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Evaluation of Arterio-venous

Fistula by Ultrasound

By

Rozina Badal Munir, M.B.B.S.

RPVI,RVT,RDMS,MSK,POCUS,FASE

Email; rozinabadal@yahoo.com

AVF

Nowadays AVF is commonly used for hemodialysis

AVF Route of choice for hemodialysis which survives

longer with few complications.

Highest prevalence rate of Chronic Kidney Disease in

developed countries

In United States there is rate of ESRD and CKD is also

very high.

In 2005, to improve the vascular access, Fistula First

breakthrough initiative(FFBI) program was introduced.

Goals are to increase AVF use in appropriate

hemodialysis patients and decrease the use of long term

catheters.

Patients on Hemodialysis

Patients quality of life

Successful & adequate hemodialysis

Quality & reliability of Vascular access

Vascular surgeons technique & choice of adequate

vessels

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Adequate for Dialysis

AVF is defined as

“Adequate for Dialysis” if

it could be cannulized

with 2 needles and could

provide dialysis blood flow

of 350 ml/min or higher in

at least 6 sessions during

one month

Maturation Of AVF

Anatomical/Physiological/

Functional/clinical

A mature AVF can be defined as one

which has undergone sufficient

anatomical & physiological changes

to be ready for repeated

cannulization and provides

adequate blood flow for dialysis.

Ultrasound Role

Preoperative:

Arterial Mapping

Vein Mapping

Intra-operative:

For access

Post-operative:

Access for maturation

Surveillance

Complication evaluation

Ultrasound is cost effective,

readily available, portable,

no radiation and dynamic.

Pre Operative:Arterial Anatomy of Upper Extremity

Left SCA Origin from Aortic Arch

Right SCA Origin from Brachiocep A

Axillary A

Brachial A

Radial A

Ulnar A

Normal High resistance

flow- Triphasic flow

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Arterial Duplex Scanning

Arterial Duplex is done to confirm presence of suspected PVD

To find anatomic location of disease or stenosis or lesions

Helps in the process of decision making

Pre-Op evaluation: Normal Arterial

Diameter from intima to intima

Perpendicular to arterial wall

Long axis

Homogenous velocities

& good filling

Arterial inflow

Wall, calcification,

IMT, depth, diameter,

stenosis,

In case of low flow, look

for stenosis or central

cause of low flow

Artery:>2mm

No stenosis, PSV>50cm/s

Normal high

resistance triphasic

flow

Reactive hyperemia

RI<0.70

Arterial Hyperemic ResponseTo predict risk of arterial steal

Clench fist (3 min): high resistance flow(triphasic)

Release fist: low resistance flow(monophasic) & RI <0.70

Failure to this response = clinical insufficiency to AVF

Doppler ultrasound of A-V access for hemodialysis ,slidshare/by Samir Haffar MD/cited from

Wiese P et al.ephrol Dial Transplant 2004: 19;1956-1963

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Palmar Arch PatencyUS improves the accuracy of Allen’s Test

Color Doppler of

palmar archRadial Artery

Compression

While

imaging arch

Reversed flow

Flow via ulnar

artery

Mozersky DJ et al.Am J Surgery. 1973

Levitov A et. Clinical care ultrasonography.McGraw-Hill Medical, NY, USA,2009

Allen’s test

Preoperative:

Venous System of Upper Extremity

Superficial Veins

Cephalic vein

Basilic Vein

Deep Venous System

SC V

Axillary V

Brachial Vs

Radial V

Ulnar V

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Pre OP evaluation

consideration-Venous

Comfortable position the arm

Copious warm gel to avoid pressure on vein

Veins are examined from wrist to distal end of clavicle

Check for spontaneity, phasicity, compressibility, lumen

echogenicity, wall irregularity and diameter

Cephalic and basilic veins

Depth from the skin, diameter

Also Venous assessment of SCV, Axillary and brachial

veins to r/o DVT

Cephalic Vein Mappingsites for mapping of CV, with and w/o tourniquet, Depth from skin

www.google.com

Normal Venous Flow

Spontaneous and phasic flow with respiration

Compression

Augmentation to check patency distally

Valsalva Patency above the site of examination

Phasic flowWith & w/o compression

Doppler ultrasound of A-V access for hemodialysis

,slidshare/by Samir Haffar MD/cited from Mihmanli I e al. J Ultrasound Med 2001: 20:21

