FISTULA A-VFISTULA A-V

Alexandru AndritoiuESC, Artery Research (Cambridge)European Atherosclerosis Society

TIPURI DE FISTULA A-VTIPURI DE FISTULA A-V

• Congenitale

• Post-traumatice

• Leziuni vasculare prin impuscare

• Chirurgicale (dializa)

(1) fistula nativa

(2) graft

The fistula is the “gold standard” because:

• It has a lower risk of infectionlower risk of infection than grafts or catheters • It has a lower tendency to clotlower tendency to clot than grafts or catheters • It allows for greater blood flowgreater blood flow, increasing the

effectiveness of hemodialysis as well as reducing treatment time

• It stays functional for longerfunctional for longer than other access types; in some cases a well-formed fistula can last for decades

• Fistulas are usually less expensiveless expensive to maintain than synthetic accesses

INDICATIIINDICATII

DIALIZA

• IRC – UREMIE• Creatinina serica >4 mg/dL• Cl Cr <25 mL/min

NKF-DOQI clinical practice guidelines for vascular access. Am J Kidney Dis 1997; 37 Suppl 1: S150−S191.

ETAPEETAPE

• Montarea fistulei AV de catre echipa chirurgicala

• Maturarea fistulei (2-4 luni)

• Canularea fistulei de catre personalul ce deserveste serviciul de dializa

• Mentinerea fistulei patente pe termen lung

Diagrams of the three types of upper arm arteriovenous fistulas used for hemodialysis

Stepansky F et al. Radiographics 2008;28:e28-e28

Fig.  Diagrams of the three types of upper arm arteriovenous fistulas used for hemodialysis A. Normal anatomy of the right antecubital fossa, showing the cephalic vein (CV), median antecubital vein (MACV), basilic vein (BV), brachial artery (BA), radial artery (RA), and ulnar artery (UA).B. Brachiocephalic arteriovenous fistula. C. Brachiobasilic arteriovenous fistula. D. Brachial artery–to–median antecubital vein arteriovenous fistula.

Brachiobasilic

transposition

A-V fistula 

Brachiocephalic A-V fistula 

Radiocephalic A-V fistula

Brescia - Cimino

NKF-DOQI Clinical Practice Guidelines for Vascular NKF-DOQI Clinical Practice Guidelines for Vascular

Access New York, National Kidney Foundation, 1997Access New York, National Kidney Foundation, 1997

Fistula versus graft survival in patients starting hemodialysis with a permanent vascular access comparing DOPPS results from Europe and United States.

HemodinamicaHemodinamica

• Q in AB = 85 mL/min

• Fistula = Q se amplifica de aprox. 10 ori

Utilitatea US la initierea Utilitatea US la initierea Fistului A-VFistului A-V

• Masurarea Diametrului AB /AR – predictibila ptr. evolutia fistulei

• Masurarea Q in AB

• Masurarea Diametrului V cefalice

• Compresibilitatea V cefalice

Fistula AV radio-cefalicaFistula AV radio-cefalica

(A) B-mode sonogram showing a longitudinal section of an

arteriovenous fistula created by anastomosing the cephalic vein (V) to the radial artery (A) at the wrist

in a side-to-end fashion. (B) With the same sectional view,

Color Doppler sonography shows turbulent flow at the a-v

anastomosis. The radial artery (A) is feeding the shunt vein (V).

DopplerDoppler

The typical effect of an arterio-venous fistula on the Doppler tracings is shown on this diagram. The inflow artery can show a low resistance pattern due to the low resistance outflow into the vein. The bigger the effective fistula, the more diastolic flow is seen. The arterial waveform distal to the fistula regains a more typical appearance. The communicating channel and the vein close to the channel show an arterialized signal and a broad frequency range of signals

Fistula AV - Doppler Fistula AV - Doppler colorcolor

Semin Dial. 2001 Sep-Oct;14(5):314-7.The clinical utility of Doppler ultrasound prior to arteriovenous fistula creation

Brimble KS, Rabbat CG, Schiff D, Ingram AJ.

AbstractArteriovenous fistula (AVF) is the preferred access for long-term hemodialysis, with superior long-term patency rates; however, early failure rates are significant.

Recent evidence has brought into question the preferred site of AVF creation in many patient groups. A preoperative test that could reliably predict the outcome of a proposed AVF would be of great benefit.

Doppler ultrasound has been the most extensively studied and widely used test to Doppler ultrasound has been the most extensively studied and widely used test to guide access creation. Accurate and validated measurements of internal vessel guide access creation. Accurate and validated measurements of internal vessel diameter, both arterial and venous, and blood flow in the upper extremity are diameter, both arterial and venous, and blood flow in the upper extremity are obtainable by Doppler ultrasound.obtainable by Doppler ultrasound.

Studies evaluating the utility of Doppler ultrasound prior to AVF creation suggest that vessel size and blood flow are predictive of AVF outcome.

