DALLAS, May 28 – A new implantable device that gives failing hearts a boost while patients await a heart transplant appears to be reliable and safe, researchers report in today’s rapid access issue of Circulation: Journal of the American Heart Association.
The study followed the first 10 U.S. heart failure patients implanted with a new generation of the left ventricular assist device (LVAD) known as the Jarvik 2000. The left ventricle is the chamber of the heart that does most of the work to pump blood into the body.
The device is a bridge-to-transplant step for people waiting for a new heart. The patients (seven men and three women, average age 51) were in severe heart failure and facing imminent death in intensive care units. They were also too physically small to qualify for any of the other bridge-to-transplant left ventricular assist devices, says O.H. Frazier, M.D., lead investigator for the device that has been under development for more than a decade at the Texas Heart Institute and St. Luke’s Episcopal Medical Center in Houston.
The study found that the Jarvik 2000 increased the heart’s ability to move blood through the body (cardiac index) considerably – by 43 percent within 48 hours of implantation. Drugs to support the heart muscle’s contraction became unnecessary.
Eight patients underwent physical therapy and improved from severe heart failure (New York Heart Association Class IV) to mild heart failure (NYHA Class I). Although the study protocol required the patients to remain at the hospital, they were able to resume normal activities – such as walking outdoors and eating in the cafeteria – while awaiting a transplant. The device was used for an average of 84 days.
This article follows another study published in Circulation’s May 14 issue in which Frazier and Stephen Westaby, Ph.D., M.S., implanted the Jarvik 2000 as a non-bridge therapy in four patients in the United Kingdom who were not eligible for transplant. Three of them are still alive, the first now nearing two years. “At this early stage, the Jarvik 2000 seems to hold much promise for many patients with heart failure,” writes noted heart surgeon Denton A. Cooley, M.D., the founder of the Texas Heart Institute, in an editorial that accompanies the most recent Circulation article. “This [study] showed that it can safely support patients to transplantation.”
Cooley adds that the device could also be a possible destination therapy for patients who do not respond to medical therapy or whose conditions deteriorate rapidly. Heart failure patients who still have some left ventricle pumping ability would be candidates for the Jarvik 2000.
The American Heart Association estimates that about 4.8 million Americans are living with congestive heart failure (CHF), which kills more than 50,000 people each year in this country. In contrast to the other devices, which require fairly extensive implant operations, the Jarvik 2000 is small enough to be implanted inside the heart’s pumping chamber during a surgery that requires little or no time on a heart bypass machine, Frazier says. The device is made of titanium with only one moving part – a tiny vaned impeller – in an attempt to reduce the chances of blood clot formation and bacterial adhesion. No blood clots were seen in the seven devices that were removed during the transplant surgeries, the researchers report. Nine of the 10 patients received drugs to guard against blood clots. The tenth patient, who could not take those drugs because of chronic bleeding from a gastric ulcer that required cauterization and surgical resection of the bowel, was supported for 244 days without anticoagulation medication. The device presented only three minor technical problems during a cumulative total of 812 days of support. All problems were resolved quickly with no adverse consequences.
Frazier says the Jarvik 2000 is so different from the other LVADs currently available that the others should be reclassified. “The Jarvik 2000 represents the only true left ventricular assist device because it allows the heart to provide the pulse (beat),” he says. “That makes it much smaller than conventional left ventricular assist devices (LVADs). Those devices, which also provide the beat, capture the entire output of the heart’s left ventricle pumping chamber.” The device features electrical wires that thread out of the body and attach to a rechargeable battery pack that fits in a bag that can be worn on the waist or carried on the shoulder as well as a speed control that the patient can adjust to accommodate increased physical activity. After 48 hours, average cardiac index had improved by 22 percent even with the device turned off, Frazier notes.
“The Jarvik 2000 was designed to be reliable, easy to implant, and simple to operate,” researchers write. “In our series of 10 patients, the device met all of these goals.”
Co-authors include: Timothy J. Myers, B.S.; Igor D. Gregoric, M.D.; Tehreen Khan, M.D.; Reynolds Delgado, M.D.; Mihai Croitoru, M.D.; Kathy Miller, B.S.; Robert Jarvik, M.D.; and Stephen Westaby, Ph.D., M.S.
Materials provided by American Heart Association. Note: Content may be edited for style and length.
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