RESPONSE TO UPRIGHT EXERCISE AFTER CARDIAC TRANSPLANTATION

There is little information on the hemodynamic response to upright exe rcise in patients who have undergone cardiac transplantation. We compa red the hemodynamic and metabolic response to upright bicycle exercise in 11 patients with heart transplants and 12 controls. Patients perfo rmed two tests-a steady-state test with a right heart catheter and a m aximal incremental test. During steady-state exercise at 20% of their predicted maximum workload, patients with heart transplants had a high er (mean +/- SD, p < 0.05) heart rate (108 +/- 11 vs. 96 +/- 15 beats/ min), mean systemic blood pressure (116 +/- 17 vs. 101 +/- 11 mmHg), m ean pulmonary artery pressure (29 +/- 9 vs. 22 +/- 3 mmHg), mean pulmo nary wedge pressure (14 +/- 6 vs. 9 +/- 2), pulmonary (302 +/- 101 vs. 220 +/- 50 d-Sec-cm-5 - m2) and systemic (2049 +/- 531 vs. 1459 +/- 5 20) resistance indices, and lactate concentration (3.4 +/- 1.7 vs. 1.7 +/- 0.4 mmol/l), and a lower stroke index (39 +/- 8 vs. 50 +/- 8 ml/m 2) compared with controls. Cardiac index, fight atrial pressure, and m ixed venous oxygen saturation were similar. During die maximal exercis e test, patients with heart transplants achieved a significantly lower percentage of predicted maximum heart rate (77 +/- 13 vs. 91 +/- 8%), workload (70 +/- 25 vs. 102 +/- 23%), oxygen consumption (63 +/- 11 v s. 108 +/- 19%), and ventilation (67 +/- 18 vs. 89 +/-15%) compared wi th controls. Heart transplant patients also had a lower blood pressure and anaerobic threshold. We conclude that heart transplant patients h ave an altered hemodynamic and metabolic response to upright bicycle e xercise.