US20190159882A1 - Framed biodegradable yarn structure and method - Google Patents

Abstract

The techniques of this disclosure generally relate to a prosthesis including framed biodegradable yarn graft material having a frame and biodegradable yarns combined with the frame. The biodegradable yarns seal tissue integration openings within the frame. The frame provides long term mechanical strength while the biodegradable yarns provide acute strength and impermeability to prevent endoleaks. As the biodegradable yarns degrade, the drop in textile density creates tissue integration openings, through which tissue grows. The integrate of tissue into the framed biodegradable yarn graft material provides biological fixation of the prosthesis in vessels and prevents endoleaks and migration of the prosthesis.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application claims the benefit of U.S. Provisional Application No. 62/591,601, filed on Nov. 28, 2017, entitled “ADVANCED GRAFT MATERIALS FOR ENDOVASCULAR APPLICATIONS” of Borglin et al., which is incorporated herein by reference in its entirety.
FIELD
• The present technology is generally related to an intra-vascular device and method. More particularly, the present application relates to a device for treatment of intra-vascular diseases.
BACKGROUND
• A conventional stent-graft typically includes a radially expandable reinforcement structure, formed from a plurality of annular stent rings, and a cylindrically shaped layer of graft material defining a lumen to which the stent rings are coupled. Stent-grafts are well known for use in tubular shaped human vessels.
• To illustrate, endovascular aneurysmal exclusion is a method of using a stent-graft to exclude pressurized fluid flow from the interior of an aneurysm, thereby reducing the risk of rupture of the aneurysm and the associated invasive surgical intervention. The graft material of traditional stent-grafts is extremely hydrophobic and presents a hostile environment for the recruitment and proliferation of cells. The inability of tissue to integrate into the graft material prevents the biological fixation of the stent-graft in vessels and makes the stent-graft susceptible to endoleaks and migration.
SUMMARY
• The techniques of this disclosure generally relate to a prosthesis including framed biodegradable yarn graft material having a frame and biodegradable yarns combined with the frame. The biodegradable yarns seal tissue integration openings within the frame. The frame provides long term mechanical strength while the biodegradable yarns provide acute strength and impermeability to prevent endoleaks. As the biodegradable yarns degrade, the drop in textile density creates tissue integration openings, through which tissue grows. The integrate of tissue into the framed biodegradable yarn graft material provides biological fixation of the prosthesis in vessels and prevents endoleaks and migration of the prosthesis.
• In one aspect, the present disclosure provides a frame and biodegradable yarns combined with the frame.
• In another aspect, the disclosure provides a prosthesis including a proximal seal zone including a framed biodegradable yarn graft material and an exclusion zone including permanent and impermeable graft material.
• In yet another aspect, the disclosure provides a method including forming a prosthesis by forming a framed biodegradable yarn graft material by combining biodegradable yarns with a frame.
• The details of one or more aspects of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the techniques described in this disclosure will be apparent from the description and drawings, and from the claims.
BRIEF DESCRIPTION OF DRAWINGS
• FIG. 1 is a perspective view of a framed biodegradable yarn stent-graft in accordance with one embodiment.
• FIG. 2 is an enlarged perspective view of a region II of the stent-graft ofFIG. 1 in accordance with one embodiment.
• FIG. 3 is a plan view of the region II of the stent-graft ofFIG. 1 in accordance with one embodiment.
• FIG. 4 is a cross-sectional view of a graft material along the line IV-IV ofFIG. 3 upon initial deployment on a vessel wall in accordance with one embodiment.
• FIG. 5 is an enlarged plan view of the section of the graft material ofFIG. 3 after dissolution of biodegradable yarns in accordance with one embodiment.
• FIG. 6 is a cross-sectional view of the graft material along the line VI-VI ofFIG. 5 after a period of time after deployment on the vessel wall in accordance with one embodiment.
• FIG. 7 is a cross-sectional view of a vessel assembly including the stent-graft ofFIG. 1 after initial deployment within a vessel having a dissection in accordance with one embodiment.
• FIG. 8 is an enlarged cross-sectional view of a region VIII of the vessel assembly ofFIG. 7 in accordance with one embodiment.
• FIG. 9 is a cross-sectional view of the region VIII of the vessel assembly ofFIG. 7 after a period of time after deployment of the stent-graft within the vessel in accordance with one embodiment.
• FIG. 10 is a cross-sectional view of a vessel assembly including a stent-graft in accordance with another embodiment.
DETAILED DESCRIPTION
