Causes of exercise limitation after heart-lung transplantation.

A decade after the first successful human heart-lung transplantation and with improved recipient survival, there is now a growing interest in the quality of life achieved after this procedure. Patients undergoing heart-lung transplantation suffer from diseases that are most protracted and uniformly fatal. Before surgery, they are usually debilitated from the primary disease and long-term inactivity. Therefore several factors contribute to the maximal work capacity achievable after transplantation. They are principally unavoidable complications of allograft transplantation, mainly lung rejection, but include the toxic effects of immunosuppressant therapy. Many, however, are a function of the prolonged incapacitation and deconditioning imposed by the pretransplant illness. The relative roles of these factors in limiting posttransplant exercise tolerance in the various disease groups undergoing heart-lung transplantation are discussed.