Download Interventional Radiology and Endovascular Repair of Abdominal

Ralph Vetters
Gillian Lieberman,
November 2000
Interventional Radiology and
Endovascular Repair of
Abdominal Aortic Aneurysms
Ralph Vetters, Harvard Medical School - Year III
Gillian Lieberman, MD
Ralph Vetters
Gillian Lieberman,
Our Patient: J.M.
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68 year old male
Divorced, lives alone in a Boston rooming house
Mason and member of the Bricklayers Union
Tobacco: occasional pipe, no cigarettes last 20
years
• History of alcoholism - sober for 28 years
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Ralph Vetters
Gillian Lieberman,
Significant Medical History
• Family history of coronary heart disease and myocardial
infarction in two brothers
• 1997 MI treated by Percutaneous Transluminal Coronary
Angioplasty (PTCA) and stent
– LAD 30-40% occluded, RCA 30-40% occluded
• 1998 second angioplasty for stenotic RCA
• Hypertension and hypercholesterolemia
• Chronic inactive Hepatitis C
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Ralph Vetters
Gillian Lieberman,
Incidental Finding
In June, 1999, an ultrasound obtained at
an outside hospital to evaluate
hepatobiliary status serendipitously
demonstrated an abdominal aortic
aneurysm (AAA).
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Ralph Vetters
Gillian Lieberman,
Menu of Tests for Imaging AAA
1. Ultrasound
2. CT/CTA
3. MRI/MRA
4. Conventional angiography (invasive)
5. Abdominal plain film (Insensitive, high
false negative, need densely calcified
walls).
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Ralph Vetters
Gillian Lieberman,
Ultrasound as a Screening Modality
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non-invasive, may be performed at bedside
– Can detect free peritoneal blood
– Unable to detect leakage, rupture, branch artery involvement
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Air-filled bowel may block imaging
– Pressure of transducer or positional change improves imaging
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98% diagnostic accuracy in asymptomatic patients
100% accuracy in symptomatic cases (palpable abdominal mass,
tachycardia, severe abdominal pain)
Monitor change in aneurysmal diameter: best in axial plane
– Normal: 2 -3 cm tapering to 1.5 cm at bifurcation
– >3 cm is abnormal
– 5 - 6 cm an indication for medical intervention
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Ralph Vetters
Gillian Lieberman,
Example of AAA on Ultrasound
Identifying the Aorta
Sagital View:
4.93 cm AAA
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Axial view:
4.78 cm AAA
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Thicker than inferior vena cava
White echodense walls
Pulsatile, not undulating
Not compressible with transducer
Located to left and smaller than
IVC
Normal lumen is anechoic
Thrombi moderately echogenic,
echogenicity changing with
thrombus age
Calcified plaques in wall produce
shadowing
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Both images:
Ralph Vetters
Gillian Lieberman,
MRI and CT
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MRI
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Images comparable to CT without contrast or radiation
Better than CT at imaging branch vessels
Not suitable for unstable patients
High cost
CT:
– High sensitivity (100%)
– Better than US at defining aorta size, length, involvement of visceral
vessels, leakage
– 3 dimensional imaging
– Needs technician
– Higher cost
– longer study time
– exposure to contrast and ionizing radiation
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Ralph Vetters
Gillian Lieberman,
J.M.’s Clinical Course
• J.M. asymptomatic at first detection of AAA in June, 1999.
• January 4, 2000 follow up ultrasound:
AAA diameter of 4.5 cm
• March 3, 2000 ultrasound (complains of backache):
AAA diameter of 5.1 cm
• Rate of growth: 0.6 cm in two months.
Let’s look at some case information on AAA to help decide
what treatment J.M. needs.
