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84
Indications/Contraindications
When is an
aneurysm
repair
indicated?
Diameter > 5.5cm (male) or > 5.0 (female),
recent rapid aneurysm expansion (> 5mm in
6months or 10mm per year), patient symptoms,
and AAA leak or rupture
Earlier repair may be indicated in the presence
of the following:
Inheritable condition; intervene at diameter
> 5.0cm (male) or > 4.5 (female).
Saccular aneurysm.
Presence of penetrating atherosclerotic ulcer.
Presence of pseudoaneurysm.
Presence of thrombotic or embolic
complications.
Signs or symptoms of infection or
inflammation.
Presence of coexisting iliac disease.
What are
the available
treatment
options for
AAA?
Open surgical repair (mortality as high as
7% and morbidity as high as 50% with open
elective repair)
Patients with cardiac, pulmonary, or renal
dysfunction can pose high operative and/or
anesthesia risk.
EVAR
Who are ideal
candidates for
EVAR?
Those with infrarenal aneurysms. Juxta-
renal aneurysm risk graft occlusion of the
renal arteries. Juxta-renal AAA is defined
as involving the infrarenal abdominal aorta
adjacent to or within 1cm of the lower margin
of the renal artery origins. Accessory renal
arteries should be identified as coverage may
lead to infarction of part of the kidney, and/or
lead to a path for future endoleak.
Access vessel large enough to accommodate
stent graft delivery system (6–8mm).
Non-tortuous vessels.
Patients in whom the IMA is not the
predominant blood supply to the colon (as may
be seen in the setting of significant narrowing of
the SMA).
D. Daye
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Relevant Anatomy
What is a unique
change of the aortic
wall as it descends
from the thorax to
the abdomen?
The number of collagen layers in the
media decreases. The size and number of
adventitial vasa vasorum also decrease.
What is the
pathophysiology
of aneurysm
formation?
Aneurysm expansion is proportional
to the degree of wall stress and
inversely proportional to wall thickness.
Degenerative thinning of the media is
seen. Aneurysmal walls demonstrate
decreased number and degraded
organization of concentric smooth muscle
cells and elastic lamina. Fragmented
collagen is also seen.
Where are most
AAAs located?
95% of AAA are located below the renal
arteries (infrarenal). Up to 40% of AAAs
are associated with iliac artery aneurysms,
which may require the placement of a
bifurcated aortic endograft.
What is the
definition of a true
aneurysm?
Localized dilation of all three layers of a
vessel
What is the most
common shape of
an atherosclerotic
aneurysm?
Fusiform
What is the most
common shape of a
mycotic aneurysm?
Mycotic aneurysms are most often
pseudoaneurysms and saccular in structure.
Blood culture is positive 50% of the time
(approximately 50% S. aureus, frequently
salmonella).
Can the size of an
aortic aneurysm be
reliably evaluated by
angiography?
No. Large aneurysms often have a mural
thrombus. With only the lumen opacified,
the outer size of the aneurysm cannot be
appropriately evaluated.
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Relevant Materials
What are the types
of stent graft that
are available?
Straight
Tapered
Bifurcated
Fenestrated
Branched
What are the
general three
components of an
endoprosthesis
device?
A delivery system for graft introduction and
deployment
A high radial force, self-expanding metallic
stent framework
Supports and allows for vascular
attachment
Graft fabric that excludes the aneurysm and
serves as a new conduit for blood flow
What is the most
commonly used
device to repair an
AAA?
Bifurcated stent graft
Which features of
the aneurysm neck
are suitable for
EVAR?
At least 15mm in length
Non-aneurysmal (18–32mm in diameter
with parallel walls)
Angled less than 45°
Relatively free of major calcification or
thrombus
What is the
recommended
diameter of a stent
graft?
10–20% greater than the diameter of the
implantation site
What is an
important
anatomic
consideration
for access
when planning
endovascular AAA
repair?
The common femoral artery, external iliac
artery, and common iliac artery diameters
should all be measured from inner wall
to inner wall on axial CT and should be
compatible with accommodating 16–22
Fr introducer sheaths for delivery of
endografts.
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General Step by Step
What are the general,
overall steps involved
with any AAA patient
scheduled to undergo
EVAR?
Imaging and planning
Graft and patient selection
The EVAR procedure
Post-procedure surveillance
Management of EVAR-related
complications
What is the usual access
used in EVAR?
Bilateral common femoral arteries
What type of catheter
is typically first
introduced?
Calibrated/marker pigtail or straight
flush catheter
Where should the first
marker on the catheter
be positioned for length
measurements?
