Comparison of hemodynamic responses during dynamic exercise in the upright and supine postures after orthotopic cardiac transplantation.

Abnormal hemodynamic responses during supine exercise have been well documented in orthotopic cardiac transplant recipients. To determine the effect of posture, central hemodynamics were studied in 20 patients during a change from supine to sitting and during graded upright bicycle exercise (group U) and were compared with those of 20 patients matched for age, gender and time from transplantation who were studied after passive leg elevation and during exercise in the supine posture (group S). Passive leg elevation resulted in a 9% increase in stroke index (34 +/- 6 to 37 +/- 6 ml/m2, p less than 0.001) and a 10% increase in cardiac index (3.1 +/- 0.4 to 3.4 +/- 0.5 liters/min per m2, p less than 0.001) in group S patients compared with a 15% reduction in stroke index (34 +/- 7 to 29 +/- 6 ml/m2, p less than 0.001) and a 9% decrease in cardiac index (3.2 +/- 0.6 to 2.9 +/- 0.5 liters/min per m2, p less than 0.001) in group U patients on assuming the sitting posture. Likewise, both the pulmonary capillary wedge pressure and right atrial pressure increased significantly (13 +/- 4 to 17 +/- 8 mm Hg, p less than 0.001 and 5 +/- 3 to 7 +/- 3 mm Hg, p less than 0.001) with passive leg elevation in group S and decreased on sitting (12 +/- 6 to 8 +/- 5 mm Hg, p less than 0.001 and 5 +/- 3 to 3 +/- 2, p less than 0.001) in group U.(ABSTRACT TRUNCATED AT 250 WORDS)