Abdominal Aortic Aneurysm Screening
Transcript of Abdominal Aortic Aneurysm Screening
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Author's Accepted Manuscript
Abdominal Aortic Aneurysm Screening
Alexis D. Hall M.D., Patti Barkley B.S.N., M.S.N.,Karen Broadbent B.S.N., R.V.T., Tam T.T. Huynh M.D.
PII: S0037-198X(14)00046-7DOI: http://dx.doi.org/10.1053/j.ro.2014.10.003Reference: YSROE50490
To appear in: Seminar in Roentgenology
Cite this article as: Alexis D. Hall M.D., Patti Barkley B.S.N., M.S.N., Karen Broadbent B.S.N., R.V.T., Tam T.T. Huynh M.D., Abdominal Aortic Aneurysm Screening, Seminar inRoentgenology, http://dx.doi.org/10.1053/j.ro.2014.10.003
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Abdominal Aortic Aneurysm Screening
Alexis D. Hall, M.D., Patti Barkley, B.S.N., M.S.N.1, Karen Broadbent, B.S.N., R.V.T.2, and Tam T.T. Huynh,
M.D.,1, 3
1Department of Thoracic and Cardiovascular Surgery, The University of Texas – MD Anderson Cancer
Center, 2Department of Cardiovascular Surgery, The Houston Methodist Hospital, 3Department of
Interventional Radiology, The University of Texas – MD Anderson Cancer Center,
Houston, Texas.
Corresponding Author:
Tam T.T. Huynh, MD.
Professor
Department of Thoracic and Cardiovascular Surgery
The University of Texas – MD Anderson Cancer Center
1515 Holcombe Blvd., Unit 1489
Houston, TX 77030‐4009
Tel (713) 794‐1477
Fax (713) 794‐4901
Email: [email protected]
Submitted to Seminars of Roentgenology, guest editor, M. Truong, M.D.
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ABSTRACT:
Abdominal aortic aneurysm (AAA) currently ranks as the 15th leading cause of death in the US.
Most patients with AAA are asymptomatic until rupture. Elective AAA repair is the most effective
therapy to prevent death from aortic rupture. In this review, we discuss the rationale and examine the
role of ultrasound screening to detect AAA in the population. We conclude that ultrasound screening
reduces the death rate caused by AAA rupture, particularly, in at‐risk men and women 65‐75 years
of age who have smoked tobacco or have family history. More studies are needed to elucidate the
role of AAA screening in the octogenarians and women.
Introduction
Abdominal aortic aneurysm (AAA) is a potentially life‐threatening condition causing
approximately 16,000 deaths per year in the United States (US) 1. Most patients with AAA are
asymptomatic until rupture, which is uniformly fatal if untreated. It is estimated that greater than fifty
percent of patients who sustain AAA rupture will die at home, and 30‐50% of those who are taken to the
hospital will not survive to discharge 2. Elective AAA repair is the most effective therapy to prevent
death from aortic rupture. A large body of evidence exists supporting the usefulness of screening to
detect AAA in reducing the risk of death from AAA rupture in asymptomatic patients 3. Several
organizations in the US and other countries have established recommendations for AAA screening. The
following is a review of the available evidence which serves as the rationale for screening to detect AAA
in asymptomatic patients.
By definition, the aorta is aneurysmal when its diameter exceeds 3 cm or 1.5 times its original
size or normal adjacent aorta 4. The most commonly affected aortic segment is below the branching of
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the renal arteries (also commonly known as infra‐renal AAA; figure 1). Only five percent of AAA involves
the renal or visceral arteries. AAA is a relatively uncommon condition in the general population. In a
longitudinal population‐based study over 30‐year review of the stable Midwest area of Olmsted county
in the US, Bickerstaff and co‐authors identified 296 persons with abdominal aortic aneurysm (196 men
and 100 women), and reported an incidence of 21.1 per 100,000 person‐years for the disease with an
estimated rupture incidence of 3.5 per 100,000 person‐years 5. Bengtsson and Bergqvist reported an
incidence of 5.6 per 100,000 person‐years for ruptured abdominal aortic aneurysms in a 16‐year period
in the city of Malmo in Sweden (1971‐1986); specifically, the rupture incidence was 8.4/100,000 men
and 3/100,000 women 6. AAA has ranked as the 10th to 19th leading cause of death in the US over the
last several decades. More recently, according to the Center for Disease Control (CDC) and National
Center for Health Statistics (NCHS), aortic aneurysm and aortic dissection (including thoracic and
abdominal aortic aneurysms and dissection) ranks as the 15th most common cause of death in the US in
1999 1. National data regarding deaths due solely to AAA is not well documented. In 1999, aortic
aneurysm and dissection caused 15,807 deaths in the US (0.7% of total deaths; rate 5.8 per 100,000
population) 1. The estimated prevalence of AAA ranges from 4.1% to 14.2% in men, and from 0.35% to
6.2% in women 7. The natural history of AAAs is that of slow growth until rupture or death. The rate of
growth of AAAs is variable with reported average rate of approximately 0.3 to 0.4 cm per year 8. In
particular, the initial aneurysm size is an important predictor of the rate of growth, with larger
aneurysms growing at a faster rate than smaller ones. Other complications of AAAs such as distal
embolization or aortic thrombosis are uncommon (less than 5% of cases).