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Pre-op Criteria:

Vein

> 2.5 mm or 3mm

Vein wall, branches

> or equal 500ml/min blood flow

Large accessory vein which may

limit the maturation of fistula

Levitov A et. Clinical care ultrasonography.McGraw-Hill Medical, NY, USA,200

Pre-op vascular mapping50 y o M Patient , scheduled for Forearm graft

Check diameter of vein and artery and depth from the skin

Radial Artery at Wrist and

antecubital area

Cephalic Vein at wrist and

antecubital area

Adequate for AVF

Doppler ultrasound of A-V access for hemodialysis ,slidshare/by Samir Haffar MD/

Example:

Fistula types

1) Brescia Cimino

Radial A and Cephalic V (most Common)

2) Upper Arm Cephalic-

Brachial A and Cephalic vein

3) Upper arm basilic transposition

Brachial A and Basilic V

Graft;

1) Loop or straight graft

2) Brachial A-Basilic , Brachial or axillary veins

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Types Of Fistula

UA Cephalic vein AVF

UA Basilic vein

Transposition AVF

FA Cephalic Vein AVF

Rad-CephBrach-Ceph

Brach-Bas

Trsp

AVF Anatomy

3 Main segments of AVF

Inflow Artery

Fistula Vein

Outflow Vein

Main components of Inflow Artery

Proximal to Anastomosis

Distal to Anastomosis

Prx to Anastomosis

Distal to Anastomosis

AVF anatomy

Inflow Artery

Radial Artery

Ulnar Artery

Brachial Artery

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AVF Anatomy

Fistula Vein

-Arterial Anastomosis

-Usable segment

-Venous end and

confluence

Fistula Vein

-Cephalic Vein

-Basilic Vein

-Median Vein

AVF Anatomy

Outflow Vein

-Proximal to AVF

-Distal to AVF

USG Technique post op Evaluation

Use high frequency

Grayscale transverse /longitudinal

Feeding artery

Draining vein

Color Doppler

Spectral Doppler

PSV/EDV Ratio

Doppler angle<60 degree

include volume flow measurements

Evaluate from feeding artery to anastomosis

Evaluate from draining Vein as fast as possible

Perivascular space for stenosis from

abscess/hematoma/seroma

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Maturation of AVF(Sonographic measurement) KDOQI rule of 6

External Diameter>/= 0.6cm

Not more than 0.6 cm deep

from skin surface

Blood flow volume

is>600ml/min

10cm straight length of fistula vein

No competing branches

National Kidney Foundation Recommendations of NKF-KDOQI

Kidney Disease Outcomes Quality Initiative criteria KDOQI US Commentary on the 2017 ACC/AHA Hypertension Guideline - American

Journal of Kidney Diseases

Flow Volume Measuring Tips

TAMV-Time Averaged mean Velocity: V mean cm/s

(Auto calculation feature)

Technique:

-Study done on non dialysis day

-Measure intima to intima distance(lumen diameter)

-Measure velocity 2-4 cm from anastomosis, straight

segment

Take mean of 3 readings

Scanning of AVF- Prx to AVF

1) Inflow artery-prox to anastomosis-Gray scale- Stenosis, Calcificaions, thrombus

-Color Doppler- Direction of flow

-Spectral Doppler- Velocity, flow volume and

type of waveform

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Scanning of AVF-Distal to anastomosis

Inflow artery - distal to

anastomosis

-Color Doppler- Direction of flow

-Spectral Doppler- Type of

waveform

Normal Mature Fistula

Artery cranial to Anast

No gradient between the two readings

Scanning of AVF

Fistula Vein

Arterial Anastomosis

Usable Segment

Venous end

Venous Confluence

Fistula Vein

Gray scale, color / spectral Doppler

-Flow Volume

- Depth and transverse

measurement

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Scanning of AVF-Outflow Vein

Grey Scale, color and spectral Doppler

Normal mature fistula

Draining Vein

Anastomosis

First hemodynamic change

after AVF creation is

increased in blood flow

volume in the inflow artery

and Fistula vein due to

creation of low resistance

outflow(thus providing

adequate flow to dialysis

machine).

