Intra-operative cerebral blood flow assessment by indocyanine green video-angiography after temporary arterial occlusion in aneurysm surgery and its clinical implications: a prospective study

OBJECTIVE: Indocyanine green video angiography (ICG-VA) is a routine while performing vascular surgery to assess patency of perforators, completeness of clipping and/or to assess patency of anastomosis. Its usefulness in assessing cerebral blood flow and perfusion is not well studied. This study is aimed to assess the cerebral blood flow and perfusion after temporary clipping and to correlate with the risk of ischemia. METHODS: Prospective analysis of intra-operative ICG-VA performed during temporary arterial occlusion in 38 patients from January 2014 to December 2018 was conducted. Co-relation with post-operative MR diffusion weighted imaging (MR DWI) in terms of vascular territory of interest within 48 hours of surgery was performed. Clinical outcome was assessed using modified Rankin Scale (mRS) score 1-month post-surgery. RESULTS: 43 aneurysms in 38 patients clipped using ICG-VA were included in this study. No side effect of ICG dye was seen in any patients. The number of times temporary clips applied had a direct relationship to the delay in appearance of ICG in the surgical field which became statistically significant after application of 3rd temporary clip. Nine (23.7%) patients developed ischemia following the procedure confirmed by post-operative MR DWI and all the ischemic cases had visible decrease in ICG fluorescence post-temporary clipping. CONCLUSIONS: No previous study had tried to assess the intraoperative cerebral blood flow and perfusion during temporary clipping of parent vessels during aneurysm surgery. The use of ICG-VA can be extended to assess perfusion in desired territory by merely assessing the degree of opacification.