Endograft for treating branched vessels

An endograft comprising a proximal end and a distal end is disclosed. The endograft includes a tube of biocompatible material. The tube includes a main lumen extending longitudinally from the proximal end to the distal end, the main lumen including a proximal portion, an intermediate portion and a distal portion; a branch lumen within the intermediate portion of the main lumen; and a seam, the seam extending longitudinally beside both the branch lumen and the distal portion of the main lumen, wherein the tube includes a lateral cross-section defining a tubular wall pinched together by the seam to form a branch portion. The branch portion includes an entrance within the intermediate portion of the main lumen and an exit through the tubular wall of the main lumen.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present patent document claims the benefit of priority to Australian Patent Application No. 2016210717, filed Aug. 4, 2016, and entitled “An Endograft For Treating Branched Vessels,” the entire contents of each of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates generally to medical devices. More particularly, the present disclosure relates to endografts. In particular, the present disclosure relates to endografts deployable into the vascular system of humans or animals.

BACKGROUND

Endografts and delivery device assemblies for endografts are used in aortic intervention. They are used by vascular surgeons to treat aneurysms and to repair regions of the aorta, including the aortic arch, the thoracic aorta, the abdominal aorta and the aortic bifurcation.

Multiple stent grafts may be implanted to provide a system of interconnected stent grafts. Interconnected stent grafts can be made of fenestrated stent grafts and smaller side branch grafts.

Endografts for treating branched vessels, typically stent grafts, are intricate and take considerable time to produce. There is thus a need to provide an improved endograft for treating branched vessels.

Throughout this specification, the term “distal” with respect to a portion of the aorta, a deployment device or an endograft means the end of the aorta, deployment device or endograft further away in the direction of blood flow from the heart and the term “proximal” means the portion of the aorta, deployment device or end of the endograft nearer to the heart in the direction of blood flow. When applied to other vessels, similar terms such as caudal and cranial should be understood.

SUMMARY

According to a first aspect of the present disclosure, there is provided an endograft comprising a proximal end and a distal end, the endograft comprising a tube of biocompatible material, the tube comprising: a main lumen extending longitudinally from the proximal end to the distal end, the main lumen including a proximal portion, an intermediate portion and a distal portion; a branch lumen within the intermediate portion of the main lumen; and a seam, the seam extending longitudinally beside both the branch lumen and the distal portion of the main lumen, wherein the tube comprises a lateral cross-section defining a tubular wall pinched together by the seam to form a branch portion.

According to a second aspect of the present invention, there is provided a method of producing a endograft comprising the steps of: providing a tube of biocompatible material, the tube having a tubular wall; flattening the tube so that the tubular wall forms two substantially planar wall portions; partitioning the flattened tube by creating a longitudinal seam between the two wall portions; cutting a piece out of the tube from a position adjacent to the longitudinal seam so as to create a branch mouth into the tube; attaching a super-elastic ring to the branch mouth; and everting the tube.

DESCRIPTION OF EMBODIMENTS

One example of an endograft10according to the present disclosure is shown inFIG. 5A.FIGS. 5B, 5C and 5Dshow lateral cross-sections of the endograft ofFIG. 5Athrough section lines5B-5B,5C-5C and5D-5D respectively.

Referring toFIG. 5A, it can be seen that the endograft10consists generally of in the form of a tubular stent graft having a proximal end portion12and a distal end portion14, a tubular body15, and a lumen16extending therethrough. The endograft10may be configured to receive a fluid flow in a proximal to distal direction.

The endograft10may be any suitable length. In one example, the endograft10is a suitable length corresponding to the length of a lesion site where the endograft10is to be positioned.

The endograft10may be in a compressed or collapsed configuration (not shown) or a radially expanded configuration (shown inFIG. 5A). In the expanded configuration the endograft10may apply a radially outward force upon at least a portion of a vessel, duct, or lumen e.g., to maintain patency within a passageway.

