Heart transplantation

Indications and basic conditions for success

Transplantation of a donor organ is considered in situations where the patient is diagnosed with terminal, absolutely incurable heart failure. Most often, severe forms of coronary artery disease (CAD) or progressive dilated cardiomyopathy lead to this condition. The prognosis after surgery is quite encouraging: statistics show that about 60% of operated patients successfully live for at least five years.

However, achieving this level of efficacy requires strict adherence to three fundamental conditions. First, the most thorough medical and immunological matching of the donor-recipient pair is necessary. Second, the patient is prescribed potent and effective immunosuppressive therapy designed to suppress the body's natural aggression against foreign tissues. Third, doctors urgently need early morphological diagnostics of a starting rejection reaction. The gold standard for such monitoring is regular endomyocardial biopsy, which allows pathologists to timely examine the cellular composition of the myocardium.

Acute graft rejection

It is the rejection of the transplanted organ by the recipient's immune system that remains the main and most dangerous problem in all of modern transplantology. Timely diagnostics of this process are carried out exclusively by examining biopsy specimens obtained via endomyocardial biopsy.

The pathomorphological picture of an acute rejection reaction is characterized by a whole cascade of destructive changes in the tissues:

• Pronounced lymphocytic infiltration (an accumulation of immune cells attacking the graft) occurs in the myocardial stroma.
• Focal necrosis of the heart muscle tissue develops.
• Vasculitis and thrombovasculitis form, which inevitably lead to severe microcirculatory disorders.
• Due to vascular disorders, progressive edema of the graft tissue develops.
• Multiple hemorrhages appear within the heart muscle.

The prognosis in acute rejection directly depends on the time of detection. In the early stages, this process is completely reversible if doctors manage to apply intensive immunosuppressive therapy. But if the reaction has gone too far, the changes become irreversible, which inevitably leads to the loss of the graft and the patient's death.

Late complications and therapy consequences

Even successful engraftment of the organ does not spare the patient from delayed risks. Lifelong immunosuppression comes at a price: the consequence of immunosuppression is the body's high vulnerability to various infections, as well as a significantly increased risk of developing malignant tumors.

A specific threat to the transplanted heart is transplant arteriosclerosis of the coronary arteries. The essence of this pathology lies in diffuse proliferation (pathological overgrowth) of the inner lining of blood vessels — the intima. The lumen of the arteries gradually narrows, creating a colossal risk of myocardial infarction.

The insidiousness of the situation lies in the fact that the transplanted heart undergoes complete surgical denervation — it lacks nerve connections to the recipient's central nervous system. Due to this denervation, acute ischemia proceeds completely painlessly (latently). The patient does not feel classic angina attacks, so latent infarction often goes unnoticed and leads either to sudden death or to the development of severe congestive heart failure.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Pathogenesis of dilated cardiomyopathy as an indication for transplantation
• Morphological differences between focal myocardial necrosis and coagulation necrosis
• Mechanisms of development of vasculitis and thrombovasculitis during rejection
• Spectrum of infections and tumors against the background of immunosuppressive therapy
• Pathogenesis of congestive heart failure in arteriosclerosis

Other topics in the section "Pathology of the Cardiovascular System"

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.