Medical Device Daily

Terumo Heart (Ann Arbor, Michigan) is one step closer in its quest to release its DuraHeart Left Ventricular Assist System on the market, after the Institutional Review Board of the University of Michigan voted to move forward with the device's pivotal trial for a bridge-to-transplant indication.

FDA gave unconditional approval for the trial in March (Medical Device Daily, March 5, 2008).

The DuraHeart LVAS Pivotal Trial is a multi-center, prospective, non-randomized study of 140 patients. It will include up to 40 centers and will last for 2-1/2 years, according to the company.

The DuraHeart LVAS is a third-generation circulatory support device intended to provide cardiac support for patients who are at risk of death due to end-stage left ventricular failure. An LVAS assists the left side of the heart in pumping blood throughout the body.

"Development of the device started in the mid-1990s," Marketing Manager Mark White told Medical Device Daily. "It works off the principle of centripetal force. The pump itself is shaped like a hockey puck. Fluid enters the center of the pump and flows out in a radial formation."

White said it is the only CE-marked implantable LVAS combining a centrifugal pump with magnetic levitation of the impeller, providing exceptional reliability and minimizing the potential for blood damage and thrombus.

"That's what makes the device unique – the magnetic levitation of the impeller – this allows the piece of the pump that does the work not to touch the cell. Typically when you use a pump to move blood there are a lot of issues to deal with. You just cannot have a device that ruptures cells."

Here's how it works.

The DuraHeart helps the left ventricle pump oxygenated blood throughout the body. Since a failing heart cannot pump enough blood to the body, the DuraHeart takes over the additional work.

With an implanted DuraHeart LVAS, blood flows from the left ventricle along two paths. Blood flows along its normal route, from the left ventricle directly to the body. At the same time, the DuraHeart Pump assists the heart by pushing blood from the bottom of the left ventricle to the aorta.

DuraHeart consists of seven main parts.

The primary component is the pump, which is implanted in the abdomen and is about the diameter of a hockey puck.

The Inflow conduit is a small titanium tube which connects the pump to the heart.

An outflow conduit comprised of Vaskuteck Gelweave is sewn to the aorta.

A small controller serves as the brain of DuraHeart and is worn or carried by the patient. It connects to the pump cable and is powered by batteries.

The batteries provide energy for the pump for a little more than three hours.

A battery charger provides power to the device and charges it while it remains inactive.

Finally, there is the hospital console, which allows doctors and hospital staff to monitor and have a degree of control over the pump.

The device is implanted in a preperitoneal pocket in the left upper abdomen. An apical cuff is sutured to the apical hole in the left ventricular apex with 12 mattress sutures of 3-0 Prolene pledgeted with Dacron felt. In the first six mattress sutures, the needle is exited from the apical hole after a full-thickness bite of myocardium, and in six additional mattress sutures, the needle is exited from the epicardial edge of the apical hole. Next, a double purse-string suture with 3-0 Prolene is placed on the Dacron pledgets around the apical hole. After the inflow conduit has been connected to the inlet port of the blood pump, the inflow conduit is secured to the apical cuff. The graft portion of the outflow conduit, which was connected to the blood pump beforehand, is sewn end-to-side to the ascending aorta with a 4-0 Prolene suture. Gentle suture connection of the apical cuff to the left ventricular apex and optimal alignment of the inflow conduit, which is bent by 60 , are crucial in the surgical procedure.

Ultimately Terumo Heart is looking toward getting a designation of permanent use for the device. To accomplish this designation the company plans to have another pivotal trial to be started about a year or so into the current bridge-to-transplant trial.

"We're going to have over 200 patients in (the permanent trial)," White said.

As to when the device might be available on the market with "permanent" labeling, he added that "designation is a little bit harder to peg" than the bridge-to-transplant indication.

Terumo Heart is a business unit of Terumo Medical (Somerset, New Jersey) and develops cardiovascular devices.