Yequn Chen (Department of Cardiology, First Affiliated Hospital of Shatou University Medical College, China) and others report in Circulation: Cardiovascular Interventions that subcutaneous injection of nitroglycerin at the radial puncture site in patients undergoing transradial coronary intervention is associated with a significant reduction in radial artery occlusion.
The authors comment that while the transradial approach is increasingly preferred over the transfemoral approach in patients undergoing coronary interventions because it is associated with less bleeding and shorter hospital stays, 2.8–11.7% of patients who undergo the transradial approach develop radial artery occlusion “which persists for >1 month in about 60% of these patients”. “It is desirable to prevent radial artery occlusion as the radial artery provides an important source of blood vessel for coronary artery bypass grafting and a puncture suite for future coronary revascularisation,” they add.
Chen et al decided to review the potential of nitroglycerin to reduce the risk of radial artery occlusion because it has been shown to dilate the radial artery without effecting blood pressure. It also been show to prevent radial artery spasm and “act as a nitric oxide donor” (which, in turn, has been show to inhibit vascular thrombosis in a pig model).
In the study, 188 patients were randomised to receive subcutaneous injection of nitroglycerin (94) when undergoing transradial coronary intervention or receive subcutaneous injection of placebo (94). In the group that received nitroglycerin, radial artery diameter was significantly increased compared with baseline levels (2.48±0.45 vs. 2.45±0.46mm; p=0.003); in the placebo group, radial artery diameter was significantly decreased (2.46±0.49 at baseline vs. 2.41±0.5mm after the procedure; p<0.001). The authors report: “Importantly, the incidence of radial artery occlusion (within 24 hours) was substantially lower in the nitroglycerin-treated group than in the placebo group (5.4% vs. 14.4%; p=0.04)”.
According to Chen et al, the finding that nitroglycerin injection increases radial artery diameter is “consistent with the notion that nitroglycerin acts as a nitric oxide donor; therefore, counter acting the reduction of nitric oxide release induced by radial artery puncture and mechanical friction between the sheath and the intima”. The authors note that given that a sheath coated with nitric oxide has been shown to dilate vessel diameter, decrease inflammation, and inhibit intimal hyperplasia, local injection of nitroglycerin may have a similar effect to the use of such a sheath. “The finding of our study that subcutaneous injection of nitroglycerin at the radial artery puncture site reduces early radial artery occlusion is consistent with this notion and offers a cheaper method for reducing radial artery incidence,” they comment.
Chen et al conclude: “Our study suggests that subcutaneous injection of nitroglycerin at the radial artery puncture site can be a safe, economical and effective approach to reduce the incidence of radial artery occlusion post traditional coronary catheterisation.”