Wireless Pacemakers: Rhythm Without Blues

No wires means fewer complications

Traditional pacemakers are implanted under the skin and attached to a wire that is inserted directly into the heart muscle. The device generates a current that travels down the wire to control the heart’s contractions. Complications related to pacemakers are generally related to these wires, known as leads, which can fracture or become infected. Removing them is so complicated and dangerous that many cardiologists won’t even try.

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New solutions investigated

Traditional pacemakers that control heart rhythm are safe and effective, but when issues arise, they are mainly related to the wires that connect them to the heart muscle. Wireless pacemakers are designed to avoid these problems. Because wireless pacemakers have no leads and are not implanted under the skin, they avoid lead-related complications altogether.

Cleveland Clinic electrophysiologists are involved in clinical trials of two different models. Much smaller than traditional pacemakers, the Nanostim looks like an AAA battery; the Micra is about the size of a multivitamin.

The two devices share common features. Both are inserted by catheter directly into the heart, where they help control heart rhythm by speeding up a slow heart and adjusting the rate when a boost of energy is required. Both are single-chamber devices, meaning they can pace one side of the heart, but not both sides. This means they can only be used in patients with a slow heart rhythm (bradycardia) who need pacing on one side of the heart.

To date, more than 200 patients in the U.S. and Canada—seven at Cleveland Clinic—have received the Nanostim device through the LEADLESS II trial. The trial will determine freedom from complications at six months.

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“Our experience at Cleveland Clinic has been quite favorable, but it’s still early. Our first Nanostim was implanted on Valentine’s Day, so we have passed that six-month mark,” says Cleveland Clinic electrophysiologist Daniel Cantillon, MD, who serves as principal investigator.

Cleveland Clinic physicians are also helping to evaluate the Micra device.  This global clinical trial hopes to enroll about 780 patients. To date, Cleveland Clinic has delivered this miniature powerhouse to two patients.

Wireless shocks

Wireless pacemakers are following in the footsteps of a wireless implantable cardioverter-defibrillator (ICD), which has already received FDA approval. Unlike a wireless pacemaker, the S-ICD is inserted under the skin (S stands for subcutaneous). The device has no leads to become infected or fail. Because it is implanted in soft tissue, it can be removed easily and safely, if necessary.

Currently, the S-ICD only acts as shock paddles to jumpstart a heart. It is not yet able to the pace the heart.

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“This is an important limitation. However, the S-ICD is an excellent option for some patients, such as those with heritable conditions that make them vulnerable to sudden death at a young age, like Brugada syndrome,” says Dr. Cantillon.

Although wireless pacemakers and ICDs don’t yet have all the capabilities of traditional models, the possibilities are endless. Cleveland Clinic electrophysiologists expect to participate in clinical trials of many new devices.

“It’s exciting to be part of these clinical trials. As physicians, we always want to serve our patients in ways that are better and safer,” says Dr. Cantillon.

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