US20060247760A1 - Methods and apparatus for treatment of aneurysms adjacent branch arteries - Google Patents

Abstract

A polymer coating/ring is employed to aid in the sealing and connection of modular elements used in body flow lumens for the exclusion and bypass of diseased regions of the flow lumen, such as where aneurysm occurs adjacent to branching blood vessels.

Description

FIELD OF THE INVENTION
• The field of the invention is the treatment of vascular abnormalities. More particularly, the field of the invention is the treatment of vascular abnormalities by placing an excluding device in a blood vessel to exclude or bypass an abnormality, including placing such an excluding device in an area near one or more branch vessels so as to bypass the abnormality, but not occlude the branch vessel.
BACKGROUND OF THE INVENTION
• “Aortic aneurysm” is the term used to describe a condition where a segment of the aorta is dilated to a diameter greater than its original diameter. Aneurysms can occur in virtually any region of the vasculature including the aorta in the abdominal and thoracic regions. Aortic aneurysms are caused by hardening of the arteries (atherosclerosis), high blood pressure (hypertension), genetic disposition such as Marfan's Syndrome, trauma, or less common disorders. Atherosclerosis is the most common cause.
• Where dilation meets or exceeds 50% of the original aortic diameter, i.e., where the diameter of the aorta is 150% of the original or expected diameter, intervention generally is deemed necessary. Without intervention, the aneurysm may continue to expand, leading to the possibility of tearing or rupture of the aorta, and death. Intervention includes techniques such as replacement of the aorta with a synthetic lumen which is sewn to the two ends of the still viable aorta after the aneurysmal portion has been opened or surgically removed, or, less invasively, by the endovascular placement of an exclusion device such as a stent graft across the aneurysmal site. The stent graft is a tubular member designed to provide a conduit enabling blood flow through the aorta without allowing the systemic pressure of the blood to further stretch the aneurysm. To enable these conditions, the stent graft must extend across the weakened blood vessel wall so that the opposed ends of the stent graft engage and seal against healthy blood vessel tissue to either side of the aneurysm.
• A stent graft includes a stent framework (stent portion), which provides physical support of the stent graft in a tubular configuration once deployed at a vascular location, and a graft portion, comprising an excluding material, which is sewn or otherwise attached to the stent portion and which provides a relatively fluid-tight conduit for blood flow through the stent graft and past the aneurysm site. Insertion of a stent graft can be performed without a chest incision using specialized catheters that are introduced through arteries usually at a location in a leg adjacent the groin.
• The aorta has numerous arterial branches. For example, the arch of the thoracic aorta has three major branches, all of which arise from the convex upper surface of the arch and ascend through the superior thoracic aperture to the root of the neck. The proximity of an aneurysm to a branch artery may limit the use of an excluding device such as a tubular stent graft, as the main body or ends of the tubular stent graft may occlude or block the branch arteries due to the need to position the stent graft to seal against a healthy, i.e., undiseased or dilated portion of the artery wall. There may be an inadequate length of healthy tissue for the stent graft to seal against in the area between the aneurysmal region of the artery and the location of the branch arteries, or, even if the stent graft initially is located without blocking a branch artery, there still is a risk of migration of the exclusion device to a position where it may partially or fully block a branch artery, since aneurysms of the descending aorta commonly occur above and adjacent to the celiac trunk, superior mesenteric and renal arteries.
• Therefore, there is a desire in the art to achieve a greater success of aneurysm repair and healing, and in particular, mechanisms and methods to enable stent grafting or the placement of other exclusion devices adjacent to branch vessels in aneurysmal locations.
SUMMARY OF THE INVENTION
• Embodiments according to the present invention address aneurysm repair and in situ positional stability of a device used for aneurysm repair. Specifically, embodiments according to the present invention provide methods and apparatus for use in the treatment of aneurysms located near branch vessels, using modular, sectional-type stent grafts that exclude the aneurysmal region without blocking or otherwise impeding the flow of blood to branch arteries. Additionally, these modular stent grafts provide a tight seal between sections. Although the specification provides specific configurations for use in abdominal and thoracic locations, stent grafts according to the invention are readily applicable to uses in other aneurysmal locations where branch vessels or other flow lumen discontinuities are present. Stent graft features according to the invention can also be used in all modular components of a stent graft that do not necessarily relate to branch vessels, including junctions between main modular elements and other stent graft extensions such as cuffs.
