Haemodialysis fistula

1. DOPPLER EVALUATION OF
HAEMODIALYSIS FISTULA
Dr. Sharoj Khan
MDRD Resident
NMCTH

2. INTRODUCTION
• An acquired arm arteriovenous fistula (AVF) creation is a procedure performed for haemodialysis
access in those with end stage renal failure.
• It connects artery to a vein.
• This can either be a native connection or a connection using a PTFE (polytetrafluoroethylene) graft.
• Mature AVFs are the preferred access when appropriate, because of the lower rates of infection
and thrombosis than with graft or catheter access.
• Preoperative ultrasound evaluation of the upper extremity veins and arteries increase the number
of successful AVF placements through optimization of surgical plannings as well as before graft
placement in the thigh.

3. • Postoperative hemodialysis access evaluation is beneficial in assessing AVF maturation, the role of
postoperative ultrasound evaluation for the detection of pathology and is early intervention to
improve the longevity.
• Ultrasound is useful in evaluation of palpable masses adjacent to the vascular access to differentiate
hematoma from pseudoaneurysm.
• US is also used in the evaluation of the swollen upper extremity in a patient with an AVF or graft, or a
swollen lower extremity in a patient with a thigh graft, assessing for outflow vein stenosis and DVT

4. • The surgical creation of an AVF is preferred over a graft when surgically and clinically feasible.
• Placement of access in the non-dominant upper extremity is preferred to allow continuance of
daily activities of life while the access site heals; however, a dominant arm AVF is preferred to a
graft in most patients.

5. • Possible sites of hemodialysis access in order of preference are as follows:
(1) forearm AVF (radiocephalic AVF or transposed forearm basilic vein to radial artery AVF);
(2) upper arm brachiocephalic AVF;
(3) transposed brachiobasilic AVF;
(4) forearm loop graft;
(5) upper arm straight graft (brachial artery to upper basilic or axillary vein);
(6) upper arm axillary artery to axillary vein loop graft; and
(7) thigh graft

6. (A) Forearm cephalic vein–radial artery AVF. (B) Upper arm cephalic vein–brachial artery AVF, using the median
cubital branch of the cephalic vein for the anastomosis. (C) Upper arm basilic vein–brachial artery AVF.

7. . (D) Forearm loop graft. (E) Upper arm straight graft. (F)
Upper arm loop graft.

8. (G) Thigh loop graft.

9. VASCULAR MAPPING BEFORE HEMODIALYSIS ACCESS
• The patient should be sitting upright for optimal evaluation of the upper
extremity arteries and veins, with the forearm resting comfortably on a table
or armrest.
• A tourniquet should be placed after arterial assessment, to assess vein
caliber and distention.
• Central venous evaluation to include the IJV and subclavian vein should then
be performed with the patient supine, for easier and potentially more
accurate waveform assessment.
• assessment of the arterial wall should evaluate the amount of calcification
and degree of stenosis or occlusion, if present.
• Vein walls should be described with as much detail as possible to assess for
wall thickening and thrombus, which may limit future venous distention

10. • Preoperative criteria include a minimum intraluminal arterial diameter of
2.0 mm and a minimal intraluminal venous diameter of 2.5 mm to allow
successful AVF creation, and a minimum intraluminal venous diameter of
4.0 mm and a minimum arterial diameter threshold of 2.0 mm for grafts.
• The arterial waveform is evaluated for a normal triphasic or biphasic
high-resistance flow pattern, and PSV is measured in these regions

11. Preoperative Mapping Ultrasound Meeting Criteria for Arteriovenous Fistula
(AVF) Placement. (A) Arterial evaluation: radial artery diameter of 0.28 cm
(cursors). (B) Mild medial calcification in arterial wall (arrows) does not
preclude AVF placement. (C) Normal triphasic radial artery spectral
waveform.

