An implantable defibrillator using wires that may pose less risk than widely sold devices shocked faulty hearts back into rhythm in almost all cases, according to a 60-patient study funded by the product’s maker.
Defibrillators now use leads, which are flexible wires threaded through veins to the heart muscle, to deliver life- saving jolts of electricity. The device in the study was made by closely held Cameron Health Inc. of San Clemente, California. That product uses a lead that is surgically placed beneath the skin and doesn’t connect directly to heart muscle, according to research published today in the New England Journal of Medicine.
Faulty wires led to recalls and safety warnings for defibrillators made by Boston Scientific Inc. and Medtronic Inc. Wires are difficult to implant in some patients and can fracture after years of use, leading to potentially life-threatening failures, said Richard Page, a department chair at the University of Wisconsin’s School of Medicine & Public Health, in Madison.
“This could be a game changer, if indeed this is the direction this technology goes,” said Page, who is also president of the Heart Rhythm Society, a Washington-based group of cardiologists.
St. Jude Medical Inc., based in St. Paul, Minnesota, competes with Minneapolis-based Medtronic and Natick, Massachusetts-based Boston Scientific in the $4.3 billion U.S. market for the devices.
Page, who wasn’t involved in the research, said the study will need to be replicated in a larger trial. If approved by regulators, the Cameron device would be the first of its kind sold in the U.S.
The device was implanted in 61 patients with abnormal heart rhythms, in two studies in New Zealand and Europe. One patient was converted to a conventional device during the trial, leaving 60 test subjects.
The Cameron defibrillator detected ventricular fibrillation, a chaotic heart beat that can lead to cardiac arrest and death, in all of the patients, according to the study. The device shocked the heart back to a normal rhythm in two consecutive episodes of ventricular fibrillation in all but one of the patients, the researchers said.
“This therapy is an alternative to the transvenous approach,” said Gust Bardy, the study’s lead author and a cardiologist at the Seattle Institute for Cardiac Research. “We’re early in this, and I don’t want to overclaim the value.”
Bardy helped start Cameron Health after one of his patients died, in 1995, of sudden cardiac arrest when a defibrillator wire broke, prompting him to develop an alternative device. He is a director of Cameron Health and owns shares, according to the company.
The Cameron defibrillator is the size of a small cell phone and is implanted beneath the skin of the left arm, Bardy said. It uses a wire that runs from the device and up the chest to about two inches from the heart, he said. Because it is further from the heart, the device delivers an electrical jolt more than twice as powerful as the jolt from a conventional defibrillator connected directly to the heart, Bardy said.
The product has potential advantages, including a less risky surgical procedure because the doctor doesn’t need to thread wires through the veins, Page said. Conventional devices also require the doctor to use an imaging test known as X-ray fluoroscopy, which provides surgeons with a detailed image of the blood vessels but exposes the patient to a higher dose of radiation than standard X-rays.
Also, wires used in the Cameron defibrillator may be less subject to fracture, said Martin Burke, director of the Heart Rhythm Center at the University of Chicago Medical Center, which was one of the sites for the study.
“Leads don’t last forever because the heart is a moving chamber and pumping organ that is a less than ideal environment for the mechanical materials,” Burke said.
David Steinhaus, medical director of cardiac rhythm product for Medtronic, called the device “an interesting technology with some limitations,” including an inability to “pace” the heart back into normal rhythm without a shock.
Medtronic stopped selling its Sprint Fidelis defibrillator wires in 2007 after the leads began fracturing. The company said in March that the wires “may have been a possible or likely contributing factor” in 13 deaths. The company has since substituted a different lead, although the Fidelis wires remain implanted in an estimated 175,000 patients worldwide, said Chris Garland, a Medtronic spokesman.
The Fidelis incident has made physicians reluctant to recommend the devices to younger patients, in particular, Burke said. About 20 percent of patients who might benefit from defibrillators receive the devices, he said.
A safer defibrillator may help expand the use of the devices to younger patients whom doctors are reluctant to expose to the risk of wire fractures and other complications, Burke said.
Cameron Health began selling its defibrillator in the U.K. and the Netherlands this year after receiving approval from European regulators last June, said Kevin Hykes, president and chief executive officer, in a telephone interview. In March, the company began enrolling the first of 330 patients in an international trial to help gain U.S. regulatory approval in the second half of 2011, he said.
“We believe this is a significant advance in the treatment of sudden cardiac death,” Hykes said. “We also think it might bring new patients into the ICD market.”
Cameron Health has received an undisclosed amount of venture capital from Versant Ventures and Delphi Ventures, both in Menlo Park, California; Three Arch Partners in Portola Valley, California; and PTV Sciences in Austin, Texas, Cameron Health said.