Intra-Arterial Labetalol and Nitroglycerin in Preventing Radial Artery Spasm Following Transradial Angiography: A New Approach

Radial artery spasm (RAS) resulted from decreasing blood flow and activation of vasomotor system leads to a decrease in artery diameter, perfusion and patency, and increase the risk of procedure failure. In this study, we investigated the effects of intra-arterial administration of nitroglycerin and labetalol on radial artery diameter, RAS, and pain intensity in patients undergoing diagnostic radial angiography.

Sixty-four patients randomly enrolled into one of the nitroglycerin (150 μg) or labetalol (500 μg) groups. The radial artery size, and the incidence of RAS were measured before, immediately after puncture, and at the end of treatment. Pain intensity was evaluated using a visual-analog-scale (VAS) at the end of the procedure. Hemodynamic status before, and during the procedure was also recorded.

Labetalol causes a significantly larger increase in radial diameter than nitroglycerin immediately after intra-arterial injection (2.24±0.58 mm vs. 1.65±0.39 mm, P-value<0.001). The rate of RAS immediately after vasodilator administration in the labetalol group was 3.1% vs. 12.5% in the nitroglycerin group (P-value=0.355), but the overall incidence (immediately after administration+ at the end of procedure) did not show a statistically significant difference (53.125% vs 31.25% respectively, P-value=0.076). The VAS score did not show a significant difference between two groups (1.15±0.44 in nitroglycerin vs. 1.50±0.91, P-value=0.063).

Labetalol increases radial artery diameter more than nitroglycerin. However, the efficacy of labetalol in terms of RAS incidence, and patients’ pain was similar to nitroglycerin. Therefore, intra-arterial labetalol could be considered as one of the therapeutic options in clinical practice in order to reduce RAS and procedure failure.