Patricia C. E. de Groot

Magnitude and Time Course of Arterial Vascular Adaptations to Inactivity in Humans

We demonstrate that extensive arterial vascular adaptations occur within 3-8 wk of inactivity in humans. We put forth the hypothesis that the diameter decrease represents an adaptation to a lack of variation in peak shear stress. Furthermore, an enhanced flow-mediated dilation in deconditioned arteries implies that functional vascular adaptations to inactivity are not simply the inverse of adaptations to exercise.

Exercise Performance and Activity Level in Children With Transposition of the Great Arteries Treated by the Arterial Switch Operation

The exercise capacity of children after arterial switch for transposition of the great arteries (TGA) is known to be at the lower limit of normal. We aimed to ascertain whether this results from compromised hemodynamics or deconditioning. A total of 17 children with TGA (12 male and 5 female children; age 12.1 + or - 2.0 years) treated with the arterial switch operation were compared with 20 age-matched controls (13 male and 7 female children; age 12.8 + or - 2.4 years) regarding their peak exercise capacity, peak workload, and peak heart rate, as assessed by cycle ergometry. The childrens physical activity level was monitored for a 7-day period using a pedometer and diary, and a questionnaire was used to assess physical activity participation and overprotection. The results demonstrated that TGA children showed a significantly reduced peak exercise capacity (47.4 + or - 6.4 vs 41.1 + or - 6.6 ml/kg/min; p <0.05), maximal workload (3.7 + or - 0.5 vs 3.1 + or - 0.6 W/kg; p <0.01), and maximal heart rate (189 + or - 9 vs 180 + or - 14 beats/min; p <0.05) compared to the controls. No significant differences were found in the physical activity pattern or overprotection. In conclusion, given the comparable physical activity level, but reduced exercise capacity in the TGA children, these children most likely fall short in their exercise performance because of restrictive hemodynamics rather than deconditioning from reduced daily life activity.

Vascular Function in Children With Repaired Tetralogy of Fallot

We compared the endothelial function and vascular wall characteristics of 11 children with tetralogy of Fallot (TOF) (age 13 +/- 3 years) with the characteristics of 17 age-matched peers (12 +/- 2 years). Echocardiographic Doppler measurements were performed under standardized conditions to assess (1) the carotid and femoral artery diameter and intima-media thickness, (2) brachial artery endothelial function using flow-mediated dilation, and (3) central and peripheral compliance using pulsewave velocity. In addition, the physical activity level was assessed using a validated questionnaire. We found that the physical activity level of the children with TOF was lower than that of the controls, but the difference did not reach statistical significance (4.5 vs 5.9 h/wk, p = 0.087). A significantly larger femoral artery intima-media thickness was observed in those with TOF, and the carotid and brachial artery diameter and intima-media thickness were comparable between groups. The children with TOF demonstrated a significantly lower brachial artery flow-mediated dilation than that of the controls. The central and peripheral compliance did not differ between the 2 groups. In conclusion, children with TOF demonstrated an impaired brachial artery endothelial function and increased intima-media thickness of the femoral artery compared to their healthy peers. In conclusion, our findings have, therefore, indicated that children with TOF, already at a young age, have changes in vascular function and structure.