WO2021101827A1

WO2021101827A1 - Stent graft, assembly and endovascular aortic repair methods

Info

Publication number: WO2021101827A1
Application number: PCT/US2020/060679
Authority: WO
Inventors: Athanassios TSOUKAS; John Matthew MULLINS; Lucy Dolores HALPIN
Original assignee: Tsoukas Athanassios
Priority date: 2019-11-18
Filing date: 2020-11-16
Publication date: 2021-05-27

Abstract

A branched stent graft system includes an elongate main stent graft extending along a central longitudinal axis. The main stent graft is configured for deployment in a main vessel and has a cell zone extending along the axis and has a wire mesh and a puncturable wall divided by the wire mesh into a plurality of cells, which includes at least one cell defining a through hole in the wall of the cell. The system also includes a branch stent graft having a tubular body extending longitudinally from a proximal end to a distal end. The branch stent has a flange extending from the proximal end and the flange has an outer diameter that is larger than a diameter of the through hole. The branch stent extends through the hole and is fluidly sealed at the flange to an inner surface of the cell zone surrounding the through hole.

Description

STENT GRAFT, ASSEMBLY AND ENDOVASCULAR AORTIC REPAIR

METHODS

BACKGROUND

1. Field

[0001] The present disclosure relates to stent grafts, to branched endografts using the stent grafts, and to endovascular aortic repair procedures (EVAR).

2. State of the Art

[0002] Stent grafts are used in transcatheter endovascular aortic repair (EVAR) procedures to seal abdominal aortic aneurysms (AAAs). The grafts typically include either a self-expanding stent (frame) or a balloon-expandable stent that is covered with material to seal the vessel walls and prevent blood leaks feeding the aneurysm. The stent graft frame are often made of medical grade stainless steel, cobalt alloy, or nickel -titanium alloy. The cover material is often made from polytetrafluoroethylene (PTFE).

[0003] Standard EVAR procedure assumes that the aneurysm is infrarenal with an adequate size, normal infrarenal aortic neck for the satisfactory infrarenal fixation of the stent graft device. However, a significant number of patients present “difficult” infrarenal necks with acute angles, thrombus, calcium, or shortness. In these cases suprarenal fixation and preferably suprarenal deployment of the graft is required for ideal apposition and resultant durability. Accordingly, branched endografts are required. These branched endografts are made based on two-dimensional imaging of the patient, preloaded on the graft, and result in a device which is big and difficult to deliver to the aneurysm site. In addition, the procedure for delivering and placing the branched endograft properly is technically demanding and can easily take 8 to 10 hours, even in experienced hands. It will be appreciated that such a long procedure can pose significant risks to compromised patients.

[0004] Besides infrarenal aneurysms, patients may experience other types of aneurysms. For example, some patients may experience suprarenal aneurysms, which extend above the renal or visceral arteries, sometimes well into the chest. Also, some patients may experience juxtarenal aneurysms while presenting “difficult” juxtarenal necks with acute angles, thrombus, calcium, or shortness.

SUMMARY

[0005] In accordance with one aspect of the disclosure, a stent graft configured for deployment in a vessel has at least three fluidly -coupled zones including a top fixation zone with hooks and a first construction, an intermediate zone of wire elements forming a second rounded (e.g., hexagonal) cell construction different than the first construction and with the top fixation zone and intermediate zone being coaxial, and a lower zone with the third construction different than the second construction and bifurcated into two tubular segments at the bottom. The stent graft is covered along at least a portion of the top fixation zone, the intermediate zone, and the lower zone with a wall material such as PTFE. The intermediate zone covering is puncturable. The first construction and third construction may be similar and may be a standard zig-zig construction such as is commonly found in a Palmaz-type stent.

[0006] In embodiments, the walls of a many or all of the cells of the intermediate zone are dimpled, stitched, or perforated. In embodiments, the walls of the cells of the intermediate zone are configured to be cut with at least one of a drilling tool, a laser, and a heating tool. In embodiments, the walls of the cells of the intermediate zone include a plurality of planar panels frangibly joined along respective edges to form a funnel when opened.

[0007] In embodiments, the stent graft has a diameter of between 26 mm and 40 mm (and selectively chosen for the anatomy of the patient). The top fixation zone has a length (height) of between 2 and 5 cm. The intermediate zone has a length of between 3 and 6 cm, with the diameter of each cell being between about 7 to 10 mm. The bottom zone has a length of about 5 cm, with at least one of the legs of the bifurcation optionally extending longer. The bifurcated legs may each have a diameter of between 10 and 16 mm. [0008] According to one aspect, the intermediate zone of the stent graft is adapted to have one or more branch endografts attached in situ (in the patient’s body) and sealed in situ. The branch endografts may be self-expanding or may be expandable via balloon pressure. The branch endografts are typically 5 to 10 cm in length and 6 to 9 mm in diameter and may have flared ends with a distal end intended for insertion into a peripheral artery such as the renal artery and fixation thereto, and a proximal end intended for engagement with the main stent graft. Accordingly, the flange has an outer diameter that is larger than a diameter of the through hole. The branch stent extends through the hole and is fluidly sealed at the flange to an inner surface of the cell zone wall surrounding the through hole. Thus, in embodiments, the main stent graft is deployed into the main vessel of a patient before introducing one or more branch stent grafts into the main stent graft, through one or more holes made in one or more cells of the intermediate zone and out into the peripheral artery, and sealing the branch endograft to the main stent graft in-situ.

[0009] In embodiments, the through hole in the intermediate zone is formed by puncturing the wall from within the central lumen of the main stent graft. In embodiments, forming the through hole includes introducing a hole forming tool through the central lumen, and forming the through hole using the tool. The tool may be one of a drill and a laser. In embodiments, the hole forming tool is guided by a catheter inserted through the central lumen.

