Wireless pacemakers may be safe for children

Wireless or leadless pacemakers, commonly implanted in adults, may be a safe and effective short-term option for children with slow heartbeats, according to a new study published in the journal Circulation: Arrhythmia and Electrophysiology.

Children with a heartbeat that is too slow (bradycardia) require pacemakers — devices surgically implanted under the skin of the chest that transmit electrical impulses to regulate the heartbeat. Standard pacemakers use tiny wires, or leads, that are connected to the heart to deliver the lifesaving pacing (electrical signals to keep the heart beating normally). Active, growing children, however, are at higher risk for wire fractures and pacemaker complications because the wires in typical pacemakers may break or malfunction.

The leadless pacemaker is a miniature device, the size of a AAA battery, that is self-contained and placed directly inside the patient’s heart, so it does not require leads to help regulate the heartbeat. The new study provides the first known data on leadless pacemakers in a paediatric population in a real-world setting.

The Pediatric and Congenital Electrophysiology Society (PACES) maintains a registry of pacemaker implantations performed at 15 centres across the US, the UK and Italy. During the study period (2016–2021), cardiac electrophysiologists implanted the leadless device in carefully selected patients who were experiencing a slow heartbeat. Researchers evaluated data in the registry for Medtronic’s Micra brand of leadless pacemakers to analyse how well the leadless pacemaker performed in 63 children, ages 4 to 21 years (average age 15). For 77% of these children, this was their first pacemaker.

The analysis found that 62 of the 63 children had the leadless pacemaker successfully implanted, and the heart’s electrical parameters were stable within the first 24 hours. During an average follow-up period of about 10 months, the pacemaker was effective in its overall performance, including battery longevity, low pacing threshold (signals if pacemaker is performing well) and ability to detect the heart’s native electrical beats.

Overall, 16% of the children experienced complications after receiving the leadless pacemaker. Most of these were due to minor bleeding, which was treated promptly and easily. There were three major complications — one blood clot in the femoral vein of one patient, one cardiac perforation and one patient had suboptimal pacemaker function requiring removal of the pacemaker after one month.

“Using adult catheter-guided delivery systems in children is challenging and may increase the risk of major complications,” noted lead author Maully J Shah, a professor of paediatrics at the University of Pennsylvania. “Since these are big catheters, selection of patients by size is very important. Two out of the three complications occurred in patients weighing less than 60 pounds.

“The femoral vein in the groin is the conventional route to place the leadless pacemaker. For some patients, especially the younger and smaller children, the jugular vein (in the neck) was a better option because it provides a more direct route to implant the tiny pacemaker in a smaller heart.”

During the follow-up period after implantation, the leadless pacemakers continued to have stable performance, and there were no reported complications. The researchers have now converted this retrospective study to a prospective study and plan to follow the patients for an additional five years.

“Our study’s results indicate select children may be considered candidates since they may benefit greatly from leadless pacing,” Shah said. “However, because of the current technology, which uses a very large catheter designed for adults to place the leadless pacemaker and lack of reliable future extractability of the pacemaker, the wider paediatric population is not able to benefit from this device.

“Techniques and tools to place the device must be designed for smaller patients, specifically children, and there needs to be a mechanism to remove and replace this pacemaker without surgery when the battery runs out since paediatric patients will likely require pacing for the rest of their lives, which is several decades after implantation.”

Image caption: The Medtronic Micra transcatheter pacemaker was utilised in the study. Image ©Medtronic.