The endovascular treatment of a variety of maladies throughout the body is an increasingly more important form of therapy. One such procedure uses embolizing coils to occlude a target site by posing a physical barrier to blood flow and/or by promoting thrombus formation at the site. Such treatments can be useful where it is desired to reduce vascularization, including treatments for aneurysms and cancer.
Coils have typically been placed at the desired site within the vasculature using a catheter and a pusher. As a first step, a flexible, small diameter catheter can be guided to the target site through the use of guidewires or by flow-directed means such as balloons placed at the distal end of the catheter. Once the site has been reached, the catheter lumen is cleared by removing the guidewire (if a guidewire has been used), and the coil is placed into the proximal open end of the catheter and advanced through the catheter with a pusher. Pushers are wires having a distal end that is adapted to engage and push the coil through the catheter lumen as the pusher is advanced through the catheter. When the coil reaches the distal end of the catheter, it is discharged from the catheter by the pusher into the vascular site.
Several techniques have been developed to enable more accurate placement of coils within a vessel. In one technique the coil is bonded via a metal-to-metal joint to the distal end of the pusher. The pusher and coil are made of dissimilar metals. The coil-carrying pusher is advanced through the catheter to the site and a small electrical current is passed through the pusher-coil assembly. The current causes the joint between the pusher and the coil to be severed via electrolysis. The pusher may then be retracted leaving the detached coil at an exact position within the vessel. In addition to enabling accurate coil placement, the electric current may facilitate thrombus formation at the coil site. A perceived disadvantage of this method is that the electrolytic release of the coil requires a period of time so that rapid detachment of the coil from the pusher does not occur.
Another technique for detaching an embolic coil uses a mechanical connection between the coil and the pusher. For example, one such device uses interlocking clasps which are secured to each other by a control wire that extends the length of the catheter. Retraction of the control wire uncouples the coil from the pusher.
While mechanical connections between coils and pusher wires allow quick delivery, such systems require additional control mechanisms (i.e., control wires) to deploy the coil. In addition, mechanical connections can suffer from unwanted detachment during delivery through a catheter. Accordingly, while conventional systems provide effective coil delivery, there remains room for improvement.
Disclosed herein are methods and systems for delivering an implantable device to a target site using a detachable link. The described systems overcome the drawbacks of conventional mechanical interlocks and provide a more robust coil delivery system that reduces the need to match interlocks with specifically sized catheters. In addition, the systems can reduce the chance of premature device detachment and/or jamming. In one such embodiment, the systems can include a detachable link and a device for inhibiting premature detachment of the detachable link during delivery of the implantable device through a catheter lumen.
For example, the implant delivery system can include an elongate catheter and an implantable medical device mated to a pusher wire via a detachable link comprising first and second engaging members. The first and second engaging members can include first surfaces for contacting an inner surface of the catheter and second surfaces for mating with each other. The system can further comprise an expandable member adapted to apply a force on the first and second engaging members to inhibit premature detachment or jamming of the system as the system passes through the catheter.
In one aspect, the expandable member is positioned between the first and second engaging members and adapted to expand and contract to account for variations in the internal diameter of a catheter. In a catheter having a narrow inner lumen the expandable member can compress to allow the system to pass through the catheter. Conversely, in a larger diameter catheter the expandable member can expand the width of the detachable link such that a width of the detachable link matches an internal diameter of the catheter lumen.
In addition, the force applied by the expandable member can inhibit relative movement of the engaging members to prevent premature detachment and/or jamming of the detachable link as the system travels through a catheter. For example, the expandable member can limit relative pivotal, rotation, axial, and/or radial movement of the engaging members.
In one aspect, the expandable member is an elastomer positioned between the second surface of the first engaging member and the second surface of the second engaging member. In another aspect, the expandable member is formed from a sponge material. In yet another aspect, the expandable member is a spring.
In another embodiment, an implant delivery system comprises an elongate catheter and a coil mated to a pusher wire via a detachable link comprising first and second engaging members. An expandable member is positioned adjacent to at least one of the first and second engaging members and mated therewith. In use, the expandable member can reduce relative movement between the first and second engaging members.
