Nitroglycerin as Spasmolytic Regimen for RAS Prevention in Radial Center

Patients will be randomized to receive either 200 microgram NTG or placebo (saline) at the beginning of the procedure soon after radial sheath placement. The operators will be blinded to both assignment. The primary outcome is the incidence of moderate to severe RAS evaluated by the operators during the radial procedure. Both NTG and placebo will be administered using an identical syringe to keep the operators blinded to the treatment allocation. Radial angiogram is mandatory to measure the diameter of both radial and ulnar arteries. Doppler ultrasound of the radial artery will be examined at the day after the procedure.