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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3892_Библиотеки_им_академика_М_И_Перельмана
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364
What is the most
common site of
pseudoaneurysm
(PSA) formation?
The common femoral artery is the most
common site of PSA, largely secondary
to iatrogenic puncture for arterial
catheterization. Femoral PSA occurs in
0.6–6% of femoral interventions. The wide
prevalence of coronary interventions in
the United States accounts for a significant
portion of these PSAs, usually from a
“low puncture” where the artery is not
supported by surrounding structures
(e.g., femoral head) to aid in hemostasis.
Degenerative PSA formation over time
is also common in arteriovenous fistulas
created for hemodialysis.
How do
pseudoaneurysms
present?
Patients will present with symptoms of
mass effect, bleeding, a palpable mass, or
the sensation of pain or a femoral bruit.
The expanding PSA may compress the
adjacent nerve or vein, resulting in distal
extremity numbness or edema, respectively.
The overlying skin may develop ischemia,
also from underlying compression.
How are
pseudoaneurysms
evaluated and
followed?
Duplex ultrasonography has a sensitivity
and specificity of 94% and 97%,
respectively, for femoral PSA.Color
Doppler will demonstrate a swirling
pattern of flow, often referred to as the
classic “yin-yang sign.” to-and-fro flow
signal in the PSA sac indicates a patent
and non-thrombosed pseudoaneurysm with
inflow and outflow.
J. Chen and A. Ramjit
https://t.me/med1917
365
High Yield History
What are the
risk factors
for PAA?
Male gender (M:F ratio >20:1), hypertension,
family history of aneurysm, connective tissue
disorder, smoking history, or prior aneurysm. In
contrast, certain visceral artery aneurysms (e.g.,
splenic artery, renal artery) are more common in
women.
What is
the natural
history of a
PAA?
The most common complication of popliteal
artery aneurysms (the most common PAA) is
acute ischemia, either from thrombosis or distal
embolization. Intermittent claudication, pain, and
venous compression resulting in DVT are also
potential complications. Femoral artery aneurysms
(FAAs), the second most common PAA, do
not have a well-defined natural history. Perhaps
due to the relatively low incidence and often
asymptomatic nature of FAA, multiple small case
series demonstrate wide variability in the rate of
complication. In general, PAA growth and the
potential for rupture are difficult to predict. Some
PAAs do not expand over time.
Upper extremity PAAs, however, more frequently
become symptomatic than lower extremity PAAs,
with thromboembolic complications being most
common. Rupture is less likely the more distal the
aneurysm in the upper extremity.
What is
the natural
history of
visceral
artery
aneurysms
(VAAs)?
The natural history of VAAs is unknown. Most
symptomatic patients present following rupture
with significant associated morbidity; however, no
definite risk factors predisposing VAA to rupture
have been identified. Because even small VAAs
can rupture, no size criteria for repair are defined.
Although splenic artery aneurysms are least likely
to rupture, there is increased risk for rupture
during pregnancy. Hepatic artery aneurysms have a
relatively high risk of rupture.
(continued)
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What is the
association
of splenic
artery
aneurysms
and arterial
calcification?
Calcification has been traditionally thought
to represent aneurysmal stability; however,
calcification is seen in 90% of ruptured splenic
aneurysms, and thus the presence of calcifications
should not be used in risk assessment.
What are the
risk factors
for PSA
formation?
Poor puncture technique (as above), inadequate
postprocedural puncture site compression,
periprocedural anticoagulation, large-bore sheath
placement (≥7 Fr), hypertension, coagulopathy,
hemodialysis, and female gender
Indications/Contraindications
What is the
indication for
PAA repair?
All symptomatic PAAs should be repaired.
Additionally, a PAA should be repaired when
it is twice the size of the native vessel or
when increasing in size. As a rule of thumb,
most aneurysms ≥2cm require treatment.
Unfortunately, aneurysm diameter does
not predict risk of rupture as compared to
abdominal aortic aneurysm.
What patient
factors preclude
endovascular
repair of popliteal
artery aneurysm?
Patients who often maintain >90° flexion
of the knees (e.g., gardeners, carpenters)
have higher risk of stent kinking/occlusion.
Additionally, stenting should not be
performed in patients with contraindication
to antiplatelet drugs.
In what clinical
scenario is
open surgical
intervention
recommended
over endovascular
repair for PAA?
In cases of aneurysm rupture and
hemodynamic instability, or where the
patient’s anatomy is unsuitable for
endovascular repair. There is currently no
good data on endovascular management in
the emergent setting.
J. Chen and A. Ramjit
https://t.me/med1917
367
What is the
indication for
visceral artery
aneurysm (VAA)
repair?
