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:
- End-stage heart failure
- Coronary artery disease
- Hypertrophic cardiomyopathy
- Congenital heart disease
Transplantation may also be indicated for patients who
- Cannot be weaned from temporary cardiac-assist devices after myocardial infarction or nontransplant cardiac surgery
- Have cardiac sequelae of a lung disorder requiring lung transplantation
The only absolute contraindication for heart transplantation is
- Pulmonary hypertension that does not respond to preoperative treatments
Relative contraindications include organ insufficiency (eg, pulmonary, renal, hepatic) and local or systemic infiltrative disorders (eg, cardiac sarcoma, amyloidosis).
General contraindications to transplantation should also be considered.
All donated hearts come from brain-dead donors, who are usually required to be < 60 years and have normal cardiac and pulmonary function and no history of coronary artery disease 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.
(See also Overview of Transplantation.)
Bridge and destination ventricular assist devices (VADs)
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 in patients who are not candidates for transplantation. The devices are more and more compact, with the goal of having the battery compartment implanted under the skin as well and using induction charging. Infection, which may originate at the skin insertion site of the drive lines, is a concern. However, there are now patients who have survived 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 hours. 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 hours is under study.
Immunosuppressive regimens vary but are similar to those for kidney transplantation or liver transplantation (eg, anti-IL-2 receptor monoclonal antibodies, a calcineurin inhibitor, corticosteroids—see table Immunosuppressants Used to Treat Transplant Rejection).
Complications of Heart Transplantation
(See also Posttransplantation Complications.)
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 month, decreases over the next 5 months, and levels off by 1 year.
Risk factors for rejection include
- Younger age
- Female recipient
- Female or black donor
- Human leukocyte antigen mismatching
- Possibly cytomegalovirus infection
Because graft damage can be irreversible and catastrophic, surveillance endomyocardial biopsy is usually done once/year; degree and distribution of mononuclear cell infiltrate and presence of myocyte injury in specimens are determined. Differential diagnosis includes perioperative ischemia, cytomegalovirus 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). The grading scale for rejection reflects progressive degrees of abnormality on histologic examination of biopsy specimens.
Manifestations of Heart Transplant Rejection by Category*
Atrial arrhythmia, cardiogenic shock
Heart failure, atrial arrhythmia
Dyspnea during exertion, low stress tolerance
* Most patients with heart transplant rejection are asymptomatic.
Cardiac allograft vasculopathy
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, cytomegalovirus 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.
Prognosis for Heart Transplantation
Survival rates at 1 year after heart transplantation are 85 to 90%, and annual mortality thereafter is about 4%.
Pretransplantation predictors of 1-year mortality include
- Need for preoperative ventilation or left ventricular assist devices
- Female recipient or donor
- Diagnoses other than heart failure or coronary artery disease
Posttransplantation predictors include
- Elevated C-reactive protein and troponin levels
Most often, death within 1 year results from acute rejection or infection; after 1 year, death most often results from cardiac allograft vasculopathy or a lymphoproliferative disorder.
Functional status of heart transplant recipients alive at > 1 year 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.
Drugs Mentioned In This Article
|Drug Name||Select Trade|
|diltiazem||CARDIZEM, CARTIA XT, DILACOR XR|