Multi-layer coaxial vaso-occlusive device

Abstract

A vaso-occlusive device includes inner, intermediate, and outer elements arranged coaxially. The inner element is a filamentous element, preferably a microcoil. The intermediate element is made of a non-metallic material, preferably an expansile polymer. The outer element is substantially non-expansile and defines at least one gap or opening through which the intermediate element is exposed. In a preferred embodiment, when the intermediate element is expanded, it protrudes through the at least one gap or opening in the outer element and assumes a configuration with an undulating, convexly-curved outer surface defining a chain of arcuate segments, each having a diameter significantly greater than the diameter of the outer element. The expanded configuration of the intermediate element minimizes friction when the device is deployed through a microcatheter, thereby reducing the likelihood of buckling while maintaining excellent flexibility. The result is a device with enhanced pushability and trackability when deployed through a microcatheter.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a Continuation-in-Part of co-pending application Ser. No. 10 / 631,981; filed Jul. 31, 2003, which prior application claims the benefit, under 35 U.S.C. Section 119(e), of provisional application No. 60 / 400,103, filed Jul. 31, 2002, the disclosure of which is incorporated herein by reference.FEDERALLY-SPONSORED RESEARCH OR DEVELOPMENT [0002] Not Applicable BACKGROUND [0003] This invention relates to vaso-occlusive devices, such as vaso-occlusive coils and the like, for the embolization of vascular aneurysms and similar vascular abnormalities. Specifically, the invention is an improvement over existing two layer or two element coaxial vaso-occlusive devices, particularly those having a polymer coating or covering. In particular, the present invention is a three layer or three element coaxial vaso-occlusive device that provides improved durability, pushability, and trackability inside a microcatheter. The characteristic ...

AI Technical Summary

Benefits of technology

[0013] The outer element is advantageously a helical “over-coil” that is loosely wound (“open-wound”) over the intermediate element, except at proximal and distal end sections, where it is tightly wound (“close-wound”). The close-wound proximal and distal end sections support the inner element, protecting it from damage during deployment and any necessary repositioning, while also securely binding the intermediate element to the inner element at the proximal and distal ends of the device and restraining the hydrogel of the intermediate element from expanding at the respective ends of the device. The open-wound section between the proximal and distal end sections creates a single, continuous helical opening through which the intermediate element expands. The helical configuration of the opening forces the expanded polymeric intermediate element to assume the configuration of a chain of arcuate segments protruding radially outwardly between the coils of the over-coil, rather than that of a continuous polymeric layer having a continuous, uninterrupted exterior surface. Because each of the arcuate segments contacts the interior surface of a microcatheter (e.g., during deployment) primarily at or near a tangential contact point, the total con

Problems solved by technology

This reduced contact area correspondingly reduces the aggregate friction between the polymeric

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