The endograft10may be any suitable selected diameter and may be constructed or any biocompatible graft material20which is suitable for facilitating repair of an injured or diseased body vessel. The graft material20may be synthetic and/or naturally-derived material. Synthetic biocompatible polymers may include but are not limited to polyethylene terephthalate, polyurethane, nylon, polyester, high molecular weight polyethylene (such as Thoralon), polytetrafluoroethylene, or combinations thereof. The graft material20can be porous or non-porous and also may be impregnated or coated with one or more therapeutic substances. In one example, the graft material may be constructed of the commercially available material referred to as Dacron. In another example the graft material may consist of small-intestine submucosa (“SIS”) material, which may be obtained from porcine intestine. The graft material should have sufficient flexibility to allow for navigation of the vasculature and delivery to a targeted area in the body. Preferably, the graft material20is a low profile material or an ultralow profile material.

The endograft10may be supported by one or more stents21along its length. One or more stents21may be located on an interior surface23, exterior surface25, or both, of the tubular body15of the endograft10. The number of stents and their placement (internal or external) can be varied to suit the particular application or patient anatomy. Alternatively, the endograft10may be unsupported along its length such that there are no body stents located on the graft material between the proximal end portion12and distal end portion14of the endograft10.

In one example, stent21may be a Z-stent. For example, stent21may have a distal end30with a series of distal apices31and a proximal end39with a series of proximal apices33. Stent21may also have one or more elongate struts35connecting the distal apices31to the proximal apices33.

Suitable stents21for use in connection with the endograft10described herein may be self-expanding or mechanically-expandable stents or both, and may be deployed according to conventional methodology. A self-expanding stent may be manufactured from a shape-memory alloy, such as nickel titanium alloy (Nitinol). If the stent comprises a self-expanding material such as Nitinol, the stent may be heat-set into the desired expanded state whereby the stent can assume a relaxed radially expanded configuration. The stent may be made from other metals and alloys that allow the stent to return to its original expanded configuration upon deployment, such as, for example, stainless steel, cobalt-chrome alloys, amorphous metals, and/or non-metallic materials as would be recognized by one of skill in the art. Additionally or alternatively, the endograft10may be mechanically expanded, such as through the use of an expandable balloon placed within the lumen16of the endograft10and then radially outwardly expanded.

In the example shown inFIG. 5A, a plurality of zig zag stents21include a proximal end internal stent13and a distal end internal stent27. Between stents13and27they may be three external stents22,24,26.

The endograft10may be anchored to an interior wall of a body vessel, duct, or lumen proximally and/or distally to a lesion site. The endograft10ofFIG. 5Ahas a proximal end sealing region11and a distal end sealing region29. For example, the distal sealing region29of the endograft10ofFIG. 5Amay include an uncovered distal stent28. This distal stent28may include barbs (not shown) to anchor the endograft10in place.

The tubular body15of the endograft10may have a tubular wall17extending from the proximal end portion12to the distal end portion14of the endograft10. The diameter of the tubular body15may change along the length of the endograft10. In one example, the diameter at the proximal end portion12of the tubular body15is greater than the diameter at the distal end portion14of the tubular body15. A tapered transition portion45may connect the proximal end portion12and the distal end portion14.

The tubular body15may have one or more lumens extending therethrough. In one example, the tubular body15comprises a main lumen16extending longitudinally from the proximal end portion12to a distal end portion14of the endograft10.

The endograft10may include an internal branch portion37. In one example, the internal branch portion37extends from a recess or opening250in the tubular wall17into the main lumen16of the tubular body15. The branch portion37may have a proximal end52, and distal end54and a lumen36extending therethrough. In one example, the proximal end52has a larger diameter than the distal end54of the branch portion37. The branch portion37may be constructed from the same biocompatible material as the graft material20.

FIGS. 5B, 5C, and 5Dshow the endograft10at the proximal lateral100, intermediate lateral200and distal lateral300cross-sections, respectively. These lateral cross-sections can be identified as section lines5B-5B,5C-5C and5D-5D marked onFIG. 5Arespectively. As shown inFIG. 5B, the tubular wall has a main lumen16extending therethrough at the proximal lateral portion100of the endograft10. In the intermediate lateral200cross section (shown inFIG. 5C), the main lumen16and the lumen36of the internal branch portion37extend through the tubular body15.FIG. 5Calso shows a seam40in the graft material20which will be described in greater detail below. In the distal lateral300cross-section (FIG. 5D), the main lumen16extends through the endograft10.

