World’s tiniest pacemaker debuts: about 1 inch long

Medtronic in 2017 releases Micra TPS, a tiny, leadless pacemaker. (Medtronic)


Billed as the world’s smallest pacemaker, Medtronic’s new Micra TPS (Transcatheter Pacing System) is about the size of a large vitamin capsule.

At about one-tenth the size of a regular pacemaker, which is about the size of a silver dollar, the one-inch device is small enough to be delivered through a catheter near the groin and implanted directly into the heart where it is attached with small, sharp prongs on the end of the device.

Pacemakers are surgically implanted devices that generate electrical impulses that correct irregular or stalled heart beats. A normal heart rate is about 60 beats per minute. Pacemakers monitor abnormal heart rates and generate electrical impulses that cause the heart to contract or beat normally in response to the patient’s activity level.

Dr. Sujoya Dey is a cardiac electrophysiology specialist, who specializes in the diagnosis and treatment of cardiac disease at Marin General Hospital. She said she has implanted “countless” pacemakers over the years but, “This is completely different.”

Aside from the size, one of the biggest advantages of the self-contained Micra TPS is that it has no wire leads. Instead, Dey said, it’s attached directly to the heart wall with the tiny prongs, which deliver electrical stimulation via an electrode on one end.

Nearly 1 million people worldwide are implanted with pacemakers each year, according to Medtronic, which has locations in Santa Rosa and all over the world. The Mira is manufactured in Minnesota.

According to Medtronic, there have been more than 10,000 Micra implants worldwide since its introduction.

The first external pacemaker was developed in the 1940s. The pulse generator was worn on the belt or strapped to the body with electrodes placed over the heart area.

Over the years they have undergone transformations, but for the last decade or so they have remained pretty much the same, Dey said.

The Micra device was introduced in 2013 and used in Europe before the FDA approved it for use in the U.S. in April 2016.

The Micra is not recommended for patients who are severely obese, or who have an intolerance to materials in the device or the blood thinner heparin. Patients also must have veins that are able to accommodate the size of the pacemaker.

The Micra is also a single-chamber pacing system. It paces only the right ventricle of the heart. As the heart has four chambers through which blood flows, patients who require dual-chamber pacing will still need to go with a traditional pacemaker.

A traditional pacemaker is implanted under the skin near the collarbone. Wire leads run from the pacemaker to the heart and provide an electrical connection between the pulse-generating device and the heart.

However, there can be complications with the leads which can sometimes malfunction, fray, break or wear out, requiring surgery.

The Micro lasts about the same amount of time as a regular pacemaker, seven to 10 years before the batteries die.

The procedure to implant the Micra also takes about the same amount of time to perform as the regular pacemaker, about 45 minutes.

But whereas a regular pacemaker is taken out and replaced, the Micra is left in the body, and another one is implanted.

“It gets enmeshed in the tissue,” Dey said.

People using the Micra, the same as those using traditional pacemakers, must follow some precautions. Medtronic recommends keeping items containing magnets at least 6 inches away from the implanted pacemaker. This includes cell phones, MP3 players, headphones and magnetic therapy products, as the energy can interfere with the electrical stimulation.

The Micra is also much more costly, than previous pacemakers. Medtronic is not releasing the cost, but the estimates are about $10,000 with the Micra compared with conventional pacemakers that average about $2,500, according to Modern Healthcare, a web-based healthcare business news and research outlet.

However, Dey said the advantages are evident.

“Patients with the old pacemakers can touch and feel it, and see it every time they look in a mirror,” she said. It’s a constant reminder that there is a foreign object in their body and their heart needs assistance to beat.

Not having that constant reminder makes for less stress and a quicker recovery, Dey said.

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