US20120296346A1 - Clip Apparatus for Closing Septal Defects and Methods of Use - Google Patents

Abstract

A device for closing a septal defect, such as a patent foramen ovale, includes a clip formed from a superelastic material that is inserted into a septum wall of a heart. The clip is advanced through a patient's vasculature, e.g., within a delivery apparatus, until the clip is disposed within a first chamber adjacent the septal defect. Tines of the clip are directed through a flap of tissue of the septal defect until the tines of the clip are disposed within a second opposing chamber. The clip then transforms into its relaxed state, wherein the tines of the clip engage with a surface of the second chamber, thereby substantially closing the septal opening.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application is a continuation of U.S. application Ser. No. 13/150,460, filed Jun. 1, 2011, which is a continuation of U.S. application Ser. No. 12/771,945, filed Apr. 30, 2010, now abandoned, which is a continuation of U.S. Pat. No. 7,740,640, issued Jun. 22, 2010, which is a continuation of U.S. Pat. No. 6,776,784, issued Aug. 17, 2004, all of which are fully incorporated herein by reference.
FIELD OF THE INVENTION
• The present invention relates generally to apparatus and methods for treating septal defects, and more particularly to apparatus and methods for closing a patent foramen ovale or other septal defect.
BACKGROUND
• During development of a fetus in utero, blood is generally oxygenated by the mother's placenta, not the fetus' developing lungs. Most of the fetus' circulation is shunted away from the lungs through specialized vessels or foramens that are open during fetal life, but generally close shortly after birth. Occasionally, however, these foramen fail to close and create hemodynamic problems, which may ultimately prove fatal unless treated.
• One defect that may occur is a patent foramen ovale (“PFO”), which may occur between the left and right atria of the heart. During fetal life, an opening called the foramen ovale allows blood to pass directly from the right atrium to the left atrium (bypassing the lungs). Thus, oxygenated blood from the placenta may travel through the vena cava into the right atrium, through the foramen ovale into the left atrium, and from there into the left ventricle for delivery via the aorta to the fetus' body. After birth, with pulmonary circulation established, the increased left atrial blood flow and pressure causes the functional closure of the foramen ovale. This closure is then followed by the anatomical closure of the foramen ovale.
• In some humans, however, the foramen ovale fails to completely close. This condition can pose serious health risks for the individual, particularly if the individual has other heart abnormalities. For example, recent studies suggest an association between the presence of a patent foramen ovale and the risk of paradoxical embolism or stroke. See P. Lechat J et al.,Prevalence of Patent Foramen ovale in Patients with Stroke, N. Engl. J. Med. 1988; 318: 1148-1152.
• Still other septal defects may occur within a septum between the various chambers of the heart, such as atrial-septal defects (ASDs), ventricular-septal defects (VSDs), and the like. To close such defects, open heart surgery may be performed to ligate and close the defect. Such procedures are obviously highly invasive and pose substantial morbidity and mortality risks.
• Alternatively, catheter-based procedures have been suggested. These may involve introducing umbrella or disk-like structures into the heart that include opposing expandable structures connected by a hub or waist. Generally, the device is inserted through the defect, and the expandable structures are deployed on either side of the septum to secure the tissue surrounding the defect between the umbrella or disk-like structure in an attempt to seal and close the defect. Such devices, however, involve frame structures that often support membranes, either of which may fail during the life of the patient being treated, opening the defect and/or releasing segments of the structure within the patient's heart.
• Accordingly, apparatus and methods for closing septal defects, and in particular a patent foramen ovale, would be considered useful.
SUMMARY OF THE INVENTION
• The present invention is directed to apparatus and methods for closing septal defects, including, but not limited to, a patent foramen ovale.
• In a first aspect of the invention, an apparatus for closing a septal defect includes a clip formed from a elastic material having at least two penetrating tines and an opposing retaining end. The clip is biased so as to project the at least two penetrating tines distal to the opposing retaining end, wherein when the bias is removed, the at least two penetrating tines move laterally apart from one another.