12. • A high brachial artery bifurcation is a common anatomic variant and
should be suspected when two arteries with accompanying paired veins
are seen in the upper arm
The two arteries should be followed into the forearm to the wrist to confirm the presence
of a high brachial artery bifurcation and to exclude a prominent arterial branch supplying
the elbow, less commonly seen.
High Brachial Artery Bifurcation. Radial and ulnar arteries
(A) and accompanying paired veins (V).

13. • For assessment of veins, the upright-seated position ensures venous distention owing to hydrostatic pressure.
• For optimal venous distention, the tourniquet should be placed on the arm cranial to the area of interrogation so tha
the veins are distended. Each vein should be inspected, with compression performed along the entire venous length
to exclude thrombus.
• The tourniquet is first placed in the midforearm.
• The region of the cephalic vein at the wrist is percussed for about 2 minutes for maximal venous distention, and the
cephalic vein inner diameter is measured at multiple points in the forearm.
• Thereafter, the tourniquet is placed at the antecubital fossa, and then the proximal upper arm, after segmental vein
diameter measurement.
• Cephalic vein anterior wall distance from the skin can be measured because if the cephalic vein is too deep for easy
cannulation, it may need to be superficialized in a subsequent surgery.
• It is not necessary to measure the distance of the basilic vein from the skin; the vein needs to be transposed for easie
access. The median antecubital vein typically connects the cephalic vein to the basilic vein and is often part of the AV
draining vein.
• The median antecubital vein also can be used in creating an upper arm basilic or cephalic vein AVF and so is
commonly evaluated at the mapping ultrasound procedure.

14. • The axillary vein, subclavian vein, and IJV should be assessed for
compressibility (when possible) and normal waveforms

15. ULTRASOUND EXAMINATION AND
IMAGING PROTOCOL
• Upper Extremity.
• After assessment of the brachial and radial arteries, the inner luminal diameter of the brachial artery 2 cm
proximal to the antecubital fossa, and the radial artery at the wrist are measured, along with the axillary
artery diameter.
• Using sequential tourniquet placement and after wrist percussion of the cephalic vein region, the cephalic
vein inner diameter is measured at the wrist, midforearm, and proximal forearm (approximately 4 cm from
the antecubital fossa).
• The proximal forearm measurement is used to evaluate the length of vein available to surgically move the
vein from the forearm to the brachial artery in upper arm AVF creation.
• The cephalic and basilic vein diameters are measured at the antecubital fossa and mid and cranial upper arm.
• Distance of the anterior wall of the cephalic vein to the skin surface is measured.
• The axillary vein diameter is measured. The subclavian vein and IJV are assessed in the longitudinal plane
with color and spectral Doppler assessment, and IJV compression is performed to assess for thrombus,
stenosis, and occlusion.
• Subclavian and internal jugular spectral Doppler waveforms are assessed for respiratory phasicity and
transmitted cardiac pulsatility

16. • Thigh
• Used when AVF and grafts in the upper extremity are exhausted.
• Thigh grafts are similar to upper extremity grafts in length of time to permanent failure, with a trend
increased loss because of infection.
• Thigh grafts are superior to dialysis via a catheter.
• If heavy arterial common femoral or superficial femoral arterial calcification is found at ultrasound,
may be useful to determine the degree of atherosclerotic disease present.
• Careful sonographic assessment of atherosclerotic calcification and stenosis may limit immediate graft
at surgical placement.
• Thigh graft creation has typically been at the common femoral artery and vein.
• Spectral and color Doppler evaluation of the common femoral artery and vein are performed to evaluate for
more proximal stenosis or occlusion. SFA waveforms are also assessed for normalcy.
• The length of the GSV, which is at least 0.4 cm inner diameter, is measured from its insertion into the CFV
extending distally. Inner diameter measurements of the proximal and mid superficial femoral artery and FV are
obtained. Compressibility of the veins assessing for thrombus and wall thickening is performed.
• An alternate place to anastomose the venous end of the graft is the GSV, to preserve the CFV when graft
revision is necessary. However, to preserve proximal vasculature for graft revision, and potentially because of
fewer infectious complications, midthigh grafts are now being increasingly placed in the mid SFA and superficial
femoral vein.

