US20070198060A1 - Device with biological tissue scaffold for percutaneous closure of an intracardiac defect and methods thereof - Google Patents

Abstract

The invention provides an intracardiac occluder, which has biological tissue scaffolds as occlusion shells, for the percutaneous transluminal treatment of an intracardiac defect. The intracardiac occluder includes a proximal support structure supporting the proximal occlusion shell and a distal support structure supporting the distal occlusion shell. In one embodiment, biological tissue derived from the tunica submucosa layer of the porcine small intestine forms the occlusion shells.

Description

CROSS-REFERENCE TO RELATED APPLICATION
• This application incorporates by reference, and claims priority to and the benefit of, U.S. provisional application Ser. No. 60/385,274, which was filed Jun. 3, 2002.
TECHNICAL FIELD
• The invention generally relates to devices and related methods for treating intracardiac defects. More particularly, the invention provides an intracardiac occluder with a biological tissue scaffold, and related methods, for the percutaneous closure of intracardiac defects.
BACKGROUND
• The human heart is divided into four compartments or chambers. The left and right atria are located in the upper portion of the heart and the left and right ventricles are located in the lower portion of the heart. The left and right atria are separated from each other by a muscular wall, the intraatrial septum, while the ventricles are separated by the intraventricular septum.
• Either congenitally or by acquisition, abnormal openings, holes, or shunts can occur between the chambers of the heart or the great vessels, causing blood to flow therethrough. Such deformities are usually congenital and originate during fetal life when the heart forms from a folded tube into a four chambered, two unit system. The deformities result from the incomplete formation of the septum, or muscular wall, between the chambers of the heart and can cause significant problems. Ultimately, the deformities add strain on the heart, which may result in heart failure if they are not corrected.
• One such deformity or defect, a patent foramen ovale, is a persistent, one-way, usually flap-like opening in the wall between the right atrium and left atrium of the heart. Since left atrial pressure is normally higher than right atrial pressure, the flap typically stays closed. Under certain conditions, however, right atrial pressure exceeds left atrial pressure, creating the possibility for right to left shunting that can allow blood clots to enter the systemic circulation. This is particularly worrisome to patients who are prone to forming venous thrombus, such as those with deep vein thrombosis or clotting abnormalities.
• Nonsurgical (i.e., percutaneous) closure of patent foramen ovales, as well as similar intracardiac defects such as atrial septal defects, ventricular septal defects, and left atrial appendages, is possible using a variety of mechanical closure devices. These devices, which allow patients to avoid the potential side effects often associated with standard anticoagulation therapies, typically consist of a metallic structural framework that is combined with a synthetic scaffold material. The synthetic scaffold material encourages ingrowth and encapsulation of the device. Current devices typically utilize a polyester fabric, expanded polytetrafluoroethylene (ePTFE), Ivalon®, or a metal mesh as the synthetic scaffold material. Such devices suffer, however, from several disadvantages, including thrombus formation, chronic inflammation, and residual leaks.
SUMMARY OF THE INVENTION
• The present invention provides a device for occluding intracardiac defects. The device includes a biological tissue scaffold, as opposed to a synthetic scaffold (e.g., a polyester fabric, ePTFE, Ivalon®, or a metal mesh) as presently used by devices known in the art. In a preferred embodiment, the biological tissue scaffold is fabricated from collagen. In one embodiment, a specific type of biological tissue, derived from the tunica submucosa layer of the porcine small intestine, forms the tissue scaffold. As a result of this structure, the aforementioned disadvantages associated with the devices known in the art are minimized or eliminated.
• In one aspect, the invention provides an intracardiac occluder for percutaneous transluminal treatment of an intracardiac defect. The intracardiac occluder includes a proximal support structure supporting a proximal occlusion shell and a distal support structure supporting a distal occlusion shell. The distal support structure is coupled to the proximal support structure and at least one of the occlusion shells includes a biological tissue scaffold.
