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380 D.O. Kessel
Embolic Agents
• Pre-EVAR: AVP, coils to proximal IIA.
• Selective IIAA: AVP, coils to occlude distal circulation; AVP, coils, or CIA-EIA
stent graft to occlude inflow.
Medication
• Antiperistaltic: Hyoscine (Buscopan) will improve angiography.
• Infection control: Pre-procedural broad-spectrum antibiotics.
Angiography
Access
• Plan according to the pre-procedure imaging.
• >90% from the femoral artery.
• Contralateral approach may give a more stable catheter position and may be
useful in tortuous vessels.
• Brachial artery may be used in difficult cases, but ensure that you have sufficiently
long catheters (>100 cm) and exchange length guidewires.
Angiography
• AP and iliac oblique projections may be necessary.
• Craniocaudal tilt is sometimes required in IIAA to clarify distal anatomy.
Assessing the Iliac Artery
Key features are as follows:
• Patency of contralateral internal iliac artery in terms of risk of developing
ischemic sequalae.
• Diameter and length for choosing appropriate coils/plugs.
• Extent of any aneurysm.
Angiographic Appearance
• The iliac arteries are frequently tortuous in the presence of abdominal aortic
aneurysms.
Clinical Scenarios
Pre-EVAR Embolization
• The goal is prevention of type II endoleak.
38 Internal Iliac Artery—Isolated Aneurysm and Pre-EVAR Embolization 381
• Permanent occlusion of the internal iliac artery proximal to its bifurcation.
• Ensure that there is complete occlusion before proceeding to EVAR, as any leak
will be much more difficult to treat subsequently.
• Coils may be packed against an AVP to complete embolization.
• If both IIA are to be occluded, consider interval therapy to allow collateral
development.
Embolization in Patients with IIAA
• The goal is to treat the IIAA by exclusion from the circulation.
• Either proximal or distal isolation needed to prevent retrograde filling of
aneurysms via pelvic arterial collaterals (Fig. 38.2) or distal embolization and
stent graft from CIA to EIA to occlude the inflow.
a
Fig. 38.2 Same patient as in Fig. 38.1.(a) The IIAA (black arrowheads) extends down to the bifur-
cation of the IIA. (b) Coils placed into the anterior and posterior divisions of the IIA and packing
of the aneurysm. (c) Completion angiogram showing exclusion of the IIAA. The iliac vein was
subsequently stented, the patient has been asymptomatic and 5 years regular duplex surveillance
has shown the aneurysm to be thrombosed and the iliac vein to be patent
b
c
Aftercare
Arterial Puncture Site
• Routine care.
• Try to avoid closure device if the patient is about to undergo EVAR, as
inflammatory change can complicate surgery.
Post-embolization
• Check for ischemic complications.
382 D.O. Kessel
• Buttock claudication typically improves over several weeks, even with bilateral
embolization.
Follow-Up
• CT or ultrasound to confirm exclusion of aneurysm or absence of type II
endoleak.
Keypoints
Review the pre-procedural imaging to plan the procedure.
Ensure you understand the rationale for treating each patient, as this will
ensure.
• Use coils or AVP ± stent graft.
• Correct endpoints.
• Document that the patient recognizes the risks of pelvic ischemia.
Safety
Never start embolization until you have personally reviewed the imaging.
Stick to the indications for the procedure, use appropriate agents, and
remember that the endpoints depend on the indication.
Stop if uncertain, especially if there is risk of non-target embolization!
Suggested Reading
Parry DJ, Kessel D, Scott DJA. Simplifying the internal iliac artery aneurysm. Ann R Coll Surg
Engl 2001; 83: 302–308
Chapter 39
Embolization of Visceral Arterial Aneurysms
A.N. Keeling
Clinical Features
• This chapter covers aneurysms of the abdominal visceral arteries excluding renal
artery aneurysms which are covered in Chapter 40.
• Visceral arterial aneurysms (VAA) may be true aneurysms or pseudoaneurysms;
they are defined as a localized dilatation >1.5 times the expected arterial diameter.
A prevalence of 0.1−2% up to 10% with reported in autopsy series.
• Etiology is variable and depends on the site. Most patients with VAA are in their
sixties. Pregnancy is a recognized risk factor for rupture.