• In accordance with another aspect of the present invention, a delivery apparatus for delivering a clip, such as that described above, is provided that includes an outer catheter and a pusher member that are slidably coupled to one another. The catheter may be a tubular member including proximal and distal ends and a lumen therebetween, the distal end having a size for insertion into a blood vessel or other body lumen. The clip may be carried within the lumen of the outer catheter, preferably, with the tines disposed distally to the retaining end.
• The pusher member may be an inner catheter or other elongate member that is disposed within the lumen of the outer catheter. The pusher member may include a distal end that may be disposed proximate the retaining end of the clip, the pusher member being movable axially relative to the tubular member for ejecting the clip distally from the lumen.
• An actuator may be provided on the proximal end of the tubular member and/or the pusher member for advancing the pusher member relative to the tubular member. Preferably, the actuator may limit advancement of the pusher member.
• In a further alternative, the delivery apparatus may include an imaging device including an imaging element associated with the distal end of the tubular member for imaging near or beyond the distal end of the tubular member. For example, the imaging device may be an angioscope or ultrasound device that may be received within a lumen of the tubular member or may be a separate device that may introduced independently into the patient but used in conjunction with the delivery apparatus during a procedure.
• In another alternative, the clip has a single tine and an opposing retaining end. The clip is biased so as to project the single tine distal to the opposing retaining end. When the bias is removed, the clip transforms into a geometric shape such as a “V”, “U”, “S”, or “L”. The opposing retaining end may have an optional head to prevent the clip from completely passing through the septum wall of a heart.
• In accordance with yet another aspect of the present invention, a method is provided for closing a patent foramen ovale or other septal defect within a patient's heart. Generally, the septal defect includes one or more flaps of tissue partially detached from a septum wall between first and second chambers of the heart, the flap(s) of tissue and surrounding tissue of the septum wall defining a septal opening through the septum wall.
• A clip, such as that described above, is advanced, in a stressed state, through the patient's vasculature until the clip is disposed adjacent to the septal opening. The tines of the clip penetrate the flap of tissue and pass into the second chamber of the heart. After the clip has penetrated the flap of tissue (i.e., septal defect), the clip transitions to its relaxed state so as to at least partially close the septal opening.
• It is an object of the invention to provide a clip apparatus for the closure of septal defects, such as a patent foramen ovale. It is a further object of the invention to provide a delivery device for the delivery of the clip apparatus to the defect area. It is yet a further object of the invention to provide a method of closing a patent foramen ovale using the clip apparatus. Other objects and features of the present invention will become apparent from consideration of the following description taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a cross-sectional view of a clip apparatus showing the clip in a stressed state.
• FIG. 2 is a cross-sectional view of the clip shown inFIG. 1 with the clip in a relaxed state.
• FIG. 3 is a cross-sectional view of a delivery apparatus showing a pusher member and a clip contained within a lumen of the delivery apparatus.
• FIG. 4 is a cross-sectional view of a heart including a septal foramen ovale in a septum wall of the heart. The delivery apparatus ofFIG. 3 is shown being advanced through the aortic arch.
• FIG. 5 is a perspective detail view of the septal defect shown inFIG. 4. A flap of tissue, which is partially attached to the septum, has been pierced by the clip in its stressed state.
• FIG. 6 is a perspective detail view of the septal defect shown inFIG. 4 after deployment of the clip apparatus. The flap of tissue has closed the opening after the clip has transitioned to its relaxed state.
• FIG. 7(a) is a cross-sectional view of the septum wall and delivery device, showing a method for closing the septal defect shown inFIGS. 4-6. The delivery device is shown adjacent to the flap of tissue.
