Experimental Research On Coiling Of Rabbit Model Aneurysms With Self-made Controllable Electrolytic Detachable Microcoils

AimEndovascular management of intracranial aneurysms with metal microcoils was an effective and safe method, and has become a routine clinical performance. While all the microcoils were made in United states of American or Europe and the price of them are so expensive as to a lot of patient can not afford it which limited its clinical use. This study focused on self-made microcoils and carried on basic research to evaluate the performance, manipuility, safety and efficacy of self-made electrofusable controllable microcoil by embolizing the aneurysms of rabbit model and provide experimental proof for further clinical use of this kind of coil.MethodsPart one: Manufacture of microcoil and evaluation of its performance in vitroMicrocoils were made by welding free coils and transporting microguding wire under microscope with microelectronic technique. Anti-strain, anti-torque tests were carried on under untwisting first class spiral of coil and untwisting second class spiral. Compliance and antifatigue of microcoil were tested by repeated push and pull inside microcatheter under pressurized transfusion or no pressurized transfusion. In vitro test of detachable time of microcoils was carried out by putting through direct current with 10.2 voltage, 2.0 mA and 7.2 voltage, 1.0 mA under normal saline and in vivo test was carried out by introducing the microcoil into kidney artery of rabbit through microcatheter and detached under direct current of 10.2 voltage.Part two: Embolization of rabbit model aneurysm and evaluation of efficiencyRabbit models with common carotid artery sideway aneurysms were made and were divided into three groups according to different timing of angiography examination after operation respectively immediately, at two weeks and at four weeks. After verification the quality in vitro, the coils were used to embolize the experimental aneurysms. Angiographies were made respectively at one week, four weeks and three months after embolization. The coiled aneurysms were pathological examined after rabbit models were sacrificed.ResultsPart oneThe intensity of anti-strain at 10 mm and 100mm point proximal to connection point were 68.34±9.05cN and 83.53±2.47 cN respectively under the condition of untwisting of microcoils, and were 73.36±8.72 cN and 82.07±1.93 cN when normal; the intensity of anti-torque at the two points were 46±10 rounds and 72±8 rounds when untwisting and 134±13 rounds and 165±5 rounds when normal. In vitro test showed that detachable time was 2'34"±23" and 3'10"±42" with direct current of 10.2V,2.0mA and 7.2V,1.0mA respectively, and in vivo test showed the time was 2'12"±15". Test showed the compliance and antifatigue were satisfactory.Part twoTen qualified experimental aneurysms were coiled with 28 coils among 13 animal models. Total occlusion was got in 90% of the aneurysms immediate after treatment, in 90% aneurysms at one week, in 85% at four weeks and 80% at three months. Pathological examinzation showed that the intima of aneurismal wall were destroyed, clots formed around the coil mesh and new intima covered the neck of aneurysms.ConclusionPhysical properties such as anti-strain, anti-torque and detaching time of this self-made microcoil was as same as or similar to the metal coil available in clinic. The experiment of coiling aneurysms on rabbit model showed that this kind of self-made controllable microcoil has good manipuility and high safety. Efficacy of the coil on treatment of aneurysms was verified by late angiographies and pathological examinations. This study provided proof for further clinical study of this coil.