Sunday 27th May 2007
An investigational cardiac device by the name of VentrAssist ?? Left Ventricular Assist System (LVAD) is currently being tested by doctors at the University of Pittsburgh School of Medicine to examine its efficacy and safety in patients with end-stage heart failure.
More than 5 million Americans currently live with heart disease with 550,000 new patients being diagnosed each year. While resources for treatment of heart disease are significant, the overall outcomes remain poor. According to estimates from the American Heart Association, individuals diagnosed with heart failure have less than 50% survival rate over a five year period. The one-year survival rate in end-stage heart failure patients is even worse and estimated to be as low as 25% regardless of medical therapy.
The VentrAssist LVAD is a mechanical blood pump. When implanted in the body for people with end-stage heart failure, it helps the heart pump blood around the body. The pump is made of titanium and weighs just over half a pound. This makes it much lighter compared to older pumps weighing around five pounds.
The VentrAssist pump is connected to the heart and the aorta by two tubes called cannulae. This allows it to draw blood directly from the left ventricle and return it to the aorta. An external controller regulates the pump which works in coordination with the natural beat of the heart.
What distinguishes the VentrAssist LVAD from other cardiac assist devices is its centrifugal design, which allows it to operate in a manner that responds to exercise very similarly to the natural heart. Still in an experimental investigational stage, VentrAssist LVAD has been approved by the FDA only for study purposes.
Doctors at UPMC are hoping to enroll 30 patients for their multi-center feasibility study that is to be conducted simultaneously at nine centers across the US. Five patients at UPMC have already received the VentrAssist LVAD. One of these patients has successfully received a heart transplant after being on the pump for nearly three months. Two of these months were spent at home on the device.
??The VentrAssist LVAD presents us with a third-generation mechanical solution for end-stage congestive heart failure that approaches the goal of minimal interference with a patient??s life. In a subsequent study with this pump, we will focus on support for transplant candidates as well as permanent use for those who do not qualify for heart transplantation, hopefully demonstrating its advantages over previous technology,? said Robert Kormas, Medical Director of the McGowan Institute for Regenerative Medicine and Professor of Surgery, Division of Cardiothoracic Surgery at the University of Pittsburgh School of Medicine.
The number of LVADs that are commercially approved for bridge to heart transplant are limited at present. While earlier models have benefited some patients, the large size of the devices make them cumbersome.
The patients need to be tethered to machines, which severely limits their activity. With the VentrAssist LVAD study, researchers hope they might be able to find a way to reduce the load on the patient??s heart and improve blood flow and circulation without really affecting the overall quality of life.
Some patients who had been transplanted with earlier model LVADs had recovered their own heart which allowed them to be weaned off the LVAD with the need for a heart transplant. While it is not yet known if the VentrAssist LVAD will also have the same effect, a parallel US clinical trial will look at the safety and feasibility of the VentrAssist LVAD as an alternative to transplantation.
