Medtronic's itty-bitty pacemaker is implanted directly inside the heart

Medtronic on Monday announced the first human implant of the world's smallest pacemaker, a vitamin-sized device that is implanted directly inside the heart.

The Fridley-based medical technology giant said its Micra Transcatheter Pacing System is just one-tenth the size of a of a conventional pacemaker. Medtronic officials called the technology "game-changing" in what is expected to become a $5 ­billion global market by 2015.

"We now have a technology that has the potential to improve outcomes and reduce the cost of the therapy," said Pat Mackin, president of the Cardiac Rhythm Disease Management business and senior vice president at Medtronic.

The device is delivered into the heart through a catheter inserted in the femoral vein. Once positioned, it is securely attached to the heart wall and can be repositioned if needed. The pacemaker doesn't require the use of wires, known as "leads," to connect to the heart. Instead it is attached through small tines, and the pacemaker delivers electrical impulses that pace the heart through an electrode at the end of the device.

The device was implanted in a patient in Linz, Austria, as part of the Medtronic global pivotal clinical trial. The Micra system is an investigational device and is probably ­several years away from availability in the United States.

"Because of its small size and unique design, the Micra TPS can be introduced directly into the heart via a minimally invasive procedure, without the need for leads," said Dr. Clemens Steinwender, head of cardiology at the Linz General Hospital in Austria. "The combination of this novel technology with a transcatheter procedure can benefit patients by potentially reducing pocket or lead complications and recovery times observed with traditional ­surgical pacemaker implants."

In contrast to current procedures, the Micra system implant does not require an incision in the chest and the creation of a "pocket" under the skin. This eliminates a potential source of device-related complications, and any visible sign of the device.

"Micra TPS is an example of the significant investment we have made in disruptive technology, specifically the miniaturization of implantable cardiac devices," Mackin said. "Less invasive, miniature device technologies show strong promise in improving patient outcomes and implant procedure efficiency."

Takes technology to next level

Pacemakers help regulate the heart rhythm for patients with a slow heartbeat. Much of the work over the years has been to develop ever smaller devices with longer-lasting batteries. The Micra system is expected to have an average battery life of 10 years, Mackin said.

Such small pacemakers are seen as, someday, being especially appealing to younger patients because of the lack of a telltale lump beneath the skin and no visible scars. In some countries in Asia, Mackin said, a visible pacemaker lump is considered a sign of disability — meaning the tiny device could help drive new business. Medtronic had nearly $2 billion in pacemaker revenues during its 2013 fiscal year.

Its 10-year battery life may mean it is not right for ­children, he said. But for adults, doctors will be able to easily implant a new pacemaker next to it when the time comes.

"Once that device is anchored in the heart and the scar tissue has formed and the device is encapsulated, you are not going to want to take this out," Mackin said.

The impact of leaving the device behind, and the ease of repositioning or removing it if needed, needs to be studied in the trials, he said.

The Micra provides single chamber pacing — the right ventricle — and would not be used for patients who need dual chamber pacing or for those who also need a defibrillator.

And while the Micra may be the smallest wireless pacemaker to be implanted, it is not the first to do away with leads.

In October, St. Jude Medical announced that it had acquired Nanostim Inc., giving the Little Canada-based medical technology company the world's first commercially available "leadless" pacemaker. The pacemaker developed by Nanostim is about the size of a AAA battery. St. Jude is making the device available in select European markets and the firm said it is beginning clinical trials in the U.S.

Mackin said Medtronic's device is about 30 percent smaller than the Nanostim pacemaker.

Leads are considered the weak link of pacemaker and defibrillator therapy, with the thin wires fracturing or disconnecting over time. Medtronic and St. Jude have had problems with leads, with St. Jude's Riata lead being the most recent to be pulled from the market, after it was discovered that inner wires were coming through the outer insulation.

The Micra study will enroll up to 780 patients at about 50 centers globally. Mackin said the trial will truly be comprehensive and international in scope, with patients being implanted with the device in 17 countries, including China, the Czech Republic, France, India, Malaysia, Japan, Russia and the United Kingdom. Medtronic hopes to enroll U.S. patients in the trial in 2014. Initial results from the first 60 patients, followed up to three months, are expected in the second half of 2014.