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Images in Neurology
July 2004

Transient Ischemic Attack and Patent Foramen Ovale: Evidence of Paradoxical Embolism

Arch Neurol. 2004;61(7):1133. doi:10.1001/archneur.61.7.1133

Strokes of undetermined etiology, or cryptogenic strokes, account for as many as 40% of cerebral infarcts.1 Lechat et al2 have shown that the presence of a patent foramen ovale (PFO) is associated with cryptogenic stroke. The PFO is a remnant of fetal circulation. In utero, it functions as a conduit for oxygenated blood from the right to the left atrium, bypassing the lungs. At birth, the path of circulation changes, and the foramen ovale is sealed in the first year of life. However, in a significant percentage of the population, a persistent connection is seen. The presumed mechanism of cerebral ischemia is right-to-left shunting through the PFO. This abnormal communication between the left and right atria allows emboli from the venous system to pass through and cause arterial embolization. Most reports of PFO-associated strokes do not demonstrate a venous source of embolism in combination with an intracardiac thrombus. We describe herein a patient with cerebrovascular symptoms in whom we have documented both a venous source of embolism and a thrombus straddling a PFO.

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