RESUMEN
BACKGROUND: The radial approach has been increasingly used worldwide for diagnostic and therapeutic cardiac catheterization. The radial artery caliber is one of the limitations of its use. The objective of this study was to describe the anatomy of the radial and ulnar arteries, as well as to develop a radial artery diameter prediction score using clinical and anthropometric criteria. METHODS: Using vascular ultrasound with bilateral radial and ulnar artery measurements, 1,180 patients who underwent cardiac catheterization or angioplasty procedures were prospectively evaluated. Using the patients' variables, a radial artery diameter prediction score was developed in a cross-sectional fashion, using half of the sample. The score was validated with the half not used for deriving the model. RESULTS: A total of 1,180 patients were evaluated. The mean internal diameter of the right and left radial arteries was 2.69±0.69mm and 2.53±0.64mm (p<0.01), and the mean internal diameter of the right and left ulnar arteries was 2.09±0.59mm and 2.10±0.60mm (p=0.76), respectively. The factors that positively correlated with arterial size were male sex, previous catheterization, height, weight, and body surface area. The risk score developed using clinical and anthropometric variables had unsatisfactory discriminatory capacity (c-statistics 0.64). CONCLUSION: The right radial artery is the largest forearm artery in most cases. Men and patients who had previously undergone catheterization have a larger mean radial artery diameter. The artery diameter prediction score has modest accuracy for clinical use. (AU)