Abdominal aortic aneurysm resident survival guide

Abdominal aortic aneurysm Resident Survival Guide Microchapters
Overview
Causes
Screening
Treatment
Ruptured Aneurysms
Asymptomatic Aneurysms
Do's
Don'ts

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Seyed Arash Javadmoosavi, MD[2]

Synonyms and keywords: Approach to abdominal aortic aneurysm; Abdominal aortic aneurysm workup; Abdominal aortic aneurysm screening algorithm

Overview

Abdominal aortic aneurysm (AAAs) are defined as abnormal dilation of abdominal aorta, mostly in the 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. Aneurysms are related to regional weakening of the 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 and hypercholesterolemia. The incidence of AAAs has continued to rise, of which they remain the leading cause of death in USA. The majority of AAA cases 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 remodeling. Imaging is vital for detection of AAAs. Abdominal X-ray and ultrasound are performed to detect AAAs.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
• 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. The method of screening for AAA is abdominal ultrasonography and must be performed in the following individuals:

• All men aged 66 and over who have not already been screened and have risk factors.
• Men aged 55 years or older with a family history of AAA.
• Women aged 70 and over who already have risk factors.
• People with new abdominal and/or back pain accompanied by cardiovascular collapse, or loss of consciousness (due to the possibility of AAA rupture).

The table below provides the indication of AAA screening based on various society guidelines:

SVS	ACPM/CSVS	ESVS	USPSTF	NHS	ACC/AHA
Men >55 years with a family history All men >65 y Women >65 years who have smoked or have a family history	Men 65-75 years who ever smoked All men 65-75 years old Women Do not screen No recommendation for>65 years May be beneficial when other risk factors are present (smoking, cerebrovascular disease, family history)	Men 65 years <65 years if at increased risk (smoke, cardiovascular disease) or family history Women Do not screen Need more research in older female smokers	Men 65 to 75 years who ever smoked Women 65 to 75 years who ever smoked	Men 65 years Women 70 and over who already have risk factors	Men 65-75 years who ever smoked 60 years with family history Women Do not screen

Abbreviations: SVS:Society for Vascular Surgery; ACPM:American College of Preventive Medicine; CSVS:Canadian Society for Vascular Surgery; ESVS:European Society for Vascular Surgery; USPTF:U.S. Preventive Task Force; NHS:National Health Society; AHA:American Heart Association; ACC:American College of Cardiology

Treatment

Ruptured Abdominal Aortic Aneurysms (rAAA)

Patient with suspected rAAA

Hemodynamically stable (systolic BP > 80mm Hg)

Hemodynamically unstable (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

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)

❑ Follow up ❑ Ultrasonography every 3 months

Surgery: Open or Endovascular Aneurysm Repair (EVAR)

Do's

• Control the known risk factors by administering lipid lowering agents ,antihypertensive therapy and platelet aggregation inhibitors.
• Administer β-blockers in cases that may benefit more.
• ACE-inhibitors prescription may reduce the risk of rupture in asymptomatic patients with AAAs.
• Blood pressure of patient with AAAs should be precisely controlled to avoid rupture and expansion.
• Encourage patients to stay physically active.
• Eat a healthful diet that is low in saturated fat and rich in whole grains, fruits, and vegetables.

Don'ts

• Instruct the patients to stop smoking.
• Patients with family history of AAA should stop smoking with the aid of behavior modification, nicotine replacement, or bupropion therapy.