Definition: An AAA is defined as abdominal aorta with a maximal diameter >3.0 cm. A small AAA has a diameter <4.0 cm. A medium AAA has a diameter of between 4.0 and 5.5 cm. A large AAA has a diameter ≥5.5 cm. And Very large AAA has a diameter ≥6.0 cm
Diagnosis
-H&P. Look for a pulsatile mass, family history of AAA.
–Risk Factors for AAA.
Ultrasound: One-time screening U/S per USPSTF recommendations. Diagnostic (not screening) U/S in any patient with symptoms and clinical suspicion.
Treatment
–Risk factor modification: Smoking cessation, statins to achieve an LDL-C <70 mg/dL
–BP Control: Beta-blockers, ACEI, ARBs.
–Surgical repair, when indicated. Indications for surgery.
–Screen for CAD, PAD, and aneurysms elsewhere, especially popliteal because 25% of patients with an AAA will also have a TAA and vice versa.
–Consider pan-aortic imaging to exclude a concurrent TAA.
–Referral to vascular surgery.
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F/u for AAA:
-q3y for small.
-q6-12mo for medium.
-TAA = Thoracic aortic aneurysm.
“Roxithromycin (a macrolide antibiotic not available in the United States) and doxycycline have weak evidence for inhibiting AAA growth, because secondary infection in the aortic wall, likely from Chlamydophila pneumoniae, may promote AAA progression”
Open or endovascular aneurysm repair are equally effective. Open has more complications early on than endovascular, but endovascular has more graft rejection and complication issues later on than open. At 2-3 years, the complications are about the same and the advantage of endovascular aneurysm repair disappear.
Explanation
-The 2009 guidelines from the Society for Vascular Surgery recommend observation for asymptomatic AAA <5.5 cm in diameter. Why? Because for asymptomatic patients, randomized trials comparing observation with open or endovascular AAA repair have found that the risk of AAA rupture generally does not exceed the risk associated with elective AAA repair until aneurysm diameter exceeds 5.5 cm.
-For asymptomatic infrarenal AAA <5.5 cm, conservative management (watchful waiting) rather than elective AAA repair is recommended. The risk of aneurysm rupture does not exceed the risk of repair until the aneurysm diameter reaches 5.5 cm.
-Will refer for elective repair of asymptomatic AAA <5.5 cm if 1) Rapidly expanding (>0.5 cm in six months or >1 cm per year) infrarenal AAA. 2) Patients have an associated arterial disease such as coexisting iliac, femoral, or popliteal artery aneurysms, or symptomatic peripheral artery disease. 3) For the same diameter AAA, the risk for AAA rupture is higher for women than for men. Elective repair of asymptomatic AAA >5 cm may be appropriate; however, the risk of death from elective repair is also increased in women. A lower threshold for repair is recommended for women who have a low risk for perioperative morbidity and mortality.
-For patients with <4cm AAA, have yearly follow-up ultrasounds to follow its progression.
-For medium-sized aneurysms (4 to 5.5 cm in diameter), Ultrasound or CT every 6 to 12 months.
-Never wait until the patient becomes symptomatic to do the surgery!
References:
Cardiol Rev. 2016 Mar-Apr;24(2):88-93. Risk factors for abdominal aortic aneurysms: a 7-year prospective study. https://www.ncbi.nlm.nih.gov/pubmed/19364978
Am Fam Physician. 2015 Apr 15;91(8):538-543. http://www.aafp.org/afp/2015/0415/p538.html
http://www.uptodate.com/contents/management-of-asymptomatic-abdominal-aortic-aneurysm