Increased flow volume

causes two anatomical

changes, increased

diameter and wall

thickening in Fistula vein,

due to factors, shear wall

stress(diameter) and hoop

stress(wall thickness)

Time: 4-6 weeks post-op

Volumetric flow >600 ml/min

Normal mature fistula-good distal flow

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AVF Maturation

Well functioning AVF=700-1300ml/min

Values < 500ml/min = Access dysfunction

Values<300ml/min = imminent thrombosis

Previously functioning AVF with >1000

ml/min flow volume, if there is decrease

of >25% over a short period of time,

further investigation is required

Contraindications

No absolute CI in performing exam

Open wounds

Recent surgery

Scar tissue

Calcifications

Severe edema

Contractures

Other reasons for immobility

Causes of fistula failure

30- 50% fistulas fail to mature

Arterial:

Artery unable to deliver adequate blood flow

•Inflow artery small caliber or Stenosis

•Stenosis at anastomotic site

Venous;

•Outflow venous stasis

•Branches

•Vein unable to dilate

•Atretic vein due to chronic thrombosis

•Deep vein

•hematoma

Immature fistula can be converted into usable

fistula with correction of underlying problem

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Competing Accessory Vein

More common in Forearm fistulas

Significant when large vein is present in 10 cm from AV anastomosis

Sudden change in calibre of outflow vein at this level

This shows that large vein is stealing blood from fistula vein and

preventing maturation of fistula

Flow volume is decreased

When a vein is coming out of the fistula is it truly competing or

secodary to outflow vein stenosis or occlusion of central vein(more

closer to heart) which causes the accessory vein to enlarge

Dialysis Fistulas and Grafts - Gowthaman Gunabushanam, MD #694 Released On : 01/06/2019, The

Society of Radiologists in Ultrasound (SRU)

Immature Fistula

Detected lesions in sonographically immature fistulas

Stenosis 35% Most common site is anastomosis

Vein branch 52%

Too deep 29%

Multiple lesions 20%

Management:

Always mention the distance of stenosis from the

anastomosis for helping the surgeon

Angioplasty , coil embolization, or surgical revision

Stenosis Criteria

Gray scale US narrowing, lumen <3mm

PSV Ratio at anastomosis > 2 suggests 50% stenosis

PSV > 400cm / sec

Flow volume <600ml/min in outflow vein

Mid outflow vein velocity PSV < 100cm/s

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Immature fistula V . Flow

<600cc/min

PSV Ratio at anastomosis>3

(stenosis)

Draining Vein Stenosis

PSV ratio > or equal suggests 50 -74%

PSV ratio > or equal suggests > or equal 75%

It is important to connect dilated vein to

anastomosis

High pressure collaterals may confuse

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DV stenosis

DV stenosis

DV stenosis

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DV stenosis

DV stenosis

DV stenosis

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DV occlusion

Monophasic central flow

Bilateral SCV monophasic

flow-Central occlusion

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Benefits of Native Vs Graft AVF

Reduced morbidity & mortality

Superior patency rates

Lower rates of thrombosis

Longer hemodialysis access survival rates

Lower infection rates

Lower hospitalization rates

Lower cost

Types of AV grafts

Upper Arm Straight Graft

Radial A to Ax vein

Fore arm Loop Graft

Brachial A to Brachial Vein

Journal of vascular surgery 2011.

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Grafts

Grafts mature in 2-3 weeks

In AVG (Arterio venous Graft) : flow volume in brachial

artery (>90 % of flow is through AVG)

Stenosis is usually venous as veins not meant for high

pressure

Pre-op AVG assessment

Length of Radial and Ulnar arteries

Note plaques

Confirm compliance of vessels

Record vessel diameter and PSV, proximally and distally

www.slideshare.com/radial

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Complications;

Other complications include:

Thrombosis

Pseudoaneurysm

Aneurysm

Collection

Infection

Brachial AVG-Thrombosis

Thrombosis

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Pseudoaneurysm

Graft

Arterial Steal

5-8 % pts: pain, numbness, tingling, ulcer

Risk Factors: DM, women, advanced age, PAD

Flow reversal or bidirectional in post anastomotic

segment of artery

Digital SBP, 60 mmHG

Provocative maneuvers: compress outflow vein

- Improved flow on spectral Doppler

- Finger brachial indices, plethysmography PVR

Radial Artery StealSteal phenomenon : silent in 70 % of RC-AVF

Steal Syndrome: Mild: pain during dialysis

Severe: rest pain , ulceration common cause of neuropathy

Ulnar artery flow contributes to fistula flow via palmar arches.

