Exercise following heart transplantation

During the past 2 decades, heart transplantation has evolved from an experimental procedure to an accepted life-extending therapy for patients with endstage heart failure. However, with dramatic improvements in organ preservation, surgery and immunosuppressive drug management, short term survival is no longer the pivotal issue for most heart transplant recipients (HTR). Rather, a return to functional lifestyle with good quality of life is now the desired procedural outcome. To achieve this outcome, aggressive exercise rehabilitation is essential. HTR present unique exercise challenges. Preoperatively, most of these patients had chronic debilitating cardiac illness. Many HTR have had prolonged pretransplantation hospitalisation for inotropic support or a ventricular assist device. Decrements in peak oxygen consumption (VO2peak) and related cardiovascular parameters regress approximately 26% within the first 1 to 3 weeks of sustained bed rest. Consequently, extremely poor aerobic capacity and cardiac cachexia are not unusual occurrences in HTR who have required mechanical support or been confined to bed rest. Moreover, HTR must also contend with de novo exercise challenges conferred by chronic cardiac denervation and the multiple sequelae resulting from immunosuppression therapy. There is ample evidence that both endurance and resistance training are well tolerated in HTR. Moreover, there is growing clinical consensus that specific endurance and resistance training regimens in HTR can be efficacious adjunctive therapies in the prevention of immunosuppression-induced adverse effects and the reversal of pathophysiological consequences associated with cardiac denervation and antecedent heart failure. For example, some HTR who remain compliant during strenuous long term endurance training programmes achieve peak heart rate and VO2peak values late after transplantation that approach age-matched norms (up to approximately 95% of predicted). These benefits are not seen in HTR who do not participate in structured endurance exercise training. Rather, peak heart rate and VO2peak values in untrained HTR remain approximately 60 to 70% of predicted indefinitely. However, the mechanisms responsible for improved peak heart rate, VO2peak and total exercise time are not completely understood and require further investigation. Recent studies have also demonstrated that resistance exercise training may be an effective countermeasure for corticosteroid-induced osteoporosis and skeletal muscle myopathy. HTR who participate in specific resistance training programmes successfully restore bone mineral density (BMD) in both the axial and appendicular skeleton to pretransplantation levels, increase lean mass to levels greater than pretransplantation, and reduce body fat. In contrast, HTR who do not participate in resistance training lose approximately 15% BMD from the lumbar spine early in the postoperative period and experience further gradual reductions in BMD and muscle mass late after transplantation.