Nitroglycerin dilates the radial artery and prevents
spasm, which increases the success rate of sheath cannulation through the conventional transradial approach. However, the effects of
nitroglycerin on distal radial approach (DRA) procedures are not known. The aim of this study is to elucidate whether a transdermal
nitroglycerin patch improves the rate of successful DRA cannulation. A total of 92 patients scheduled for coronary angiography by means of DRA randomly received (1:1) a transdermal
nitroglycerin patch preintegrated with the covering material or only the covering material on their upper arm on the side of the
puncture. The diameter of the distal radial artery was evaluated with ultrasound at baseline and after application. DRA procedures were performed in a double-blind fashion. The primary outcome was the rate of successful palpation-guided distal radial artery cannulation with the first
puncture. The
nitroglycerin group had larger distal radial artery diameter after patch application than that of the no-treatment group (mean, 3.21 mm vs 2.71 mm, p <0.001), but not at baseline (mean, 2.64 mm vs 2.64 mm, p = 0.965).The
nitroglycerin group had a significantly higher success rate of DRA cannulation with the first
puncture than that of the no-treatment group (59% vs 24%, p = 0.001; odds ratio 4.5, 95% confidence interval 1.9 to 11.0). The
nitroglycerin group required fewer
punctures than did the no-treatment group (median, 1 vs 3, p = 0.019). There were no significant differences in the occurrence of
hypotension between the 2 groups. No patients experienced radial artery occlusion. In conclusion, transdermal
nitroglycerin patch application safely facilitates DRA cannulation. Trial Registration: Japan Registry of Clinical Trials, https://jrct.niph.go.jp/ (identifier: jRCTs051210128).