SEPTAL OCCLUDER AND ASSOCIATED METHODS
Devices are provided for closing septal defects such as PFOs. The devices generally include a proximal anchor member, a distal anchor member, and a flexible center joint connecting the two anchor members.
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The present application claims priority to and the benefit if U.S. patent application No. 11/326,535, filed on Dec. 19, 2002, to be issued as U.S. Pat. No. 7,867,250 on Jan. 11, 2011, which is based on and claims priority to U.S. Provisional Patent Application Ser. No. 60/340,858 filed on Dec. 19, 2001 and entitled PATENT FORAMEN OVALE (PFO) CLOSURE DEVICE WITH BIORESORBABLE COMPONENTS, each of which is incorporated by reference in its entirety.
BACKGROUND OF THE INVENTIONA patent foramen ovale (PFO) as shown in
The cause of ischemic stroke remains cryptogenic (of unknown origin) in approximately 40% of cases. Especially in young patients, paradoxical embolism via a PFO is considered in the diagnosis. While there is currently no proof for a cause-effect relationship, many studies have confirmed a strong association between the presence of a PFO and the risk for paradoxical embolism or stroke. In addition, there is good evidence that patients with PFO and paradoxical embolism are at increased risk for future, recurrent cerebrovascular events.
The presence of PFO has no therapeutic consequence in otherwise healthy adults. In contrast, patients suffering a stroke or TIA in the presence of a PFO and without another cause of ischemic stroke are considered for prophylactic medical therapy to reduce the risk of a recurrent embolic event. These patients are commonly treated with oral anticoagulants, which have the potential for adverse side effects such as hemorrhaging, hematoma, and interactions with a variety of other drugs. In certain cases, such as when anticoagulation is contraindicated, surgery may be used to close a PFO. To suture a PFO closed requires attachment of septum secundum to septum primum with a continuous stitch, which is the common way a surgeon shuts the PFO under direct visualization.
Non-surgical closure of PFOs has become possible with the advent of umbrella-like devices and a variety of other similar mechanical closure designs developed initially for percutaneous closure of atrial septal defects (ASD). These devices allow patients to avoid the potential side effects often associated with anticoagulation therapies.
BRIEF SUMMARY OF EMBODIMENTS OF THE INVENTIONVarious embodiments of the present invention are directed to devices for closing septal defects such as PFOs. The closure devices generally include a proximal anchor member, a distal anchor member, and a flexible center joint connecting the two anchor members. The center joint can be a suture. Alternatively, the center joint can be a flexible elastomeric layer, which can, e.g., be used to promote tissue ingrowth or for drug delivery. The flexible material can also be covered with a biocompatible glue to promote adherence to tissue or growth factors to accelerate tissue ingrowth.
In accordance with some embodiments of the invention, the closure device is formed of bioresorbable components such that substantially no permanent foreign body remains in the defect.
In accordance with further embodiments of the invention, mechanisms are provided to collapse the closure device for facilitating device delivery, removal and/or repositioning.
These and other features will become readily apparent from the following detailed description wherein embodiments of the invention are shown and described by way of illustration. As will be realized, the invention is capable of other and different embodiments and its several details may be capable of modifications in various respects, all without departing from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not in a restrictive or limiting sense.
Various embodiments of the present invention are directed to methods and devices for closing septal defects such as PFOs, primarily by eliciting a healing response at the defect.
As shown in
In some embodiments, the distal anchor, the proximal anchor, and the connecting member are bioresorbable. These components can be fabricated from either a single bioresorbable polymer or by a laminated composite of two or more materials to provide a unique mix of properties such as, e.g., anchor members having stiff centers and flexible edges, and blood contacting surfaces having controlled porosity or surface texture to promote fast and thorough endothelialization, while minimizing thrombosis. In addition, the tissue contacting surface of the anchors can be designed to provide added stability by, e.g., being roughened.
The distal anchor 20 is an elongated, preferably generally cylindrical, thin bar-like member with rounded, arcuately shaped ends. The tissue contacting surface of the anchor can be generally flattened to increase tissue surface contact. In size, the distal anchor component might, e.g., be 15-30 mm long and 2 mm in diameter with a circular cross-section. The proximal anchor 22 can be of similar dimensions and shape, although it can be shorter in overall length.
