//fpnotebook.com/
Abdominal Aortic Aneurysm
Aka: Abdominal Aortic Aneurysm, Aortic Aneurysm of Abdominal Aorta, Abdominal Aortic Ectasia
- See Also
- Abdominal Pain in Older Adults
- Arterial Atherosclerosis
- Definitions
- Abdominal Aortic Aneurysm
- Abdominal aorta diameter 3.0 cm or greater
- Abdominal Aortic Ectasia
- Abdominal aorta diameter 2.5 to 2.9 cm
- Epidemiology
- Ruptured AAA results in 11,000 deaths per year
- Responsible for 4-5% of sudden deaths in the United States
- Age Distribution
- Age under 50 years old
- Uncommon
- Age over 60 years
- Incidence 5-7% of over 60 years old
- Accounts for 75% of aneurysms
- Age 65 to 74 years old
- Tenth leading cause of death
- Men: 10% Incidence of AAA (65 to 80 years old)
- Women 1% Incidence of AAA (65 to 80 years old)
- Ages 74-84 years old
- Men: 12.5% Incidence of AAA
- Women: 5.2% Incidence of AAA
- Male:Female Ratio
- Age: 60-64 year old: 11:1
- Age: 85-90 year old: 3:1
- Ethnicity
- Black and hispanic patients are at lower risk of AAA
- Pathophysiology
- Elastin and collagen degradation in aorta wall
- Provoked by environmental stressors
- Inflammation (esp. Tobacco Abuse)
- Possible association with Chlamydia pneumoniae
- Increased wall tension (e.g. Hypertension, PVD)
- Risk Factors: AAA Development
- Similar to other Cardiovascular Risk Factors
- Tobacco Abuse (90% of patients have used Tobacco)
- First degree relative has up to a 19% risk of AAA
- Coronary Artery Disease (including prior Myocardial Infarction)
- Peripheral Arterial Disease
- Hypertension
- Age over 65 years old
- Male gender
- Risk Factors: AAA Rupture
- Female gender
- Tobacco Abuse
- Obstructive Lung Disease (FEV1 decreased)
- Hypertension
- Causes
- Associated with Atherosclerosis in only 25% of patients
- Aortic Dissection
- Mycotic Infection
- Cystic Medial Necrosis
- Ehlers-Danlos Syndrome
- Presentation
- Asymptomatic in 75% of AAA
- Abrupt onset severe pain unrelieved by position change
- Classic: Back pain or Abdominal Pain, pulsatile mass and Hypotension
- Suggestive of aneurysm enlargement or rupture
- Classic triad only present in 25-50% of cases
- Cryptic presentations are common
- Misdiagnosis as Diverticulitis, GI Bleed, Musculoskeletal cause is common (60% initial misdiagnosis rate)
- May present as referred pain to a wide range of regions (to chest, back and Scrotum)
- Microscopic Hematuria (and rarely Gross Hematuria) may lead to misdiagnosis of Renal Colic
- Aortic Rupture (20% present ruptured)
- Free Intraperitoneal Rupture (Catastrophic)
- Acute abdominal or back pain
- Flank Ecchymosis
- Cardiovascular Collapse (Hypotension)
- Sudden Death
- Sentinal Bleed (small posterolateral wall tear)
- Acute pain (constant)
- Syncope
- Pulsatile abdominal mass
- Hemodynamically stable with Tachycardia
- Needs Emergent Intervention before full rupture
- Symptoms
- Pain in Abdomen, Flank or Back
- Early satiety
- Nausea and Vomiting
- Signs: Pulsatile abdominal mass
- Technique
- Mass occurs left of midline at level of Umbilicus
- Position patient supine, knees flexed, while exhaling
- May be associated with abdominal bruit
- Efficacy of palpation for pulsatile mass >3 cm
- Test Sensitivity: 68%
- Test Specificity: 75%
- Fink (2000) Arch Intern Med 160(6):833-6 [PubMed]
- Larger AAA has higher likelihood of palpation
- AAA 3-4 cm palpable in 29% of cases
- AAA 5 cm palpable in 76% of cases
- Lederle (1999) JAMA 281:77-82 [PubMed]
- Signs: Peripheral pulses
- Check pulse
- Femoral artery
- Popliteal artery
- Interpretation
- Bounding Pulse suggests possible AAA
