The distal radial approach (DRA) is a novel catheter cannulation technique to access the distal radial artery for coronary angiography (CAG). It is associated with less occurrence of puncture site occlusion than the conventional transradial approach. However, cannulation failure occasionally occurs due to difficulty in puncturing the smaller distal radial artery. Nitroglycerin is expected to improve the rate of successful DRA via its vasodilative and vasospasm-preventive effects.
The DRA in CAG using transdermal NitroGlycerin patch (DRANG) study is a single-center, double-arm, parallel-assignment, double-blinded, randomized, controlled trial. Eligible patients with angina pectoris who are scheduled to receive CAG via DRA at the National Cerebral and Cardiovascular Center will be enrolled and allocated to the nitroglycerin group (n = 46) or the no-treatment group (n = 46). The nitroglycerin group will receive a transdermal nitroglycerin patch pre-integrated with a covering material that completely conceals the patch on their upper arm on the puncture side. The no-treatment group will receive only the covering material. Applications are performed 2-8 h before puncture while the patient wears an eye mask. Physicians who are blinded to the allocation and have similar experience with DRA puncture will perform DRA using the Seldinger technique with a 22-gauge needle. The primary outcome is the rate of successful palpation-guided distal radial artery cannulation with the first puncture. The secondary outcomes are the rate of successful distal radial artery cannulation, number of punctures, procedure time, use of ultrasound guidance, diameter of the distal radial artery and changes before and after patch application, and occurrence of arterial vasospasm, occlusion, or hypotension.
This study will allow us to determine the impact of a transdermal nitroglycerin patch on the rate of successful DRA and validate its effectiveness as a DRA pretreatment.

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