[0010] In embodiments, a pressure sensitive adhesive is on or otherwise applied to the outer surface of the flange, i.e., the surface facing the inner surface of the cell zone wall surrounding the through hole. Also, in embodiments, a first hook and loop fastener is on or otherwise applied to the outer surface of the flange and a second hook and loop fastener is on or otherwise applied to the inner surface of the cell zone wall surrounding the hole. The first and second hook and loop fasteners fasten together to thereby fasten the flange and the inner surface of the cell zone together.

[0011] In embodiments, the system includes a film wrapped around an outer surface of the cell zone wall. The film has a plurality of film holes corresponding to the plurality of cells, and each film hole is centered with each corresponding cell. Each film hole is undersized with respect to the size of the through hole formed in a respective cell. In embodiments, the branch stent extends through a respective film hole aligned with the through hole. The film is a stretch film configured to deform and conform to an outer surface of the body of the branch stent extending through the film hole.

[0012] According to one aspect a method of assembling a branched stent graft system is provided. The method includes providing the previously described elongate main stent graft and one or more of the previously described branch stent endografts. Guide wires are inserted into a first iliac artery via an incision in the groin area, with a first guide wire extending through the aortic aneurysm and guided into first renal artery, and a second guide wire extending through the aortic aneurysm and guided into a second renal artery. Optional additional guide wires may be used to extend through the aortic aneurysm and guide into the mesenteric, celiac, or other suprarenal arteries. Another guide wire is inserted into a second iliac artery via an incision in the groin area (of the other leg) and guided through the aneurysm. A catheter housing the main stent of desired length is then pushed over the guide wire extending through the second iliac artery until the stent is located in a desired location, and the catheter is then retracted to permit the main stent to expand with its top fixation zone engaging the aorta above the aneurysm, and one of the legs of the bifurcated bottom zone located in and engaging the second iliac artery.

[0013] With the main stent in place, and the plurality of guide wires extending from the first iliac artery, outside the main stent (in the aneurysm) and into the peripheral arteries, a steerable sheath or catheter is introduced through the second iliac artery and into the body of the main stent graft. The steerable sheath or catheter is steered (under fluoroscopy) and inside the stent graft up to the location of the first renal artery. A hole forming tool is deployed or introduced into the sheath or catheter into engagement with the wall of the main stent graft at a cell location nearest (in alignment with) the first renal artery. The tool is then operated to form a through hole in the wall of the cell. A guide wire (eventually used for a branch endograft) is then introduced through the sheath, out of the hole and into the first renal artery. In embodiments, introduction of the branch endograft guide wire into the first renal artery may be aided by an electromagnet/snare system deployed along the external guide wire which extends into the first renal artery and which may be used to grab (capture) the branch endograft guide wire extending through the through hole and pull it into the first renal artery. Then, the first branch endograft as previously described is introduced by catheter over the branch endograft guide wire through the second iliac artery into the main stent, out through the through hole and into the first renal artery. With the branch endograft located with its proximal flange (or flared) end just inside the main stent wall and its distal end located inside the first renal artery, the catheter containing the branch endograft is retracted, and the branch endograft either self- expands or is caused to expand (typically via balloon) to seal the branch endograft to the main stent graft. The seal between the branch endograft and the main stent may be aided by applying a radially outward pressure to the flange from within the central lumen of the main stent graft.

[0014] According to embodiments, additional branch endografts may be connected to the main stent graft by repeating the procedure and using the other guidewires extending from the first iliac artery into the second renal artery and other suprarenal arteries.

[0015] In accordance with another aspect of the disclosure, a medical kit includes at least one main stent graft, a plurality of branch endografts, a plurality of guide wires, a plurality of catheters including at least one steerable catheter, and a hole forming tool.

[0016] The main stent grafts, systems, kits, and methods described herein may be useful in the treatment of suprarenal aneurysms, as well as infrarenal and juxtarenal aneurysms with “difficult” infrarenal and juxtarenal necks.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Fig. 1 shows a branched aortic stent graft, which includes a main stent graft and at least one branch stent graft (two are shown), in a fully assembled and implanted condition.

[0018] Fig. 2 shows a detailed view of the branched aortic stent graft of Fig. 1. [0019] Fig. 3 A shows the placement of one guide wire through the aorta and a corresponding branch artery.

[0020] Fig. 3B shows the placement of two guide wires through the aorta and corresponding branch arteries.

[0021] Fig. 3C shows the placement of three guide wire through the aorta and corresponding branch arteries.

[0022] Fig. 3D shows the placement of three guide wire through the aorta and corresponding branch arteries. Note one of the guidewires can be inserted supraclavicular to avoid congestion in the aortic vessels.

[0023] Fig. 4 shows the placement of the main stent graft of Fig. 1 after the placement of the two guidewires shown in Fig. 3B.

[0024] Fig. 5 shows a steerable catheter deployed to a target location juxtaposed to a target branched vessel to placement of branch stent graft.

[0025] Figs. 6A and 6B show an embodiment of puncturing a hex cell of the main stent graft using a drilling tool deployed through the catheter.

[0026] Figs. 7A and 7B show an embodiment of puncturing a hex cell of the main stent graft using a heating/cutting element deployed through the catheter.

[0027] Figs. 8A to 8C show an alternate embodiment of the cell zone of the main stent graft with hexagon cells having petals configured in a conical arrangement, which form a funnel that aid in locating the catheter in the center of conical petal configuration.

[0028] Fig. 8D shows one of the cells of Figs. 8 A to 8C opened and with a branch stent graft fluidly coupled to the petals.

[0029] Figs. 9A and 9B show an embodiment of puncturing a hex cell of the main stent graft using a laser deployed through the catheter. [0030] Figs. 10A and 10B show an alternate embodiment of a cell of the cell zone of the main stent graft with hexagon cells embossed with a dimple shape at the center of the cell.

[0031] Fig. IOC shows one of the cells of Figs. 10A and 10B punctured (for example, by a laser or drill) to form a hole and with a branch stent graft fluidly coupled to the main stent graft through the hole.

[0032] Fig. 11 shows a ferromagnetic tip extending from the steerable catheter and a snare and electromagnetic tip extending from a catheter guided by one of the guidewires extending in the target branch vessel.

