Comparison of the morphologic and vascular reactivity of the proximal and distal radial artery

Background. Variations in the morphology and vascular reactivity of the proximal and distal radial artery might influence its performance as a bypass conduit. Methods. The morphologic and functional characteristics of the proximal and distal RAs were compared with those of the left and right internal mammary arteries by using histologic and in vitro organ bath techniques. Results. Proximal RA had a significantly greater medial cross-sectional area compared with that of the distal RA (2.48 ± 0.27 mm2 compared with 1.86 ± 0.21 mm2, p< 0.05), which were both significantly greater than the left internal mammary artery (0.54 ± 0.09 mm2) or the right internal mammary artery (0.67 ± 0.03 mm2). Proximal RA had a significantly greater response to 90 mmol/L potassium chloride than that of distal RA (88.4 ± 7.3 compared with 60.2 ± 10.3 mN, p< 0.05), and both contracted more than the left internal mammary artery (30.3 ± 2.9 mN) and the right internal mammary artery (32.6 ± 4.1 mN). There was no difference in the response to noradrenaline and adrenaline between proximal and distal RA, both of which contracted more than the left and right internal mammary arteries. Conclusions. When choosing a segment of RA for use as a bypass conduit, regional variations in biologic properties should be considered.