• Thus, in one embodiment according to the invention there is provided a modular exclusion device useful for implantation in an aneurysmal site in a blood vessel having a branch vessel near the aneurysmal site comprising: a main body with at least one aperture; at least one insert with an insertion end, where a polymeric compound is disposed within the aperture of the main body, on the insertion end of the insert, or both within the aperture of the main body and on the insertion end of the insert, and where the polymeric compound comes into contact with both the aperture of the main body and the insertion end of the insert when the insertion end of the insert is disposed within the aperture of the main body. In addition, an embodiment provides a method of treating an aneurysm in a blood vessel having a branch vessel near the aneurysm, comprising deploying a modular exclusion device comprising a main body with at least one aperture; deploying at least one insert with an insertion end, where a polymeric compound is disposed within the aperture of the main body, on the insertion end of the insert or both within the aperture of the main body and on the insertion end of the insert, and where the polymeric compound comes into contact with both the aperture of the main body and the insertion end of the insert when the insertion end of the insert is disposed within the aperture of the main body.
BRIEF DESCRIPTION OF THE DRAWINGS
• A more particular description of the embodiments may be had by reference to the embodiments according to the invention described in the present specification and illustrated in the appended drawings.
• FIG. 1 is an artist's rendering of a cross section of an aorta showing an aneurysm near the thoracic aortic arch;
• FIG. 2A shows an exterior side view of the stent graft useful for excluding the aneurysm of the aorta shown inFIG. 1;
• FIG. 2B is a close-up of one stent graft aperture and an insert therefore;
• FIG. 2C is an exterior side view of the stent graft ofFIG. 2A, wherein the stent graft has been located over a guidewire used for guiding the stent graft, once loaded into a delivery device, to the aneurysmal location in the thoracic aortic arch ofFIG. 1;
• FIG. 2D is an exterior side view ofFIG. 2C, wherein the stent graft has been compressed for delivery into the delivery device;
• FIG. 3 is a cross sectional view of the aneurysmal aorta ofFIG. 1 showing the deployment of a stent graft, with the stent graft delivery device displayed in partial cutaway.
• FIG. 3A shows a cross section of the main portion of the stent graft installed, with a catheter tracking to deliver a branch insert;
• FIG. 4 is an exterior side view of the stent graft ofFIG. 2 shown deployed in the aneurysmal aorta ofFIG. 1 and further showing extension of the apertures and the inserts from the upper wall of the stent graft into the branch arteries of the aneurysmal aorta ofFIG. 1;
• FIG. 5 is an artist's rendering of a cross section of an aorta showing an aneurysm of the abdominal aorta;
• FIGS. 6A and 6B are exterior side views of a stent graft useful for excluding the aneurysm of an abdominal aorta as shown inFIG. 5;FIG. 6C shows the stent graft ofFIGS. 6A and 6B positioned in an abdominal aorta;
• FIG. 7A is an exterior side view of another stent graft useful for excluding the aneurysm of an abdominal aorta as shown inFIG. 5;FIG. 7B shows the stent graft ofFIG. 7A positioned in an abdominal aorta;
• FIGS. 8A and 8B are exterior side views of yet another stent graft useful for excluding the aneurysm of an abdominal aorta as shown inFIG. 5;FIG. 8C shows the stent graft ofFIGS. 8A and 8B positioned in an abdominal aorta;
• FIG. 9 is an exterior side view of another modular, multi-sectional stent graft useful for excluding the abdominal aortic aneurysm shown inFIG. 5;
• FIG. 10 is an artist's rendering of a cross section of a blood vessel showing an aneurysm in a branched portion of a blood vessel; and
• FIG. 11A is an exterior side view of two parts of a rotation cuff device useful for excluding the aneurysm of the vessel shown inFIG. 10;FIG. 11B is an exterior side view showing the two parts of the rotation cuff ofFIG. 11A assembled with portions of each cuff shown in phantom;FIG. 11C is an exterior side view of the assembled cuff positioned in the branched region of the vessel shown inFIG. 10.