• Various embodiments of this aspect of the invention include the following features. The biological tissue scaffold may be a purified bioengineered type 1 collagen that may be derived from a tunica submucosa layer of a porcine small intestine. Further, in one embodiment, at least one of the support structures includes a corrosion resistant metal. Alternatively, at least one of the support structures includes a bioresorbable polymer or a biodegradable polymer. In yet another embodiment, the proximal support structure includes a plurality of outwardly extending proximal arms and the distal support structure includes a plurality of outwardly extending distal arms.
• In another aspect, the invention provides a method for percutaneous transluminal treatment of an intracardiac defect in a patient. The method includes providing an intracardiac occluder as described above, positioning the intracardiac occluder proximate the intracardiac defect, and engaging the intracardiac defect with the intracardiac occluder to substantially occlude the intracardiac defect.
• In one embodiment of this aspect of the invention, the intracardiac defect is engaged by positioning the proximal occlusion shell and the distal occlusion shell on different sides of the intracardiac defect. The intracardiac defect may be, for example, a patent foramen ovale, an atrial septal defect, a ventricular septal defect, or a left atrial appendage.
• In yet another aspect, the invention provides a method for making an intracardiac occluder for the percutaneous transluminal treatment of an intracardiac defect. The method includes providing an overall support structure and first and second biological tissue scaffolds. The overall support structure includes a proximal support structure and a distal support structure. The method further includes coupling the first biological tissue scaffold to the proximal support structure and coupling the second biological tissue scaffold to the distal support structure. In various embodiments of this aspect of the invention, the biological tissue scaffolds are sewn, laminated, or glued to the support structures.
• The foregoing and other objects, aspects, features, and advantages of the invention will become more apparent from the following description and from the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
• In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention.
• FIG. 1 is a cutaway view of a heart illustrating an intracardiac defect.
• FIG. 2A is a top plan view of an intracardiac occluder according to an illustrative embodiment of the invention.
• FIG. 2B is a cross-sectional view of the illustrative intracardiac occluder ofFIG. 2A.
• FIG. 3A is a top plan view of an intracardiac occluder according to another illustrative embodiment of the invention.
• FIG. 3B is a side view of the illustrative intracardiac occluder ofFIG. 3A.
• FIG. 4 is a perspective view of an intracardiac occluder according to another illustrative embodiment of the invention.
• FIGS. 5A-5E illustrate the stages, according to an illustrative embodiment of the invention, for delivering an intracardiac occluder to an anatomical site in the body of a patient.
• FIG. 6A illustrates the results from occluding an intracardiac defect with an intracardiac occcluder known in the art, 30-days after delivery of the intracardiac occluder.
• FIG. 6B illustrates the results from occluding an intracardiac defect with an intracardiac occluder according to the invention, 30-days after delivery of the intracardiac occluder.
• FIG. 7A illustrates the results from occluding an intracardiac defect with an intracardiac occcluder known in the art, 90-days after delivery of the intracardiac occluder.
• FIG. 7B illustrates the results from occluding an intracardiac defect with an intracardiac occcluder according to the invention, 90-days after delivery of the intracardiac occluder.
DETAILED DESCRIPTION OF THE INVENTION
• The present invention provides an intracardiac occluder for the repair of intracardiac defects, such as, for example, a patent foramen ovale, an atrial septal defect, a ventricular septal defect, and left atrial appendages. The intracardiac occluder includes a structural framework and a biological tissue scaffold adhered thereto.
• FIG. 1 depicts a cutaway view of aheart100. Theheart100 includes aseptum104 that divides aright atrium108 from aleft atrium112. Theseptum104 includes aseptum primum116, aseptum secundum120, and an exemplaryintracardiac defect124, which is to be corrected by the intracardiac occluder of the present invention, between the septum primum116 and theseptum secundum120. Specifically, apatent foramen ovale124 is shown as an opening through theseptum104. Thepatent foramen ovale124 provides an undesirable fluid communication between theright atrium108 and theleft atrium112. Under certain conditions, a largepatent foramen ovale124 in theseptum104 would allow for the shunting of blood from theright atrium108 to theleft atrium112. If thepatent foramen ovale124 is not closed or obstructed in some manner, a patient is placed at high risk for an embolic stroke.
