By Crystal Phend, Senior Staff Writer, MedPage Today
Published: May 12, 2013
Reviewed by Robert Jasmer, MD; Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Nurse Planner
DENVER -- A small leadless device implanted via a catheter into the heart appears to be feasible for single-chamber pacing, a first-in-man study showed.
The leadless cardiac pacemaker was successfully implanted in 32 of 33 patients attempted (97%) and performed for pacing the same as expected with traditional lead-based pacemakers, Vivek Reddy, MD, of Mount Sinai School of Medicine in New York City, and colleagues found.
"This is a relatively small feasibility study but raises the possibility of eliminating what has been the weakest link in pacemakers: the lead," Reddy told attendees during a late-breaking session at the Heart Rhythm Society (HRS) meeting here.
Standard pacemakers are highly reliable, but the risk of complications range from about 7% to 8% over the life of the device, including lead fracture, infection, and pocket hematomas, he noted at an HRS press conference.
Eliminating the surgical pocket isn't such a big deal, because the implantation is such a minor surgery, commented Gordon Tomaselli, MD, of Johns Hopkins University in Baltimore and a past president of the American Heart Association.
."That's not the game changer here, the game changer is no lead. You can ask anybody who has done this for a long time; leads are the bane of our existence," he said in an interview with MedPage Today. "And if you can easily get these devices out and replace them, it's going to be great for selected patients."
The novel pacemaker is the size of a AAA battery and is implanted by screwing the end into the heart tissue. It can be retrieved or repositioned by simply grabbing the end with a snare and unscrewing it.
Two such cases were documented in the study:
Case 1: Reposition the pacemaker into the right ventricular apex after it had inadvertently been placed in the left ventricle via a patent foramen ovale
Case 2: Replace the pacemaker with an implantable cardioverter-defibrillator (ICD) due to repeated syncope and spontaneous ventricular tachycardia after discharge home with the leadless device
The explantation took 6 minutes in the first case and 13 minutes in the second.
"This is proof of principle in at least two patients," Reddy said.
Preclinical work showed that the device could be removed just as easily at 6 months, although that hasn't been tested in humans yet, Reddy pointed out.
He said it also is expected to be "inherently" MRI compatible, because "magnetic induction can't reach a leadless pacer," although this also hasn't been tested.
The device uses a lithium composite phosphate battery that should last 8 to 17 years, dependent on pacing parameters.
A major problem in the trial was a single case that wasn't successfully implanted. That 70-year-old patient sustained a cardiac perforation and tamponade during implantation and then died from a large right-sided stroke in the hospital 5 days after the procedure.
The only other adverse event among the 33 cases in the LEADLESS first-in-man study was a minor groin hematoma that didn't require treatment.
The device is going into commercial sale in Europe this year, with a large multicenter study anticipated to start in the U.S. next year.
It is only capable of single chamber pacing currently, but it is being developed for atrial use to allow multi-chamber pacing, Reddy said.
There's little chance the technology could be developed as an ICD, Tomaselli noted.
"The capability to deliver large amounts of energy isn't there," he explained. "It's exclusively for pacing. The ICD lead does a lot of things, not only detect heart rate but also some rhythm discrimination. This device is limited in that regard."
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