Aortic Aneurysms

On this page

Intro & Classification - Aorta's Big Bulge

  • Aortic Aneurysm: Permanent localized dilatation of aorta; diameter > 1.5x normal expected diameter.
    • Normal aorta: Thoracic ≈ 3 cm, Abdominal ≈ 2 cm.
  • Classification by Location:
    • Abdominal Aortic Aneurysm (AAA): Most common, typically infrarenal.
    • Thoracic Aortic Aneurysm (TAA).
  • Classification by Morphology:
    • Fusiform: Symmetrical, spindle-shaped (common).
    • Saccular: Asymmetrical, berry-like outpouching.
  • Wall Involvement:
    • True Aneurysm: Involves all three layers (intima, media, adventitia).
    • Pseudoaneurysm (False): Contained rupture; wall not all 3 layers.

⭐ Majority (≈90%) of AAAs are infrarenal.

Aneurysm types and aortic wall layers

Etiology & Risks - Weak Wall Woes

  • Primary: Atherosclerotic degeneration (most common).
    • Wall weakening: Elastin/collagen breakdown in media.
    • Enzymatic degradation: ↑ Matrix Metalloproteinases (MMPs).
    • Inflammation & oxidative stress contribute.
  • Key Risk Factors:
    • Advanced age (>60-65 years).
    • Male sex (M:F ≈ 4:1).
    • 📌 Smoking: Strongest modifiable risk; dose-dependent.
    • Hypertension.
    • Family history of AAA.
    • Hyperlipidemia.
  • Genetic Links:
    • Marfan (FBN1), Ehlers-Danlos Type IV (COL3A1), Loeys-Dietz (TGFBR1/2).
  • Less Common:
    • Infections (mycotic aneurysms).
    • Vasculitis (e.g., Takayasu).
    • Trauma.

⭐ Smokers have up to 5x increased risk of developing AAA and faster expansion.

Clinical Features - Silent Threats Scream

  • Often asymptomatic, discovered incidentally.
  • Thoracic Aortic Aneurysm (TAA):
    • Chest/back pain (most common).
    • Dyspnea, cough, hoarseness (recurrent laryngeal nerve).
    • Dysphagia (esophageal compression).
    • Superior Vena Cava (SVC) syndrome.
  • Abdominal Aortic Aneurysm (AAA):
    • Most are asymptomatic until rupture.
    • Pulsatile abdominal mass (often found on routine exam).
    • Abdominal or back pain (constant, gnawing; suggests expansion/impending rupture).
    • Limb ischemia (embolic phenomena).

Thoracic and abdominal aortic aneurysms

  • Rupture Triad (AAA):
    • Sudden severe pain (abdominal/back/flank).
    • Hypotension.
    • Pulsatile abdominal mass.

⭐ Most AAAs are infrarenal. Rupture into the retroperitoneum is more common than free intraperitoneal rupture, leading to a contained hematoma initially before potential free rupture and rapid exsanguination. 📌 RUPTURE = Renal colic-like pain, Unstable vitals, Pulsatile mass, Tender abdomen, Urge to defecate, Radiating pain to back/groin, Ecchymosis (Grey Turner's/Cullen's sign - late).

Diagnosis & Screening - Spotting the Swell

  • Clinical: Often asymptomatic. Pulsatile abdominal mass.
  • Imaging:
    • Ultrasound (USG): Primary for diagnosis & screening; measures diameter accurately.
    • CT Angiography (CTA): Gold standard for pre-operative planning; details anatomy, extent, vessel involvement.
    • MRA: CTA alternative (e.g., renal issues, contrast allergy).
    • AXR: Incidental finding (calcified aortic outline).
  • Screening (USPSTF):

⭐ AAA Definition: Focal aortic dilation ≥ 3.0 cm OR > 1.5 times normal diameter (normal aorta ≈ 2.0 cm).

CT scan: Normal aorta vs. abdominal aortic aneurysm

Management - Repair & Rescue

  • Indications for Repair (AAA):
    • Symptomatic (pain, embolism)
    • Diameter >5.5 cm (men), >5.0 cm (women)
    • Rapid expansion: >0.5 cm in 6 months or >1 cm/year
    • Complications: dissection, pseudoaneurysm
  • Repair Options:
    • Endovascular Aneurysm Repair (EVAR): Preferred for suitable anatomy; lower perioperative mortality.
    • Open Surgical Repair: For complex anatomy, younger patients, connective tissue disorders.
  • Ruptured AAA (Rescue):
    • Emergency surgery (EVAR or open)
    • Permissive hypotension (SBP 70-90 mmHg) until aortic control.
    • ABCDE, IV access, cross-match blood.

⭐ Post-EVAR, endoleaks are a common complication requiring surveillance and potential re-intervention. Type II endoleak (branch vessel backflow) is the most frequent.

High‑Yield Points - ⚡ Biggest Takeaways

  • Abdominal Aortic Aneurysms (AAA) are most common, typically infrarenal.
  • Atherosclerosis is the primary cause; smoking is a major risk factor.
  • Often asymptomatic; rupture triad: pain, hypotension, pulsatile mass.
  • Ultrasound for screening (men 65-75 with smoking history) & surveillance.
  • CT angiography for pre-operative planning.
  • Repair (open or EVAR) if diameter > 5.5 cm, rapidly expanding, or symptomatic.
  • Law of Laplace links size to ↑rupture risk.

Practice Questions: Aortic Aneurysms

Test your understanding with these related questions

What is the cutoff for surgery in an abdominal aortic aneurysm in asymptomatic patients?

1 of 5

Flashcards: Aortic Aneurysms

1/9

Abdominal aortic aneurysm (AAA) usually arises below the _____, but above the aortic birfucation

TAP TO REVEAL ANSWER

Abdominal aortic aneurysm (AAA) usually arises below the _____, but above the aortic birfucation

renal arteries

browseSpaceflip

Enjoying this lesson?

Get full access to all lessons, practice questions, and more.

Start Your Free Trial