ABC | Volume 112, Nº6, June 2019

Statement Vascular Ultrasound Statement from the Department of Cardiovascular Imaging of the Brazilian Society of Cardiology – 2019 Arq Bras Cardiol. 2019; 112(6):809-849 radial artery in A; a loop PTFE graft between the basilic vein and radial artery in B; a curved PTFE graft between the artery and brachial vein in C; and a loop PTFE graft between the great saphenous vein and femoral artery in the lower limb in D. 73 The most common AVFH types are the radiocephalic and brachiocephalic; 73 however, as an alternative, they can be created between other vessels, such as the ulnar artery and basilic vein, or the brachial artery and basilic vein, but they must be superficialized. 5.2. Examination Indications The main indications for VUS in cases of AVFH are: • Preoperative vascular mapping, with planning for the procedure, including evaluation of central vessels. 74,75 • Maturation assessment, especially in obese patients. Maturation occurs when AVFH can withstand repeated venous punctures with large-caliber needles. This process can fail in up to 60% of cases. 74,76,77 • Functional follow-up of AVFH to detect complications early. • Recommendation: perform an examination before the procedure for planning and two after to reduce its failure rate. 74,78 • Contraindications for the procedure: Paget-Schroetter syndrome and deep venous thrombosis (DVT). 5.3. Technique 79 • High-tech equipment – with high-frequency and/or variable frequency linear probe. • Patient at rest in a room at ambient temperature, with the upper limb extended parallel to the body. Figure 12 – Types of brachiocephalic fistulas (Brescia-Cimino). (A) Latero-lateral between artery and vein. (B) Terminal artery – lateral vein. (C) Terminal vein – lateral artery. (D) Termino-terminal between artery and vein. • Measure the anteroposterior diameters of vessels in transverse planes. • Possible sites to measure flow volume: afferent – in the artery, 1 to 2 cm before the anastomosis; and efferent – in the vein, 1 to 2 cm after the anastomosis. • Observe the abnormalities in two-dimensional planes and analyze turbulent flows with color flow imaging • The Doppler angulation should be parallel to the blood flow (closer to 60°). 79 • Spectral Doppler characteristics: artery – low-resistance flow; vein – arterialized flow pattern. 5.4. Diagnostic Criteria 5.4.1. Protocol to Create Arteriovenous Fistulas for Hemodialysis • Choose the non-dominant member, if possible. • Follow the order: 1 st option – wrist; 2 nd option – elbow; 3 rd option – prosthesis. • Measure the arterial and venous diameter (a tourniquet can be used in themember to evaluate venous distensibility). 80,81 - Ideal venous or arterial diameter: elbow – 4 mm; wrist – 3 mm. - Minimum functional diameter: elbow – 2 mm; wrist – 1.8 mm. 72 • Measure the depth between vessels and skin surface; the ideal for puncture is < 5 mm. 79 • Measure the distance between artery and vein to be used (Figure 14). 831