Risk Factors and Etiology
The development of AAA is commonly associated with atherosclerosis and an infiltration of
inflammatory cells into the media and adventitia, although the underlying cause and pathogenesis
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remain to be elucidated. AAAs demonstrate extensive structural remodeling, which is characterized by
the degeneration of extracellular matrix, destruction of elastic lamina, apoptosis of vascular smooth
muscle cells, and reduction in elastin concentration 9. AAA tissues have increased levels of MMP‐2 and
MMP‐9 compared with normal aortic tissues10. The majority of inflammatory cells recovered from AAA
tissues are CD4‐positive lymphocytes (predominantly T cells followed by B cells) 9. These inflammatory
cells are thought to be involved in the destruction of extracellular matrix and apoptosis of vascular
smooth muscle cells that lead to the formation of AAA.
Risk factors associated with the development of AAA include advanced age, male gender, white
race, tobacco smoking, hypertension, hyperlipidemia, atherosclerotic disease, and family or personal
history of aortic aneurysms 5, 7, 8, 11. AAA is generally detected in the 6th and 7th decade of life, with
women typically older than men. The prevalence of AAAs ranges from 1.3% in men 45 to 54 years of age
to 12.5% in older men 75 to 84 years of age12. For women, the prevalence ranges from 0% in the
youngest to 5.2% in the oldest age groups12. To date, there are no studies demonstrating gender
differences in the pathogenesis of thoracic versus abdominal aortic aneurysms. However, the gender
distribution shows a significantly higher ratio of men to women for abdominal aortic aneurysms, 2 to 5:
1, compared to approximately 1.7: 1 for thoracic aortic aneurysms 5, 13. Tobacco smoking can increase
the risk of developing AAA by 7 times 14. Family history of a first degree relative affected with AAA was
found in 12‐19% of patients undergoing AAA repair 15. Roughly 85% of patients with a femoral artery
aneurysm and 62% of those with a popliteal aneurysm will also have AAA. Conversely, 14% of patients
with AAA also have a femoral or popliteal aneurysm16. For unclear reasons, African Americans and
diabetic patients have a lower incidence of AAA7.
Risk of Rupture
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The operative mortality for emergency repair of ruptured AAA (figure 2) far exceeds that for
elective AAA repair, with rates as high as 50‐80% compared to less than 5% for elective repairs in most
series17‐19. Due to the dismal outcomes for patients with ruptured AAA, elective AAA repair is generally
recommended when the risk of rupture exceeds the risks associated with repair. To date, the best
predictor for AAA rupture correlates with size of AAA. In general, the estimated annual risk of rupture
rate is approximately 0.5% for AAA diameter less than 4.0 cm, 1% for 4.0 to 4.9 cm, 11% for 5.0 to 5.9
cm, and 26% for 6.0 to 6.9 cm, and greater than 40% for larger AAA 5, 6, 20‐22. While rupture risk is
predominantly associated with aneurysm size, multiple other factors have been shown to be associated
with an increased risk of rupture including, the rate of aneurysm growth, familial AAA, elevated mean
blood pressure, low forced expiratory volume in 1 second (FEV1), current smoking, female gender, and
immunosuppression in patients with prior solid organ transplantation 23‐25. In a study of 24,000
autopsies performed over a 23 year period, it was found that about 40% of AAA over 5 cm ruptured 26.
In addition, this study also revealed that 13% of AAA smaller than 5cm ruptured, and 40% of AAA
measuring 7 cm to 10 cm had not ruptured 26. The effects of other factors on AAA risk of rupture are
being investigated, including wall stress, expansion rate, intraluminal thrombus thickness, wall stiffness,
and wall tension 27, 28.