Lowest renal artery origin
Once the stent graft
device is introduced over
a superstiff wire, where
is the superior end of the
endograft positioned?
At the level of the lowest renal artery
When placing a
bifurcated stent graft,
what is the purpose of
performing a retrograde
angiogram at the bottom
of the graft limbs?
Preserve hypogastric artery flow.
Limbs should terminate within 1cm of
the hypogastric artery.
If a suitable distal landing zone is not
present in the common iliac artery,
limbs may need to be extended into
the external iliac artery, which may
require embolization of one or both
hypogastric arteries.
What should you
look for on the final
angiogram?
Aneurysm exclusion without presence
endoleaks. Normal perfusion of
kidneys and lower extremities.
(continued)
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What is the
postoperative
management following
EVAR?
Admit overnight: Analgesia, IV
fluids, diet, monitor access, CPR
status, ambulation ability, and overall
postoperative state.
Medical management should be in line
with management of coronary artery
disease.
Complications
What is an
endoleak?
Residual blood flow in the aneurysm sac
How do you assess
for endoleaks?
CTA, MRA, or US.Contrast-enhanced
ultrasound is an emerging, cost-effective
modality, which may be used to assess for
endoleak.
What are the
five types of
endoleaks?
Type I: leak at endograft ends due to an
inadequate seal
Type II: aneurysm sac filling via a branch
vessel
Type III: leak through a defect in the graft
fabric or junctional separation of modular
components
Type IV: porous graft
Type V: endotension (the continued expansion
of the aneurysm sac without radiographic
evidence of a leak site)
What is the most
common type of
endoleak?
Type II: collateral vessels leading to residual
flow into aneurysm sac.
Treatment is considered somewhat
controversial, though some accepted
indications for treatment include growth of
the aneurysm sac by 5mm or other features
that indicate persistent pressurization of the
native sac, such as persistent endoleak on
follow-up, large feeding or draining artery, and
presence of high flow within the aneurysm sac.
The most commonly involved feeding arteries
are the IMA and lumbar arteries.
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In what case can
colonic ischemia
take place
following EVAR?
Occlusion of the IMA by the endograft in a
patient who does not have well-developed
collaterals
What is anterior
spinal syndrome?
Paraplegia, loss of pain/temperature sensation,
and loss of bladder/bowel control
If a patient
presents with
anterior spinal
syndrome after
EVAR, which
vessel did the
endograft occlude?
The artery of Adamkiewicz
If a patient
has undergone
bilateral
hypogastric artery
embolization to
prevent type 2
endoleak, which
symptoms may
be expected on
follow-up?
Erectile dysfunction
Buttock claudication
Spinal cord, bladder, and colon ischemia
This procedure may be staged prior to EVAR
in an effort to promote collateral circulation
formation and avoid ischemic complications
prior to exclusion.
What are
other possible
complications of
EVAR?
Aortoenteric fistula
Aortovenous fistula
Erectile dysfunction
Graft infection
What are some
clinical features
of aortoenteric
fistula?
More common in the open surgical
population (0.6–2.0% annual incidence)
Abdominal pain and sepsis
Classically a “herald,” self-limited bleed
followed by catastrophic bleeding
Nearly always involves the duodenum
On cross-sectional imaging, expected peri-
graft edema, fluid, and ectopic gas can persist
up to 3–4weeks. Persistence beyond this
period of time should raise suspicion for
infection. Look for loss of fat planes between
graft and bowel.
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Landmark Research
According to recent
studies, what are the
main advantages of
EVAR compared to
open repair?
Lower blood loss
Fewer days in hospital post-procedure
Lower complication rates
Decreased in-hospital and 30-day
mortality
How does the long-
terms mortality differ
between EVAR and
open surgical repair?
Lower mortality at 4years with EVAR
(4%) compared to open repair (7%),
though longer-term mortality rates
demonstrate similarity
What is the utilization
trend of EVAR that has
been recently reported
in the literature?
EVAR has been progressively replacing
open surgical repair for infrarenal AAA
repair.
Common Questions
How does endovascular
abdominal aortic
aneurysm repair
(EVAR) compare to
open surgical repair in
the early perioperative
period? After 2years?
After 8years?
EVAR demonstrates lower rates
of morbidity and mortality when
compared with open surgical repair in
the early perioperative period (within
30days post-procedure), equivalent
outcomes after 2years, but higher
total mortality and aneurysm-related
mortality after 8years.
What is Laplace’s law
and how does it relate
to aneurysms?
The law states that tension (T) equals
pressure (P) multiplied by the diameter
(D). It states that the larger the radius
of the sphere, the greater the wall
stress. As the aneurysm enlarges, the
greater the stress on the aortic wall
increases the risk of rupture.
