Published on December 27, 2018

NMMC Offers World’s Smallest Pacemaker

Miniaturized Heart Device Provides Patients with the Most Advanced Pacing Technology Available

TUPELO, Miss.—North Mississippi Medical Center now offers the world’s smallest pacemaker for patients with problematic slow heart rates.

The Micra® Transcatheter Pacing System (TPS) is an implantable cardiac device that provides the most advanced pacing technology at one-10th the size of a traditional pacemaker. Karthik V. Prasad, M.D., a cardiac electrophysiologist with the NMMC Heart and Vascular Institute, performed the first procedure Nov. 5.

“Bradycardia is characterized by a slow heart rate, usually fewer than 60 beats per minute,” Dr. Prasad said. “In general, a slow resting heart rate is a good sign and doesn’t cause any symptoms. However, that’s not the case always.”

Dr. Prasad explains that in some people, slow heart rate can mean the heart is not doing well enough to pump adequate blood to all the vital organs in the body, and this can translate into symptoms, such as lightheadedness or dizziness, fainting, shortness of breath—especially with physical exertion—and sometimes even chest pain. “In the absence of reversible causes, treatment involves a cardiac pacemaker to relieve symptoms by sending electrical impulses to the heart to normalize the heart rate,” he said.

Traditional pacemakers involve surgical implantation of a device in the chest with flexible wires called “leads” extending into the heart. Medtronic’s Micra TPS is 93 percent smaller than these traditional pacemakers—measuring about the size of a large vitamin pill—which makes it cosmetically invisible. More importantly, Micra TPS requires neither the leads going into the heart nor the surgical “pocket” under the chest.

Instead, Micra TPS is small enough to be delivered through a catheter and implanted directly into the heart. “The procedure is similar to a heart catheterization,” Dr. Prasad said. “Under moderate sedation sometimes called “twilight zone,” a large IV catheter is placed in the big vein in the thigh called the femoral vein, through which we gain access to the heart. The Micra pacemaker goes through this catheter and gets implanted in the right bottom chamber—the right ventricle—of the heart under X-ray guidance with the help of fixation anchors that hook on to the heart muscle. Patients will typically go home the next day.”

When compared to a traditional pacemaker, the Micra TPS has a higher implant success rate (99.1 percent), a lower infection rate and 63 percent fewer complications in the first year. These complications are often related to traditional pacemakers’ leads, which can break or become disconnected, or issues related to the chest pocket holding the pacemaker battery. “The lesser the amount of hardware, the lesser the opportunity for something to break,” he said.

Dr. Prasad said the leadless pacemaker is beneficial for patients who have symptomatic bradycardia, especially in the setting of a common irregular heart rhythm problem called atrial fibrillation. Individuals with kidney failure requiring dialysis are historically considered to be at higher risk for infections with traditional pacemakers, and the Micra TPS is a great option in such patients. Other scenarios are patients with defective blood vessels in their chest and neck that make implantation of traditional pacemakers technically difficult.

“Though symptomatic bradycardia is often seen in older people, occasionally young people can have it too. Traditional pacemaker leads, in this setting, can fracture or break over long-term use—mechanical stress from routine use of the joints and arms—not to mention the cosmetic disadvantage of having a scar from the small incision on the chest,” Dr. Prasad said. “Such patients can enjoy an active lifestyle without worrying about causing problems with the pacemaker’s leaders, since the Micra has none.”

The average longevity of the Micra TPS is 10-12 years. For patients who need a replacement, a unique feature enables it to be permanently turned off so it can remain in the body and a new device implanted adjacent to it without risk of electrical interaction. Because the pacemaker is so small, the heart’s right ventricle can hold up to three such devices without any adverse effects.

Like most recently-developed pacemakers, the Micra TPS is also MRI compatible and patients can continue to use their cell phones, microwaves and other electronic devices without any implications. The Micra TPS was approved by the U.S. Food and Drug Administration in April 2016, and is covered by Medicare.

For more information about services at the NMMC Heart and Vascular Institute, call 1-800-THE DESK (1-800-843-3375).

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