Elective AAA Repair
With the increase use of diagnostic CT and MRI imaging studies in clinical practice, the finding of
an incidental AAA in an asymptomatic patient can pose a treatment dilemma. The risks of elective
repair are weighed against an estimated rupture risk for each individual patient, as well as the likelihood
that rupture will occur before death from other causes. Several large studies have compared the results
of elective open surgical AAA repair versus endovascular aortic aneurysm repair (EVAR; figure 3). The
reported in‐hospital mortality rates for elective AAA repair are low, and range between 3% and 5% for
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open surgical repair, and 1 to 2% for EVAR 18, 19. The long‐term survival curves following the two
different treatment approaches converge after 2‐3 years; but EVAR is associated with a greater number
of post‐repair interventions, most of which are catheter‐based 29, 30. Reported rates of complications
following open AAA repair vary, and higher rates have been associated with low hospital volume (< 35
AAA repairs per year) or lack of fellowship‐training by the surgeon 18, 31, 32. Across the US and Europe,
EVAR has been widely adopted as the treatment of choice for the majority of patients with infra‐renal
AAA since the early 2000 (figure 4). Open surgical AAA repair is currently reserved for patients deemed
not suitable for endovascular approach due to anatomical reasons, such as short infra‐renal aortic neck
or associated conditions requiring surgical intervention (figure 5).
Ultrasound as a Screening Tool
Physical examination of the patient has low sensitivity in detection of AAA. Palpation can detect
aneurysms greater than 5 cm in up to 76% of patients, but can only pick up 29% of aneurysms smaller
than 4 cm 33. Reported rates of sensitivity and specificity for focused physical examination to detect
aneurysms at least 5 cm are estimated around 80 and 85 percent, respectively, with moderate inter‐
observer agreement 33, 34. Ultrasound detects the presence of an asymptomatic AAA accurately,
reproducibly, at low cost, and with little risk of harm to patients (figure 6). Ultrasound measurement of
the diameter of the infra‐renal aorta has a sensitivity and specificity of 94‐100% and 98%‐100%,
respectively 35, 36. In 1% to 3% of patients, bowel gas or adipose tissue obstructs visualization of the
retroperitoneal aorta 37, 38. Inter‐observer difference for ultrasound measurements is relatively low, but
increased abdominal girth can diminish test accuracy 39. Measurement of AAA diameter by ultrasound
may not be as precise when compared to CT scan imaging 40. Admittedly, the quality of ultrasound
imaging is highly dependent on the skill and experience of the operator. However, the ease of
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portability, lower cost, absence of radiation exposure, and lack of contrast infusion have made high‐
quality vascular ultrasound preferable to CT scan in AAA screening and surveillance (figure 7) 41.
CT and MR Angiogram
Due in part to institutional level of expertise, CT angiogram is by far the most frequently used
imaging modality to evaluate for aortic disease in our center. High spatial resolution of the multi‐slice
helical CT scanner provides remarkable images of the aorta and adjacent solid organs. Image acquisition
is rapid with CT imaging, and scanning of the entire aorta from the chest to pelvis can be completed
within minutes, compared to the much longer scanning time with MR and ultrasound imaging. CT
angiogram is the modality of choice for operative planning prior to EVAR and open AAA repair. We also
prefer using CT angiogram for surveillance of patients with small AAA and after EVAR. Alternatively, in
selective patients, MR angiogram can be used for assessing the abdominal aorta (figure 8). Although MR
imaging has lower spatial resolution than CT, it obviates the risks related to radiation or use of
intravenous iodinated contrast.
AAA Screening Clinical Trials
The Chichester, United Kingdom, AAA screening program was the first randomized controlled
trial of ultrasound screening for AAA 42‐44. From 1988 to 1993, 15,775 men and women, aged 65‐80
years, were randomized to either invitation for ultrasound screening or an age and gender matched
control group. During the study period, patients with an AAA 3‐4.4cm in diameter were rescanned
annually, whereas patients with aneurysms 4.5‐5.9cm in diameter were rescanned every 3 months.
Patients were referred for surgery if they had aneurysms 6 cm or greater, aneurysm growth rate greater
than 1 cm per year, or symptom development. Of those invited for screening, 68.4% accepted. AAA was
diagnosed in 218 persons (4% of all persons screened), and 178 were men. Ninety persons found to
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have AAA met criteria for surgical repair, and 39% of those had surgery (35 out of 90). After 5 years of
follow‐up, there was a statistically significant 55% reduction in AAA rupture in the group of male
patients who underwent screening compared with the control group (9 ruptures out of 3205 male
patients screened, 0.28% vs 20 ruptures in the 3228 male control patients, 0.62%). After 10 years of
follow‐up, there remained a 21% decrease in AAA related mortality in the screened male patients.