In order to better understand the structure and construction of the endograft shown inFIGS. 5A to 5D, one method of constructing the endograft10shown inFIG. 5Awill now be described with reference toFIGS. 1-4. In particular, one novel feature of the disclosed endograft10is that the internal branch portion37is constructed using the excess of the graft material20used to make the tubular body15, thus eliminating or reducing the need to sew a separate branch to the graft material.

FIG. 1is a plan view of a flattened tube of biocompatible material with a 12 o'clock line down its centre.FIG. 2is a similar view to that ofFIG. 1but shows the 12 o'clock line on the right hand lateral edge of the tube.

Referring toFIG. 1, a tube of biocompatible material that may form the tubular body15is shown. In particular, tubular wall17of the endograft10is shown in a flattened condition so as to form two parallel spaced-apart folds that define tubular wall portion18and tubular wall portion19. Referring toFIG. 1, a 12 o'clock line450is marked on the graft material20. Further lines410and420are marked on the graft material20. Lines410and420may represent a portion of the outline of the internal branch portion37. The line420indicates the position that will become the recess or opening250and the exit34from the branch lumen36.

FIG. 2shows the graft material20folded at the 6 and 9 o'clock position aligning the lines410with each other.

As shown inFIG. 2, the flattened graft material may be partitioned by sewing a seam40along the internal branch lines410. In other words, a seam40may attach two portions of the graft material20together along line410. The seam40may be sewn using any suitable method and may be sewn using any suitable biocompatible material.

After the seam40is sewn, an excess portion15′ of graft material20may be cut out and discarded. In one example, a longitudinal cut may occur near the seam40at longitudinal edges214and216. Two adjacent longitudinal edges214and216may join each other along the seam40. A latitudinal cut may occur at lateral edge218.

The graft material20may be sealed my any means along one or more cut lines. In one example (shown inFIG. 3b), the graft material20is heat sealed along longitudinal edges214and216as described below.

The seam40may extend from the distal end portion30of the endograft10to a point proximal to the lateral edge218. A branch portion37may be formed in the tubular wall17area between the seam40and the 12 o'clock line450. The branch portion37may have a mouth38and an exit34that connects the branch portion37to the tubular body15.

FIGS. 3A and 3Bshow end views of the flattened tube ofFIG. 2after a seam40has been sewn and a portion15′ of the graft material20has been cut out and discarded. In particular,FIG. 3Ais an end view of the tube ofFIG. 2after a longitudinally extending portion from the tubular wall has been cut out.FIG. 3Bis a similar view toFIG. 3Abut shows the tube after edges214and218formed from a cut have been heat sealed.

As shown inFIGS. 3A and 3B, the tubular wall portions18and19are sewn together to form the seam40. Adjacent longitudinal edges214and216join each other at a lateral edge218. All of the edges214,216and218are formed when the excess graft material15′ is cut and discarded. This leaves a lateral edge218and the mouth38of the internal branch portion37.

FIG. 4Ais an isometric view showing the tube ofFIG. 3B. As shown inFIG. 4A, the graft material20is no longer in a flattened configuration, but rather in a tubular configuration. The seam40occurs along the graft material20along line410and the excess graft material has been cut away. The mouth38to the internal branch portion37is illustrated inFIG. 4A.

FIGS. 4B, 4C and 4Dare proximal lateral, intermediate lateral and distal lateral cross-sections through the tube shown inFIG. 4Athrough section lines4B-4B,4C-4C and4D-4D respectively. As shown inFIG. 4B, the graft material forms a tubular wall17with main lumen16. At the intermediate lateral cross-section,FIG. 4Cillustrates addition of the branch portion37having a lumen36.FIG. 4Calso shows the seam40in the tubular wall17. At the distal lateral cross section4D-4D shown inFIG. 4D, the tubular wall17and the seam40are illustrated.

It may be desirable to provide additional support to the internal branch portion37. In one example, a super-elastic ring of nitinol wire is attached to support the branch portion37. For example, space frame41may provide additional support to the internal branch portion37.FIG. 8is an isometric view of a space frame.FIG. 9is an isometric view showing the space frame ofFIG. 8attached to the internal branch portion37shown inFIG. 4A.

