Paradoxical embolism

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A paradoxical embolism is a kind of stroke or other form of arterial thrombosis caused by embolism of a thrombus (blood clot) of venous origin through a lateral opening in the heart, typically an atrial septal defect.

Paradoxical embolism: Passage of a 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). Also called crossed embolism.