Double spiral patent foramen ovale closure clamp
The present invention provides a device which is adapted to press together the septum primum and the septum secundum between the atrial chambers to close any tunnel in the septum. The device in its preferred form has two clamping members, one on each side of the septum and a central connector which connects the two clamping members and passes through the tunnel. The device is configured to conform to the anatomy such that the tunnel is not substantially deformed by the device. The central connector, in its preferred form has two wires that are spaced apart so that the wires are proximate the lateral sides of the tunnel. The spacing allows the device to be centered at an appropriate location.
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This application claims priority to provisional patent application 60/528,022 filed Dec. 9, 2003.
FIELD OF THE INVENTIONThe present invention relates to devices and methods which are used to close septal openings. In particular, this invention is directed to devices and methods which are used to close a patent foramen ovale (PFO) in the septum between the left atrium and right atrium.
BACKGROUND OF THE INVENTION A PFO, illustrated in
The foramen ovale serves a desired purpose when a fetus is gestating in utero. Since blood is oxygenated through the umbilical chord, and not through the developing lungs, the circulatory system of a heart in a fetus allows the blood to flow through the foramen ovale as a physiologic conduit for right-to-left shunting. After birth, with the establishment of pulmonary circulation, the increased left atrial blood flow and pressure results in functional closure of the foramen ovale. This functional closure is subsequently followed by anatomical closure of the two over-lapping layers of tissue the septum secundum 14 and septum primum 15. However, a PFO has been shown to persist in a number of adults.
The presence of a PFO is generally considered to have no therapeutic consequence in otherwise healthy adults. However, patients suffering a stroke or transient ischemic attack (TIA) in the presence of a PFO and without another cause of ischemic stroke 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.
Accordingly, patients with an increased future risk 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. The use of these drugs can alter a person's recovery and necessitate adjustments in a person's daily living pattern.
In certain cases, such as when anticoagulation is contraindicated, surgery may be necessary or desirable to close the PFO. The surgery would typically include suturing a PFO closed by attaching the septum secundum to the septum primum. This sutured attachment can be accomplished with either an interrupted or a continuous stitch and is a common way a surgeon shuts a PFO under direct visualization.
Umbrella devices and a variety of other similar mechanical closure designs, developed initially for percutaneous closure of atrial septal defects (ASDs), have been used in some instances to close PFOs. These devices have the potential to allow patients to avoid the potential side effects often associated with anticoagulation therapies and the risks of invasive surgery. However, umbrella devices and the like which are designed for ASDs are not optimally suited for use as a PFO closure device.
Currently available designs of septal closure devices present drawbacks, including that the implantation procedure is technically complex. Additionally, there are not insignificant complication rates due to thrombus, fractures of the components, conduction system disturbances, perforations of heart tissue, and residual leaks. Many devices have high septal profile and may include large masses of foreign material which may lead to unfavorable body adaptation of a device. Since ASD devices are designed to occlude a hole, many lack anatomic conformability to the PFO flap-like anatomy. That is, when inserting an ASD into the heart to close a PFO, the narrow opening and the thin flap may form impediments to proper deployment. Even if an occlusive seal is formed, the device may be deployed in the heart on an angle which could leave some components not securely seated against the septum. Finally, some septal closure devices are complex to manufacture, which may result in lack of consistency in product performance.
Nitinol (an alloy of nickel and titanium) is known to be used in medical devices because of its biocompatablity and, especially, its unique properties. Nitinol is a member of a class of materials which exhibit shape memory characteristics. Specifically, nitinol has the ability to “remember” a shape and, after being deformed, will return to that shape once a certain temperature is reached. Hence, nitinol has been used to create medical devices that have a desired configuration in the body, e.g., a vena cava filter. The device is deformed into a delivery configuration (generally a reduced profile for delivery through a catheter). Once the device is delivered to the desired site, the nitinol changes configuration into the desired shape upon achieving a certain temperature. This is generally considered thermal responsive shape memory. Nitinol, and other materials, also exhibit superelastic shape memory. In this case, the nitinol can be restrained in a delivery configuration and then will return to the desired configuration as the device leaves the delivery catheter. Of course, some devices can be a combination of thermally induced shape memory and superelastic shape memory.
The present invention is designed to address these and other deficiencies of the prior art septal closure devices.
SUMMARY OF THE INVENTIONThe present invention provides a device which is adapted to press together the septum primum and the septum secundum between the atrial chambers to close any tunnel in the septum. The device in its preferred form has two clamping members, one on each side of the septum and a central connector which connects the two clamping members and passes through the tunnel. The device is configured to conform to the anatomy such that the tunnel is not substantially deformed by the device. The central connector, in its preferred form has two wires that are spaced apart so that the wires are proximate the lateral sides of the tunnel. The spacing allows the device to be centered at an appropriate location.
