Embolization is an endovascular procedure used to treat cerebral arteriovenous malformations (AVMs). AVMs are pathological shunts between arteries and veins, which bypass normal brain structures. An embolic agent commonly used to occlude AVMs is n-butyl 2-cyanoacrylate (NBCA). Although NBCA has shown to be efficacious for this application, precise knowledge of its polymerization process in vivo is needed. Inadvertent occlusion of arterial feeders proximal to the AVM nidus will occur when polymerization of NBCA is too rapid. This may lead to revascularization of the AVM. Conversely, long polymerization times may result in the occlusion of draining veins, with subsequent brain hemorrhage and pulmonary emboli. It is therefore critical to understand the kinetics of the polymerization process to obtain a complete glue cast of the arteriovenous transition (nidus) thus, yielding safe obliteration of the AVM.
In order to elucidate the polymerization kinetics of NBCA, we examined the embolization process in the femoral and subclavian arteries of the rabbit. Various embolic agents composed of NBCA/lipiodol mixtures with and without the addition of glacial acetic acid (GAA) were injected. Blood flow through the femoral and subclavian arteries was measured prior to and during embolization. All studies were recorded with high-speed digital subtraction angiography (DSA). Preliminary analysis of the data suggests that flow decay during embolization exhibits a behavior that can be modeled via a lagged-normal density curve. Optimized model parameters vis a vis the experimental data are related to the polymerization kinetics. These parameters can be used to form a quantitative basis of comparison for the various liquid embolic mixtures.