1. Notice anything?
Calcified infrarenal aortic aneurysm – posterior view

2. Easier to see on the lateral
Calcified infrarenal aortic aneurysm – lateral view

3. Abdominal Aortic Aneurysm
September 25, 2009

4. Definition
Aneurysm: irreversible dilation of an artery at least 1.5 times its normal caliber
True aneurysm vs. False aneurysm
Varieties:
Degenerative – due to atherosclerosis, most common type
Traumatic – iatrogenic, catheter-related, penetrating trauma
Poststenotic – Bernoulli’s principle, occurs distally (distal to coarctation, distal to cervical rib in thoracic outlet syndrome, etc.)
Dissecting
Mycotic – infected
Anastomotic – separation between graft and native artery
True aneurysm involves all layers of arterial wall
False aneurysm involves only a portion of wall, or involves surrounding tissue

5. Abdominal Aortic Aneurysm
Fusiform dilation of abdominal aorta > 1.5 times its normal diameter
Incidence: 5% of elderly population >60 years old (6-9 times more common in males)
Relative risk: 11.6% in patients with first-degree relative with known AAA
Risk factors: Atherosclerosis, HTN, smoking, male gender, advanced age, connective tissue disease
Risk factors for rupture: diastolic HTN, initially large size at diagnosis, COPD, symptomatic, recent rapid expansion
White males are at the highest risk

6. Diagnosis Exam Ultrasound Abdominal or back radiographs
Periumbilical palpable pulsatile mass
Ultrasound
Study of choice for initial diagnosis
Used to follow progression of aneurysm over time
Abdominal or back radiographs
Calcifications of aneurysm wall may be seen in ~75% of patients
Abdominal radiograph – incidental finding of AAA

7. Diagnosis CT scan MRI Angiogram
Character, wall thickness, location with respect to renal arteries, presence of leak or rupture
With Contrast for visualization of surrounding vasculature; essential for planning repair
MRI
Greater detail than CT or US regarding lumen, surface anatomy, neck, relationship to renal arteries
Angiogram
Defines vascular anatomy, assess lumen patency and iliac/renal involvement
Especially important in cases of mesenteric ischemia, HTN, renal dysfunction, horseshoe kidney, claudication
Limitation of angiogram – AAAs typically have large mural thrombi, which result in falsely reduced diameter because only the patent lumen is visualized

8. AAA Screening
U.S. Preventive Services Task Force recommends one-time screening by ultrasonography in men age 65 to 75 years who have ever smoked
No recommendation (for or against) screening in men age 65 to 75 who have never smoked, and an explicit recommendation against routine screening in women, based on the relatively low yield
Repeated screening does not appear to be needed

9. Radiograph
Calcifications of aneurysm wall may be seen in ~75% of patients
Best visualized on lateral films; “egg shell” calcifications

10. Ultrasound

11. Ultrasound

12. Ultrasound
AAA with intraluminal thrombus

13. CT scan 12cm abdominal aortic aneurysm Calcification of the wall
Evidence of hemorrhage and surrounding inflammation on left side of abdomen

14. CT with contrast
Large mural thrombus
Calcification of walls

15. CT with contrast

16. CT Three Dimensional Reconstruction

17. Angiogram

18. Triad of Rupture Abdominal pain Pulsatile abdominal mass Hypotension
Straight to surgery vs. CT scan
Known AAA: if hemodynamically unstable, straight to OR
No h/o AAA: if stable, CT first, then OR as needed
Emergent repair of ruptured AAA is a much higher risk operation

19. X-ray
Large, left-sided soft tissue shadow representing a contained retroperitoneal hematoma

20. CT scan
CT scan showing blood infiltrating soft tissue in retroperitoneum

22. Any Questions?