Angiographic and histologic analysis of experimental aneurysms embolized with platinum coils, Matrix, and HydroCoil

Abstract

Background and purpose: A report directly comparing platinum coils, Matrix coils, and HydroCoils in a single animal model does not currently exist. We evaluated and compared the performance of these three products in the embolization of experimental aneurysms.

Methods: Thirty-three elastase-induced saccular aneurysms were created in rabbits. Aneurysms were embolized with Matrix coils (n = 15), HydroCoils (n = 9), or platinum coils (n = 9). The groups were compared with respect to the following parameters: aneurysm size, procedure duration, number and total length of devices deposited, angiographic occlusion score, and volumetric occlusion percentage. Follow-up angiographic and histologic features at 2, 6, and 10 weeks after embolization were analyzed. Groups were compared by using analysis of variance and chi2 tests.

Results: No significant differences were found among groups regarding aneurysm size, total device length, initial angiographic occlusion score, or procedure time. The mean number of devices for Matrix subjects was less than that for platinum coils (P = .02) and HydroCoil (P = .03). Volumetric occlusion for HydroCoil (76%) was significantly greater (P < .0001) than both platinum coils (31%) and Matrix (23%). Angiographic durability was significantly increased in the HydroCoil group compared with Matrix (P = .03). Coil compaction was found more frequently in the Matrix group (five cases, 33%) than the HydroCoil (no cases, 0%), or platinum coil groups (two cases, 22%). The Matrix group showed greater tissue reaction compared with platinum coils (P < .05).

Conclusion: In the rabbit model, the use of HydroCoils results in improved long-term occlusion rates compared with Matrix and platinum coils. The Matrix group showed an increase in inflammation and coil compaction compared with HydroCoils and platinum coils.

Fig 1.

Number 3 aneurysm in Matrix group, 2-week implant. A, Anteroposterior DSA of the brachiocephalic artery shows a moderately wide-necked aneurysm. B, Anteroposterior DSA obtained immediately after embolization with Matrix coils shows near-complete occlusion of the aneurysm. C, Anteroposterior DSA obtained 2 weeks after embolization shows marked coil compaction. D, Hematoxylin and eosin stain; original magnification, ×1.5. Coronal section obtained through the aneurysm cavity. Microcompaction and inflammation along neck are shown. E, Hematoxylin and eosin stain; original magnification, ×25. Magnification of the area shown in panel D; substantial inflammation is shown along neck.

Fig 2.

Number 9 aneurysm in Matrix group, 10-week implant. A, Anteroposterior DSA of the brachiocephalic artery shows a wide-necked aneurysm. B, Anteroposterior DSA obtained immediately after embolization with Matrix coils shows the aneurysm is nearly completely occluded. C, Anteroposterior DSA obtained 2 weeks after embolization shows slight coil compaction. D, Hematoxylin and eosin stain; original magnification, ×1.3. Coronal section obtained through the aneurysm cavity. Marked microcompaction and unorganized thrombus are shown. There is no tissue across the aneurysm neck. E, Hematoxylin and eosin stain; original magnification, ×25. Magnification of the area shown in panel D. Dense cellular infiltration near coils in the dome is seen.

Fig 3.

Number 15 aneurysm in HydroCoil group, 6-week implant. A, Anteroposterior DSA of the brachiocephalic artery shows a wide-necked aneurysm. B, Anteroposterior DSA obtained immediately after embolization with HydroCoils shows the aneurysm is nearly completely occluded. C, Anteroposterior DSA obtained 2 weeks after embolization shows the aneurysm remaining stable. D, Hematoxylin and eosin stain; original magnification, ×1.1. Coronal section obtained through the aneurysm cavity. No substantial inflammatory response is present. Microcompaction is absent. A small part of persistent unorganized thrombus is shown in the aneurysm dome. E, Hematoxylin and eosin stain; original magnification, ×10. Magnification of the area shown in panel D. Cellular fibrous tissue is shown across the neck.