World’s Tiniest Pacemaker Implanted Without Surgery

The world’s smallest, minimally invasive cardiac pacemaker was successfully implanted in 99.2 percent (719 of 725) of patients participating in an international clinical trial.

The findings also showed that the Micra TPS— about the size of a large vitamin— met safety and effectiveness endpoints with wide margins.

Approximately 96 percent of patients experienced no major complications, which is 51 percent fewer than what is normally seen in patients with conventional pacing systems. Major complications included cardiac injuries (1.6 percent), complications at the groin site (0.7 percent), and pacing issues (0.3 percent).

Michael S. Lloyd, associate professor of medicine at Emory University School of Medicine, said:

“We were pleased to participate in this important trial, as this will likely be the way pacemakers are implanted in the future. The outstanding results are very encouraging and will allow us to continue to offer this novel device as a safe alternative to our patients.”

Lloyd, a cardiac electrophysiologist, implanted the first Micra TPS in April 2014 at Emory University Hospital. He says there are an estimated 3 million people living with pacemakers, and about 600,000 pacemakers are implanted in the world every year.


The pacemaker is delivered via a catheter through the femoral vein and positioned inside the right ventricle of the heart. (Credit: Medtronic)

During the procedure, the tiny device— approximately one-tenth the size of a conventional pacemaker— is delivered through a catheter inserted in the femoral vein to the inside of the heart. Once positioned, it securely attaches to the endocardial tissue of the heart wall and sends electrical pulses to the heart through electrode tips whenever it senses an abnormal heart rhythm.

Unlike conventional pacemakers, the new device doesn’t require the use of wires, known as “leads.” These leads, threaded through blood vessels to connect to the heart, are sometimes the source of serious medical complications such as infection and vein injury.

Another important difference between the new device and traditional pacemakers is that implantation of the Micra TPS doesn’t require a surgical incision and the creation of a “pocket” under the skin. Conventional pacemakers require a more invasive surgery.

“By not creating a pocket and implanting a rigid device directly below the skin, it eliminates another potential source of complications and any visible sign of the device,”

says cardiologist Mikhael El Chami, associate professor of medicine, who is also implanting the Micra TPS device at Emory.

Dwight Reynolds, M.D., et al.
A Leadless Intracardiac Transcatheter Pacing System
NEJM November 9, 2015DOI: 10.1056/NEJMoa1511643

Top Photo: courtesy Medtronic