FUNCTION OF THE TRANSPLANTED HEART - UNIQUE PHYSIOLOGY AND THERAPEUTIC IMPLICATIONS

Orthotopic heart transplantation has become an established treatment f or selected patients with refractory heart failure. Long-term survival rates are superior to those resulting from other forms of therapy for that patient population. In addition, an improved quality of life has been reported by many patients. However, despite these encouraging re sults, the transplanted heart does not provide the recipient with norm al cardiac function. Cardiac physiology after heart transplantation is unique. Resting hemodynamics differ significantly, acutely and chroni cally, from those seen in healthy subjects. In addition, neural mechan isms undergo changes as a result of surgical denervation. Afferent con trol mechanisms and efferent responses both are altered, leading to im portant clinical abnormalities. Examples include altered cardiovascula r responses to exercise, altered cardiac electrophysiology, and altere d responses to cardiac pharmacologic agents. An improved understanding of the changes in cardiac physiology, which occur after heart transpl ant, may allow the care of these patients to be optimized.