• Recent increase in diagnosis of visceral aneurysms is most likely due to the inci-
dental finding of asymptomatic VAA with contemporary imaging and imaging
reformats (Fig. 39.2a, 39.2c).
• One-third VAA are associated with non-visceral aneurysms, one-third are
multiple.
Natural History
• Little is known about the natural history; some have been observed to r emain
stable or be slow growing on serial imaging.
Clinical Presentation
Many asymptomatic VAA are diagnosed incidentally on imaging; symptomatic
aneurysms present with rupture or distal complications.
Rupture
• Rupture risk is up to 22% and rupture has a high reported mortality said to be as
high as 90% for celiac axis, 50% for hepatic artery, and 36% for splenic artery.
Mortality is likely to be highest in patients with significant co-morbidity, e.g.,
pancreatitis (Chapter 29) and in the post-operative period especially in patients
with sepsis.
Transcatheter Embolization and Therapy,
Techniques in Interventional Radiology, DOI 10.1007/978-1-84800-897-7_39,
C
Springer-Verlag London Limited 2010
383
384 A.N. Keeling
• Non-fatal rupture: this has variable clinical manifestation depending on the site
and severity of bleeding.
• Site of bleeding: hematemesis, hemobilia, hematochezia, bleeding from surgical
drain.
• Severity of bleeding: hemodynamic compromise with abdominal pain indicates
massive rupture.
• Herald bleeding: a small warning bleed is not uncommon; this can presage
massive bleeding and is an indication for urgent intervention.
• Rupture into the portal vein results in arterio-portal fistula and severe portal
hypertension.
• End-organ complications
• Ischemia (upper GIT ischemia, pancreatitis).
• Infarction secondary to distal embolization of thrombus.
• Abscess formation secondary to super infection of end-organ infarct.
Specific Sites
Splenic Artery
• Incidence of 0.78%
• Females > males in a 4:1 ratio
• 20% of patients have multiple aneurysms
• 70% are true aneurysms
• Etiology:
1. Portal hypertension
2. Inflammatory process – 10% of chronic pancreatitis
3. Trauma
4. Mycotic
5. Other risk factors: essential hypertension, polyarteritis nodosa, fibrodysplasia, systemic lupus erythematosis, Ehlers–Danlos syndrome and
neurofibromatosis
6. Repeated pregnancies
Hepatic Artery
• Male > females in a 2:1 ratio
• Similar etiology to splenic arterial aneurysms, with >20% secondary to trauma
or iatrogenic (surgery, percutaneous biopsy, liver transplant) causes
• 80% extra-hepatic location
• >50% false aneurysms
• Presentation: asymptomatic or non-specific pain
Rupture – Hepatobiliary tract: hemobilia, jaundice, GI bleed
Peritoneal cavity: abdominal pain, hypotension, abdominal distension
39 Embolization of Visceral Arterial Aneurysms 385
• Mortality rate of rupture >35%, which exceeds the mortality rate associated with
splenic artery rupture
Celiac Artery
• Males = females
• Etiology: arteriosclerosis and medial degeneration, trauma, dissection,
Takayasu’s arteritis, syphilitic aneurysms (now uncommon)
• Lifetime risk of rupture of about 6%
Superior Mesenteric Artery
• Males = females
• Etiology: septic emboli in about one-third
Other causes: arteriosclerosis, dissection, polyarteritis nodosa, pancreatitis, bil-
iary tract disease, neurofibromatosis, trauma
• Some SMA aneurysms are termed high-flow aneurysms and result from compromise of the celiac artery. In these situations, treating the underlying cause (the
celiac axis stenosis) will usually cause the aneurysm to regress.
• Clinical manifestations: >90% are symptomatic, most commonly pain and
gastrointestinal bleeding. Acute mesenteric ischemia may result from thromboembolism.
• Intervention is recommended for all patients.
Diagnostic Evaluation
Clinical
• Asymptomatic vs symptomatic
• Double-rupture phenomenon
• Risk factor for rupture – pregnancy
• Abdominal bruit on auscultation
Laboratory
• Anemia if ruptured, abnormal LFTs if biliary tract obstruction is secondary to
hemobilia, raised amylase/white cell count/inflammatory markers if associated
with pancreatitis.
386 A.N. Keeling
Imaging
• Plain film: aneurysmal sac calcification can be identified within the right or left
upper quadrant.
