CASE 13814 Published on 12.07.2016

Renal arteriovenous fistula: Which US findings are expected?

Section

Uroradiology & genital male imaging

Case Type

Clinical Cases

Authors

J.A Prat-Matifoll; Q. Ordi Camprubi; C.Hernández Giraldo; A. Salazar; S. Dyer-Hartnett; C. Gonzalez Junyent

Vall Hebron Hospital,
Institut Catala de la Salut,
Radiology;
Passeig Vall Hebrón 116-119
08035 Barcelona, Spain;
Email:joanalbertpratrx@gmail.com
Patient

45 years, male

Categories
Area of Interest Abdomen, Kidney, Education, Genital / Reproductive system male ; Imaging Technique Catheter arteriography, Ultrasound, Ultrasound-Colour Doppler, Ultrasound-Spectral Doppler
Clinical History
45-year-old patient who suffered a sudden death caused by an acute myocardial infarction 2 years ago. By that time, a blood test revealed altered values of creatinine and iron-deficiency anaemia.
At that moment, creatinine values had worsened and a renal biopsy had been scheduled.
Imaging Findings
- US-guided biopsy:
A core needle biopsy was required due to a progressive worsening of renal function in our patient (Fig.1)

- Sonography and Doppler sonography:
Doppler sonography: A feeding artery, probably an interlobar artery (Fig. 2a, b) conveys blood to the arteriovenous fistula. Note the aliasing artefact caused by a high-speed flow within the feeding artery as well as in the arteriovenous fistula (Fig. 2c).

US- Spectral Doppler: The feeding artery shows a high-velocity and low-resistance waveform (Fig. 3a). This is caused by a direct arteriovenous communication avoiding the capillary bed and its high resistance, causing an increase of diastolic flow which lowers the resistive index.
The draining vein shows a pulsatile arterialized flow (Fig. 3b).

- Angiography and embolisation:
Most of these lesions are small arteriovenous fistulas, but when they are large they may cause renal ischaemia, hypertension, haematuria or haemorrhage (Fig. 4). If these complications are found, embolisation is the treatment of choice (Fig. 5, 6, 7).
Discussion
A- BACKGROUND
Renal arteriovenous fistulas are direct communications between a renal artery and vein. [1]

B- CLINICAL

Most of them are asymptomatic, but when large or symptomatic, they could cause haematuria, hypertension, haemorrhage or renal ischaemia. They occur frequently after biopsies or renal trauma. [1, 2]

C- IMAGING PERSPECTIVE

- US Findings
US Doppler may show direct arteriovenous communication with a high-flow and low resistive index in the feeding artery and a pulsatile arterialized flow in the draining vein.
Pseudoaneurysm may appear related to AV fistulas and it is seen as anechoic mass with colour flow within. [1, 2]

- Contrast-enhanced CT Findings
AV fistulas show simultaneous opacification of renal arteries and the draining vein during arterial phase.

- Angiographic Findings
Simultaneous opacification of artery and the draining vein during arterial phase (Fig. 5).
We performed a transfemoral arteriography after obtaining a vascular access by placing a 5 F sheath and subsequently angiography of the left renal artery (Simmons Sidewinder) was performed (Fig. 5a). Interlobar artery causing the AV fistula was detected and we performed a superselective catheterization of it using a microcatheter (Progreat) (Fig. 5b). The feeding artery was embolised using detachable coils (Boston Scientific Interlock; 03mmx6cm and 04mmx8cm) (Fig. 6). After using coils, flow was not interrupted and a non-adhesive liquid embolic agent (Onyx 34) was required (Fig. 7). As contrast media, we used Iopamiro (Iopamidol, Bracco). [3, 4]

D- OUTCOME

The majority of AV fistulas are asymptomatic. If symptomatic, selective percutaneous transcatheter embolization is the treatment of choice. [3]

E- TAKE HOME MESSAGE

- AV fistulas and pseudoaneurysms are the result of vascular trauma during percutaneous biopsy.

- Renal arteriovenous fistulas are direct communications between a renal artery and vein.

- The majority of these lesions are small and clinically non-relevant.

- On Doppler-US, its feeding artery may show a high-velocity, low-resistance waveform and the draining vein may show a pulsatile arterialized flow.

- When lesions are large or symptomatic, embolisation is the treatment of choice. It must be as selective as possible, to avoid extensive renal infarction.
Differential Diagnosis List
Renal arteriovenous fistula - Post biopsy
Pseudoaneurysm
A-V fistula
Final Diagnosis
Renal arteriovenous fistula - Post biopsy
Case information
URL: https://eurorad.org/case/13814
DOI: 10.1594/EURORAD/CASE.13814
ISSN: 1563-4086
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