Twenty years ago, the world watched as Dr. William DeVries and a team at the University of Utah implanted an artificial heart into Seattle dentist Barney Clark. His own near-defunct heart was removed and replaced by the Jarvik-7, designed by Dr. Robert Jarvik. The bulky internal "heart" was connected to an aquarium-size machine that provided the external pumping action.
Clark lived 112 days.
In a field where change seems constant, basic factors have remained unchanged: People still die waiting for heart transplants, with the number of ill and fading hearts heavily outpacing the number of donor hearts available.
One company, ABIOMED, has been testing a fully implantable mechanical heart, called the AbioCor, as part of a clinical trial that has had mixed results. But most scientists and physicians today have pinned their hopes on ventricular-assist devices, or VADs, that help an ailing heart to pump, rather than replace it.
Jarvik has moved to New York, and his Jarvik 2000 ventricular-assist device is in clinical trials in the United States and Europe, where it is approved as an experimental device for long-term, even lifetime, use. In the United States, it's a "bridge" to a heart transplant, keeping patients alive who would have expired while on long waiting lists for donor hearts. Some of the earliest Jarvik 2000 patients, people in the end stages of heart failure, have been living with help from the device for more than a year, Jarvik said in a recent telephone interview.
The Jarvik 2000 is not a new concept. It's a second-generation ventricular-assist device, according to Karl Nelson, program administrator of the LDS Hospital Artificial Heart Program, joining a field that includes the DeBakey MicroMed and the HeartMate 2, which are both in clinical trials. The first generation, the HeartMate left-ventricular assist device (LVAD), is approved by the Food and Drug Administration as a bridge to transplants, and approval for permanent implantation seems imminent. The clinical trial, which included LDS Hospital, was completed months ago with results that were so positive the FDA has been asked to expedite the approval.
There are differences with all the devices. While the HeartMate looks a bit like a small canteen placed in the patient's abdomen, the Jarvik 2000 more closely resembles a C-cell flashlight battery. It's smaller and light. And it's implanted directly into the heart, then connected to an external controller and battery.
Like all the VADs, it's a booster pump augmenting whatever the heart can do on its own.
The Jarvik 2000 is being tested at the Texas Heart Institute and the Cleveland Clinic in the United States and at two centers in Sweden and one each in England, Germany and Switzerland. Soon, Jarvik said, they'll start a multi-center U.S. trial in hopes of getting approval for non-experimental use as a bridge and permanent heart-assist device.
Results of the trials, so far, he said, have been very good. The miniature rotary pump has been placed inside the left ventricle of nearly 40 patients worldwide.
The theory behind all of the devices is the same, Nelson said. "They're all pumps, designed to take over the work of a diseased and tired heart, providing quality of life."
The second-generation LVADs are smaller and vibration- and noise-free, Nelson said. "They should be easier to implant and lead to fewer complications, but the jury's out" until trials are completed. And just behind them, a third generation's already in the works, including one called HeartQuest that's being developed in Salt Lake City.
Within two years, scientists expect to be testing that generation, which all are magnetically levitated, without bearings, which should improve their longevity a great deal. Current LVADs last about two years before they're replaced; second-generation models promise up to about five years, and the third generation 10 years or more.
And there's a future already being mapped out beyond that, Nelson added. In 15 or 20 years, Nelson and others believe tissue engineering — biologically producing tissues to mend or replace the ailing human heart — will be done.
It sounds almost impossible. But no more so than today's LVADs would have appeared to the men laboring to put an artificial heart in Barney Clark's chest.
E-MAIL: lois@desnews.com