A new, less-invasive implantable device for hearts

Raffaele Corbisiero of Deborah hospital.
Raffaele Corbisiero of Deborah hospital.
Posted: February 13, 2014

Internal medical devices that can jump-start stopped hearts are lifesaving for some patients, but the technology has a well-known drawback.

Electrical wires, or leads, must be threaded from a small battery-powered generator through veins into the heart. Placing the electrodes is challenging, and they are prone to malfunction.

Now, a novel type of implantable cardioverter defibrillator (ICD) has done away with the transvenous wiring. Instead, a single lead runs just beneath the skin to the breastbone, where is it anchored with a few stitches. It detects cardiac arrest without directly touching the heart, like an electrocardiogram measures heartbeats through electrodes placed on the chest.

At Deborah Heart and Lung Center in Browns Mills, Raffaele Corbisiero said the new ICD offered a simpler, potentially safer, approach for suitable patients.

"I do a lot of ICD extractions - over 200 a year," often because of defective leads, said Corbisiero, chair of electrophysiology. "Extracting an ICD is higher risk than putting one in, because the wires heal into veins in the heart."

The new skin-deep ICD, or S-ICD, "offers a lot of advantages," he said.

Curtis Perrone, 51, of Toms River, N.J., agreed. His conventional ICD, placed in 2008 at another hospital, developed defective leads - twice. Last month, Corbisiero removed the system because it had become infected, which turned the leads into potentially lethal conduits to Perrone's bloodstream and heart.

"This new ICD should work better," Perrone said, "and is less likely to get infected."

The S-ICD, marketed by Boston Scientific, was approved by the Food and Drug Administration in September 2012 after clinical testing at sites that included the University of Pennsylvania, Hahnemann University Hospital, and Cooper University Hospital.

In addition to those hospitals and Deborah, the S-ICD is now available in this region at Abington Memorial Hospital and St. Mary Medical Center.

Even if it catches on, the new ICD will not replace the older type, because it is not as versatile.

The S-ICD is only for patients at risk of cardiac arrest, either because their hearts are damaged and weak, or because of an electrical abnormality that triggers the chaotic quivering called ventricular fibrillation.

In contrast, conventional ICDs cannot only shock a stopped heart back to pumping, but can also provide pacing that corrects a too-slow or too-fast heartbeat.

In an opinion piece early last year, Minneapolis Heart Institute cardiologist Robert G. Hauser urged a cautious embrace of the new technology. He noted that conventional ICDs, pioneered in the 1970s, weighed less and restarted the heart using less voltage than the S-ICD.

"The immediate use of S-ICDs ought to be limited," Hauser wrote in the Journal of the American College of Cardiology. "The need for more data with this promising device should be paramount at this time."

Other experts believe the S-ICD may vastly expand the use of implantable defibrillators. Although more than 100,000 a year are implanted in the United States - including 25,000 procedures to replace depleted batteries - the complexity of the surgery has been a limiting factor. Many patients are too sick to undergo transvenous implantation, and many physicians lack the skill and equipment.

In any case, even more innovative technology is on the horizon. This month at Mount Sinai Hospital in New York City, an experimental leadless pacemaker was implanted directly inside a patient's heart using a minimally invasive procedure.

The Nanostim, made by St. Jude Medical Inc. of St. Paul, Minn., has a small electrode that protrudes from one end of the device and sends pulses to the heart when it detects a rhythm problem. Clinical testing is underway at 50 centers in the United States, Canada, and Europe.

"The device looks like a little bullet, and it's implanted right in the heart," explained Corbisiero. "In the future, we may have implantable devices that can help patients with blood pressure, heart failure, urinary problems," and more.


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