Leadless Pacemakers Show That Less is More in Matters of the Heart

Miniaturization seems to be the order of the day when it comes to heart devices, especially pacemakers. How do the miniature, leadless pacemakers from St. Jude Medical and Medtronic stack up?

February 20, 2014

4 Min Read
Leadless Pacemakers Show That Less is More in Matters of the Heart

In recent months, product announcements of cardiac devices from major device makers have had a common theme: miniaturization.

The trend is clear - when it comes to the heart and cardiac devices, it appears that less is more.

On Feb. 6, St. Jude Medical announced that a doctor performed a groundbreaking procedure in the U.S. when he implanted a miniaturized, retrievable, leadless pacemaker in a 83 year old man to help control his irregular heart rhythm.

St. Jude was referring to the Nanostim pacemaker, the world’s first leadless pacemaker that the Minnesota device company acquired when it bought Sunnyvale, California-based Nanostim in 2013 for $123.5 million.

It’s size? It’s less than 10% of the size of a conventional pacemaker.

“This is one of the most important technological achievements for patient care in pacing in my lifetime,” said Dr. Mark Carlson, St. Jude’s global clinical affairs & chief medical officer in a recent interview. “The only thing I can think of that really rivals this is the advent of dual chamber pacing.”

St. Jude received CE Mark for the Nanostim pacemaker in October.

Meanwhile Medtronic also recently made news about its own rival leadless pacemaker. Back in December, Medtronic announced the first-in-man implant for its Micra TPS pacemaker. On Thursday, it said that a doctor had performed the first U.S. implant of what it bills as the world’s smallest, minimally-invasive pacemaker.

“Micra TPS is an example of the significant investment we have made in disruptive technology, specifically the miniaturization of implantable cardiac devices," said Pat Mackin, president of the Cardiac Rhythm Disease Management business and senior vice president at Medtronic, in a news release. "Less invasive, miniature device technologies show strong promise in improving patient outcomes and implant procedure efficiency.”

Both products use a catheter that can deliver the implant instead of conventional pacemakers that need to have a surgical incision in the chest and the creation of a pocket under the skin where it resides.

But there are differences.

Medtronic’s device is 30% smaller than the Nanostim pacemaker from St. Jude, said Joey Lomicky, a Medtronic spokesman in an email. He added that "unlike screw-in fixation-based devices, the [Micra pacemaker] design includes active fixation tines (tines that actively attach into the tissue) that keep the device in place in the heart. The tines, which are electrically inactive, engage with the ventricular wall to hold the device in place and provide great stability. The tines are also designed to be easily disengaged without causing trauma to the cardiac tissue if the device needs to be repositioned."

St. Jude's CMO also enumerated differences between the two devices that he believes gives the Nanostim device an edge:

The introducer sheath - the sheath through which you implant the device into the vein - for the St. Jude Medical leadless pacemaker is smaller in diameter than what is required for the Medtronic pacemaker. This is an important difference in that it may impact access for what needs to be done to stop bleeding after the procedure.

In addition, our device is fixed to the heart via a helix which is very similar to what is used today with conventional pacemaker leads. That helix is key because it is part of the overall system that enables our device to be retrievable and to be potentially retrievable over the entire lifetime of the device.

The fixation system for the Medtronic device that I have seen is much different and involves what I can best describe is grappling hooks.

There are several scenarios where the fixation device is important....There are many patients who will outlive their pacemakers particularly younger patients and this device is designed to be retrievable at the point when the patient needs a new device and you can take one out and put one in and you won't need to have two devices in the heart.

No matter which device is superior and wins in the marketplace, the ultimate winner is the American patient who in the near future will be able to access two versions of a groundbreaking technology.

 [Photo Credit: iStockphoto.com user zbruch]

-- By Arundhati Parmar, Senior Editor, MD+DI
[email protected]

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