DETAILED DESCRIPTION
• Reference now will be made to details of exemplary embodiments according to the invention. It is to be understood that the described embodiments are not intended to limit the invention solely and specifically to only these embodiments.
• Methods and apparatus for stabilizing and treating an aneurysm include deploying a modular, sectional exclusion device, such as a stent graft, in the flow lumen of a blood vessel to span the aneurysmal location and seal off the aneurysmal location of the blood vessel from further blood flow while acting as a conduit to direct blood flow past the aneurysmal site. In the case of an aneurysm near a branch artery, methods and apparatus for treatment include positioning a modular endovascular stent graft in the aneurysmal site, where the stent graft includes a main body with at least one aperture, and in some embodiments two or three or more apertures, where separate individual inserts are disposed within each aperture to extend sealingly into the exclusion device and sealingly into a branch artery. A polymeric compound is used on either the insert, within the aperture or both, to ensure a snug, well-sealed fit between the aperture in the main body and the insert.
• In addition to versatility in accommodating branch vessels, modular stents allow for in situ adjustment of insert lengths to accommodate different patient needs. Modular stent grafts are known in the art, and are disclosed in, inter alia, U.S. Pat. No. 6,129,756 to Kugler, et al.; U.S. Pat. No. 5,824,040 to Cox, et al.; U.S. Pat. No. 6,093,203 to Uflacker, et al.; U.S. Pat. No. 6,579,312 to Wilson, et al.; U.S. Pat. No. 5,906,641 to Thompson, et al.; and U.S. Pat. No. 5,855,598 to Pinchuk, et al., all of which are incorporated by reference in their entireties in for all purposes.
• Each of the apertures of the main body of the stent graft is alignable with, and extendable into, a branch artery to aid in maintaining alignment of the aperture with the branch artery for providing additional positional stability for the deployed stent graft. The stent graft excludes the weakened vessel wall at the aneurysmal site from further exposure to blood flowing through the aorta, but, as a result of the aperture, allows blood to flow from the aorta to the branch artery(ies), even where the main body of the stent graft extends across the branch artery(ies). Inserts are then provided to fit sealingly into each aperture and further extend sealingly into the branch vessels, thereby preventing leakage of blood from the branch arteries into the region between the stent graft and the weakened blood vessel wall at the aneurysmal location. A polymeric compound strengthens the seal between the main body of the stent graft and the insert.
• Referring initially toFIG. 1, there is shown an aneurysm of theabdominal aorta10, such that the aorta is enlarged at ananeurysmal location14 wherein theaorta wall12 is distended and stretched. Theaneurysmal location14 forms an aneurysmal bulge orsac18. If left untreated, the aneurysmal portion of theaorta wall12 may continue to deteriorate, weaken, and eventually tear or burst. Theaorta10 extends upwardly from the heart (not shown), such that at theaortic arch50, three branching arteries, thebrachiocephalic trunk56, the left commoncarotid artery54 and the leftsubclavian artery52, extend fromaorta10.
• FIG. 2A is an exterior side view of a modular stent graft that may be used to treat the aneurysm inFIG. 1 and that incorporates, as will be described further herein, a polymeric compound in one embodiment according to the present invention. There is shown generally a main body of thestent graft20 comprising a tubular stent frame (framework)22 and agraft material24 attached to thestent frame22 such as by sewing thegraft material24 to thestent frame22, which together form an integral tubular structure having a profile substantially mimicking that of a healthy thoracic aorta. In one aspect, thestent frame22 may be formed of a plurality of wires, each of the wires bent into a zig-zag configuration and joined at its opposed ends to form a continuous hoop. The individual wires are then interconnected by a plurality of spanning wires, which are crimped at their opposed ends which are crimped to adjacent formed wires to form the support structure of thestent frame22. This support structure is attached to thegraft material24, such as by sewing the two portions together, and then positioned in the aorta to push against theaorta wall12 and support thegraft material24 so as to enable thegraft material24 to seal against healthy portions of theaorta wall12 and to provide a conduit through which blood flows and bypasses theaneurysmal location14 of theaorta10.