In a preferred form of the device, the clamping members are spirals which are formed from nitinol. The spirals may be constructed of wire, or alternatively, may be constructed of nitinol sheets which have been cut or shaped to form the spirals. The spirals may circle around more or less than 360 degrees and may have the a helical form. In one preferred embodiment the connector may be attached to the inner end of the wire that forms the spiral, in another, the connector may be attached to the outer end of the wire that forms the spiral. Of course, depending on the desired configuration, the connector may be connected to the inner location on one side of the device and the outer location on the other side of the device.
The clamping member may be a spiral or some other structure or configuration which secures the septum together. For example, a plurality of wires may be used which could be spread out along the septum to provide the desired clamping force. Other shapes and orientations could be used which would spread the clamping force over a sufficient surface area to accomplish the desired effect.
The connecting member may be two or more wires which are configured to spread apart in the PFO tunnel. The spacing of the wires is sized to center the device in the desired clamping location in the septum. In one preferred embodiment, the wires are joined at ends and bow apart from each other to fit within the PFO tunnel. Alternatively, the wires may form an S-shaped curve to improve the centering location. Other shapes and configurations are possible.
In an alternate form the connecting member may be formed of thin wires that are wound into a helix (e.g., in the shape of a coil spring). The connecting member may have one or more helically wound wires that form the connecting member. The resultant connector may be shaped in the same manner as the other embodiments. In other embodiments, the connecting member may have an abrasive surface so that a healing response may be stimulated by the abrasive surface. Additionally, the abrasive surface may be directionally oriented. That is, if one were to feel the surface of the wire in one direction, the wire would feel smooth and in the other direction, the wire would feel abrasive or rough.
In still other embodiments, the connecting member may include a film which extends between the connecting wires. The film may be comprised of and/or impregnated with biological and/or bioresorbable material. In another embodiment a joint may be formed at a location along the length of the connecting member. The joint reduces the trauma of the closure device within the PFO. The device may also have a hook or some other piercing element to maintain the PFO closure device in the desired location. Of course, each of the configurations could be used in combination.
The device, in its preferred form, is adapted to be delivered through a catheter into the atria. The device is constrained into a delivery profile and introduced into a catheter for delivery to the heart. Once the catheter is located at the desired delivery site, the device is deployed into the site and changes shape into the desired configuration. The shape change could be a result of a thermally induced shape change or a change due to the superelastic character of the material. Once in the delivery location, the catheter is withdrawn.
BRIEF DESCRIPTION OF THE DRAWINGS
With reference to
Referring to
With continued reference to
The ball 30 of the right atrial spiral section 20 may be grasped and drawn into a protective sheath. As the free end 28 of the right atrial spiral section is drawn inwardly into the protective sheath, the coils of the spiral section straighten as they are drawn into the sheath until the inclined central loop 22 is reached. Then as the central loop enters the sheath, the sides of the central loop are compressed together, and as the central loop is enclosed by the sheath and moves inwardly, it draws the loops of the left atrial spiral section 18, beginning with the innermost loop 26, as a straight section into the sheath.
In
The spiral sections 18 and 20 are formed to be urged toward one another. Also, since the loops of each opposed spiral section 18 and 20 are in different planes and since the inclined central loop 22 joins the innermost loops 26 of each spiral section, the spiral section 18 will draw the spiral section 20 against the atrial septum once it is deployed from sheath 32.
Since the inclined central loop 22 which joins the spiral sections 18 and 20 is seated in the PFO channel, it prevents shift or rotation of the spiral sections which might occur if a straight non-looped joined piece was used between the spiral sections.
To form the double spiral PFO closure clamp 16, an elongate length of wire is formed upon each of the cone shaped sections 38 and 40 as shown in
With reference to
As shown by
To form the left atrial spiral section 80 in opposed alignment with the right atrial spiral section, the outermost loop 90 is connected to the top of the central loop 82 at 92 as shown by
The outermost loops 84 and 90 are configured to position the left atrial spiral section and right atrial spiral section in aligned, opposed relationship.
Instead of connecting the two spiral sections 78 and 80 with a central loop which rests in the PFO channel, the central loop can be replaced with the double “S” shaped connector 96 of
With reference to
As shown in
The double spiral PFO closure clamp 76 can be straightened with a tubular delivery device for delivery and may be delivered across the PFO by catheter using a pusher wire. The left atrial spiral section 80 is delivered first into the left atrium and flattened against the septum. The central double “S” shaped connector 96 is then unsheathed in the PFO channel, and finally the right atrial spiral section 78 is released against the septum in the right atrium.
Other configurations for the wires of the center joint are possible.
In another configuration, illustrated in
In the embodiment of the invention illustrated in
In a slightly modified configuration, the wires may be provided that are in a configuration illustrated in
Claims
1. A device adapted to press together the septum primum and the septum secundum between the atrial chambers, the device comprising:
- two clamping members, one on each side of the septum and a central connector which connects the two clamping members and passes through the tunnel wherein the central connector includes two wires that are spaced apart at a portion of their length so that the wires are proximate the lateral sides of the tunnel so that the device may be centered in a passage between the atrial chambers.
