Selective intraarterial injection of ICG for fluorescence angiography as a guide to extirpate perimedullary arteriovenous fistulas

Fluorescence angiography with indocyanine green (ICG) provides real-time information regarding the patency of vessels. To enhance the capability to delineate flow direction, flow velocity and sequence of dye filling in different components of complex spinal vascular lesions such as perimedullary arteriovenous fistulas (AVFs), we tried selective intraarterial injection of ICG with catheterization in the proximity of the AVFs.Prior to taking the position for surgery, a metallic introducer sheath was placed into the femoral artery, and placed over the patient's lateral buttock. After the exposure of the AVFs, a standard angiographic catheter was advanced into the proximal portion of the feeding artery and a small volume of diluted ICG (0.06 mg in 5 ml saline for one examination) injected repeatedly. To avoid the thromboembolism, heparinized saline was perfused continuously thorough the catheter and sheath.The small injection volume and the close proximity of the injection site to the lesions resulted in quick rise and fall of the fluorescence without any background. Time and spatial resolution of analysis were enhanced; flow dynamics such as direction, velocity and alteration after temporary occlusion were well visualized. The feeders and drainers were clearly distinguished, and the shunts could be precisely identified.Selective intraarterial injection ICG fluorescence angiography was very useful for perimedullary AVFs. Albeit that it requires intraoperative selective catheterization, this repeatable technique has an advantage to improve temporary resolution and provides accurate information of the flow dynamics through the complex anatomy of vascular lesions.