Release Date: December 17, 1993
BUFFALO, N.Y. -- An experimental surgical procedure developed by a team of University at Buffalo researchers could benefit patients who may need a heart transplant or other major invasive surgery to treat a weakened, diseased or enlarged heart.
The procedure, called free skeletal muscle patch cardiomyoplasty, has shown that skeletal-muscle fibers used to patch and strengthen a weak heart begin to function like cardiac muscle. The surgery has been performed only on animals to date.
"We have evidence that the skeletal muscle may undergo transformation in its biochemical enzymatic expression," said Michael F. Wilson, M.D., UB professor of medicine and chief cardiologist on the research team. "The skeletal-muscle fibers of the patches converted over eight weeks from their original non-fatigue-resistant enzyme pattern to fatigue-resistant, a characteristic of cardiac muscle."
The technique involves patching a damaged animal heart with 2 x 3 cm. pieces of the animal’s own abdominal muscle. A portion of the omentum, a vascular fatty apron that covers the intestine, is pulled through an incision in the diaphragm and secured over the patched heart to provide an ample blood supply to the patches.
The phenomenon of conversion of skeletal muscle to cardiac muscle function has been shown by others, Wilson said, but not in free muscle patches -- pieces of muscle that have been cut off from their blood and nerve supply. The researchers hypothesize that in this procedure the stretching and relaxing action of the underlying heart muscle was enough to stimulate the transformation.
"We also found cardiac creatine kinase (CK-2) and lactate dehydrogenase (LDH-5) type isoenzymes in the transplant," said Donald Armstrong, Ph.D., a biochemist and chair of the UB Department of Medical Technology who performed post-eight-week biochemical analyses of the skeletal-muscle patches. "This suggests that biochemical conversion has taken place."
Wilson stated that the team doesn’t know if the patches actually help the heart perform better.
"We have not demonstrated that yet," he said. "We think the potential is great, but it is unproven."
If the procedure does improve heart function in animals and is shown to be equally effective in humans, it could be a major benefit to the estimated 400,000 people diagnosed with cardiomyopathy every year, said Syde A. Taheri, M.D., UB clinical professor and the surgeon who developed and perfected the procedure.
"There is much to be done yet," he said, "but the approach has been worked out."
Cardiomyopathy, defined as an abnormality of the heart muscle that reduces its ability to pump blood, currently is treated in one of three ways, Taheri said: with medication, which he said is not very effective in lowering the mortality rate; a heart transplant, or a new surgical procedure called latissimus dorsi cardiomyoplasty.
This latter procedure involves pulling the large latissimus dorsi muscle that lines the back of the chest wall around to the front of the chest and sewing it in place around the heart, Taheri explained. A pacemaker causes the grafted skeletal muscle to contract in rhythm with the heart muscle.
Free skeletal muscle patch cardiomyoplasty, which can be performed using a laparoscope and thoracoscope without opening the chest, would be a much simpler, less invasive and less expensive operation than existing procedures, Taheri said. It also would reduce stress on the patient and shorten hospital stays.
Researchers who have presented the results of their work at professional meetings in the United States and abroad -- most recently at the International Society for Cardiovascular Surgery in Lisbon, Portugal, in August -- said the research has been received enthusiastically. Abstracts have appeared in Journal of the American College of Cardiology and Chest.
The team’s next step will be to perform paired experiments with animals to determine if the patches actually improve heart function.
Members of the team, in addition to Wilson, Armstrong and Taheri, are Robert Gatewood, M.D.; Edwin Jenis, M.D.; Allan Goldfarb, M.D.; Jacqueline Kane, RN, and Anil Grover, M.D.