Dynamic ICG Fluorescence Provides Better Intraoperative Understanding of Arteriovenous Fistulae

Abstract

Sufficient perfusion is crucial during and after vascular neurosurgical procedures. Intraoperative indocyanine green (ICG) angiography has evolved into a useful tool in aneurysm and arteriovenous malformation surgery. Semiquantitative ICG fluorescence analysis Flow 800 may, in addition, lead to a better understanding of local perfusion. We report the applicability and utility of semiquantitative ICG fluorescence in the surgical treatment of 5 patients with pial or dural arteriovenous fistulae. Five patients with pial or dural arteriovenous fistulae were operated on using intraoperative semiquantitative ICG fluorescence Flow 800 (5 mg ICG bolus via central venous line). Before and after occlusion of fistulae, rise time of parenchyma and transit time from artery to parenchyma were measured. The analysis of flow parameters allowed detection of small fistulae and revealed a significant change in flow dynamics in the draining vein after surgical occlusion. ICG "flow" analysis showed rise time and transit time to be significantly shorter comparing pre-occlusion with post-occlusion (P = .025 and P = .039, respectively), leading to a significantly enhanced perfusion of neighboring brain parenchyma. In all 5 patients, dynamic analysis of fluorescence revealed a better understanding of intravascular rheology intraoperatively, allowing confident identification and treatment of pathology. Dynamic ICG fluorescence measurements provide additional perfusion information about flow characteristics in the draining vein and tissue perfusion, which facilitates surgical treatment of arteriovenous fistulae.