The first full-support, miniaturized ventricular assist device designed to be placed in the pericardial space, was approved by the FDA in late November. HeartWare International, Inc., Framingham, MA, an innovator of less invasive, miniaturized circulatory support technologies to treat advanced heart failure, said that its Ventricular Assist System was approved as a bridge to cardiac transplantation in patients who are at risk of death from refractory end-stage left ventricular heart failure.
The device features a small implantable centrifugal blood pump called the HVAD®, a full-output circulatory support device designed to be implanted next to the heart, avoiding more-invasive abdominal surgery generally required to implant competing devices. Implanting the device above the diaphragm should lead to relatively short surgery time and quicker recovery for patients in late-stage heart failure. The pump is designed to draw blood from the left ventricle and propel it through an outflow graft connected to the patient’s ascending aorta, and can generate up to 10 liters of blood flow per minute.
The HVAD pump has only one moving part, an impeller, which spins at rates between 2,400 and 3,200 revolutions per minute. The impeller is suspended within the pump housing through a combination of passive magnets and hydrodynamic thrust bearings. Hydrodynamic suspension is achieved by a gentle incline on the upper surfaces of the impeller blades. When the impeller spins, blood flows across the inclined surfaces, creating a “cushion” between the impeller and the pump housing. There are no mechanical bearings or any points of contact between the impeller and the pump housing. The HVAD pump, with sintered inflow cannula, weighs approximately five ounces and displaces a volume of approximately 50 milliliters.
The company’s pre-market approval (PMA) submission included data from its pivotal ADVANCE clinical trial, an FDA approved Investigational Device Exemption study designed to evaluate the device as a bridge to heart transplantation for patients with end-stage heart failure. Under ADVANCE, 140 patients at 30 hospitals in the US received the investigational device between August 2008 and February 2010. The study achieved a 94% survival at six months and successfully met its primary endpoint of establishing non-inferiority between the investigational device and comparator arm of the study, which was derived from contemporaneous patients from the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS). Four supplemental allotments of patients were granted by the FDA under a Continued Access Protocol, encompassing more than 250 additional patients.
“I’ve had the opportunity to work on the HVAD® project since its conception over a decade ago. The goal was to develop a miniaturized device with an integrated inflow cannula that could be placed within the pericardial sac, avoiding the necessity of creating a pump pocket with its attendant infection risks, as well as simplifying the surgical insertion,” said O.H. “Bud” Frazier, MD; Chief, Center for Cardiac Support; Director, Cardiovascular Surgery Re search; and Co-Director, Cullen Cardiovascular Re search Laboratories, at Texas Heart Institute and a global pioneer in mechanical circulatory support.
To help assure the continued safety and effectiveness of an approved device, the FDA requires a post-approval study (PAS) as a condition of approval under 21 CFR 814.82(a)(2) to assess the device’s performance in a real-world setting. HeartWare’s PAS registry consists of 600 patients who receive an HVAD and an additional 600 control patients derived from a contemporaneous group of continuous flow, intra-corporeal LVAD patients entered into the INTERMACS database. INTERMACS is a North American registry established in 2005 for patients who are receiving mechanical circulatory support device therapy to treat advanced heart failure. The data for both parts of the study will be entered into the INTERMACS registry by the implanting centers.
In other clinical development for the HeartWare Ventricular Assist System, HeartWare has completed enrollment of a 450- patient destination therapy study at 50 US sites. The final patients were implanted in May 2012, with a two-year, primary endpoint follow-up period. HeartWare has requested a Continued Access Protocol allocation for destination therapy from the FDA.
Although just approved for sale in the US, the technology is the leading ventricular assist device implanted in patients outside of the United States, having received CE Marking in the European Union in 2009, and Australian Therapeutic Goods Admini stration approval in 2011. It has been used to treat patients in 27 international countries and more than 2,500 advanced heart failure patients globally have received the HVAD® pump.
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