Traditionally, intervention has been
recommended for aneurysms ≥2cm,
aneurysms with rapid growth, or any
symptomatic aneurysm. With increasing use
of endovascular repair, and with poor data on
size criteria as an indication for intervention,
earlier and more aggressive intervention is
replacing serial surveillance. Intervention
should be offered to pregnant women with
splenic artery aneurysm due to the increased
risk of rupture.
What is the
indication for
PSA treatment?
The main consideration for treatment
is whether the PSA will spontaneously
thrombose, with likelihood generally tied to
the size of the PSA.Limited studies have
been inconsistent although, in general, a PSA
<2cm can be safely observed, a PSA ≥3cm
should be treated, and those measuring
2–3cm should be more closely monitored
or treated. Otherwise, all symptomatic
PSAs should be treated. This would include
PSAs with associated soft tissue necrosis,
distal neuralgia or ischemia, pain, or rapid
expansion, regardless of size.
What are the
contraindications
to ultrasound-
guided thrombin
injection of PSA?
A short, wide PSA neck is a contraindication
to thrombin injection for risk of thrombin
distal embolization leading to thrombosis.
Additional contraindications include
overlying tissue necrosis, presence of AV
fistula, and the presence of limb ischemia.
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Relevant Anatomy
What are
the proximal
arteries of
the lower
extremity?
The external iliac artery turns into the common
femoral artery at the inguinal ligament. The
common femoral artery terminates after giving
rise to the profunda femoris, then becoming
the superficial femoral artery. The superficial
femoral artery turns into the popliteal artery at
the adductor canal.
What are the
distal arteries
of the lower
extremity?
The popliteal artery terminates as the anterior
tibial artery and the tibioperoneal trunk. The
tibioperoneal trunk then divides into the
posterior tibial and peroneal arteries.
What are
the arteries
of the upper
extremity?
The subclavian artery terminates at the first
rib, then becoming the axillary artery. The
axillary artery terminates after giving rise to the
circumflex humeral arteries, then becoming the
brachial artery. The brachial artery bifurcates just
distal to the humeral trochlea giving rise to the
radial and ulnar arteries.
What part of
the popliteal
artery is most
commonly
affected?
Middle third. The proximal third is the second
most affected, and aneurysm of the distal third
is the least common. Aneurysms of the distal
third of the popliteal artery often extend into the
tibioperoneal trunk and are much more prone
to thrombosis and subsequent embolization.
The popliteal artery may be of increased
susceptibility to aneurysm formation due to
a complex embryology, associated with three
original segments as described above.
What are the
two types
of common
femoral artery
aneurysms
(FAAs)?
Cutler and Darling in 1973 originally classified
FAAs according to their relation to the femoral
artery bifurcation. Type 1 FAAs are limited to
the common femoral artery, and type 2 FAAs
extend into the bifurcation, involving the origin
of the profunda or the superficial femoral artery.
J. Chen and A. Ramjit
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What portion
of the splenic
artery is most
commonly
affected by
VAA?
Distal third, followed by middle third
Relevant Materials
What size sheath
is used during
endovascular repair
of PAA?
Depending on the intended stent-graft
size, a 6- or 7-F sheath is usually used.
How are stent-grafts
advanced into the
PAA?
Stents are advanced over a 0.018″ or
0.035″ guidewire which has been passed
beyond the aneurysm.
What is a commonly
used stent-graft?
The Viabahn Endoprosthesis (Gore,
Flagstaff, Arizona) is a commonly used
self-expanding, covered stent-graft. It has
improved flexibility compared to older
generation devices.
Are multilayered
stents useful in PAA
repair?
No. Multilayered stents have been
associated with increased risk of stent
thrombosis, both in PAA and AAA repair.
What medications
are given during and
after stent placement
in PAA repair?
Heparin is often administered, with
antiplatelet therapy started post-repair.
Antiplatelet (clopidogrel, aspirin) therapy
has been shown to be a predictor of
endovascular repair success.
What size needle is
typically used for
ultrasound-guided
thrombin injection of
a PSA?
A 22-gauge needle is usually sufficient;
however, a 21-gauge needle may be
necessary for deeper lesions.
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General Step by Step
What is the
gold standard
of treatment
for PAA
management?
Open repair including aneurysm resection and
placement of an interposition or bypass graft,
usually with a great saphenous vein graft. Repair
with a prosthetic (Dacron or PTFE) graft is
also possible. While aneurysm excision without
vascular reconstruction is possible, many of
these patients will subsequently have arterial
insufficiency symptoms.
What are the
advantages of
endovascular
management
techniques
for PAA?
Endovascular techniques are increasingly
popular, particularly for patients with multiple
comorbidities who might not tolerate anesthesia
and surgery. Open surgical repair can be
associated with significant morbidity from major
surgical dissection. Endovascular techniques often
afford decreased blood loss, shorter procedure
time, and decreased length of stay compared
to open procedures. Nonetheless, cost savings
afforded by endovascular management (e.g.,
decreased operative time and length of stay) may
be offset by the increased cost of devices needed
for endovascular repair.