• FIG. 7(b) is a cross-sectional view of the septum wall and delivery device, showing a method for closing the septal defect shown inFIGS. 4-6. The pusher member has deployed the clip through the flap of tissue.
• FIG. 7(c) is a cross-sectional view of the septum wall and delivery device, showing a method for closing the septal defect shown inFIGS. 4-6. The clip has transitioned to its relaxed state and closed the septal defect.
• FIG. 8 is a perspective view of a clip according to a separate preferred aspect of the invention. The clip is shown in its stressed state.
• FIG. 9 is a perspective view of the clip shown inFIG. 8 with the clip in its relaxed state.
• FIG. 10 is a cross-sectional view of the septum wall showing a hole-type septal defect. The clip is shown in its stressed state.
• FIG. 11 is a cross-sectional view of the septum wall showing a hole-type septal defect. The clip is shown in its relaxed state.
• FIG. 12 is a cross-sectional view of the septum wall showing a hole-type septal defect. A clip having a single tine is shown in its relaxed state.
• FIG. 13 is a cross-sectional view of the septum wall showing a hole-type septal defect. A clip having a single tine is shown in its relaxed state.
• FIG. 14 is a cross-sectional view of the septum wall showing a hole-type septal defect. A clip having a single tine is shown in its relaxed state.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
• FIGS. 1 and 2 illustrate a first preferred embodiment of aclip2 that is used for closing a septal defect (i.e., PFO, ASA, VSA), in accordance with the present invention. Theclip2 includes two penetratingtines4 that are connected to one another via an opposing retainingend6. Thetips8 of thetines4 are sharpened to aid in penetrating tissue. InFIG. 1, theclip2 is shown in its stressed state. In this regard, theclip2 may by made from an elastic material, such as stainless steel, and preferably, a superelastic material. Alternatively, theclip2 may be formed from a shape memory alloy, one example being NITINOL. Of course, other bio-compatible elastic or superelastic materials may also be employed. Theclip2 is maintained in its stressed state by restraining thetines4 from expanding outward. In this manner a biasing force is applied to theclip2. Thetines4 of theclip2 project distally from the retainingend6, as is shown, for example, inFIG. 1. Thetines4 preferably are restrained by using adelivery apparatus10, such as a catheter or the like (discussed in more detail below). Preferably, in its stressed state, theclip2 has the shape of a “U” or a “V”, as is shown, for example, inFIG. 1.
• FIG. 2 illustrates theclip2 in its relaxed state. Without the application of the biasing force, theclip2 transitions to its related configuration wherein the angle a between the twotines4 increases. Thetines4 also move laterally away from one another, as is shown, for example, inFIG. 2. In addition, portions of thetines4 closest to thetips8 may optionally inflect back upon themselves. In one preferred embodiment, in the final relaxed configuration, theclip2 preferably has the shape of a “W”, as is shown, for example, inFIG. 2.
• Depending on the type and nature of the septal defect, theclip2 may have variations in its design. For example, the length of thetines4 may be chosen depending on the size of theopening42. If the opening is larger,longer tines4 may be used. Similarly, alarger opening42 may require a greater expansion angle a for the clip. Other variations may also be present, such as the degree of inflection, if any, in the ends of thetines4 nearest thetips8. Theclip2 may be made of one piece of material or, alternatively, multiple segments.
• Referring now toFIG. 3, adelivery apparatus10 generally includes an outer catheter ortubular member12, and an inner catheter orpusher member14. Theouter catheter12 includes a proximal end (not shown), and adistal end16 having a size suitable for insertion into a blood vessel or other body lumen (not shown). Thedistal end16 preferably has a tapered or roundedtip18, e.g., for facilitating substantial atraumatic advancement of thedelivery apparatus10 through the patient's vasculature. Theouter catheter12 also includes alumen20 therein that extends between proximal and distal ends16. As shown inFIG. 3, theclip2 is contained within thelumen20 of theouter catheter12. Theouter catheter12 provides the biasing force to keep theclip2 in its stressed state.
• In one preferred embodiment of the invention, the outertubular member12 may include one or more axially disposed grooves22 (one is shown inFIG. 3) within the inner surface that engages with the tine(s)4 of theclip2. The groove(s)22 may serve as a guide for theclip2 so that the orientation of theclip2 is maintained during delivery. In this regard, theclip2 may not rotate into a different orientation as it is ejected from theouter catheter12.
