Postoperative Stroke Through a Patent Foramen Ovale in a Patient With Lung Cancer: A Case Report.

Cerebral infarction is a rare but serious complication after pulmonary resection for lung cancer. A 78-year-old man with hypertension and diabetes underwent video-assisted thoracoscopic right middle lobectomy for stage IA2 adenocarcinoma. On postoperative day 1, he developed acute right hemiparesis and motor aphasia. Diffusion-weighted magnetic resonance imaging revealed acute infarction in the left frontal lobe. Cerebral angiography showed no steno-occlusive lesions in the major cerebral arteries but demonstrated distal peripheral artery occlusions. Evaluation, including Holter monitoring, chest computed tomography, and venous ultrasound, identified no atrial fibrillation or other common embolic sources, but transthoracic echocardiography with an agitated-saline test confirmed a patent foramen ovale (PFO), suggesting paradoxical brain embolism (PBE) as the likely etiology. Treatment was initiated with aspirin on postoperative day 2, switched to apixaban after PFO confirmation. The patient was transferred to a rehabilitation facility on postoperative day 23, with marked improvement in paresis and aphasia, returning to near-baseline activities of daily living. Perioperative strokes are often observed in patients with multiple underlying risk factors. In pulmonary resection, pulmonary vein stump thrombosis has been proposed as a causative mechanism, although PBE through PFO warrants consideration as an important alternative etiology because lung resection creates ideal conditions for PBE by combining increased venous thrombosis risk with elevated right heart pressures due to loss of the pulmonary vascular bed.