Vasoocclusion coil device having a core therein

Details Vasoocclusion coil device having a core therein Vasoocclusion coil device having a core therein

1999-10-06

2003-04-22

Robert, Eduardo C. (Department: 3732)

Surgery

Instruments

Internal pressure applicator

Reexamination Certificate

active

06551340

ABSTRACT:

TECHNICAL FIELD
This invention relates generally to medical devices, and more particularly to embolization devices, that is, devices for occluding a portion of the vascular system of a human or veterinary patient.
BACKGROUND OF THE INVENTION
Embolization of vascular occlusion devices (hereinafter generally referred to as “vasoocclusion devices”) are surgical implements or implants that are placed within the vascular system of a patient. Vasoocclusion devices are typically used either to block the flow of blood through a vessel by the formation of an embolus in the vessel, or to form such an embolus within an aneurysm stemming from the vessel. Such devices are conventionally introduced into the vascular system of the patient by a catheter, and can include a mechanical interlock to permit detachment of them from a pusher extending through the catheter.
A variety of prior implantable, coil-type vasoocclusion devices are known which include a coil having a lumen defined therein, and some kind of safety wire disposed in and extending through the lumen. The coils of such devices may themselves be formed into a secondary coil shape, or any of a variety of more complex secondary shapes adapted to the particular location at which an embolism or occlusion is to be established. A variety of thrombogenic materials may be attached to or carried by the coils of such devices to promote the formation of clots (thus, in turn, promoting the establishment of the embolism or occlusion), such as Dacron, polyester, silk or cotton fibers, filaments or the like. The coil itself, or the secondary coil shape, abuts or engages the wall of the vessel in which the device is disposed, serving to anchor the device in the vessel of interest.
For example, U.S. Pat. No. 4,994,069 to M. Ritchart et al., issued Feb. 19, 1991, discloses a flexible, coiled wire for use in small vessel occlusion. The wire has a stretched, linear condition in which it can be advanced through a catheter lumen to a selected vessel, and a relaxed, convoluted condition produced by a combination of helical windings of the wire and irregularities of the helical winding (referred to as a “memory”). The patent does not appear to suggest that the wire can itself be a conventional shape memory material, such as nitinol alloy.
Numerous similar devices have been disclosed. U.S. Pat. No. 5,749,891 issued May 12, 1998 and U.S. Pat. No. 5,582,619 to issued on Dec. 10, 1996, both to C. G. M. Ken et al., are directed to implantable vasoocclusion devices comprising a helically wound coil which is itself wound into a secondary shape. The devices can include an inner, stretch-resisting member positioned in the lumen of the coil. Possible materials for the wire making up either the coil or the inner member include stainless steel and nitinol. The device shown in FIG. 4 of the '891 patent can include multiple layers of coils, the inner member being a wire which prevents stretching of the coil during movement of it. The '619 patent also discloses a coil having a wire positioned therein to similarly prevent stretching.
U.S. Pat. No. 5,645,558 issued Jul. 8, 1997 to J. A. Horton, in FIG. 4 discloses a vasoocclusion device having a helical coil with a safety wire positioned therein for structural support. Alternatively, the internal wire may be preformed into an ultimately desired shape (for example, a sphere) and fed through the coiled strand, the coiled strand then assuming the shape of the safety wire.
Finally, FIG. 4 of U.S. Pat. No. 5,522,822 issued Jun. 4, 1996 to J. J. Phelps et al., discloses a vasoocclusion device which comprises a helical coil having an internal wire attached to end caps at both ends of the coil. The wire may be made of a shape memory material such as nitinol, while the coil is typically made of a radiopaque material such as tungsten, platinum, gold or silver.
The coil-type vasoocclusion devices in the last four of these patents can all be generally characterized in that the proximal and distal ends of the safety wire are affixed or directly secured to the respective proximal and distal ends of the coil itself. Each of these devices is of course subject to its own advantages and drawbacks during use. In general, however, and without ascribing this drawback to any of the devices disclosed in these particular patents, commercially available vasoocclusion coils do not anchor well in the target vessel and/or do not attain a shape which effectively occludes blood flow when deposited in the target vessel. This is because the only thing by which such commercially available coils apply an anchoring force against the wall of the target vessel, is the abutment force provided by the resilient return of the coils themselves to a desired shape.
It would be highly advantageous to have a coil-type vasoocclusion device in which the assistive force provided by the core to anchor the device at the location of interest, could be adjusted or selected to provide an optimal total anchoring force for the device. It would also be highly advantageous to have a coil-type vasoocclusion device which maximizes the assistive force provided by the core to anchor the device at the location of interest. It would further be highly advantageous to have a coil-type vasoocclusion device which could more readily be removed or repositioned than could prior coil-type vasoocclusion devices.
SUMMARY OF THE INVENTION
The foregoing problems are solved and a technical advance is achieved in an illustrative vasoocclusion device. More particularly, the deviceof the present invention is directed to a rapidly and reliably deployable and repositionable, self-anchoring, mechanical vascular occluder whose shape and anchoring force are predetermined by an included core having a shape memory. The device of the present invention is a coil-type vasoocclusion device having a coil with a coil lumen defined therein, the core being disposed in part or more of the coil lumen. The core can be composed of a nitinol or other shape memory material, preferably in a superelastic state, or can be composed of stainless steel, MP35N or the like. (If nitinol material is used, the nitinol need not be in its stress induced, martensite condition, however, and preferably is not in such a condition.) The core is “springy” and provides an additional, anchoring assistive force, which supplements the anchoring force provided by the coil itself and which can improve the effectiveness of the coil in several applications. The present invention can be further characterized in that, unlike comparable coil-type devices, the nitinol or other shape memory material core is not affixed to the coil at both of its ends. Instead, only one portion of the core is affixed to the coil, preferably one end of the core being affixed at or near one end of the coil, while the remainder of the core is not affixed to the coil.
Such an arrangement of fixing the core to the coil may advantageously allow an adjustment of the assistive anchoring force provided by the core to a coil of a given length, by selection of the length of the core. Such an arrangement may also maximize the assistive anchoring force provided by the core, since such force would not be diminished by any twisting of the core during manipulation or positioning of the coil. Further, such an arrangement may facilitate removal or repositioning of the device, since elongation of the coil when subjected to a longitudinal removing force may lessen the anchoring force supplied by the coil itself, making engagement with the introducing or removal apparatus easier.
In a first aspect, then, the present invention is directed to a vasoocclusion device for establishing an embolus or vascular occlusion in a human or veterinary patient, the device comprising: a coil having a proximal coil end, a distal coil end spaced from the proximal coil end and a coil lumen defined therein extending between the proximal coil end and the distal coil end; and a core disposed in at least part of the coil lumen, the core having a proximal core end and a distal core end; and wherein one p

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