In one aspect, the adjacent expandable member is positioned between an outer surface of at least one of the first and second engaging members and the inner lumen of the catheter. In another aspect, the adjacent expandable member extends axially from at least one of the first and second engaging members. For example, the expandable member can be positioned within at least one of the detachable coil and the pusher wire.
In yet another embodiment, an implant delivery system comprises an elongate catheter and a detachable coil detachably mated via a detachable link comprising first and second engaging members. The system further comprises an expandable member positioned between the first engaging member and the detachable coil and an expandable member positioned between the second engaging member and the pusher wire.
In one aspect, the expandable member comprises an expandable mesh adapted to reduce relative movement between the first and second engaging members by holding the engaging members in a central portion of an inner lumen of the catheter. In another aspect, the expandable member comprises a self expanding stent adapted to reduce relative movement between the first and second engaging members.
In another embodiment, an implant delivery system comprises a coil and a pusher wire detachably mated via a detachable link comprising first and second engaging members. The system includes a sleeve extending around at least a portion of the outer surface of the detachable link. The sleeve is adapted to inhibit relative movement between the engaging members during transit through a catheter.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate illustrative embodiments of the invention and, together with the description, serve to explain the principles of the invention.
Disclosed herein are methods and systems for delivering an implantable device to a target site, particularly, a detachable, implantable device. In one aspect, such detachable, implantable devices can be mated to a pusher wire via a detachable link that comprises first and second engaging members. Discussed below are a variety of devices for preventing unwanted detachment of the detachable link during delivery of the detachable, implantable device through a catheter. In one embodiment, a compressible member expands and contracts to account for variations in the internal diameter of the catheter. In another embodiment, a sleeve is placed around at least portion of the engaging members to reduce the chance of unwanted deployment of the detachable device during delivery through the catheter.
One skilled in the art will appreciate that the embolic coil 12 and pusher wire 14 are merely representative of the environment in which detachable link 11 and expandable member 26 operate, and that a variety of alternative medical devices could be substituted. For example, the systems described herein could be used to deliver a variety of implantable devices in addition, or as an alternative, to the embolic coil. Similarly, the pusher wire represents the variety of control devices for moving an implantable device through a lumen of a medical instrument. In addition, as disclosed in co-pending application Ser. No. 11/248,033, entitled “Multiple Interlocking Detachable Coils,” filed Oct. 12, 2005, and incorporated by reference in its entirety, a second coil, or other such device, could be linked between pusher wire 14 and coil 12 via additional detachable links. Still further, while coil delivery system 10 is generally described with respect to the detachable link traveling through a catheter, one skilled in the art will appreciate that detachable link 11 may travel through a variety of medical instruments, such as, for example, introducers, and that the methods and devices describe herein are equally applicable to any medical device having a lumen for the delivery of a detachable, implantable device. In particular, the term “catheter” as used herein can refer to the variety of medical devices having an inner lumen adapted for receiving a medical instrument and/or implantable device.
Expandable member 26 allows detachable link 11 to travel through catheters having diameters larger than the outside diameter of the detachable link without detaching or jamming. For example,
In one embodiment, when expandable member 26 expands, at least a portion of at least one of outer surfaces 32, 34 of engaging members 16, 18 can be pushed against an inner surface 22 of the catheter. Contact between the outer surfaces of the engaging members 32, 34 and the inner surface 22 of the catheter allows detachable link 11 to slide through the catheter but restricts movement of the engaging members relative to the catheter wall, and thereby relative to one another. For example, with engaging members 16, 18 in contact with inner surface 22 of the catheter, the amount of relative pivotal, rotational, axial, and/or radial movement between engaging members 16, 18 can be limited.
In addition to assisting with stabilization of detachable link 11 during transit through a catheter, the expandable member can also facilitate detachment of coil 12 after detachable link 11 exits the catheter. Once detachable link has traversed catheter 20 and has been delivered, the detachable link and expandable member are no longer constrained by the catheter walls and can fully expand. The force applied by expandable member 26 on engaging members 16, 18 can help to separate the engaging members and thereby facilitate deployment.
