Dual-Chamber Implanted Pacemaker Detects Cardiac Movement

A miniaturized device offers patients with AV block an advanced leadless technology at one-tenth the size of a traditional pacemaker.

The Medtronic (Dublin, Ireland) Micra AV provides atrioventricular (AV) synchrony capabilities, thanks to a built-in three dimensional (3D) accelerometer that can sense the back and forth movement of the heart, and can therefore coordinate pacing of the ventricle that it is synchronized with the contractions of the atrium. The Micra AV pacemaker is identical in size and shape with the original Micra Transcatheter Pacing System (TPS), with an estimated 12-year battery life, and is approved for full body 1.5 and 3 Tesla scans magnetic resonance imaging (MRI) scans.

Micra AV is delivered via a minimally invasive percutaneous catheter through the femoral vein and is then positioned inside the right ventricle, directly attached to the heart via small nitinol tines that hold it and the electrodes in place; it can be repeatedly repositioned to make sure that heart activity and low electrical thresholds are at optimal levels. Once positioned, the device responds to patients' activity levels by automatically adjusting therapy. And as it does not require a subcutaneous surgical pocket to be created, potential complications are eliminated.

“Since revolutionizing medicine with the first battery-powered cardiac pacemakers, Medtronic has continued to develop pioneering pacing technologies, culminating in the first miniaturized, leadless pacing portfolio for physicians and their patients,” said Rob Kowal, MD, PhD, of the Vascular Group at Medtronic. “The introduction of Micra AV reinvents our own innovation, bringing the many benefits of leadless pacemakers to more patients.”

“With the approval of Micra AV, more pacemaker patients qualify for a new treatment option that offers the advantages of leadless pacing, including a minimally invasive implant procedure and a cosmetically invisible device,” said cardiac electrophysiologist Larry Chinitz, MD, director of the NYU Langone Heart Rhythm Center (New York, NY, USA). “Although complications with traditional pacemakers are infrequent, when they occur, they’re expensive to treat and can be invasive for the patient. Real-world use of Micra has shown a 63% reduction in major complications compared to traditional pacemakers.”

Within the right atrium of a normal heart is a natural pacemaker that sends an electrical stimulus that travels from the pacemaker (SA node) to the ventricles (AV node). In the presence of an AV block the transfer of the electrical nerve conduction that regulates the normal, rhythmic, pumping action of the heart muscle is interrupted or slowed. If the heart block occurs in the fetus or newborn, the condition is known as congenital heart block.

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