Retrograde flow in distal radial artery

Doppler US: Reversed flow: complete- only in diastole

Dynamic study: gentle compression of AVF

Treatment: Ligation , banding ,rerouting

Am. J of Vascular surgery 2008 Padberg FT et al.J Vasc Surg 2008:48:55S-80S

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Radial artery steal

RC-AVF

Radial artery distal to anastomosis Compression on fistula

Restoration of antegrade flow

Elevated systolic flow

Elevated diastolic flow

Antegrade flow during systole

Retrograde flow during diastole

Bidirectional flow

Digital Ischemia from emboli of thrombosed AVF

Digital ischemia

4 finger of rt hand

Partial Thrombosis of RC-AVF Regression of

ischemia

6 mo post op

Doppler ultrasound of A-V access for hemodialysis ,slidshare/by Samir Haffar MD/Department of Internal

Medicine/Al-Mouassat University Hospital-Damascus-Syria

Complications of AVF-StealCompression of AVF should show flow reversal and change

of waveform from low resistance to high resistance

Normal

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Complications of AVF

Fluid Collections:

Edema,Hematoma,

seroma, peri-fistula

fluid

Usually seen close to

surgical scar but may

expand through fascial

planes.

Sonographically , from

clear anechoic to complex

to organized hematoma.

Complications of AVF

Aneurysm/Pseudoaneurysm

More common in graft than

native AVF

Aneurysm is >1.5 greater

than normal segment.

(Per KDOQI)AVF should be

revised when PSA develops

due to risk of fistula rupture

Puncture sites are limited

due to large or multiple

PSA.

Infection, pain and

throbbing .

Complication of AVFAneurysmal dilatations are not a problem until: 2cm in diameter,

vey thin wall and contain thrombus

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Complications of AVF:Stenosis

Stenosis can occur anywhere:

-Inflow artery

-Fistula vein at arterial or venous end

-Outflow and central venous system

Summary

Inflow artery prox to AVF

Inflow Artery distal to AVF

Useable segment

Venous end/Outflow vein

THANK YOU

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Resources: KDOQI US Commentary on the 2017 ACC/AHA Hypertension Guideline - American

Journal of Kidney Diseases

Dialysis Fistulas and Grafts - Gowthaman Gunabushanam, MD #694 Released On :

01/06/2019,www.sonoworld.com

Ultrasound Evaluation of Complications - Post Arterial Interventions - Nirvikar Dahiya,

MD #520 Released On : 10/23/2016

Upper Limb Arterial Doppler - Nitin Chaubal, MD #424 Released On : 01/18/2015

Doppler ultrasound of A-V access for hemodialysis ,slidshare/by Samir Haffar

MD/Department of Internal Medicine/Al-Mouassat University Hospital-Damascus-Syria

Mozersky DJ et al.Am J Surgery. 1973

Levitov A et. Clinical care ultrasonography.McGraw-Hill Medical, NY, USA,2000

National Kidney Foundation/ Kidney Disease Outcomes Quality Initiative(KDOQI)/National Kidney

Foundation Am. J Kidney Dis 2006

Journal of vascular surgery 2011

Padberg FT et al.J Vasc Surg 2008:48:55S-80S

Role of Sonography in the Evaluation of Native AVF and its Complications, Jawed Shaikh

www.aium.org

References KDOQI, “Clinical practice guidelines for vascular

access,” American Journal of Kidney Diseases, vol. 48,

supplement 1, pp. S176–S247, 2006. View at

Publisher · View at Google Scholar · View at Scopus

NKF-DOQI, “NKF-DOQI clinical practice guidelines for

vascular access,” American Journal of Kidney Diseases,

vol. 30, no. 4, supplement, pp. S150–S191, 1997. View

at Google Scholar · View at Scopus

L. Kumbar and J. Karim, “Besarab; Surveillance and

monitoring of dialysis access,” International Journal of

Nephrology, vol. 2012, Article ID 649735, 9 pages,

2012. View at Publisher · View at Google Scholar

W. D. Paulson, L. Moist, and C. E. Lok, “Vascular access

surveillance: an ongoing controversy,” Kidney

https://www.hindawi.com/journals/ijn/2012/508956/

https://www.kidney.org/sites/default/files/KDOQI-HD-

update-NRAA-2016_FINAL.pd

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