Midterm Recanalization after Arterial Embolization Using Hydrogel-Coated Coils versus Fibered Coils in an Animal Model.

PURPOSE: To compare angiographic and pathologic effects (ie, occlusion, recanalization) after embolization with Hydrogel-coated coils (HydroCoils) and fibered coils in the renal and internal iliac arteries after 7 days and 1 and 4 months in an animal model. MATERIALS AND METHODS: Twelve sheep had 1 internal iliac and 1 renal artery randomly embolized with HydroCoils or fibered coils. Renal and internal iliac arteries were embolized with detachable 0.018-inch coils and pushable 0.035-inch coils, respectively. All animals had control angiography performed at 7 days, and 1 and 4 months to assess recanalization before euthanasia. Recanalization and inflammation were evaluated via pathologic examination. RESULTS: At 1 month, 100% of arteries embolized with HydroCoils were occluded vs 50% of those embolized with fibered coils (P = .004). At 4 months, 80% of arteries embolized with HydroCoils were occluded vs 25% of those embolized with fibered coils (P = .01). Surface of vessel occlusion was significantly greater for iliac arteries (96.7% ± 8.9) than for renal arteries (94.2% ± 5.3; P = .0076). Surface of occlusion of the renal arteries (92.2% ± 5.1) was lower for fibered coils than for HydroCoils (96.8% ± 4.7; P = .0287). Surface percentage of thrombus was significantly lower for HydroCoils than for fibered coils (P < .0001). Surface percentage of thrombus was correlated with surface percentage of recanalization (P = .0181). CONCLUSIONS: After 4 months, 75% of arteries embolized with fibered coils were recanalized vs 20% of those embolized with HydroCoils (P = .01). Reduced amount of thrombus after embolization with HydroCoils accounted for a reduced rate of arterial recanalization.

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

OBJECTIVES: 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. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSION: The percentage of thrombus was significantly less with hydrocoils as compared to fibered coils, which may account for reduced long-term recanalization.

Pulmonary artery chemoembolization in a sheep model: Evaluation of performance and safety of irinotecan eluting beads (DEB-IRI).

The purpose of this study was to evaluate and compare plasma pharmacokinetics, lung tissue concentration, and the potential toxicity of drug eluting beads loaded with irinotecan (DEB-IRI) in a sheep pulmonary artery chemoembolization (PACE) model. Sheep (n = 24) were embolized with DEB-IRI loaded with different doses (0, 20, 50, or 100 mg). Direct pulmonary artery (PA) injections of irinotecan were also performed at two doses (50 or 100 mg; n = 4 sheep). Irinotecan was quantified in plasma and lung tissue (liquid chromatography-fluorescence detection); pathological examination of lungs was performed 4 days or 4 weeks after PACE. Irinotecan was detected in the systemic circulation within a few minutes after PACE, for several hours in DEB-IRI 20 and DEB-IRI 50 groups, and for 24 hours for DEB-IRI 100. Both Cmax and AUC values increased significantly with dose (p = 0.0078 and p = 0.0008, respectively) after PACE. Cmax and AUC values were significantly reduced (by 80%, p = 0.0036, and by 50%, p = 0.0393, respectively) after PACE than after direct PA injection. Irinotecan was not detected in tissue 4 days after PACE. No sign of lung toxicity was observed, except a limited hemorrhagic angionecrosis seen 4 days after PACE with DEB-IRI 100. Inflammatory response on beads was moderate in all DEB-IRI groups. Compared to other routes of administration, DEB loaded with irinotecan at doses up to 100 mg was well tolerated. DEB loaded with 100 mg irinotecan seem a promising candidate for future PACE trials in patients.

Arterial distribution of calibrated tris-acryl gelatin and polyvinyl alcohol embolization microspheres in sheep uterus.

The purpose of this study was to compare, after embolization, the distribution in the uterine arterial vasculature of tris-acryl gelatin microspheres (TGMS) and polyvinyl alcohol microspheres (PVAMS). A limited bilateral uterine artery embolization was performed in six adult sheep under fluoroscopic control by injecting in each uterine artery 0.25 ml of 500- to 700-microm TGMS of PVAMS suspended in 50/50 saline/contrast medium. Sacrifices were performed 1 week after embolization and uteri were analyzed histologically. The number and size of microspheres and vessels were measured, as well as the histological location according to a classification in four zones of the uterus. One hundred sixty-five vessels (69 vessels occluded with TGMS and 96 vessels occluded with PVAMS) were measured. The size of the occluded vessels decreased significantly from proximal to distal zones of the uterine vasculature (P < 0.0001). The location of TGMS and PVAMS within the vasculature was significantly different (P < 0.0001) since PVAMS blocked significantly more distally than TGMS. Deformation of the microspheres within the tissue was greater for PVAMS (18.0% +/- 12.3%) than for TGMS (8.7% +/- 9.2%) (P < 0.0001). In conclusion, PVAMS have a more distal distribution in the sheep uterine vasculature, compared to TGMS. Such differences in partition, already described in the kidney embolization model, can ultimately explain the different clinical outcome reported with these two types of microspheres in uterine fibroid embolization.