Surgery Book

http://www.fpnotebook.com/

Abdominal Aortic AneurysmAka: Aortic Aneurysm of Abdominal Aorta

Advertisement

  1. Epidemiology
    1. Incidence: 5-7% of over 60 years old
    2. Age Distribution
      1. Age over 60 years accounts for 75% of aneurysms
      2. Tenth leading cause of death ages 65-74 years
    3. Male:Female Ratio
      1. Age: 60-64 year old: 11:1
      2. Age: 85-90 year old: 3:1
  2. Pathophysiology
    1. Elastin and collagen degradation in aorta wall
    2. Provoked by environmental stressors
      1. Inflammation (esp. Tobacco abuse)
      2. Possible association with Chlamydia pneumoniae
      3. Increased wall tension (e.g. Hypertension, PVD)
  3. Risk Factors: AAA Development
    1. Tobacco abuse (90% of patients have used Tobacco)
    2. First degree relative has up to a 19% risk of AAA
    3. Atherosclerosis
    4. Hypertension
    5. Chronic Obstructive Pulmonary Disease
    6. Increasing age
    7. Male gender
  4. Risk Factors: AAA Rupture
    1. Female gender
    2. Tobacco abuse
    3. Obstructive lung disease (FEV1 decreased)
    4. Hypertension
  5. Causes
    1. Associated with Atherosclerosis in only 25% of patients
    2. Aortic Dissection
    3. Mycotic Infection
    4. Cystic Medial Necrosis
    5. Ehlers-Danlos Syndrome
  6. Presentation
    1. Asymptomatic in 75% of AAA
    2. Abrupt onset severe pain unrelieved by position change
      1. Classic: Back pain, pulsatile mass and hypotension
      2. Suggestive of aneurysm enlargement or rupture
      3. Clasic triad only present in 25-50% of cases
    3. Aortic Rupture (20% present ruptured)
      1. Free Intraperitoneal Rupture (Catastrophic)
        1. Acute abdominal or back pain
        2. Flank Ecchymosis
        3. Cardiovascular Collapse (hypotension)
        4. Sudden Death
      2. Sentinal Bleed (small posterolateral wall tear)
        1. Acute pain (constant)
        2. Syncope
        3. Pulsatile abdominal mass
        4. Hemodynamically stable with tachycardia
        5. Needs Emergent Intervention before full rupture
  7. Symptoms
    1. Pain in Abdomen, Flank or Back
    2. Early satiety
    3. Nausea and Vomiting
  8. Signs: Pulsatile abdominal mass
    1. Pulsatile Abdominal Mass >30 mm
      1. AAA 3-4 cm palpable in 29% of cases
      2. AAA 3-4 cm palpable in 76% of cases
      3. Lederle (1999) JAMA 281:77
    2. Mass occurs left of midline
    3. Test Sensitivity for palpation: 30-90%
    4. Position patient supine, knees flexed, while exhaling
  9. Signs: Peripheral pulses
    1. Check pulse
      1. Femoral artery
      2. Popliteal artery
    2. Interpretation
      1. Bounding Pulse suggests possible AAA
      2. Peripheral artery aneurysmal swelling
        1. Femoral aneurysm predicts AAA in 85% of cases
        2. Popliteal aneurysm predicts AAA in 62% of cases
  10. Differential Diagnosis
    1. See Acute Acute Abdominal Pain
    2. See Abdominal Pain in Older Adults
    3. See Acute Abdominal Pain Causes
    4. Acute Cholecystitis
    5. Perpforated peptic ulcer
    6. Diverticulitis
    7. Nephrolithiasis
  11. Diagnosis
    1. Normal abdominal aorta diameter
      1. Male: 17-21 mm (infrarenal)
      2. Female: 15-19 mm (infrarenal)
    2. Abnormal Localized aortic dilatation
      1. Aortic diameter exceeds 1.5 times normal size
      2. Aortic diameter exceeds 30 mm
  12. Imaging
    1. Screening for abdominal aortic aneurysm
      1. Indications for one-time routine screening
        1. USPTF Guidelines
          1. Men 65 to 75 years of age if any history of Tobacco abuse
          2. No guidelines for women regardless of Tobacco use due to their low AAA Incidence
        2. Society for Vascular Medicine Guidelines
          1. Men age 60 to 85 years
          2. Women age 60 to 85 years with Cardiac Risk Factors
          3. Men and Women age >50 years and history of AAA in first degree relative
      2. First choice imaging study
        1. See Ultrasound in Abdominal Aortic Aneurysm
      3. Alternative for Obesity or excess intestinal gas
        1. Standard CT (see CT in Abdominal Aortic Aneurysm)
    2. Monitoring protocol for abdominal aortic aneurysm
      1. Ultrasound for aorta 3-5 cm
        1. No further testing if aorta <3.0 cm diameter
        2. Repeat ultrasound yearly if aorta 3.0 to 4.4 cm
        3. Repeat ultrasound q6 months if aorta 4.5 to 5 cm
          1. Referral to vascular surgery at this stage
        4. Repeat ultrasound q3 months if aorta 5 to 5.4 cm
      2. CT abdomen (3 mm)
        1. Indications
