Heart transplantation, also called cardiac transplantation, is the replacement of a patient's diseased or injured heart with a healthy donor heart.
Heart transplantation is performed on patients with end-stage heart failure or some other life-threatening heart disease. Before a doctor recommends heart transplantation for a patient, all other possible treatments for his or her disease must have been attempted. The purpose of heart transplantation is to extend and improve the life of a person who would otherwise die from heart failure. Most patients who have received a new heart were so sick before transplantation that they could not live a normal life. Replacing a patient's diseased heart with a healthy, functioning donor heart often allows the recipient to return to normal daily activities.
Patients are not limited by age, sex, race, or ethnicity. In 1999, the primary diagnoses of adult patients receiving cardiac transplantation include coronary artery disease, cardiomyopathy, congenital diseases, and re-transplantation associated with organ rejection. Characteristics of patient presentation include cardiomegaly, severe dyspnea, and peripheral edema.
Adults with end-stage heart failure account for 90% of heart transplant recipients. Pediatric patients make up the remaining 10%, with 50% of those going to patients under the age of five. In the United States, patients that receive heart transplant are 73% male, 77% are white, 19% are ages 35–49, and 51% are ages 50–64.
Because healthy donor hearts are in short supply, strict rules dictate criteria for heart transplant recipients. Patients who may be too sick to survive the surgery or the side effects of immunosuppressive therapy would not be good transplant candidates.
These conditions are contraindications for heart transplantation:
Patients with end-stage heart disease unresponsive to medical treatment may be considered for heart transplantation. Potential candidates must have a complete medical examination before they can be put on the transplant waiting list. Many types of tests are done, including blood tests, x rays, and tests of heart, lung, and other organ function. The results of these tests indicate to doctors how serious the heart disease is and whether or not a patient is healthy enough to survive the transplant surgery .
A person approved for heart transplantation is placed on the heart transplant waiting list of a heart transplant center. All patients on a waiting list are registered with the United Network for Organ Sharing (UNOS). UNOS has organ transplant specialists who run a national computer network that connects all the transplant centers and organ-donation organizations.
When a donor heart becomes available, information about the donor heart is entered into the UNOS computer and compared to information from patients on the waiting list. The computer program produces a list of patients ranked according to blood type, size of the heart, and how urgently they need a heart. Because the heart must be transplanted as quickly as possible, a list of local patients is checked first for a good match. After that, a regional list and then a national list are checked. The patient's transplant team of heart and transplant specialists makes the final decision as to whether a donor heart is suitable for the patient.
When a heart becomes available and is approved for a patient, it is packed in a sterile cold solution and rushed to the hospital where the recipient is waiting. The recipient will be contacted to return to the hospital if chronic care occurs outside of the hospital.
A description of the procedure follows:
Heart transplant recipients are given immunosuppressive drugs to prevent the body from rejecting the new heart. These drugs are usually started before or during the heart transplant surgery. Immunosuppressive drugs keep the body's immune system from recognizing and attacking the new heart as foreign tissue. Normally, immune system cells recognize and attack foreign or abnormal cells such as bacteria, cancer cells, and cells from a transplanted organ. The drugs suppress the immune cells and allow the new heart to function properly. However, they can also allow infections and other adverse effects to occur to the patient.
Because the chance of rejection is highest during the first few months after the transplantation, recipients are usually given a combination of three or four immunosuppressive drugs in high doses during this time. Afterwards, they must take maintenance doses of immunosuppressive drugs for the rest of their lives.
The total cost for heart transplantation varies, depending on where it is performed, whether transportation and lodging are needed, and whether there are any complications. The costs for the surgery and first year of care are estimated to be about $250,000. The medical tests and medications after the first year cost about $21,000 per year.
Insurance coverage for heart transplantation varies, depending on the policy. Most commercial insurance companies pay a certain percentage of heart transplant costs. Medicare pays for heart transplants if the surgery is performed at Medicare-approved centers. Medicaid pays for heart transplants in 33 states and in the District of Columbia.
Before patients are put on the transplant waiting list, their blood type is determined so a compatible donor heart can be found. The heart must come from a person with the same blood type as the patient, unless it is blood type O negative. A blood type O negative heart is a universal donor and is suitable for any patient regardless of blood type.
A panel reactive antibodies (PRA) test is also done before heart transplantation. This test tells doctors whether or not the patient is at high risk for having a hyperacute reaction against a donor heart. A hyperacute reaction is a strong immune response against the new heart that happens within minutes to hours after the new heart is transplanted. If the PRA shows that a patient has a high risk for this kind of reaction, then a crossmatch is done between a patient and a donor heart before transplant surgery. A crossmatch checks how close the match is between the patient's tissue type and the tissue type of the donor heart. Most people are not high risk, and a crossmatch usually is not done before the transplant because the surgery must be done as quickly as possible after a donor heart is found.
While waiting for heart transplantation, patients are given treatment to keep the heart as healthy as possible. They are regularly checked to make sure the heart is pumping enough blood. Intravenous medications may be used to improve cardiac output. If these drugs are not effective, an intra-aortic balloon pump or ventricular-assist device can maintain cardiac output until a donor heart becomes available.