• Thepusher member14 includes a proximal end (not shown) and adistal end24 having a size such that thepusher member14 may be slidably disposed within thelumen20 of theouter catheter12. Thedistal end24 may be disposed proximal to the retainingend6 of theclip2, and thepusher member14 may be moveable axially relative to theouter catheter12 for ejecting theclip2 distally from thelumen20, as is described more fully below. Optionally, thedistal end24 of thepusher member14 may contain anotch26 that engages with the retainingend6 of theclip2 for assisting in orienting of theclip2. Thenotch26 may prevent the rotation of theclip2, or alternatively, aid in rotating the clip2 (through rotation of the pusher member14) for proper orientation. Thenotch26 may be present without or in addition to the groove(s)22.
• An actuator, e.g., a handle device (not shown), may be provided on the proximal end of theouter catheter12 and/or thepusher member14.
• Use of theclip2 for closing aseptal defect30 is shown in conjunction withFIGS. 4-7(c),10, and11.FIG. 4 generally shows aheart32 of a patient, includingheart chambers34,36 separated by aseptum wall38. Theseptal defect30, which may be a PFO, ASD, VSD and the like, is shown in theseptum wall38. As best seen inFIGS. 5 and 6, theseptal defect30 may include a flap oftissue40 adjacent to anopening42 in theseptum wall38.FIGS. 10 and 11 illustrate anotherseptal defect30 wherein the defect is a hole-type ofstructure52, e.g., extending laterally through theseptum wall38.
• Thedelivery apparatus10, with theclip2 therein, may be introduced into the patient's vasculature, e.g., from a percutaneous entry site in a peripheral vessel, such as the femoral vein, jugular vein, and the like (not shown). The distal end of theouter catheter12, including theclip2, may be advanced endoluminally within the patient's vasculature, e.g., through the vena cava46 (inferior or superior) and into theheart32 until thedistal end16 is disposed within thechamber34, which is shown inFIG. 4 to be the right atrium. Alternatively, theclip2 may be introduced using an arterial approach as is commonly known in the art.
• With particular reference toFIGS. 5,6, and7(a)-(c), thedistal end16 of thedelivery apparatus10 may be advanced into contact with aproximal surface40aof the flap oftissue40, e.g., such that the flap oftissue40 is disposed proximate theseptal opening42, as shown inFIG. 7(a). Thepusher member14 may be advanced distally relative to theouter catheter12, thereby piercing thetines4 of theclip2 through the flap oftissue40 until a portion of thetines4 of theclip2 are located within thesecond chamber36 located on the opposing side of theseptum wall38, thereby creatingpunctures48 for eachtine4. The penetratingtips8 on thetines4 of the clip are preferably sharp enough to facilitate piercing and passing of thetines4 through the flap oftissue40.
• Preferably, thepusher member14 is advanced distally to aid in pushing thetines4 of theclip2 through the flap oftissue40. Thepusher member14 preferably pushes until theclip2 cannot advance further through the flap of tissue40 (i.e., the retainingend6 of theclip2 prevents further advancement). This may be accomplished by using an actuator (not shown) on thedelivery apparatus10 that permits controlled advancement of thepusher member14. For example, the actuator may allow thedistal end24 of thepusher member14 to be disposed at a location within or external to thedistal tip18 of theouter catheter12.
• FIG. 7(b) shows theclip2, still in its stressed state, puncturing the flap oftissue40. The nature of the material of theclip2 is such that theclip2 remains in the stressed state as thetines4 pierce the flap oftissue40. After theclip2 has passed through the flap oftissue40, theclip2 begins its transformation from the stressed state to the relaxed state shown, for example, inFIG. 2.FIG. 7(c) shows theclip2 after it has passed into the relaxed state. In this embodiment, thetips8 of thetines4 have inflected back in the direction of the retainingend6 of theclip2. In doing so, thetips8 of theclip2 preferably engage with theseptum wall38 on opposing sides of the flap oftissue40. While it is preferable that bothtips8 be engaged with theseptum wall38 to properly close theopening42, it may still be possible to close theopening42 if only one of thetips8 engages with theseptum wall38.
• As best seen inFIG. 6, in which a perspective detail view of the region of theseptum wall38 having theseptal defect30 is shown, theopening42 between the first andsecond chambers34,36 has been eliminated by the placement of theclip2 in the flap oftissue40. By engaging with theseptum wall38, thetips8 of theclip2 may prevent the flap oftissue40 from moving proximate to theseptum wall38 in the first chamber34 (as is shown inFIG. 7(a)).
