In-vitro simulation of NBCA embolization for arteriovenous malformation

Embolization using n-butyl-cyanoacrylate (NBCA) for arteriovenous malformation (AVM) is now a daily practice over the world, but there exists no objective data that can be a basis for discussion or decision-making on the best concentration and injection rate of NBCA mixture. The purpose of this study was to obtain objective data on control and behavior of NBCA mixture with an in vitro simulation system of NBCA embolization for AVM. A nidus model made of a one-ml syringe filled with small beads was connected to a pulsatile flow circuit. A microcatheter was introduced just before the nidus model. Endoluminal pressures proximal and distal to the nidus and flow volume through the nidus were measured. Digital subtraction angiography (DSA) was performed to calculate transit time of the contrast medium (CM) through. the nidus. NBCA was injected at various rates with an autoinjector and transit time of NBCA through the nidus was calculated. 27 trials were completed. Transit time of CM through the nidus model is well correlated to flow volume per unit of time through the nidus model. Shorter the transit time, larger was the flow volume per unit of time. The correlation was statistically significant (P < .0001). Though statistical significance was not attained, transit time of NBCA mixture at 50% concentration had a tendency to be correlated to flow volume per unit of time through the nidus, and slower injection of the NB CA mixture led to slower filling of the nidus model. Though this simulation system was artificial and the results should be interpreted carefully, it was shown with this system that transit time of CM through the nidus could be a good index for flow volume per unit of time through the nidus. Also suggested was a possibility to utilize this in vitro system for research and training on NBCA embolization of AVM.