17. Thigh Graft Preoperative Mapping. (A) Heavy arterial calcification is seen in the common femoral artery (CFA; *) with
normal common femoral vein compression (compression not shown). (B) Longitudinal view of the mid superficial
femoral artery (SFA) also shows heavy arterial calcification. (C) Spectral Doppler waveform of the mid SFA does not
have a normal triphasic or biphasic waveform. These arteries may be too heavily calcified to sew into, and would likely
prompt further evaluation of the patient’s arterial inflow to assess whether thigh graft placement is possible in this
patient.

18. ARTERIOVENOUS FISTULA AND GRAFT
• Operative notes and pertinent patient history should be reviewed before sonographic evaluation of
hemodialysis access.
• An overall ultrasound scan is performed initially to obtain an overview of the access anatomy and
anastomoses.
• When the general layout is known, sonographic assessment is performed with duplex Doppler sonography,
typically in a seated patient with his or her arm resting comfortably on a table.
• The caudal third of the feeding artery is assessed for stenosis, and the intraluminal diameter is measured in
the transverse plane using gray-scale techniques.
• The feeding artery is further assessed with color and spectral Doppler in the longitudinal plane to
document normal low-resistance flow.
• Measurements of PSV and EDV can be obtained in the feeding artery, and at least at the anastomosis(es).
There may be multiple anastomoses in the case of a graft.
• The draining vein of the AVF or graft is inspected for wall thickening, stenosis, and thrombosis along its
entire length.

19. Normal Mature Forearm Arteriovenous Fistula (AVF) Ultrasound Evaluation (Radial Artery at the Wrist to Cephalic
Vein). (A) Normal feeding artery internal diameter (cursors). (B) Color and spectral Doppler 2 cm upstream to the
anastomosis measures 2.62 m/sec. (C) peak systolic velocity (PSV) measures 3.97 m/sec for a PSV ratio at
anastomosis of less than 3:1, normal. Visual assessment of anastomosis is also normal, without stenosis. (D) Normal
cephalic vein cranial to the anastomosis (cursors show internal diameter measurement). (E) Mid AVF draining vein
volume flow rate measurement (in midforearm) is 1000 mL/min.

20. • If a stenosis is seen, the highest PSV either within the stenosis or in the jet downstream from the stenosis
is measured, using angle correction parallel to the jet if different from the angle with the posterior
vascular wall, keeping the angle to 60 degrees or less.
• The PSV 2 cm upstream to the stenosis is measured, and a PSV ratio of the PSV at the stenosis divided by
the upstream PSV is calculated.
• A longitudinal gray-scale image is obtained to document any intraluminal thrombus identified within a
draining vein or graft.
• Duplex Doppler should be performed to confirm absence of flow, with use of the more sensitive power
Doppler as needed.
• Terminology including cranial and caudal location with regard to a particular anastomosis, and upstream
or downstream position, may be more useful than the conventional proximal and distal terminology.

21. ARTERIOVENOUS FISTULA
• The feeding artery luminal diameter is measured. Spectral and color Doppler evaluations of the
feeding artery are performed to evaluate for arterial stenosis or occlusion.
• The anastomosis is assessed for visible narrowing with subsequent spectral and color Doppler
evaluation.
• The AVF draining vein diameter is evaluated at several levels from the anastomosis to 15 cm cranial to
the anastomosis.
• The intraluminal draining vein diameter and the depth of the vein from the skin surface are measured
at several points cranial to the arteriovenous anastomosis.
• Access challenges may result with a depth greater than 5 to 6 mm and require superficialization.
• The draining vein is interrogated for accessory branches.
• Intraluminal diameter and distance from the anastomosis are recorded for each identified accessory
vein within 10 to 15 cm of the anastomotic site.

