Heart transplantation

A heart transplant, or a cardiac transplant, is a

Approximately 3,500 heart transplants are performed each year worldwide, more than half of which are in the US.[2] Post-operative survival periods average 15 years.^[3] Heart transplantation is not considered to be a cure for heart disease; rather it is a life-saving treatment intended to improve the quality and duration of life for a recipient.^[4]

History

American medical researcher Simon Flexner was one of the first people to mention the possibility of heart transplantation. In 1907, he wrote the paper "Tendencies in Pathology," in which he said that it would be possible one day by surgery to replace diseased human organs – including arteries, stomach, kidneys and heart.^[5]

Not having a human donor heart available, James D. Hardy of the University of Mississippi Medical Center transplanted the heart of a chimpanzee into the chest of dying Boyd Rush in the early morning of Jan. 24, 1964. Hardy used a defibrillator to shock the heart to restart beating. This heart did beat in Rush's chest for 60 to 90 minutes (sources differ), and then Rush died without regaining consciousness.^[6][7][8] Although Hardy was a respected surgeon who had performed the world's first human-to-human lung transplant a year earlier,^[9][10] author Donald McRae states that Hardy could feel the "icy disdain" from fellow surgeons at the Sixth International Transplantation Conference several weeks after this attempt with the chimpanzee heart.^[11] Hardy had been inspired by the limited success of Keith Reemtsma at Tulane University in transplanting chimpanzee kidneys into human patients with kidney failure.^[12] The consent form Hardy asked Rush's stepsister to sign did not include the possibility that a chimpanzee heart might be used, although Hardy stated that he did include this in verbal discussions.^[7][12][13] A xenotransplantation is the technical term for the transplant of an organ or tissue from one species to another.

Dr Dhaniram Baruah of Assam, India was the first heart surgeon to transplant a pig's heart in human body.^[14] However the recipient died subsequently. The world's first successful pig-to-human heart transplant was performed in January 2022 by surgeon Bartley P. Griffith of USA.^[15]

The world's first human-to-human heart transplant was performed by South African cardiac surgeon Christiaan Barnard utilizing the techniques developed by American surgeons Norman Shumway and Richard Lower.^[16][17] Patient Louis Washkansky received this transplant on December 3, 1967, at the Groote Schuur Hospital in Cape Town, South Africa. Washkansky, however, died 18 days later from pneumonia.^[16][18][19]

On December 6, 1967, at Maimonides Hospital in Brooklyn, New York, Adrian Kantrowitz performed the world's first pediatric heart transplant.^[16][20] The infant's new heart stopped beating after 7 hours and could not be restarted. At a following press conference, Kantrowitz emphasized that he did not consider the operation a success.^[21]

Norman Shumway performed the first adult heart transplant in the United States on January 6, 1968, at the

Worldwide, more than 100 transplants were performed by various doctors during 1968.[23] Only a third of these patients lived longer than three months.^[24]

The next big breakthrough came in 1983 when cyclosporine entered widespread usage. This drug enabled much smaller amounts of corticosteroids to be used to prevent many cases of rejection (the "corticosteroid-sparing" effect of cyclosporine).^[25]

On June 9, 1984, "JP" Lovette IV of

Recently, Australian researchers found a way to give more time for a heart to survive prior to the transplant, almost double the time.[33] Heart transplantation using donation after circulatory death (DCD) was recently adopted and can help in reducing waitlist time while increasing transplant rate.^[34] Critically ill patients that are unsuitable for heart transplantation can be rescued and optimized with mechanical circulatory support, and bridged successfully to heart transplantation afterwards with good outcomes.^[35]

On January 7, 2022,

• Irreversible
  lung, or liver disease^[40]
• Active cancer if it is likely to impact the survival of the patient
• Life-threatening diseases unrelated to the cause of
  systemic lupus erythematosus, sarcoidosis, or amyloidosis
• Vascular disease of the neck and leg arteries.
• High pulmonary vascular resistance – over 5 or 6 Wood units.

Relative contraindications:

• Insulin-dependent diabetes with severe organ dysfunction
• Recent thromboembolism such as stroke
• Severe obesity
• Age over 65 years (some variation between centers) – older patients are usually evaluated on an individual basis.
• Active
  alcohol, recreational drugs or tobacco
  smoking (which increases the chance of lung disease)

[41]

Patients who are in need of a heart transplant but do not qualify may be candidates for an

Complications

Potential complications include:^[42]

• Post-operative complications include infection and sepsis. The surgery death rate was 5–10% in 2011.^[43]
• Acute or chronic graft rejection

• Cardiac allograft vasculopathy

• Atrial arrhythmia
• Lymphoproliferative malignancy
• Increased risk of secondary infections due to
  immunosuppressive medication
• Serum sickness due to anti-thymocyte globulin
• Tricuspid valve regurgitation Repeated endomyocardial biopsy can cause
• Bleeding and thrombosis ^[44]

Rejection

Since the transplanted heart originates from another organism, the recipient's immune system typically attempts to reject it. The risk of rejection never fully goes away, and the patient will be on immunosuppressive drugs for the rest of their life. These drugs may cause unwanted side effects, such as an increased likelihood of infections or the development of certain cancers. Recipients can acquire kidney disease from a heart transplant due to the side effects of immunosuppressant medications. Many recent advances in reducing complications due to tissue rejection stem from mouse heart transplant procedures.^[45]

People who have had heart transplants are monitored in various ways to test for the development of rejection.^[46]

A 2022 pilot study^[47] examining the acceptability and feasibility of using video directly observed therapy to increase medication adherence in adolescent heart transplant patients showed promising results of 90.1% medication adherence compared to 40-60% typically. Higher medication variability levels can lead to fewer organ rejections and other poor outcomes.

Prognosis

The prognosis for heart transplant patients following the orthotopic procedure has improved over the past 20 years, and as of June 5, 2009 the survival rates were:^[48]

• 1 year: 88.0% (males), 86.2% (females)
• 3 years: 79.3% (males), 77.2% (females)
• 5 years: 73.2% (males), 69.0% (females)

In 2007, researchers from the

• Artificial heart
• Biological pacemaker
• Xenotransplantation

References