The Temple team, headed by Dr. Jacob Kolff, chief of cardiothoracic surgery, has spent more than five years and $1 million developing the polyurethane heart and the mechanical unit that powers it. After testing the device on more than 25 calves in Utah, they are cautiously optimistic that the federal government will approve its use in people.
Neither Temple researchers nor the federal Food and Drug Administration, which has been reviewing Temple's proposal since February 1986, will speculate on when - or even if - approval will come. But an industry source said that if all goes well, the FDA could approve its use in humans within a year - and possibly by the end of 1988.
If, and when, the government says yes, Kolff - who has performed numerous heart transplants at Temple University Hospital - is prepared to implant the artificial heart into the chest of a human patient. Because of the public's interest in heart disease, the nation's leading killer, such a development is likely to thrust the "Philadelphia heart" into newspaper headlines and perhaps into the nation's consciousness.
Kolff, whose father, Willem, developed the first artificial heart at the University of Utah, cautioned that the Philadelphia heart is designed to be a temporary medical device. It is designed to be a "bridge-to-transplant" artificial heart, meaning that it would remain in the patient two to 10 days, until a real heart can be found.
"Our heart is a last-ditch stand," said Kolff last week. "It's not meant to be permanent."
Such a device is important because an estimated 15,000 to 25,000 people a year are in need of transplanted human hearts. But since only about 1,500 to
2,000 hearts are available annually, there is a strong need for a temporary artificial heart that can be used until a real heart can be found.
The Philadelphia researchers say their heart has several advantages over the Jarvik-7 heart, which has been used in most of the more than 130 artificial heart operations performed since Dec. 1, 1982, when the first was permanently implanted into Barney Clark, a retired dentist.
First, and most important, they believe the Philadelphia heart will be safer. All five of the patients given the Jarvik-7 heart as a permanent replacement died within two years, either of a stroke or of infection caused by the implant. Among the other problems reported in heart patients who have received the Jarvik-7 are blood clots, excessive bleeding, kidney failure, fever and seizures.
David Wurzel, vice president of operations at Cardiac Systems Inc., a Conshohocken firm set up to manufacture the Philadelphia heart, said that in animal tests conducted on calves in Utah, the animals had experienced far fewer blood clots than with the Jarvik-7. This is important because clots can travel to the brain, causing strokes.
Wurzel said the Philadelphia researchers had increased the safety of the art by developing a new way to attach the heart to the patient's blood vessels. By using sleeves that are sewn to the vessels, they create a smoother surface than exists in the Jarvik-7, which has a joint where clots can form.
The Philadelphia heart will also be less expensive, the researchers say. Wurzel said the Temple team had tried to use "mass-produced, off-the-shelf equipment" whenever possible to keep the costs down. They are also using a manufacturing technique, known as "vacuum forming," that can produce the disposable hearts more quickly and less expensively than the Jarvik-7 heart.
The Philadelphia heart consists of two ventricles, or the lower chambers of the heart; four valves, and an air-powered driver, known as "Philadrive," that causes the heart to beat.
The ventricles and valves of the Philadelphia heart cost about $13,500 - or about two-thirds the $20,000 price tag of the Jarvik-7, Wurzel said. In future designs, the cost of the ventricles and valves could decline to less than $2,000, he said, as less expensive components are used.
Similarly, the cost to start up a medical center at a hospital using the Philadelphia heart system will be less than half of what it costs to set up a center for the Jarvik-7, the researchers said, in part because of the training and inventory involved. Wurzel estimated that such a center would cost about $185,000 for the Philadelphia heart, compared with the $425,000 needed for the Jarvik-7.
A third advantage of the Philadelphia heart is its smaller size, which makes it more suitable for women than the larger Jarvik-7. The Philadelphia heart looks like a flattened sphere about three inches in diameter; the Jarvik-7 is more spherical and slightly larger. Wurzel said that the vacuum- manufacturing technique they are using would make it easier for them to make both smaller and larger sizes in the years to come.
Missfeldt said that the Philadelphia team hopes to begin work on the next generation of its artificial heart beginning next year. Unlike the present version, in which the patient will be tethered by tubes to a "heart cart" carrying the air-powered driver, the next generation would give the patient much greater mobility. Its drive system would be portable and able to fit inside a shoulder bag.
Wurzel said that eventually Cardiac Systems hopes to sell a wide variety of models, ranging in size from those suitable for children to those for 250- pound men and including both temporary and permanent hearts. But he said that an artificial heart that can be permanently implanted is "at least 10 years down the road."
Because the Philadelphia heart has been developed with private funds, Wurzel said that changes in federal funding for artificial heart development should not affect their efforts. The Temple team has received money from Temple University, the Benjamin Franklin Partnership Program and private investors.
In May, the National Institutes of Health announced that it was abandoning its effort to develop a totally artificial heart and would instead concentrate its funds on smaller, less complex pumps that assist rather than replace ailing hearts. Since 1964, the federal government has spent about $240 million to develop artificial hearts.
But in July, bowing to political pressure by Sens. Orrin G. Hatch (R., Utah) and Edward M. Kennedy (D., Mass.), the National Institutes of Health reversed itself and said such efforts would continue. Among the institutions that had its funding restored was the Hershey Medical Center in Hershey, where another version of the artificial heart has been developed.
As artificial hearts are developed and improved, they will undoubtedly extend the lives of many. But most researchers say it is unlikely that they will eliminate the need for human hearts to be transplanted.
Patricia Kolff, the wife of Jacob Kolff, said that about 900 people are waiting for a heart transplant every day. "About 300 people a year die waiting for a heart that never comes," she said. "The clock just runs out on them."
Kolff, who is the national executive director of the National Heart Assist and Transplant Fund, a non-profit group, urged people to donate their hearts to help the tens of thousands of people who could benefit from heart transplants each year.
People can legally arrange to donate their hearts by filling out a donor card that can be obtained by writing to the fund at 519 W. Lancaster Ave., Haverford, Pa. 19041. The fund also assists people in raising money for heart and lung transplant operations.
"The families who have donated the organs of their loved ones have received tremendous strength knowing that they have saved someone else," said Kolff. "It can help make a very sad time into a positive experience."