However, there was no risk reduction in AAA rupture between the screened and control groups of
women at 5 and 10 years follow‐up. Of the male patients invited for screening, AAA related deaths
accounted for 9 of the 532 deaths (1.5%), whereas it accounted for 16 of the 508 deaths (3.1%) in the
control group.
The second randomized trial of ultrasound AAA screening was designed similarly and conducted
in Viborg, Denmark 45‐47. From 1994 to 1998, all men in the county aged 65 to 73 were randomly
assigned to either receive an invitation for abdominal ultrasound screening or to a control group. Of the
6339 men invited for screening, 76% accepted (4843), and 4% of these had an AAA (191), while 0.5%
(24) had an AAA greater than 5cm. Men with AAA measuring 5 cm or more were referred to a vascular
surgeon for repair, whereas men with smaller AAA were invited to consult with a doctor and receive
yearly surveillance exams. During the 5 year follow‐up, 51 additional patients were referred for surgery,
and a total of 67% of the men referred underwent an elective repair (50/75 men). After 5 years,
comparison of the hospital outcomes revealed a 70% reduction in the number of ruptured AAAs, a 74%
reduction in the number of emergency operations for AAA, and an overall 68% reduction in hospital
deaths in the group of screened men compared with the control group. Expectedly, the group of
screened patients had a higher number of operations, 51% increase in total operations, 278% increase in
elective operations.
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The third randomized trial of ultrasound screening for AAA, the Multicenter Aneurysm Screening
Study (MASS), recruited 65‐74 year‐old men from offices of family physicians and health authority lists
from 1997 to 1999, in four counties in the United Kingdom 48‐50. Subjects had to be deemed fit by their
physicians. The participants were randomly allocated to screening or to a control group. Patients with
AAA 3‐4.4 cm received yearly ultrasound exam, those with AAA 4.5‐5.4 cm received ultrasound exam
every 3 months, and those with aneurysms 5.5 cm or greater were referred to a vascular surgeon for
repair. Eighty percent of the patients invited for screening accepted (27,147 out of 33,839), revealing
aneurysms at least 5.5 cm in 12% of the detected AAAs (166 out of 1333). After 4 years, there was a
significant reduction in AAA related death in the screened group, with 65 AAA related deaths compared
to 113 in the control group. There was also a significant reduction in nonfatal ruptured AAA in the
screened group, with 17 compared to 27 in the control group. There was no statistically significant
difference in all‐cause mortality, however. Overall, AAAs accounted for 2‐3% of the deaths (2% in the
screened group, 3% in the control group). The men who accepted the invitation for screening were
generally healthier than those who refused screening; they had a lower AAA related death rate, lower
incidence of ruptured AAAs, and lower all‐cause mortality (24.1 vs 46.4 per 10,000 person years). After
10 years, there was a 45% relative mortality risk reduction in the screened group.
The fourth randomized clinical trial of ultrasound screening for AAA included 41,000 men aged
65 to 83 years living independently in Perth, Australia between 1996 and 2001 51. The participants were
randomly assigned to a screening or control group, and those invited to screening received a
prearranged screening exam assignment by mail. The control group patients were not contacted. Of
the 19,352 patients allocated to screening, 69.7% participated, and 7.2% were found to have an AAA
(875), 7% had aneurysms greater than 5.5cm (61), and a total of 107 patients underwent repair (0.6%).
In the control group, 54 patients (0.3%) underwent AAA repair. At the end of 5 years follow‐up, 18 men
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in the screening group and 25 in the control group died from AAA. This yielded a mortality ratio of
0.61(95% confidence interval 0.33‐1.11), and the relative risk of death was not significantly different
between the two groups. In a subgroup of men aged 65 and 74 years, a benefit was seen where the
mortality ratio was reduced to 0.19 (95% confidence interval 0.0 – 0.89). The investigators concluded
that at a whole population level screening for AAA was not effective and did not reduce overall death
rates.