• FIG. 2A depicts anintracardiac occluder10 according to an illustrative embodiment of the invention. As shown, theintracardiac occluder10 includes a proximal occlusion shell18 (i.e., an occlusion shell that is closest to an operator of the intracardiac occluder10 (e.g., a physician)), an oppositedistal occlusion shell20, and anoverall support structure16. Theoverall support structure16 includes aproximal support structure24, for supporting theproximal occlusion shell18, and adistal support structure34, for supporting thedistal occlusion shell20. In one embodiment, both theproximal support structure24 and thedistal support structure34 include outwardly extending arms to support each of theirrespective occlusion shells18,20. As shown inFIG. 2A, for example, theproximal support structure24 includes four outwardly extendingarms26 and thedistal support structure34 similarly includes four outwardly extendingarms36. In one embodiment, each outwardly extending arm is resiliently biased as a result of including three or moreresilient coils43 radially spaced from acenter point45. Alternatively, other resilient support structures could be used. In one embodiment, the eightarms26,36 are mechanically secured together bywire52. Alternatively, other means, such as, for example, laser welding, may be used to secure the eightarms26,36 together. A cross-sectional view of theintracardiac occluder10 illustrated inFIG. 2A, showing fourarms26,36, is depicted inFIG. 2B.
• FIGS. 3A and 3B depict anintracardiac occluder10′ according to another illustrative embodiment of the invention. Anoverall support structure16′ forms a clip and includes aproximal support structure24′, for supporting aproximal occlusion shell18′, and adistal support structure34′, for supporting adistal occlusion shell20′.
• Anintracardiac occluder10″ according to yet another illustrative embodiment of the invention is illustrated inFIG. 4. Again, anoverall support structure16″ forms a clip and includes aproximal support structure24″, for supporting aproximal occlusion shell18″, and adistal support structure34″, for supporting adistal occlusion shell20″.
• Alternatively, theoverall support structure16 may assume any shape or configuration to form theproximal support structure24 and thedistal support structure34.
• In one embodiment, theoverall support structure16 is fabricated from a corrosion resistant metal, such as, for example, stainless steel, nitinol, or a nickel-cobalt-chromium-molybdenum alloy (e.g., MP35N). Alternatively, in other embodiments, theoverall support structure16 is fabricated from bioresorbable or biodegradeable polymers.
• In accordance with the present invention, theocclusion shells18,20, which are attached, as described below, to theproximal support structure24 and thedistal support structure34, respectively, are made from a biological tissue scaffold. In a preferred embodiment, the tissue scaffold is fabricated from collagen. In one embodiment, a purified (acellular) bioengineered type 1 collagen derived from the tunica submucosa layer of the porcine small intestine forms the tissue scaffold. More specifically, the tunica submucosa layer, referred to hereinafter as the Intestinal Collagen Layer (“ICL”), is separated or delaminated from the other layers of the porcine small intestine (i.e., the tunica muscularis and the tunica mucosa) by any method known in the art. For example, a Bitterling sausage casing machine is used to perform the separation. Once mechanically separated from the other layers, the ICL is, in one embodiment, chemically cleaned to remove debris and other substances, other than collagen. For example, the ICL is soaked in a buffer solution at 4 degrees Celsius without the use of any detergents, or, alternatively, in a second embodiment, it is soaked with NaOH or trypsin. Other cleaning techniques known to those skilled in the art may also be used. After cleaning, the ICL is decontaminated. Any sterilization system for use with collagen, as known in the art, may be used. For example, a dilute peracetic acid solution, gamma sterilization, or electron-beam sterilization is used to decontaminate the ICL.
• Alternatively, collagenous tissue from the fascia lata, pericardium, or dura matter of pigs or other mammalian sources, such as, for example, cows or sheep, may form the tissue scaffold. Additionally, in making theocclusion shells18,20, two or more collagen layers may be bonded together and then cross-linked to produce a biocompatible material capable of being remodeled by the host cells.
• In one embodiment, the biological tissue scaffold is non-porous and prevents the passage of fluids that are intended to be retained by the implantation of theintracardiac occluder10. In another embodiment, heparin is ionically or covalently bonded to the biological tissue scaffold to render it non-thrombogenic. In yet other embodiments, proteins or cells are applied to the biological tissue scaffold to render it non-thrombogenic and/or accelerate the healing process. Growth factors may also be applied to the biological tissue scaffold to accelerate the healing process.