[0033] Figs. 12A and 12B show deployment of a side branch stent graft through the hex cell in which the hole was formed coinciding with the targeted branched vessel.

[0034] Fig. 13 A shows one embodiment of a sealing film applied to the cell zone of the main stent graft.

[0035] Fig. 13B shows an assembly view of a portion of the main stent graft shown in Fig. 13 A.

[0036] Fig. 13C shows a side branch stent graft extending through an opening in one of the cells shown in Fig. 13 A and sealed to the seal film.

[0037] Fig. 14 shows an embodiment of a sealing arrangement between a branch stent graft and a main stent graft of a branched aortic stent graft in accordance with an aspect of the disclosure.

[0038] Figs. 15A and 15B show an example of a balloon catheter used to seal the flange of the branch stent graft to the main stent graft in Fig. 14. In Fig. 15A the balloons of the catheter are deflated and in Fig. 15B the balloons are shown inflated.

[0039] Fig. 16 shows the deflated balloon catheter of Fig. 15A introduced into the branch stent graft from within the interior of the main stent graft and through a hole in a cell of the cell zone of the main stent graft. [0040] Fig. 17 shows the arrangement of Fig. 16 with the balloons of the catheter in an inflated configuration pressing the flange of the branch stent graft and the wall of the cell zone together.

[0041] Fig. 18 shows the branch stent graft fully sealed and connected to the main stent graft with the balloon catheter removed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] Fig. 1 shows a branched aortic stent graft 100 in a fully assembled and expanded configuration implanted in a main vessel 202 (aorta) and branch vessels 204 (e.g., renal arteries). The branched aortic stent graft 100 includes a main stent graft 102 configured to be disposed in and extend along the length of an aneurysm 202a of the main vessel 202 and one or more branch stent grafts (two are shown in Fig. 1) 104 fluidly connected to the main stent graft 102 and configured to be disposed in respective branch vessels 204. The branch stent grafts 104 are sealed to the main stent graft 102 so that there is a fluid tight seal therebetween. In embodiments, the branched aortic stent graft 100 is configured to be assembled from a kit from its constituent parts including the main stent graft 102 and branch stent grafts 104. As will be described in greater detail herein, the assembly of the branched aortic stent graft 100 can be performed in situ in the patient e.g., with a surgeon making the connections within the main and branch vessels 202 and 204.

[0043] The main stent graft 102 and the branch stent grafts 104 are generally tubular with metal stent portions and a fabric (e.g., PTFE) sheath 105 and define respective lumens extending longitudinally along respective central axes A-A and B- B. The main stent graft 102 is configured to assume a radially expanded configuration when deployed in the main vessel 202, as shown in Fig. 1. Also, each branch stent graft 104 is configured to assume a radially expanded configuration when deployed in a respective branch vessel 204, as shown in Fig. 1. The main and branch stent grafts 102 and 104 may assume a radially compressed configuration during positioning in the respective main and branch vessels 202 and 204 and before deployment therein, upon which the stent grafts are permitted to radially expand. The main stent graft 102 as well as the branch stent grafts 104 can be produced having various expanded sizes (e.g., axial length and diameter) to accommodate various sizes of vessels. For example, the main stent graft 102 can be produced in several diameters from 26 to 40 mm in their expanded configuration.

[0044] The main stent graft 102 has a plurality of zones 106, 108, and 110 located along the length of the main stent graft 102. For example, in the embodiment of the branched aortic stent graft 100 shown in Figs. 1 and 2, the main stent graft 102 includes an upper fixation zone 106, a middle or intermediate cell zone 108, and a lower endograft zone 110. The upper zone 106, cell zone 108, and lower zone 110 are coaxial with axis A-A and are fluidly connected to one another in a fluid tight manner so that there is a fluid tight pathway axially through the entirety of main stent graft 102.

[0045] The upper and lower zones 106 and 110 may have a conventional aortic stent construction (e.g., a Palmaz-type stent construction) including an expandable wire (e.g., a zig-zag construction made from stainless steel (316L), cobalt-chromium alloys, nickel -titanium alloy (Nitinol), platinum, or tantalum alloys) covered by a flexible sheath 105 (made from spun PTFE). The upper fixation zone 106 includes hooks 106a at an upper portion for subintimal fixation of the main graft. For various main stent grafts 102, the length (measured along central axis A-A) of the fixation zone 106 may extend between 2 and 5 cm to accommodate variation in the anatomy of various patients. Also, the fixation zone 106 can contain scallops 106b for the celiac axis.

[0046] The lower, endograft zone 110 has a main tubular segment 110a and two tubular segments (e.g., femoral sheaths) 110b and 110c. The main tubular segment 110a is fluidly sealed with the cell zone 108. The lower zone 110 may have a length (along axis A-A) of about 5 cm. In one embodiment, each segment 110b, 110c is between 10 and 16 mm in diameter, and they may have the same diameter, such as 14 mm. The segments 110b and 110c may have different lengths, as shown in Figs. 1 and 2.

[0047] The cell zone 108 includes a tubular wire mesh 108a and a tubular puncturable cell zone wall 108b (e.g., made from PTFE) extending along and covering the wire mesh 108a. The wire mesh 108a defines a plurality of cells 108c. The cell zone wall 108b includes a plurality of cell walls 108w enclosing each of the cells 108c. The wire mesh 108a is compliant so that the cells zone 108 can radially contract and expand with the other zones 106 and 110 during deployment of the main stent graft 102. Also, the wire of the wire mesh 108a surrounding each cell is configured to limit the radial expansion of branch stent grafts 104 that extend through holes 108d formed in cell walls 108w of cells 108c, further details of which are described hereinbelow.

