Heart transplantation

From Wikipedia, the free encyclopedia

Diagram illustrating the placement of a donor heart in an orthotopic procedure. Notice how the back of the patient's left atrium and great vessels are left in place.

Heart transplantation or cardiac transplantation, is a surgical transplant procedure performed on patients with end-stage heart failure or severe coronary artery disease. The most common procedure is to take a working heart from a recently deceased organ donor (allograft) and implant it into the patient. The patient's own heart may either be removed (orthotopic procedure) or, less commonly, left in to support the donor heart (heterotopic procedure). It is also possible to take a heart from another species (xenograft), or implant a man-made artificial one, although the outcome of these two procedures has been less successful in comparison to the far more commonly performed allografts.

1 History
2 Indications
3 Contraindications
4 Procedures
5 'Living organ' transplant
6 Prognosis
7 References
8 Footnotes

[edit] History

The first heart transplant was performed by Professor Christiaan Barnard at Groote Schuur Hospital in December 1967. The patient was a Louis Washkansky of Cape Town, South Africa, who lived for 18 days after the procedure before dying of pneumonia.The donor was Denise Darvall, who had recently been critically injured in a car accident.

[edit] Indications

In order for a patient to be recommended for a heart transplant they will generally have advanced, irreversible heart failure with a severely limited life expectancy. Other possible treatments, including medication, for their condition should have been considered or attempted prior to recommendation. Generally, the following causes of heart failure can be treated with a heart transplant:

[edit] Contraindications

Some patients are less suitable for a heart transplant, especially if they suffer from other circulatory conditions unrelated to the heart. The following conditions in a patient would increase the chances of complications occurring during the operation:

Kidney, lung, or liver disease
Insulin-dependent diabetes with other organ dysfunction
Life-threatening diseases unrelated to heart failure
Vascular disease of the neck and leg arteries.

[edit] Procedures

[edit] Pre-operative

A typical heart transplantation begins with a suitable donor heart being located from a recently deceased or brain dead donor. The transplant patient is contacted by a nurse coordinator, and instructed to attend the hospital in order to be evaluated for the operation and given pre-surgical medication. At the same time, the heart is removed from the donor and inspected by a team of surgeons to see if it is in a suitable condition to be transplanted. Occasionally it will be deemed unsuitable. This can often be a very distressing experience for an already emotionally unstable patient, and they will usually require emotional support before being sent home.

[edit] Operative

Once the donor heart has passed its inspection, the patient is taken into the operating theatre and given a general anesthetic. Either an orthotopic or a heterotopic procedure is followed, depending on the condition of the patient and the donor heart.

[edit] Orthotopic procedure

The orthotopic procedure begins with the surgeons removing the patient's faulty heart. This involves making a vertical incision through the center of the ribcage in order to expose the chest cavity. The patient is attached to a heart-lung machine, in order for the surgeons to open the pericardium and remove the heart by dissecting the great vessels leading from it. The rear section of the left atrium and the pulmonary vein are the only parts of the patient's original heart left in place. The donor heart is then trimmed, in order for it to fit onto the patients remaining left atrium and vessels. It can then be sutured in place. The newly implanted heart is restarted and the patient's chest cavity is closed.

[edit] Heterotopic procedure

In the heterotopic procedure, the patient's own heart is not removed before implanting the donor heart. The new heart is positioned so that the chambers and blood vessels of both hearts can be connected to form what is effectively a 'double heart'. The procedure can give the patients original heart a chance to recover, and if the donor's heart happens to fail (eg. through rejection), it may be removed, allowing the patients original heart to start working again. Heterotopic procedures are only used in cases where the donor heart is not strong enough to function by itself (due to either the patients body being considerably larger than the donor's, the donor having a weak heart, or the patient suffering from pulmonary hypertension).

[edit] Post-operative

The patient is taken into ICU to recover. When they wake up, they will be transferred to a special recovery unit in order to be rehabilitated. How long they remain in hospital post-transplant depends on the patient's general health, how well the new heart is working, and their ability to look after their new heart. Once the patient is released, they will have to return to the hospital for regular check-ups and rehabilitation sessions. They may also require emotional support. The number of visits to the hospital will decrease over time, as the patient adjusts to their transplant. The patient will have to remain on lifetime immunosuppressant medication to avoid the possibility of rejection. Since the vagus nerve is severed during the operation, the new heart will beat at around 100 bpm until nerve regrowth occurs.

[edit] 'Living organ' transplant

Doctors made medical history in May 2006, at Papworth Hospital in Cambridgeshire, England, when they successfuly transplanted a 'beating heart' into a patient.^[1] Normally a donor's heart is injected with potassium chloride in order to stop it beating, before being removed from the donor's body and packed in ice in order to preserve it. The ice can usually keep the heart fresh for a maximum of four to six hours, depending on its condition to start with. Rather than freezing the heart, this new procedure involves keeping it at body temperature and hooking it up to a special machine called an Organ Care System that allows it to continue beating with warm, oxygenated blood flowing through it. This can maintain the heart in a suitable condition for much longer than the traditional method.

[edit] Prognosis

The prognosis for heart transplant patients following the orthotopic procedure has greatly increased over the past 20 years, and as of Aug. 11, 2006, the survival rates were as follows.^[2]

1 years: 86.1% (males), 83.9% (females)
3 years: 78.3% (males), 74.9% (females)
5 years: 71.2% (males), 66.9% (females)

As of 2006, Tony Huesman is the world's longest living heart transplant patient, having survived for 28 years with a transplanted heart. Huesman received a heart in 1978 at the age of 20 after viral pneumonia severely weakened his heart. The operation was performed at Stanford University under American heart transplant pioneer Dr. Norman Shumway, who continued to perform the operation in the U.S. after others abandoned it due to poor results.^[3]