• Referring again toFIG. 2A, theocclusion shells18,20 are, in one embodiment, generally square in shape. Alternatively, theocclusion shells18,20 may assume other shapes. The biological tissue scaffold forming theocclusion shells18,20 is strong and flexible. Theocclusion shells18,20 therefore easily attach to theoverall support structure16 and, as explained below, withstand sheath delivery to an anatomical site in the body of a patient. In one embodiment, theocclusion shells18,20 are sewn, as at22A,22B, with any commonly used suture material (e.g., a polyester suture) that threads through the distal ends54 of therespective arms26,36 of theproximal support structure24 and thedistal support structure34. Alternatively, theocclusion shells18,20 are laminated, glued, or attached by, for example, hooks or thermal welding to theproximal support structure24 and thedistal support structure34. In yet another embodiment, theocclusion shells18,20 are laminated to theoverall support structure16 and, additionally, to one another, such that theoverall support structure16 is encapsulated entirely within theocclusion shells18,20.
• FIGS. 5A-5E depict the stages for delivering theintracardiac occluder10, according to an illustrative embodiment of the invention, percutaneously to an anatomical site in the body of a patient. Referring toFIG. 5A, asheath190 is first inserted into theintracardiac defect186 as is typically performed by one skilled in the art. Theintracardiac occluder10 is then loaded into thelumen188 of thesheath190 and advanced throughout thelumen188 until positioned at thedistal end192 of thesheath190. Referring toFIG. 5B, thedistal occlusion shell20 of theintracardiac occluder10 is released into thedistal heart chamber191 through thedistal end192 of thesheath190. Thedistal occlusion shell20 opens automatically and resiliently. Thesheath190 is then pulled back into theproximal heart chamber193, as illustrated inFIG. 5C, to seat thedistal occlusion shell20 against thedistal wall surface194 of theintracardiac defect186. Theintracardiac defect186 is thereby occluded from the distal side. As shown inFIG. 5D, thesheath190 is then further withdrawn a sufficient distance to allow theproximal occlusion shell18 to be released from thedistal end192 of thesheath190. Theproximal occlusion shell18 opens automatically and resiliently to lie against theproximal surface196 of theintracardiac defect186, occluding theintracardiac defect186 from the proximal side. Thesheath190 is then withdrawn from the patient's body, leaving behind the openedintracardiac occluder10. As shown inFIG. 5E, theocclusion shells18,20 are positioned on either side of theintracardiac defect186 and theintracardiac occluder10 is permanently implanted within the body of the patient.
• FIGS. 6A-6B and7A-7B depict comparative 30-day and 90-day results, respectively, for the percutaneous closures of interventionally created intracardiac defects in sheep. Specifically,FIGS. 6A and 7A depict the 30-day and 90-day results, respectively, when an exemplary intracardiac occluder known in the art, whose occlusion shells were fabricated from a polyester fabric (i.e., a synthetic scaffold material), is used to occlude the intracardiac defect.FIGS. 6B and 7B depict the 30-day and 90-day results, respectively, when theintracardiac occluder10 of the instant invention, whoseocclusion shells18,20 were fabricated from ICL, is used to occlude the intracardiac defect.
• As shown, the biological tissue scaffold of theintracardiac occluder10 of the present invention increases the rate of tissue ingrowth and, consequently, decreases the time needed to completely close the intracardiac defect. Specifically, referring now toFIG. 7B, theintracardiac occluder10 of the present invention is barely visible after 90-days. The surrounding tissue ingrowth nearly completely envelopes theintracardiac occluder10. In comparison, referring now toFIG. 7A, the exemplary intracardiac occluder known in the art is still clearly visible after the same period of time.
• As also shown, theintracardiac occluder10 of the present invention naturally adheres to, and seals completely along, the edge of the intracardiac defect in a manner that is much improved from the exemplary intracardiac occluder known in the art. Additionally, in one embodiment, the biological tissue scaffold of theintracardiac occluder10 of the present invention is non-porous. As a result, theintracardiac occluder10 decreases the likelihood of fluid (e.g., blood) leakage through the opening.
• Further advantages to theintracardiac occluder10 of the present invention, in comparison to known intracardiac occluders, include decreased thrombogenicity, quicker endothelialization, superior biocompatibility, minimal foreign body reaction, decreased inmmunological and inflammatory responses, and no fibrosis.
• Variations, modifications, and other implementations of what is described herein will occur to those of ordinary skill in the art without departing from the spirit and the scope of the invention as claimed. Accordingly, the invention is to be defined not by the preceding illustrative description but instead by the spirit and scope of the following claims.

