Endothelium-independent dilation in children and adolescents.

Peak brachial artery dilation post-nitroglycerin (NTG) administration occurs between 3 and 5 min in adults. The purpose of this study was to identify the time to peak dilation response to sublingual NTG (0·3 mg) in youth. Endothelium-independent dilation (EID) was measured in 198 healthy (113 males, 85 females) youth (6-18 years) via ultrasound imaging of the brachial artery following NTG administration. Time to peak EID was 268 s following NTG administration, with no significant (P = 0·6) difference between males and females. There was a significant (P<0·001) difference between EID post-NTG at the 3 versus 4 min, 4 versus 5-min, and 3 versus 5 min time points. Peak EID (males: 24·8 ± 0·5 versus females: 25·3 ± 0·6%, P = 0·6) was not significantly different after accounting for baseline diameter. Peak response to NTG administration occurs between 4 and 5 min. The results demonstrate the importance of measuring EID up to 5-min post-NTG administration in youth.