[0048] The wire mesh 108a defines the perimeter of each cell 108c. The perimeters of the cells 108c may have various geometric shapes, such as hexagons, which for purposes herein are considered “rounded”, as shown in the embodiment of Figs. 1 and 2. In one embodiment, the “diameter” (i.e., the maximum dimension between two vertices) of each cell is between about 7 and 10 mm. The cell zone 108 may have a length (measured along axis A-A) of about 3 cm to about 6 cm to cover an axial length of the visceral aortic segment for various patients. As shown in Fig. 1, when deployed in the patient’s aorta (i.e., main vessel 202), the cell zone 108 is disposed at or near the visceral aortic segment of the aorta 202 so that at least one cell 108c of the cell zone 108 coincides or otherwise aligns with a branch vessel 204 that is to receive the branch stent graft 104, as shown in Fig. 1.

[0049] The main stent graft 102 is configured to fluidly connect to at least one of an assortment of self-expanding branch stent grafts 104 through corresponding through holes 108d (Fig. 1) formed in-situ in the cells of the cell zone 108, as will be described in greater detail hereinafter. As shown in greater detail in Fig. 12B, each branch stent graft 104 has an elongated body 104a that extends along a respective axis B-B from a proximal end 104’ to a distal end 104”. The proximal end 104’ may have a larger diameter than the distal end 104” and the wall of the branch stent graft (e.g., outer surface) 104 may be tapered from the proximal end 104’ to the distal end 104”. Both of the proximal and distal ends may have outwardly extending flares or flanges. The distal end 104” is configured to be introduced through a corresponding opening or hole 108d that can be formed in the cell 108c in-situ, as will be described in greater detail hereinafter. The hole 108d is made to coincide with or otherwise align with the branch vessel 204 that is to receive the branch stent graft 104.

[0050] The proximal end 104’ of the body 104 is configured to fit within a diameter of a hole 108d in at least one cell of the plurality of cells 108c, which diameter can be equal to the diameter of the cell 108c. The proximal end 104’ of the body 104a of the branch stent 104 may have a diameter of about 11 mm to 12 mm. In embodiments, the diameter of the proximal end 104’ is about 20% oversized (11 mm to 12 mm) to fit a cell having a diameter of about 1 cm. The distal end 104” may have a diameter of about 6 mm to about 9 mm for deployment into the branch vessel 204. The outer surface of the body 104a between the proximal and distal ends 104’ and 104” may be tapered. The branch stent grafts 104 may have a length (along axis B-B) of about 5 cm to about 10 cm.

[0051] In one embodiment, the branch stent 104 has an annular flange 104b that extends radially from a proximal end 104’ of the body 104a of the branch stent 104. The flange 104b may be continuous with the wall of the body 104a and may be formed by flaring the proximal end 104’ of the body 104a. The flange 104b has an outer surface that is configured to seal with an interior surface of the cell zone wall 108b surrounding the hole 108d formed in the cell wall 108w of the cell 108c. The interior surface of the cell zone wall 108 to which the flange 104b seals may encompass other cells 108c that are near or adjoining the respective cell 108c in which the hole 108d is formed. In one embodiment, the flange 104b may extend radially outward from the proximal end 104’ of the body 104a about 1 mm to about 2 mm. The flange 104b has an outer diameter that is larger than the diameter of the cells 108c, e.g., 1 cm.

[0052] The following will describe an embodiment of a method of implantation and in-situ assembly of the branched stent graft 100 in accordance with an aspect of the disclosure. As an initial step, after making an incision in the groin area, one or more visceral guide wires 300 (Figs. 3A-3D) are directed through an iliac artery 205a and into the main vessel 202 and to the branch vessels 204. In the following description of the method, two guide wires 300 are used as shown in Fig. 3B, leading into the renal arteries 204. However, as shown in Figs. 3C and 3D, three or more guide wires 300 can also be used and may extend into the renal arteries and mesenteric, celiac, or other suprarenal arteries. Also, it is noted that as shown in Fig. 3D, one or more guide wires 300 can be inserted supraclavicular to avoid congestion in the main vessel 202.

[0053] Once the guide wires 300 are deployed into the branch vessels 204, the main stent graft 102 can be deployed into the main vessel 202 through the segment 110c of lower zone 110 that does not contain guide wires 300, as shown in Fig. 4. More particularly, another guide wire (not shown) is inserted into a second iliac artery via an incision in the groin area (of the other leg) and guided through the aneurysm 202a. A catheter (not shown) housing the main stent graft of desired length is then pushed over the guide wire extending through the second iliac artery until the stent graft is located in a desired location, and the catheter is then retracted to permit the main stent graft to expand with its top fixation zone engaging the aorta 202 above the aneurysm 202a, and one of the legs 110c of the bifurcated bottom zone located in and engaging the second iliac artery 205b.

[0054] It will be appreciated that the main stent graft 102 is deployed into the main vessel 202 so that the guide wires 300 remain external to the lumen of the main stent graft 102. Also, the main stent graft 102 is deployed so that the length of the cell zone 108 extends along the branch vessels 204 in which branch stent grafts 104 are to be deployed, and with the upper zone 106 deployed in the diaphragmatic aorta to fix the upper zone 106 to the main vessel 202, and leg 110c of the lower zone 110 deployed in the iliac artery 205b to fix the lower zone therein.

[0055] As shown in Fig. 5, a steerable sheath 500 and catheter 502 within the sheath are introduced into a lumen of segment 110c and the lumen of the main stent graft 102. The sheath 500 may measure about 5 mm in diameter and may be made from hydrophilic (glide) material. The sheath 500 can be made in various lengths, such as 45, 60, and 90 mm. The sheath is configured to flex over 90 degrees along the distal 4 cm of its length. Also, the sheath is steerable in at least one plane. A distal end 500a (Fig. 6b) of the steerable sheath 500 is advanced and curved at 90 degrees and the sheath 500 is positioned to mimic the guidewire 300 (the right guide wire 300 in Fig. 5) that is located in the branch vessel 204. The sheath 500 is advanced (e.g., under fluoroscopy) until a distal end 500a of the sheath 500 is located at one of the cells 108b that coincides or otherwise aligns with the branch vessel 204 that is to receive a branch stent graft 104. As will be described in greater detail below, the catheter 502 is used to deliver a hole forming tool to form a hole 108d in the cell wall 108w of a cell 108c through which a branch stent graft 104 can be deployed.

