Abstract
The aim of this study was to examine the difference of time course of changes in exercise tolerance before and after open-heart cardiac surgery between elderly(E) and younger patients(C). Thirty five patients (male/female=24/11) with valvular heart disease who underwent cardiac surgery were divided into 2 groups according to age (group E;≧65 years, n=15, group C;<65 years, n=20). Serial changes in peak oxygen uptake (peak VO2), an aerobic threshold (AT VO2), respiratory function (vital capacity; VC, forced expired volume in 1 second; FEV1.0), and muscle strength of leg were evaluated in all patients, while the original cardiac rehabilitation program including aerobic exercise was performed in all patients. In group E, all parameters were significantly lower than group C before surgery (peak VO2; 16.7 ± 3.7 vs. 20.5 ± 5.5 ml/min/kg, AT VO2; 11.0 ± 2.3 vs. 12.6 ± 5.5 ml/min/kg. VC; 2.9 ± 1.0 vs. 4.1 ± 0.8 L, FEV1.0; 2.0 ± 0.6 vs. 3.3 ± 0.7 L. muscle strength; 199.5 ± 58.8 vs. 272.2 ± 78.3 N, p<0.05, respectively). Peak VO2 and AT VO2 were decreased in the early phase of after surgery (7 days after) in both groups, but only in group C, these parameters recovered to the baseline in the chronic phase of after surgery (21 days after). VC and FEV1.0 were also transiently decreased after surgery and recovered in both groups. Strength of leg muscle was decreased transiently in group C, but recovered at discharge, and that of group E did not recover at discharge. These data suggest that decrease in lower limb muscle strength after surgery may be an important factor to limit the physical activity in group E. Accordingly, it may be reasonable to perform exercise training (including muscle training) particularly in elderly patients after cardiac surgery.
