Percutaneous endovascular arteriovenous fistula (endo AVF) is a minimally invasive alternative to conventional surgical dialysis access. In order to maximize flow through the cephalic vein, the preferred vessel, it may be necessary to permanently occlude competing outflow branches such as the basilic vein. Ultrasound monitoring of cephalic vein flow in the vascular lab can be used to predict the efficacy of basilic vein ligation but requires two operators to perform. We developed a simple technique to temporarily obstruct basilic vein outflow using a standard dialysis clamp that can be performed by a single vascular technologist.
With the patient in the supine position, the spring-loaded dialysis clamp is positioned over the basilic vein in the upper arm using ultrasound guidance. The clamp applies mild, painless obstruction of the basilic vein without interfering with arterial inflow or cephalic vein outflow. Cephalic vein peak systolic velocity, intraluminal diameter, and flow volume are recorded.
This technique was used in six patients four-to six weeks following the initial Endo AVF procedure. Basilic vein outflow was effectively occluded in all six cases. Cephalic vein blood flow increased significantly in each case (pre-clamp cephalic flow volume 301 ± 66.8 mL/min vs post-clamp 702 ± 156.5 mL/min after, P = 1.0) There were no complications related to the use of the dialysis clamp. The average duration of the procedure was less than 20 minutes.
Endo AVF may represent a significant advance in the creation of dialysis access but may require a variety of additional procedures to achieve adequate flow. We have successfully developed a simple non-invasive technique to predict the effect of basilic vein occlusion on cephalic vein flow that can be accomplished by a sole vascular technologist. This technique can be used to avoid unnecessary embolization of the basilic vein.
Jenna Karbo, RVT, RDMS, Texas Vascular Associates, PA