(See also Overview of Transplantation.)
Heart transplantation is an option for patients who have any of the following and who remain at risk of death and have intolerable symptoms despite optimal use of drugs and medical devices:
Transplantation may also be indicated for patients who
The only absolute contraindication for heart transplantation is
Relative contraindications include organ insufficiency (eg, pulmonary, renal, hepatic) and local or systemic infiltrative disorders (eg, cardiac sarcoma, amyloidosis).
All donated hearts come from brain-dead donors, who are usually required to be < 60 and have normal cardiac and pulmonary function and no history of CAD or other heart disorders. Donor and recipient must have compatible ABO blood type and heart size. About 25% of eligible recipients die before a donor organ becomes available. Left ventricular assist devices and artificial hearts provide interim hemodynamic support for patients waiting for a transplant. However, these devices carry a risk of sepsis, device failure, and thromboembolism.
In recent years, implantable ventricular assist devices have greatly improved, and these devices are being used to treat some patients who previously would have needed heart transplantation and patients for whom transplantation is contraindicated. These devices are usually used to assist the left ventricle as interim (bridge-to-transplantation) or long-term (destination) treatment. Infection, which may originate at the skin insertion site of the drivelines, is a concern. However, there are now patients who have survived alive and have been well for several years after these devices were implanted.
Donor hearts are preserved by hypothermic storage. They must be transplanted within 4 to 6 h. The recipient is placed on a bypass pump, and the recipient heart is removed, preserving the posterior right atrial wall in situ. The donor heart is then transplanted orthotopically (in its normal position) with aortic, pulmonary artery, and pulmonary vein anastomoses; a single anastomosis joins the retained posterior atrial wall to that of the donor organ. Use of an in vitro pump system that modifies cell metabolism in the donor heart and thus may prolong transplant viability > 4 to 6 h is under study.
Immunosuppressive regimens vary but are similar to those for kidney or liver transplantation (eg, anti-IL-2 receptor monoclonal antibodies, a calcineurin inhibitor, corticosteroids—see Table: Immunosuppressants Used to Treat Transplant Rejection).
About 50 to 80% of patients have at least 1 episode of rejection (average 2 to 3); most patients are asymptomatic, but about 5% develop left ventricle dysfunction or atrial arrhythmias. Incidence of acute rejection peaks at 1 mo, decreases over the next 5 mo, and levels off by 1 yr.
Risk factors for rejection include
Because graft damage can be irreversible and catastrophic, surveillance endomyocardial biopsy is usually done once/yr; degree and distribution of mononuclear cell infiltrate and presence of myocyte injury in specimens are determined. Differential diagnosis includes perioperative ischemia, CMV infection, and idiopathic B-cell infiltration (Quilty lesions).
Mild rejection (grade 1) without detectable clinical sequelae requires no treatment; moderate or severe rejection (grades 2 to 4) or mild rejection with clinical sequelae is treated with corticosteroid pulses (500 mg or 1 g daily for several days) and antithymocyte globulin as needed (see Table: Manifestations of Heart Transplant Rejection by Category*).
Manifestations of Heart Transplant Rejection by Category*
The main complication of heart transplantation is cardiac allograft vasculopathy, a form of atherosclerosis that diffusely narrows or obliterates vessel lumina (in 25% of patients). Its cause is probably multifactorial and relates to donor age, cold and reperfusion ischemia, dyslipidemia, immunosuppressants, chronic rejection, and viral infection (adenovirus in children, CMV in adults).
For early detection, surveillance stress testing or coronary angiography with or without intravascular ultrasonography is often done at the time of endomyocardial biopsy.
Treatment is aggressive lipid lowering and diltiazem.
Survival rates at 1 yr after heart transplantation are 85 to 90%, and annual mortality thereafter is about 4%.
Pretransplantation predictors of 1-yr mortality include
Posttransplantation predictors include
Most often, death within 1 yr results from acute rejection or infection; after 1 yr, death most often results from cardiac allograft vasculopathy or a lymphoproliferative disorder.
Functional status of heart transplant recipients alive at > 1 yr is excellent; exercise capacity remains below normal but is sufficient for daily activities and may increase over time with sympathetic reinnervation. More than 95% of patients reach New York Heart Association class I cardiac status, and > 70% return to full-time employment.