Stony Brook doctor implanting world’s smallest pacemaker

Nearly a dozen Long Island heart patients have received a cardiac pacemaker that is shaped like a bullet and is so small the self-contained device is inserted directly into the heart without surgery.

“The design is totally different than any of the others that we use,” said Dr. Eric Rashba, director of the Heart Rhythm Center at Stony Brook University Hospital. “It’s basically like a little bullet with prongs and is for people who need pacing in only one chamber of the heart.”

Rashba said the device, which has no wires, is designed for patients with bradycardia, which means having a significantly lower than normal heart rate. Adults generally have a resting heart rate in the range of about 60 to 100 beats per minute. Some bradycardia patients have a resting rate of only 30 or 40 beats every 60 seconds.

The implant at 1.01 inches is the world’s smallest cardiac pacemaker. As such, it is one in an increasing number of gee-whiz medical devices — incredibly shrunken implants of all kinds — that may be Lilliputian in size, but are capable of gargantuan physiological improvements.

Since the 1960s when they first became widely used, cardiac pacemakers have been steadily shrinking in size. Standard ones are about the diameter of a vanilla wafer cookie.

Another teeny, cylindrical pacemaker called the Nanostim, a product of Abbott Laboratories, is about an inch-and-a-half in length. While small, it is not the smallest. Nanostim is also a single-chamber device. However, in October 2016, while still under study, implantation of the device was stopped because of battery problems and a loss of telemetry. The problems have since been resolved, according to Abbott.

With the 1.01-inch pacemaker, its developer has produced what some doctors view as a silver bullet for about 10 percent to 20 percent of people with bradycardia, which can be caused by aging, heart attack or infection that damaged the heart.

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“This is an example of increasing miniaturization and a quantum leap in how we deliver the therapy,” Rashba said in a recent interview.

The pacemaker that he is implanting is called Micra and is manufactured by Medtronic Inc. It has been placed in the hearts of about 10 Stony Brook patients since January, Rashba said.

Micra was designed for patients whose heart rate problem involves only one of the heart’s four chambers. Most patients in need of a pacemaker have problems involving more than one chamber, Rashba said, noting that even more sophisticated tiny pacemakers are on the drawing board.

Medtronic’s Micra was approved by the U.S. Food and Drug Administration in 2016, the first such device to pass U.S. regulatory hurdles.

Doctors who insert the implant must undergo substantial training in how to place the device directly into a heart chamber, according to product data from Medtronic.

Conventional, bulkier pacemakers are surgically implanted in the shoulder region. Those devices have a lead wire that is threaded from the pacemaker into the heart.

Rashba and his team implant the Micra in a catheterization laboratory where the device is placed aboard a catheter and moved northward to the heart through the femoral artery in the leg. The device lasts for about a decade. And because it is so small, another one can be added to the same heart chamber years down the road when the original one loses power, Rashba said.

More than 4 million patients globally have pacemakers, and 600,000 new patients receive one annually, World Health Organization statistics show. The late Dr. Judah Folkman of Harvard University invented the first implantable heart pacemaker about 60 years ago.

Miniaturization is the key to improved cardiac implants in the future, Rashba said.

As other cardiac devices follow the path of pacemakers — becoming not only smaller, but also losing wires and external connections — Rashba foresees numerous health advantages.

For example, he envisions a day when LVADs — left-ventricular assist devices — are miniaturized and their external tubing is eliminated. In so doing, the potential for infection would be dramatically diminished. “If they could be miniaturized, that would be amazing,” Rashba said.

“Miniaturization and improvement in technology will continue to offer a lot of benefits,” he said.