Effect of Acute Isometric Handgrip Exercise on Vascular Function in Children with Congenital Heart Disease

• Published in: The FASEB journal Vol. 36 Suppl 1
• Main Authors: Khan, Rafique, Boyes, Natasha G, Luchkanych, Adam M S, Erlandson, Marta, Wright, Kristi D, Pockett, Charissa, Olver, T Dylan, Tomczak, Corey R
• Format: Journal Article
• Language: English
• Published: United States 01.05.2022
• ISSN: 1530-6860
• DOI: 10.1096/fasebj.2022.36.S1.L7847

The reactivity of conduit vessels such as the brachial artery is important in influencing arterial diameter, and subsequently, blood flow. Flow-mediated dilation (FMD) measures vessel reactivity. The increase in shear stimuli from transient arterial occlusion enhances arterial diameter in an endothelial-dependent manner, and this is thought to be impaired in individuals with congenital heart disease (CHD). Isometric handgrip (IHG) exercise is a proposed intervention to improve vessel reactivity by optimizing the shear stimuli to provoke changes in arterial diameter. Indeed, IHG training has been found to improve FMD in healthy adults and children. Whether IHG training improves endothelial dysfunction in CHD remains unknown. Improving vessel reactivity in the young becomes increasingly important in optimizing vascular health into adulthood. The effects of acute IHG exercise on the brachial artery were examined in children with CHD. We tested the hypothesis that acute IHG exercise would increase FMD in children with CHD. Four subjects with CHD (mean, 13 ± 1 year, 3 female) completed a single session of 4 × 2 mins of acute IHG (30% maximum voluntary contraction using the right hand) with 1-min rest intervals between bouts. Before and after IHG exercise, the right brachial artery was imaged with Duplex ultrasound using a 1-min baseline, 5 mins of forearm circulatory occlusion, followed by 3 mins of cuff deflation. Blood pressure and heart rate were measured continuously. Pre-FMD (baseline) mean arterial pressure (pre: 102 ± 17 mmHg vs. post: 110 ± 16 mmHg, p = 0.496) and heart rate (pre: 75 ± 13 bpm vs. post: 66 ± 5 bpm, p = 0.253) were not different. Baseline brachial artery diameter increased following acute IHG in 3 of 4 subjects (pre: 3.11 ± 0.45 mm vs. post: 3.23 ± 0.39 mm, Cohen's d = 0.3). Peak shear rate was greater post-IHG in 3 of 4 subjects (pre: 995 ± 346 sec vs. post: 1158 ± 501 sec , Cohen's d = 0.4). FMD% (4.7% vs. 6.3% and 8.2% vs. 10.5%) and FMD% normalized to shear rate area under the curve (AUC) ratio (2.2E-5 vs. 7.4E-5 a.u. and 3.1E-5 vs. 4.3E-5 a.u., Cohen's d = 2.0) increased post-IHG in 2 of 4 subjects. When brachial artery diameter increased, peak shear rate, FMD%, and FMD% normalized to shear rate AUC improved post-IHG in 2/3 subjects whereas subject four showed a decrease in brachial artery diameter, FMD% and FMD% normalized to shear rate AUC, with the exception of peak shear rate post-IHG. Favorable changes in brachial artery diameter, peak shear rate, FMD% and FMD% normalized to shear rate AUC following acute IHG may be a promising intervention for improving vascular tone and endothelial function in children with CHD.