Notice anything? Calcified infrarenal aortic aneurysm – posterior view

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

Abdominal Aortic Aneurysm September 25, 2009

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

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

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

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

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

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

Ultrasound

Ultrasound

Ultrasound AAA with intraluminal thrombus

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

CT with contrast Large mural thrombus Calcification of walls

CT with contrast

CT Three Dimensional Reconstruction

Angiogram

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

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

CT scan CT scan showing blood infiltrating soft tissue in retroperitoneum

Any Questions?