• In the stent graft shown inFIG. 2A, there are three apertures (generically at60) extending from themain body21 of thestent graft20, specifically apertures62.64 and66, extending from the wall of the main body of thestent graft20. Referring back toFIG. 1, when thestent graft24 is deployed in theaorta10,aperture66 accommodates the exit of thebrachiocephalic trunk56 from theaortic arch50,aperture64 accommodates the exit of the left commoncarotid artery54 from theaortic arch50 andaperture62 accommodates the exit of the leftsubclavian artery52 from theaortic arch50. In addition to the brachiocephalic trunk, the carotid artery and the left subclavian artery, other branched vessels (not shown) may be present and would be accommodated by one or more apertures as appropriate.
• FIG. 2A also shows threeinserts72,74 and76, having bothstent frame22′ andgraft24′ components, i.e., each of theinserts72,74 and76 are configured with a stent frame sized to be slightly larger than the circumference of the branch artery into which it is inserted, and has a tubular length ofgraft24′ material sewn or otherwise affixed thereto.Insert76 is configured to be inserted intoaperture66 which accommodates the exit of thebrachiocephalic trunk56 from theaortic arch50 and which supports the vasculature thereof;insert74 is configured to be inserted intoaperture64 which accommodates the exit of the left commoncarotid artery54 from theaortic arch50 and which supports the vasculature thereof; and insert72 is configured to be inserted intoaperture62 which accommodates the exit of the leftsubclavian artery52 from theaortic arch50 and which supports the vasculature thereof.
• The materials making up the stent frame portion of the stent graft and/or insert(s) may be a metal, such as stainless steel, nitinol (NiTi) or tantalum (Ta), all known well in the art. In addition, various iron alloys such as iron platinum, iron palladium, iron nickel cobalt titanium, iron nickel carbon, iron manganese silicon, and iron manganese silicon chromium nickel. Generally the diameter of the metal wire/tube used for construction of the stent is between about 0.005 inches to about 0.02 inches. When nitinol is employed, the stent graft may have shape memory characteristics. While a braided construction of the stent frame is shown, this depiction is merely representative of any one of the numerous stent frame structures used to support stent grafts as is well known by persons skilled in the art.
• The material composing thegraft24 of thestent graft20 may be any biocompatible material that is mechanically stable in vivo, and is capable of preventing or substantially reducing the possibility of the passage or flow of blood or other body fluids there through. Typical materials forgraft24 include biocompatible plastics such as implantable quality woven polyester. Such polyester material may also include, therewith, components such as collagen, albumin, of an absorbable polymonomer or of a biocompatible fiber. Additionally, non-resorbable elastomers or polymers such as silicone, SBR, EPDM, butyl, polyisoprene, Nitril, Neoprene, nylon alloys and blends, poly(ethylene-vinyl-acetate) (EVA) copolymers, silicone rubber, polyamides (nylon 6,6), polyurethane, poly(ester urethanes), poly(ether urethanes), poly(ester-urea), polypropylene, polyethylene, polycarbonate, polytetrafluoroethelene, expanded polytetrafluoroethelene, polyethylene teraphthalate (Dacron) polypropylene and polyethylene copolymers.
• In the embodiments shown herein, where thestent graft20 further includes apertures such asapertures62,64 and66 which align with branch arteries adjacent to theaneurysmal site14, and also receives an insert such asinsert72,74 and76 in each of the apertures, the inserts, and optionally the region of theapertures62,64 and66 into which the inserts are received, may be formed of or coated with a non-resorbable polymer such as polymethylsiloxane, polydimethylsiloxane or polymethylphenylsiloxane or silicone. For example, each of theinserts72,74 and76 may comprise a stent graft type structure, onto which a non-resorbable polymer, including polyurethane, silicone, polymethylsiloxane, polydimethylsiloxane or polymethylphenylsiloxane are coated thereon. The coating can be accomplished by sewing or adhering strips of the polymer to the mating surfaces of the inserts and apertures, by spray coating, by dip coating or vapor coating the materials thereon. Additionally, the inserts, and/or the apertures may be formed of a compound material formed, such as, for example, by insert molding wherein the aperture (62,64 or66) portions of thestent graft20 are held in a mold and a polymer such as silicone is molded thereto. Where thestent frame22 portion of thestent graft20 is composed of a shape memory material, the material(s) selected to coat the apertures must also be able to withstand, without degradation of its mechanical properties which would render it incapable of sealing against itself, temperatures sufficiently low, on the order of the temperature of liquid nitrogen, to allow the tubular stent graft to be compressed into a small diameter structure for insertion into a delivery catheter as will be further described herein.
