CRYPTOGENIC STROKE

When clots develop in the venous system and travel from their site of origin to the right side of the heart, they normally are filtered and trapped by the lungs, where they eventually dissolve. However, if a PFO is present, a clot may pass from the right side to the left side of the heart without being filtered by the lungs. The clot may then travel through the arteries that supply oxygenated blood to the brain and become lodged there, causing a stroke. While the lungs may tolerate small clots without clinical consequence, the brain is acutely susceptible to even the smallest clot.

Acute Infarct of Posterior Cerebral Artery
The PFO in Cryptogenic Stroke Study (PICSS) from Columbia University in New York was published in the June 4, 2002 issue of Circulation. The published background section of this study states that, “Approximately 40% of cerebral infarctions cannot be classified as strokes of determined cause despite a complete diagnostic work-up and are labeled as 'cryptogenic strokes.'" According to the Stroke Council of the American Heart Association, about 500,000 strokes each year worldwide may be attributable to the presence of a PFO.

Acute Infarct of Posterior Cerebral Artery