The hemodynamic responses to upright exercise after orthotopic cardiac transplant.

The study was undertaken to examine the heart rate (HR) and stroke volume (SV) responses to upright exercise in patients after orthotopic cardiac transplantation (Group A). The findings were compared to data obtained from post-coronary artery bypass surgery patients (Group B) and from healthy subjects (Group C). All three groups (n = 12 in each group) were matched for age and gender. The preexercise HR and blood pressure were significantly higher in Group A (p < 0.05), whereas the SV was significantly lower (41 +/- 4mL.beat-1 vs 63 +/- 3 and 65 +/- 2 mL.beat-1 in Group B and C respectively, p < 0.05). In Group A, at submaximal work loads, the SV was consistently lower than in Groups B and C. During the early phases of exercise, the HR was consistently higher in Group A also. Systemic vascular resistance remained significantly higher in Group A throughout exercise (p < 0.05).