Peripheral Embolization Using Hydrogel-Coated Coils Versus Fibered Coils: Short-Term Results in an Animal Model

To angiographically compare the occlusive effects of hydrocoils and fibered coils in the renal and internal iliac arteries at 24 h and 7 days in the sheep model. To determine the occlusive mechanism by hydrocoils and fibered coils by pathological examination.

Two types of peripheral hydrogel-coated and fibered coils similar in diameter and length were compared. The right and left renal arteries were embolized with 0.018-inch detachable hydrocoils or fibered coils in six sheep. Then, the right and left internal iliac arteries were embolized with 0.035-inch pushable hydrocoils or fibered coils. Arterial recanalization was evaluated at 24 h and at 7 days with angiography. At pathology, the surface percentage of thrombus and embolic material (platinum, Dacron fibers and hydrogel) and the presence of inflammation were assessed.

No difference was found between the coils for recanalization at 24 h or 7 days. For hydrocoils, the surface of occlusion corresponded to thrombus for 42% and coil for 58% including 42% of platinum and 16% of hydrogel, respectively. For fibered coils, the surface of occlusion was composed of thrombus for 69% and of platinum and fibers for 31%. The surface percentage occupied by thrombus was significantly lower for hydrocoils than for fibered coils (p = 0.0047). The surface percentage of embolic was also different between the two products (p = 0.049). No degradation of hydrogel was found at any time points.

The percentage of thrombus was significantly less with hydrocoils as compared to fibered coils, which may account for reduced long-term recanalization.