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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3955_Библиотеки_им_академика_М_И_Перельмана.pdf
Angioplasty/Stenting/Lysis/Thrombectomy of Hemodialysis Access 263
Fig. 10 (a) Right wrist radiocephalic fistula with poor thrill at the anastomosis and poor disten-
tion of the outflow cephalic vein reveals no obvious significant stenosis. (b) Repeat imaging with
craniocaudal angulation reveals severe juxta-anastomotic inflow radial artery stenosis
b
Recommended when treating clotted grafts and fistulae but is optional for
angioplasty and stent procedures.
b
Typical doses are 3,000–5,000 units IV.
b
Consider its use when treating complex lesions or when prolonged angioplasty
balloon inflation time is anticipated or needed.
b
No data to support or refute its routine use.
b
May result in difficulties with hemostasis once the sheath is removed.
If given, consider checking an activated clotting time (ACT) prior to
pulling the sheath. If ACT is greater than 200 sec, then consider delaying
sheath removal or using an adjunctive method of hemostasis (see Section
“Immediate Post-procedure Care”) in addition to or in place of manual
compression.
• Nitroglycerin
b
Use as needed to treat arterial or venous spasm.
b
Typical dose is 100 µg intravenous/intra-arterial infused at the site of spasm.
Repeat dosing as needed, but monitor for hypotension.
264 H. Shah and G. McLennan
b
Especially useful when treating poorly maturing fistulae which are prone to
spasm.
• Thrombolytics (tPA, Urokinase, etc.)
b
Can be used alone or in conjunction with mechanical thrombectomy devices.
b
Typical doses of tPA vary between 2 and 20 mg.
b
1 mg tPA is approximately equivalent to 100,000 units of Urokinase.
• Antibiotic
b
Give when treating thrombosed accesses due to concern over subclinical
infection in the clot.
b
Typically use second-generation cephalosporin to cover typical gram positive
bacteria and other typical skin flora.
b
May use Quinolones as a second line for patients with penicillin allergy.
b
No evidence to support routine use of antibiotics.
Assessing the Lesion
• Morphology/Complexity
b
Rarely calcified although this is sometimes seen in intragraft lesions.
b
May exhibit recoil and respond only to high-pressure balloon angioplasty.
b
Severe venous stenoses may look long and diffuse or even like a complete
occlusion but this is often an artifact of imaging with very poor contrast
opacification downstream from a severe, but focal stenosis.
• Location
b
Most all venous (85%)
b
10–15% arterial
• Pressure measurements are typically not needed for assessment of stenosis.
• Choosing a balloon or stent
b
Oversized balloons are commonly used with typical oversizing of 10–15%
for arterial stenoses and 20–30% (or at least 1-mm oversizing) or greater
for venous stenoses (Fig. 11). Progressive oversizing of balloons during sub-
sequent interventions of recurrent stenosis of the same lesion may result in
increased patency.
b
When treating arterial inflow lesions, especially of small caliber arteries such
as the radial artery in wrist fistulas, small profile (coronary type) balloons
advanced over 0.014" guidewires may be useful (Fig. 12).
b
Typically, self-expanding stents are used because of their flexibility.
Balloon-expandable stents, if used, should not be placed at potentially
compressible sites such as the peripheral veins or across joints but are
acceptable in central locations deep in the thorax.
Angioplasty/Stenting/Lysis/Thrombectomy of Hemodialysis Access 265
Fig. 11 (a) 6mm forearm
loop graft with long segment
stenosis extending from the
venous anastamosis into the
basilic outflow vein. (b)8
mm diameter x 10 cm length
angioplasty balloon chosen.
(c) No significant residual
stenosis following
angioplasty
Performing the Procedure
• Crossing the lesion
b
Is usually straightforward.
b
For difficult lesions or occlusions, angled catheters (e.g., Berenstein) and/or
steerable hydrophilic guidewires ( Glidewire, Roadrunner, etc.) are useful
(Fig. 13).
