discussion
This patient had a known history of a malfunctioning RV lead with normal atrioventricular conduction and had been successfully managed in AAIR mode for quite some time. Their device is an older model, and consistent with many older pacemaker models, the RRT mode of VVI at 65 bpm is automatic and permanent upon triggering RRT.
Also of note, once RRT is triggered, the pacing amplitude will automatically revert to the most recent prior programmed output, which in this case was 0.5V at 1.0 ms, and which would have most likely been subthreshold even if the RV lead had been functioning properly.
It should also be noted that although the pacing mode of VVI is permanent, the pacing amplitude is programmable upon RRT if adjustments are required. In this case, mode switching from AAIR to VVI with a very low programmed pacing amplitude essentially left the patient without pacing support due to a malfunctioning RV lead.
After prompt review of the transmission by the device clinic technicians, an immediate call was placed to the patient’s provider to advise of the RRT status of the battery and the loss of pacing support. The provider immediately contacted the patient. It was reported that the patient was aware that his heart rate was in the 40s but did not report symptoms. The patient was promptly scheduled for a pacemaker generator change, which was performed on June 17, 2022.
The average estimated battery life of a pacemaker is 8-10 years. Battery longevity can precipitously deplete as it nears RRT. In older model pacemakers such as this one, the expected battery depletion range will be as follows: 90% of batteries will deplete within the estimated range, 5% will deplete at the minimum estimated range, and 5% will deplete at the maximum estimated range.
It is crucial to consider the minimum estimated battery estimation, especially for dependent patients or patients with known lead complications, such as the patient in this scenario. It is also important to take into consideration current programming and lead function to ascertain if the RRT mode of VVI is a safe option for the patient. If the RRT mode of VVI is not a safe option for the patient, serious consideration to early generator change should be given to mitigate patient safety issues triggered by RRT.
Conclusion
It cannot be emphasized enough that when a device is nearing RRT, intensified follow-up is recommended. Knowledge of device RRT functionality, with consideration of individual patient needs, is paramount for patient safety. Although the AAIR pacing mode is uncommon, the RRT mode switch to VVI should always be assessed for patient safety in devices that are nearing RRT.
Intensified monthly remote follow-up, initiated by the PaceMate team, as well as prompt review and assessment by the device clinic technicians, enabled this potentially dangerous scenario to be identified and reported to the physician within minutes of transmission receipt. The ability to quickly review urgent alerts on a 24-hour basis, and the clinical expertise to identify and react with timely intervention, is critical for efficient device management and patient safety.
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This article is published with support from PaceMate™.
