| Objective: To compare the changes in heart rate (HR), blood pressure (BP), exercise capacity, and electrocardiogram (ECG) during and after maximum ECG cycle ergometer exercise test between the children with cardiac diseases and the healthy so as to demonstrate the use of ECG exercise test (EET) in pediatrics and its value in the evaluation of cardiac reserve in children with cardiac problems.Methods: Graded upright maximum EET with cycle EM940 were performed in 90 subjects aged from 8 to 14 years old, the subjects were separated into two groups: 26 cases with cardiac disease as research group (12 males and 14 females, mean aged 11. 5±1.6ys) and additional 64 healthy children as control group (33 males and 31 females, mean aged 11.3 ± 1.8ys ). Supine and sitting standard simultaneous 12 leads body surface ECG at resting were recorded. The blood pressure from right upper limb was also measured before thetest. The initial work load was 15W, and then 15W was increased every 3min until the exercise end points was reached. During the testing , the pedaling speed of cycle was controlled at 60~70 rpm. HR, BP and ECG at rest# during and after exercise were continuously recorded respectively, exercise capacity# exercise duration and work load were also noted for each cases. These data were statistic analysis by microcomputer with SPSS 11.0 software. Statistical methods included x±s, t test, chi-square analysis, rank sun test, and multiple liner regression analysis.Results: (1) Exercise capacity mild to moderate positive correlated with exercise duration and total work load (r in research group was 0.526,0.543 while in controls was 0.363, 0.414 respectively), mean exercise capacity in research group was lower than that of in control (P<0. 001). (2) There was no apparently difference in HR at rest for the two groups (P>0.05), while the maximal HR and HR reserve in research group was dramatically lower (P<0.001). (3) BP steady increased during exercise and BPs in research group resumed within 6min while in control group resumed within 8min after exercise. BPd resumed within 2 min and 4 min relevantly. The resting BPs in research group was lowercompared with control (P<0.05), but the peak BPs and BPs reserve were similar (P>0.05). As for BPd ,both resting value and peak value were similar (P>0.05). (4) According to the criteria of ST depression, the positive rate of EET in research group (50%) was higher compared with control (6.2%) (P<0.001). (5) In the two groups, there was no difference in RPP at rest (P>0.05), but the peak RPP in research group was lower than that of in control (P<0.001) . Conclusions: (1) Exercise capacity , RPP, and HR reserve in children with cardiac disease are lower compared with normal children. (2) There is a tendency that children with cardiac disease accompanied by decreased cardiac reserve. (3) cardiac reserve is primary affected by HR reserve. (4) It is safe for children to perform EET. EET is useful in the evaluation of cardiac reserve in children with cardiac disease.
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