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A heart–lung transplant is a procedure carried out to replace both heart and lungs in a single operation. Due to a shortage of suitable donors and due to the fact that both heart and lung have to be transplanted together, it is a rare procedure; only about a hundred such transplants are performed each year in the United States.
Most candidates for heart–lung transplants have life-threatening damage to both their heart and lungs. In the US, most prospective candidates have between twelve and twenty-four months to live. At any one time, there are about 250 people registered for heart–lung transplantation at the United Network for Organ Sharing (UNOS) in the USA, of which around forty will die before a suitable donor is found.
Conditions which may necessitate a heart–lung transplant include:
- Congenital problems (defects present at birth) affecting the heart and lungs (48%);
- Pulmonary hypertension (20%);
- Cystic fibrosis (2%);
- A second transplant after the first transplant was rejected or failed to operate satisfactorily (4%).
Candidates for a heart–lung transplant are usually required to be:
- Under 55 years old;
- Have no other medical conditions (e.g. AIDS, Diabetes, Hepatitis);
- Mentally sound;
- Capable of following a post-operative regimen of exercise and immunosuppressant drugs.
Norman Shumway laid the groundwork for heart lung transplantation with his experiments into heart transplantation at Stanford in the mid 1960s. Shumway conducted the first adult heart transplant in the US in 1968.
Building on his research at Stanford, Bruce Reitz performed the first successful heart–lung transplant on Mary Gohlke in 1981 at Stanford Hospital. The transplant team at Stanford is the longest continuously active team performing these transplants.
The patient is anesthetised. When the donor organs arrive, they are checked for fitness; if any organs show signs of damage, they are discarded and the operation cancelled. Some patients are concerned that their organs will be removed and the donor organs won't be suitable. Since this is a possibility, it is standard procedure that the patient is not operated on until the donor organs arrive and are judged suitable, despite the time delay this involves.
Once suitable donor organs are present, the surgeon makes an incision starting above and finishing below the sternum, cutting all the way to the bone. The skin edges are retracted to expose the sternum. Using a bone saw, the sternum is cut down the middle. Rib spreaders are inserted in the cut, and spread the ribs to give access to the heart and lungs of the patient.
The patient is connected to a heart–lung machine, which circulates and oxygenates blood. The surgeon removes the failing heart and lungs. Most surgeons endeavour to cut blood vessels as close as possible to the heart to leave room for trimming, especially if the donor heart is of a different size than the original organ.
The donor heart and lungs are positioned and sewn into place. As the donor organs warm up to body temperature, the lungs begin to inflate. The heart may fibrillate at first – this occurs because the cardiac muscle fibres are not contracting synchronously. Internal paddles can be used to apply a small electric shock to the heart to restore proper rhythm.
Once the donor organs are functioning normally, the heart–lung machine is withdrawn, and the chest is closed.
Most patients spend several days in intensive care after the operation. If there are no complications (e.g. infection, rejection), some are able to return home after just two weeks in hospital. Patients will be given anti-rejection drugs, and antibiotics to prevent infection, this weakens the immune system. A schedule of frequent follow up visits is necessary.
The success rate of heart–lung transplants has improved significantly in recent years. The British National Health Service states that the survival rate is now around 85%, one year after the transplant was performed.
In 2004, there were only 39 heart–lung transplants performed in the entire United States and only 75 worldwide. By comparison, in that same year there were 2,016 heart and 1,173 lung transplants.