Local blood flow characteristics of arteriovenous fistulas in the forearm for dialysis.

Local flow characteristics were studied in 21 patients with end-to-side cephalic vein to radial artery fistulas, constructed in the wrist for chronic hemodialysis. Intraoperative electromagnetic flow studies indicated a mean fistula flow of 242+/-72 milliliters per minute. Approximately two-thirds of the total fistula flow was derived from antegrade flow in the proximal part of the radial artery and one-third from retrograde flow in the distal part of the radial artery. Temporary occlusion of the distal part of the radial artery caused a 36% decrease in total fistula flow. Ten patients had an initial spasm of the radial artery which abated after 20 minutes. Calculations of a cross sectional area indicate that the size of the radial artery is more important than the size of the cephalic vein or the anastomosis in limiting total fistula flow. End of vein to side of artery anastomoses are preferred to end-to-end anastomoses because immediate retrograde flow in the distal part of the radial artery contributes significantly to total fistula flow.