Evidence of intact resting but exercise-induced vascular impairment in congenital heart disease.

Introduction: Young patients with CHD often display impaired peripheral vascular function, yet evidence of the effects of exercise is limited. Hypotheses: This study tested the hypothesis that 1) brachial artery reactivity and forearm microvascular function would be impaired in young patients with CHD and 2), that acute isometric handgrip (IHG) exercise would improve brachial artery reactivity and forearm microvascular function in young patients with CHD. Methods: Brachial artery flow-mediated dilation (FMD) and the reactive hyperemic response (mean brachial artery blood flow area under the curve, AUC) were tested in young patients with CHD (n = 19; 13 (4) yrs; 12 male, 7 female) and healthy age matched controls (n = 21; 13 (4) yrs, 12 male, 9 female) pre- and post-acute IHG exercise. Results: Pre-IHG exercise brachial artery FMD (4.0 (3.1) vs. 5.8 (3.9)% , P = 0.348) and reactive hyperemia (139 (69) vs. 167 (82) AUC, P = 0.449) were not different between controls and young patients with CHD, respectively. In controls, acute IHG exercise increased FMD (4.0 (3.1) to 5.9 (2.5)%, P = 0.016) and reactive hyperemia (139 (69) to 175 (75) AUC, P = 0.017). However, in young patients with CHD, acute IHG exercise only increased reactive hyperemia (167 (82) to 187 (65) AUC, P = 0.017), but not FMD (5.8 (3.9) vs. 4.9 (2.9)%, P = 0.426). Conclusions: Endothelial-dependent vasodilation is intact in young patients with CHD, but acute exercise may alter local regulatory mechanisms such that endothelial-dependent vasodilation fails to augment. Microvascular function is unaltered with CHD.