2. The device of claim 1 wherein at least one of the clamping members include elongate wire members that are spiral shaped.
3. The device of claim 2, wherein the central connector is connected to at least one clamping member at an inner part of the spiral shape.
4. The device of claim 2, wherein the central connector is connected to at least one clamping member at the outer part of the spiral shape.
5. The device of claim 2, wherein the force applied to the septum primum and septum secundum is created by the spiral shape of the elongate member.
6. The device of claim 1 wherein the clamping members are formed from nitinol.
7. The device of claim 1, wherein the central connector is formed from nitinol.
8. The device of claim 1, wherein the central connector is adapted to center the device in the lateral direction along a longitudinal passageway.
9. The device of claim 2, wherein the claimping members are constructed of nitinol sheets which have been shaped to form the spirals.
10. The device of claim 2 wherein the spirals circle around more than 360 degrees.
11. The device of claim 10 wherein the spirals have a helical form.
12. The device of claim 1, wherein the clamping members are formed by a plurality of wires and the wires are adapted to spread out along the septum to provide a desired clamping force.
13. A connecting member for a PFO closure device configured to join two end pieces adapted to be disposed along a Patent Foramen Ovale tunnel, the connecting member comprising at least one wire that forms an S shaped curve wherein the outermost lateral sides of the S shaped curves are configured to be adjacent the lateral sides of the Patent Foramen Ovale tunnel.
14. The connecting member for a PFO closure device of claim 13 wherein the connecting member includes a wire that is helically wound to minimize trauma to the PFO tissue.
15. The connecting member for a PFO closure device of claim 14 wherein the connecting member includes a helically wound wire wrapped around a central wire that provides stability to the connecting member.
16. The connecting member for a PFO closure device of claim 13 wherein the connecting member includes whiskers to facilitate the implantation of the device at an implantation location.
17. The connecting member for a PFO closure device of claim 13 wherein the surface of the connecting member is roughened to facilitate implantation of the device at an implantation location.
18. The connecting member for a PFO closure device of claim 17 wherein the surface of the connecting member is roughened such that friction along the wire from movement in one direction is higher than movement along the wire in the opposite direction.
19. The connecting member for a PFO closure device of claim 13 wherein at least one of the wires includes at least two wire segments joined at a location such that the wires are able to move with respect to on another.
20. The connecting member for a PFO closure device of claim 19 werein the at least two wires are joined by a trailer hitch-type joint.
21. A connecting member configured to join two end pieces adapted to be disposed along a Patent Foramen Ovale tunnel, the connecting member comprising at least two wires that are joined at each end and spread apart between the ends, wherein wires are adapted to spread out a predetermined amount that is less than a predetermined distance between the lateral sides of a Patent Foramen Ovale tunnel.
22. The connecting member for a PFO closure device of claim 21 wherein the connecting member includes a wire that is helically wound to minimize trauma to the PFO tissue.
23. The connecting member for a PFO closure device of claim 22 wherein the connecting member includes a helically wound wire wrapped around a central wire that provides stability to the connecting member.
24. The connecting member for a PFO closure device of claim 21 wherein the connecting member includes whiskers to facilitate the implantation of the device at an implantation location.
25. The connecting member for a PFO closure device of claim 21 wherein the surface of the connecting member is roughened to facilitate implantation of the device at an implantation location.
26. The connecting member for a PFO closure device of claim 25 wherein the surface of the connecting member is roughened such that friction along the wire from movement in one direction is higher than movement along the wire in the opposite direction.
27. The connecting member for a PFO closure device of claim 21 wherein at least one of the wires includes at least two wire segments joined at a location such that the wires are able to move with respect to on another.
28. The connecting member for a PFO closure device of claim 27 wherein the at least two wires are joined by a trailer hitch-type joint.
29. The connecting member for a PFO closure device of claim 21 wherein the at least two wire are adapted to have a hook to pierce the tissue where the device is intended to be implanted.
30. The connecting member for a PFO closure device of claim 21 further comprising a membrane attached to the connecting member.
31. The connecting member for a PFO closure device of claim 21 wherein the connecting member includes a surface coating that promotes tissue growth.
32. The connecting member for a PFO closure device of claim 13 further comprising a membrane attached to the connecting member.
31. The connecting member for a PFO closure device of claim 13 wherein the connecting member includes a surface coating that promotes tissue growth.
33. The device of claim 1 further including a membrane attached to the connecting member.
34. The device of claim 1 wherein the connecting member includes a surface coating that promotes tissue growth.
Type: Application
Filed: Dec 9, 2004
Publication Date: Dec 8, 2005
Applicant: NMT Medical, Inc. (South Boston, MA)
Inventors: David Widomski (Wakefield, MA), Carol Devellian (Topsfield, MA), Morris Simon (Boston, MA), Morris (Mrs.) (Boston, MA)
Application Number: 11/008,539