November 15, 2010 - An experimental pump implanted in patients waiting for a heart transplant works as well as approved devices, according to trial results presented at the American Heart Association’s Scientific Sessions 2010.
The ADVANCE study found that the HeartWare HVAD left ventricular assist device system produced similar outcomes to bridge-to-transplant pumps that have already been approved. The trial studied the device in patients with advanced heart failure.
Among HVAD patients, 92 percent survived for 180 days with the pump, received a transplant or had recovered enough to have the device removed – all considered successful treatment. Similarly, 90 percent of control patients waiting for heart transplants on approved pumps were treated successfully. Nearly one year after implantation, 91 percent of HVAD patients and 86 percent of controls had survived, a difference that is statistically insignificant.
“With this success rate, doctors and patients should have increased comfort with a ventricular-assist device as a bridge to transplant,” said Keith Aaronson, M.D., M.S., lead author of the study and associate professor of internal medicine and medical director of the Heart Transplant and Mechanical Circulatory Support Programs at the University of Michigan Medical Center in Ann Arbor, Mich. “These patients don’t just survive to a transplant, they feel better and can be much more active.”
Two types of these surgically implanted devices are approved for use. First generation devices are known as pulsatile-flow because they pause between pumps to fill with blood, creating a pulsing rhythm similar to the heart’s beat. The newer, more durable, continuous-flow pumps continually propel blood outwards, so flow is less pulsatile.
“The results of ventricular assist device therapy have improved dramatically in recent years with the advent of continuous-flow pumps,” Aaronson said. “The commercially available continuous-flow pump is an excellent pump, but all would agree that there is room for improvement.”
The HVAD is also a continuous-flow pump, but is smaller in size. Part of it is implanted directly into the heart’s the left ventricle, and the remainder is positioned within the space surrounding the heart. In contrast, other continuous-flow devices are placed in the abdomen within a surgically created pocket.
While axial devices propel blood in the direction of flow, centrifugal devices, such as the HVAD, propel blood outward from the center of a spinning disc. The disc is suspended by magnets and the blood itself. Centrifugal flow devices may provide greater pulsatility, which could reduce the incidence of internal bleeding. It may also reduce arrhythmias.
For more information: www.americanheart.org