CARDIOPULMONARY EXERCISE CAPACITY BEFORE AND AFTER CARDIAC TRANSPLANTATION

The aim of heart transplantation is to improve survival and exercise capacity of patients with endstage heart failure. Fifteen patients (1 female, 14 male) with a mean age of 48 years (ranging from 25-62) underwent cardiopulmonary exercise testing (CPX) before heart transplantation. 10/15 patients showed an oxygen uptake of < 4 ml/min/kg (Weber E) at the anaerobic threshold and 5/15 an oxygen uptake between 5 and 8 ml/min/kg (Weber D), so that a severe respectively very severe limitation of exercise capacity was documented before transplantation. Up to now 9/15 patients underwent heart transplantation. Cardiopulmonary exercise test could be repeated in 7 of these 9 patients, 12 up to 22 weeks following operation. Exercise capacity improved from former Weber-class E to class B in 2/5 patients, to class C in 2/5 patients, and to class D in 1/5 patient. Both patients with a preoperative class D improved to class C. Thus, in all cardiac recipients exercise capacity increased, whereas normal values were not reached. The denervation of cardiac allografts leads to a higher heart rate at rest, a delayed increase and diminished slope of exercise response and reduced heart rates at maximal effort. In 17 heart transplant recipients (3 female, 14 male) with a mean age of 53 years (ranging from 25-62), we investigated the exercise capacity with respect to the abnormal rate regulation of the donor heart, which was quantified by comparing the corresponding rate regulation of the remaining part of recipient's atrium driven by the sinus mode. P-waves of recipient's atrium were registered using a newly developed atraumatic transesophageal catheter. Over 1 year a total of 129 CPX (2-16 per patient)were performed. Results were compared with an age-matched normal control group. The mean maximal oxygen uptake was determined as 49% of Wasserman's predicted normal values. Normals reached 115%. No correlation was found between oxygen uptake at the anaerobic threshold and the lag time of rate increase of the donor hearts. There was no correlation between oxygen uptake and the difference in steepness of rate increase between donor hearts and remaining parts of recipient's right atrium and no correlation between oxygen uptake at the anaerobic threshold and the difference of rates at maximal work load. Thus, the abnormal regulation of heart rate in cardiac recipients appears not to be responsible for the reduced exercise capacity.