Immediately following surgery, patients are monitored closely in the intensive care unit (ICU) of the hospital for 24–72 hours. Most patients need to receive oxygen for four to 24 hours following surgery. Continuous cardiac monitoring is used to diagnose and treat donor heart function. Renal, liver, brain, and pulmonary functions are carefully monitored during this time.
Heart transplant patients start taking immunosuppressive drugs before or during surgery to prevent immune rejection of the heart. High doses of immunosuppressive drugs are given at this time, because rejection is most likely to happen within the first few months after the surgery. A few months after surgery, lower doses of immunosuppressive drugs usually are given, and then must be taken for the rest of the patient's life.
For six to eight weeks after the transplant surgery, patients usually come back to the transplant center twice a week for physical examinations and medical tests, which check for any signs of infection, rejection of the new heart, or other complications.
In addition to physical examination , the following tests may be done during these visits:
During the physical examination, the blood pressure is checked and the heart sounds are listened to with a stethoscope to determine if the heart is beating properly and pumping enough blood. Kidney and liver functions are checked because these organs may lose function if the heart is being rejected.
An endomyocardial biopsy is the removal of a small sample of the heart muscle. This is done by cardiac catheterization . The heart muscle tissue is examined under a microscope for signs that the heart is being rejected. Endomyocardial biopsy is usually done weekly for the first four to eight weeks after transplant surgery, and then at longer intervals after that.
The most common and dangerous complications of heart transplant surgery are organ rejection and infection. Immunosuppressive drugs are given to prevent rejection of the heart. Most heart transplant patients have a rejection episode soon after transplantation. Rapid diagnosis ensures quick treatment, and when the response is quick, drug therapy is most successful. Rejection is treated with combinations of immunosuppressive drugs given in higher doses than immunosuppressive maintenance. Most of these rejection situations are successfully treated.
Infection can result from the surgery, but most infections are a side effect of the immunosuppressive drugs. Immunosuppressive drugs keep the immune system from attacking the foreign cells of the donor heart. However, the suppressed immune cells are then unable to adequately fight bacteria, viruses, and other microorganisms. Microorganisms that normally do not affect persons with healthy immune systems can cause dangerous infections in transplant patients taking immunosuppressive drugs.
Patients are given antibiotics during surgery to prevent bacterial infection. They may also be given an antiviral drug to prevent virus infections. Patients who develop infections may need to have their immunosuppressive drugs changed or the dose adjusted. Infections are treated with antibiotics or other drugs, depending on the type of infection.
Other complications that can happen immediately after surgery are:
About half of all heart transplant patients develop coronary artery disease one to five years after the transplant. The coronary arteries supply blood to the heart. Patients with this problem develop chest pains called angina. Other names for this complication are coronary allograft vascular disease and chronic rejection.
Heart transplantation is an appropriate treatment for many patients with end-stage heart failure. The outcomes of heart transplantation depend on the patient's age, health, and other factors. According to a year 2000 data from the Registry of the International Society for Heart and Lung Transplantation (ISHLT), 81% of transplant recipients survive one year. During the first year, infection and acute rejection are the leading causes of death. A constant 4% decrease occurs yearly after the first year as the incidence of coronary allograft vascular disease increases.
Pediatric patients less than one year of age are least likely to reject the donor heart, but 30% of older pediatric patients succumb to transplant rejection.
After transplant, most patients regain normal heart function, meaning the heart pumps a normal amount of blood. A transplanted heart usually beats slightly faster than normal because the heart nerves are cut during surgery. The new heart also does not increase its rate as quickly during exercise . Even so, most patients feel much better and their capacity for exercise is dramatically improved from before they received the new heart. About 90% of survivors at five years will have no symptoms of heart failure. Patients return to work and other daily activities. Many are able to participate in sports.
End-stage heart disease is associated with a high mortality rate even with associated medical treatment. With as many as 30,000 patients awaiting transplantation according to the ISHLT database, and only 2,196 transplants performed in 2000, viable alternatives are necessary. Additionally, 500,000 patients in the United States are diagnosed with cardiac failure, adding to the almost 4.5 million already affected. Data from the REMATCH trial, published in 2001, demonstrated ventricular assist to be a viable alternative for patients not eligible for cardiac transplant compared to medical therapy alone. After one year, quality of life was improved in patients who received ventricular assist device compared to medical therapy alone. Additionally, biventricular pacing and myocardial resection for ventricular restoration show promising results. Adding destination therapies such as the AbioCor total artificial heart and the Thoratec Heart-Mate VE may provide other alternatives for the transplant candidate.
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American Council on Transplantation. P.O. Box 1709, Alexandria, VA 22313. (800) ACT-GIVE.
Health Services and Resources Administration, Division of Organ Transplantation. Room 11A-22, 5600 Fishers Lane, Rockville, MD 20857.
United Network for Organ Sharing (UNOS). 1100 Boulders Parkway, Suite 500, P.O. Box 13770, Richmond, VA 23225-8770. (804) 330-8500. http://www.unos.org .
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Allison J. Spiwak, MSBME
According to the American Heart Association, there are currently 196 centers performing cardiac transplant surgery in the United States. To meet criteria to be listed with UNOS, centers must perform 12 cardiac transplants per year with a one-year survival of 70%. A cardiac surgeon with additional training in transplant surgery will be consulted to perform the operation.