New embolization coil containing a nitinol wire core: Preliminary in vitroand in vivo experiences

PURPOSE: To improve the stability of the standard stainless steel embolizat ion coil by adding a nitinol wire core. MATERIALS AND METHODS: With use of one coil with a nitinol wire core and on e without one, stability and resistance to elongation were measured in vitr o. Thirty-one factory-made stainless-steel macrocoils equipped with preshap ed nitinol wire cores were acutely deployed into branches of the superior m esenteric artery (SMA) in five pigs (part I of the study). Fifteen homemade retrievable coils with thermal shape memory (TSM) nitinol wire cores were acutely deployed in the abdominal aortae or inferior venae cavae of four pi gs (part II). Coils with a superelastic (SE) nitinol wire core (n = 9), a T SM nitinel wire core (n = 5), and without a core (n = 5) were compared in c arotid embolization (part III). RESULTS: In vitro, the expansile strength of the reinforced coils was signi ficantly greater and elongation was significantly less than the standard co ils (P < .01). In part I, coils were easily deployed via diagnostic cathete rs. In part II, ability to reposition the coils facilitated optimal coil co nfiguration, which resulted in effective self-anchoring and occlusion. In p art III, no coils with a SE core migrated, whereas one of five with a TSM c ore and three of five without reinforcement migrated immediately. The core significantly increased coil stability and postplacement configuration (P < .01). CONCLUSIONS: Addition of a nitinol wire core increases the intravascular st ability of the standard embolization coil by significantly enhancing expans ile force and postplacement configuration. The wire core does not adversely affect the handling of the coil. The ability to reposition/retrieve the co il is a desirable feature.