RESUMO
OBJECTIVE: To characterize dynamic changes of arteriovenous malformation using a microscope-integrated technique at the moment of performing intraoperative fluorescein videoangiography (FL-VAG) at each of the resection phases. METHODS: We prospectively recruited 12 patients with arteriovenous malformations and used FL-VAG as an ancillary technique for resection of the lesion. We analyzed transit time (TT) of FL in arterial feeders (arterial transit time [TTa]) and draining veins (venous transit time [TTv]) during the different stages of resection. To achieve this, we recorded 3 values of TT of FL (TTa, initial TTv, final TTv); when final TTv was markedly slower than initial TTv, we hypothesized that the nidus was devascularized enough and could be safely removed. RESULTS: No mortality or morbidity was related to use of FL. In most cases, TT values of arterial feeders and draining veins allowed an easier distinction between them. At advanced stages of resection, FL-VAG assessed increase in TTv (venous blood slower or absent), suggesting that most feeding arteries had been obliterated, indicating the appropriate moment for nidus removal. Optimal dose of FL was a 75-mg bolus followed by injection of 20 mL of saline solution. CONCLUSIONS: FL-VAG allows a distinction of normal from abnormal flow in draining vessels and might help the surgeon to decide when the nidus can be safely removed. This is the first study prospectively evaluating this technique, and it proposes an ideal dose for brain arteriovenous malformation surgery, in contrast to doses used in tumor cases.