Impending paradoxical embolism. An intracardiac thrombus traversing a patent foramen ovale is a very infrequent but potentially catastrophic complication of the thromboembolic disease. It is named "impending paradoxical embolism". We report the case of a 71-year-old Caucasian male warded in ten days after a prostatectomy because of bilateral pulmonary embolism. Diagnosis was confirmed by HCT scan and the patient received anticoagulation with heparin. A transesophageal ecocardiogram disclosed a thrombus traversing foramen ovale into the left atrium. Surgical embolectomy was performed, but the patient died shortly after surgery.