Maybe this is what the future looks like. There's a bland industrial park on the outskirts of Boston, with a room full of bright lights and white linoleum. Dozens of small steel tanks are stacked in neat rows. Step up to any one of them, press your face to the circular window and there it is: a human heart, made entirely of titanium, plastic and epoxy, and beating as incessantly as your own. These organs have pumped away day and night for the past year while instruments gauge their fluid pressure and flow rate. They are only test models. But within the next few weeks, doctors will place identical devices in the chests of five critically ill patients, making them the first humans ever to receive completely self-contained artificial hearts. Officials at Abiomed, the company behind this technology, are wary of raising expectations. But as chief scientific officer Robert Kung says, "This opens a new chapter in cardiac medicine."
Will it be a happy one? Technology has revolutionized coronary care in recent decades, and countless patients have benefited. Physicians can now remodel a child's defective heart by manipulating tiny instruments through catheters. Surgically implanted devices can quintuple the heart's output when it falters, or regulate its contractions when they become dangerously erratic. But no one has yet designed a machine that can permanently replace this miraculous muscle. The most famous attempt--involving a heart called the Jarvik-7 and a patient named Barney Clark--was such a public-relations debacle that it set back research by nearly a decade. The Jarvik-7 required a power console as big as a washing machine, and the wires connecting the device to the console created an open channel for infection. Clark endured a slow and torturous death, but engineers and surgeons learned valuable lessons from his experience and that of subsequent volunteers. A refined Jarvik-7 is still used occasionally, but only as a bridge to sustain patients briefly while they await transplants.
Abiomed's new heart is a far sleeker appliance. Instead of a 350-pound power console, the AbioCor runs off a battery the size of a VCR tape. Through an external coil on the patient's midriff, the battery powers a surgically implanted system that feeds electricity to the heart. To recharge the battery, patients will simply plug it into an AC outlet. The AbioCor has performed well in calves, and lab tests suggest that critical components could last at least five years (roughly 180 million beats) in ailing people. Unfortunately, the first recipients have little hope of living that long. "Every one of these first five patients is likely to die on the AbioCor," says David Lederman, Abiomed's president and chief executive officer. All five have advanced heart failure and life expectancies of a month or less. If the device can sustain them for two months without extreme side effects, the Food and Drug Administration will likely authorize larger trials with healthier subjects. And if those larger studies show that patients receiving AbioCor consistently outlive those on medication, the FDA will presumably clear it for marketing. No one expects that to happen for several years.
The need is undeniable. Every year, congestive heart failure contributes to about 300,000 deaths in the United States--nearly twice as many as stroke and seven times as many as breast cancer. The causes of heart failure are varied, ranging from alcoholism to arteriosclerosis, but the effects are never pretty. As the damaged heart muscle loses its pumping ability, the smallest physical task becomes a colossal effort. Sores form on the sufferer's unnourished skin, and stagnant fluids build up throughout the body. Eventually, says Dr. Jack Copeland of the University of Arizona Heart Center, "patients are literally drowning." That's how 57-year-old Art Kastner felt four years ago, when a nick on his ankle spawned an infection that traveled through his bloodstream and damaged his heart. "They had to put me on dialysis almost every day to get the fluid out," he recalls. "At one point they took out 61 pounds of fluid in two weeks."
Hearts this sick don't get better, but patients who receive transplants sometimes do. Kastner joined a waiting list in March 2000 and, six months later, inherited the heart of a healthy 17-year-old accident victim. He now requires 30 pills a day to maintain his new organ, but he is off dialysis, working five days a week and planning a future. The trouble is, only 2,000 of the 70,000 Americans who might benefit from a heart transplant get one in any given year. Medication can make life more bearable for the others, in part by helping them eliminate fluid. But the drugs have little impact on survival in advanced patients.
