Operations carried out to replace failing body organs or tissues with healthy ones
Diseases can occasionally cause major organs, such as the heart, kidneys, or liver, to fail irreversibly. Dialysis can take over the functions of the kidneys but may lead to a deterioration in health. Dialysis also has to be carried out frequently and is time-consuming. Replacing the diseased organ with a transplanted one is usually the best long-term treatment. In the case of a failing heart or liver, a transplant may be the only chance of survival if the organ has deteriorated significantly.
Many body organs and tissues can be transplanted. Kidney transplants are now common, and liver, heart, lung, and cornea transplants are performed routinely. Transplants of the intestines and pancreas are carried out less often. More than one organ may be transplanted at the same time, as in the case of heart and lung transplants. Stem cell transplants (which have largely replaced bone marrow transplants) are also performed.
Transplants are carried out not only to treat life-threatening conditions but also to improve quality of life when a condition is not potentially fatal. For example, a damaged cornea that causes loss of vision can be repaired by a corneal graft to restore sight.
Organ and tissue transplants can be carried out only if a suitable donor organ can be found at the right time and if the person receiving the transplant has no other medical problems that could hinder his or her recovery.
Transplants are usually performed only when the tissue type and blood group of the donor and recipient are similar. This is necessary because the recipient’s immune system will attack any organ it identifies as “foreign”, a process known as rejection. Most transplant organs are removed from donors who have very recently been declared dead and who are unrelated to the recipient. However, stem cells and single kidneys can be taken from living donors without damaging their health. When stem cells or kidneys are donated by a close, living, genetic relative, often a brother or sister, the transplants are far less likely to be rejected by the recipient’s body because the tissue types are likely to match more closely.
In the case of organ transplants from a donor who has recently died, most come from people in whom brain function has ceased irreversibly but whose other organs have been kept functioning by a life-support machine.
Most transplant surgery requires general anaesthesia (see Having a general anaesthetic).
In an organ transplant, the organ to be transplanted is removed from the donor and chilled in a salt-containing solution until it reaches the operating room. This prolongs the time the organ can safely be deprived of its normal blood supply by a few hours. In most cases, the diseased organ is replaced by the donor organ. However, in kidney transplants the defective organ may be left in place and the new kidney placed in the pelvis, where it is connected to the appropriate blood vessels. During a heart transplant, the major blood vessels are connected to a heart–lung machine to oxygenate the blood and remove the carbon dioxide from it while the heart transplant is being carried out (see Surgery using a heart–lung machine).
In a stem cell transplant, cancerous or otherwise abnormal blood-producing cells are replaced by healthy cells from a related or unrelated donor, or from the recipient’s own blood before the start of treatment. They are taken directly from the blood in a procedure similar to that of a blood donation. Before the transplant, the recipient is given chemotherapy and radiotherapy to eliminate abnormal stem cells. The healthy cells are then introduced directly into the bloodstream using a catheter.
After a transplant, you will probably spend several days in a critical care unit. With all transplants except the cornea, you will need to take immunosuppressant drugs indefinitely to prevent your immune system from rejecting the new organ or tissue. You should be able to leave hospital after a few weeks if the transplant has been successful. Recovery time for a corneal graft is shorter, and it is usually possible to go home after a few days.
Transplant surgery, like other forms of major surgery, involves a risk of excessive bleeding and an adverse reaction to the anaesthetic. Transplant surgery carries a higher risk of infection than other types of surgery because immunosuppressant drugs interfere with the body’s natural defences. However, the greatest risk of this type of surgery is that the transplanted organ will be rejected by the immune system and that this will cause the organ to fail.
Following a major transplant operation, the chances of long-term survival improve significantly once the first year after the operation has passed. However, survival depends on the transplanted organ not being rejected and on the recipient remaining free of a serious infection. The best outcomes are usually in people who were otherwise healthy when the original organ failed.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.