The effect of subcutaneous glyceryl trinitrate on radial artery diameter and the utility in radial access coronary angiography

INTERVENTION: The intervention will be a subcutaneous injection of glyceryl trinitrate (GTN) prior to radial artery puncture as part of a coronary angiogram. One millilitre (1ml) GTN (500 micrograms / millilitre) with 1ml lidocaine 2% will be used once only. This injection will be provided by the blinded operator performing the procedure. CONDITION: Cardiovascular ‐ Coronary heart disease Coronary artery disease;Coronary angiography;Transradial artery access; ; Coronary artery disease ; Coronary angiography ; Transradial artery access PRIMARY OUTCOME: Radial artery diameter measured using ultrasound at opposite site to that of subcutaneous injection[Measurement of radial artery pre‐injection and 1 minute post injection measured using a stopwatch] Radial artery diameter measured using ultrasound at site of subcutaneous injection[Measurement of radial artery pre‐injection and 1 minute post injection measured using a stopwatch] Time from first puncture to successful arterial sheath insertion measured using a stopwatch[At the time of successful arterial sheath insertion ] SECONDARY OUTCOME: Incidence of adverse affects associated with the use of subcutaneous glyceryl trinitrate (GTN) as reported in the patient medical record[At the time of completion of coronary angiogram] Participant satisfaction as assessed by a pain score with a Visual Analogue Scale (VAS)[Assessed post completion of coronary angiogram] Rate of conversion to transfemoral access for completion of coronary angiogram as reported by the operator and documented in the procedure report [At the time of successful completion of coronary angiogram] Total number of forward passes of the needle during radial artery puncture as assessed by operator self‐report[At the time of successful arterial sheath insertion] INCLUSION CRITERIA: Patient attending for a planned coronary angiogram – outpatient or inpatient Planned for transradial approach