The US Preventive Task Force (USPTF) reviewed these large randomized AAA screening trials and
other available evidence on AAA screening in 2005. They concluded that AAA screening in men age 65 to
75 years does not appear to be associated with significant physical or psychological harms, but reduces
AAA‐related mortality, even though major treatment harms can include an operative mortality rate of
2% to 6% and significant risk for major complications 52. In our opinion, the modern AAA treatment
patterns have evolved since these screening trials were conducted, with a much larger proportion of
patients having endovascular repair rather than open surgical repair, which conceivably would produce
greater benefits than the results in these studies. Clearly the patients who would benefit the most from
screening are those who would have developed a ruptured AAA in their lifetime, but are diagnosed in
time to have it repaired electively. On the other hand, screening of the general population can yield
many undiagnosed, small aneurysms that are unlikely to rupture, exposing patients to potentially
unnecessary interventions, stress and expense. A Canadian study found that 80% of AAA cases could be
identified by studying only 17% of patients, selecting patients based on risk factors of age, smoking,
blood pressure, body mass index, history of heart disease, and serum high‐density lipoprotein 53.
Unfortunately, there is a dearth of studies on AAA screening for women and its benefit in women
remains to be proven.
Small AAA Surveillance
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For those patients who have a diagnosis of AAA but do not meet requirements for repair,
continued surveillance is indicated, as well as optimization of medical comorbidities to decrease the
associated cardiovascular risk and to limit the rate of aortic expansion. The optimal AAA surveillance
frequency has not been clearly distinguished in clinical trials. While some authors have concluded that
there is no need to repeat imaging of aneurysms less than 3 cm, others have shown significant growth of
small aneurysm during long‐term follow up. In a 12 year analysis of 1121 small aneurysms in 65 year old
men, McCarthy et al. showed that nearly 14% of patients with an initial AAA 2.6 cm to 2.9 cm exceeded
5.5 cm at 10 years 54 . In addition, approximately 2% of aneurysms 3 to 3.4 cm reached 5.5 cm at 3
years, and more than 10% of those between 3.5 cm and 3.9 cm reached 5.5 cm, required surgery within
2 years, and 1.4% ruptured 54. Both the UK Small Aneurysm Trial 55 and the Aneurysm Detection and
Management (ADAM) in North America 56, 57 studies demonstrated that surveillance of aneurysms until
diameter exceeds 5.5 cm is safe and associated with less than 1 % rate of rupture. In both studies,
patients in the surveillance group had repeated imaging every 3‐6 months. Brady et al. followed over
1700 patients for an average of nearly 2 years and estimated that for a patient with a 4.5 cm AAA, the
risk of enlargement to 5.5 cm was less than 1% during a 12‐month period 58. In our practice, we
recommend surveillance imaging every 12 months for AAA less than 5 cm, and a shorter interval period
of 6 months for AAA 5 cm or larger.
For each individual patient, the treating physician compares the risk of elective repair to the
estimated rupture risk, as well as the likelihood that rupture will occur before death from other causes.
In an aging population, this last point is important in decision making regarding screening and
surveillance. Patients may view the AAA diagnosis as a “ticking bomb”, causing them additional stress,
especially when the patient does not meet criteria for elective aneurysm repair 59. Risks associated with
elective repair must also be considered in a screening and surveillance program, as more patients will
undergo elective repair. For AAA smaller than 4 cm, some argued against surveillance as the rate of
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rupture is very low and that these aneurysms are unlikely to become clinically significant during the
patient’s remaining lifetime 60‐63. While there are little known physical harms associated with the use of
ultrasonography in adults, other harms due to surveillance may exist 64. Surveys conducted in the MASS
and Viborg trials revealed that invited participants with positive ultrasound findings had lower initial
self‐rated health status 45, 48. In contrast, in the Gloucestershire study, no differences were found in the
general health measures or anxiety levels between men with normal or aneurysmal aortas prior to or
after screening 65.
Recommendations and Guidelines
Building on the evidence regarding the incidence of AAA, high lethality of ruptured AAA, relative
low cost of screening, potential harms of AAA treatment, and life expectancy, several recommendations
and guidelines have been formulated regarding ultrasound screening for AAA. There are variations in
the published recommendations and guidelines, primarily, on limiting screening to at‐risk patients based
on age, gender, use of tobacco, and family history of AAA.
U.S. Preventive Services Task Force 52, 66, 67
In 2005, The USPTF recommends a one ‐time screening for AAA by ultrasound in men aged 65‐
75 who have ever smoked tobacco, and selectively in non‐smokers 65‐75 year‐old men with family
history or other risk factors for AAA. It provides no recommendation for or against screening in women
who have ever smoked, but recommends against screening women who have never smoked tobacco.
The USPTF recently updated their recommendation in 2014 67.
