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Angioplasty/Stenting/Lysis/Thrombectomy of Hemodialysis Access 253
Fig. 3 Left subclavian
pacemaker with central
venous stenosis/occlusion
Fig. 4 (a)Leftwristfistula
with focal juxta-anastomotic
cephalic vein stenosis. (b)
Left forearm graft with
venous anastomotic stenosis
Indications
• Angioplasty of dialysis grafts and fistulae is indicated when there is greater
than 50% diameter stenosis and an abnormal clinical/physiologic indicator of
dysfunction:
254 H. Shah and G. McLennan
b
Low flows – less than 600 mL/min or less than 1,000 mL/min with greater
than 25% decrease in flow over 3–4 month period
b
Elevated dynamic or static venous pressures
b
Elevated urea recirculation (more useful in fistulae than grafts)
b
Arm swelling – central venous stenosis
b
Abnormal physical exam – poor thrill, pulsatile
b
Poor maturation of fistula
b
“Pulling Clots” – arterial inflow stenosis
• Extremity edema caused by central venous stenosis should be treated by
angioplasty. Stent placement is recommended for elastic recoil (>50%) after
angioplasty or for restenosis within 3 months following angioplasty.
• Stent placement in the peripheral veins is indicated for failed angioplasty (>2
angioplasties needed within 3 months) in a surgically inaccessible lesion or other
surgical contraindication as well as for angioplasty-induced rupture.
• It is critical to determine whether the stented segment will impact the viability of
a functional fistula in the future prior to placing a stent in the periphery. It may be
better to surgically revise an access than stent it if the surgeon can create a viable
fistula.
• Thrombectomy is indicated for occluded grafts and fistulae and should be
performed as early as possible.
Contraindications
• Prophylactic angioplasty of a stenosis in the absence of a clinical indicator of
access failure (low flows, high venous pressures, elevated recirculation, etc.) is
discouraged.
• Uncorrectable severe coagulopathy is a relative contraindication.
• Thrombosed grafts and fistulae which are suspected of being infected should not
undergo percutaneous thrombectomy due to the risk of sepsis and septic emboli.
b
Be aware that a reactive phlebitis can occur in the region of the clotted outflow
vein and less commonly over the clotted graft resulting in local erythema and
tenderness that can mimic an infection.
• Severe allergy to iodinated contrast agents is a relative contraindication. Options
include pre-medication or use of alternate contrast agents (carbon dioxide gas,
gadolinium-based agents).
b
Limit the use of gadolinium-based agents in an effort to reduce the risk of
nephrogenic systemic fibrosis.
• Percutaneous intervention on a newly placed (less than 2–4 week old) graft is a
relative contraindication.
Angioplasty/Stenting/Lysis/Thrombectomy of Hemodialysis Access 255
Patient Preparation
• PatientNPOforatleast6h–formoderate sedation
• Labs – coagulation studies (INR, PTT), platelet count, electrolytes
• If potassium elevated consider management options:
b
Check EKG for spiked T waves
b
Give calcium gluconate
b
Consider temporary catheter and urgent dialysis and then treat the patient the
following day
Anatomy: Grafts and Fistulae
• Upper extremity fistulae are the preferred access for hemodialysis patients. These
include wrist (radiocephalic), elbow (brachiocephalic), or transposed brachial
basilic arteriovenous fistulae (Fig. 5).
Fig. 5 (a) Right wrist
radiocephalic fistula. Note the
metallic coils from prior
embolization of a
“competing” side branch of
the cephalic outflow vein. (b)
Left elbow brachiocephalic
fistula
256 H. Shah and G. McLennan
• Each extremity can support nine different fistula configurations
b
Radiocephalic
b
Brachiocephalic
b
Transposed brachiobasilic
b
Transposed radioulnar
b
Graz variation
b
Transposed brachiobrachial
b
Transposed radiointerosseous
b
Transposed femoral vein to brachial artery
b
Transposed femoral vein to radial artery
• Understanding the surgery that was performed is critical to understanding the
potential access sites and interventions needed
• Forearm or upper arm grafts are acceptable for access if a fistula cannot be placed
(Fig. 6)
• Lower extremity fistulae or grafts are acceptable if upper arm sites are exhausted
(Fig. 7)
• Tunneled catheters are the least preferred type of chronic access for hemodialysis
patients.
Fig. 6 (a) Right forearm loop
graft. (b) Left upper arm
bovine graft
Angioplasty/Stenting/Lysis/Thrombectomy of Hemodialysis Access 257
Fig. 7 (a) Lower extremity loop graft. (b) Closeup of the arterial and venous anastamoses to the
femoral artery and vein
Equipment
• Needles
b
18 or 19G single or double-wall that accept 0.035" guidewires
b
21G needle in micropuncture set
b
Sheathed needles such as the Amplatz needle
•Wires
b
0.018" wire in micropuncture set
b
0.035" guidewires for most angioplasty and stent interventions
b
Hydrophilic, non-hydrophilic
b
Steerable, non-steerable
b
0.014" wires for “coronary” type angioplasty balloons
b
0.018" wires for other low-profile angioplasty balloons
• Catheters
b
Micropuncture catheter with 3F inner cannulas and 4 or 5F outer catheter
b
4 or 5F diagnostic catheters
• Sheaths
b
Most commonly used are 5–7Fr sizes. Depends on type of intervention
planned.
