Cardiac Transplantation

PROCEDURE OF THE DAY

Cardiac Transplantation

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); both are controversial "solutions" to one of the most enduring human ailments. Post-operation survival periods now average 15 years.[1]

Worldwide there are 3,500 heart transplants performed every year; about 800,000 people have a Class IV heart defect (moribund) and need a new organ.[2] This disparity has spurred considerable research into the use of non-human hearts since 1993. It is now 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. Engineers want to fix the remaining problems with the manufactured options in the next 15 years.[1]


History

The first heart transplant involving a human was carried out by a team led by Dr James D. Hardy on the of 23 of January 1964 at the University of Mississippi Medical Center, when the heart of a chimpanzee was transplanted into the chest of a dying man. The heart beat for only 90 minutes before stopping. The procedure raised a series of ethical and moral questions, and received copious amounts of publicity. However, it also helped pave the way for human-to-human heart transplants.

The first human-to-human heart transplant was performed by cardiac surgeon Christiaan Barnard at Groote Schuur Hospital in South Africa on the 3rd December, 1967 by a team led by Dr. Christiaan Barnard. The patient was Louis Washkansky of Cape Town, South Africa, who lived for 18 days after the procedure before dying of pneumonia. Barnard transplanted a healthy heart from a deceased patient, the donor, Denise Darvall, who was rendered brain dead in a car accident.

The first successful heart transplant in the United States was done at Stanford University by doctor Norman Shumway in January, 1968. Subsequently, another transplant was done at St. Luke's Episcopal Hospital in Houston, Texas by Denton Cooley in June 1968. The donor was a teenage suicide victim (who had had an aortic coarctation repaired as a young child, also by Dr. Cooley) and the recipient, Mr. Thomas, had terminal severe cardiomyopathy. He survived 8 months before dying of rejection of the transplanted heart. A series of five subsequent heart transplants were done that month by Dr. Cooley followed by a number of transplants in Houston that year before the program was canceled, leaving only Norman Shumway at Stanford University doing heart transplants and research on the rejection phenomenon.

On 27 April 1968, French surgeon Christian Cabrol performed the first European heart transplantation in the Paris Pitié-Salpêtrière Hospital. The patient was a 66 year old man, Clovis Roblain, who survived 53 hours before dying of a pulmonary embolism.[3]

In 1984, at two years old, Elizabeth Craze became the youngest surviving heart transplant patient. Another followed shortly in 1988, when Kimberly Martinez received a heart transplant at the age of three months old from Stanford University. At one year old, she developed lymphoma which required the removal of three-fourths of her lung. She fully recovered and since 1989 has had no further problems.[4][5]

The concept of heart transplantation dates back to at least 400 AD in China. The book of Liezi tells a story of Bian Que exchanging the hearts of two warriors to balance their personal characteristics.[6]

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 for their condition, including medication, should have been considered prior to recommendation. Generally, the following causes of heart failure can be treated with a heart transplant:

* Cardiomyopathy
* Congenital heart disease
* Coronary artery disease
* Heart valve disease
* Life-threatening arrhythmias.

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.
* High pulmonary vascular resistance
* Recent thromboembolism
* Age over 60 years (some variation between centres)
* Alcohol or drug abuse

Procedures

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. The patient must also undergo many emotional, psychological, and physical tests to make sure that they are in good mental health and will make good use of their new heart. The patient is also given immunosuppressant medication so that their immune system will not reject the new heart.

Operative
Schematic of a transplanted heart with native lungs and the great vessels.

Once the donor heart has passed its inspection, the patient is taken into the operating room 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.

Orthotopic procedure

The orthotopic procedure begins with the surgeons performing a median sternotomy to expose the mediastinum. The pericardium is opened, the great vessels are dissected and the patient is attached to cardiopulmonary bypass. The failing heart is removed by transecting the great vessels and a portion of the left atrium. The pulmonary veins are not transected; rather a circular portion of the left atrium containing the pulmonary veins is left in place. The donor heart is trimmed to fit onto the patients remaining left atrium and the great vessels are sutured in place. The new heart is restarted, the patient is weaned from cardiopulmonary bypass and the chest cavity is closed.

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).

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. Doctors typically like the new recipients to leave hospitals soon after surgery because of the risk of infection in a hospital (typically 1 - 2 weeks without any complications). 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.

'Living organ' transplant

Doctors made medical history in February 2006, at Bad Oeynhausen Clinic for Thorax- and Cardiovascular Surgery, Germany, when they successfully transplanted a 'beating heart' into a patient.[7] 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[8] to six hours with proper preservation, depending on its starting condition. Rather than cooling 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.

Prognosis

The prognosis for heart transplant patients following the orthotopic procedure has greatly increased over the past 20 years, and as of May 30, 2008, the survival rates were as follows.[9]

* 1 year: 87.5% (males), 85.5% (females)
* 3 years: 78.8% (males), 76.0% (females)
* 5 years: 72.3% (males), 67.4% (females)


In a November 2008 study conducted on behalf of the U.S. federal government by Dr. Eric Weiss of the Johns Hopkins University School of Medicine, it was discovered that heart transplants- all other factors being accounted for- work better in same-sex transplants (male to male, female to female). However, due to the present acute shortage in donor hearts, this may not always be feasible.

As of the end of 2007, Tony Huesman is the world's longest living heart transplant patient, having survived for 29 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.[10]. Another noted heart transplant recipient, Kelly Perkins, climbs mountains around the world to promote positive awareness of organ donation. Perkins is the first heart transplant recipient to climb to the peaks of Mt. Fuji, Mt. Kilimanjaro, the Matterhorn, Mt. Whitney, and Cajon de Arenales in Argentina in 2007, 12 years after her transplant surgery. Dwight Kroening is yet another noted recipient promoting positive awareness for organ donation. Twenty two years after his heart transplant, he is the first to finish an Ironman competition.[11] Fiona Coote was the second Australian to receive a heart transplant in 1984 (at age 14) and the youngest Australian. At 24 years since her transplant she is also a long term survivor and is involved in publicity and charity work for the red cross, and promoting organ donation in Australia.

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