Abdominal aortic aneurysm resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:

Synonyms and keywords:

Overview

Abdominal aortic aneurysm (AAAs) are defined as abnormal dilation of abdominal aorta, mostly in infrarenal part of aorta with extension to iliac arteries, up to more than 3 cm in the greatest diameter or dilatation of more than 50% of its diameter. Aneurysm is related to regional weakening of vessels wall structure. Although AAAs are more common in men than women, women with AAAs have worse prognosis than men. The predisposing factors include male gender, age >75 years, prior vascular disease, hypertension, smoking, family history of cardiovascular disease, hypercholesterolemia. The incidence of AAAs has continued to rise, of which they remain the leading cause of death in USA. Most AAAs are usually asymptomatic and detected accidentally. Unruptured aneurysms may present mild abdominal or back pain with pulsatile mass while ruptured aneurysms cause severe abdominal or back pain, hypotension and shock and they are associated with high mortality. AAAs are attributed to primary and secondary aneurysm. Primary aneurysms relate to defects in vessel wall (i.e. fibrillin deficiency or collagen III deficiency). Secondary aneurysms relate to turnover and pathological vessel wall remodelling. Imaging is vital for detection of AAAs. Abdominal X-ray and ultrasound are performed to detect AAAs. However, ultrasound is simple, safe and inexpensive with sensitivity of 95% and specificity close to 100%. CT angiography is another imaging option which is the gold standard in evaluation of aortic size and extension of aneurysm, though it has high radiation doses.

Causes

Life Threatening Causes

Acute ruptured AAAs are surgical emergencies and if left untreated, it has a mortality rate approaching 100%.

Common Causes

Atherosclerosis is the most common cause ^[1]
Vasculitis
- Takayasu arteritis
Marfan syndrome
Ehlers-Danlos syndrome
Mycotic aneurysm
Traumatic pseudoaneurysm

Screening

Screening of abdominal aortic aneurysm is identifying people who are at risk of AAAs:

All men aged 66 and over who have not already been screened and have risk factors.
Consider an aortic ultrasound for women aged 70 and over who already have risk factors.
Think about the possibility of ruptured AAA in people with new abdominal and/or back pain, cardiovascular collapse, or loss of consciousness.

Treatment

Ruptured Abdominal Aortic Aneurysms (rAAA)

^[2]

Patient with suspected rAAA

Hemodynamically stable (systolic BP > 80mm Hg)

Hemodynamically unsatable (systolic BP < 80mm Hg)

Emergent CT angiography in ER

Operating room:
Ready for Endovascular and Open Surgical Repair

Hemodynamic

Stable

Unstable

❑ General anesthesia
❑ Femoral artery cutdown
❑ Aortic balloon occlusion

❑ Percutaneous femoral access
❑ Aortic balloon occlusion

Evaluate aortic morphology

Suitable aortic neck

Unsuitable aortic neck

Endovascular Aneurysm Repair (EVAR)

❑ Aortic occlusion balloon
❑ Laparotomy
❑ Open surgical repair

Asymptomatic Abdominal Aortic Aneurysms

^[3]

Uruptured AAAs

Evaluate the dilatation

< 4.5 cm

4.5-5 cm

5-5.5 cm

> 5.5 cm

❑ Follow up
❑ Ultrasonography every 6 months

❑ Follow up
❑ Ultrasonography every 3 months

Surgery:
Open or Endovascular Aneurysm Repair (EVAR) if:
❑ Female patient
❑ Positive family history
❑ Rapid growth
❑ Positive pet scan
❑ High serum markers (such as MMP-9)