• FIGS. 8 and 9 show an alternative preferred embodiment of theclip2 wherein theclip2 has fourtines4 as opposed to the twotines4 shown inFIGS. 1-7(c),10, and11.FIG. 8 shows theclip2 in a stressed state whileFIG. 9 shows theclip2 in a relaxed state. Theadditional tines4 may increase the chances that one ormore tines4 will properly be secured to theseptum wall38 upon deployment. Whileclips2 having two and fourtines4 have been specifically disclosed herein, it should be understood that theclip2 may have any number oftines4 in excess of one, including even and odd numbers oftines4.
• It will be appreciated by those skilled in the art that the procedure described herein may be monitored in a variety of ways. For example, thedelivery apparatus10 may include an imaging device50 (FIGS. 5 and 6), such as an angioscope or other fiber optic device, intravascular ultrasound (“IVUS”) device, and the like (not shown). The device may be provided on thedistal end16 of theouter catheter12, e.g., attached to or adjacent thedistal tip18 or advanceable from a lumen (not shown) therein. In a further alternative, external imaging may be used, either alone or in conjunction with direct visualization. For example, theclip2, theouter catheter12, and/or thepusher member14 may include radiopaque markers (not shown) at predetermined locations that may be observed using fluoroscopy and the like.
• FIGS. 10 and 11 illustrate a preferred embodiment of theclip2, wherein in its relaxed state (shown inFIG. 11), thetines4 of theclip2 lie substantially flat against theseptum wall38. This embodiment may be preferred for several reasons. First, a larger portion of thetines4 may be in contact with theseptum wall38, giving the clip2 a more secure hold to the flap(s) oftissue40. Second, since at least a portion of thetines4 lie substantially flat against theseptum wall38, less surface area of theclip2 may be exposed to the patient's blood. Typically, a patient that receives aclip2 may be administered anti-coagulant drugs to counteract the clotting of platelets on the surface of theclip2. By reducing the amount of surface area of theclip2 that is exposed to the blood, clotting problems may be reduced.FIG. 11 shows a cross-sectional view of theseptum wall38 with theclip2 in its relaxed state. Preferably, theclip2 is designed such that thetines4 of theclip2 lie substantially flat against theseptum wall38 on either side of theseptal defect30.
• FIGS. 10 and 11 further illustrate theseptum wall38 containing aseptal defect30 in which the defect is a hole-type structure52 that may pass laterally through theseptum wall38 of aheart32. In this regard, theseptal defect30 is similar to two overlapping flaps oftissue40. This type ofseptal defect30 may be seen, for example, in patients having a PFO. Theclip2 may be delivered in a similar way to the method described above. Specifically, theclip2 may puncture the two overlapping flaps oftissue40 while theclip2 is in its stressed state and, upon relaxation, at least a portion of the hole-type structure52 may collapse, thereby preventing the flow of blood across theseptum wall38.
• In yet another embodiment of the invention, theclip2 may have only asingle tine4. In its biased state, theclip2 is substantially linear, as is shown, for example, inFIG. 12. Theclip2 is deployed by piercing one or more flap(s) oftissue40 such that a portion of theclip2 is one side of aseptum wall38 and the remaining portion is on the opposing side of theseptum wall38. Both “halves” of theclip2 then bend from a stressed state to a relaxed state to close the septal defect. Theclip2 in its relaxed state may take the shape of a “U” or “V” (shown, for example, inFIG. 12), or even an “S” (shown inFIG. 13).FIG. 14 shows yet another embodiment of aclip2 having asingle tine4. In this embodiment, the retainingend6 of theclip2 includes a head7 that prevents theclip2 from passing completely through theseptum wall38. In this regard, theclip2, in its relaxed state, takes the shape of an “L”. During deployment of thisclip2, thetine4 is preferably advanced through theseptum wall38 until the head7 prevents further advancement of theclip2.
• While the invention is susceptible to various modifications, and alternative forms, specific examples thereof have been shown in the drawings and are herein described in detail. It should be understood, however, that the invention is not to be limited to the particular forms or methods disclosed, but to the contrary, the invention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the appended claims.