22. • The flow volume rate measurements are obtained within the midportion of the draining vein of
an AVF, typically at 10 cm cranial to the anastomosis.
• Optimal flow volume measurement is obtained in an area with parallel vessel walls, minimal
vessel tortuosity, and no stenosis

23. GRAFT
• A normal graft is seen as two echogenic lines that represent strong
specular reflection from polytetrafluoroethylene material.
• A low-resistance flow (arterialized flow) should be seen within a graft.
Duplex Doppler evaluation of the feeding artery (including luminal
diameter), arterial-graft anastomosis, graft (arterial side and venous side
if loop graft), and venous anastomosis is performed, as well as draining
vein and central vein evaluation.
• Flow volume is assessed within the midgraft and both arterial and
venous limbs if a loop graft. Any points of visible narrowing are further
assessed with spectral and color Doppler.

24. Assessment of Upper Arm Graft (Brachial Artery to Axillary
Vein Graft) With Peak Systolic Velocity (PSV)
Measurement. (A)
Normal color and spectral Doppler images show artery
feeding the graft 2 cm cranial to the arterial anastomosis;
PSV measures 3.7 m/sec.
(B) Arterial anastomosis: PSV is 5.98 m/sec. PSV ratio is
<3:1, normal, corroborating with no visual stenosis.
(C) Midgraft body. No abnormal area of
stenosis is seen.
D) Flow volume rate measurement of 601 mL/min in
midgraft. (E) Within the graft, 2 cm upstream from venous
anastomosis,
PSV measures 2.09 m/sec.
(F) At the venous anastomosis, PSV measures 2.47 m/sec.
PSV ratio is <2:1, normal, corroborating with no visual
anastomotic stenosis.

25. PALPABLE FOCAL MASSES NEAR ARTERIOVENOUS FISTULA
AND GRAFT
• Hematoma: Avascular, hypoechoic lesions adjacent to the AVF or graft often represent postaccess or
postprocedure hematomas
Large Hematoma Adjacent to Arteriovenous Fistula (AVF).
Gray-scale image shows hematoma (calipers). No flow was
seen on color or spectral Doppler (not shown). See also
Video 27.26 for adjacent patent AVF.
Fluid collections with echogenic foci associated with
shadowing suspicious for gas may represent abscess in
certain clinical settings.

26. • Aneurysm and Pseudoaneurysm: Focal or diffuse aneurysmal dilation of
the AVF draining vein may occur as a result of repeated puncture.
• Pseudoaneurysms may develop within a fistula or graft and often are
related to suboptimal compression after cannulation.
• Color Doppler of a pseudoaneurysm reveals a circular flow pattern
termed “yin-yang”
Helical Flow in the Aneurysmal Dilation of
Arteriovenous Fistula (AVF). (A) Aneurysmal
dilation of the AVF draining vein in the area of
palpable swelling. No pseudoaneurysm seen. (B)
“Yin-yang” flow pattern on color Doppler due
to swirling blood.
Small Basilic Vein Pseudoaneurysm. (A) Basilic
vein arteriovenous fistula (*) with
pseudoaneurysm (arrows). (B) Spectral Doppler
in the pseudoaneurysm neck shows typical “to-
and-fro” pattern

27. ARTERIOVENOUS FISTULA MATURATION
EVALUATION
• A 6-week postoperative AVF ultrasound is used in some clinical centers
for routine evaluation of the AVF to determine its development toward
usability.
• A functioning AVF has a volume flow of at least 300 to 800 mL/min.
• when an AVF had a minimum draining vein of 4 mm or larger or a blood
flow rate of 500 mL/min or higher, approximately 70% of AVFs were able
to be used for hemodialysis.
• Sonographic criteria published by the National Kidney Foundation
Kidney Disease Outcomes Quality Initiative suggestive of maturation
include a draining vein greater than 6 mm diameter, blood flow rate
greater than 600 mL/min, and less than 6 mm skin depth.