• FIG. 1 is a perspective view of a framed biodegradable yarn stent-graft100 in accordance with one embodiment. Referring now toFIG. 1, stent-graft100, sometimes called a prosthesis, includes a framed biodegradableyarn graft material102 and one or morestent rings104 coupled tograft material102. Illustratively,stent rings104 are self-expanding stent rings, e.g., nickel titanium alloy (NiTi), sometimes called Nitinol, or self-expanding members. The inclusion ofstent rings104 is optional and in oneembodiment stent rings104 are not included. In another embodiment,stent rings104 are balloon expandable stents.
• In accordance with this embodiment,graft material102 includes aproximal opening106 at aproximal end108 ofgraft material102 and adistal opening110 at adistal end112 ofgraft material102.
• Further, stent-graft100 includes a longitudinal axisL. A lumen114 is defined bygraft material102, and generally by stent-graft100.Lumen114 extends generally parallel to longitudinal axis L and betweenproximal opening106 anddistal opening110 of stent-graft100.
• As used herein, the proximal end of a prosthesis such as stent-graft100 is the end closest to the heart via the path of blood flow whereas the distal end is the end furthest away from the heart during deployment. In contrast and of note, the distal end of the catheter is usually identified to the end that is farthest from the operator/handle while the proximal end of the catheter is the end nearest the operator/handle.
• For purposes of clarity of discussion, as used herein, the distal end of the catheter is the end that is farthest from the operator (the end furthest from the handle) while the distal end of stent-graft100 is the end nearest the operator (the end nearest the handle), i.e., the distal end of the catheter and the proximal end of stent-graft100 are the ends furthest from the handle while the proximal end of the catheter and the distal end of stent-graft100 are the ends nearest the handle. However, those of skill in the art will understand that depending upon the access location, stent-graft100 and the delivery system descriptions may be consistent or opposite in actual usage.
• Graft material102 is cylindrical having a substantially uniform diameter. However, in other embodiments,graft material102 varies in diameter, is bifurcated atdistal end112, and/or is a multi-limbed device for branching applications.Graft material102 includes aninner surface116 and an oppositeouter surface118, e.g., cylindrical surfaces in accordance with this embodiment.
• FIG. 2 is an enlarged perspective view of the region II of stent-graft100 ofFIG. 1 in accordance with one embodiment.FIG. 3 is a plan view of the region II of stent-graft100 ofFIG. 1 in accordance with one embodiment. Referring now toFIGS. 1, 2, and 3 together,graft material102 includes aframe220 andbiodegradable yarns222.
• In one embodiment,frame220 is permanent, e.g., will last in the human body for an extended period of time such as 10 years or more.Frame220 is sometimes called non-absorbable, and persistent. In one embodiment,frame220 is polyester terephthalate (PET), expanded polyester terephthalate (ePET), nickel titanium alloy (NiTi), or other permanent graft material or textile.
• In contrast toframe220,biodegradable yarns222 are a biodegradable material, i.e., are biodegradable. As used herein, biodegradable means capable of being broken down in the human body, e.g., through contact with fluid such as blood and/or tissue such as a vessel wall. Examples ofbiodegradable yarns222 include polymer polyglycolic-lactic acid (PLGA), poly(glycerol sebacate) (PGS), Polyglycolic acid (PGA), or Poly Lactic Acid (PLA).
• Frame220 provides long term mechanical strength whilebiodegradable yarns222 provide acute strength and impermeability to prevent endoleaks. As discussed in further detail below, asbiodegradable yarns222 degrade, the drop in textile density creates tissue integration openings, sometimes called ingress channels, through which tissue grows.
• In accordance with this embodiment,frame220 includespermanent yarns224.Biodegradable yarns222 are combined withpermanent yarns224 and more generally withframe220 to formgraft material102. Generally,graft material102 includespermanent yarns224 andbiodegradable yarns222 which are woven, knitted, sewn, or otherwise combined to creategraft material102. In one embodiment, yarns are long string like members, sometimes called threads, fibers, filaments, or cylindrical structures.
• Biodegradable yarns222 are illustrated as including a plurality of verticalbiodegradable yarns222V and a plurality of horizontalbiodegradable yarns222H. Similarly,permanent yarns224 illustrated as including a plurality of verticalpermanent yarns224V and a plurality of horizontalpermanent yarns224H.Yarns222V,222H,224V,224H are interlaced with one another.
• In accordance with this embodiment, eachyarn222,224 is interlaced with theother yarns222,224 in a weaving pattern, e.g., an over under pattern. For example, two adjacent horizontalpermanent yarns224H are interlaced, e.g., in an over under or weaving pattern, with two adjacent vertical horizontalpermanent yarns224V in the view ofFIGS. 2 and 3. This pattern is repeated to formframe220.
• Similarly, eachbiodegradable yarn222 interlaced withframe220 and the otherbiodegradable yarns222 in a weaving pattern. In accordance with this embodiment, there is a ratio of threebiodegradable yarns222 to eachpermanent yarn224, e.g., a 3/1 ratio. More generally, there are morebiodegradable yarns222 thanpermanent yarns224. In addition, a diameter D1 ofbiodegradable yarns222 is less than a diameter D2 ofpermanent yarns224.
