Histological Demonstration of Healing in Experimental Aneurysms

Introduction: Recanalisation of aneurysms after interventional therapy is still an unsolved problem. The aim of this study is to demonstrate the angiographic and histological evidence of healing after endovascular embolisation of experimental aneurysms. Methods: We evaluated the healing reaction in experimental aneurysms treated with HydroCoils and platinum coils. After microsurgical construction of aneurysms in 24 rabbits, embolisation was performed. Four animals were sacrificed immediately after embolisation and 5 after I month, 3 months and 6 months, respectively, the remaining served as control group. Serial plastic-embedded ground sections of the parent arteries-aneurysm complexes were evaluated by light microscopy. Results: Thrombus organisation in the aneurysms resulted in fibrovascular tissue formation between bare platinum and HydroCoils from the walls of the aneurysms towards the centre of the sac over time. In the clefts between HydroCoils only thin strands of granulation tissue were observed. From one month on, there was a neointimal layer covering the coil mass at the aneurysm orifice. Conclusion: Progressive occlusion by the expanding hydrogel polymers on the coils seemed to result in a durable healing reaction in the aneurismal sac in a short-term follow-up period.