A typical heart transplantation begins when a suitable donor heart is identified. The heart comes from a recently deceased orbrain dead donor, also called a beating heart cadaver. The patient is contacted by a nurse coordinator and instructed to come to the hospital for evaluation and 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 suitable condition. Learning that a potential organ is unsuitable can induce distress in an already fragile patient, who usually requires emotional support before returning home.
The patient must also undergo emotional, psychological, and physical tests to verify mental health and ability to make good use of a new heart. The patient is also given immunosuppressant medication so that the patient’s immune system does notreject the new heart.
Schematic of a transplanted heart with native lungsand the great vessels.
Once the donor heart passes inspection, the patient is taken into the operating room and given a general anaesthetic. Either an orthotopic or a heterotopic procedure follows, depending on the conditions of the patient and the donor heart.
The orthotopic procedure begins with a median sternotomy, opening the chest and exposing the mediastinum. Thepericardium is opened, the great vessels are dissected and the patient is attached to cardiopulmonary bypass. The donor’s heart is injected with potassium chloride (KCl). Potassium chloride stops the heart beating before the heart is removed from the donor’s body and packed in ice. Ice can usually keep the heart usable for four to six hours depending on preservation and starting condition. The failing heart is removed by transecting the great vessels and a portion of the left atrium. The patient’s 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 patient’s 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.
The orthotopic procedure was developed by Shumway and Lower at Stanford-Lane Hospital in San Francisco in 1958.
In the heterotopic procedure, the patient’s own heart is not removed. 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 patient’s original heart a chance to recover, and if the donor’s heart fails (e.g., through rejection), it can later be removed, leaving the patient’s original heart. Heterotopic procedures are used only in cases where the donor heart is not strong enough to function by itself (because either the patient’s body is considerably larger than the donor’s, the donor’s heart is itself weak, or the patient suffers from pulmonary hypertension).
‘Living organ’ transplant
In February 2006, at the Bad Oeynhausen Clinic for Thorax and Cardiovascular Surgery, Germany, surgeons successfully transplanted a ‘beating heart’ into a patient. Rather than cooling the heart, the living organ procedure keeps it at body temperature and connects it to a special machine called an Organ Care System that allows it to continue pumping warm, oxygenated blood. This technique can maintain the heart in a suitable condition for much longer than the traditional method.
Non-beating heart transplant
The first successful non-beating heart transplant was achieved in Australia in 2014, performed by cardiothoracic surgeon Kumud Dhital. The transplant was made possible by the development of preservation technology able to preserve a heart, resuscitate it and to assess the function of the heart. The first patient to have this surgery was 57-year-old Michelle Gribilas. Papworth Hospital in England (where the first non-beating heart transplant in Europe was carried out) stated that the technique could increase the number of hearts available for transplant by at least 25%.
Transplanted heart in the thorax of recipient
The patient is taken to the ICU to recover where they are started on immunosuppressants. When they are stable, they may move to a special recovery unit for rehabilitation. The duration of in-hospital, post-transplant care depends on the patient’s general health, how well the heart is working, and the patient’s ability to look after the new heart. Doctors typically prefer that patients leave the hospital 1–2 weeks after surgery, because of the risk of infection and presuming no complications. After release, the patient returns for regular check-ups and rehabilitation. They may also require emotional support. The frequency of hospital visits decreases as the patient adjusts to the transplant. The patient remains on immunosuppressant medication to avoid the possibility of rejection. Since the vagus nerve is severed during the operation, the new heart beats at around 100 beats per minute unless nerve regrowth occurs.
The patient is regularly monitored to detect rejection. This surveillance can be performed via frequent biopsy or a gene expression blood test known as AlloMap Molecular Expression Testing. Typically, biopsy is performed immediately post-transplant and then AlloMap replaces it once the patient is stable. The transition from biopsy to AlloMap can occur as soon as 55 days after the transplant.