Impending paradoxical embolism after type A aortic dissection surgery: mechanistic insight into the role of pericardial effusion and aortic geometry - a case report.

A 72-year-old woman with type A acute aortic dissection and a patent false lumen underwent emergency hemiarch replacement. On postoperative Day 13, routine contrast-enhanced computed tomography revealed an impending paradoxical embolism (IPE) and a right main pulmonary embolism. Surgical pulmonary thrombectomy and patent foramen ovale closure were performed. This case provides mechanistic insight into IPE development in the postoperative period. Early-phase hypercoagulability after acute aortic dissection, increased right atrial pressure due to pulmonary embolism, and anatomical factors such as pericardial effusion and altered aortic geometry after graft replacement may have facilitated right-to-left shunting through a previously undetected or functionally latent patent foramen ovale. The patient was discharged on postoperative Day 14 (hospitalization Day 27) and remained asymptomatic without recurrence during 5-year follow-up. This case highlights the importance of considering IPE after type A acute aortic dissection repair and supports routine postoperative imaging to detect clinically silent but life-threatening complications.