Other distal and proximal anchor structures are also possible. For example, the anchors can be formed of a generally flat material rolled to form a cylindrical shape as described below with respect to the embodiments of
For delivery and deployment, the distal anchor 20 and proximal anchor 22 are positioned to be generally aligned in a longitudinal, end-to-end manner within a delivery sheath or catheter 28 as shown in
An alternate delivery method for this device can be to deploy it directly through the septum primum as opposed to through the PFO.
The method of attaching the central connecting member 26 to the anchor and stop mechanism 22 to permit the distal anchor and the proximal anchor to be drawn together could be, e.g., via a friction fit or via a slip knot on the central connecting member. If a slip knot is used, the free end of the suture proximal to the knot can be held remotely and released after the knot has been placed in the appropriate location.
In one or more alternate embodiments of the invention shown in
In the embodiments illustrated in
In the
While the embodiments of
The PFO closure devices may need to be capable of x-ray visualization and use with radiopaque fillers or marker bands fabricated from noble metals such as platinum or gold. These markers can be attached using a variety of common methods such as, e.g., adhesive bonding, lamination between two layers of polymer, or vapor deposition.
Other distal and proximal anchor structures are also possible. For example, the anchors can be formed of a generally flat material rolled to form a cylindrical shape as described below with respect to the embodiments of
The center joint 56 of the
In accordance with further embodiments of the invention, a closure device can include a delivery/removal mechanism to facilitate device delivery, removal or repositioning. A device 70 shown in
The delivery and removal strings are manipulated separately in order to deploy or remove the device.
Alternatively, the delivery string 74 can be omitted, and the removal string 72 be used for both device deployment and removal. The delivery sheath 79 containing the closure device is first inserted between the septum primum and septum secundum into the left atrium in a similar manner to that shown in
As shown in
In accordance with a further embodiment of the invention, as shown in
In accordance with some embodiments of the invention, an entire closure device can be made from a single sheet of a material as shown, e.g., in the closure device 100 of
As shown in
In accordance with some further embodiments of the invention, a wire 120 such as, e.g., an S-shaped wire, can be provided to connect the proximal and distal anchor members 122, 124 of a device 126 as shown in
In accordance with further embodiments of the invention, one or more frame structures can be used as the anchor members of a closure device. For example,
A recovery suture can be attached to opposite ends of the proximate anchor member 142 to collapse the anchors for delivery in a catheter 146 as shown in
In accordance with one or more further embodiments of the invention, the distal and proximal anchors can be formed of a flat sheet-like member rolled to form a cylindrical shape as shown, e.g., in the device 170 of
The closure devices described herein can optionally be used along with suturing or stapling techniques where the anchors or flexible joints of the devices can be sewn or stapled to septum primum or secundum for better dislodgment resistance. Also, the flexible joint can, if desired, be covered with biocompatible glue to adhere to the tissue or can be loaded with drugs or growth factors to promote healing. The glue and also certain drugs can also optionally be stored in any cavities in the anchor members (e.g., in the cylindrical members of
The various closure devices described herein can include a number of advantageous features. The closure devices preferably have an atraumatic shape to reduce trauma during deployment or removal. In addition, the devices can be self-orienting for ease of deployment. Furthermore, because of the flexible center joint, the devices generally conform to the anatomy instead of the anatomy conforming to the devices, which is especially useful in long tunnel defects. In addition, the devices can preferably be repositioned or/and removed during delivery. The devices also generally have a relatively small profile after deployment. The flexible center joint of the devices can encourage faster tissue ingrowth and therefore, faster defect closure. Furthermore, there are generally no exposed thrombogenic components on the left and right atrial sides. The devices can also advantageously include bioresorbable components, which can disappear over time.
Other benefits of the devices can include possible use of a relatively small diameter delivery sheath, use of reduced or no metal mass in the device, ease of manufacturing, cost effectiveness, and overall design simplicity.
Having described preferred embodiments of the present invention, it should be apparent that modifications can be made without departing from the spirit and scope of the invention.
Claims
1. A septal defect closure device, comprising: a proximal anchor member having a generally cylindrical shape for deployment proximate a first end of a septal defect; a distal anchor member having a generally cylindrical shape for deployment proximate a second end of said septal defect; and a suture connecting said proximal and distal anchor members.
2. The device of claim 1 wherein said suture is slidingly mounted on said proximal anchor member.
3. The device of claim 2 wherein said suture includes a biasing spring at one end thereof to bias the proximal and distal anchor members toward each other when the device is deployed.