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Ralph Vetters
Gillian Lieberman,
AAA
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Etiology
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Atherosclerosis
Trauma
Syphilis
Congenital abnormalities
Mycotic aneurysms
Majority found infrarenally
Epidemiology
– Tend to occur in 5th decade of life
– Present in 2% of elderly
population
– 5:1 male to female ratio
Prognosis
– Average rate of expansion of
aneurysm diameter: 0.2 - 0.4
cm/year
– 40% of AAA > 6 cm will
rupture (untreated survival
average 17 months)
– 20% of AAA < 6 cm will
rupture (untreated survival 34
months)
– Dissection risk 2 - 3 times
greater than rupture risk (35%
mortality within 15 minutes)
J.M. clearly needs an intervention.
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Ralph Vetters
Gillian Lieberman,
Operative Option #1: Infrarenal Abdominal
Aneurysmectomy
• 4% operative mortality
• 5 – 10% risk of
complications
Netter, Frank H. Atlas of Human Anatomy, 2nd ed.
Novartis. East Hanover, NJ. 1997
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Bleeding
Renal failure
MI
Stroke
Graft infection
Limb loss
Bowel ischemia
Impotence
Paraplegia
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Ralph Vetters
Gillian Lieberman,
Operative Option #2: Endovascular
Graft-Stent Placement
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Site of
aneurys
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Access via
common femoral
artery
Netter, Frank H. Atlas of Human Anatomy, 2nd ed.
Novartis. East Hanover, NJ. 1997
No laparotomy
No dissection of aorta from
viscera
Minimal blood loss
Decreased incidence of
cardiac/pulmonary
complications
Less hospital time
Decreased cost
Accessable to patients with
previously contraindicated comorbidities
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Ralph Vetters
Gillian Lieberman,
Graft-Stent Devices
Aorto-iliac componenant
Primary access site
Iliac limb
Contralateral access site
Both images this page: D’Ayala, Marcus, et al. Endovascular Grafting for Abdominal Aortic Aneurysms.
Surgical Clinics of North America. 78:5. Oct. 98
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Ralph Vetters
Gillian Lieberman,
Pre-Operative Evaluation: Assessment of
Aorta
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Plaque, thrombus, calcification-free
margin at aortic neck
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Accurate measurement of lumen
length
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to allow passage of placement device
Assess mesenteric vascular disease
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Fillinger, Mark F. New Imaging Techniques in Endovascular Surgery.
Surgical Clinics of North America. 79:3. June, 1999.
to tailor device to patient-specific
pathology - no second chance to stent
to prevent “endoleaks”
External iliacs at least 7 mm in
diameter
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to ensure stent grip on aorta wall
to prevent “endoleaks” at distal and
proximal sites
to prevent graft migration
celiac/SMA stenosis increases risk of
bowel ischemia
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Ralph Vetters
Gillian Lieberman,
Radiological Assessment of J.M.’s Aorta
CT Angiography with 180 cc of Optiray
April 19, 2000
Axial Projection
Radiology Report
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BIDM
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Neck of moderately tortuous aorta seen
3 cm distal to left renal artery
Neck diameter 1.5 x 2.3 cm
Aneurysm length to bifurcation 9.1 cm.
Aneurysm from cephalad edge to
caudal edge of common iliacs: R 13.5
cm, L 13.3 cm
Greatest cross sectional diameter is 5.5
x 5 cm
Right and left common iliacs 1.3 and
1.2 cm in diameter respectively
Length of common iliacs from
bifurcation to internal iliac R 4.4 cm, L
4.2 cm
No free fluid or masses
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Ralph Vetters
Gillian Lieberman,
Multiplanar CTA Reconstruction to
Determine Mid-Lumen Path and Length
Sagital Plane Reconstructions
Radiology Report
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Mid-luminal
path
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Lumen has tortuous hourglass
shape
Aortic bifurcation points left in
7 o’clock direction
Moderate tortuosity of left
external iliac and mild
tortuosity of right external iliac
Determines mid-luminal path,
diameter of lumen, tortuosity,
relative anatomical
Both images
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Ralph Vetters
Gillian Lieberman,
CT 3D Reconstruction
• Visualizes
tortuosity of aorta –
the graft path.
• Illustrates stenoses
– barriers to graft
deployment
• Displays
relationship to
vascular anatomy
in case of
emergency
aneurysmectomy.
