Heart transplantation

Heart transplantation (cardiac transplantation) is the surgical replacement of a failing heart with a healthy donor heart.[1] It is the established treatment for selected patients with end-stage heart failure refractory to medical and device therapy.[1][2] The donor heart is implanted orthotopically, in the recipient's normal cardiac position.[1] Because the donor heart depends on continuous perfusion and tolerates only a few hours of cold ischemia, heart transplantation is logistically time-critical; many candidates are supported by mechanical circulatory support while awaiting an organ.[1][2]

Indications

Heart transplantation is considered for advanced heart failure (commonly New York Heart Association class III-IV) due to ischemic or non-ischemic cardiomyopathy, valvular or congenital heart disease, refractory arrhythmias, or, occasionally, intractable angina, when life expectancy and quality of life are severely limited despite optimal therapy.[1][2] Candidacy requires that other organ systems can tolerate transplantation and lifelong immunosuppression.

Contraindications

Relative and absolute contraindications include fixed, severe pulmonary hypertension (which can cause right-heart failure of the donor graft), active infection or malignancy, severe irreversible dysfunction of other vital organs not addressed by a multi-organ transplant, and factors precluding adherence; these are individualized.[1][2]

Bridge to transplant: mechanical circulatory support

Many candidates are "bridged" to transplantation with a ventricular assist device (VAD), most often a continuous-flow left ventricular assist device (LVAD), or with temporary support; some receive a VAD as destination therapy when they are not transplant candidates.[1] Mechanical support stabilizes patients and can improve end-organ function before transplantation.

Allocation: the status system

In the United States, donor hearts are allocated by medical urgency through a multi-tier status system. A six-status system took effect on October 18, 2018, replacing the prior three-tier system; it ranks candidates from the most urgent (for example, those on high-intensity temporary mechanical support such as ECMO or a non-dischargeable balloon pump) to the least urgent, with the goal of better stratifying the sickest patients and reducing waitlist mortality.[3] Allocation also accounts for blood-type compatibility, body-size matching, and distance from the donor hospital. Allocation mechanics are detailed in dedicated allocation-policy articles.

Procedure

The recipient is placed on cardiopulmonary bypass, the diseased heart is removed, and the donor heart is implanted with anastomoses of the left atrium (or both atria/bicaval technique), the aorta, and the pulmonary artery.[1] The bicaval technique, which preserves atrial geometry, is now common. After reperfusion and weaning from bypass, the new heart resumes function; temporary pacing and inotropic support are frequently needed early.[1]

Rejection and surveillance

The transplanted heart is monitored for rejection, acute cellular and antibody-mediated rejection, historically by scheduled endomyocardial biopsy, supplemented or partly replaced in many programs by noninvasive tools such as gene-expression profiling and donor-derived cell-free DNA.[1][4] A distinctive long-term complication is cardiac allograft vasculopathy (CAV), an accelerated, diffuse coronary disease that is a leading cause of late graft loss.[1] Other complications include the adverse effects of immunosuppression, infection, malignancy, and renal dysfunction. See Transplant immunology.

Outcomes

Heart transplantation substantially improves survival and quality of life for appropriately selected patients with end-stage heart failure, with most recipients surviving several years and many living a decade or more; long-term outcomes are limited chiefly by cardiac allograft vasculopathy and the consequences of chronic immunosuppression.[1] National and program-specific survival data are published by SRTR and OPTN.

History

Christiaan Barnard performed the first human-to-human heart transplant in Cape Town in 1967.[5] Early survival was poor due to rejection and infection; the field was transformed in the 1980s by the introduction of ciclosporin and by improved rejection surveillance with endomyocardial biopsy, making heart transplantation a durable therapy.[1][5]

See also

• Organ transplantation · Deceased donation
• Transplant immunology

References

• Heart Transplantation. StatPearls. NBK557571. https://www.ncbi.nlm.nih.gov/books/NBK557571/
• MedlinePlus. Heart transplant. https://medlineplus.gov/ency/article/003003.htm
• HRSA/OPTN. Heart allocation status system (six-status system, effective October 18, 2018). https://www.hrsa.gov/optn/patients/resources/heart/heart-allocation-faqs
• Transplant Rejection (surveillance). StatPearls. NBK553074. https://www.ncbi.nlm.nih.gov/books/NBK553074/
• Encyclopaedia Britannica. Christiaan Barnard. https://www.britannica.com/biography/Christiaan-Barnard (historical reference; swap to a primary/peer-reviewed history before publication where exactness matters).