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Building a New Heart From Skeletal Muscle
| Article
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12663 |
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Section : |
NATURAL SCIENCE
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| Issue
Date : |
6 / 1987 |
3,966 Words |
| Author
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Dr. Larry W. Stephenson
Dr. Larry W. Stephenson is cardiothoracic surgeon at the
Hospital of the University of Pennsylvania in Philadelphia,
and associate professor of surgery, School of Medicine,
University of Pennsylvania. |
Approximately eight-and-a-half years ago, a young surgeon in training at the Hospital of the University of Pennsylvania suggested that a patient's own muscle might be used to replace a portion of the failing heart damaged by a heart attack. His superiors thought the idea was preposterous, especially in view of what was taught in standard biology and physiology courses. Little did anyone realize then that researchers would be building an entire pumping chamber from such muscle and using it as an auxiliary heart to pump blood unceasingly for weeks in a dog named Bruno. The procedure may some day offer patients a less traumatic alternative to current therapies.
Heart failure is one of the leading causes of death in the United States and is frequently caused by heart attacks. Heart attacks usually occur when arteries supplying blood to a portion of the heart become blocked, resulting in that portion of the heart muscle dying off. (The process is referred to as a myocardial infarction or "MI" by physicians.) If the area of heart muscle involved is not too large, the person will survive and that portion of the heart muscle will eventually become nonfunctioning scar tissue.
The heart's left ventricle is its main pumping chamber and is about the size of a person's fist. If a heart attack occurs there and involves an area roughly the size of one of your mother's larger chocolate chip cookies, it will probably be fatal. Those who survive a heart attack may develop chronic congestive heart failure. In this case, the damaged heart may pump only a fraction of the amount of blood a normal heart would. Fluid backs up into the lungs, the lungs become engorged, and shortness of breath occurs. The ankles as well as the addomen may become swollen. Physical activity is limited. Patients may only be able to take a few steps before becoming short of breath. Some are confined to bed.
Unfortunately, the outlook for most of these patients is dismal. New drugs are always developed and tested, but it is unlikely any will cause scar tissue that was once heart muscle to contract again.
Each year more people benefit from heart transplants; however, heart transplantation is plagued by numerous problems. About half of the patients who receive heart transplants die from rejection-related problems within five years after the surgery. Drugs used to suppress rejection are associated with numerous undesirable side effects and complications. There continues to be a significant donor shortage, frequently resulting in long waiting periods for desperately ill
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