Definition of Heart transplant
Heart transplant: A surgical procedure in which a diseased heart is replaced with a healthy heart from a deceased person.
The world's first heart transplant was done on December 3, 1967 by South African surgeon Christiaan Bernard (1922-2001). The recipient was Louis Washkansky, a grocer. The surgery went well. However, Mr. Washkansky was left vulnerable to infection from the large doses of immune-suppressing drugs (azathioprine and hydrocortisone) and radiation he received. He died of pneumonia 18 days after surgery.
The second human heart transplant was also done by Dr. Barnard. On Jan. 2, 1968, Dr. Barnard transplanted the heart of a young man into a retired dentist, Philip Blaiberg. (The young man was of "mixed race" while Dr. Blaiberg was white. The fact that Dr. Bernard ignored racial barriers caused a sensation in apartheid South Africa.) The amount of antirejection drugs was reduced and Dr. Blaiberg survived for 19 months and 15 days. He died of chronic organ rejection.
Heart transplant surgery has now become a standard procedure. It had been done about 100,000 times as of 2001 and was carried out on about 2,100 patients in 160 hospitals in the U.S. in 2001, with a one-year success rate of 85-90% and a five-year success rate of 75%.
There have been two main barriers to successful heart transplants. The first barrier has been rejection of the donor heart by the patient, as occurred in the case of Dr. Blaiberg. Cyclosporine, which was introduced in 1983, and other medications to control rejection have greatly improved the survival of transplant patients. The second barrier to increasing the number of successful transplantations continues to be the availability of donor hearts.
Donors are individuals who are brain dead, meaning that the brain shows no signs of life while the person's body is being kept alive by a machine. Donors may have died in an automobile accident or from a stroke, a gunshot wound, suicide, or a head injury. Most hearts come from those who die before age 45. Donor organs are located in the U.S. through the United Network for Organ Sharing (UNOS). Not enough organs are available for transplant. A patient may wait months for a transplant. More than 25% do not live long enough.
The donor heart is completely removed and quickly transported to the patient, who may be located at some considerable distance. The heart is cooled and kept in a special solution while being taken to the patient. During the operation, the patient is placed on a heart-lung machine which allows bypass of blood flow to the heart and lungs. The machine pumps the blood throughout the rest of the body, removing carbon dioxide and replacing it with oxygen needed by body tissues. The patient's heart is removed except for the back walls of the atria, the heart's upper chambers. The backs of the atria on the new heart are opened and the heart is sewn into place. Surgeons then connect the blood vessels and allow blood to flow through the heart and lungs. As the heart warms up, it begins beating. Patients are usually up and around a few days after surgery and, if there are no signs of the body immediately rejecting the heart, are home within 2 weeks.
A transplant is considered when the heart is failing and does not respond to other therapies, but the potential recipient's health is otherwise good. The leading reasons for heart transplants are: cardiomyopathy (disease of the heart muscle); severe coronary artery disease (in which the heart's blood vessels become blocked and the heart muscle is damaged); and congenital heart disease (birth defects of the heart).
A transplanted heart functions differently from the old one. Because the nerves leading to the heart are cut during the operation, the transplanted heart beats faster (about 100 to 110 beats per minute) than the normal heart (70 beats per minute). The new heart also responds more slowly to exercise and doesn't increase its rate as quickly as before.
The most common causes of death following a heart transplant are infection or rejection of the heart. Patients on drugs to prevent transplant rejection are at risk for developing kidney damage, high blood pressure, osteoporosis, and lymphoma (a malignancy of the immune system). Coronary artery disease (atherosclerosis) is a problem in almost half of patients. Normally, patients with this disease experience chest pain or other symptoms of angina when their hearts are under stress. However, transplant patients may have no early pain symptoms of a blockage building up because they have no sensations in their new hearts.
To prevent rejection, patients receive immunosuppressants. Because rejection can occur anytime after a transplant, immunosuppressive drugs are given to patients the day before the transplant and thereafter for the rest of their lives. The three main drugs now being used are cyclosporine, azathioprine, and prednisone.
To monitor for signs of heart rejection, small pieces of the transplanted heart are removed for inspection under a microscope. Called a biopsy, this procedure involves advancing a thin tube called a catheter through a vein to the heart. At the end of the catheter is a bioptome, a tiny instrument used to snip off a piece of tissue. If the biopsy shows damaged cells, the dose and kind of immunosuppressive drug may be changed. Biopsies of the heart muscle are usually performed weekly for the first 3 to 6 weeks after surgery, then every 3 months for the first year, and then yearly thereafter.
The prognosis (outlook) depends on many factors including age, general health, and response to the transplant. Nearly 85% of patients return to work or other activities they like. Many patients enjoy swimming, cycling, running, or other sports. More than 70% of heart transplant patients live at least 3 years after surgery. The 10-year survival rate after heart transplantation (as of 2001) is about 45%.Source: MedTerms™ Medical Dictionary
Last Editorial Review: 4/27/2011 5:27:15 PM
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