Indications and Basic Conditions for Success
Donor organ transplantation is considered when a patient is diagnosed with end-stage, absolutely untreatable heart failure. Most commonly, this state is caused by severe forms of ischemic heart disease (IHD) or progressive dilated cardiomyopathy. The post-operative prognosis is quite encouraging: statistics show that about 60% of operated patients survive for at least five years.
However, achieving this efficacy requires strict adherence to three fundamental conditions. First, the most thorough medical and immunological matching of the donor-recipient pair is essential. Second, the patient is prescribed potent and effective immunosuppressive therapy to suppress the body's natural aggression against foreign tissues. Third, physicians critically rely on early morphological diagnosis of an incipient rejection reaction. The gold standard for this monitoring is regular endomyocardial biopsy, allowing pathologists to evaluate the cellular composition of the myocardium in a timely manner.
Acute Graft Rejection
Rejection of the transplanted organ by the recipient's immune system remains the primary and most dangerous problem in modern transplantation. Timely diagnosis of this process is carried out exclusively by examining biopsy specimens obtained via endomyocardial biopsy.
Pathomorphologically, acute rejection is characterized by a cascade of destructive tissue changes:
- Marked lymphocytic infiltration (accumulation of immune cells attacking the graft) occurs in the myocardial stroma.
- Focal necrosis of the cardiac muscle tissue develops.
- Vasculitis and thrombovasculitis form, inevitably leading to severe microcirculatory disorders.
- Progressive edema of the graft tissue develops due to vascular disturbances.
- Multiple hemorrhages appear within the heart muscle.
Prognosis in acute rejection directly depends on the time of detection. In the early stages, this process is completely reversible if physicians administer intensive immunosuppressive therapy in time. However, if the reaction has progressed too far, the changes become irreversible, inevitably leading to graft failure and patient death.
Late Complications and Therapy Sequelae
Even successful engraftment does not exempt the patient from delayed risks. Lifelong immunosuppression comes at a cost: immunosuppression results in high vulnerability to various infections, and the risk of developing malignant tumors increases significantly.
A specific threat to the transplanted heart is transplant arteriosclerosis of the coronary arteries. This pathology involves diffuse proliferation (pathological overgrowth) of the inner layer of blood vessels—the intima. The vascular lumen progressively narrows, creating a massive risk for myocardial infarction.
The insidiousness of this situation lies in the fact that the transplanted heart undergoes complete surgical denervation—it lacks nerve connections to the recipient's central nervous system. Because of this denervation, acute ischemia occurs completely painlessly (latently). The patient does not feel classic angina pectoris episodes, so silent infarction often goes unnoticed, leading either to sudden cardiac death or to the development of severe congestive heart failure.