As shown inFIGS. 8 and 9, it can be seen that the branch portion37may have a space frame41. The space frame41may have an entrance reinforcing ring43and an exit reinforcing ring47. The entrance and exit reinforcing rings43,47may be spaced apart axially by one or more struts44and48. In one example, the space frame41comprises an assembly of two individual ring and strut components42,46. Each ring and strut component42,46may comprise a circular ring portion defining a plane of the circular ring portion and a strut extending at right angles to the plane of the circular ring portion from a periphery of the circular ring portion. One of the two circular rings may form the entrance reinforcing ring43and the other of the two circular rings may form the exit reinforcing ring47. For instance, ring and strut component42may comprise the entrance reinforcing ring43and the strut44. Ring and strut component46may comprise the exit reinforcing ring47and strut48.

As shown inFIG. 9, the space frame41may be attached to the branch portion37in any suitable way. In one example, space frame41is sewn into the branch portion37with stitching49. The mouth38of the branch portion37may be biased towards an open condition by the entrance reinforcing ring43. Similarly, the exit reinforcing ring47may bias the exit34(shownFIG. 6) into an open condition. This open condition is also apparent in the isometric view ofFIG. 7looking down into the endograft10from its proximal end12.

The space frame41may be constructed with any biocompatible material. In one example, the space frame41comprises super-elastic wire, such as Nitinol. Other suitable materials may be used.

The tubular body15graft material20shown inFIGS. 1-4 and 8-9may be everted or turned inside out so that the branch portion37sits internally in the tubular body15, as shown in the endograft10shown inFIGS. 5-7 and 10-11.FIGS. 5A-Dshow one example of an endograft10after it has been constructed according to the disclosure above.

Returning toFIGS. 5A-D, once the tubular body15graft material20is turned inside out, stents13,22,24,26,28, and29may be attached to the tubular wall17by any known method including using adhesives and stitching. Once the branch portion37is located internally in the tubular body, the shape of the branch portion37may further be changed as desired. For example, the branch portion37may be further cut and heat sealed to any desirable shape. In one example, excess tubular wall material may be cut out and the resultant slits may be sewn to form seams272and274. In other words, the excess material may be gathered and trimmed to create a V-shape (as shown inFIG. 5A).

As shown inFIG. 5A, the recess or opening250in the tubular wall17may open into the exit34of the branch portion37. The recess or opening250may be at least partially disposed within a V-shaped region260formed between two adjacent struts22a,22band a bend22cof zig zag stent22, that stent22being one of the plurality of zig zag stents21as is shown most clearly inFIG. 5A. In one example, the tubular wall17of the main lumen may have at least one seam40adjacent to the V-shaped region260formed between two adjacent struts and a bend of one of the plurality of zig zag stents21.

As shown inFIG. 5A, the tubular body15of the endograft10may include a proximal portion100, an intermediate portion200and a distal portion300. The tubular body15of the endograft10may have a seam40extending longitudinally along a portion of the tubular wall17.

FIGS. 5B, 5C and 5Dshow lateral cross-sections of the endograft ofFIG. 5Athrough section lines5B-5B,5C-5C and5D-5D respectively. In the proximal portion (shown inFIG. 5B), the tubular wall17has a main lumen16. In the intermediate portion200(shown inFIG. 5C) the internal branch portion37and the branch lumen38may be within the main lumen16. Referring again toFIGS. 5A, 5B, 5C, 5D and 6, it can be seen that a seam40may be created where the tubular wall17is pinched together to form a branch portion37. In the distal portion (shown inFIG. 5D), the distal end14of the endograft can be seen as well as the seam40formed where the tubular wall17is stitched after the excess graft material has been cut out and discarded.

FIG. 6is a longitudinal cross-sectional view of the endograft ofFIG. 5A.FIG. 7is an isometric view looking into the endograft ofFIGS. 5A and 6from its proximal end.

Referring to the longitudinal cross-sectional view ofFIG. 6, the internal branch portion37can be seen internal to the tubular body15. With this cross-sectional view, the external stents22,24,26and the wires of the space frame41are not shown (the space frame41is shown inFIG. 8and is described below).

The branch portion37comprises an entrance32into the main lumen16within the intermediate portion200of tubular body15. The branch portion37may have an exit34through the tubular wall17of the tubular body15. The exit34through the tubular wall of the main lumen16may open into the recess or opening250. A lumen16may run between the entrance32and the exit34.

