Vascular Emergencies

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).

• CTA Findings:
  • Intimal flap (key).
  • True lumen (compressed), False lumen (larger, often thrombosed, beak sign).
• 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.

⭐ 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.

• 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.