In a marching band, every musician knows when to play because the drum major signals the beat. Fast or slow, excited or calm, the musicians can stay together. But if the musicians can’t see or hear the drum major, their timing can drift apart. They get out of synch. The rhythm – and the music that depends on it – can fall apart.
Your heart is like that band. The chambers must contract in synch with each other so that your heart pumps blood with that familiar “ba-BUMP, ba-BUMP” rhythm. But in a common condition called AV block, the signals can’t travel from one part of the heart to another the way they should. And when the heart’s chambers don’t beat in synch, the patient can feel fatigued, dizzy, confused and could lose consciousness. It can even be life-threatening.
On March 6, St. Mary’s implanted a new kind of miniature pacemaker that restores the heart’s synchronization without wires or the need to create a pouch under the skin of the chest. In the first procedure of its kind in Georgia, electrophysiologist Amit Shah, MD, and his team at St. Mary’s implanted a Medtronic Micra AV pacemaker directly inside a patient’s heart, just weeks after the federal Food and Drug Administration approved use of the device on Jan. 21.
The Micra AV functions in a radical new way. In a standard pacemaker, wires called leads pick up the electrical signals when the heart’s weak chambers – the atria – contract. The information goes to a unit about the size of a pack of cards implanted under the skin of the chest. That unit then sends a signal through different leads to the heart’s strong pumping chambers – the ventricles – that causes them to contract and pump blood throughout the body.
The Micra AV is different because it needs no leads embedded in the heart and chest and no pouch under the skin. Instead, the device, which is about the size of a large vitamin pill, is attached to the inside of one of the ventricles. It works by sensing the motion of the atria when they contract and then telling the ventricles they need to contract, too.
“The Micra AV is the latest technology for patients with AV block and presents an excellent alternative to traditional pacemakers,” said Dr. Shah, a cardiologist with Oconee Heart and Vascular Center and medical director of St. Mary’s Electrophysiology Laboratory. “Traditional pacemakers are implanted in the upper chest and connected to the heart using leads. This restores electrical synchrony leading to mechanical synchrony between atria and ventricles. Micra AV, on the other hand, uses special sensing algorithms to detect cardiac movement, and restores electrical and mechanical synchrony without the use of any leads. Leadless pacemakers therefore reduce potential complications such as infections and improve quality of life.”
The first procedure at St. Mary’s took only a few minutes. Dr. Shah performed the implantation through a single small incision in the patient’s upper leg. Guided by advanced imaging technology, he navigated the device into the heart through the inside of blood vessels while the patient was under a mild sedative. The patient’s outcome was excellent, and she was able to go home the next day.
“We are now able to achieve AV synchrony with a device the size of a pill, placed in the ventricular apex without [large] incisions, without leads, and a 63 percent lower incidence of complications,” Medtronic quotes Dr. Larry Chinitz, Director of the Heart Rhythm Center at New York University Langone Health. “If this is not a game-changer, if this is not the future of cardiac pacing, I have never witnessed such an event in my career.”
Leadless pacemakers like the Micra AV provide a range of benefits over pacemakers that implant outside the chest wall, Dr. Shah said:
- No “pouch” is needed under the skin of the chest to hold the pacemaker unit.
- No leads need to be implanted to connect the unit to the heart.
- The device is cosmetically invisible, unlike a traditional pacemaker, where the pouch is visible.
- Because implantation does not require the creation of a pouch or embedding leads, the procedure is simpler and less invasive than a traditional pacemaker.
During the COVID-19 pandemic, St. Mary’s continues to perform procedures that are important to the health and wellbeing of our patients, such as the implantation of pacemakers and other cardiac devices. Strong infection control measures are in place as recommended by federal and state authorities to help ensure the safety of our patients, providers and colleagues.
For more information about the Micra AV, see https://www.medtronic.com/us-en/about/news/micra-av-fda-approval.html. For more information about St. Mary’s cardiac services, Dr. Shah, and Oconee Heart and Vascular Center, please visit www.stmaryshealthcaresystem.org.
Diving into the details
The FDA approved the Micra AV based on results reported in 2019 of the MARVEL 2 (Micra Atrial TRacking Using a Ventricular accELerometer) study, which was led by Dr. Chinitz. In the study, patients who received a Micra AV unit were compared to patients who received standard ventricular pacing treatment. 95 percent of the Micra patients achieved 70 percent or greater atrial-ventricular synchrony, while none of the comparison patients did. The study also showed good safety outcomes, with no reports of pauses or rapid heart rate caused by the device.
Like its 2016 predecessor, the Micra Transcatheter Pacing System (TPS), the Micra AV and its computer are powered by a tiny battery with an expected life of 8-13 years. For patients who need more than one heart device over the course of their life, Medtronic designed the Micra with a unique feature that enables it to be permanently turned off so it can remain in the body and a new device can be implanted without risk of electrical interaction. However, the Micra AV also incorporates a feature to enable retrieval if necessary.
The Micra is the first transcatheter pacing system to be approved for both 1.5 and 3 Tesla full-body magnetic resonance imaging (MRI) scans. It is also designed to allow patients to be followed by their physicians and send data remotely via the Medtronic CareLink® Network.
The Micra AV has been granted Medicare reimbursement, allowing broad patient access to the novel pacing technology. Other companies have their own proprietary technology, and their leadless pacemakers will be commercially available pending FDA approval.