28. ARTERIOVENOUS FISTULA AND GRAFT
STENOSIS
• AVF: Stenoses associated with AVFs are most frequently juxta-
anastomotic, followed in frequency by AVF draining vein, with central
venous and feeding artery stenosis less common but not infrequent.
• Stenoses may be clinically relevant owing to resultant flow decrease and
can be associated with subsequent thrombosis.
• Potential sites for AVF stenosis include the feeding artery, juxta-
anastomotic region, draining vein, and central veins.
• Early after placement, juxta-anastomotic stenoses are the most common.
Later, AVF draining vein and central vein stenoses are more common,
including a “cephalic arch” stenosis in which the cephalic vein enters the
subclavian vein in the cephalic vein AVF.
• Fistula stenosis is characterized by two criteria:
• (1) visual narrowing of greater than 50% as assessed on gray-scale imaging,
and
• (2) an elevated PSV ratio of the PSV at or just distal to the stenosis as
compared with the PSV measured 2 cm upstream from the site of stenosis.

29. • A juxta-anastomotic stenosis is defined by a location within 2 cm of the anastomosis, encompassing
both the feeding artery and the draining vein.
• The juxta-anastomotic stenosis will show visible narrowing and a PSV ratio of greater than or equal to
3 : 1
• A draining vein stenosis is defined by visible narrowing and a PSV ratio of 2 : 1 identified within the
draining vein 2 cm cranial to the anastomosis.
• Feeding artery stenosis greater than 2 cm proximal to the anastomosis is uncommon; these are
characterized by a PSV ratio of 2 : 1 with visible narrowing.
• Poststenotic waveforms show delayed systolic upstrokes that may suggest proximal arterial stenosis
and prompt further direct evaluation of the feeding artery more cranially.

30. Arteriovenous Fistula (AVF) JuxtaAnastomotic Stenosis. (A)
Peak systolic velocity (PSV) measurement in the feeding
artery 2 cm upstream (cranial) to the anastomosis. PSV, 2.4
m/sec. (B) PSV measurement at anastomosis is 7.5 m/sec,
for a PSV ratio of >3:1, consistent with juxta-anastomotic
stenosis. (C)-(F) In another patient, (C) juxta-anastomotic
stenosis (arrow) with vein narrowing approximately 1 cm
from anastomosis. *, Anastomosis; A, feeding artery. (D)
Poststenotic draining vein dilation (arrows) downstream
from the stenosis. (E) Color Doppler shows marked aliasing
at the stenosis. (F) Spectral Doppler measurement of
stenosis is 6.7 m/sec. (G) Spectral Doppler measurement 2
cm upstream in the brachial artery measures 1.24 m/sec,
for a PSV gradient of >3:1, concordant with visual

31. 7 Graft or Arteriovenous Fistula (AVF) Draining
Vein Stenosis Assessment Using Color and Spectral
Doppler With Peak Systolic Velocity (PSV) Measurement.
(A) Visual narrowing in draining vein greater than 2 cm
downstream from anastomotic stenosis (therefore draining
vein stenosis, not juxta-anastomotic stenosis). (B) PSV
measurement of area of greatest narrowing is 8.5 m/sec.
(C)
PSV 2 cm upstream from draining vein stenosis is 3.4
m/sec
for a PSV gradient of >2:1, with visual narrowing,
consistent
with at least 50% stenosis.

32. • Graft: Graft abnormalities are similar to those described earlier for AVF, with differing diagnostic thresholds and
criteria. Several studies have indicated that grafts with decreased blood flow are at increased risk for thrombosis.
• The four sonographic criteria used to characterize graft stenosis are
• (1) luminal narrowing on gray-scale imaging,
• (2) a high velocity jet on color Doppler,
• (3) a PSV ratio greater than 2 : 1 for the venous anastomosis or draining vein, and
• (4) a PSV ratio greater than 3 : 1 for the arterial anastomosis.
• The most common site of graft stenosis is the venous anastomosis. Other, less frequently used sites are the
draining vein, intragraft region, arterial anastomosis, and central veins.