Claims (22)

1-17. (canceled)

18. An intracardiac occluder for percutaneous transvascular treatment of an intracardiac defect, comprising:

a proximal support structure supporting a proximal occlusion shell; and

a distal support structure, coupled to the proximal support structure, supporting a distal occlusion shell,

wherein at least one of the occlusion shells comprises a biological tissue scaffold comprising a bioengineered collagen, and

wherein at least one of the support structures is biodegradable or bioresorbable.

19. The occluder ofclaim 18, wherein the at least one support structure that is biodegradable or bioresorbable is fabricated from a biodegradable or bioresorbable polymer.

20. The occluder ofclaim 18, wherein the bioengineered collagen is purified bioengineered type 1 collagen.

21. The occluder ofclaim 18, wherein the bioengineered collagen is derived from tunica submucosa.

22. The occluder ofclaim 18, wherein the proximal support structure comprises a plurality of outwardly extending proximal arms and the distal support structure comprises a plurality of outwardly extending distal arms.

23. The occluder ofclaim 18, wherein heparin is ionically or covalently bound to the biological tissue scaffold.

24. The occluder ofclaim 18, wherein the biological tissue scaffold is laminated to the biodegradable or bioresorbable support structure.

25. A method for percutaneous transvascular treatment of an intracardiac defect in a patient comprising:

providing an intracardiac occluder, comprising:

a proximal support structure supporting a proximal occlusion shell; and

a distal support structure, coupled to the proximal support structure, supporting a distal occlusion shell,

wherein at least one of the occlusion shells comprises a biological tissue scaffold comprising a bioengineered collagen, and wherein at least one of the support structures is biodegradable or bioresorbable;

positioning the intracardiac occluder proximate the intracardiac defect; and

engaging the intracardiac defect with the intracardiac occluder to substantially occlude the intracardiac defect, wherein at least one of said support structures is biodegraded or bioresorbed.

26. The method ofclaim 25, wherein the at least one support structure that is biodegradable is fabricated from a biodegradable or bioresorbable polymer.

27. The method ofclaim 25, wherein engaging the intracardiac defect comprises positioning the proximal occlusion shell and the distal occlusion shell on different sides of the intracardiac defect.

28. The method ofclaim 25, wherein the intracardiac defect is a patent foramen ovale.

29. The method ofclaim 25, wherein the intracardiac defect is an atrial septal defect.

30. The method ofclaim 25, wherein the intracardiac defect is a ventricular septal defect.

31. The method ofclaim 25, wherein the intracardiac defect is a left atrial appendage.

32. The method ofclaim 25, wherein the bioengineered collagen is derived from a tunica submucosa layer of porcine small intestine.

33. A method for making an intracardiac occluder for percutaneous transluminal treatment of an intracardiac defect, comprising:

providing a support structure comprising a proximal support structure and a distal support structure wherein at least one of the proximal or distal support structure is biodegradable or bioresorbable;

providing first and second biological tissue scaffolds;

coupling the first biological tissue scaffold to the proximal support structure; and

coupling the second biological tissue scaffold to the distal support structure, wherein at least one of the first or second biological tissue scaffolds comprises a bioengineered collagen.

34. The method ofclaim 33, wherein coupling the biological tissue scaffolds comprises sewing the biological tissue scaffolds to the biodegradable or bioresorbable support structures.

35. The method ofclaim 33, wherein coupling the biological tissue scaffolds comprises laminating the biological tissue scaffolds to the biodegradable or bioresorbable support structures.

36. The method ofclaim 33, wherein coupling the biological tissue scaffolds comprises gluing the biological tissue scaffolds to the biodegradable or bioresorbable support structures.

37. The method ofclaim 33, wherein the at least one support structure that is biodegradable or bioresorbable is fabricated from a biodegradable or bioresorbable polymer.

38. An intracardiac occluder for percutaneous transvascular treatment of an intracardiac defect, comprising:

a proximal support structure comprising a plurality of arms and supporting a proximal occlusion shell, said arms each comprising a biasing point comprising three or more coils;

a distal support structure comprising a plurality of arms, the distal support structure coupled to the proximal support structure and supporting a distal occlusion shell, said arms each comprising a biasing point comprising three or more coils;

wherein at least one of the occlusion shells comprises a biological tissue scaffold comprising a bioengineered collagen, and

wherein at least one of the support structures is biodegradable or bioresorbable.

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