266 H. Shah and G. McLennan
Fig. 12 (a)Leftwrist
radiocephalic fistula with
juxta-anastomotic radial
artery inflow and cephalic
vein outflow stenoses. (b)
Angioplasty via cephalic vein
access using a 3.75 mm
“coronary” balloon. (c)Post
angioplasty of radial artery
and cephalic vein stenoses
b
If there is difficulty passing wires, catheters, or devices beyond areas of severe
tortuosity or pseudoaneurysm then extrinsic compression or manipulation may
be a useful adjunct.
• Deploying the balloon/stent
b
High-pressure non-compliant angioplasty balloons advanced over 0.035"
guidewires are commonly used. It is not unusual for venous stenotic lesions to
require in excess of 20 atm pressure in order to completely efface the balloon
waist (Fig. 14). Pressure inflators are often needed.
b
Most angioplasty balloons can be inflated beyond the rated burst pressure,
often up to 25–50% over the rated burst pressure.
Angioplasty/Stenting/Lysis/Thrombectomy of Hemodialysis Access 267
a
b
Fig. 13 (a) Tortuous
antecubital outflow vein with
focal stenosis which may
represent a hypertrophied
valve. (b) Lesion crossed and
treated using hydrophilic
catheter and guidewire and
low profile angioplasty
balloon
b
Typical balloon inflation times range from 1 to 3 min. Prolonged balloon
inflation times of greater than 3–5 min may be useful for central or elastic
stenoses.
b
Cutting balloons may be used if the high-pressure balloon waist can not be
effaced (resistant stenosis) or if there is concern about “barotrauma” when
using a very high-pressure angioplasty balloon.
b
Stents should not be placed for resistant stenoses (Fig. 15).
Stents may be placed for elastic stenoses, ruptures, and failed periph-
eral angioplasty when there is no good surgical option and for failed
angioplasty in central venous stenoses.
• Treatment of clotted graft or fistulae
b
Mechanical Methods (Figs. 16 and 17):
Access the graft or fistula directed toward the venous outflow.
Pull-back venogram is performed to demonstrate the most central extent of
thrombus and to evaluate the central veins for stenosis.
268 H. Shah and G. McLennan
a
d
b
c
Fig. 14 (a) Left upper arm graft with venous anastomotic stenosis. (b) Persistent balloon waist at
15 atmospheres pressure. (c) Complete balloon waist effacement at 30 atmospheres pressure. (d)
Post angioplasty fistulogram shows no residual stenosis
Administer adjunctive drugs: Heparin and antibiotics.
Use the device to clear the venous end of the clot. Aspirate the access after
using the device.
Puncture the access directed toward the arterial inflow.
Use the device to clear to the mid portion of the arterial end of the access
without crossing the anastomosis. The goal is to remove as much clot as
possible prior to re-establishing flow.
Use the thrombectomy device or fogarty-type balloon catheter across the
anastamosis to pull the arterial plug and re-establish flow.
Examine the access and assess for pulsatility and patency.
If the access feels like it is patent and there is forward flow, then slowly
inject a small amount of contrast to determine if there is forward flow. If
not, then continue to use the device to clear the clot until antegrade flow is
established.
Once flow is established, then perform a complete fistulogram.
Identify the underlying stenoses and treat with angioplasty and other
measures as appropriate.
b
Lyse and Wait Technique:
In the holding room, access the thrombosed access with an angiocather.
Compress the anastomosis to prevent peripheral arterial emboli and inject
2–4 mg of tPA with 3,000–5,000 units heparin into the access.
Wait for 30–90 min prior to placing patient in the angiography suite.
Angioplasty/Stenting/Lysis/Thrombectomy of Hemodialysis Access 269
a
b
Fig. 15 (a) Severe rupture of
basilic outflow vein following
balloon angioplasty. (b)
Treated by placing a long
self-expanding uncovered
stent
When patient is in the suite, access the graft and assess whether there
has been partial or complete thrombolysis. Treat any residual clot with a
fogarty balloon catheter.
Once clot is removed and flow is re-established, perform a complete
fistulogram and treat underlying stenoses as appropriate.
Endpoint
• The typical endpoint is restoration of a normal thrill to the graft or fistula.