33. Graft Venous Anastomotic Stenosis. (A) Gray-scale image
shows significant narrowing at thigh graft– common
femoral vein anastomosis. (B) Venous anastomosis peak
systolic velocity (PSV) measures 6.1 m/sec in greatest jet.
(C) PSV measurement within the graft 2 cm upstream from
the venous anastomosis is 2.53 m/sec, for a PSV ratio >2:1,
and concordant with visual narrowing, consistent with at
least 50% stenosis.

34. ARTERIAL STEAL
• Arterial steal is defined as flow reversal in the native artery caudal to the anastomosis and
may be asymptomatic, or associated with clinical findings such as hand pain and
paresthesias that can worsen during hemodialysis.
• In severe cases, ischemia or tissue necrosis of the fingers can occur. Sonographic
evaluation may show reversal of flow in the distal artery, and rarely shows an arterial
occlusion.
• Brief manual compression of the graft can demonstrate a change in the reversed arterial
flow, producing an antegrade high-resistance flow pattern toward the hand.
• It is important to note that asymptomatic flow reversal in the artery downstream from the
arterial anastomosis is frequently seen, particularly in the AVF. In severe cases of arterial
steal, surgical revision may be necessary.

35. Arterial Steal in a Radial Artery to Cephalic Vein
Arteriovenous Fistula (AVF) in the Proximal Forearm. (A)
Grayscale image of anastomosis shows no stenosis. A,
Feeding artery; V, draining AVF vein. (B) Reversal of flow
direction is seen in the radial artery just caudal (distal to
the AVF anastomosis) in the radial artery—arterial steal. (C)
Reversal of flow in the distal radial artery at the wrist
confirms arterial steal.

36. ARM AND LEG SWELLING WITH ARTERIOVENOUS
FISTULA OR GRAFT
• When there is upper extremity swelling associated with an AVF or graft, the ipsilateral axillary, subclavian
vein, and IJV should be included in the postoperative sonographic evaluation.
• Occasionally, a DVT of the brachial, axillary, or subclavian vein is the cause of arm swelling in a patient with
an AVF or graft. If an upper extremity DVT is not found, spectral Doppler imaging of the IJV and subclavian
vein may provide indirect evaluation of the brachiocephalic veins.
• monophasic venous waveforms of the subclavian vein and IJV suggest central venous stenosis or occlusion.
• The absence of phasicity in the central veins is less specific for central venous occlusion in patients with a
graft than in patients with an AVF because of the larger blood flow volume rate within grafts.
• Findings suggestive of central stenosis or occlusion are visible narrowing, focal turbulence, focally elevated
velocity, and collaterals.
• If a central stenosis or occlusion is suspected, central vein assessment with magnetic resonance imaging
(MRI) or venography may be useful because a central stenosis severe enough to cause arm swelling may be
present despite adequate or high AVF flow

37. Severe Subclavian Vein Stenosis. (A) Monophasic flow in
the medial subclavian vein does not return to baseline. (B)
Monophasic flow in the caudal internal jugular vein does
not return to baseline. (C) Severe stenosis in proximal
subclavian vein confirmed at venography before
angioplasty.

38. ARTERIOVENOUS FISTULA AND GRAFT
OCCLUSION
• Access occlusion can be determined by physical examination. However,
in the case of significant arm swelling or an inexperienced examiner,
ultrasound evaluation may be useful.
• Thrombosis can be visualized within the vessel lumen on gray-scale
imaging and confirmed by lack of color or spectral Doppler flow within
the affected portion of the AVF, graft, or draining vein.
• Slow flow may be identified with power Doppler when nonocclusive
thrombus is present. Arterial inflow will typically be high resistance flow
in the occluded AVF or graft.

39. Thrombosed Hemodialysis Graft. (A) No flow seen on
spectral Doppler (no flow on color Doppler; not shown).
(B) Color and spectral Doppler of artery upstream (cranial)
from graft takeoff shows high-resistance waveform
expected in graft thrombosis.