[0056] In one embodiment shown in Figs. 6A and 6B, a drilling tool 600 with a high speed rotating drill bit 602 extends from a distal end of the catheter 502 and is then activated (i.e., rotated) to drill a hole through the cell wall 108w of a respective cell 108c. In one embodiment, the drill bit 602 is permitted to extend beyond the distal end 500a of the sheath about 2 mm to 3 mm. The hole 108d may have a diameter of about 4 mm to 5 mm. In embodiments, once the hole 108d is formed, the steerable sheath 500 can be advanced to protrude through the hole 108d after which the catheter 502 can be withdrawn from the sheath 500. In another embodiment shown in Figs. 7A and 7B a heating/cutting tool or element 700 is introduced through the catheter 502 to cut a hole in a cell wall 108w’ of a cell 108c’, which is shown having an alternate construction to cell 108c. As show in in greater detail in Fig. 7B, each cell wall 108w’ may be constructed with crossing stitching 108e’ that crosses at the center of the cell 108c’. The stitching 108e’ can be configured to melt or cut via the heating/cutting tool or element 700 to enable a controlled penetration of the cell wall 108w’. In the example shown in Figs. 7A and 7B the stitches 108e’ extend longitudinally parallel and perpendicular to the central axis of the main stent graft 102, although other arrangements may be utilized.

[0057] Figs. 8A to 8C show an alternate cell zone 108” that includes a plurality of hexagonal cells 108c” each having a cell wall 108w” that is formed from six triangular petals or panels (P) joined together into a funnel or pyramid shape (best seen in Figs. 8B and 8C) that protrudes radially outward with respect to the central longitudinal axis A-A of the main stent graft 102. Each panel (P) has a base along a respective edge of the hexagonal cell 108c”. Each triangular panel (P) has two opposed tapered sides (S) joined to adjacent panels (P). The apexes (A) of each triangular panel (P) join at the center of the hexagonal cell 108c”. The protruding and tapered cell wall 108w” structure can facilitate guiding the catheter 502 to find the center of the cell 108c” before cutting or otherwise forming a hole 108d” (Fig. 8D) in the cell wall 108w”. The connections between the tapered sides (S) of the panels (P) are configured to be weaker than the material of the panels themselves so that radially outward force directed at the center of the cell 108c” will cause tearing along the connections of the sides (S) thereby causing the cell wall 108w” to open, as shown in Fig. 8D. Each panel (P) may then act as a flange or sealing surface to connect to mating flange (e.g., flange 104b) of a respective branch stent graft 104, as will be described in greater detail hereinafter.

[0058] Figs. 9A and 9B show yet another embodiment of puncturing a wall 108w of a hex cell 108c of the main stent graft 102 using a laser 900 deployed through the catheter 502.

[0059] Figs. 10A and 10B show an alternate embodiment of a cell zone 108’” with generally hexagonal cells 108c’” each of which has a cell wall 108w’” embossed with a dimple (D) at the center of the cell 108c’” to aid the hole forming tool (e.g., drill 600 or laser 900) to locate the center of the cell 108c’”. Fig. IOC shows one of the cells 108b’” of Figs. 10A and 10B punctured to form a hole 108d’” and with a branch stent graft 104 fluidly coupled to the main stent graft 102 through the hole 108d”\

[0060] Once the hole 108d is formed through the cell wall 108w of the cell 108c, according to one embodiment, the catheter 502 can be further guided through the hole 108d into the branch vessel 204 to cannulate the branch vessel as follows. A (guide) wire can be extended through the sheath 500 that is already protruding through the hole 108d. Such a wire can be guided by the guide wire 300 in the branch vessel 204. Once the branch vessel is cannulated, the branch stent graft 104 can be deployed through the hole 108d guided by the guide wire in the sheath 500 as discussed hereafter. [0061] The following alternative method may be employed to cannulate the branch vessel 204. As shown in Fig. 11, a wire 504 having a ferromagnetic tip 504a can be passed in the direction of the arrow through a distal end 502a of the catheter 502 (that is inside the lumen of the main stent graft 102) and through the hole 108d.

A second optional catheter 1100 (external to the lumen of the main stent graft 102), guided by guide wire 300, can be positioned outside of the main stent graft 102. The second catheter 1100 may be a dual lumen glide catheter. One lumen 1100a serves for wire passage of a wire 1104 with an insulated electrical wire coil 1104a at a tip 1104b of the wire 1104. Another lumen 1100b services for passage of a snare 1102 that is configured to be extended from the catheter 1100 before the wire 1104. The electromagnetic coil 1104a at the tip 1104b can then be deployed from a distal end 1100c of the catheter 1100. The electromagnetic tip 1104 can be energized to generate a magnetic field that is configured to attract or otherwise lure the ferromagnetic tip 504a through the snare 1102. The snare 1102 is closed when the ferromagnetic tip 504a is within the snare 1102, thereby capturing the ferromagnetic tip 504a. The snare 1102 can then be used to navigate the ferromagnetic tip 504a and the catheter 502 along a pathway defined by guidewire 300 through the hole 108d and into the branch vessel 204. It will be appreciated that the use of the coil 1104a and the ferromagnetic tip 504a is optional and may be used to assist the cannulation of visceral vessels that can sometimes prove difficult and otherwise time consuming.

[0062] With the catheter 502 advanced into the branch vessel 204, the branch stent graft (also called “endograft”) 104 may be guided (in a delivery catheter - not shown) through the main lumen of the main stent graft 102 and deployed through the hole 108d into the branch vessel 204, as shown in Figs. 12A and 12B. Upon withdrawal of the delivery catheter, the endograft is released in place and may expand either automatically or via the use of a balloon as described hereinafter. The external surface of the flange 104b is configured to form a mechanical and/or chemical bond with the internal surface of the cell zone wall 108b surrounding the hole 108d to seal the branch stent graft 104 to the main stent graft 102.