An AVF created using a cephalic vein and/or radial artery smaller than 1.5-2.0 mm is likely to fail; such preoperative data may indicate that an upper arm AVF should be the primary access attempted.

Predictori ai evolutiei Predictori ai evolutiei fistulei A-Vfistulei A-V

evaluare Doppler preoperator

• D arterial <1.5 mm

• D venos <2.5 mm

• IR > 0.8

COMPLICATIICOMPLICATII

• Bacteriemie/infectie

• Stenoza

• Tromboza

• Malfunctie

Rolul US in Rolul US in supravegherea supravegherea

fistului AVfistului AV

• Malfunctia fistulei = reducerea Q fistulei <120 mL/min

• Stenoza• Tromboza• Anevrism/Pseudoanevrism

Stenoza fistuleiStenoza fistulei

The typical blood flow velocity in a dialysis access is in the 200 cm/sec range. This dialysis access fistula shows a decreased blood flow velocity (less than 100cm/sec). The waveform has a typical appearance, showing evidence of turbulence as witnessed by the shaggy contour of the waveform. Turbulence is manifest by a random fluctuation of the peaks seen in the spectral tracing from millisecond to millisecond

PseudoanevrismPseudoanevrism

There is evidence of a large hematoma (white arrows) surrounding the access graft (color channel). This makes insertion of the needles needed to perform dialysis very difficult.

Hemodynamic changes in the early Hemodynamic changes in the early phase of artificially created phase of artificially created

arteriovenous fistula: color Doppler arteriovenous fistula: color Doppler ultrasonographic findingsultrasonographic findings

Color Doppler ultrasonography is a very effective method in the evaluation of hemodynamics of arteriovenous fistulas in hemodialysis patients. It will allow an understanding of the pathology in nonfunctioning fistulas or of the cause of complications that develop secondarily.

K. Mahmutyazicioglu, et al. Journal of Ultrasound in Medicine, 1997;16,12: 813-817

Pietura R et al. Eur J Radiol 2005;55:113-119Colour Doppler ultrasound assessment of well-functioning mature

arteriovenous fistulas for haemodialysis access

The mean flow volume was 1204.1 ml/min (S.D. = 554).

It was significantly higher in the fistulas with aneurysms, calcifications and tortuous vessels and lower in those with stenosis.

There was no correlation between the flow volume or presence of stenosis and fistula age.

Stenosis was detected in 64% fistulas. Fifty-seven percent of stenoses were located in the anastomotic region, 22% stenoses were in vein junction, 19% were at one or both ends of aneurysm, and 2% in the remaining region of the efferent vein.

Perivascular colour artefacts were present at the 94% fistulas with stenosis. Chronic venous occlusion with collateral veins was detected in 6% of fistulas.

The aneurysms were observed in 54% fistulas. The mean diameter of aneurysms was 12.4 mm. Ninety-six percent of aneurysms were located at puncture sites.

Ten patients had a small thrombus in an aneurysm and at puncture sites.

Hemodialysis arterio-venous fistula Hemodialysis arterio-venous fistula complicationscomplications

Stepansky F et al. Radiographics 2008;28:e28-e28

Fig.  Hemodialysis arteriovenous fistula complications.

(a) Time-resolved contrast-enhanced MR angiographic images at 6 seconds per frame demonstrate a left-side brachiobasilic hemodialysis fistula with multiple venous stenoses(arrows).

(b) Coronal postcontrast 3D T1-weighted fat-suppressed spoiled gradient-echo images reveal an additional significant finding: multiple intraluminal venous thrombi (arrowheads).

(c) Time-resolved contrast-enhanced MR angiograms in two patients with arteriovenous hemodialysis fistula complications; the patient in the left image has two venous aneurysms (arrows), and the patient in the right image has complete venous occlusion with collateral vessels present (arrowhead).

Hemodialysis arterio-venous fistula complicationsHemodialysis arterio-venous fistula complications

Stepansky F et al. Radiographics 2008;28:e28-e28

Fig.  Hemodialysis arteriovenous fistula complications. (a) Time-resolved contrast-enhanced MR angiographic images at 6 seconds per frame demonstrate a left-side

brachiobasilic hemodialysis fistula with multiple venous stenoses(arrows). (b) Coronal postcontrast 3D T1-weighted fat-suppressed spoiled gradient-echo images reveal an additional

significant finding: multiple intraluminal venous thrombi (arrowheads). (c) Time-resolved contrast-enhanced MR angiograms in two patients with arteriovenous hemodialysis fistula

complications; the patient in the left image has two venous aneurysms (arrows), and the patient in the right image has complete venous occlusion with collateral vessels present (arrowhead).

Hemodialysis arterio-venous fistula Hemodialysis arterio-venous fistula complicationscomplications

Stepansky F et al. Radiographics 2008;28:e28-e28

Time-resolved contrast-enhanced MR angiograms in two patients with arteriovenous hemodialysis fistula complications; the patient in the left image has two venous aneurysms (arrows), and the patient in the right image has complete venous occlusion with collateral vessels present (arrowhead).