A shortcut in the heart. Patent foramen ovale causes no problems in most people. But it may explain some mysterious strokes.
D006344:Heart Septal Defects, Atrial / Q000150:complications* / Q000601:surgery; D006801:Humans; D012307:Risk Factors; D020521:Stroke / Q000209:etiology* / Q000517:prevention & control*; D014481:United States