258 H. Shah and G. McLennan
b
4F can be used for arterial interventions with coronary or other low-profile
angioplasty balloons.
b
5–6F can be used for most peripheral angioplasties, mechanical thrombec-
tomy, and peripheral stents
b
High-flow sheaths often useful in mechanical thrombectomy cases.
b
7F usually needed for central angioplasties and stents
• Angioplasty balloons
b
Generally, high-pressure non-compliant balloons are used.
b
5–8 mm diameter sizes are commonly used for peripheral venous stenoses
b
10–12 mm and larger diameter sizes usually needed for central venous
stenoses.
b
3–6 mm diameter sizes often required for arterial inflow stenoses with smaller
sizes for wrist fistulae and larger for elbow fistulae and upper and lower
extremity grafts.
b
Semicompliant “coronary” type balloons are often useful in wrist fistulae with
radial artery inflow stenosis as they allow a range of balloon diameter size
depending on the inflation pressure applied.
b
Cutting balloons not routinely used but have a niche role in resistant stenoses
or when high-pressure angioplasty may not be desired due to potential baro-
trauma or rupture risk such as at the arteriovenous anastomosis of fistulae. The
microsurgical blades of the cutting balloon allow for complete balloon waist
effacement at low pressures.
• Pressure inflators – commonly used especially for high-pressure inflation or when
using coronary type balloons.
• Stents
b
Self-expanding stents most commonly used due to their flexibility.
b
Balloon-expandable stents are contraindicated in areas which are potentially
compressible such as the peripheral veins and across joints.
b
Bare stents typically used but covered stents may be needed for large ruptures.
b
No current evidence to support use of drug-eluting stents
b
Some evidence suggests lower restensosis rate of covered stents ver-
sus angioplasty in venous stenosis associated with dialysis grafts (Impra
Trial)
• Guiding catheters in 5–8F sizes may be useful for thromboaspiration
• Embolectomy catheters (Fogarty-type)
b
4–6F
b
Over-the-wire and not-over-the-wire available
b
Most commonly used for thrombectomy cases and disrupting the arterial plug
at the anastomosis
Angioplasty/Stenting/Lysis/Thrombectomy of Hemodialysis Access 259
• Adherent clot catheters
b
Useful for removing resistant adherent clot/pseudointimal hyperplasia in
grafts.
b
Do not use in native vessels
• Pulse spray catheters – 4 or 5F commonly used with a variety of infusion side
hole lengths (5–50 cm)
• Mechanical thrombectomy devices
b
Wide variety available
b
Over-the-wire and not over the wire devices
b
Wall contact versus non-wall contact devices
b
Limited run-time for some devices due to hemolysis
b
Adenosine release from mechanical disruption may lead to bradycar-
dia/dysrythmias
Pre-procedure Medications
• Sedation and analgesia
b
A local anesthetic (e.g., Lidocaine) is used for the access puncture site
b
Moderate sedation and analgesia with agents such as Fentanyl (Sublimaze)
and Versed (Midazolam) enhances patient comfort
• Antibiotics
b
Recommended that an antibiotic be used for thrombectomy cases to cover skin
organisms ( e.g., Cefazolin).
b
Optional use for other interventions.
• Antispasmodic agents
b
Venospasm at the venous puncture site may be severe, especially in outflow
veins of immature fistulas. An antispasmodic skin cream (e.g., Nitropaste,
papaverine cream) applied to the anticipated puncture site prior to the pro-
cedure may be helpful for prophlaxis against spasm but is not routinely or
widely used.
Procedure
Physical Exam
• A normal access will have a nice thrill throughout the venous outflow.
• Pulsatility, except near the arterial anastomosis of a graft, signifies an outflow
stenosis.
260 H. Shah and G. McLennan
• There should be no abrupt transition in the thrill along the graft or outflow vein.
• In the case of a single outflow stenosis, the access will be pulsatile from the
arterial anastomosis to the site of stenosis and then have a weak thrill and poor
turgor of the outflow vein beyond the stenosis.
• A cord may be palpable at the site of the stenotic lesion.
• An arterial inflow stenosis will demonstrate a weak thrill or pulse with collapsed
(“flat”) graft or outflow vein.
• A thrombosed access will have no thrill or pulse beyond the arterial anastomosis.
• A central venous stenosis will manifest as extremity swelling/edema with
possible visible chest wall collaterals.
• Evaluate the peripheral pulses, especially if performing a thrombectomy because
of the risk of arterial emboli from the procedure.