• However, depending upon the application, the size ofyarns222,224 and the weave pattern can be different than that illustrated inFIGS. 2-3. For example, the ratio ofbiodegradable yarns222 topermanent yarns224 is more or less than 3/1 in other embodiments. Further, diameter D1 ofbiodegradable yarns222 is equal to or greater than diameter D2 ofpermanent yarns224 in other embodiments.
• The illustrated arrangement ofyarns222,224, e.g., woven, is illustrative only and in light of this disclosure those of skill in the art will understand thatyarns222,224 can be combined in any one of a number of different fashions to formgraft material102. For example,yarns222,224 are woven, knitted, sewn, or otherwise combined to creategraft material102.
• Atissue integration opening226, e.g., a space, is defined by the two adjacent horizontalpermanent yarns224H and the two adjacent verticalpermanent yarns224V illustrated inFIGS. 2 and 3. More particularly,tissue integration opening226 is defined by two adjacent verticalpermanent yarns224V and two adjacent horizontalpermanent yarns224H. The othertissue integration openings226 ingraft material102 are defined in a similar manner.
• Tissue integration openings226 are sealed bybiodegradable yarns222. In accordance with the embodiment illustrated inFIGS. 2 and 3,tissue integration openings226 are sealed by three horizontalbiodegradable yarns222H interlaced with three verticalbiodegradable yarns222V. Generally,tissue integration openings226 inframe220 are sealed bybiodegradable yarns222.
• Astissue integration openings226 are sealed bybiodegradable yarns222,graft material102 is essentially impermeable. In one embodiment, there aresmall pores228, sometimes calledinterstices228, betweenyarns222,224.Pores228 are typically formed due to the overlapping nature ofyarns222,224 and the inability to makeyarns222,224 completely flush with one another along the entire length ofyarns222,224. However, pores228 are sufficiently small that fluid leakage throughpores228 is negligible. Althoughpores228 are illustrated, in other embodiments,graft material102 has an absence of pores and is completely impermeable.
• Over time,biodegradable yarns222 biodegrade and dissolve. This removesbiodegradable yarns222 fromtissue integration openings226 offrame220, sometimes called openstissue integration openings226. Once opened,tissue integration openings226 provide ingress channels ingraft material102 to encourage tissue integration therein. An example of the dissolution ofbiodegradable yarns222 and tissue integration intotissue integration openings226 is set forth below in reference toFIGS. 3-6.
• FIG. 4 is a cross-sectional view ofgraft material102 along the line IV-IV ofFIG. 3 upon initial deployment on avessel wall402 in accordance with one embodiment.
• Referring now ofFIGS. 1, 3 and 4 together, stent-graft100 is deployed within a vessel including thevessel wall402. For example, stent-graft100 is deployed to treat an abdominal aortic aneurysm, a thoracic aortic aneurysm, a dissection, or other medical condition.
• Upon initial deployment,biodegradable yarns222 remain in their original form and are undissolved. As discussed above, prior to dissolution ofbiodegradable yarns222,graft material102 is essentially impermeable. This, in turn, minimizes and essentially eliminates leaks throughgraft material102, e.g., type IV endoleaks.
• Paying particular attention toFIGS. 1 and 4 together, stent-graft100contacts vessel wall402. Accordingly, fluid flows though stent-graft100, i.e., throughlumen114. Due to the impermeability of stent-graft100,vessel wall402 including any defect associated therewith, e.g., a dissection or aneurysm, are excluding from the pressurized fluid flow through stent-graft100.
• FIG. 5 is an enlarged plan view of the section ofgraft material102 ofFIG. 3 after dissolution ofbiodegradable yarns222 in accordance with one embodiment.FIG. 6 is a cross-sectional view ofgraft material102 along the line VI-VI ofFIG. 5 after a period of time after deployment onvessel wall402 in accordance with one embodiment.
• Referring now ofFIGS. 1, 5-6 together, after a period of time, biodegradable yarns222 (seeFIGS. 3-4) dissolve. However,frame220 includingpermanent yarns224 remain in the same configuration as when initially deployed or approximately there so.
• Biodegradable yarns222 slowly dissolve over a period of time. Asbiodegradable yarns222 dissolve,tissue integration openings226 are uncovered bybiodegradable yarns222 and opened.
• Over time,biodegradable yarns222 are replaced withtissue604 fromvessel wall402 that integrates within and throughtissue integration openings226 as illustrated inFIG. 6.Tissue604 encasesframe220 includingpermanent yarns224 and fillstissue integration openings226 preventing leakage throughtissue integration openings226 in accordance with this embodiment. The integrate oftissue604 intograft material102 provides biological fixation of stent-graft100 in vessels and prevents endoleaks and migration of stent-graft100. Generally, stent-graft100 becomes integrated with the vessel includingvessel wall402.
• As discussed below in reference toFIGS. 7-10, stent-graft100 is used to cover and treat various defects in a vessel.
• FIG. 7 is a cross-sectional view of avessel assembly700 including stent-graft100 ofFIG. 1 after initial deployment within avessel702 having a dissection in accordance with one embodiment.FIG. 8 is an enlarged cross-sectional view of a region VIII ofvessel assembly700 ofFIG. 7 in accordance with one embodiment. InFIG. 7, stent-ring104 is not illustrated for simplicity.
