Little pacemakers ‘reliable’ in stabilizing newborns needing pacing
Key takeaways:
- Novel miniature pacemakers were safely implanted in neonates and infants requiring pacing.
- The pacemakers performed reliably for up to 2 years with no unexpected device failures.
Miniaturized pacemakers were successfully implanted in infants and neonates requiring pacing and performed reliably until planned explant and/or replacement with a standard-sized device, researchers reported.
Currently, standard pacemakers are too large for use in small neonates, and as a result, the complication rate can be as high as 25%, and include infection, erosion and migration of the device, according to study findings published in Circulation: Arrhythmia and Electrophysiology.
“The need for pacing in neonates and infants is rare, but when indicated, can sometimes be urgent, necessitating surgery in the first few days of life,” Charles I. Berul, MD, pediatric electrophysiologist at Children’s National Hospital, The Van Metre Companies Endowed Chair in Cardiology and professor of pediatrics and bioengineering at George Washington University School of Medicine, told Healio. “There are likely approximately 50 to 100 pacemakers placed in neonates due to congenital heart block annually. Additionally, some neonates and infants require permanent pacemakers following congenital heart surgery due to postoperative heart block.”
To address this unmet need, Berul and colleagues alongside Medtronic designed a modified pacemaker (Micra VR) featuring a polyetheretherketone (PEEK) polymer header connected to a standard bipolar epicardial lead. The device is approximately one-fifth the size of standard pacemakers and has been implanted in neonates for the past 2 years.
“The Micra is designed for transvenous use through a large sheath in the femoral vein,” Berul told Healio. “It was modified by Medtronic to be able to attach to a standard epicardial lead, allowing its use in infants.”
Modified pacemaker for use in neonates, infants
The present study included midterm follow-up data and outcomes among 29 patients who underwent implantation between March 2022 and February 2024 at 12 sites in the U.S.
The age of implanted patients ranged from 0 days to 3 years (median age, 15 days) and the median weight was 2.3 kg.
Overall, 79% of patients were born premature and approximately one-quarter had a congenital heart defect.
The most common indication for pacemaker implantation was congenital atrioventricular block, followed by postoperative atrioventricular block and sinus node dysfunction. One patient had second-degree atrioventricular block.
The mean duration of implantation was 325 days; the most recent average lead impedance was 612 ohms, mean ventricular capture threshold was 1 V at 0.4 milliseconds and average R-wave sensing was 12.5 mV, according to the study.
Battery longevity was in line with the projected estimate of 2.6 years, with 100% pacing at 120 bpm, 500 ohms and 2.5 V at 0.4 milliseconds in the average of most recent readings.
“We are very pleased with the results, showing reliable performance out to 2 years so far, and performing consistent with projected battery life, with no unexpected device failures,” Berul told Healio. “This current report describes the first 29 infants in U.S. to receive this pediatric pacemaker, and there are now approximately 60 implanted worldwide. We included these 29 who had sufficient follow-up after implant from 12 of the 15 implanting U.S. centers.”
Pacemaker explant and procedural complications
Twenty devices in the present analysis are still active and seven were explanted during the study period. Reasons for explant are as follows:
- one for a planned upgrade to a dual-chamber pacemaker;
- two for high capture thresholds leading to battery replacement;
- two for high thresholds and increasing lead impedances with loss of capture, possibly due to lead pin placement;
- one for wound dehiscence and pocket infection at age 2 years; and
- one for normal battery depletion at age 20 months.
None of the pacemakers were replaced with the new pediatric device, as the patients had grown enough for a standard pacemaker, according to the study.
There were two patient deaths, both reported to be unrelated to the pacemaker or implant procedure.
Procedural complications included that one premature neonate underwent pocket revision 3 days after implant due to concerns for skin erosion; one patient had a late large pericardial effusion after 19 days; and another one had recurrent wound dehiscence and pocket infection 2 months after implant, possibly due to fungal seeding from prior epigastric surgery. The researchers reported no other complications attributable to the pediatric pacemaker.
“Future goals are to modify further to allow percutaneous approach rather than requiring the cardiac surgeon to open the chest to place the lead on outside of heart,” Berul told Healio. “We have performed this successfully on benchtop simulator and in preclinical models but not yet in humans.”
For more information:
Charles I. Berul, MD, can be reached at 111 Michigan Ave. NW, Washington, D.C. 20010.
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