BIDM
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Ralph Vetters
Gillian Lieberman,
Limitations of CT Angiography
Fillinger, Mark F. New Imaging Techniques in Endovascular
Surgical Clinics of North America. 79:3. June, 1999.
• Axial slices of CT scan
may transect aorta
obliquely, misrepresenting
true aneurysmal diameter
• Must be complemented by
conventional angiography
with beaded marker
catheter
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Ralph Vetters
Gillian Lieberman,
Conventional DS Angiography: J.M.
150 cc Conray 30%, May 16, 2000
Radiology Report
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BIDMC
Beaded catheter to measure lumen length
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Mild stenosis of left renal artery
Right renal is small in size
Superior mesenteric artery is
patent
Inferior mesenteric is small
Ectatic dilatation of both
common iliacs without
evidence of stenosis
Internal iliacs are patent
Included AP, left lateral, and
oblique exposures
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Ralph Vetters
Gillian Lieberman,
Intraoperative Digital Subtraction
Fluoroscopic Angiography
• Real time acquisition and display of
information
• “Road mapping”
• Less contrast used than in conventional
angiography
• Detects presence of dissections and other
adverse events
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Ralph Vetters
Gillian Lieberman,
Aortograms Visualize Site of Proximal Stent
During Procedure: May 26, 2000
Right renal aertery
Aorta
Left renal artery
Step 1: Straight flush catheter
advanced via left femoral to
renal artery: Aortogram
demonstrates patent renal
arteries and location of
proximal stent site –
“road map.”
Step 2: Catheter advanced
via right femoral to aorta.
Medtronic stent graft device
threaded over guide wire.
Step 3: Repeat aortogram via
left catheter to assure stent is
placed below renal arteries.
BIDMC
Collapsed stent graft
Main body of aneurysm
Loaded placement device:
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Ralph Vetters
Gillian Lieberman,
Deployment of the Stent Graft
Stent graft deployed after
aortogram.
Self-expanding nitinol
AneuRx Medtronic stent
graft responds to body heat
to grip proximal stent site
and distal site in right
femoral artery.
BIDM
Deployment of stent graft
from delivery device.
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Ralph Vetters
Gillian Lieberman,
Deployment of Second Limb of
Stent
Graft
Primary stent
Radiology Report:
“A second limb was brought
through the stent graft from the
left. A pelvic arteriogram on
the left side followed through
the left-sided sheath which
demonstrated an irregular
plaque of the common iliac
artery just proximal to the
takeoff of the mildly stenotic
internal iliac artery. After
delivery of the stent graft,
there was good adaptation.”
BIDM
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Ralph Vetters
Gillian Lieberman,
Intraoperative Intravascular Ultrasonography:
An Alternative to Angiography
Angiography can miss residual stenoses and underdeployed stents. IVUS
immediately post-deployment is more sensitive in detecting these problems.
Examples from two different patients.
Poor approximation after deployment.
Good approximation after 2nd ballooning.
Graft
Lume
Stent
graft
wall
Lumen
of
aorta
at neck
Both images: Fillinger, Mark F. New Imaging Techniques in
Endovascular Surgery. Surgical Clinics of North America. 79:3.
June, 1999.
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Ralph Vetters
Gillian Lieberman,
J.M.’s Post-Operative Progress
• June 20, 2000 – one month post-op – returns to
BIDMC ER with complaints about left groin
incision pain:
– Indurated
– Warm
– Erythema down left thigh
– No discharge or fluctuance
• DX: seroma
• TX: keflex
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Ralph Vetters
Gillian Lieberman,
Post-Op Graft Leak Check:
July 6, 2000
Graft
(6 weeks post-procedure)
Plain Film
• Graft is within aortic
aneurysm.
• Graft extends into iliac
arteries.
• No sign of graft migration.
• Unable to distinguish
leaks or changes in aorta
diameter.
BIDMC
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Ralph Vetters
Gillian Lieberman,
Post-Op Evaluation, Multiplanar and
3D Reconstruction: July 6, 2000
BIDMC
Visualize “fit” of graft.
