P&S Journal: Spring 1996, Vol.16, No.2
A Boost for Heart Failure Patients
Congestive heart failure is a devastating condition that affects an estimated 3 million people in the United States, and it is on the rise. P&S researchers, in collaboration with ABIOMED, a Massachusetts-based company, are developing a device they expect will improve quality of life for many of those who suffer with heart failure. The investigators have been awarded a five-year, $4.35 million contract from the National Heart, Lung and Blood Institute to develop a heart support system temporarily called the "heart booster."
Heart failure is the most common reason Americans over age 65 are hospitalized. When the heart begins to fail it is no longer able to pump an adequate supply of blood and meet the metabolic needs of body tissue. For many patients this condition can be treated adequately with drugs, such as angiotensin converting enzyme inhibitors or beta-blockers. In the most severe cases, when death is likely within one year, more aggressive treatment is indicated to assist the heart in pumping blood. Left ventricular assist devices (LVADs) and artificial hearts (TAHs) are often implanted in these patients as a temporary bridge to heart transplantation.
There also are patients who do not face imminent death but for whom drug therapy is not sufficient. These patients have a poor quality of life, are debilitated, and are often confined to a bed or chair. Because their condition is not life-threatening, the risks associated with implanting an LVAD or TAH-such as infection and thrombosis-or performing a heart transplant are not justified. It is this group of patients the investigators expect to help with the heart booster.
"This device is targeted at the increasingly large population of patients with moderate to severe congestive heart failure," says Dr. Eric A. Rose, co-principal investigator and chairman of surgery. "What is needed in these patients is a device that poses sufficiently low risk, that doesn't contact flowing blood, and will squeeze the heart gently in the proper rhythm to increase blood flow," says Dr. David M. Lederman, president and CEO of ABIOMED.
The heart booster device will be constructed of plastic and will wrap around the heart; an incorporated pacing system will cause it to squeeze the heart to augment the heart's natural beating activity. No device surface will be in direct contact with blood, which will result in reduced risk for thrombosis. The final design will be fully implantable in the body, decreasing the risk of infection, and will fit a wide range of sizes of adult men and women. Dr. Lederman calls it "the mechanical equivalent of a pacemaker." A pacemaker normalizes electromechanical pacing between the atria and the ventricles but does not directly impact mechanical pumping capacity. This device will actually "boost" the pumping capability of damaged ventricles on a beat-per-beat basis. It also will be designed to provide selective degrees of assistance according to the needs of the left or right ventricle.
In addition to increasing the heart's ability to deliver blood to the body, the booster is expected to stop the deterioration that may occur in many cases of congestive heart failure, thereby reducing the number of patients who progress to the severe stages of the disease. "A heart booster device would allow people with lifestyle restrictions to lead normal and productive lives," says Dr. Robert T.V. Kung, principal investigator for ABIOMED. "When you have heart problems, there are many things you can't do. Even carrying a briefcase can be difficult."
The exact design of the device and the pacing technology are under development. "The purpose of the contract from NHLBI is to give us time to test different designs," says Dr. Rose. "We are confident that in five years we can devise a very credible device."
ABIOMED is providing technological expertise in the development of the device and will work in close collaboration with researchers who will assist with the design and perform pre-clinical and, ultimately, clinical trials. Columbia boasts the largest heart transplant program in the country and one of the world's finest centers for the treatment of heart failure.
|This illustration of ABIOMED's Booster-Heart shows the anatomical implant locations of the system components.|