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Pulmonary AVM shunt physiology — SCE Respiratory MCQ

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HardPulmonary Vascular DiseasePulmonary AVM shunt physiologySCE Respiratory

A 31-year-old man with hereditary haemorrhagic telangiectasia has migraines and a previous brain abscess. Contrast echocardiography shows late bubble appearance in the left heart. CT confirms multiple pulmonary AVMs. What is the most likely underlying cause of his neurological complications?

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Correct answer: B — Right-to-left shunting bypassing the pulmonary capillary filter

Pulmonary AVMs create right-to-left shunts that bypass the pulmonary capillary filter, allowing paradoxical emboli and septic emboli causing stroke or brain abscess. Pulmonary venous hypertension and airway disease do not explain late bubbles and neurological septic emboli. Pleural lymphatic obstruction would cause effusion rather than brain abscess.

Reference: BTS Clinical Statement on Pulmonary Arteriovenous Malformations