Confirm placement: no
migration.
BIDM
No kinks
No distortions of anatomy
No significant change in aneurysmal
diameter
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Ralph Vetters
Gillian Lieberman,
Axial CT Post-Op Evaluation of Stent-graft
July 6, 2000
No evidence of
leakage.
No change in
size of aneurysm:
Pre-insertion 5.2
x 5.5 cm. Now
5.1 x 5.5 cm.
Graft in aneurysmal
lumen
BIDM
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Ralph Vetters
Gillian Lieberman,
Patient’s Progress
• July 6 imaging shows excellent result - no
leak.
• July 11, 2000: doing well
– BP: 120/70, HR 70; no JVD; normal S1
and S2.
• Meds: Metoprolol, Zestril, Zocor, aspirin
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Ralph Vetters
Gillian Lieberman,
CT as Standard Post-Op Study
• More sensitive than doppler ultrasound in detecting
leaks.
• More accurate and reproducible diameter
measurements.
• Spiral CT better than conventional:
– Data over entire volume of scan
– Narrow axial reconstructions
– Multiplanar reformats
– “Cine” mode to follow leaks to source
• Follow up at 1, 6 and 12 months then annually.
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Ralph Vetters
Gillian Lieberman,
Example of Endoleak on CT
Thrombus in aneurysm
Graft
Leak from proximal end
Both images this page: D’Ayala, Marcus, et al. Endovascular Grafting for
Abdominal Aortic Aneurysms. Surgical Clinics of North America. 78:5. Oct. 98
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Ralph Vetters
Gillian Lieberman,
Doppler Ultrasound
Doppler ultrasound is a good adjunct to CTA for patients with suspected post-op endoleak.
Flow through
graft lumen –
no evidence
of endoleak.
No flow in
aneurysm
lumen.
Leakage of
blood from
stent lumen
into
excluded
aneurysm
lumen.
Kronzon, Itzhak, et al. Ultrasound Evaluation of Endovascular
Repair of Abdominal Aortic Aneurysms. Journal of the
Society of Echocardiography.
11:4. April 1998.
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Can detect endoleaks, limb
stenoses, occlusions.
Can follow changes in
maximum aortic diameter (CT
has better accuracy).
No radiation.
Cheaper than CT.
85% accuracy in detecting leak
(spiral CT 98% accurate).
Technician dependent
Problems with the obese patient
and gas-filled bowel
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Ralph Vetters
Gillian Lieberman,
References
Billittier IV, Anthony J., et al. “Radiographic Imaging Modalitiesfor the Patient in the Emergency
Department with Abdominal Complaints.” Emergency Medicine Clinics of North America. 14:4.
November 1996.
D’Ayala, Marcus, et al. “Endovascular Grafting for Abdominal Aortic Aneurysms.” Surgical Clinics of
North America. 78:5. Oct. 98.
Fillinger, Mark F. “New Imaging Techniques in Endovascular Surgery.” Surgical Clinics of North America.
79:3. June, 1999.
Katzen, Barry T. “Current Status of Digital Angiography in Vascular Imaging.” Radiologic Clinics of North
America. 33: 1. January 1995.
Kronzon, Itzhak, et al. Ultrasound Evaluation of Endovascular Repair of Abdominal Aortic Aneurysms.
Journal of the American Society of Echocardiography. 11:4. April 1998.
Netter, Frank H. Atlas of Human Anatomy, 2nd ed. Novartis. East Hanover, NJ. 1997
Way, Lawrence W. ed. Surgical Diagnosis and Treatment. Appleton & Lange. Norwalk, CA. 1994.
Santilli, Jamie D. and Steven Santilli. “Diagnosis and Treatment of Abdominal Aortic Aneurysms.”
American Family Physician. 56:4. Sept. 15, 1997. http://www.aafp.org/afp/970915ap/santilli.html
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Ralph Vetters
Gillian Lieberman,
Acknowledgements
Thanks to Daniel Sauerborn, MD for his help in locating
an appropriate index case.
Additional thanks to Elvira Lang, MD.
The End
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