4. The device of claim 1 wherein the suture comprises a shape memory wire.
5. The device of claim 1 wherein said suture comprises a resilient elastomeric material.
6. The device of claim 1 wherein a side of each anchor member for contacting a tissue surface is generally flattened to increase surface contact.
7. The device of claim 1 wherein said proximal and distal anchor members each comprise a cylindrical structure formed by rolling a layer of material.
8. The device of claim 1 wherein said proximal and distal anchor members are inflatable.
9. The device of claim 1 wherein said device is collapsible for passage through a catheter or sheath.
10. The device of claim 9 wherein said device can be collapsed with the proximal and distal anchor members being in a generally aligned, end to end arrangement for passage through a catheter or sheath.
11. The device of claim 1 wherein said proximal and distal anchor members are collapsible for deployment or removal.
12. The device of claim 11 wherein the proximal and distal anchor members are generally foldable.
13. The device of claim 12 wherein each anchor member includes two elements separated by an elastic hinge.
14. The device of claim 1 further comprising a removal string attached to the device to facilitate removal of the device from the septal defect.
15. The device of claim 14 wherein said removal string is slidingly mounted in said proximal anchor member and attached to said distal anchor member.
16. The device of claim 14 wherein said removal string is mounted to slide through said proximal anchor member.
17. The device of claim 14 further comprising a delivery string to facilitate deployment of the device at the septal defect.
18. The device of claim 1 further comprising a wire connecting said proximal and distal anchor members to provide clamping force to close the defect.
19. The device of claim 18 wherein said wire has a serpentine configuration.
20. A method of retrieving a deployed septal closure device having a proximal anchor member positioned proximate a first end of a septal defect, a distal anchor member for positioned proximate a second end of said septal defect, and a flexible connection member connecting said proximal and distal anchor members, said method comprising: moving a sheath toward the proximal anchor member; applying tension to the proximal anchor member to first withdraw the proximal anchor member into the sheath and then to withdraw the distal anchor member into the sheath; wherein the proximal and distal anchor members are generally in an end to end, aligned arrangement in said sheath.
21. The method of claim 20 further comprising moving the sheath toward the distal anchor member prior to withdrawing the distal anchor member into the sheath.
22. The method of claim 20 wherein applying tension to the proximal anchor member comprises pulling a string attached to the proximal member.
23. The method of claim 22 wherein said string is slidingly mounted in said proximal anchor member and is attached to said distal anchor member.
24. A septal defect closure device, comprising: a proximal anchor member having a frame structure for deployment proximate a first end of a septal defect; a distal anchor member having a frame structure for deployment proximate a second end of said septal defect; and a flexible joint connecting said proximal and distal anchor members.
25. The device of claim 24 wherein said flexible joint comprises a layer of thrombogenic or inflammatory material.
26. The device of claim 24 wherein said flexible joint comprises a plurality of fibers connecting said anchor members.
27. The device of claim 24 wherein said flexible joint is porous or textured.
28. The device of claim 24 wherein said flexible joint comprises a resilient elastomeric material.
29. The device of claim 24 wherein said flexible joint comprises two layers of flexible material joined to each other generally at centers thereof.
30. The device of claim 24 wherein said anchor members each have a frame structure having a polygonal or circular structure.
31. The device of claim 24 wherein said anchor members each have a frame structure having a generally “+” shaped structure.
32. The device of claim 24 wherein said anchor members each have a frame structure having a generally “G” shaped structure.
33. The device of claim 24 wherein said anchor members each have a collapsible frame structure to facilitate deployment of said device in a delivery catheter.
34. The device of claim 24 wherein each frame structure includes metal or polymer components.
35. A septal defect closure device, comprising: a proximal anchor member for deployment proximate a first end of a septal defect; a distal anchor member for deployment proximate a second end of said septal defect; and a connecting member connecting said proximal and distal anchor members, wherein the distal and proximal anchors each comprise a layer that is rolled to form a cylinder during device deployment, and generally flat after deployment.
Type: Application
Filed: Jan 8, 2011
Publication Date: May 5, 2011
Applicant: NMT MEDICAL, INC. (Boston, MA)
Inventors: Carol A. Ryan (Topsfield, MA), Andrzej J. Chanduszko (Chandler, AZ)
Application Number: 12/987,111
International Classification: A61B 17/03 (20060101);