• Ultrasound (US): echopoor fluid-like sac structure can be identified. Can be
echogenic if the wall is calcified or isoechoic if there is thrombus within the
sac. Associated conditions can be diagnosed (e.g., pancreatitis, abscess).
• Color Doppler: flow within the sac can be identified. Ying-Yang sign can be
elicited in a pseudoaneurysm. Feeding and draining vessels can sometimes be
identified.
• MDCT and MDCTA: better s patial resoultion has enabled accurate diagnosis of
aneurysm location and morphology, the parent artery anatomy, potential etiology,
and associated end-organ complications.
• MRI and MRA: aneurysm location and morphology can be determined; the parent
artery anatomy, potential etiology, and associated end-organ complications can
also be determined. Spatial resolution is not as good as CT.
• DSA: remains the gold s tandard. Enables treatment planning because afferent and
efferent vessels can be identified, any vessels arising from the sac can be seen,
and allows intervention at the same session.
Indications for Treatment
• Presentation: rupture is an emergency asymptomatic, incidentally diagnosed may
need to be treated if criteria below are met.
• Size >2 cm is usually treated.
• Etiology: all pseudoaneurysms should be treated due to rupture risk; some true
aneurysms have an indolent course and can be managed expectantly.
• Morphology: calcified wall does not confer protection from rupture.
• Location: will determine type of treatment undertaken.
• Number: increased number is associated with an increased rupture risk.
• Presence of end-organ complications: infarcts, ischemia, abscess formation,
associated inflammation.
• Presence of high flow states:
• Pregnancy increases blood flow through the aneurysm and estrogens affect the
elastic lamina of the wall, both increasing the risk of sac growth and rupture.
Maternal death with rupture = 75%, fetal death = 95%.
• Cirrhosis with portal hypertension: associated with splenic arterial aneurysms,
increasing the risk of rupture and death.
• Liver transplantation: risk of rupture 40–80%.
Contraindications to Treatment
• Size: <2 cm in asymptomatic, single, true aneurysm without associated high
flow state/end-organ complications/inflammation is a relative contraindication
39 Embolization of Visceral Arterial Aneurysms 387
for treatment. However, the decision regarding treatment should be made on an
individual patient basis.
Relevant Anatomy
Normal Anatomy ( ≈ 50%)
• Celiac artery: arises from the anterior aspect of the abdominal aorta at T11/12,
divides into splenic artery, common hepatic artery, and left gastric artery.
Common hepatic bifurcates into the gastroduodenal artery and hepatic artery
proper.
• Superior mesenteric artery: arises from the anterior aspect of the abdominal aorta
at T12/L1.
Aberrant Anatomy (≈ 44% with One Arterial Variant, ≈ 6% with Two Arterial Variants)
• Celiac artery: replaced left hepatic artery arising from the left gastric artery; can
have common origin with SMA; arises higher/lower from the aorta; hepatic and
splenic arteries can arise directly from the abdominal aorta.
• Superior mesenteric artery: can have replaced/accessory right/left/common hepatic artery/gastroduodenal artery arising from the SMA.
Equipment
• Catheters: Non-selective: Pigtail, Omniflush; selective: Cobra, SosOmni,
Sidewinder/Simmonds, Rim, Microcatheters.
• Wires : glidewire, hydrophilic, various microwires (0.014).
• Coils: detachable preferred (can be retrieved if operator not satisfied with resting
position), pushable fibered coils. Microcoils may be needed.
• Liquid embolics: glue, Onyx.
• Stent-grafts: self expandable (Viabahn, Fluency, Atrium, Wallstent (stiffer, less
flexible)); balloon expandable: more precise deployment (Jostent (coronary stentgraft, smaller sizes), Advanti, Iscat).
Medication
• Sedation and analgesia: intraprocedural intravenous sedation if required. May
need analgesia and anti-emetic post-procedure to manage post-embolization syndrome. General anesthesia may be useful if using Onyx, which can be extremely
painful.
388 A.N. Keeling
• Anticoagulation: only necessary if using a stent-graft. Recommend aspirin for
life and clopidegrol for 6 weeks – 3 months post-stenting (if stenting performed
electively, can give anti-platelet agents pre-stenting).
Procedure
• Access: >90% from the common femoral artery. Remember the brachial approach
if difficulty with celiac/SMA angulation.