• In one aspect, the non-resorbable polymer may be silicon, which is dip coated or insert molded to appropriate portions where thestent graft20 and inserts72,74 and76 engage one another in intended sealing contact. The silicone may be, for example, simply adhered to thestent graft20 inner surfaces about the inner perimeter of theapertures60, such as by lowering or placing theapertures60 over a mandrel or rod having an as yet uncured, substantially viscous silicon located thereon. This could be performed, for example, by dipping the rod into a bath of uncured silicone, such that a film of silicone forms thereon, and mating the rod to the interior of the apertures. Likewise, the rod could be rolled over the exterior surface of the portion of theinserts72,74 and76 which are to be received in the apertures, and thus the silicone will become adhered to, and thus deployed on, the surface of theinserts72,74 and76. The silicone is then allowed to cure, either in air at atmospheric temperature and pressure conditions, or in an oven at elevated temperature.
• Thestent graft20 and inserts72,74 and76 ofFIG. 2A show two different paradigms for use of the polymer on the components for sealing of theinserts72,74 and76 to theapertures60.Insert76 andaperture66 are coated with the polymer entirely about the circumferential mating or contacting position of theinsert76 to theaperture66. In this case, thecoating65 extends entirely about the circumference of theinsert76 and from the end thereof which is received in theaperture66 by a distance equal to the length by which theinsert76 is received in theaperture66. Likewise, coating65′ is received inaperture66 substantially about its entire projected length. In contrast,apertures62 and64, and likewise inserts72 and74, demonstrate a different aspect, in which a continuous circumferential coating of the polymer is replaced by a series oflongitudinal stripes67 extending along the outer surface of theinserts72,74 andstripes67′ of the polymer extend longitudinally along the inner surface of the apertures (aperture projection or nozzles)62,64 into which theinserts72,74 are received. In this aspect, the polymer stripes reduce the bulk of material and the circumferential stiffness of the stent graft, by leaving open spaces of bare graft material between thelongitudinal stripes67. Thus, in one example, such a configuration provides an alternate back and forth folding pattern as the stent graft diameter is reduced to its compressed state for delivery within the delivery system. In such a pattern when folded (compressed), the longitudinal stripes are not in contact with any adjacent longitudinal stripes, but only with the bare graft or stent frame materials, so that premature melding of polymer stripes to one another does not occur to cause sticking between adjacent folds when the stent graft is deployed (expanded). In this aspect, theinserts72,74, when received in theirrespective apertures62,64, are configured and positioned such that a portion of the stripes on theinserts72,74 contacts a portion of the stripe on the aperture.
• The thickness of the graft material optionally is minimized to reduce the overall cross sectional thickness of thestent graft20 and thus the size of thestent graft20 as deployed in a delivery catheter. Generally, the graft material will be thinner than about 0.005 inch, and may be thinner than about 0.002 inch.