Claims (20)

1. An apparatus for closing a septal defect, comprising:

a clip formed from an elastic material having at least two penetrating tines and an opposing retaining end, the clip being biased so as to project the at least two penetrating tines distal to the opposing retaining end, wherein when the bias is removed, the at least two penetrating tines move laterally apart from one another.

2. The apparatus ofclaim 1, wherein the clip is formed from a superelastic material.

3. The apparatus ofclaim 1, wherein the clip, in a stressed state, has a V shape.

4. The apparatus ofclaim 1, wherein the clip, in a relaxed state, has a W shape.

5. The apparatus ofclaim 1, wherein the clip, in a stressed state, has a U shape.

6. The apparatus ofclaim 1, further comprising:

a tubular member comprising proximal and distal ends and a lumen therebetween, the distal end having a size for insertion into a blood vessel, the clip being carried within the lumen such that the penetrating tines are disposed distally to the retaining end; and

a pusher member slidably disposed within the lumen, the pusher member comprising a distal end disposed proximate the retaining end of the clip, the pusher member being moveable axially relative to the tubular member for ejecting the clip distally from the lumen.

7. The apparatus ofclaim 6, further comprising an actuator on the proximal end of the tubular member for advancing the pusher member relative to the tubular member.

8. The apparatus ofclaim 6, further comprising at least one axially disposed clip-retaining groove located in an inner surface of the tubular member.

9. The apparatus ofclaim 6, further comprising a notch located in the distal end of the pusher member for engaging the retaining end of the clip.

10. The apparatus ofclaim 6, further comprising an imaging device comprising an imaging element associated with the distal end of the tubular member.

11. The apparatus ofclaim 10, wherein the imaging device comprises an elongate member comprising a distal end having a size for introduction into a body lumen.

12. A method of closing a septal defect within a patient's heart comprising the steps of:

providing a clip having at least two penetrating tines and an opposing retaining end;

advancing the clip, in a biased state, through the patient's vasculature until the clip is disposed within the first chamber of the heart adjacent to the septal opening;

directing the at least two penetrating tines through a flap of tissue to expose the at least two penetrating tines to the second chamber of the heart;

moving the tines of the clip in laterally opposing directions so as to bring the flap of tissue into engagement with the septum wall to at least partially close the septal opening.

13. The method according toclaim 12, wherein the tines of the clip are moved by removing the biasing force so as to permit the clip to transition to a relaxed state.

14. The method according toclaim 13, wherein the clip is disposed within a distal end of a delivery apparatus comprising a catheter and a pusher member slidably coupled to one another, and wherein the step of advancing the clip comprises advancing the distal end of the delivery apparatus into the first chamber until the distal end is disposed adjacent to the septal defect.

15. The method ofclaim 14, wherein the step of directing the first end of the clip through the flap of tissue comprises advancing the pusher member distally relative to the catheter, thereby ejecting the clip from within the delivery apparatus.

16. The method ofclaim 15, wherein the biasing force is removed by ejecting the clip from the delivery apparatus.

17. The apparatus ofclaim 1, wherein the clip is formed from NITINOL.

18. The method ofclaim 12, further comprising the step of imaging a portion of the heart.

19. An apparatus for closing a septal defect, comprising:

A clip formed from an elastic material having a single penetrating tine and an opposing retaining end, the clip being biased so as to project the single tine distal to the opposing retaining end, wherein when the bias is removed, the clip transforms into geometric shape selected from the group consisting of “V”, “U”, “S”, and “L”.

20. The apparatus ofclaim 19, further comprising a head attached to the retaining end of the clip.

Images