As mentioned above, engaging members 16, 18 can have a variety of configurations adapted to releasably join coil 12 and pusher wire 14. In one aspect, the engaging members are generally configured such that opposed mating surfaces 28, 30 (
In use, end surfaces 68, 70 can allow coupled engaging members to push/pull one another. For example, end surface 68 can provide a contact area for pulling on a similar vertical surface on an adjacent engaging member (e.g., engaging member 18). When engaging member 16 is pushed, end surface 70 can be pushed by a surface (e.g., surface 72) on an adjacent engaging member. While, surfaces 68, 70, and 72 are illustrated as vertical, in another embodiment, illustrated in
Mating surfaces 28, 30 of engaging members 16, 18 can, in one embodiment, mate with expandable member 26. For example, depending on the structure and materials from which expandable member 26 is formed, the expandable member can be adhered, welded, mechanically connected, and/or otherwise fixed to the various surfaces of receiving area 60 and protrusion 62. In addition, expandable member 26 can mate with more than one of the engaging members. For example, the expandable member can be fixedly mated with both mating surfaces 28, 30. Moreover, more than one expandable member can be positioned on mating surfaces 28, 30 and can cover all or a portion of the length and width of mating surfaces 28, 30. In one aspect, mating surfaces 28, 30 can include features to assist with connecting to expandable member 26 including, for example, a recessed area (not illustrated) in which at least a portion of the expandable member is seated.
One skilled in the art will appreciate that the force and distance with which expandable member 26 expands can be varied depending on the force and distance with which one desires expandable member 26 to expand detachable link 11. Greater expansive force can increase the stability of the connection between the engaging members and result in a more robust detachable link. However, as expandable member 26 applies increasing force on engaging members 16, 18, and therefore on the wall 22 of the catheter, the amount of friction which must be overcome to move system 10 through a catheter also increases. As such, the force and distance with which expandable member 26 expands should be chosen such that the detachable link contracts/expands when placed in differently sized catheters, but does not prevent movement of the system through a catheter. One skilled in the art will appreciate that the dimensions and materials used to form expandable member 26 can be varied appropriately.
In general, expandable member 26 can be formed in whole or part by the variety of biocompatible materials having the ability to expand and contract as the detachable link is delivered through any of a variety of medical devices. In one embodiment, expandable member 26 is formed from an elastomer which can be compressed between engaging members 16, 18, and when compressed, will apply a force against the engaging members. Examples of elastomeric materials include various biocompatible materials, such as, for example silicone rubber, urethane based polymers, natural rubber, and combinations thereof. In one exemplary aspect, the elastomeric material can have a hardness in the range of about 75 Shore A and 55 Shore D.
As mentioned above, elastomeric expandable member 26 can be located on and/or mated with at least one of opposing surfaces 28, 30. For example, expandable member 26 could be adhered, mechanically, and/or frictionally engaged with surface 28 and/or 30. In one embodiment, expandable member 26 could be formed from multiple individual portions of elastomeric material positioned between engaging members 16, 18. Alternatively, expandable member 26 is formed from a unitary portion of elastomeric material.
In another embodiment, expandable member 26 can be formed from an absorbent (or adsorbent) material. In a catheter having a smaller diameter (e.g., catheter 20) the absorbent material remains compressed, but can expand in larger diameter catheters and absorb a liquid. When expandable member 26 is in an expanded configuration, the absorbed liquid within expandable member 26 can resist compression. In applications were retrograde blood flow is an issue, the use of absorbent materials can help to stem effluent. Alternatively, or additionally, fluids (such as saline solution) can be added to the catheter to provide fluid for expandable member 26 to expand. Examples of absorbent or adsorbent materials can include biocompatible sponges, adsorbent gels and polymers, ionically active materials, and combinations thereof.
In another embodiment, the expandable member could be formed by a spring.
In
A variety of different types of springs can be used with detachable link 11 including, for example, leaf spring, coiled spring, and combinations thereof.
Mating of spring 40, 40′ with engaging members 16, 18 can be achieved in a variety of ways, including, for example, adhering, mechanically attaching, and/or welding. In addition, one skilled in the art will appreciate that one, two, or more than two springs can be used to stabilize detachable link 11.
Expandable member 26 can be positioned in a variety of locations to assist with stabilizing detachable link 11 as it moves through a catheter. In one embodiment, as shown in
In another embodiment, expandable member 26′ can be positioned on an outer surface of detachable link 11.
