Echocardiographic features of PFOs and paradoxical embolism: a complicated puzzle.

Patent foramen ovale (PFO) is a residual, oblique, slit or tunnel like communication in the atrial septum that persists into adulthood. It is usually an incidental finding with no clinical repercussions. Nevertheless, recent evidence supports the association between the presence of a PFO and a number of clinical conditions, most notably cryptogenic stroke (CS).