Device Helps Heart Transplant Candidates While They Wait for Donor

A new generation of implanted heart-assisting pump does very well at helping severely ill heart-failure patients survive, and thrive, until they receive a heart transplant, a new national study shows.

The HeartMate II left ventricular assist device is implanted in the chest and surgically attached to the bottom of the heart’s left ventricle and the ascending aorta. A tube leads out of the body to the device’s controller and battery pack, which are worn on a holster. And, in addition to helping 75 percent of patients stay alive for at least six months or until a donor heart became available, the device also helped patients’ original hearts regain function and allowed their other organs to heal by restoring blood flow. One patient recovered so fully that a transplant was no longer needed. Patients’ quality of life also improved significantly. The study results are published in the August 30 issue of the New England Journal of Medicine by a team co-led by a University of Michigan Cardiovascular Center surgeon and a Washington Hospital Center cardiologist. The experimental device is called the HeartMate II^(R) left ventricular assist device or LVAD. It is one of four in a new generation of heart-assisting implants that push the blood out of the heart in a continuous flow, rather than a pulsing flow approach used in older devices already on the market. It is also much smaller than the older devices – about the size of a D-cell battery – giving it the potential to help more women, teenagers and smaller men with end-stage heart failure whose bodies aren’t big enough for other devices. It’s also quieter and has a smaller tube leading into the implanted device from the controller and battery pack that are worn outside the body. The study was designed and funded by Thoratec^(R) Corporation, which makes the HeartMate II and its predecessor, the HeartMate XVE LVAD, which is already on the market. But the study’s authors had independent access to the study data to prepare their analysis. The HeartMate II is the size of a D battery, allowing it to be placed in smaller patients than previous heart-assisting devices. Although the study did not directly compare the HeartMate II device with any other device, the results give further evidence that the new device is more reliable than previous heart-assisting implants. In fact, 68 percent of the 133 patients in the study were still relying on the device after one year while remaining on the heart transplant list. The same clinical trial also includes patients who aren’t eligible to receive a heart transplant, and received the devices as a long-term “destination therapy.” “As a bridge to transplant, the HeartMate II is showing excellent survival, good recovery potential for the heart, kidneys and liver, and a favourable impact on quality of life,” says Francis Pagani, M.D., Ph.D., co-lead author of the new paper and the director of the U-M Cardiovascular Center’s Center for Circulatory Support. “These results suggest it would be a very good addition to the options that physicians have for treating patients who require ventricular assistance while they wait for a new heart, and that it has the potential to last years rather than months.” Pagani is an associate professor of cardiac surgery at the U-M Medical School and has led U-M’s participation in numerous clinical trials of heart-assisting devices, including the trials of the original HeartMate device and the pilot HeartMate II trial that preceded the large trial whose results are reported today. Keith Aaronson, M.D., M.S., medical director of U-M’s heart failure program, is a co-author of the new paper.The co-lead author on the paper is Leslie Miller, M.D., a noted cardiologist formerly at the University of Minnesota who is now the director of cardiology programs at Washington Hospital Center.Currently, according to the United Network for Organ Sharing, adults who need a heart transplant wait an average of 170 days, but nearly 30 percent are still waiting even after two years on the transplant list. As of August 24, 2,640 Americans of all ages are waiting for a heart transplant. The new study included 133 patients, and assessed the device’s ability to support patients for six months, or until they received a transplant or recovered heart function, whichever came first. The researchers assessed patients’ functional heart status, as measured by their class of heart failure severity and their ability to walk for six minutes, as well as kidney (renal) and liver (hepatic) function, which are usually diminished by the decreased blood flow from a heart failure patient’s heart. The patients’ quality of life was measured using two standard questionnaires that assess everything from patients’ ability to enjoy social activities, to their physical day-to-day symptoms and mental health. Three-quarters of the study participants were men, with an average age of 50. Two-thirds of the patients had heart failure not related to an ischemic cause such as a heart attack – and all were in the most severe stage of heart failure, called class IV. Many had already received other heart-assisting technologies including pacemakers and implanted defibrillators to regulate their heartbeats; 41 percent had pre-surgery help from an intra-aortic balloon pump. In all, 100 of the patients had successful outcomes by the end of six months, with 56 receiving transplants, 43 remaining on the device and one recovering enough to allow the device to be removed. But the 25 deaths in the study before six months, including 18 patients who died before leaving the hospital, show that serious complications do occur even with the newer generation of device due to the acuity of illness of these patients. Many patients experienced bleeding related to blood-thinning drugs used with the device.But nearly all patients experience cardiac recovery so significant that by the end of three months they were moved to a less-severe stage of heart failure. There were significant improvements in quality of life scores and liver and kidney function. (Source: New England Journal of Medicine 2007; 357(9): 885-96 : Kara Gavin : University of Michigan : November 2007)