Vascular Emergencies

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Aortic Dissection & AAA Rupture - Aorta's Acute Agonies

Aortic Dissection: Acute tear in aortic intima, blood enters media.

  • Classifications:
    • Stanford: 📌 A = Ascending aorta involved (surgical emergency); B = Beyond (descending only, medical Rx typically).

    • DeBakey: I (Ascending + Arch/Descending), II (Ascending only), III (Descending only). DeBakey Classification of Aortic Dissection

  • CTA Findings:
    • Intimal flap (key).
    • True lumen (compressed), False lumen (larger, often thrombosed, beak sign). Aortic dissection diagram
  • Complications: Malperfusion, rupture.

Ruptured Abdominal Aortic Aneurysm (AAA):

  • Aorta diameter > 3 cm; rupture risk ↑ if > 5.5 cm.
  • CTA Signs of Rupture:
    • Retroperitoneal hematoma (most common).
    • Active contrast extravasation.
    • Draped aorta sign. Ruptured AAA with retroperitoneal hematoma and extravasation

⭐ Sudden "tearing" chest/back pain is classic for aortic dissection.

Pulmonary Embolism - Clots' Lung Lodge

  • Risk stratification via Wells or Geneva scores guides investigation.

  • Diagnostic Algorithm:

  • CTPA (Gold Standard):

    • Direct signs: Central filling defects (partial/complete occlusion), "polo mint" sign (cross-section), railway track sign (longitudinal).
    • Saddle embolus: Large clot at main pulmonary artery bifurcation.
  • Ancillary Signs (CXR/CT):

    • Westermark sign: Regional oligemia distal to embolus.
    • Hampton's hump: Peripheral wedge-shaped opacity (infarct).
    • Right heart strain: RV dilatation (RV/LV diameter ratio >1.0 on axial CT), septal bowing.
  • V/Q Scan: For CTPA contraindications (e.g., renal failure, contrast allergy); identifies ventilation-perfusion mismatches.

⭐ The "polo mint" sign on CTPA, representing a central filling defect surrounded by contrast, is a direct sign of acute PE.

Acute Stroke Imaging - Brain's Blood Blockade

  • Non-Contrast CT (NCCT): First-line to exclude hemorrhage.

    • Early ischemic signs (<6 hrs): Hyperdense MCA sign (clot), loss of grey-white differentiation, insular ribbon sign (obscuration), sulcal effacement. NCCT Head: Hyperdense MCA sign, early ischemic changes
  • CT Angiography (CTA): Identifies vessel occlusion site (e.g., LVO).

  • CT Perfusion (CTP): Differentiates core (irreversible damage: ↓CBF, ↓CBV) from penumbra (salvageable tissue: ↓CBF, normal/↑CBV, ↑MTT/TTP).

  • MRI Brain: Gold standard for early infarct.

    • DWI: Hyperintense (restricted diffusion) within minutes. ADC map: Corresponding hypointensity.
  • ASPECTS (Alberta Stroke Program Early CT Score): Quantifies early MCA ischemic changes on NCCT. Score 0-10 (10=normal). Lower score = worse outcome.

    • 📌 Areas: Caudate, Lentiform nucleus, Internal capsule, Insular cortex, plus M1-M6 (MCA cortical regions).

⭐ DWI is the most sensitive sequence for detecting acute ischemic stroke within minutes of onset.

Mesenteric & Limb Ischemia - Gut & Limb Peril

  • Mesenteric Ischemia: Critical reduction in intestinal blood flow.

    • Arterial (AMI): SMA most common. Embolic (AFib) or thrombotic.

      • CTA (Gold Standard): SMA/IMA occlusion; bowel wall changes (thickening/hyperemia → thin/↓enhancement); pneumatosis intestinalis; portal venous gas (PVG).
    • Venous (MVT): SMV common. Hypercoagulable states, portal HTN.

      • CTA: SMV/portal vein filling defect, bowel wall thickening, mesenteric congestion. ⭐ > Pneumatosis intestinalis & portal venous gas on CTA: ominous signs of advanced mesenteric ischemia, suggest infarction.
  • Acute Limb Ischemia (ALI): Sudden ↓limb perfusion; threatens viability. 📌 6 P's (Pain, Pallor, Pulselessness, Paresthesia, Paralysis, Poikilothermia).

    • Doppler US: Initial; confirms ↓/absent flow, locates occlusion.
    • CTA: Definitive; shows occlusion/stenosis (level/extent), collaterals. "Meniscus sign" or abrupt cut-off.

High‑Yield Points - ⚡ Biggest Takeaways

  • Aortic Dissection: CTA gold standard; Stanford A (ascending) surgical, Type B medical.
  • Pulmonary Embolism: CTPA diagnostic choice; shows pulmonary artery filling defects.
  • DVT: Compression US (CUS) reveals non-compressible deep veins.
  • Acute Mesenteric Ischemia: CTA crucial; shows bowel wall thickening, pneumatosis.
  • Ischemic Stroke: Initial NCCT head excludes hemorrhage; MRI (DWI) for acute infarct.
  • SAH: NCCT head detects blood; CTA identifies aneurysm.
  • Traumatic Vascular Injury: CTA shows active extravasation, pseudoaneurysm, dissection.

Practice Questions: Vascular Emergencies

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Which of the following is not a branch of the inferior mesenteric artery?

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Flashcards: Vascular Emergencies

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What is the best modality to identify cocaine packets in a body packer?_____

CT imaging

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