• In the embodiment of thestent graft20 shown inFIG. 2A, the ends of thegraft material24 extend beyond the marginal edges of thestent frame22, i.e., thegraft material24 extends axially beyond the opposed generally circular ends of thestent frame22 to form opposed ends26,28 of thestent graft20. This arrangement is one of various arrangements of the position of thegraft20 portion with respect to thestent22, as in other embodiments according to the present invention the ends of thegraft portion24 are coincident with the opposed ends of thestent frame22 or the ends of thestent frame22 may extend beyond the marginal ends of thegraft portion24. The ends of thegraft portion24 of thestent graft20 are preferably configured to prevent fraying, which may be accomplished by heat fusion or binding of the edge of thegraft portion24 or by folding the end of thegraft portion24 back upon itself and sewing it to thestent frame22 or to itself. Also, thegraft portion24 may be located on the interior of thestent frame22, on the exterior of thestent frame22, or thegraft portion24 may be located in the interstitial spaces between the portions or sections of the stent framework (shown as a braided pattern in the Figures herein). Thegraft portion24 may include more than one layer or ply. Thegraft24 preferably is sufficiently non-porous to prevent blood from leaking into the aneurysmal sac18 (FIG. 1). In some embodiments, the material forming thegraft portion24 may include a coating of non-porous material over one or more porous layers. Thegraft portion24 is attached thestent frame22, typically as by sewing thegraft24 to thestent frame22, but the use of an adhesive, heat bonding of thegraft24 to thestent frame22, or other methodologies are specifically considered acceptable so long as the integrity of the connection of thegraft24 to thestent frame22 is maintained.
• FIG. 2B is a close up of oneexample aperture66′ of the type shown in the group ofapertures60 formed on themain body21 of thestent graft20, and an example of aninsert76′ of the plurality ofinserts72,74 and76 fromFIG. 2A. In this embodiment, the inserts such asinsert76 shown inFIG. 2A are not coated with a polymer or other sealing and securing material, but instead aring82 of the sealing or securing material such as silicone is sewn or otherwise attached to the insert, and likewise aring82′ of the sealing or securing material is secured within the inner circumference of theaperture66′ into which insert76′ is to be deployed. As shown inFIG. 2B, theaperture66′ (as well as similar adjacent apertures (not shown) likeapertures62,64) preferably have aneck portion80 which extends outwardly, in a tubular cross section, from themain body21′ of thestent graft20′, and includes aring82′ formed thereon in the manner previously discussed. Theinsert76′ (and likewise adjacent inserts) is secured within theaperture66′ by friction between the conformable mating polymeric surfaces. In addition, where the material of therings82,82′ is a polymer having a low glass transition temperature, the area of contact between twoadjacent rings82,82′ will fuse together over time in situ (as it will in the other examples where polymer to polymer contact is described). Additionally, a portion of theinsert76 extends outwardly from themain body21′ of the stent graft beyond the end of theneck portion80 of theaperture66′ and is positioned against the wall of the branch vessel into which it is deployed, preventing leakage of blood or other fluids past the apertures (e.g.,62,64 and66) of thestent graft20, while allowing blood to flow through the inner tubular portion of both the apertures (e.g.,62,64 and66) and the inserts (e.g.,72,74 and76).
• To deploy thestent graft20 endovascularly, thestent graft20 must be configured to fit within a tubular catheter. To accomplish this, themain body21 of thestent graft20 is first compressed, as shown inFIG. 2C, and then further folded or compressed to the configuration (diameter) ofFIG. 2D at which time it may be inserted into the end of a catheter such ascatheter30 shown inFIG. 3. During the compressing of thestent graft20, aguide wire catheter33 may first be extended therethrough, as is also shown inFIG. 2C. Theguidewire catheter33 is a hollow tube through which a guidewire31 (FIG. 3) is passed, and supports, at its distal end thereof, an insertion end32 (catheter tip) through which guidewire31 likewise extends (FIG. 3). For deployment of thestent graft20, theguidewire catheter33 extends within the length of thetubular catheter30 such that its distal end is attached to theinsertion end32 and its proximal end is manipulable by a technician or surgeon to position the distal end in relative proximity of the deployment location. Where thestent frame22 portion of themain body21 of thestent graft20 is configured of a shape memory material, such as nitinol, themain body21 can be first cooled to a very low temperature, such as by using sprayed bursts of liquid nitrogen which depending on the composition of the nitinol can make the nitinol plastically deformable an easier to load, before it is compressed (as shown inFIGS. 2C and 2D.) Where thestent portion22 is comprised of a non-shape memory material, an inflation device such as aballoon34 on theguidewire catheter33 connected to an end of aninflation lumen38 extending along theguidewire catheter33 is first located inside of the tubular shape of themain body21, onto which the stent graft can be compressed. Likewise, inserts72,74 and76 can be compressed and placed in separate catheters, one such catheter shown ascatheter30′ inFIG. 3A. Each insert may be located in a single catheter, or all of the inserts necessary to deploy one into each of theapertures60 may be deployed in a single catheter, with one insert closest to the open end thereof, and the next one(s) stacked therebehind. Additionally, where the inserts are configured incorporating a non-shape memory alloy as the stent material, a balloon must be first placed inside the tubular volume before compressing it. This can be unnecessary where the insert is self expanding. It is also possible that the insert is compressed over the smaller balloon and is able to adhere to the balloon without the use of an outer sheath.