In one embodiment, expandable member 26′ is positioned around the entire diameter of detachable link 11. Alternatively, expandable member 26′ could be positioned on just a portion or portions of the outer diameter of detachable link, such as, for example, on outer portions of engaging members 16, 18 opposite mating surfaces 28, 30. Expandable member 26′ can be formed, for example, from the various materials described above including elastomeric materials, absorbent materials, and/or springs. One skilled in the art will appreciate that one, two, or more than two expandable members can be positioned on the outer surface of detachable link 11 and/or between engaging members 16, 18.
In yet another embodiment, expandable member 26″ is positioned axially with respect to engaging members 16, 18. For example, springs 40a″, 40b″ can mate with engaging members 16, 18 and extend toward and/or into coil 12 and/or pusher wire 14. The axially extending springs can expand to contact the inner surface 22 of the catheter and apply a force against the catheter walls. With the springs set against the walls of the catheter and connected to engaging members 16, 18, the springs 40a″, 40b″ act to stabilize detachable link 11′ by resisting relative movement of engaging members 16, 18. As shown in
In one embodiment, springs 40a″, 40b″ stabilize detachable link 11 by holding the detachable link within the central portion of the catheter. The pressure of springs 40a″, 40b″ on engaging members 16, 18 can act against relative pivotal, axial, radial, and/or rotational movement of engaging members 16, 18. While detachable link is illustrated as held in a central position within catheter 20, one skilled in the art will appreciate that springs 40a″, 40b″ could alternatively be positioned to hold engaging members 16, 18 in another portion (e.g., offset) of the catheter lumen.
In one embodiment, coil 12 and/or pusher wire 14 enclose springs 40a″, 40b″. In another embodiment, the springs extend through the coil and/or pusher wire to directly contact the inner wall 22 of the catheter. For example, in
In yet another embodiment, springs 40a″ and/or 40b″ can be positioned at least partially between the detachable link 11 and coil 12 and/or between the detachable link and pusher wire 14. For example, one end of springs 40a″, 40b″ can mate to engaging members 16, 18, respectively, and the other end of springs 40a″, 40b″ can mate with pusher wire 14, coil 12, respectively.
Instead of using coiled springs between the embolic coil and/or pusher wire, expandable member 26′″ can be formed from a mesh 44. For example,
In another embodiment, a self expanding stent can be used in place of the mesh.
Regardless of the form of the expandable member (e.g., the various expandable members illustrated in
While various materials are described above with respect to the disclosed expandable members (e.g., the various expandable members illustrated in
In another embodiment, a sleeve 50 is positioned around at least a portion of the outer surfaces 32, 34 of engaging members 16, 18 to reduce the chance of premature deployment and/or jamming. For example,
The sleeve is preferably sized such that it can fit between the outer surfaces 32, 34 of the engaging members and the inner wall 22 of the catheter. For example, the sleeve can be sized such that it occupies all or a part of the distance between the outer surface of the coil delivery system and the inner wall of the catheter. In addition, in one embodiment, sleeve 50 can be compressible so that the sleeve can accommodate a variety of differently sized and shaped catheters.
Once the embolic coil is delivered to (or through) the distal end 24 of the catheter, the sleeve can be removed to allow engaging members 16, 18 to detach from one another upon delivery.
Sleeve 50 can be removed in a variety of ways. In one aspect, sleeve 50 is slid proximally with respect to the engaging members 16, 18 to allow delivery of the embolic coil. If sleeve 50 extends the full length of the catheter a physician can manipulate sleeve 50 from the proximal portion of the coil delivery system by pulling directly on the sleeve. Alternatively, the sleeve can be mated with a control wire and/or handle (not illustrated) such that that sleeve does not need to extend the full length of the catheter. In another embodiment, sleeve 50 can be formed of bioresorbable materials such that the sleeve dissolves prior to, or shortly after engaging members 16, 18 exit the distal end of the catheter. One skilled in the art will appreciate that a variety of biocompatible, dissolvable materials can be used to form the sleeve depending on the environment in which the coil is delivered and on the amount of time required/desired for deployment.
Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
This application claims priority to Provisional Application Ser. No. 60/893,720 entitled “Systems and Methods For Delivering A Detachable Implantable Device” filed Mar. 8, 2007, which is incorporated herein by reference.
Number | Date | Country | |
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60893720 | Mar 2007 | US |