[0063] Various sealing connections are possible between the branch stent grafts 104 and the main stent graft 102. For example, Figs. 13A and 13B show one embodiment of a sealing film 1300 applied to the cell zone 108 of the main stent graft 102. The film 1300 is a thin, stretchy material that defines holes 1302. The film 1300 is applied to the cell zone wall 108b so that the holes 1302 are centered with corresponding cells 108c of the cell zone 108. The holes 1302 have a diameter that is smaller than the expanded diameter of the body 104a of the branch stent graft 104 to be inserted into a respective hole 1302. In use, a cell wall 108w of a cell 108c shown in Fig. 13 A can be punctured as described above to form a central hole 108d for deployment of a branch stent graft 104. A branch stent graft 104 (in a radially compressed configuration) can be passed (distal end first) through the aligned holes 108d and 1302. Then, the branch stent graft 104 can be radially expanded (e.g., using a balloon from within the lumen of the body 104a of the branch stent graft 104). As the body 104a of the branch stent graft 104 expands, it deforms (i.e., radially expands) the undersized film hole 1302 causing the film hole 1302 to conform and seal to the contours of the outer surface of the body 104a of the branch stent graft 104, as shown in Fig. 13C.

[0064] Another embodiment of a sealing arrangement between the branch stent grafts 104 and the main stent graft 102 is described below with reference to Figs. 14 to 18. As shown in Fig. 14, pressure activated adhesive or glue 104c can be applied to the outer surface of the flange 104b of branch stent 104 for bonding to an interior surface of the cell zone wall 108b surrounding a through hole 108d. The adhesive 104c may include microspheres of pressure activated adhesive. In embodiments, the adhesive 104c may be applied to the flange 104b as well as around the tubular body 104a near the proximal end 104’ thereof. In embodiments, in addition to the adhesive or glue 104c, the interior surface of the cell zone wall 108b surrounding the hole 108d, as well as the outer surface of the flange 104b (which faces the interior surface of the cell zone wall 108), can include mating interlocking fabric structures 104d,

108e (e.g., VELCRO™ hook and loop fasteners), which are configured to lock or otherwise connect together when pressed together to thereby form a mechanical connection between the branch stent 104 and the main stent 102. In the embodiment shown in Fig. 16, a radially inner annular portion of the flange 104b may have adhesive 104c applied thereto, while a radially outer annular portion around the flange 104b may have interlocking fabric structure 104d attached thereto. [0065] In this embodiment, an interlocking fabric structure 104d can be bonded to or otherwise secured to the interior surface of the cell zone wall 108b (and possibly other portions) of the main stent graft 102 that will be punctured to define the hole(s) 1302. For example, adhesive can be used to bond the interlocking fabric to the cell zone wall 108b (and possibly other portion) of the main stent graft 102. Similarly, an interlocking fabric structure 108e can be bonded to or otherwise secured to the flange 104b of the branch stent graft 104. For example, adhesive can be used to bond the interlocking fabric structure 108e to the flange 104b of the branch stent graft 104. As the branch stent graft 104 is passed through the hole 1302, the interlocking fabric structure 108e secured to flange 104b is aligned with and interlocked to the opposed interlocking fabric structure 104d secured to the cell zone wall 108b of the main stent graft 102 to form a mechanical bond between the proximal end of the branch stent graft 104 and the main stent graft 102. The interlocking of the opposed fabric structures can be aided by the expansion of a balloon that is configured to apply pressure that presses together the opposed fabric structures and interlocks the opposed fabric structures to form the mechanical bond between the proximal end of the branch stent graft 104 and the main stent graft 102.

[0066] In embodiments, microcapsules of adhesive can be infused or otherwise integrated into one or both of the interlocking fabric structures 104d, 108e. The application of pressure that presses together the opposed fabric structures can also act to activate the adhesive microcapsules whereby such microcapsules rupture and release adhesive that forms a chemical bond and seal between the interlocking fabric structures 104d, 108e. One embodiment of a method of applying pressure can be carried out using a balloon catheter 300 shown in Figs. 15A and 15B.

[0067] The balloon catheter 300 has two balloons: a distal non-compliant balloon 302 and a proximal compliant balloon 304. The two balloons 302, 304 are in fluid communication with one another through a central inflation lumen 330 (extending along a central axis C-C), but are otherwise separated axially by a dividing band 308, which is configured to align with the hole 108d in the cell 108c, as described in greater detail below. The balloon catheter 300 is configured to be guided by a guide wire extending through the lumen of the main catheter. When inflated, the non- compliant balloon 302 expands radially and the compliant balloon expands radially and axially with respect to axis C-C.

[0068] As shown in Fig. 16, in one embodiment of a sealing method, the branch stent graft 104 is first located in the hole 108d with the flange 104b of the proximal end facing the interior surface of the cell zone wall 108b surrounding the hole 108d in the cell 108c. Then, the balloon catheter 300 is guided along a guide wire 310 that extends through the lumen 306 of the branch stent graft 104 and the main stent graft 102 until the band 308 is aligned in the hole 108d such that the non-compliant balloon 302 is positioned in the lumen of the branch stent graft 104 and the compliant balloon 304 is positioned in the lumen of the main stent graft 102. Then, as shown in Fig. 17, the balloons 302 and 304 are inflated, which causes pressure to be applied between the flange 104b and the interior surface of the cell zone wall 108b. The pressure activates the glue 104c and fastens the interlocking fabric structures 104d and 108e together, thereby sealing the flange 104b to the main stent graft 102 at the interior surface of the cell zone wall 108b surrounding the hole 108d. The wires of the wire mesh 108a surrounding the cell 108c having the hole 108d function to limit the radial expansion of the branch stent graft 104. Once the seal is made, the balloons 302 and 304 are deflated and the balloon catheter 300 is withdrawn from the branch stent graft 104 and the main stent graft 102, as shown in Fig. 18. Additional branch stent grafts 104 can then be connected to the main stent graft 102 using the foregoing procedures.

[0069] In other embodiments, adhesive or glue can be integrated into one or both of the interlocking fabric structures 104d, 108e or other parts of the branch stent graft 104 and the main stent graft 102 and activated to form a chemical bond and seal between the branch stent graft 104 and the main stent graft 102 by localized application of heat, light, or other electromagnetic energy.