- Peripheral artery aneurysmal swelling
- Femoral aneurysm predicts AAA in 85% of cases
- Popliteal aneurysm predicts AAA in 62% of cases
- Signs: Miscellaneous
- Cullen's Sign
- Periumbilical Bruising
- Grey Turner's Sign
- Flank Bruising (retroperitoneal Hematoma)
- Differential Diagnosis
- See Acute Acute Abdominal Pain
- See Abdominal Pain in Older Adults
- See Acute Abdominal Pain Causes
- Acute Cholecystitis
- Perpforated peptic ulcer
- Diverticulitis
- Nephrolithiasis
- Diagnosis
- AAA is most commonly identified as an Incidental Imaging Finding
- Normal abdominal aorta diameter
- Male: 17-21 mm (infrarenal)
- Female: 15-19 mm (infrarenal)
- Abnormal Localized aortic dilatation
- Aortic diameter exceeds 1.5 times normal size
- Aortic diameter exceeds 30 mm
- Imaging: General
- See Ultrasound in Abdominal Aortic Aneurysm
- See CT in Abdominal Aortic Aneurysm
- Incidental Findings on Abdominal XRay (low Specificity)
- Calcified AAA wall visible in only 67-75%
- Soft Tissue Mass
- Loss of psoas shadow
- Loss of renal outline
- Imaging: Screening for Abdominal Aortic Aneurysm
- Indications for one-time routine screening
- USPTF Guidelines (2014, 2019)
- General screening above age 75 years is not typically recommended due to likelihood of comorbidity
- Men 65 to 75 years old
- Other AAA Risk Factor (see risk factors above, Level C recommendation)
- History of Tobacco Abuse (>100 Cigarettes lifetime, Level B recommendation)
- NNT: 294 to prevent aneurysm rupture
- NNT: 917 to prevent aneurysm rupture related mortality
- Women 65 to 75 years old
- History of Tobacco Abuse (inconclusive, consider screening)
- References
- Owens (2019) JAMA 322(22):221-18 [PubMed]
- Society for Vascular Medicine Guidelines
- Men age 60 to 85 years
- Women age 60 to 85 years with Cardiac Risk Factors
- Men and Women age >50 years and history of AAA in first degree relative
- First choice imaging study
- See Ultrasound in Abdominal Aortic Aneurysm
- Alternative for Obesity or excess intestinal gas
- Standard CT (see CT in Abdominal Aortic Aneurysm)
- Imaging: Monitoring protocol for Abdominal Aortic Aneurysm
- Ultrasound in Abdominal Aortic Aneurysm
- Aorta diameter <3.0 cm
- No surveillance (although some consider rescreening if 2.5 to 2.9 cm)
- Aorta diameter 3.0 to 3.9 cm
- Repeat Ultrasound of AAA every 2 to 3 years
- Typical rate of expansion: 1-4 mm/year
- Aorta diameter 4.0 to 5.4 cm
- Repeat Ultrasound of AAA (or CT in Abdominal Aortic Aneurysm) every 6-12 months
- Consider Surgical Consultation for AAA 5.0 cm or greater (or faster rate of expansion)
- Typical rate of expansion: 3-5 mm/year
- Aorta diameter >5.4 cm
- Surgical Consultation for elective AAA repair
- Typical rate of expansion: 7-8 mm/year (for AAA >6.0 cm)
- CT in Abdominal Aortic Aneurysm
- Indications
- Surgeon will order on referral
- See surgery indications below
- Ultrasound aorta >5.4 cm
- Change >0.5 cm in 6 months or >1 cm in 1 year
- Interpretation
- Repeat Ultrasound q3 months if aorta <5.5 cm
- Vascular surgery consult for indications below
- Admit patients with aorta >8 cm on CT Abdomen
- Imaging: Preoperative evaluation
- First Choice
- CT Angiogram
- Alternative in specific circumstances
- Abdominal Aortography
- MRI with MRA in abdominal aortic aneurysm
- Precautions
- Delayed diagnosis of AAA related symptoms has a very high mortality
- Have a low threshold for bedside Abdominal Aorta Ultrasound in age >50-60 years with Abdominal Pain or back pain
- Management: Surgical Repair
- Indications: Symptomatic Aneurysm