Why are
femoral
artery
aneurysms
less
favorable for
endovascular
repair?
The close proximity to the inguinal ligament
results in focal compression/bending, increasing
the risk of focal neointimal hyperplasia and
possible stent fracture. Additionally, the proximity
to the femoral bifurcation/profunda makes the
possibility of fracture particularly dangerous.
J. Chen and A. Ramjit
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In a patient
with multiple
aneurysms,
which are
treated first?
In general, any abdominal aortic aneurysm is
treated first, except in the case of acute limb
ischemia. Concomitant ipsilateral PAAs in tandem
can usually be repaired in the same operative
setting (e.g., femoral and popliteal aneurysm).
In contrast, a staged management algorithm is
usually used for contralateral PAAs.
What is the
endovascular
treatment of
PAA?
Many of the anatomical considerations of
endovascular therapy are similar to the treatment
of abdominal aortic aneurysm. Stent placement
requires a 1.5–2.0-cm proximal and distal landing
zone, according to manufacturer specification,
to minimize stent migration and endoleak.
Given that the distal vessel is often of smaller
diameter than the proximal aspect, multiple
devices of unequal diameters are often necessary.
The distal/smaller stent is placed first, and the
larger stents are placed inside the prior, building
proximally. Stent-graft size is often chosen with a
small amount (1mm) of oversizing. Completion
angiography, often with a crossed joint in flexion,
is necessary to confirm aneurysm occlusion and to
ensure stent flexibility.
(continued)
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How are
PSAs
treated?
The mainstays of treatment include ultrasound-
guided direct compression of the PSA, ultrasound-
guided thrombin injection, and open surgical
repair. Less common endovascular approaches
include utilization of coils, glue, and occlusive
stents:
Ultrasound-guided compression: Pressure is
usually held for up to two cycles of 10–20minutes,
assessing for persistent flow within the PSA after
each cycle. The patient should then keep the
affected leg flat for 6hours, and the PSA should
be reassessed for flow 24–48hours later. Success
rates of 66–86% are reported, depending on PSA
size, anticoagulation status, and body habitus.
Ultrasound-guided thrombin injection: The PSA
is punctured under direct visualization with US
guidance. 0.1–0.2-mL aliquots of 1000U/mL of
thrombin are injected until flow in the PSA stops.
The patient should be placed on bed rest for
1hour with neurovascular checks performed, and
the PSA should be reassessed for flow in 24hours.
Success rates of 93–100% are reported.
Surgical repair: In general, surgical treatment
is indicated when (1) urgent control of the
PSA is needed (e.g., rupture, rapid expansion,
compressive neuropathy, or limb ischemia), (2)
if a soft tissue defect is present (e.g., suture line
dehiscence, wound infection, soft tissue ischemia),
or (3) if a secondary pathology requires surgical
intervention (e.g., presence of arteriovenous
fistula or if the patient is undergoing anesthesia
for separate procedure). To repair the PSA, a
direct cut down is made to achieve proximal
and distal control of the arterial lesion. The PSA
is then opened and the arteriotomy is directly
repaired with sutures, or, if there is significant
injury to the artery, a saphenous vein graft
may be used for an interposition graft or patch
angioplasty.
J. Chen and A. Ramjit
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Complications
Why is upper
extremity PAA
more dangerous
than lower extremity
PAA?
PAA in the upper extremity should be
repaired, even when asymptomatic, as
there is a greater risk of thromboembolism.
What is the
complication rate
of PAAs treated
conservatively?
42–75% of asymptomatic patients with
PAA that are treated conservatively will
develop complications in 5years, with
risks varying based on aneurysm location.
14% of popliteal artery aneurysms become
symptomatic per year.
What complications
arise from
endovascular repair
of PAA?
Puncture site hematoma, stent occlusion,
stent migration or fracture, and endoleak
What is the
most common
complication of
ultrasound-guided
thrombin injection
of PSA?
Distal embolization is reported in
up to 2% of patients. In the event of
embolization (either in the femoral artery
or distally), the patient should be placed on
therapeutic heparin, with a low threshold
for catheter-directed thrombolysis with
tissue plasminogen activator (tPA).
How are infected
PSAs treated?
Conservative treatments (discussed
above) are not appropriate for infected
PSAs. Appropriate antibiotic therapy,
debridement of infected tissue, and arterial
repair (often with interposition graft) are
critical.
Landmark Research
Lovegrove RE, Javid M, Magee TR, etal. Endovascular and
open approaches to non-thrombosed popliteal aneurysm
repair: a meta-analysis. Eur J Vasc Endovasc Surg.
2008;36:96–100.
30 Peripheral andVisceral Artery Aneurysm
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