The High-Tech Heart: The Artificial Heart
Articles about the artificial heart made headlines last summer, but often lost in the headlines was the fact that the artificial heart is a highly experimental procedure. It's part of a clinical trial conducted under what's called an "Investigational Device Exemption" from the United States Food and Drug Administration.
The device that's been used is called the AbioCor Implantable Replacement Heart. A company called Abiomed, Inc., based in Danvers, Massachusetts, produces it. The company claims that the AbioCor is "intended to extend and improve the lives of patients with irreversible end-stage heart failure."
Who's a Candidate for AbioCor?
According to the Abiomed Web site, patients accepted into the clinical trial must
- Suffer from otherwise untreatable bi-ventricular heart failure (heart failure that affects both ventricles)
- Not be eligible for a heart transplant
- Have a high probability of dying within 30 days
The first heart was implanted last summer, on July 2nd, at Jewish Hospital in Louisville, Kentucky. Initially, the hospital did not reveal the patient's name, but by late summer he was identified as Robert Tools. He did well for several months, even leaving the hospital on a few occasions. In mid-November, he suffered a setback. He had a stroke, which is one of the expected complications of the artificial heart. In late November, he died of severe abdominal bleeding.
As of mid-January, six patients have received the mechanical heart. Three of those have died. One patient did not survive the surgery, one died of multiple organ failure and the other death was Robert Tools.
These statistics may sound grim to the layperson, but Abiomed, Inc. believes that the results have been positive. They stress that having the surgery improved patients' quality of life and doubled their life expectancy. Remember that patients who receive the device must have a high probability of dying within 30 days. They basically have no hope left.
How the AbioCor Works
The AbioCor is designed to circulate blood through the body in the same way that the natural heart does. The device is made of titanium and plastic. It weighs about two pounds, and runs on an internal battery that is continually recharged by an external battery that patients wear around their waist. Basically, the AbioCor simulates the natural heartbeat.
The device gives patients some freedom of movement. They're not tied to large machines, the way they were with the first artificial heart in the early 1980s. And the risk of infection is lower than it was with the older hearts, because the external battery that patients wear is not connected to the heart internally. But the risk of infection in general is still there with the AbioCor.
The AbioCor is an alternative to heart transplant, which is currently the only treatment option left for patients who don't respond to other treatment for heart failure. Hundreds of thousands of people are on a waiting list for a heart transplant, but only about 2,000 people in the U.S. receive donor hearts each year.
What are the Risks?
Blood clots (which increase the risk of stroke) and infection are the greatest risk for AbioCor recipients. Patients who receive the AbioCor routinely take anticoagulant medications (blood thinners). Robert Tools, the first recipient, was unable to tolerate anticoagulants. He initially took them, but bled from the nose and abdomen.
Not Yet an Option for Most
If there ever comes a time when the artificial heart is ready to be implanted in a large number of patients, that time is far off. With each new recipient, doctors and researchers learn more about fine-tuning the device to make it safer for the many patients who are on a waiting list for heart transplants. Until that time, it's still highly experimental and limited to those few patients who qualify for the clinical trial.
For now, the best way to ward off heart failure is prevention. Mechanical hearts may become a common treatment sometime in the future, but for now, eating the right foods, getting exercise, managing stress and getting regular heart checks are better ways to fight heart failure.
The Abiomed Web Site; The New York Times, 20 November 2001;