Heart Transplant | Guide to Heart Disease
Heart transplant is a chance for patients who have any of the following conditions and are at high risk of death and severe symptoms despite optimal use of drugs and medical devices:
· End-stage heart failure;
· Coronary artery disease;
· Hypertrophic cardiomyopathy;
· Congenital heart disease.
Transplantation can also be indicated for patients who:
· Cannot be weaned from temporary cardiac assistive devices after myocardial infarction or non-transplant cardiac surgery;
· Have heart complications of lung disease requiring lung transplantation;
The only absolute contraindication for heart transplantation is pulmonary hypertension that does not respond to the preoperative treatment.
Relative contraindications include:
· organ failure (e.g., pulmonary, renal, hepatic)
· local or systemic infiltrative disorders (e.g., heart sarcoma, amyloidosis).
General contraindications for transplantation should also be taken into account.
All organs are harvested from donors with documented brain death, who usually must be <60 years of age with normal heart and lung function and have no history of coronary artery disease or other heart diseases. The donor and recipient must have the same ABO blood group and heart size. About 25% of needy recipients die before the selection of a suitable donor organ. Left ventricular support machines and artificial heart provide temporary hemodynamics for patients awaiting transplants. However, this apparatus carries the risk of sepsis, apparatus failure, and thromboembolism.
The donated heart is stored under hypothermia. It must be transplanted within 4-6 hours. The recipient is on a heart-lung machine; the heart of the recipient is removed, preserving in situ the posterior wall of the right atrium. Then the donor’s heart is transplanted orthotopically (in a normal position) with the formation of aortic anastomoses, anastomoses of the pulmonary arteries and veins; a simple anastomosis connects the remaining posterior wall of the atrium to the donor organ. The use of an in vitro pumping system that alters the metabolism of donor heart cells and, therefore, prolongs its viability before transplantation by more than 4-6 hours is under study.
Immunosuppressive regimens are varied but similar to those used in kidney transplants and liver transplants (for example, monoclonal antibodies to IL-2 receptors, calcineurin inhibitors, corticosteroids.
50–80% of patients have at least 1 episode of rejection (average 2–3); most patients are asymptomatic, but about 5% develop pulmonary ventilation dysfunction or atrial arrhythmias. The maximum number of cases of acute rejection occurs in the 1st month. Their number decreases in the next 5 months and stabilizes by the year.
Risk factors for rejection include:
· Younger age;
· Female recipient;
· Female or black donor;
· Mismatch in the main human histocompatibility complex
· Possibly cytomegalovirus infection
Since damage to the graft can be irreversible and catastrophic, an endomyocardial biopsy is performed once a year. The degree and prevalence of mononuclear cell infiltrate, and the presence of damaged myocytes are determined in the samples. Differential diagnosis excludes ischemia around the operating area, cytomegalovirus infection, idiopathic B-cell infiltration (Quilty effect).
Mild rejection (stage 1) without significant clinical manifestations does not require any treatment. Moderate to severe rejection (stages 2 to 4) or mild with clinical manifestations are treated with pulse therapy with corticosteroids (500 mg or 1 g daily for several days) and anti-thymocyte globulin if necessary. The deviation rating scale displays progressive levels of change on histological examination of biopsy specimens.