Referring now toFIG. 7, which is an isometric view looking down into the endograft10from its proximal end12, the branch portion37can be seen within the main lumen16. The proximal end of the branch portion37may have a larger diameter than the distal end of the branch portion37.

The deployment of one embodiment of the endograft10can occur in any vessel, duct, or lumen. The endograft10may be deployed in a patient using any known technique or method. In one example, the deployment device is the device disclosed in U.S. Pat. No. 7,537,606 titled Branch stent graft deployment and method, which is herewith incorporated in its entirety into this specification.

In one example, endograft10can be deployed into the thoracic arch of a patient.FIG. 10Ais a diagrammatic view of the endograft ofFIGS. 5A, 6 and 7within the anatomy of a patient.FIG. 10Bis a similar view to that ofFIG. 10Abut also shows a side branch endograft.

The thoracic arch region of a patient generally comprises an ascending aorta502extending from an aortic valve550of the heart of the patient, then over the thoracic arch to the descending aorta522. From the thoracic arch, three main arteries extend. These are the innominate artery, the left carotid artery520and a subclavian artery510. This embodiment of the disclosure will generally be discussed with reference to deployment of an endograft10in the form of a stent graft10with a side branch into the aorta500and left subclavian artery510but the disclosure is not so restricted.

The endograft10may be necessary in the aortic arch region when an aneurysm in the aorta500extends up the aorta500to such an extent that there is insufficient patent aortic wall to provide good sealing for a stent graft10distally of the left subclavian artery510(for instance, see aneurysmal portion505inFIG. 10A). It is desirable in such circumstances to extend the stent graft10to seal onto good artery wall at least between the left carotid artery520and the left subclavian artery510.

The proximal end sealing region11is shown inFIGS. 10A and 10Bsealing onto good artery wall at least between the left carotid artery520and the left subclavian artery510. The distal end sealing region29is also shown inFIGS. 10A and 10Bsealing onto good artery wall along the descending aorta522below the aneurysmal portion505.

FIG. 10Ashows a detailed view of the deployed stent graft10, as shown inFIG. 5A, into a thoracic arch of a patient. A separate balloon expandable, or self expanding, side arm or side branch endograft60such as stent graft60can then be deployed brachially through the subclavian artery510so that its upstream or proximal end enters the branch lumen36and then it can be allowed to expand, or be balloon expanded, so that the proximal end is expanded within the branch portion37to seal the side branch stent graft60into the branch lumen36of the main stent graft10, as is shown inFIG. 10B. In other words, the recess or opening250may be adapted to accommodate a side arm, the side arm having an upstream end and a downstream end, the upstream end positionable within the branch lumen and the downstream end within a branch vessel. Again, this can be achieved as is described in the afore-mentioned U.S. Pat. No. 7,537,606 titled Branch stent graft deployment and method.

FIG. 11is an isometric view of an alternative endograft10′ according to the disclosure. With this embodiment, the distal most stent27′ is an external stent. That is, the stent27′ is secured on the outside of the tubular body15. This endograft10′ can be used as part of an interconnected stent graft assembly where a more distal stent graft seals to the inside of the distal end of the endograft10′. Such an arrangement may be suitable for a patient who has an aneurysm that extends further down the descending aorta that the aneurysm505shown inFIGS. 10A and 10B.

The above described method of producing the endograft10utilises excess graft material20to produce the branch portion37. This eliminates the need to separately fabricate and attach the branch portion37, reducing the complexity of the final endograft10or endograft10′, as illustrated inFIGS. 5A and 11respectively.

The disclosure is not limited to this particular application but is discussed in relation to this particular application as an example.

Embodiments of the disclosure will be used by vascular surgeons to treat aneurysms and to repair regions of the aorta, including, but not limited to, the aortic arch. Embodiments of the disclosure will be used in other parts of the vasculature system.

It will be appreciated by those skilled in the art that the disclosure is not restricted in its use to the particular application described. Neither is the present disclosure restricted in its preferred embodiment with regard to the particular elements and/or features described or depicted herein. It will be appreciated that the disclosure is not limited to the embodiment or embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the scope of the disclosure as set forth and defined by the following claims