• A successful angioplasty will have complete effacement of the balloon waist and
result in 0–30% residual narrowing. In addition, the previously abnormal clinical
indicator should return to normal.
270 H. Shah and G. McLennan
Fig. 16 (a) Clotted upper arm
graft with clot extending into
the outflow graft. (b)
Fistulogram following
successful mechanical
thrombectomy and
angioplasty of severe venous
anastomotic stenosis
• If the angiographic result is equivocal, pressure measurements can be obtained.
Pull-back pressures as well as static venous pressure measurement can be
performed.
b
For grafts, the pressure in the venous limb should be less t han 30% of systolic
systemic arterial pressure to signify that there is no significant residual venous
outflow stenosis remaining.
b
Also, flow measurement devices are available for use in the interventional
suite and may be used to document increases in access flow pre- and post-
intervention.
Immediate Post-procedure Care
• The access sheaths are removed and hemostasis is obtained by manual compres-
sion.
• Typically 5–10 min of light compression is required for hemostasis. If the outflow
stenosis could not be adequately treated with significant residual stenosis or if
heparin was given during the procedure and the activated clotting time (ACT) is
Angioplasty/Stenting/Lysis/Thrombectomy of Hemodialysis Access 271
a
b
c
Fig. 17 (a) Clotted left wrist radiocephalic fistula with sheath directed towards venous outflow
and clot in forearm cephalic vein. (b) Mechanical thrombectomy device (Angiojet). (c) Successful
mechanical thrombectomy
above 200 sec, then hemostasis may take longer due to elevated pressures in the
graft or fistula or residual anticoagulation effect.
• Other options for hemostasis include use of gelfoam, hemostatic pad, purse-string
suture, or compression device.
Follow-Up and Post-procedure Medications
• No specific follow-up is required. If a purse-string suture was used for hemosta-
sis, then this should be removed either prior to discharge from the department
or at a follow-up visit the next day or the dialysis center should be instructed to
remove the suture.
• The treated dialysis graft or fistula may typically be used for dialysis immediately
following the procedure, except for immature fistulae which will likely require a
few additional weeks to mature prior to use. The dialysis center should continue
their dialysis access surveillance program and ensure that the previously abnor-
mal clinical parameter (low flows, high venous pressures, elevated recirculation,
etc.) has returned to normal following the intervention.
272 H. Shah and G. McLennan
• No specific medications are required.
• Plavix may be considered following small vessel (e.g., arterial inflow) angio-
plasty.
Results – Per K/DOQI Guidelines
• Angioplasty is expected to have at least a 50% primary patency rate at 6 months.
• Thrombectomy is expected to have a 40% primary patency rate at 3 months.
• An immediate patency rate of at least 85% is expected for graft thrombectomy.
• Clinical outcome goals are to have a fistula thrombosis rate of less than 0.25
episodes per patient-year and graft thrombosis rate of less than 0.5 episodes per
patient year at risk. This can be accomplished by access screening combined with
prophylactic angioplasty.
Alternative Therapies – Surgical Intervention
• Surgical therapy for dialysis access dysfunction should be thought of as comple-
mentary and not competitive to percutaneous intervention.
• Due to the expense, invasiveness and potential depletion of veins as compared to
percutaneous intervention, surgery is held to a higher standard with an expected
50% primary patency at 1 year (compared to 50% at 6 months for angioplasty).
• Surgical revision is indicated for angioplasty failures (two failures within 3
months).
• Surgical revision is also suggested for percutaneous thrombectomy failures (two
failures within 1–2 months).
• Surgical therapy is the treatment of choice for suspected infected grafts.
Complications and Treatment
• Complications include vessel dissection, rupture, arterial emboli, and thrombosis.
• Dissections do not typically require treatment if they are not flow limiting.
b
Flow-limiting dissections can be managed by prolonged balloon inflation. If
unsuccessful a stent can be placed.
• Venous rupture is expected to occur in about 5% of cases, especially if the
balloons are being appropriately oversized.
b
Treatment can include prolonged balloon inflation +/– manual compression
over the rupture site to “seal” the rupture.
b
Bare stents and/or covered stents can be used if prolonged balloon inflation is
unsuccessful.