G2171 HCPCS - PERCUTANEOUS ARTERIOVENOUS FISTULA CREATION (AVF), DIRECT, ANY SITE, USING MAGNETIC-GUIDED ARTERIAL AND VENOUS CATHETERS AND RADIOFREQUENCY ENERGY, INCLUDING FLOW-DIRECTING PROCEDURES (E.G., VASCULAR COIL EMBOLIZATION WITH RADIOLOGIC SUPERVISION AND INTERPRETATION, WEN PERFORMED) AND FISTULOGRAM(S), ANGIOGRAPHY, ENOGRAPHY, AND/OR ULTRASOUND, WITH RADIOLOGIC SUPERVISION AND INTERPRETATION, WHEN PERFORMED