EXPERIMENTAL-STUDY OF COIL EMBOLIZATION USING A NEW ATELOCOLLAGEN SPRING COIL

Spring steel coils have been used to occlude abnormal vessels in patie nts with a congenital heart malformation. However, longterm adverse ef fects of steel spring coils remain uncertain, although some long-term results appear to be good. The purpose of this study was to evaluate t he angiographic and histologic results of coil embolization experiment ally using a biodegradable atelocollagen coil that we have recently de veloped. The spring coil was made from a 30% atelocollagen solution mi xed with a contrast medium. The delivery system consisted of a 5-F end -hole catheter and a 3-F modified biotome catheter as a catch and rele ase system. Coil embolization was percutaneously attempted in 12 dogs, and only one coil was placed in each dog so that a variety of endothe lial coverage could be evaluated both in complete and incomplete occlu sion. At 1 wk to 5 mo after the procedure, the occluded vessels were r esected and examined histologically. Postprocedural angiography showed complete occlusion in 6 of the 12 vessels and partial occlusion in 6. Follow-up angiography showed complete occlusion in 8 and incomplete o cclusion in 4. Histologic examination revealed that diffuse thrombosis around the coil loops and the exchange between blood and contrast med ium were detectable as early as 7 d after embolization. Atelocollagen was gradually replaced with fibrous tissue and became markedly degrade d by 5 mo. Atelocollagen spring coils can be used to occlude abnormal vessel effectively and safely. The histologic reactions and the fate o f the coil seem to be within tolerable limits. This experimental study supports the feasibility of a clinical trial of this coil embolizatio n in patients with an aorticopulmonary collateral artery.