- Symptoms: Abdominal, back or Groin Pain with AAA
- Concurrent Hypotension suggests ruptured AAA
- Urgent surgical repair (high risk of rupture)
- Indications: Asymptomatic Aneurysm
- Aortic aneurysm diameter >5.4 cm
- AAA diameter 4-5 cm and
- Enlarging 0.5 cm in 6 months or
- Enlarging 1 cm in 1 year
- AAA diameter 7 cm with significant comorbidity
- Left Ventricular Dysfunction (CHF)
- Severe Chronic Obstructive Pulmonary Disease
- Noncorrectable symptomatic Coronary Artery Disease
- Operative Risk
- Myocardial Infarction (4.7% mortality)
- Mortality
- Elective repair: 3-5% (similar risk )
- Symptomatic Aneurysm: 26%
- Ruptured Aneurysm: 35-40%
- Sullivan (1990) J Vasc Surg 11:799-803 [PubMed]
- Operative techniques
- Open AAA repair (traditional)
- Higher 30 day mortality (4-5%) than endovascular repair (1-2%)
- However, endovascular repair benefit is absent by 1-2 years following repair
- Greenhalgh (2010) N Engl J Med 362(20): 1863-71 [PubMed]
- Endovascular repair has a higher rate of later complications
- Graft complications
- Second procedures required
- Endovascular AAA repair (Endograft)
- Accounts for 80% of intact AAA repairs and 52% of ruptured AAA repairs
- Guirguis (2019) JAMA 322(22): 2219-38 [PubMed]
- Optimal emergency stabilization procedure if infrarenal AAA (especially in elderly patients)
- Also consider if high risk with <2 years Life Expectancy
- Surveillance post procedure
- Requires CT at 1, 6 and 12 months after procedure
- Annual surveillance required after the first year
- Adverse events (10-15%)
- Lower 30 day mortality than open AAA repair
- Risk of blood leakage around endograft
- Also risk of stent graft or migration
- Similar 5 year mortality outcomes to open repair
- References
- (2005) Lancet 365:2179-86 [PubMed]
- Preoperative risk reduction
- See Preoperative Cardiovascular Evaluation
- Perioperative Beta Blocker
- Significantly decreases mortality
- Used Bisoprolol 5 mg daily >1 week pre-surgery
- Goal Heart Rate: 60 (keep systolic BP >100)
- Poldermans (1999) N Engl J Med 341:1789-94 [PubMed]
- Tobacco Cessation
- Statins for lipid lowering
- COPD optimization
- Renal Function optimization in Chronic Kidney Disease
- Prognosis
- Mortality from ruptured aneurysm: 80-90% (50% do not reach the hospital alive)
- Elective AAA Repair: 61% five year survival
- Risk of AAA rupture
- AAA <5.5 cm: 0.6-3.2% annual risk of AAA rupture
- AAA 5.5 - 6 cm: 9% annual risk of AAA rupture
- AAA 6 - 6.9 cm: 10% annual risk of AAA rupture (40% lifetime risk of rupture)
- AAA 7 cm: 33% annual risk of AAA rupture (50% lifetime risk of rupture)
- Course of small aortic aneurysms (<4 cm)
- Increase median of 2 mm per year (up to 8 mm/year)
- Biancari (2002) Am J Surg 183:53-5 [PubMed]
- Comorbid cardiopulmonary disease is common in AAA
- Prevention
- Slowing progression of AAA
- Tobacco Cessation
- Tobacco increases the incremental AAA growth rate by 0.4 mm per year
- Sweeting (2012) Br J Surg 99(5): 655-65 [PubMed]
- No strong evidence for specific antihypertensives or lipid lowering agents prior to repair
- Patient Education
- Indication for immediate evaluation in known AAA
- Pain in low back, groin, legs or buttocks
- References
- Weinstock in Herbert (2018) EM:Rap 18(6): 2-3
- Brewster (2003) J Vasc Surg 37:1106-17 [PubMed]
- Keisler (2015) Am Fam Physician 91(8): 538-43 [PubMed]
- Lederle (2003) Ann Intern Med 139:516-23 [PubMed]
- Newell (1997) Am Fam Physician 56(4):1103-8 [PubMed]
- Santilli (1997) Am Fam Physician 56(4):1081-90 [PubMed]
- Upchurch (2006) Am Fam Physician 73(7):1198-206 [PubMed]