[0070] Regardless of the means and methods for connecting the branch endograft to the main stent graft, the described procedure may be conducted one or more times to assemble in situ a stent graft system with a branch endograft extending into one or more of a first renal artery, a second renal artery, the mesentery, the celiac artery, and other suprarenal arteries. [0071] In embodiments, the main stent graft, stent graft assemblies and methods may be used for aneurysm repair in animals.

[0072] In embodiments, the cells 108c of the cell zone 108 may be approached and punctured from outside the lumen of the main stent graft 102, i.e., from an annular space between the main vessel 204 and an outer surface of the main stent graft 102. This approach may facilitate repair of aneurysms that extend in the upper chest (to the left subclavian or left common carotid artery). To facilitate locating any of the aforementioned hole forming apparatuses from outside the lumen of the main stent graft 102, the main stent graft 102 may have a modified cell zone with hexagonal cells that are constructed with protruding walls like those described with respect to Figs. 8A-8D and Figs. 10A-10C, but with the cell walls protruding radially inwardly with respect to the central longitudinal axis of the main stent graft 102.

[0073] There have been described and illustrated herein several embodiments of a stent graft, a stent graft assembly, a method of assembling in situ a branched stent graft assembly, and a (EVAR) method of aortic repair using the stent graft assembly. While particular embodiments of the invention have been described, it is not intended that the invention be limited thereto, as it is intended that the invention be as broad in scope as the art will allow and that the specification be read likewise. Thus, while particular materials for the construction of the stent graft have been disclosed, it will be appreciated that other suitable materials may be used. In addition, while particular types of tools for forming holes in cells of a stent graft have been disclosed, it will be understood that any tools for forming a hole in-situ can be used. Also, while particular sealing arrangements between a main stent graft and branch stent grafts has been disclosed, it will be understood that other sealing arrangements may be used.

For example, a heat activated glue or adhesive may be used as an alternative to a pressure activated glue or adhesive. It will therefore be appreciated by those skilled in the art that yet other modifications could be made to the provided invention without deviating from its spirit and scope as claimed.

Claims

WHAT IS CLAIMED IS:

1. A stent graft comprising: an elongate tubular body extending along a central longitudinal axis and defining a central lumen, said stent graft configured for deployment in a main vessel, said stent graft including a plurality of coaxially aligned and fluidly connected tubular zones including: an upper tubular fixation zone having an upper zig-zag wire mesh covered by an upper sheath, said upper fixation zone configured for fixation of said stent graft to the main vessel; a lower zone spaced axially from said upper fixation zone, said lower zone having a zig-zag wire mesh covered by a lower sheath; and a cell zone fluidly connected between said upper fixation zone and said lower zone, said cell zone having a wire mesh defining a plurality of hexagonal cells and a puncturable cell zone wall extending along and covering said wire mesh, said cell zone wall including a plurality of cell walls covering and enclosing each of the plurality of cells.

2. The stent graft according to claim 1, wherein: the stent graft has an expanded diameter of 26 mm to 40 mm.

3. The stent graft according to claim 1, wherein: the cell zone has a length of 3 cm to about 6 cm.

4. The stent graft according to claim 1, wherein: each cell has a diameter of between 7mm and 10 mm.

5. The stent graft according to claim 1, wherein: said lower zone is bifurcated and has tubular segments each of which is configured to be received in a respective vessel in fluid communication with the main vessel.

6. The stent graft according to claim 1, wherein: said cell zone wall is made of polytetrafluoroethylene.

7. The stent graft according to claim 1, wherein: said cell zone wall is dimpled, stitched, or perforated.

8. The stent graft according to claim 1, wherein: said cell zone wall is configured to be opened with at least one of a drilling tool, a laser, and a heating tool.

9. The stent graft according to claim 1, wherein: said cell zone wall includes a plurality of planar panels joined along respective breakable edges.

10. The stent graft according to claim 1, further comprising: a film wrapped around an outer surface of said cell zone wall, said film having a plurality of film holes corresponding to said plurality of cells, each film hole centered with each corresponding cell, and wherein each film hole is configured to deform and seal with a branch stent graft extending through said film hole.

11. The stent graft according to claim 1, further comprising: a hook and loop fastener extending along an interior surface of the cell zone wall.

12. A stent graft system comprising: a stent graft according to claim 1, wherein at least a through hole is formed in at least one cell wall of the plurality cells; and a branch stent graft having an elongate tubular body extending from a proximal end to a distal end, said branch stent graft having a flange extending from said proximal end, wherein said flange has an outer diameter that is larger than a diameter of said through hole, and wherein said branch stent graft extends through said through hole and is fluidly sealed at said flange to an inner surface of said cell zone wall surrounding said through hole.

13. The system according to claim 12, wherein: said branch stent graft has an expanded length of 5 cm to 10 cm.

14. The system according to claim 12, wherein: said body of said branch stent graft is flared at its distal end.

15. The system according to claim 14, wherein: an outer diameter of said body of said branch stent graft at said proximal end thereof is 11 mm to 12 mm, and an outer diameter of said body of said branch stent graft at said distal end thereof is 6 mm to 9 mm.

16. The system according to claim 15, wherein: said flange has an outer diameter larger than a diameter of said through hole.

17. The system according to claim 16, wherein: said hole has a diameter of 4 mm to 8 mm.

18. The system according to claim 12, further comprising: a pressure sensitive adhesive configured to bond and seal said flange to said inner surface of said cell zone wall surrounding said through hole.

19. The system according to claim 12, further comprising: a first hook and loop fastener applied to said outer surface of said flange and a second hook and loop fastener applied to said inner surface of said cell zone wall surrounding said through hole, wherein said first and second hook and loop fasteners are configured to fasten together and thereby fasten said flange and said inner surface of said cell zone wall together.

