What Is Heart Transplantation?

Heart transplantation, also called cardiac transplantation, is the surgical replacement of a failing native heart with a healthy donor heart recovered from a deceased donor. It is the accepted treatment of last resort for advanced heart failure that no longer responds to medication, device therapy, or corrective surgery, and it is offered to patients whose expected survival without transplant is short but who are otherwise well enough to tolerate major surgery and lifelong immune suppression. The first human-to-human procedure was performed by Christiaan Barnard in Cape Town in 1967, but the operation only became durable after cyclosporine entered clinical use in the early 1980s and made rejection controllable.

The field sits at the intersection of cardiac surgery, transplant immunology, and biomedical engineering. Engineering contributions include the pumps that support patients while they wait, the perfusion systems that keep recovered organs viable in transit, and the imaging and molecular assays that detect rejection before the heart is damaged.

Candidate Selection and Organ Allocation

Candidates are evaluated for the severity of their heart failure, the reversibility of pulmonary hypertension, the condition of other organ systems, and their capacity to adhere to a demanding medication regimen. Because donor hearts are far scarcer than patients who need them, allocation is governed by a national policy that ranks waiting candidates by medical urgency rather than by waiting time alone. In the United States the Organ Procurement and Transplantation Network replaced a three-tier urgency system with a six-tier system in 2018 to give finer resolution to the sickest patients, and outcomes across the waiting list and after transplant are tracked in the OPTN and SRTR annual data report on heart transplantation. Donor hearts are matched to recipients on blood type, body size, and, where the recipient is sensitized, on the absence of antibodies against donor human leukocyte antigens.

Circulatory Support as a Bridge

Many candidates deteriorate faster than a donor organ becomes available, so mechanical circulatory support has become a standard part of the pathway. Temporary devices such as intra-aortic balloon pumps, percutaneous axial flow pumps, and venoarterial extracorporeal membrane oxygenation stabilize patients in cardiogenic shock. Durable implantable left ventricular assist devices, which use continuous flow rotary pumps rather than the pulsatile designs of the 1990s, can support a patient for years either as a bridge to transplant or as permanent destination therapy. Comparative reviews of heart transplantation and left ventricular assist device therapy note that survival with modern continuous flow pumps has narrowed the gap with transplantation for selected patients, which complicates the timing of listing decisions.

The Operation and Post-Transplant Care

The standard technique is orthotopic transplantation, in which the recipient heart is excised and the donor heart is implanted in its place on cardiopulmonary bypass. The bicaval anastomosis, which joins the superior and inferior vena cavae directly, has largely replaced the original biatrial technique because it preserves atrial geometry and reduces sinus node dysfunction and tricuspid regurgitation. Cold static storage limits ischemic time to roughly four to six hours, a constraint that machine perfusion systems are designed to relax by keeping the organ warm and metabolically active during transport. After surgery, patients receive induction and maintenance immunosuppression, typically a calcineurin inhibitor combined with an antiproliferative agent and corticosteroids, and are monitored for acute cellular rejection, antibody-mediated rejection, infection, and the diffuse coronary disease known as cardiac allograft vasculopathy. Rejection surveillance historically relied on endomyocardial biopsy, and now increasingly uses gene expression profiling and donor-derived cell-free DNA in blood. Registry analyses of survival trends across adult organ transplantation show that early mortality has fallen steadily while long-term graft loss remains the harder problem.

Applications

Heart transplantation and the technologies built around it have applications in several areas, including:

• Treatment of end-stage cardiomyopathy, congenital heart disease, and refractory ischemic heart failure
• Design and testing of ventricular assist devices and total artificial hearts
• Ex vivo organ perfusion and preservation systems
• Transplant immunology research, including tolerance induction and xenotransplantation
• Registry-based outcomes research and organ allocation policy modeling