Sandbox:Hira Rehman
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Hira Rehman, MD[2]
Synonyms and keywords:
First statement
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Overview A paradoxical embolism refers to a phenomenon of dislodging a clot from venous vasculature which traverses through intracardiac or intrapulmonary shunt into systemic circulation. If dislodged into brain, it could cause ischemic stroke with neurological manifestations depending on the site of blockade of intracranial arteries.
Pathophysiology Paradoxical embolism involves passage of a venous clot (thrombus) from a vein to an artery. When clots in veins break off (embolize), they travel first to the right side of the heart and, normally, then to the lungs where they lodge, causing pulmonary embolism. On the other hand, when there is a hole in the wall between the two upper chambers of the heart (an atrial septal defect), a clot can cross from the right to the left side of the heart, then pass into the arteries as a paradoxical embolism. Once in the arterial circulation, a clot can travel to the brain, block a vessel there, and cause a stroke (cerebrovascular accident). The clot can lodge in the cerebral circulation, the coronary circulation, the mesenteric circulation, or in the circulation to a limb.
Diagnosis Three conditions are required to meet clinical diagnosis:
1) Venous source of embolism
2) Presence of intracardiac shunt or pulmonary fistula
3) Arterial Embolism
Echocardiography A bubble study can be useful in establishing the presence of right-to-left shunting in the evaluation of the patient with suspected paradoxical embolism. It should be noted that bidirectional shunting can also be associated with paradoxical embolism.
Treatment Treatment of paradoxical embolization involves either:
Closure of the defect in the heart( closure of an atrial septal defect (ASD), ventricular septal defect (VSD), or patent foramen ovale (PFO)) Anticoagulation Placement of a inferior vena cava (IVC) filter Discontinuation of birth control pills Smoking cessation