• Angiography: flush aortogram, lateral position to determine origin of celiac/SMA
or aberrant anatomy. Selective angiogram of parent artery to identify afferent/efferent/additional arteries feeding the aneurysmal sac.
• Assessing the aneurysm: location and size of the aneurysm are usually known
from non-invasive angiographic imaging. Determine if the aneurysm occurs at a
parent vessel origin/branch point. Angiographic appearance: saccular/fusiform,
size of neck if saccular, parent vessel caliber/tortuosity/calcification.
• Forming an embolization treatment plan: goal is to completely exclude the
aneurysm from the arterial circulation.
• Pack the sac: with true, saccular, or narrow-necked aneurysms selective
embolization of the sac with coils or glue until fully occluded. (Figure 39.2)
• Sandwich technique: with true/pseudoaneurysm, saccular/fusiform aneurysm,
exclude the aneurysm by coiling the afferent and efferent arteries (i.e., coil the
“front and back door”). (Figure 39.1)
• Stent-graft: with true/pseudoaneurysm, saccular/fusiform aneurysm, exclude
the aneurysm with a covered stent. Ensure the parent vessel is of good caliber
and non-tortorous, with an adequate proximal and distal artery for landing
zones/guidewires/sheath/guidecath. Stent grafts are generally oversized by
≈20%.
• Combination: use both the “pack the sac” and “sandwich” techniques, if feed-
ing vessels supplying the sac/very large sac/failed coiling or if loss of access
of efferent artery. (Figure 39.2)
• Balloon remodeling: used to pack the sac with wider neck to prevent coil/glue
protrusion. Microcatheter is placed into aneurysm and occlusion balloon
inflated across the neck of the aneurysm. Aneurysm can be packed with coils
to exclude parent artery or Onyx can be used to form a cast of the aneurysm.
(Be careful to use a microcatheter compatible with Onyx as non-compatible
microcatheters can disintegrate.)
• Balloon occlusion: inflate balloon proximally to reduce flow in order to
prevent distal coil migration during sandwich embolization.
• Immediate post-procedure care: vital signs and clinical observation for recurrent
bleeding from the aneurysm. Arterial access site observation, analgesia, antiemetics, IV fluids for post-embolization syndrome. Image before discharge to detect
sac re-perfusion – modality depends on site.
• Long-term follow-up: clinical evaluation, imaging if re-perfusion suspected,
repeat embolization if rupture.
39 Embolization of Visceral Arterial Aneurysms 389
Results
• There are a number of reasonably sized series in the literature reporting outcome
for endovascular therapy of visceral aneurysms.
• Technical success varies from 93 to 98%.
• Agents used are mainly coils (detachable and pushable), glue and more latterly,
Onyx.
• Post-embolization syndrome occurred in 6–30%.
• Sac reperfusion occurred in 6–7% requiring reintervention.
• 8% periprocedural mortality reported in one series (from aneurysm rupture).
Alternative Therapies
• Percutaneous thrombin injection: if suitable anatomy (i.e., narrow neck, suitable
location, clear and safe access route). Thrombin injection may be useful in splenic
artery aneurysms associated with pancreatitis.
After failed or partial endovascular embolization result
May deploy coils via percutaneous needle approach if thrombin alone fails.
Use US/CT/endoscopic US as image guidance methods
Potential complications: distal embolization via aneurysmal neck if wide.
Sac reperfusion via parent vessel or side branch feeders.
• Surgery: bypass with vein graft or prosthetic graft (prosthetic grafts have lower
risk of occlusion than saphenous vein grafts).
Direct aortic reimplantation of celiac or superior mesenteric artery for proximal
aneurysms.
• Conservative: watchful waiting if small size (<2 cm), no possibility of pregnancy, true aneurysm, no end-organ complications, and no history of portal
hypertension.
Specific Complications: Methods to Reduce Complications
• Rupture of aneurysm during embolization: avoid packing the sac of a pseudoaneurysm.
• End-organ infarction: try to preserve some end-organ blood supply.
• Abscess formation within infarcted tissue: prophylactic antibiotics.
• Post-embolization syndrome: antiemetics, analgesia, in fluids.
• Recurrence/reperfusion of sac: follow-up imaging to detect, embolize to com-
plete stasis during first procedure.
• Stent-graft migration/kinking/occlusion/thrombosis: routine anticoagulation.
• Distal coil embolization: use long coil initially to form a nest.