Paradoxical Embolism Through Patent Foramen Ovale: A Case Report of Thrombus in Transit

BACKGROUND Paradoxical embolism through a patent foramen ovale is a rare but potentially life-threatening complication of venous thromboembolism, particularly in the setting of recent surgery. This report presents the case of a 41-year-old woman with paradoxical cerebral thromboembolism due to thrombus-in-transit via a patent foramen ovale, highlighting the importance of early recognition and intervention. CASE REPORT The patient was brought into the Emergency Department following syncope and head injury, 2 weeks following elective varicose vein surgery. Computed tomography pulmonary angiography confirmed a saddle pulmonary embolism. Magnetic resonance imaging of the brain after head injury demonstrated acute ischemic stroke in the left middle cerebral artery territory. Transthoracic echocardiography revealed a highly mobile thrombus extending from the right atrium through an interatrial defect into the left atrium and prolapsing in the left ventricle. The patient was commenced on anticoagulation, but due to the high risk of recurrent embolic events, she underwent emergent pulmonary embolectomy, atrial thrombectomy, and patent foramen ovale closure. She was discharged on apixaban for extensive deep venous thrombosis and remained well on follow-up. CONCLUSIONS This case demonstrates the importance of considering paradoxical embolism in patients presenting with both stroke and pulmonary embolism, particularly in the setting of recent surgery. Careful assessment of the patient's risk profile, combined with a collaborative discussion among all relevant specialties, plays an important role in determining the best treatment strategy for managing an entrapped thrombus within a patent foramen ovale.