20. The system according to claim 12, further comprising: a film wrapped around an outer surface of said cell zone wall, said film having a plurality of film holes corresponding to said plurality of cells, each film hole centered with each corresponding cell, and wherein each film hole is undersized with respect to an expanded diameter of said branch stent graft and a size of said through hole through said cell wall of said at least one cell.

21. The system according to claim 20, wherein: said film hole conforms and seals to an outer surface of said body of said branch stent graft.

22. A stent graft kit comprising: a stent graft according to claim 1; and at least one branch stent graft having an elongate tubular body extending from a proximal end to a distal end, said branch stent graft having a flange extending from said proximal end, wherein said flange has an outer diameter that is larger than a diameter of at least one cell of said plurality of cells, and wherein said branch stent is configured to extend through a through hole formed in said at least one cell, and wherein said flange is configured to fluidly seal to an inner surface of said cell zone wall surrounding said through hole.

23. The kit according to claim 22, further comprising: a steerable sheath configured to extend in the lumen of the stent graft; a tool deployment catheter extendable within the steerable sheath; and a hole forming tool extendable from within a lumen of the tool deployment catheter, said hole forming tool configured to form said through hole.

24. The kit according to claim 23, wherein: said steerable sheath has a length of 45 mm to 90 mm.

25. The kit according to claim 24, wherein: said steerable sheath is configured to flex over 90 degrees along 4 cm of its length.

26. The kit according to claim 23, wherein: said hole forming tool includes at least one of a drill and a laser.

27. The kit according to claim 22, further comprising: at least one guide wire configured to extend through a main vessel and into a branch vessel of a patient while remaining outside the lumen of the main stent graft.

28. The kit according to claim 27, further comprising: a ferromagnetic tool deployable through a lumen of the tool deployment catheter, said ferromagnetic tool having a magnetic tip at an end of said ferromagnetic tool; a guide wire catheter configured to slide along said at least one guide wire; an electromagnetic tool deployable through a lumen of said guide wire catheter, said electromagnetic tool having an electric coil at an end of said electromagnetic tool, said electric coil configured to be electrically energized to generate a magnetic field to attract said magnetic tip towards said electric coil; and a snare tool deployable from another lumen of said guide wire catheter, said snare having a loop that is expanded when said snare tool is deployed from said guide wire catheter and said loop is closed when said snare tool is retracted into said guide wire catheter, wherein said loop is configured to receive said magnetic tip when said electric coil is energized and is configured to retract to capture said received magnetic tip.

29. The kit according to claim 28, wherein: said kit includes a plurality of branch stent grafts and a plurality of guide wires.

30. The kit according to claim 29, wherein: said plurality of branch stent grafts includes two, three, or four or more branch stent grafts and said plurality of guide wires includes two, three, or four or more guide wires.

31. A method of assembling a branched stent graft system comprising: providing a stent graft according to claim 1; providing a branch stent graft having an elongate tubular body extending from a proximal end to a distal end, said branch stent having a flange extending from said proximal end; forming a through hole in a cell wall of at least one cell of said plurality of cells from within said lumen of said stent graft; introducing said branch stent graft through said lumen of said elongate stent graft to said through hole; inserting said distal end of said branch stent through said through hole; and sealing said flange to an interior surface of said cell zone wall surrounding said through hole.

32. The method according to claim 31, further comprising: prior to forming said through hole: inserting a guide wire through the main vessel and into a branch vessel; and deploying the provided stent graft into the main vessel while maintaining the guide wire outside the lumen of the main stent graft; introducing a steerable sheath surrounding a catheter through the lumen of the stent graft to the at least one cell; and deploying a hole forming tool from said catheter.

33. The method according to claim 32, wherein: said steerable sheath is moved in said lumen of said stent graft by following a path to said at least one cell that is parallel to said guide wire.

34. The method according to claim 33, wherein: a distal end of said steerable sheath is curved at an angle of over 90 degrees at the at least one cell.

35. The method according to claim 32, further comprising: extending a branch wire from said catheter through said through hole; guiding said branch wire into the branch vessel along said guide wire that is in the branch vessel; and guiding said branch stent graft through said through hole along said branch wire.

36. The method according to claim 32, further comprising: extending a ferromagnetic tool from said catheter surrounded by said sheath towards said through hole, said ferromagnetic tool having a magnetic tip; deploying a guide wire catheter to said though hole, said guide wire catheter being guided by said guide wire outside said lumen of said stent graft; deploying an electromagnetic tool from said guide wire catheter, said electromagnetic tool having an electric coil at a tip of said electromagnetic tool, wherein said electromagnetic coil is configured to be energized to generate a magnetic field; deploying a snare tool from said guide wire catheter, said snare tool having a loop that is in an expanded configuration when said snare is deployed from said guide wire catheter and has a contracted configuration when said snare is retracted into said guide wire catheter; energizing said electromagnetic coil to attract said magnetic tip to said electromagnetic coil and through said through hole and said loop of said snare tool; and capturing said magnetic tip with said snare tool by retracting said snare tool into said guide wire catheter; and guiding said captured magnetic tip with said guide wire catheter along said guide wire into said branch vessel. 27

37. The method according to claim 36, wherein: introducing said branch stent graft includes guiding said branch stent graft along a path defined by said steerable sheath and said ferromagnetic tool to said through hole.

38. The method according to claim 31, wherein: sealing said flange includes applying pressure to said flange from within said lumen of said stent graft.

39. The method according to claim 38, wherein: pressure is applied by inflating a balloon within said lumen of said stent graft and in engagement with said flange.

40. The method according to claim 31, wherein: said stent graft includes a stretch film wrapped around an outer surface of said cell zone wall, said stretch film having a plurality of film holes corresponding to said plurality of cells, each film hole centered with each corresponding cell, and wherein each film hole is undersized with respect to a size of said through hole, and wherein inserting said distal end of said branch stent includes inserting said distal end of said branch stent through said through hole as well as a corresponding one of the film holes aligned with the through hole, and sealing includes expanding said branch stent to deform said stretch film into sealing engagement about an outer surface of said body of said branch stent to form a fluid tight seal therebetween.