The effects of intra-arterial vasodilators on radial artery size and spasm: implications for contemporary use of trans-radial access for coronary angiography and percutaneous coronary intervention

Abstract

Transradial access (TRA) offers advantages including decreased vascular complications, reduced length of hospital stay, and reduced cost. The size of the radial artery (RA) limits the equipment that can be used via TRA. Intra-arterial (IA) vasodilators prevent and treat RA spasm, yet are not uniformly used in TRA and their effect on the absolute size of the RA remains unknown. 121 patients undergoing TRA for cardiac catheterization were included. 78 patients underwent RA angiography prior to administration of IA vasodilators ('no vasodilator' group), 43 patients underwent radial angiography after administration of an IA verapamil and nitroglycerin cocktail ('vasodilator' group). Quantitative angiography was used to compare the RA diameters. Clinical characteristics were similar between the groups, except that patients in the 'no vasodilator' cohort were taller (1.67 ± 0.1 m vs. 1.73 ± 0.1 m, p=0.002), and heavier (84.9 ± 18.2 kg vs. 75 ± 17.1 kg, p=0.003). In the 'vasodilator' group the proximal RA diameter was larger (2.29 ± 0.47 mm vs. 2.09 ± 0.41 mm, p=0.02) as was the narrowest segment (1.83 ± 0.56 mm vs 1.39 ± 0.43, p<0.0001) compared to the 'no vasodilator' group. At the RA origin, 79.4% of those in the 'vasodilator' group were larger than a 6 Fr guide catheter, compared to 51.4% in the 'no vasodilator' group (p=0.004). At the narrowest segment a higher percentage of RAs in the 'vasodilator' group were larger than a 5 Fr guide catheter (65.1% vs 26.9%, p<0.001) and a 6 Fr catheter (34.9% vs 10.3%, p=0.001). IA vasodilators increase pre-procedural RA diameter in patients undergoing cardiac catheterization via TRA. This increase in diameter has important implications for procedural planning. Boyer et al. performed a blinded controlled clinical trial investigating the effects of intra-arterial vasodilators on radial artery size and spasm during cardiac catheterization. The study demonstrates that intra-arterial vasodilators significantly increased the radial artery size throughout the entire course of the vessel and significantly decreased the amount of radial artery spasm. The authors conclude that these findings support the use of intra-arterial vasodilators during cardiac catheterization and have important implications for emerging technologies such as larger bore sheathless radial procedures.