Paradoxical embolism, stroke

Thrombophilias and other causes of hypercoagulability are rare causes of stroke (Matijevic and Wu 2006). Antithrombin III deficiency, protein C deficiency, activated protein C resistance owing to factor V Leiden mutation, protein S deficiency and plasminogen abnormality or deficiency can all cause peripheral and intracranial venous thrombosis. Thrombosis is usually recurrent and there is often a family history. Thrombophilia may cause arterial thrombosis, although the alternative diagnosis of paradoxical embolism should always be considered in patients with these disorders. It should be noted that deficiencies in any one of the factors associated with thrombophilia may be an incidental finding and cannot necessarily be assumed to be the cause of stroke. 

Mechanisms include thrombocytosis, hypercoagulability, immobility and paradoxical embolism, vasculitis and dehydration. The bowel disease is not necessarily severe at the time of the stroke. Coeliac disease can also be complicated by a cerebral vasculitis but this often presents with an encephalopathy rather than a stroke (Mumford et al. 1996). 

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. 

Complications tend to occur when pacing catheters are left in place for longer then 72h (35). Infections can track down the catheter and care should be taken whenever the catheter or vascular sheath is manipulated. The catheter should be left within a sterile sleeve that allows for subsequent advancement and withdrawal. Acute thrombosis of the vein can occur, leading to extremity engorgment and to thromboembolic events. Routine anticoagulation, however, is not considered to be necessary unless there is a septal defect that could allow a venous thrombus to cause a stroke (paradoxical embolism). 

Fatal stroke due to paradoxical fat embolism. Cerebrovascular Diseases 6 313-314... 

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