• Referring toFIGS. 1, 7-8 together, a dissection is a condition in which aninner layer706 ofvessel702 tears to have adissection opening708. Fluid, e.g., blood, flows throughdissection opening708 and into afalse lumen710 betweeninner layer706 and one or more otherouter layers712 ofvessel702. Left untreated,false lumen710 can ruptureouter layers712 ofvessel702 leading to serious complications and often death.
• In accordance with this embodiment, stent-graft100 is deployed to cover and excludedissection opening708. As discussed above, when initially deployed, stent-graft100 is impermeable thus sealingdissection opening708 and preventing pressurized fluid flow throughfalse lumen710.
• FIG. 9 is a cross-sectional view of region VIII ofvessel assembly700 ofFIG. 7 after a period of time after deployment of stent-graft100 withinvessel702 in accordance with one embodiment. Referring now toFIGS. 1, 7-9, due to the covering and exclusion of the dissection with stent-graft100, dissection opening708 heals and closes andfalse lumen710 collapses. At the same time,biodegradable yarns222 dissolve allowingtissue904 integration intotissue integration openings226 of stent-graft100 including betweenpermanent yarns224 offrame220.
• FIG. 10 is a cross-sectional view of avessel assembly1002 including a stent-graft1000 in accordance with another embodiment. Stent-graft1000 ofFIG. 10 is similar to stent-graft100 ofFIG. 1 and only the significant differences are discussed below. Stent-graft1000 is illustrated with an absence of stent-rings104 for simplicity but includes stent-rings104 in other embodiments.
• In accordance with this embodiment, a graft material1001 and more generally stent-graft1000 includes at least threezones1004,1006,1008 in accordance with this embodiment.Proximal seal zone1004 extends fromproximal end108 toexclusion zone1006.Exclusion zone1006 extends fromproximal seal zone1004 todistal seal zone1008.Distal seal zone1008 extends fromexclusion zone1006 todistal end112.
• Proximal seal zone1004 anddistal seal zone1008 include framed biodegradableyarn graft material102 similar to that discussed. More particularly, onlyproximal seal zone1004 anddistal seal zone1008 include framed biodegradableyarn graft material102 havingframe220 andbiodegradable yarns222.
• However,exclusion zone1006 is formed of non-biodegradable material, is permanent, and impermeable. For example, in accordance with various embodiments,exclusion zone1006 is graft material made of polyester terephthalate (PET), ePET, or other similar graft material or textile.
• Stent-graft1000 is deployed into avessel1010 to exclude ananeurysm1012 using any one of a number of techniques well known to those of skill in the art. More particularly,proximal seal zone1004 anddistal seal zone1008 are deployed proximally and distally toaneurysm1012, respectively.
• Proximal seal zone1004 anddistal seal zone1008 directly contact avessel wall1014 ofvessel1010. Over time,biodegradable yarns222 ofproximal seal zone1004 anddistal seal zone1008 dissolve. This allows tissue integration intoproximal seal zone1004 anddistal seal zone1008 of stent-graft1000 in a manner similar to that discussed above. This, in turn, prevents leakage aroundproximal seal zone1004 anddistal seal zone1008 and migration of stent-graft1000.
• Further,exclusion zone1006 is deployed overaneurysm1012, i.e., to excludeaneurysm1012. Accordingly, blood flows throughexclusion zone1006 and more generally through stent-graft1000 thus excludinganeurysm1012. Asexclusion zone1006 may not contactvessel wall1014 butspan aneurysm1012,exclusion zone1006 does not include biodegradable material such thattissue integration openings226, e.g., seetissue integration openings226 ofFIGS. 5-6, are not created in stent-graft1000 inexclusion zone1006.
• It should be understood that various aspects disclosed herein may be combined in different combinations than the combinations specifically presented in the description and accompanying drawings. It should also be understood that, depending on the example, certain acts or events of any of the processes or methods described herein may be performed in a different sequence, may be added, merged, or left out altogether (e.g., all described acts or events may not be necessary to carry out the techniques). In addition, while certain aspects of this disclosure are described as being performed by a single module or unit for purposes of clarity, it should be understood that the techniques of this disclosure may be performed by a combination of units or modules associated with, for example, a medical device.
• In one or more examples, the described techniques may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions or code on a computer-readable medium and executed by a hardware-based processing unit. Computer-readable media may include non-transitory computer-readable media, which corresponds to a tangible medium such as data storage media (e.g., RAM, ROM, EEPROM, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer).
• Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general purpose microprocessors, application specific integrated circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuitry. Accordingly, the term “processor” as used herein may refer to any of the foregoing structure or any other physical structure suitable for implementation of the described techniques. Also, the techniques could be fully implemented in one or more circuits or logic elements.

