Sonography of Arteriovenous Fistulas and Grafts

Abstract

Arteriovenous fistulas (AVFs) and arteriovenous grafts (AVGs) are the vascular accesses of choice for long-term hemodialysis. Strategies to establish and maintain functioning AVFs and AVGs are essential. In addition to clinical evaluation, ultrasound plays a critical role in the evaluation and maintenance of AVFs and AVGs. AVFs have a high rate of failure to mature which can be reliably diagnosed with ultrasound. Treatable etiologies of the failure to mature can often be diagnosed with ultrasound. Causes of secondary AVG failure can also be diagnosed with ultrasound and treated. AVGs have a relatively short functional life expectancy due to a high rate of AVG thrombosis. Ultrasound is a safe, noninvasive way to diagnose vascular stenosis in both AVFs and AVGs prior to thrombosis, potentially saving the access. Routine surveillance ultrasound of asymptomatic AVFs and AVGs is controversial with conflicting studies on its benefit. Routine surveillance ultrasound of AVFs and AVGs is not common practice.

Ultrasound Diagnostics of Hemodynamic Changes in Arteriovenous Fistula for Hemodialysis: Review

“…Therefore, special attention should be paid to the vein branches detection during the pre-operative assessment of the vascular topography with a view to their timely ligation [9]. It has been established that the minimum diameter of the outflow vein, suitable for punctures and adequate hemodialysis, is 4-6 mm with a depth of no more than 5-6 mm [9,10,26,27,32,33].…”

“…However, arteriovenous fistula dysfunction occurs in more than 30 % of patients, and the maximum duration of its functioning rarely exceeds 4 years. At the same time, the patient's stay on hemodialysis therapy can reach 20 years or more [2,4,6,15,22,26,27,32]. Effective long-term treatment depends largely on the successful maturation and functioning of permanent vascular access.…”

Doppler Ultrasound in Vascular Access care: the pearls and pitfalls of flow volume measurement

“…Some authors advise placing the sample volume encompassing the whole lumen, to include the high central velocities and slower peripheral velocities 17,18 . Other authors prefer to insert the sample volume encompassing only 50-70% of the vessel lumen, stating that it reduces the interferences due to the vibration of the vessel walls 19,20 . Because blood velocity changes during the cardiac cycle, it is mandatory to obtain an average velocity.…”

Role of Doppler Ultrasonography Supplemented with Direct CT Venography in Dialysis Access Assessment

“…Functioning DVA is essential for ESRD patients. AVFs and AVGs, the preferred VA for dialysis, are problematic; AVFs have a high rate of maturation failure and AVGs have a short life expectancy (1). "Vascular Access Clinical Practice Guidelines of the ESVS" have been published in 2018.…”

“…Furthermore, DUS can also demonstrate causes of fistula dysfunction, such as stenosis, in poorly functioning fistulas allowing for treatment prior to total fistula loss In patients with AVGs dysfunction, DUS can identify AVG thrombosis, the most common cause of failure. More importantly, DUS can identify vascular stenosis prior to thrombosis, allowing for potential treatment and preservation of the AVG (1). The introduction of a well-defined standardized DUS protocol based on anatomic and hemodynamic parameters facilitates the multidisciplinary management of DVA, its monitoring and the timely prevention of any complications (2).…”