Calcium alginate provides a high degree of embolization in aneurysm models: A specific comparison to coil packing

OBJECTIVE: Although flexible, current coils do not fill intracranial aneurysms to a high degree, and questions remain regarding their thrombogenic capacity. We evaluated the usefulness of calcium alginate as an embolic material for endovascular embolization in aneurysm models. METHODS: We assessed three endovascular methods of instilling calcium alginate into 10-mm sidewall and 7-mm bifurcation glass aneurysm models using a balloon catheter to sea] the aneurysm orifice: 1) instillation of alginate and subsequent instillation of the reactive component calcium chloride (CaCl2) via a single-lumen catheter, 2) simultaneous instillation of alginate and CaCl2 via a side-by-side double-lumen catheter, and 3) instillation of alginate mixed with CaCl2 delivered from a concentric-tube microcatheter. A 13-mm sidewall silicon aneurysm model was used to measure and compare the volume of calcium alginate occupying the aneurysm models. RESULTS: Instillation Method 1 did not achieve optimal filling of the aneurysm with calcium alginate. The percentage volumes of calcium alginate occupying the aneurysm were 69.2 +/- 7.7% and 84.6 +/- 5.4% for instillation Methods 2 and 3, respectively. In Method 3, calcium alginate began gelation upon leaving the catheter, entered the aneurysms in a strand form, and gelled to a mass that filled the aneurysm while conforming to its inner contour. CONCLUSION: Calcium alginate fills aneurysm models to a significantly higher degree than published results of the space filled by coils. Instillation of calcium alginate, especially in strand form, may produce an embolization that better fills and conforms to the contour of aneurysms compared with coils.