Stimulus for an Ailing Heart

By Jamie Murphy.

Mary Jones, 46, knew she was in trouble early last year. "I was having problems going up the stairs," she remembers. "I would go up halfway and then stop and rest for a while or crawl up the rest of the way. Sometimes, just talking, I would be gasping for breath." So the Pittsburgh mother of two, whose history of coronary ailments includes two heart attacks, checked into the city's Allegheny General Hospital to have a bubble, or aneurysm, in her heart's left pumping chamber surgically excised and the tissue repaired.

The removal of a substantial part of the heart can severely restrict a patient's activities. In extreme cases, the organ's pumping action can be reduced by as much as 60%. To avoid these debilitating consequences, Jones' surgeon, George Magovern, wanted to try something new: bolstering her weakened heart with a muscle transplanted from her back.

During the five-hour procedure, an Allegheny plastic surgeon detached a latissimus dorsi--a broad muscle that plays a nonessential role in controlling arm motion--from its connection points along the spine. Magovern slipped it into the chest cavity with the muscle's nerve system and major blood supply intact, then wrapped it around Jones' heart like a towel. After a week's recovery time, he began stimulating the transplanted skeletal muscle with a pacemaker, causing it to contract and help pump blood. Less than a year later, Jones reports that she can walk a mile or two without difficulty and even play basketball with her daughter.

The procedure was remarkable mainly because skeletal muscle and cardiac muscle are structurally different. Heart muscle works continuously, using oxygen at a steady rate. It never tires. Skeletal muscle is designed for short bursts of intense effort and fatigues easily. Ten years ago, while operating on a patient whose pacemaker had slipped out of place, Magovern made a chance observation. The patient's chest muscle, stimulated by the misplaced device, had doubled in size and showed no signs of fatigue. Other researchers independently proved that skeletal muscles actually come to resemble their cardiac counterparts when electrically conditioned.

Jones is not the only beneficiary of such research. Paris Surgeon Alain Carpentier last year used a pacemaker-trained back muscle to patch a hole left in the heart of a 35-year-old woman after removal of a tumor. The woman has fully recovered. Says Carpentier: "It's exciting to see how flexible nature is."

At the University of Pennsylvania Medical School, Cardiac Surgeon Larry Stephenson has been exploring other applications. By wrapping conditioned skeletal muscle into a fist-size pouch, he has created a mini-pumping chamber that he hopes can be used to boost circulation. Implanted in animals, the pouches, which may be located almost anywhere in the body, have enhanced blood flow as much as 20% for eight hours. Stephenson believes that such auxiliary pumps could reduce the need for risky open-heart surgery. They might also obviate the need for transplants for patients whose hearts are weak but not completely failing. Implanting such a pumping chamber would be simpler and cheaper than performing a heart transplant, and since the borrowed muscle is the individual's own, it would not be rejected. Patients might even benefit psychologically, notes Stephenson, from knowing that their body has helped heal itself.

With reporting by Christine Gorman/New York