Claims (20)

What is claimed is:

1. A prosthesis comprising:

a frame; and

biodegradable yarns combined with the frame.

2. The prosthesis ofclaim 1 where the frame comprises permanent yarns.

3. The prosthesis ofclaim 2 wherein a diameter of the permanent yarns is greater than a diameter of the biodegradable yarns.

4. The prosthesis ofclaim 2 wherein there are more biodegradable yarns than permanent yarns.

5. The prosthesis ofclaim 1 wherein the frame comprises tissue integration openings.

6. The prosthesis ofclaim 5 wherein the tissue integration openings are sealed by the biodegradable yarns.

7. The prosthesis ofclaim 5 wherein each of the tissue integration openings are defined by two adjacent vertical permanent yarns of the frame and two adjacent horizontal permanent yarns of the frame.

8. The prosthesis ofclaim 1 wherein the frame and the biodegradable yarns are woven together.

9. The prosthesis ofclaim 1 further comprising a framed biodegradable yarn graft material comprising the frame and the biodegradable yarns.

10. The prosthesis ofclaim 9 further comprising at least one stent ring coupled to the framed biodegradable yarn graft material.

11. A prosthesis comprising:

a proximal seal zone comprising a framed biodegradable yarn graft material; and

an exclusion zone comprising permanent and impermeable graft material.

12. The prosthesis ofclaim 11 further comprising:

a distal seal zone comprising the framed biodegradable yarn graft material.

13. The prosthesis ofclaim 12 wherein the exclusion zone extends from the proximal seal zone to the distal seal zone.

14. The prosthesis ofclaim 11 wherein the framed biodegradable yarn graft material comprises permanent yarns combined with biodegradable yarns.

15. The prosthesis ofclaim 14 wherein the permanent yarns are woven with the biodegradable yarns.

16. A method comprising:

forming a prosthesis comprising:

forming a framed biodegradable yarn graft material by combining biodegradable yarns with a frame.

17. The method ofclaim 16 further comprising sealing tissue integration openings within the frame with the biodegradable yarns.

18. The method ofclaim 17 further comprising deploying the prosthesis within a vessel, wherein the framed biodegradable yarn graft material contacts a vessel wall of the vessel.

19. The method ofclaim 18 wherein the biodegradable yarns biodegrade opening the tissue integration openings.

20. The method ofclaim 19 wherein tissue from the vessel wall fills the tissue integration openings and encases the frame.

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