A rare case of impending paradoxical embolism with a complex patent foramen ovale.

A 68-year-old woman, who presented with pulmonary embolism, was diagnosed as having an impending paradoxical thromboembolism by transthoracic and transesophageal echocardiography, which revealed an entrapped thrombus in the atrial septum. The patient underwent surgery for thromboembolectomy. A patent foramen ovale (PFO) appeared as a tunnel with three openings into the left atrium; one opening located close to the antero-superior left atrial wall and two small atrial septal defects of a septum primum. A thrombus was trapped at two small atrial septal defects. This was a rare case of impending paradoxical embolism with complex morphology of PFO.