Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Arterial prosthesis – Stent structure
Utility Patent
1998-05-04
2001-01-02
Milano, Michael J. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Arterial prosthesis
Stent structure
C623S011110, C623S017120
Utility Patent
active
06168615
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to implantable devices for interventional therapeutic treatment of defects in the vasculature, and more particularly concerns a detachable device having multiple strut members with collapsed and expanded configurations to be used in combination with a catheter for the occlusion and reinforcement of aneurysms.
2. Description of Related Art
Recently developed interventional procedures have been used to treat defects in the vasculature which are not easily reached by surgical procedures. More particularly, such interventional procedures have been developed to treat defects that are located in small and remote vessels such as those within the brain. During such interventional procedures, vasoocclusive devices are typically placed within the vasculature of the human body by use of a catheter, either to block the flow of blood through a vessel making up that portion of the vasculature through the formation of an embolus, or to form such an embolus within an aneurysm stemming from the vessel. Vasoocclusive devices used for these procedures can have a variety of configurations, and are generally formed of one or more elements that are larger in the deployed configuration than when they are within the delivery catheter prior to placement. One anatomically shaped vasoocclusive device that forms itself into a shape of an anatomical cavity such as an aneurysm is made of a preformed strand of flexible material such as a nickel-titanium alloy. One or more of such vasoocclusive members can be wound to form a generally spherical or oval shape in a relaxed, expanded state, and can be readily deformed to fit within a small diameter catheter from which they can be deployed at a treatment site.
Aneurysms have been treated with external surgically placed clips, or using vascular catheters, by detachable vasoocclusive balloons or an embolus generating vasoocclusive device such as one or more vasoocclusive coils. The delivery of such vasoocclusive devices can be accomplished by a variety of means, including via a catheter in which the device is pushed through an opening at the distal end of the catheter by a pusher to deploy the device. By using highly flexible materials for the vasoocclusive devices, the vasoocclusive devices can be produced in such a way that they will readily pass through the lumen of a catheter in a linear shape and take on a complex shape as originally formed after being deployed into the area of interest, such as an aneurysm.
One vasoocclusive device used to treat aneurysms is a tightly wound coil that is pushed into the aneurysm through the neck of the aneurysm so that the coil forms a complex shape with the aneurysm. When an embolus generating vasoocclusive device such as a vasoocclusive coil is used to treat an aneurysm, the success of the treatment depends upon whether the embolus generating vasoocclusive device can migrate out of the aneurysm through the neck of the aneurysm, which in turn is somewhat dependent upon whether the ratio of the diameter of the dome portion of the aneurysm to the diameter of the neck of the aneurysm is less than approximately 2:1. If the dome to neck ratio is larger than approximately 2:1, the possibility that the embolus generating vasoocclusive device will migrate out of the aneurysm into the parent vessel becomes greater, posing a risk to the success of the procedure.
It would, therefore, be desirable to provide a vasoocclusive device that can be used with or without a stent, coil or the like, that can be delivered to an aneurysm or other body vessel in a primary collapsed configuration, where the vasoocclusive device can be deployed and released to assume a secondary, expanded configuration which partially occludes the neck of the aneurysm and which also allows deployment of an additional embolus generating vasoocclusive device such as an embolic coil within the aneurysm, and blocks migration of the embolus generating vasoocclusive device from the aneurysm to the vessel. It would also be desirable to provide a device which offers the advantages of a shape memory alloy such as a nickel-titanium alloy, and that incorporates radiopaque material in a stable configuration that is not subject to fracture during use of the device, so that the device can be visualized under fluoroscopy. The present invention meets these and other needs.
SUMMARY OF THE INVENTION
One problem present in the treatment of saccular aneurysms by use of interventional therapy is presented when the aneurysm is formed such that the neck of the aneurysm is relatively large in at least one dimension compared to the maximum width of the dome of the aneurysm. In such a case, it is difficult to employ an embolus generating occluding device such as an embolic coil without raising the risk that the device will partially, or fully, deploy outside of the aneurysm and into the vessel, thereby presenting a risk to the patient.
The present invention provides for an improved method and apparatus which solves these and other problems by providing, in its broadest aspect, a partially occlusive vasoocclusive apparatus with a plurality of strut members that can be deployed in an expanded configuration across the neck of a body vessel such as an aneurysm, either alone, or to additionally allow deployment of a secondary vasoocclusive device or substance within the vessel, and to block migration of the secondary vasoocclusive device into the vessel. Specifically, with respect to the treatment of aneurysms, the vasoocclusive apparatus can be deployed across the neck of an aneurysm having a less than favorable dome to neck ratio to prevent migration of a secondarily placed embolus generating vasoocclusive device from the aneurysm.
Briefly, and in general terms, a presently preferred embodiment of the present invention provides for a vasoocclusive apparatus for use in interventional therapy and vascular surgery which is adapted to be inserted into a portion of a vasculature for treatment of a body vessel such as an aneurysm. The invention can be used in conjunction with secondary vasoocclusive devices such as embolic coils that can be placed within the aneurysm and partially retained by the apparatus. The vasoocclusive apparatus of the invention comprises a plurality of strut members or spokes extending from a central hub that can be deployed within an aneurysm, and that are radially extended in an expanded configuration to cross the neck of the aneurysm, dividing the neck into smaller openings, and thus allowing the deployment of the secondary vasoocclusive device by a catheter extending through the smaller openings in the invention within the aneurysm but preventing migration of the secondary vasoocclusive device from the aneurysm once it is deployed. In one presently preferred aspect of the invention, the device is made from a twisted cable of superelastic strands made of a suitable material, with the cable including at least one radiopaque strand, made of platinum, tungsten or gold, in order to serve as a marker during a procedure. In one presently preferred embodiment, the super-elastic material comprises a shape memory material such as nickel titanium alloy, that can be heat treated to remain superelastic or to have shape memory behavior such that the alloy is highly flexible at a temperature appropriate for introduction into the body via a catheter, and after placement, the device will take on a shape designed to optimize the therapeutic purposes desired for the device. In this regard, the disclosures of co-pending applications Ser. No. 08/986,004 filed Dec. 5, 1997 and Ser. No. 09/019, 841 filed Feb. 6, 1998 describe such radiopaque strands and three dimensional vasoocclusive devices formed therefrom, are incorporated by reference herein.
In a presently preferred configuration of the vasoocclusive apparatus, the plurality of strut members are connected together at a central hub, and extend radially from the central hub from a first collapsed configuration to an expanded configuration. The strut members
Ferrera David A.
Ken Christopher G. M.
Fulwider Patton Lee & Utecht LLP
Koh Choon P.
Micrus Corporation
Milano Michael J.
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