Clinical trial tests tiny experimental pacemaker that does not require surgery

Miniature device being studied to see if it may streamline care for those with a slow heart rate

Lamb Moore, a 75-year-old patient at the University of Chicago Medicine, was the first person in Illinois to receive a tiny experimental cardiac pacemaker, implanted directly into the apex of the right ventricle of his heart.

As part of the study underway, placement of this innovative device -- the Nanostim leadless pacemaker from St. Jude Medical -- does not require surgery. It is about the size of an AAA battery, 10 times smaller than a conventional pacemaker, and weighs only two grams. Research to date has shown that it can be securely implanted within the heart using a cardiac catheter inserted through a small incision in the groin.

The Nanostim, currently being tested in a nationwide clinical trial, leaves no visible lump or scar on the chest and does not require the insulated lead wires that connect most conventional pacemakers to the heart.

If this trial confirms previous studies in Europe, this device should allow patients to continue active lifestyles, without fear of dislodging or damaging a pacemaker lead. By avoiding surgery, it may speed recovery and reduce the risk of complications. It can be removed or replaced as needed by cardiac catheter.

"This is a promising application that takes full advantage of miniaturized technologies," said Hemal Nayak, MD, the University of Chicago electrophysiologist who placed Moore's pacemaker in his heart. "This device is remarkably compact and relatively easy to implant. We think it could prove to be a good alternative, especially for patients who have had problems caused by a traditional pacemaker implant involving leads or pocket, or in those patients who may be at higher risk for developing these problems."

The Nanostim pacemaker was developed specifically for patients with bradycardia, a heart rate that is too slow. The device monitors the heart and provides electrical stimulation when the heart does not pump blood fast enough.

Moore became Illinois' first Nanostim patient and research test subject on July 16. He suffers from an abnormally slow heart rate. He had to stop working as a driver at an auto auction. His doctors would not certify him to drive because of the risk that he would pass out.

He also suffers from mycosis fungoides, a form of T-cell lymphoma that primarily affects the skin. It can weaken the immune system.

Moore's doctors had previously implanted two standard pacemakers in a small pocket under his shoulder, with lead wires connecting the device to his heart. But both times, perhaps because of his decreased immunity, he quickly developed an infection surrounding the implant.

"It felt like a big knot in my chest," Moore recalled -- and it had to be removed. After the second implant, his cardiologist, at another hospital, referred him to the University of Chicago's electrophysiology team. They immediately suggested that he enroll in the Nanostim trial, but they had to wait briefly for the study to open up.

"I didn't feel anything when they put it in," Moore said. "No pain at all. I went home the next day with no restrictions. Now I can drive. I even trimmed the hedge."

"Of the three pacemakers I've had," Moore said, "this has been the best one. I can tell it's working. I don't get so worn out, now. I can go all day, and I sleep better at night."

Nanostim is a single-chamber pacemaker, the simplest form of pacing. Approximately 10-15 percent of patients who require a pacemaker could be candidates for this device, according to the manufacturer. The remainder need a dual-chamber or multi-chamber pacemaker.

The experimental pacemaker is currently available in the United States only as part of the LEADLESS II Clinical Trial, a prospective, non-randomized, multi-center study designed to evaluate its safety and effectiveness. In Illinois, the University of Chicago Medicine and Advocate Christ Medical Center are the only centers involved.

Like all implanted pacemakers, the Nanostim is powered by a battery, which should last at least eight years. The battery does not suddenly stop working; it sends signals months in advance that it is getting low. Caregivers assess this at each follow-up visit. If the battery is too low, they can remove the pacemaker via cardiac catheter and replace it with a new one.

While needing further study, cardiologists estimate the Nanostim could function years longer, depending on the energy required to maintain a normal heartbeat. Because bradycardia is more common in older patients, most people who could potentially benefit from this device are in their 70s or 80s. Not all of them will need to replace the unit.

This provides one more tool we can deploy to help patients with heart rhythm disorders. Miniaturization of the technology is leading to better and better ways to diagnose and treat a wide range of rhythm disorders with significantly reduced side effects.

More than four million people around the world have an implanted pacemaker or other cardiac rhythm management device, and more than 700,000 additional patients receive an implant every year.

Although the incidence of pacemaker complications is relatively low (about four percent), when complications occur, they typically involve the leads, which move out of place, degrade or malfunction in about three percent of patients. In about one percent of patients, the pacemaker pocket becomes infected, such as in Moore's case. The Nanostim has no leads and does not require a pocket.

St. Jude Medical, Inc. was awarded the 2014 Innovation Award at Cardiostim 2014, the 19th World Congress in Cardiac Electrophysiology and Cardiac Techniques. The award, which was chosen by a committee of electrophysiologists, recognized the Nanostim leadless pacemaker as the industry's "most innovative product" in the sector of electrophysiology and cardiac techniques.

Physicians hope to enroll approximately 670 patient-subjects in the LEADLESS II Clinical Trial at 50 approved U.S. centers. For more additional information on Nanostim pacemaker technology, visit sjm.com/leadlesspacing.