Haemodynamic response to dynamic exercise after heart-lung transplantation

The purpose of this study was to investigate the haemodynamic response to dynamic exercise after heart-lung transplantation (HLT). Nine stable HLT recipients (6 males) were studied 12-55 months after transplantation. While sitting on a cycle ergometer, they first underwent a maximal symptom-limited exercise test (power increment was 10 W x min(-1)) to determine the maximal tolerable workload. On the next day, they performed a second exercise test at 0, 40, 60 and 80% of their predetermined maximal workload (mean+/-sD: 108+/-20 W). Stage duration was 6 min. Respiratory, gas exchange, and haemodynamic measurements were performed at rest, during the last minute of each stage, and after recovery. Haemodynamic variables at rest were within normal limits except heart rate (HR) which was greater and stroke volume index (SVI) which was lower than normal. Peak oxygen consumption was 61+/-8% of predicted. HR showed an initial slow increase followed by a steeper rise, and a delayed return to baseline during the recovery period. SVI and cardiac index (CI) increased at the onset of exercise but did not change significantly at 40-80% of the maximal workload. Pulmonary capillary wedge pressure increased from 4+/-2 mmHg at rest to 14+/-3 mmHg at maximal exercise. It is concluded that during dynamic exercise, heart-lung transplantation recipients demonstrate a chronotropic incompetence, a reduced increase in cardiac index and stroke volume index, and an excessive rise in left ventricular filling pressures. These alterations may contribute to the persistent exercise limitation.