2 CASE DESCRIPTION
A 15-year-old boy presented with recurrent onset dizziness, blurred vision in both eyes and bilateral limbs weakness for 2 years. During the attack, he could not stand and fainted onto the ground, then recovered spontaneously about 5min later, no nausea, no vomiting, no tinnitus, no hearing loss, no convulsion, and no a history of epilepsia. There were a total of 3 times of attacks with each interval of 6 months to 1 year, and the latest attack was 1 month before admitted to hospital. He was admitted to our hospital on September 02, 2020. Physical examination showed no cardiorespiratory abnormalities. The subsequent chest x-ray showed a mass shadow in the right upper lung(Figure 1A). The cardiac color ultrasound showed no obvious abnormalities, and no patent foramen ovale was seen. Brain magnetic resonance imaging (MRI) and cerebral arteries magnetic resonance angiography (MRA)  showed no obvious abnormalities. The contrast-enhanced transcranial doppler (c-TCD) revealed a positive result with a large right-to-left shunt. The cardiovascular CT angiography (CTA) showed the right upper pulmonary artery expanded with a diameter of 7.4mm, its branching vessels thickened and twisted into an abnormal vascular nest, then directly refluxed into the right upper pulmonary posterior vein, finaly merged into the right upper pulmonary vein(Figure 1B,1C, and1D). Blood routine test, blood gas analysis and coagulation test were normal. TIA induced by PAVF was considered. The patient underwent embolization therapy of PAVF under general anesthesia on the third day of hospitalization. Intraoperative angiography showed a PAVF originated from the right upper pulmonary branch artery (Figure 2A and 2B), which could not be revealed after embolization by a vascular plug (Figure 2C and 2D). At 1 year and 2 year postoperative follow-up, the patient remains clinical stable, no any symptom of dizziness, blurred vision or poor lower limbs movement.