How long is endograft
imaging surveillance
recommended after
EVAR?
Indefinitely
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At what time intervals
is imaging surveillance
performed after EVAR?
Follow-up may be obtained at 1month
and 12months. A 6-month follow-up
may be obtained if there is presence
of an endoleak, and then yearly. Key
features to be able to identify are
any evidence for graft thrombosis,
migration, or fracture.
Further Reading
Beebe HG, etal. Screening and perioperative imaging of candidates
for conventional repair of abdominal aortic aneurysms. Semin
Vasc Surg. 1999;12:300–5.
Diwan, etal. Incidence of femoral and popliteal artery aneurysms
in patients with abdominal aortic aneurysms. J Vasc Surg.
2000;31(5):863.
EVAR trial participants. Endovascular aneurysm repair vs. open
repair in patients with abdominal aortic aneurysm (EVAR trial 1):
randomized control trial. Lancet. 2005;365:2179–86.
Giles KA, etal. Decrease in total aneurysm-related deaths in the era
of endovascular aneurysm repair. J Vasc Surg. 2009;49:543–50.
Guirguis-Blake JM, et al. Ultrasonography screening for abdom-
inal aortic aneurysms: a systematic evidence review for
the U.S. Preventive Services Task Force. Ann Intern Med.
2014;160(5):321.
Hiramoto JS, et al. Long-term outcomes and reintervention after
endovascular abdominal aortic aneurysm repair using the Zenith
stent graft. J Vasc Surg. 2007;45:461–6.
Lawrence PF, etal. The epidemiology of surgically repaired aneu-
rysms in the United States. J Vasc Surg. 1999;30(4):632.
Parodi JC, etal. Transfemoral intraluminal graft implantation for
abdominal aortic aneurysms. Ann Vasc Surg. 1991;5:491–9.
Prinssen M, etal. A randomized trial comparing conventional and
endovascular repair of abdominal aortic aneurysms. N Engl J
Med. 2004;351:1607–18.
Veith FJ, etal. Nature and significance of endoleaks and endoexten-
sion: summary of opinions expressed at international conference.
J Vasc Surg. 2002;35:1029–35.
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R. Chand et al. (eds.), Essential Interventional Radiology
Review, https://doi.org/10.1007/978-3-030-84172-0_18
Evaluating Patient
What is a thoracic
aortic aneurysm
(TAA)?
Localized dilatation of the thoracic aorta
greater than 50% of normal. The upper
limit of normal caliber for the descending
thoracic aorta is 3–3.5cm.
What are the two
major types of
aneurysms?
80% are fusiform (uniform and
circumferential) and 20% are saccular
(localized outpouching).
What chest X-ray
findings that should raise
suspicion for a thoracic
aortic aneurysm?
Widening of the mediastinal silhouette,
enlargement of the aortic knob, and
tracheal or esophageal deviation
Chapter 18
Thoracic Aortic
Aneurysm Chapter
PeytonCramer andLourdesAlanis
P. Cramer (*)
Department of Radiology, New York Presbyterian Hospital Weill
Cornell Medicine, New York, NY, USA
McGovern Medical School, UT Health Science Center at Houston,
Houston, TX, USA
e-mail: pmc9010@nyp.org
L. Alanis
Interventional Radiology, Radiology Associates of San Luis
Obispo, San Luis Obispo, CA, USA
(continued)
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Which imaging
modality is most
critical for evaluating
thoracic aortic
aneurysms?
Computed tomography angiography
(CTA) from the thoracic inlet to the
femoral artery bifurcations. Non-contrast
images help visualize calcifications and
intramural hematomas, while arterial-
phase angiography provides accurate
aneurysm measurements.
What are additional
imaging modalities
that can be used
to further evaluate
thoracic aortic
aneurysms?
Magnetic resonance angiography
(MRA), transesophageal echo (TEE),
and intravascular ultrasound (IVUS)
Why is it important
to thoroughly assess
the femoral and iliac
vasculature?
Significant tortuosity, thrombus,
or calcification might preclude an
endovascular approach. Adequate vessel
caliber is essential for accommodating
the endograft delivery system.
High Yield History
What is the prevalence of
thoracic aortic aneurysms?
6–10 per 100,000
What is the average age of
diagnosis?
65years old, with women
presenting approximately
10years later than men
Is there a gender
predominance?
Slightly, with a male-to-female
ratio of 1.5:1–1:1
What are the risk factors? Atherosclerosis, aortic
dissection, connective tissue
disorders, family history, trauma,
infection, and vasculitis
P. Cramer and L. Alanis
https://t.me/med1917
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