SAAVE Act and Medicare 68
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The US congress passed the Medicare Screening Abdominal Aortic Aneurysms Very Efficiently
(SAAAVE) Act in 2006, which provides Medicare coverage for a one‐time AAA ultrasound screening for
at‐risk people. Eligible people are (1) men and women with family history of AAA, and (2) men age 65 to
75 who have smoked at least 100 cigarettes in their lifetime. Initially, this benefit was linked to the
Welcome to Medicare Physical Exam at age 65 but a subsequent amendment removed this link as a
requirement.
The Canadian Society for Vascular Surgery 69
Currently, the Canadian Society for Vascular Surgery recommends all men aged age 65 to 75 to
undergo screening for AAA. In addition, it recommends selective screening for those at high risk for AAA,
including women over age 65 at high risk secondary to smoking, cerebrovascular disease and family
history, and men less than 65 with a family history of AAA.
Society of Vascular Surgery 70
SVS recommends one‐time screening for AAA by ultrasound in all men 65 years of age and older,
or at age 55 in patients with a family history of AAA. Women aged 65 or older with a history of smoking
or family history of AAA should also receive ultrasound screening. Follow‐up ultrasound surveillance
should be performed at 12 month intervals for patients with an AAA 3.5 cm to 4.4 cm in diameter. The
frequency of surveillance should be increased to every 6 months for patients with aneurysms between
4.5 cm and 5.4 cm.
Summary
In summary, abdominal aortic aneurysm (AAA) is a relatively uncommon but highly lethal
disease when it ruptures. Ultrasound screening can detect AAA in otherwise asymptomatic patients,
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and effectively reduces the death rate caused by rupture, particularly, in at‐risk men and women
65‐75 years of age who have smoked tobacco or have family history. More studies are needed to
elucidate the role of AAA screening in the octogenarians and women.
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FIGURE LEGENDS:
Figure 1. Coronal CT image of AAA
Infra‐renal AAA is the most common type of aortic aneurysm. Asterisk (*) denotes the AAA. Arrow
points to the right renal artery.
Figure 2. Ruptured AAA
(A) Axial CT image shows contained rupture AAA with (*) retroperitoneal hematoma. (B) Intra‐operative
photograph of the abdominal cavity displaying the undisturbed (*) contained hematoma and blood
infiltrating the bowel mesentery.
Figure 3. Endovascular Abdominal Aortic Aneurysm Repair (EVAR)
Completion image of a modular 2‐piece endografts after EVAR; (*) denotes main body of endograft.
White arrows points to angiographic catheter and black arrow to super‐stiff wire.
Figure 4. Long‐term Appearance Abdominal Aorta after EVAR
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Axial CT image of large infra‐renal AAA (a) prior to EVAR and (b) 3 years after EVAR with complete
shrinkage of aneurysm sac; asterisk (*) denotes the abdominal aorta.
Figure 5. Surgical Repair of AAA
Example of an AAA not suitable for EVAR and requiring open surgical repair due to short proximal infra‐
renal aortic neck and chronic mesenteric ischemia with occlusion of celiac, superior mesenteric, and
inferior mesenteric arteries. (A) Axial CT image showing angulated short proximal aortic neck of a large
AAA; (B) reformatted coronal image showing the angulation of AAA and an arrow pointing to the arc of
Riolan, which provides collateral flow from a pelvic vessel to a branch of the occluded superior
mesenteric artery (not shown); (C) intra‐operative photograph depicting the (#) bifurcated aorto‐biiliac
graft reconstruction and (*) interposition graft to the superior mesenteric artery.
Figure 6. Ultrasound Imaging of AAA
An example of an infra‐renal AAA viewed on longitudinal axis (2‐D gray scale).
Figure 7. Ultrasound Surveillance of EVAR
Longitudinal view of AAA image with Doppler colorflow shows satisfactory appearance of (#) aortic
endograft, (*) thrombus inside aneurysm sac, and arrow pointing to a type II endoleak, which is likely
due to retrograde flow in the inferior mesenteric artery.
Figure 8. MR Angiogram
MR Angiogram imaging shows focal dissection of abdominal aorta with mild dilatation on (a) axial and
(b) 3‐D reformatted views – arrow pointing to focal intimal flap.
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Fig 1
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Fig 2a
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Fig 2b
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Fig 3
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Fig 4a
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Fig 4b
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Fig 5a
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Fig 5b
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Fig 5c
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Fig 6
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Fig 7
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Fig 8a
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Fig 8b