Overview of Three Ventricular Assist Devices
Thoratec, Pleasanton, CA
FDA approval: Thoratec received approval from the Washington, DC-based Food and Drug Administration (FDA) for its ventricular assist device (VAD) system to be used as a postcardiotomy recovery system in May 1998. The company previously received approval for the device’s use as a bridge to transplant.
Number of patients: As of June 1999, the Thoratec VAD had been implanted in more than 1,000 patients worldwide.
Features and operation: The Thoratec VAD is the only currently available system that offers total circulatory support and can be used as a left, right, or biventricular support device. The VAD is driven by a lightweight, portable driver that allows patients to leave the hospital while awaiting a heart transplant. The device is made of Thoralon, a patented, thromboresistant and biocompatible material, which greatly reduces the risk of blood clots.
Thermo Cardiosystems, Woburn, MA
FDA approval: In 1994, Thermo Cardiosystems received FDA approval for its air-driven Heart Mate left ventricular assist device (LVAS). The company received FDA approval for its electric Heart Mate LVAS system in 1998. Both of those systems are approved as a bridge to transplant.
Number of patients: To date, more than 1,500 patients have been supported by a Heart Mate system worldwide.
Features and operation: The Thermo Cardiosystems devices are designed to assist the left ventricle, or main pumping chamber of the natural heart, only. The central component of the LVAS, the implantable blood pump, is placed just below the diaphragm in the abdomen. It is attached between the natural heart and the aorta, leaving natural circulation in place while providing all of the energy necessary to propel blood through the body.
The air-driven pump weighs just over 1 lb. The electric pump weighs about 2½ lbs. Both devices are roughly four inches in diameter and less than two inches in depth. Both the air-driven and the electric devices use a proprietary Heart Mate blood pump technology, which includes a uniquely textured surface designed to reduce the risk of stroke.
The air-driven model is powered by a lightweight external console, about the size of a VCR, which patients can move about on a wheeled cart. The electric Heart Mate has a beeper-size control pack and is powered by lightweight batteries that can be worn in a shoulder holster or waist pack. Patients with the electric model typically return to their normal routines, including their jobs.
Web: www.thermocardiosystems. com t
Baxter Healthcare, Cardio vascular Group, Oakland, CA
FDA approval: Baxter received FDA approval for its Novacor Left Ventric ular Assist System as a bridge to transplant device in September 1998.
Number of patients: Nearly 900 patients worldwide have received a Novacor LVAS. Two have been supported for more than three years by their original devices.
Features and operation: The Novacor LVAS is an electro-mech anical heart pump that is implanted in the abdomen and connected to the heart’s left ventricle. The system is operated by an external, portable electronic controller and is powered by battery packs, which a patient typically wears around the waist or in a shoulder vest or backpack.
The controller and batteries are connected to the pump by a per cutaneous lead through the skin. The system is self-regulating and responds instantly to changes in heartbeat and circulatory demands. Many recipients can be discharged from the hospital to resume normal activities and return to work.