A study of miniaturized, leadless pacemakers found that, due to their smaller size, they could provide a promising, short-term option for certain children with abnormally slow heartbeats.
These self-contained devices, embedded within the interior of the cardiac wall, may offer advantages over traditional pacemakers, which require wires threaded into the heart from a separately implanted generator—wires that can bend or break in the bodies of growing children.
However, the methods for placing these smaller implants are still designed for the larger anatomy of adults, the researchers said.
Additionally, though their batteries may last for five to 10 years, there still need to be more reliable ways to remove the implant from a younger patient at the end of the device’s lifetime, without resorting to open heart surgery, before the technology can be rolled out to a wider population.
“Using adult catheter-guided delivery systems in children is challenging and may increase the risk of major complications,” lead study author Maully Shah, director of cardiac electrophysiology at Children’s Hospital of Philadelphia, said in a release. “Since these are big catheters, selection of patients by size is very important.”
The researchers examined real-world registry data following Medtronic’s Micra wireless pacemaker, including from 63 children spanning ages 4 to 21, while 23% of patients had previously had a pacemaker. With an average age of 15, all but one had their leadless device successfully implanted. After about 10 months, the wireless implants showed they could effectively control and stabilize heart rhythms.
Ten children saw complications during or following implantation, mostly related to minor bleeding. Three, however, had major issues: one blood clot in the major vein of the thigh, a perforation of the muscle wall that leaked fluid into the area around the heart and one patient who needed their misplaced pacemaker removed after one month. There were no deaths in the study.
"Two out of the three complications occurred in patients weighing less than 60 pounds,” said Shah.
“The femoral vein in the groin is the conventional route to place the leadless pacemaker,” he said. “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.”
The study, which was published in the American Heart Association journal Circulation: Arrhythmia and Electrophysiology, is now set to follow the patients for an additional five years.
The FDA approved its first leadless pacemaker in 2016, with Medtronic’s Micra greenlighted for atrial fibrillation and other irregular heartbeats. A newer version, the Micra AV, was approved in January 2020. A competing device from Abbott was approved last year, while Boston Scientific has been developing its own modular option.
As the market began to heat up, the FDA reemphasized the potential risks of the procedure in late 2021, namely of puncturing the heart wall during placement, even among adults. While these cases are rare, and happen in about 1% of procedures—a similar total rate compared to wired pacemakers—when these perforations do happen the consequences tend to be more severe, the agency said.
“Leadless pacemaker technology is the wave of the future,” Shah said. “This is an excellent technology that may be offered to a wider pediatric population.
“However, 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 pediatric patients will likely require pacing for the rest of their lives, which is several decades after implantation,” he said.