Until now, the next best thing to a transplant has been a "piggyback heart"--a small, implantable machine that augments the failing heart's pumping capacity while the patient awaits a new organ. Known technically as VADs, or ventricular assist devices, these implants can sometimes rescue even the most desperate patients. Just ask Peter Houghton. Last June, the 62-year-old English psychotherapist was within days of death. His heart's output had fallen to 10 percent of normal, leaving him bloated and too weak to breathe. Then a physician at Oxford University offered to include him in a test of a new piggyback device--an "axial flow pump" that pushes blood in a continuous stream (no pulse) through the heart's left ventricle and out into the body. Houghton suffered complications from surgery, and spent three months in what he calls "intense agony." But he started feeling human after four months, and was soon back to hiking, traveling, socializing and even working part-time. Last week he completed a 91-mile charity walk for England's Artificial Heart Fund.
Worldwide, some 10,000 patients have received different VADs since 1994, and many have resumed active lives. But these machines are still stopgaps, not solutions. Though portable, the approved models all have power lines that protrude through the skin, causing infection in at least 20 percent of patients. And because VADs assume only part of the heart's workload, some patients continue to deteriorate. Basil Tershakovec of Millburn, N.J., survived on a VAD for several months after his heart failed last year--but the device couldn't keep blood from washing backward into his flaccid ventricles. Tershakovec's doctor discovered the problem during an examination in February, and promptly admitted him to New York's Columbia-Presbyterian Hospital to wait for a donor organ. Like Kastner, he won that lottery and now has a 38-year-old heart beating in his 62-year-old chest.
An artificial heart that was portable and wireless would offer obvious advantages. Unlike a donor organ, it would be availa- ble on demand and wouldn't require a lifetime of antirejection therapy. And unlike today's VADs, it would give patients permanent relief without causing life-threatening infections. AbioCor may not accomplish all that, but it represents a huge leap forward. The device incorporates hundreds of separate advances, from valves that make no clicking sound to pumping chambers too smooth to foster blood clots. And though it lacks the pumping capacity a basketball player would need, it will adjust its own output as needed to accommodate low-key hiking or gardening or sex. Dr. Laman Gray Jr. of the University of Louisville calls it "the most complex medical device ever made."
Like a natural heart, the AbioCor has two ventricles, or pumping chambers--one that sends blood to the lungs to pick up oxygen, and one for pushing freshly oxygenated blood out to the rest of the body. But its mechanics are different from those of a living organ. Sandwiched between the two chambers is a small device that hits their soft walls with jets of fluid, compressing them in quick succession and forcing their contents into the attached arteries. When it's idling, the device pumps the same volume of blood as a resting heart (roughly five liters per minute). But when an increase in muscle activity raises the pressure in the ventricles, the engine speeds up accordingly. AbioCor's peak capacity is 10 liters per minute (hence sex instead of basketball), but users won't have to worry about overtaxing it. Unlike a natural heart, it won't try to adapt to extreme demands. It will limit the patient's ability to make them.
While this heart may make life possible for some people, it won't make life simple. Implanting the system will require open-heart surgery, plus a series of incisions to install other components of the system. In addition to the pump itself, the patient's torso will house a power coil (to take in electricity), a controller (to distribute it) and a backup battery (to power the pump for 30-minute intervals while the external batteries are removed).
Once the patient recovers, the system will still demand constant attention. Batteries will have to be recharged or replaced every four hours, and an externally worn monitor will squeal obnoxious warnings whenever the batteries run low. Living off a battery pack beats living off a 350-pound crate, but as many VAD users have discovered, it's a constant source of stress. Houghton, the English therapist, once mistakenly placed a half-spent battery in his assist device just before traveling a half hour for a dental appointment. The alarm went off while his dentist was placing a crown, and Houghton had to race home for a battery, hoping a traffic delay wouldn't shut down his heart.
These are the easy problems, the ones that will crop up when the machine is working perfectly. There will surely be others. A healthy human heart beats about 100,000 times a day, or 35 million times a year, and it performs without glitches or downtime or part replacements. Toasters and televisions don't work that way, and it's hard to imagine that an implantable heart will, either. To spot likely problems in advance, Abiomed's engineers have tested some parts of the AbioCor system for the equivalent of 37 years (they speed up the beats to compress time). And they plan to establish a 24-hour troubleshooting center that can receive information directly from patients' devices. Still, if the AbioCor goes into wide use, absurd accidents are sure to happen. Once while Houghton was shopping, a thief snatched the bag that carries his battery and monitor. Fortunately the alarm on the monitor startled the thief into dropping his booty, and Houghton managed to plug himself back in.