          1. Surgeon will order on referral
          2. See surgery indications below
          3. Ultrasound aorta >5.4 cm
          4. Change >0.5 cm in 6 months or >1 cm in 1 year
        2. Interpretation
          1. Repeat ultrasound q3 months if aorta <5.5 cm
          2. Vascular surgery consult for indications below
          3. Admit patients with aorta >8 cm on CT abdomen
    3. Preoperative evaluation
      1. First Choice
        1. CT Angiogram
      2. Alternative in specific circumstances
        1. Abdominal Aortography
        2. MRI with MRA in abdominal aortic aneurysm
    4. Incidental Findings on Abdominal XRay (low Specificity)
      1. Calcified AAA wall visible in only 67-75%
      2. Soft tissue mass
      3. Loss of psoas shadow
      4. Loss of renal outline
  13. Management: Surgical Repair
    1. Indications: Symptomatic Aneurysm
      1. Symptoms: Abdominal, back or Groin Pain with AAA
        1. Concurrent hypotension suggests ruptured AAA
      2. Urgent surgical repair (high risk of rupture)
    2. Indications: Asymptomatic Aneurysm
      1. Aortic aneurysm diameter >5.4 cm
      2. AAA diameter 4-5 cm and
        1. Enlarging 0.5 cm in 6 months or
        2. Enlarging 1 cm in 1 year
      3. AAA diameter 7 cm with significant comorbidity
        1. Left Ventricular Dysfunction (CHF)
        2. Severe Chronic Obstructive Pulmonary Disease
        3. Noncorrectable symptomatic Coronary Artery Disease
    3. Operative Risk
      1. Myocardial Infarction (4.7% mortality)
      2. Mortality
        1. Elective repair: 3-5% (similar risk )
        2. Symptomatic Aneurysm: 26%
        3. Ruptured Aneurysm: 35-40%
        4. Sullivan (1990) J Vasc Surg 11:799
    4. Operative techniques
      1. Open AAA repair (traditional)
      2. Endovascular AAA repair (Endograft)
        1. Consider if high risk with <2 years life expectancy
        2. Surveillance post procedure
          1. Requires CT at 1, 6 and 12 months after procedure
          2. Annual surveillance required after the first year
        3. Adverse events (10-15%)
          1. Lower 30 day mortality than open AAA repair
          2. Risk of blood leakage around endograft
          3. Also risk of stent graft or migration
          4. Similar 5 year mortality outcomes to open repair
        4. References
          1. (2005) Lancet 365:2179
    5. Preoperative risk reduction
      1. See Preoperative Cardiovascular Evaluation
      2. Perioperative Beta Blocker
        1. Significantly decreases mortality
        2. Used bisoprolol 5 mg daily >1 week pre-surgery
        3. Goal Heart Rate: 60 (keep systolic BP >100)
        4. Poldermans (1999) N Engl J Med 341:1789
      3. Tobacco Cessation
      4. COPD optimization
      5. Renal Function optimization in Chronic Kidney Disease
  14. Prognosis
    1. Mortality from ruptured aneurysm: 90%
    2. Elective AAA Repair: 61% five year survival
    3. Risk of AAA rupture
      1. AAA <5.5 cm: 0.6-3.2% annual risk of AAA rupture
      2. AAA 5.5 - 6 cm: 9% annual risk of AAA rupture
      3. AAA 6 - 6.9 cm: 10% annual risk of AAA rupture
      4. AAA 7 cm: 33% annual risk of AAA rupture
    4. Course of small aortic aneurysms (<4 cm)
      1. Increase median of 2 mm per year (up to 8 mm/year)
      2. Biancari (2002) Am J Surg 183:53
    5. Comorbid cardiopulmonary disease is common in AAA
  15. Patient Education
    1. Indication for immediate evaluation in known AAA
      1. Pain in low back, groin, legs or buttocks
  16. References
    1. Brewster (2003) J Vasc Surg 37:1106
    2. Lederle (2003) Ann Intern Med 139:516
    3. Newell (1997) Am Fam Physician 56(4):1103
    4. Santilli (1997) Am Fam Physician 56(4):1081
    5. Upchurch (2006) Am Fam Physician 73(7):1198

Aortic Aneurysm, Abdominal (C0162871)

Definition (MSH)An abnormal balloon- or sac-like dilatation in the wall of the ABDOMINAL AORTA which gives rise to the visceral, the parietal, and the terminal (iliac) branches below the aortic hiatus at the diaphragm.
ConceptsDisease or Syndrome (T047)
MSHD017544
EnglishAAA, AAA - Abdominal aortic aneurysm, AAA1, Abdominal Aortic Aneurysm, Abdominal Aortic Aneurysms
Spanishaneurisma de aorta abdominal
Parent ConceptsAortic Aneurysm (C0003486), Abdominal aorta finding (C0425668), Vascular disease of abdomen (C1290390), Aneurysm of descending aorta (C0856750), Duplicate concept (C1274013)
SourcesCOSTAR, DXP, MSH, MTH, NCI, NDFRT, OMIM, SCTSPA, SNOMEDCT
Derived from the NIH UMLS (Unified Medical Language System)



Navigation Tree