• Also, evaluate the hand for ischemia as treatment of a venous outflow stenosis
will aggravate steal syndrome if present (Fig. 8).
• Limited ultrasound exam in the interventional suite can be a useful adjunct to the
physical exam and is especially helpful when evaluating non-mature or dysfunc-
tional fistulae. It can evaluate the site(s) of stenosis, identify non-palpable outflow
vein(s), and evaluate the extent of thrombosis.
Fig. 8 (a) Right
brachicephalic elbow fistula
with diminished flow to the
distal forearm arteries. (b)
Marked improvement in flow
to the radial and ulnar arteries
with compression of the
outflow cephalic vein in this
patient with steal syndrome
Angioplasty/Stenting/Lysis/Thrombectomy of Hemodialysis Access 261
Arterial/Venous Access
• Access the graft or fistulae based on the clinical scenario, physical exam findings,
and findings on prior exams.
• More than one access may be required, especially for treating thrombosed grafts
and fistulae and also if there are multiple stenoses located in different areas (e.g.,
central stenosis with additional stenosis near the arterial anastomosis) that cannot
be treated with a single access site.
• In patients with loop grafts, a perpendicular access into the graft apex can allow
access into both the arterial and venous limbs without requiring an additional
puncture site.
• For wrist (radiocephalic) fistulae, a single retrograde access near the
elbow/antecubital fossa allows access to most non-central lesions.
• For wrist and elbow fistula, a single antegrade access just central to the arte-
riovenous anastomosis allows access to most lesions except for arterial inflow,
anastomotic or immediate juxta-anastomotic lesions. Hemostasis following the
procedure may be more difficult, however, given the higher pressures near the
anastomosis as opposed to further central in the venous outflow.
• Brachial artery access may be required for evaluation of non-maturing dialy-
sis fistulae when the outflow vein is non-palpable, non-visible, or diminutive
in size.
• The inner catheter of a micro-puncture set is suitable for this purpose and its small
size (3F) minimizes complications such as access s ite thrombosis, hematoma, or
pseudoaneurysm (Fig. 9).
• Ultrasound is often useful especially when treating dialysis fistulae. It can help
decide where to access, and allow access into non-palpable, non-visible outflow
veins.
• A number of access needles can be used for initial access into the graft or fistula
including angiocatheters, 18/19G thin-wall needles, micropuncture type set, and
sheathed needles.
• A vascular sheath is typically required for performing angioplasty, stent place-
ment, or mechanical thrombectomy.
Fig. 9 Immature left
antecubital fistula with
fistulogram performed by
retrograde brachial artery
access using the 3F inner
cannula of a micropuncture
set
262 H. Shah and G. McLennan
Fistulography
• The entire access needs to be evaluated including the inflow artery, anastomosis,
graft (if present), outflow vein(s), and central veins.
• If there is a contraindication to iodinated contrast then consider using carbon
dioxide gas and/or gadolinium contrast agents. Try to avoid refluxing the arte-
rial anastomosis with carbon dioxide gas because of the risk of stroke but carbon
dioxide can be injected directly into the artery above the anastomosis via retro-
grade catheter or microcatheter in the brachial artery. This avoids reflux. Also
carbon dioxide tends to overestimate the degree of stenosis, as it tends to “float”
in the blood as opposed to admixing with the blood. Minimize the volume of
gadolinium agents used in order to reduce the risk of nephrogenic systemic
fibrosis.
• The arterial anastomosis of grafts can be imaged using several techniques:
b
Extrinsic compression of the outflow vein or graft central to the puncture site
b
Balloon occlusion (i.e., Fogarty, angioplasty balloon) of the outflow vein/graft
b
Retrograde puncture into the graft with advancement of a diagnostic catheter
(typically 4 or 5F) across the arterial anastomosis into the inflow artery.
• Visualization of the arteriovenous anastomosis of fistulae can be difficult. In
addition to the techniques described above for grafts, the following can be
performed:
b
For wrist fistulae, inflation of a blood pressure cuff in the upper arm to
suprasystolic pressure will aid in refluxing the anastomosis.
b
3F catheter (inner cannula of micropuncture set) access into the inflow artery.
• Perform multiple views, especially at the site(s) of suspected stenosis, when the
angiographic findings are discordant with the clinical or physical exam findings
(Fig. 10).
• Perform the fistulogram with the arm in different positions (abduction, adduction,
internal/external rotation) if there is a narrowing of the axillary or subclavian
veins or cephalic vein in the region of the humeral head to ensure that it does not
represent positional extrinsic compression.
• Identify all the sites of significant stenosis. Determine if a new or additional site
of access will be required to treat all lesions.
• For thrombosed accesses, typically a “pull-back” venogram is performed prior to
declotting the graft/fistula to identify outflow stenoses and delineate the extent of
thrombus. This is t hen followed by a complete fistulogram once flow is restored.
Intra-procedural Medications
• Sedation and analgesia as needed for patient comfort.
• Heparin