Patent Application
20120197377
The present application generally relates to systems for deploying and/or retrieving intravascular stents, and more particularly relates to an apparatus including an intravascular stent delivery wire having a compliant sheath mounted over the stent delivery wire for delivery and retrieval of an intravascular stent releasably placed over the compliant sheath.
Intravascular stents are generally tubular and are actively or passively expanded radially in the vasculature of a patient. Such stent can be mounted over an expandable member or balloon of a balloon angioplasty catheter, for deployment of the stents by expansion of the balloon at the treatment site of the vasculature, such as at a stenosis or an aneurysm. Self-expanding stents can expand from a compressed delivery position to a larger diameter without the assistance of an expandable member or balloon.
Intravascular stent delivery systems for placement of an intravascular self-expanding stent at a treatment site in the vasculature typically have included a catheter that can be threaded through the vasculature with the self-expanding stent axially placed over a distal portion of the catheter. To position an intravascular stent at the treatment site of the vasculature, such as at a stenosis or an aneurysm, a guiding catheter typically is introduced into the vascular system of a patient, and advanced within the vasculature until the distal tip of the guiding catheter is adjacent to the treatment site. A guidewire is typically then advanced through the guiding catheter to the desired location, and then a dilatation or delivery catheter having a stent positioned on the catheter is advanced into the patient's vasculature over the guidewire, until the stent is properly positioned, after which the stent can be deployed at the treatment site.
One common technique for maintaining a self-expanding stent in a low profile configuration involves placement of a sheath or a sleeve over some or all of the stent, typically either to retain the stent in a compressed configuration around the catheter, to prevent body fluids from reaching the stent, or to protect the vasculature from the stent. Usually such a sheath or sleeve is retracted or released from the stent to allow the stent to achieve an expanded configuration.
A guidewire loaded stent is also known in which a radially expandable stent carried on a guidewire is covered in part by a retractable sheath at or near a distal end of the guidewire. When the stent is adjacent to a treatment site, the sheath is retracted to expose the stent to allow the stent to expand.
It would be desirable to provide an intravascular stent delivery system including an intravascular stent delivery wire having a compliant sheath mounted over the stent delivery wire for delivery and retrieval of an intravascular stent releasably placed over the compliant sheath, in order to provide a reduced diameter profile to permit delivery of an intravascular stent to smaller diameter and more delicate vessels of the vasculature, such as the neurovasculature. The present invention meets these and other needs.
Briefly and in general terms, the present invention provides for an apparatus for deploying and/or retrieving intravascular stents, including an intravascular stent delivery wire having a compliant sheath mounted over the stent delivery wire for delivery and retrieval of an intravascular stent releasably placed over the compliant sheath.
The present invention accordingly provides for an apparatus for deployment and retrieval of a self-expanding intravascular stent or a self-expanding intravascular stent-like device, including an intravascular delivery wire, and one or more bands or rings of compliant material fixedly mounted over at least a portion of the intravascular delivery wire. In a presently preferred aspect, the compliant material can be an elastomeric or polymeric material, such as silicone or polyurethane, or a tunably compliant polymeric material that can be caused to undergo a change in stiffness or compliance when subjected to temperature changes, or electricity, such as an electroactive polymer (EAP), for example. In a presently preferred aspect, the one or more bands or rings of compliant material are fixedly mounted over a distal portion of the intravascular delivery wire. In another presently preferred aspect, the one or more bands or rings of compliant material include a plurality of rings of compliant material.
In one presently preferred aspect, the distal portion of the intravascular delivery wire can have the same diameter as the proximal portion of the intravascular delivery wire. In another presently preferred aspect, the intravascular delivery wire is a stepped intravascular delivery wire, wherein the distal portion of the intravascular delivery wire is a stepped distal portion having a smaller diameter than the proximal portion of the intravascular delivery wire, forming a hard stop proximal to the one or more bands or rings of compliant material to restrict or prevent movement of a self-expanding intravascular stent releasably mounted over the one or more bands or rings of compliant material proximally over the intravascular delivery wire.
In another presently preferred aspect, a distal band or ring of compliant or non-compliant material having a diameter larger than a diameter of the intravascular delivery wire is fixedly mounted to the intravascular delivery wire distal to the one or more rings of compliant material, and a proximal band or ring of compliant or non-compliant material having a diameter larger than a diameter of the intravascular delivery wire is fixedly mounted to the intravascular delivery wire proximal to the one or more rings of compliant material. In a presently preferred aspect, the distal and proximal bands or rings of compliant or non-compliant material form hard stops configured to restrict movement of the self-expanding intravascular stent or a self-expanding intravascular stent-like device until the self-expanding intravascular stent or self-expanding intravascular stent-like device has achieved an expanded configuration. In another presently preferred aspect, the distal and proximal bands are radiopaque marker bands.
In another presently preferred aspect, a self-expanding intravascular stent is releasably retained on the one or more bands or rings of compliant material, such as by pressing or crimping the self-expanding intravascular stent on the one or more bands or rings of compliant material, to releasably mount the self-expanding intravascular stent over the one or more bands or rings of compliant material on the intravascular delivery wire.
These and other features and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments in conjunction with the accompanying drawings, which illustrate, by way of example, the operation of the invention.
Referring to the drawings, which are provided by way of example, and not by way of limitation, the present invention provides for a system and apparatus for deploying and/or retrieval of a self-expanding intravascular stent or a intravascular stent-like device.
Accordingly, an apparatus 10 for deploying and/or retrieval of a self-expanding intravascular stent 12 or a self-expanding intravascular stent-like device includes an intravascular delivery wire 14, over which one or more bands, rings, or sheaths of compliant material 16 is overlaid. The compliant material is defined herein as a compliant material that undergoes elastic deformation when subjected to an applied force. The compliant material can be an elastomeric or polymeric material, such as silicone or polyurethane, for example, although other similar materials that undergo elastic deformation when a stent or stent-like device is pressed or crimped on the compliant material may be suitable. Alternatively, the compliant material can be a tunably compliant polymeric material that can be caused to undergo a change in stiffness or compliance when subjected to temperature changes, such as undergoing a softening when heated, or that can be caused to undergo a change in stiffness or compliance when subjected to controlled application of electrical voltage or current, such as an electroactive polymer (EAP), for example. As is illustrated in
As is illustrated in
In a third embodiment, illustrated in
In a fourth embodiment, illustrated in
In each of the foregoing embodiments, a self-expanding intravascular stent or self-expanding intravascular stent-like device can be pressed or crimped onto the band, ring or sheath of compliant material or series of bands or rings of compliant material, to mount the self-expanding intravascular stent or intravascular stent-like device over the compliant material on the intravascular delivery wire. Friction between the compliant material and the intravascular stent allows the intravascular stent to be releasably retained on the compliant material for purposes of deployment and retrieval of the intravascular stent. If the compliant material is sufficiently compliant, the stent can be embedded into the layer of compliant material, which will further enhance deployment/retrievability of the intravascular stent.
It will be apparent from the foregoing that while particular forms of the invention have been illustrated and described, various modifications can be made without departing from the spirit and scope of the invention. Accordingly, it is not intended that the invention be limited, except as by the appended claims.
