NORMALIZATION OF UPRIGHT EXERCISE HEMODYNAMICS AND IMPROVED EXERCISE CAPACITY ONE YEAR AFTER ORTHOTOPIC CARDIAC TRANSPLANTATION

The mechanisms of improved functional capacity over the first year after cardiac transplantation are not well studied. To assess the contribution of cardiac changes to this improvement, the serial evolution of upright rest and exercise hemodynamics during graded upright bicycle exercise was studied in 17 patients at 3 and 12 months after heart transplantation. Heart rate responsiveness, reflected by rapid heart rate acceleration on sitting and rapid deceleration after exercise, developed in the first year. Pulmonary capillary wedge pressure was lower at 1 year, both at rest and at peak exercise (10 +/- 3 vs 13 +/- 5 mm Hg at rest supine and 14 +/- 6 vs 18 +/- 8 mm Hg at peak exercise, p < 0.05). Similarly, right atrial pressures were also significantly lower at 1 year (4 +/- 2 vs 6 +/- 3 mm Hg at rest supine and 6 +/- 5 vs 11 +/- 5 mm Hg at peak exercise, p < 0.05). Cardiac index at peak exercise was greater at 12 months (6.4 +/-1.3 vs 5.8 +/- 0.8 liters/min/m2, p < 0.05), mediated primarily by higher exercise heart rate (135 +/- 16 vs 125 +/- 12 beats/min, p < 0.05). In the first year after heart transplantation, improved rest and exercise hemodynamics and heart rate responsiveness contribute significantly to the improved functional capacity observed in these patients.