Pulmonary paradoxical embolization

Paradoxical embolism can occur in a patent foramen ovale with a right to left shunt. Embolic material arising from the pelvic or leg veins or elsewhere in the venous system may bypass the pulmonary system and reach the cerebral arteries (Braun et al. 2004). 

Chest pain may be indicative of a recent myocardial infarction with complicating stroke, aortic dissection (particularly if the pain is also interscapular) or pulmonary embolism and raises the possibility of paradoxical embolism. 

PAVMs provide a direct capillary-free communication between the pulmonary and systemic circulations with three main clinical consequences (1) pulmonary arterialbloodpassing through these right-to-left shunts cannot be oxygenated which may lead to hypoxemia, (2) the absence of normal filtering capillary bed allows particulate material (air bubbles or clots) to reach directly the systemic circulation (paradoxical embolism) with potential clinical sequelae in the cerebral circulation (transient ischemic attack, stroke, brain abscess), and (3) these abnormal vessels may rupture into the bronchus (hemoptysis) or the pleural cavity (hemothorax) particularly during pregnancy. 

Telangiectasias are collections of dilated capillaries that are usually of no clinical significance (Milandre et al. 1987). They may be associated with hereditary hemorrhagic telangiectasia (the Osler-Weber-Rendu syndrome), but this is more likely to be associated with neurological complications from a pulmonary arteriovenous malformation with right-to-left shunting, such as cerebral hypoxia, brain abscess, paradoxical and septic embolism, or from an associated intracranial arteriovenous malformation or aneurysm (McDonald et al. 1998). 

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