Magnesium sulphate during transradial cardiac catheterization: a new use for an old drug?

Objective: To assess the effect of intra-arterial magnesium on the radial artery during transradial cardiac catheterization.

Background: Transradial coronary angiography has become popular in the last decade and offers several advantages over transfemoral angiography. Radial artery spasm is a major limitation of this approach, and a vasodilatory cocktail is usually given. The aim of this study was to examine the effect of magnesium sulphate on the radial artery during cardiac catheterization.

Methods: This was a prospective, double-blind, randomized trial of 86 patients undergoing radial catheterization. Patients were randomized to receive magnesium sulphate (150 mg) or verapamil (1 mg) into the radial sheath. Radial dimensions were assessed using Doppler ultrasound. The primary endpoint of the study was a change in radial artery diameter following administration. Secondary endpoints included operator-defined radial artery spasm and patient pain.

Results: Following administration of the study drug, there was an increase in radial artery diameter in both groups (p < 0.01), although the increase seen was greater in the group receiving magnesium (magnesium 0.36 +/- 0.03 mm; verapamil 0.27 +/- 0.03 mm; p < 0.05). Administration of verapamil resulted in a fall in mean arterial pressure (MAP) (change in MAP -6.6 +/- 1.4 mmHg; p < 0.01), whereas magnesium did not have a hemodynamic effect. Severe arm pain (pain score > 5) was observed in 14 (30%) patients receiving verapamil and 9 (27%) receiving magnesium (p = NS).

Conclusion: This study demonstrates that magnesium is a more effective vasodilator when compared to verapamil, with a reduced hemodynamic effect, and is equally effective at preventing radial artery spasm. As such, the use of this agent offers distinct advantages over verapamil during radial catheterization.