Abdominal Aortic Aneurysm
Signs and Symptoms
75% are asymptomatic at diagnosis Asymptomatic AAA generally discovered during incidental radiologic or surgical procedure. CLASSIC TRIAD SIGN Hypotension, pulsatile abdominal mass, and abdominal pain or back pain. Abdominal discomfort, back pain, pulsation of abdomen or flank pain. Less frequently: complain of pain in the legs, chest, or groin area. May report anorexia N/V, dyspnea. In a patient with a hx of aneurysm or pulsatile mass, abdominal pain must be considered a rapidly expanding or ruptured aneurysm and must be treated accordingly.
Definition
An abdominal aortic aneurysm (AAA) is a progressive, permanent, localized dilation of the abdominal aorta with aortic diameter of 3.0 cm or more, or a 50% increase in diameter compared with the adjacent normal segment. Aneurysms are described by their shape, which helps determine a true aneurysm. A true aneurysm involves all 3 layers of the aorta. Treatment recommended when AAA grows to a diameter >5.5 cm.
Diagnosis and differential diagnosis
Differential diagnosis for AAA include conditions a/w abdominal pain or back pain. Nephrolithiasis; pancreatitis; bowel obstruction; cholithiasis; diverticulitis Myocardial Infarction; esophageal rupture; perforated gastric ulcer GI bleed; appendicitis; pyelonephritis; ischemic bowel; back strain; arthritis; neoplasm.
Etiology and Risk Factors
Major risk factors include: advancing age (>65), male gender, family history of AAA, and cigarette smoking. Other factors include atherosclerotic vascular disease, HTN, HLD, and other vascular aneurysms. Factors associated with AAA development: tobacco use, hypercholesterolemia, HTN, male gender, family history. Factors associated with expansion: advanced age, severe cardiac disease, previous stroke, tobacco use, cardiac or renal transplant.
Treatment and Management
Managed with traditional open surgical repair, minimally invasive abdominal EVAR or continuous surveillance. Goal→ prevent aneurysm all rupture while minimizing surgical risk. AAA size is the best predictor of rupture. >50% chance of rupture with diameter 7.0 cm or greater. Unless aneurysm exceeds 5.5cm, there is no long-term survival advantage of early surgery over serial US surveillance every 6 months. Refer to vascular surgeon when AAA is 4.0 cm or larger. US to follow growth every 6 months then every 6-12 months for AAA measuring 4.0-5.4 cm. Address risk factors such as smoking, HTN, DM management. Encourage physical activity but avoid heavy lifting or exercises that involve straining Educate on symptoms to report: abdominal, back pain, flank pain. Abdominal pain characterized as: deep, boring, tearing. Low back pain: dull, radiating to the legs. Flank pain: radiate to the groin and a/w hematuria. First degree relative of someone with AAA should have US at 50 year.
Clinical findings/ Test
Palpation of the abdomen for AAA is a recommended EBP maneuver in periodic health exam of older men. Patient positioned supine with knees flexed to relax the abdominal wall. AAA suspected when the aorta is at least 3.0cm in maximum diameter. The sensitivity of abdominal palpation for AAA increased with the diameter (bigger ones easier to feel) 5.0cm or greater. Sensitivity increases when abdominal girth is less than 100cm (40 inch waist) If on examination, one finds a pulsatile mass in the groin or popliteal fossa, this raises the suspicion for a AA because multiple aneurysms often coexist. AHA and ACC recommend that men over 60 years who are either a sibling or offspring of patients with AAA should undergo a physical examination and ultrasound screening for detection of aortic aneurysm. Ultrasonography→ Provides accurate measurement of initial size and can be used for serial follow-up evaluation. Computed Tomography Angiography (CTA): three-dimensional imaging is preferred before aortic aneurysm repair. CTA, MRI, MRA used for preoperative imaging.
