Spares have a big market

Imagine this in your future: During a commercial break, champion boxer and pitchman George Foreman looks out from the television, shakes his big fist, and proclaims, "You're not going to pay a lot for this . . . artificial heart."

While the day may never come that an artificial heart is marketed like a muffler, the day is fast approaching when aging baby boomers, like old cars, will increasingly demand spare parts to keep going. This demographic, which has driven economic trends for a half-century, is helping push the development of a wide range of devices to replace failing organs, spent tissue, and worn-out bones.

The potential market is huge: Tissue and organ failure already costs the US healthcare system about $500 billion a year, according to an estimate by researchers at the Massachusetts Institute of Technology, and that figure is expected to grow as America grows older. Synthetic hips and knees have been around for decades, but coming onto the market in the not too distant future may well be artificial hearts, veins, vertebrae, and livers.

For example, Abiomed Inc. of Danvers has already run human trials of battery-powered artificial hearts that patients can recharge by plugging into their car lighters. And who knows? A late night television commercial might someday pitch, "Uh-oh. Better get Abio."

With that, here's a look at what might become available in the parts department.

The pump

Scientists and engineers at Abiomed have been working for about 30 years to develop an artificial heart that would be powered by batteries and give patients the freedom of movement that makes life worth living. Now they're close to their goal.

Abiomed's artificial heart, the AbioCor, has been implanted successfully in nine people, keeping them alive for an average of nearly six months. By the end of the year, the company plans to seek approval from the Food and Drug Administration for humanitarian cases in which patients have no other alternative but an artificial heart. With that approval, as many as 4,000 people a year could have their lives extended by the AbioCor heart.

Abiomed has proved that its heart can run without mechanical failure for more than a year -- no small task, considering that its valves open 80 to 100 times a minute. Company officials say that two to three years of reliability are in sight and that five years and beyond are achievable.

To get to this point, Abiomed researchers have achieved several breakthroughs, including a power system that conducts electricity from the surface of the skin to the heart without implanting a wire, avoiding one pathway for infection. With current technology, the heart can operate one hour for each one-pound battery pack, which, with about $150 in modifications to a car, can be recharged from a car's lighter socket.

The pipes

Worldwide, about 500,000 people go through triple bypass operations each year because their blood vessels are so clogged that not enough blood can get to the heart. The procedure typically requires surgeons to remove a large vein from the leg, which is cut into three pieces and used to reroute the blood around the blockages.

CardioTech International Inc. of Woburn has developed a synthetic vein that company officials hope will spare bypass patients the sacrifice of leg veins. More important, it could also save the lives of about 100,000 people who, having had earlier bypasses, die each year because they no longer have veins large enough for the procedure.

The synthetic vein is made of specially developed polyurethane called chronoflex, which expands and contracts at the same rate as the natural arteries and is coated with a blood-thinning drug to prevent future clots, said Michael Szycher, the company founder.

The CardioTech vein is now undergoing clinical trials in Brazil, with company officials expecting to begin trials in Europe later this year and in the United States in 2005.

The filter

The liver is a dandy organ. It filters toxins from blood. It makes vital substances such as proteins. And, if healthy, it can regenerate itself: Cut off half, and a new one grows back.

This multitasking ability makes the liver difficult to replicate, but researchers at the Harvard-MIT Division of Health Sciences and Technology are combining synthetic materials and living cells to create an artificial liver. Eventually, researchers hope to develop a device that would be implanted in the body, but that goal still appears to be a long way off, said Dr. Mehmet Toner, a professor of biomedical engineering at Harvard Medical School.

In the meantime, they are closer to developing an external liver that would function much as kidney dialysis machines do. Such a device could be particularly effective in cases in which the liver shuts down after a sudden shock, such as a drug overdose.

In such cases, Toner said, the liver would eventually repair itself, but the patient often dies before that happens. The external device, however, could keep the patient alive while the liver heals.

Among the hurdles facing researchers is finding a method to preserve the cells while the device is on the shelf. One possible solution: a drying process that allows the cells to be rejuvenated by adding water, much as dried brine shrimp turn into so-called sea monkeys when dropped in water.

The support

The standard treatment for repairing aging, damaged vertebrae is to fuse the worn disc with a stronger one next to it. But Medtronic Sofamor Danek of Memphis, a unit of Minneapolis-based Medtronic Inc., believes that replacing the worn discs could give patients greater and more natural motion.

The company has developed three models of artificial discs, which have been approved by European regulators and are on the market there. Two are for the upper spine: One is all metal, and the other has plastic sandwiched between metal for cushioning. The third is for the lower back and is also all metal.

Michael DeMane, president of Medtronic Sofamor Danek, said the company hope to get the products approved and on the US market within the next three years.

In addition to the aging of the population, DeMane said another factor should help drive sales.

"Americans want to remain active," he said. "They're not comfortable with the idea of going home and reducing their activity for the rest of their lives."

Robert Gavin can be reached at rgavin@globe.com.