The procedure of a heart transplant is complex: first, the patient is placed on a heart-lung machine. This is effectively an artificial heart and lungs so the surgeon can cut the blood supply to the real organs so he can operate without the patient dying. The machine pumps the blood throughout the rest of the body, removing carbon dioxide and replacing it with oxygen.
Doctors then remove the patient's heart except for the back walls of the atria. The backs of the atria on the new heart are opened and the heart is sewn into place onto the old atria walls.
Surgeons then connect the blood vessels and allow blood to flow through the heart and lungs. As the heart warms up, it begins beating. Sometimes, surgeons must start the heart with an electrical shock.
Patients are usually up and around a few days after surgery, and if there are no signs of the body immediately rejecting the organ, patients are allowed to go home within 2 weeks.
Transplants are used to treat the following conditions:
- Cardiomyopathy--a weakening of the heart muscle.
- Severe coronary artery disease--in which the heart's blood vessels become blocked and the heart muscle is damaged.
- Birth defects of the heart.
However, even with one of these conditions, the patient must fulfil the criteria of:
- Have all other therapies been tried or excluded?
- Is the patient likely to die without the transplant?
- Is the person in generally good health other than the heart disease?
- Can the patient adhere to the lifestyle changes--including complex drug treatments and frequent examinations--required after a transplant?
Heart transplants are very risky operations and, even after a succesful operation, life expectancy is not long.
The main reasons for this are because the heart is rejected by the patient’s immune system. Drugs can be used to suppress this rejection but they have severe side-effects, e.g. kidney damage, high blood pressure, osteoporosis and lymphoma (a type of cancer that affects cells of the immune system).
Coronary artery disease (atherosclerosis) is a problem that develops in almost half the patients who receive transplants. Normally, patients with this disease experience chest pain and/or other symptoms when their hearts are under stress. This is called angina and is an early warning sign of a blocked heart artery. However, transplant patients may have no early pain symptoms of a blockage building up because they have no sensations in their new hearts and so the condition can be advanced before it is discovered.
Pacemakers are used to regulate the heart’s beating when its own “bioelectrical triggering system” fails. Most patients given pacemakers suffer from a condition in which the heart beats too slowly (bradyarrhythmia). This is most commonly a result of deterioration in the heart's own pacing system in elderly patients, though high blood pressure, coronary artery disease or scarring from a heart attack can also cause the problem.
Other conditions which require pacemakers include heart block -- in which the heart stops beating altogether for several seconds and tachyarrhythmia (an overly rapid heartbeat).
The pacemaker has two parts - a battery-powered generator and the wires that connect it to the heart. The coin sized generator, which has an effective life of seven to 12 years, is implanted just beneath the skin below the collarbone. The leads are threaded into position through veins leading back to the heart. The entire implantation procedure requires only a local anaesthetic, and takes about an hour.
The most commonly installed pacing device is a demand pacemaker. It monitors the heart's activity and takes control only when the heart rate falls below a programmed minimum -- usually 60 beats per minute.
A more sophisticated type of pacemaker actually monitors a number of physical changes in the body which signal an increase or decrease in activity. If the heart's own pacing system fails to respond properly, these rate-responsive pacemakers slowly raise or lower the heartbeat to the appropriate level -- from 60 to perhaps 150 beats per minute.
