Basis for aerobic impairment in patients after heart transplantation.
METHODS
To evaluate the physiologic basis for the suboptimal peak oxygen uptake observed after heart transplantation, we calculated the functional aerobic impairment ([(peak predicted oxygen uptake-peak observed oxygen uptake)/peak predicted oxygen uptake] x 100) and related it to donor/recipient, operative, and maximal exercise variables. Fifty-seven heart transplant recipients (mean age 50 +/- 10 years, 1 to 9 years after transplantation) underwent maximal upright cycle exercise testing. Concomitant exercise central hemodynamic measurements were obtained in 36 patients (63%).


RESULTS
The mean peak oxygen uptake was 21.7 +/- 6.5 ml/kg/min and functional aerobic impairment was 34% +/- 17%. Functional aerobic impairment correlated positively (p < 0.01) with peak systemic vascular resistance (r = 0.55) and negatively with peak cardiac index (r = -0.62) and peak systemic arteriovenous oxygen difference (r = -0.66). A weak correlation was found between functional aerobic impairment and the duration of cardiac disease (r = 0.35, p < 0.01) but not the origin of heart failure. No correlation was seen between functional aerobic impairment and donor age, total ischemic time, time since transplantation, recipient age, and resting and exercise right and left ventricular filling pressures.


CONCLUSIONS
These results suggest that the decreased exercise capacity observed in heart transplant recipients is in part due to increased peripheral vascular resistance and decreased oxygen extraction possibly due to skeletal muscle atrophy. These factors may be the result of irreversible changes from long-standing heart disease, deconditioning, or the effect of cyclosporine and prednisone.
Bussières
L M
LM
Faculty of Kinesiology, University Hospital, University of Western Ontario, London, Canada.
Pflugfelder
P W
PW
Menkis
A H
AH
Novick
R J
RJ
McKenzie
F N
FN
Taylor
A W
AW
Kostuk
W J
WJ
D000328:Adult; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D016027:Heart Transplantation / Q000502:physiology*; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000503:physiopathology; D010100:Oxygen / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology; D011183:Postoperative Complications / Q000175:diagnosis / Q000503:physiopathology*; D014655:Vascular Resistance / Q000502:physiology
D010100:Oxygen