Abstract
Two cases of thrombotic embolus arrested in a patent foramen ovale are described. Both were middle-aged men who also had pulmonary emboli. Reports of 52 similar cases have been published. As well as venous thrombosis and an abnormal vascular communication, reversal of the normal left-to-right pressure gradient is required, and the usual cause of this is antecedent pulmonary embolism. The communication is usually a patent foramen ovale, but ventricular septal defects and the ductus arteriosus have been involved. Clinical diagnosis is rare.