Pulmonary Vascular Diseases

Pulmonary Vascular Diseases

Pulmonary Vascular Diseases

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Pulmonary Embolism - Clot Shot Chaos

  • Pathophysiology: Virchow's triad (stasis, hypercoagulability, endothelial injury) → DVT → PE.
  • Risk Factors: Immobility, surgery, malignancy, OCPs, pregnancy, thrombophilia.
  • Clinical: Sudden dyspnea, pleuritic chest pain. D-dimer: Rules out PE if low pre-test probability (Wells/Geneva).
  • Imaging Modalities:
    • CT Pulmonary Angiography (CTPA) - Gold Standard:
      • Direct: Filling defects (central, mural, complete), polo mint, railway track. CTPA showing saddle pulmonary embolism
      • Indirect: RV strain (RV/LV >1), septal bowing.
    • V/Q Scan:
      • Indications: CTPA contraindicated (contrast allergy, renal failure, pregnancy).
      • Finding: Mismatched perfusion defects (high probability).
    • Chest X-ray (CXR):
      • Often normal. Classic (rare) signs: 📌 WHALES (Westermark, Hampton's, Atelectasis, Low-grade fever, Effusion, Normal).
      • Key signs: Westermark (oligemia), Hampton's hump (wedge opacity). Chest X-ray: PE Signs (Hampton's, Westermark, Fleischner)

⭐ A normal chest X-ray is common in patients with pulmonary embolism, but specific signs like Westermark's sign or Hampton's hump, though infrequent, are highly suggestive.

Pulmonary Hypertension - Pressure Cooker Pipes

Defined by mean pulmonary arterial pressure (mPAP) > 20 mmHg at rest. Echocardiography is the initial screening tool.

  • WHO Classification of PH (Groups 1-5):

    GroupTypeKey Examples/Etiologies
    1Pulmonary Arterial Hypertension (PAH)IPAH, CTD-associated
    2PH due to Left Heart DiseaseLV dysfunction, Valvular disease
    3PH due to Lung Diseases/HypoxiaCOPD, ILD, OSA
    4Chronic Thromboembolic PH (CTEPH)Chronic thromboemboli
    5PH with Unclear/Multifactorial MechanismsSarcoidosis, Hematologic disorders
  • Imaging Findings:

    • CXR: Enlarged central pulmonary arteries, peripheral 'pruning' of vessels, right ventricular enlargement/cardiomegaly, prominent right atrium.

    • CT:

      • Main Pulmonary Artery (MPA) diameter > 29 mm or MPA diameter > ascending aorta diameter.
      • Right Ventricular (RV) hypertrophy (wall thickness > 4mm).
      • RV dilatation (RV/LV diameter ratio > 1).
      • Interventricular septum flattening/bowing into LV.
      • Mosaic attenuation pattern in lung parenchyma. Axial CT chest: Pulmonary hypertension

      ⭐ On CT, a main pulmonary artery diameter greater than 29 mm or exceeding the diameter of the adjacent ascending aorta are key indicators of pulmonary hypertension.

Other Vascular Lesions - Twisted Tubes Terrors

  • Pulmonary Artery Aneurysms & Pseudoaneurysms
    • Aneurysm: true (all layers); Pseudo: contained rupture.
    • Causes: Behçet's, infections (Rasmussen’s-TB), iatrogenic, congenital, trauma.
    • Imaging: CTA key. CT angiogram of pulmonary arteriovenous malformation
  • Pulmonary Arteriovenous Malformations (PAVMs)
    • Abnormal PA-PV connection (direct shunt).
    • Mostly congenital; strong HHT/Osler-Weber-Rendu link. 📌 HHT: Telangiectasias, AVMs, Epistaxis, Family Hx.
    • Complications: Paradoxical emboli (stroke, brain abscess), hypoxemia.
    • Imaging:
      • CXR: Round/oval opacity, feeding artery & draining vein.
      • CT: Enhancing nidus, feeding artery, draining vein.

    ⭐ The majority of pulmonary arteriovenous malformations (PAVMs) are congenital and are found in approximately 15-30% of patients with Hereditary Hemorrhagic Telangiectasia (HHT).

  • Pulmonary Vasculitides (Radiological Focus)
    • Large Vessel (Takayasu): PA stenosis/occlusion, aneurysms.
    • ANCA-assoc. Small Vessel:
      • GPA (Wegener's): Nodules, cavitations, DAH.
      • MPA: DAH, GGOs.

High‑Yield Points - ⚡ Biggest Takeaways

  • CTPA is gold standard for Pulmonary Embolism (PE) diagnosis.
  • PE X-ray signs: Westermark sign, Hampton's hump, Palla's sign.
  • Pulmonary Arterial Hypertension (PAH): Main PA diameter >29 mm, RV hypertrophy.
  • Pulmonary Venous Hypertension: Cephalization, Kerley B lines, bat-wing edema.
  • Pulmonary AVMs: Congenital nodules with feeding artery & draining vein.
  • CTEPH: Mosaic attenuation, webs/bands, post-PE complication_._

Practice Questions: Pulmonary Vascular Diseases

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Which of the following is not associated with pulmonary arterial hypertension?

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Flashcards: Pulmonary Vascular Diseases

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Pulmonary _____ is seen on x-ray in VSD due to large volume of shunted blood passing through the lungs

TAP TO REVEAL ANSWER

Pulmonary _____ is seen on x-ray in VSD due to large volume of shunted blood passing through the lungs

plethora

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