Isolated Pulmonary Arteriovenous Fistula-Related Embolic Stroke With Large Vessel Occlusions Mimicking Artery-to-Artery Embolism: A Case Report.

Isolated pulmonary arteriovenous fistula (PAVF) leading to paradoxical embolism and stroke is rare, particularly in cases involving large vessel occlusions. Here, we present the case of a 69-year-old female with occlusion of the M2 segment of the middle cerebral artery (MCA) and stenosis of the common carotid artery (CCA) caused by PAVF, which mimicked artery-to-artery embolism. CT angiography revealed occlusion of the left M2 segment of the MCA and stenosis of the CCA. After administration of recombinant tissue plasminogen activator, both the left MCA occlusion and CCA stenosis were completely recanalized. Transthoracic contrast echocardiography revealed a significant right-to-left shunt both at rest and during the Valsalva maneuver, while chest CT angiography indicated the presence of PAVF in the lower lobe of the right lung. The anticoagulant medication rivaroxaban (15 mg) was administered to prevent the recurrence of ischemic stroke. Pulmonary arterial angiography confirmed the diagnosis of PAVF, and PAVF embolization using coils was successfully performed. At the one-year follow-up, the patient had no stroke recurrence. PAVF is a potentially fatal but treatable disease. Even in patients with large vessel occlusions, it is essential to consider PAVF as a rare underlying cause. The mechanism of PAVF-related stroke might be mistaken for artery-to-artery embolism.