Cardiac gadgets may some- day sing like mobile phones from every purse and pocket, but some experts believe simpler ones will prevail over AbioCor. Total heart replacement is a naive, space-age concept, they say, like flying cars or meals in a pill. The skeptics predict that when patients can choose between two permanent, wireless devices--one designed to replace the heart and one meant to assist it--most will want to keep what's left of their own failing hearts. Several companies are now developing VADs that lack percutaneous wires, and the devices themselves are getting smaller and easier to implant. This is especially true of "axial flow" devices like Houghton's. They're not only simpler and quieter than pulsating machines, but easier to remove if a donor heart comes along.
Patients may soon have other options as well. Hearts from genetically modified pigs are one possibility, although critics worry about rejection and disease transmission. And tissue engineers are racing to grow viable heart muscle in test tubes. In the end, all these approaches may prove useful. "Heart failure is a spectrum of disorders, and we'll want a spectrum of ways to treat it," says Dr. Adrian Kantrowitz, an early developer of cardiac-support devices.
One question dogging all these new technologies is cost. At the outset, the AbioCor will run approximately $75,000, excluding the cost of the surgery and follow-up. Skeptics question whether a brief respite from a fatal condition justifies such cost. But the last year of treatment for patients in heart failure is always expensive, with hospitalization running at about $90,000 a month. "There was a similar argument made about pacemakers and implantable defibrillators when they came out," says John Watson, director of clinical and molecular medicine at the National Heart, Lung, and Blood Institute. "Today, economists say they save the system money by reducing hospital admissions." Abiomed's Lederman predicts that AbioCor's price will eventually fall to about $25,000. If the device gives people five years of health and mobility, no one is likely to complain. A heart transplant costs 10 times that amount.
Valerie Latimer-Axelson has spent the past year and a half waiting for a donor heart. Axelson was born with a congenital heart defect 23 years ago, and spent her childhood in and out of hospitals. She emerged with a still-failing heart, and a spirit as tough as her native Texas. Her doctors told her to expect a two-year wait when she joined the transplant registry, but they're now saying it could be more like three. Will she consider the AbioCor if she still needs a heart when it reaches the market? "Sure, I'll consider it," she says with a laugh. "I've always been a guinea pig." But Axelson has a backup plan. "If four or five years pass and I find myself still waiting, I'll take myself off the list and live a normal life to the best of my ability," she says. "Because when you're on the transplant list, you tend to center your whole life around it." If a donor doesn't liberate her, technology just might.THE QUEST FOR AN ARTIFICIAL HEARTFOR ALMOST HALF A CENTURY, PHYSICIANS, SCIENTISTS AND ENGINEERS HAVE WORKED ON WAYS TO HELP THE AILING HEART--OR REPLACE IT ALTOGETHER.
1953: Dr. John Gibbon shows that a mechanical device can temporarily replace heart function when doctors use his new heart-lung machine in successful open-heart surgery
1964: The U.S. government launches the National Heart Initiative, aiming to have a total artificial heart by Valentine's Day 1970
1967: Dr. Christiaan Barnard in South Africa performs the first human heart transplant. The patient dies 18 days later, of pneumonia.
1969: Dr. Denton Cooley of the Texas Heart Institute implants the poorly tested Liotta heart into patient Haskell Karp, who dies within five days. The Liotta is never used again.
1982: Exactly 15 years after the first heart transplant, Dr. William DeVries implants the Jarvik-7 (named after Dr. Robert Jarvik) into Seattle dentist Barney Clark. Clark survives for 112 days.
1994: The FDA approves the HeartMate IP, a 'piggyback' device that assists the failing heart without replacing it. The air-driven pump requires a large external power console.
1998: The first portable assist devices reach the market
2000: Dr. O. H. Frazier implants the first Jarvik 2000, an assist device that generates continuous blood flow rather than pulse.
2001: AbioCor, the first fully implantable artificial heart, will be tested in humans