The first U.S. patient implanted with a DuraHeart Left Ventricular Assist System (LVAS) from Terumo Heart (Ann Arbor, Michigan) was discharged last week from the University of Michigan Health System (Ann Arbor) 15 days after receiving the device.
The company says the hockey puck-sized DuraHeart LVAS uses a new type of magnetic levitation technology (Mag-Lev) designed to eliminate mechanical contact within the blood flow path thus minimizing the chance of mechanical failure.
Mark White, marketing manager for Terumo Heart, told Medical Device Daily that the Mag-Lev technology is the core benefit of the DuraHeart, as it prevents a lot of the problems associated with other systems in which the impeller is suspended through pressure distribution.
With those systems, he said that when the pump is starting up for the first time, the impeller is just sitting on the bottom of the blood chamber, which can scratch the chamber surface and potentially create a source for cells to start clotting. He added that outside forces can potentially move the impeller, causing flow variations and even some areas of stagnant blood flow.
"Theoretically, if a patient is doing something really active like playing tennis, it's not inconceivable that it could deflect to the point of touching the chamber wall," White said. "You're relying on hydraulic characteristics to keep the impeller constant and centered and that's difficult to do."
The DuraHeart system, on the other hand, is controlled using position sensors to measure where it is and keep the impeller centered in the blood chamber. He compared it to playing with magnets and watching an object quickly snap to the middle of a magnetic field.
"It's rigidly positioned in the center of that chamber, regardless of what happens on the outside it never drifts out of that position," White said. "That gives you very consistent flow patterns ... no stagnant-flow areas, there is never any contact with the chamber wall ... that's really the core benefit."
He said there have not been any problems with blood clots in any of the DuraHeart systems that have been removed from patients, whereas other systems tend to have clotting issues. The company's engineers believe the Mag-Lev technology is responsible for keeping the devices clot free.
News of the first U.S. patient to receive a DuraHeart LVAS came almost simultaneously with HeartWare (Farmingham, Massachusetts/Sydney, Australia) reporting that the first U.S. patient has received its LVAS at Washington Hospital Center (Washington), marking the start of its U.S. trial (Medical Device Daily, Aug. 22, 2008). Similar to the DuraHeart, the impeller that spins inside the HeartWare LVAS pump is also suspended by magnetic forces. Although both pumps are much smaller than earlier generation devices, the HeartWare is actually small enough to fit directly adjacent to the heart in the pericardial space. Most other systems, including the DuraHeart, are implanted into a surgically-created pump pocket in the abdomen.
Other companies developing similar devices include Ventracor (Chatswood, Australia), Abiomed (Danvers, Massachusetts) and Thoratec (Pleasanton, California).
Earlier this year Terumo received the go-ahead from FDA to start its U.S. trial of DuraHeart as a bridge-to-transplant device (MDD, March 5, 2008). The company also reported a couple months ago that the Institutional Review Board of the University of Michigan Health System voted to move forward with the trial (MDD, June 30, 2008). The trial is expected to enroll 140 patients at up to 40 centers.
"We are extremely pleased with the performance of the DuraHeart and the recovery of our patient to an excellent functional state to permit discharge. We look forward to expanding upon our early experience with the DuraHeart in the near future," said Francis Pagani, MD, PhD, national co-principal investigator for the U.S. pivotal trial of the DuraHeart LVAS.
Terumo said the patient, a 62-year-old man from Livonia, Michigan, has been suffering from heart failure for nearly 20 years.
The goal of these devices is to return the patient back to a relatively normal lifestyle and to provide improved quality of life, Terumo said.
"We are delighted that the FDA has allowed us to begin this trial with no restriction on patient discharge, which has not been true of some of the other devices currently conducting trials in the U.S.," said Terumo Heart CEO Chisato Nojiri, MD, PhD.
In addition to the hocky puck-sized pump, the DuraHeart consists of the following components: an inflow conduit (a small titanium tube connecting the pump to the heart); an outflow conduit comprised of Vaskuteck Gelweave that is sewn to the aorta; a small battery-powered controller that serves as the brain of system and is worn or carried by the patient; and the hospital console, which allows doctors and hospital staff to monitor and have a degree of control over the pump.
Earlier-generation left ventricular assist devices (LVADs) are prone to hemolysis, blood clots and mechanical failure, Terumo noted. The company said it has tried to overcome these problems by combining the Mag-Lev technology and a centrifugal pump. The device has been used in more than 70 patients in Europe with the longest ongoing support more than three years. The device is intended to provide cardiac support for patients awaiting transplant who are at risk of death due to end-stage left ventricular failure.
Eventually, the company would like to get a "permanent" indication for the DuraHeart, in addition to the bridge-to-transplant indication. White said a trial for that indication is planned, but has not started yet. He said the permanent LVAS use market is much bigger than the bridge-to-transplant market because there are only about 2,000 donor hearts available and the criteria to receive a new heart is rather strict.