• Referring still toFIG. 3, the initial deployment of thestent graft20 into the thoracic arch into ananeurysmal location14 spanning position is shown. Prior to the deployment of thestent graft20, aguide wire31 is extended from a remote blood vessel incision site leading to the arch50, and through the arch50, such that the inserted end thereof extends past the intended location of the deployedstent graft20. To position and properly locate thestent graft20 in a spanning, sealed position in theaneurysmal location14, thestent graft20 is introduced through an artery, such as the femoral artery (not shown), by inserting thecatheter30 into the artery through an incision in the leg. Thecatheter30 preferably includes an outer sheath portion enclosing a collapsed orcompressed stent graft20 held within a distal end of thesheath30 which is introduced into the patient's artery and from which thestent graft20 is deployed. A proximal end of the catheter (not shown) is maintained external to the body and is manipulated to axially and rotationally position catheter within theaorta10. At least onepush rod36 can extend within thecatheter30, from a position adjacent to the distal end of thestent graft20 within the hollow portion of thecatheter30, to a position beyond the proximal end of thecatheter30. Additionally, where a balloon is employed in the deployment of the catheter, alumen38 capable of introducing saline extends from aballoon34 within thestent graft20 to a position beyond the proximal end of thecatheter30 where it is connectable to an inflation device.Catheter30 and any other catheters required for deployment typically carry radiological markers on their outer surface adjacent thedeployment end38, to enable the surgeon deploying the stent graft to determine the position of the catheter in the body, such as by fluoroscopic or other means. Additionally, thestent graft20 has radiological markers thereon to enable determination of the position and rotational orientation thereof at the aneurysmal location.
• In deploying thestent graft20,catheter30 is tracked through the patients' artery, until the end thereof is disposed in the arch physically beyond theaneurysm location14. Thepush rod36 which is located against the distal end of thestent graft20 withincatheter30, and holds thestent graft20 stationary as the tubular sheath of thecatheter30, is withdrawn or retracted with respect to theaneurysmal location14. As the sheath retracts, thestent graft20 is progressively released from the sheath in a position spanning across theaneurysmal location14 of the aorta. As the catheter sheath is withdrawn with thepush rod36 held stationary, and as the deployment of thestent graft20 is beginning, thecatheter30 may be rotated to ensure that themain body21 of thestent graft20 deploys with theapertures62,64 and66 in alignment with thebranch arteries52,54 and56.
• Thestent graft apertures62,64, and66 are, when thestent graft20 is properly aligned in theaorta10 andarch50, aligned with thebranch arteries52,54 and56, and expanded to extend outwardly from the wall of thestent graft20. In the configuration of the embodiment of the stent graft inFIGS. 2A and 3, three branch arteries must be spanned and thus threeapertures60 are provided. Alternatively, where the size and location of theaneurysmal sac18 enables a shorter length of stent graft to ensure sufficient sealing of the stent graft against the wall of the aorta, or, where the aneurysmal sac is more remotely located from the branch artery locations, the stent graft may be deployed with fewer openings therein, and anaperture60 need only be located in each of those openings. After themain body21 of thestent graft20 is deployed, the balloon, where used, is deflated and withdrawn along with thecatheter30.
• A separate catheter, e.g.,30′, may be used to deploy eachinsert72,74 and76 into eachseparate aperture62,64 and66. This is provided by deploying additional catheters in a number equal to the number of inserts used, through the artery and within thestent graft20, and extending each catheter along a guidewire into individualstent graft branches60. To direct the catheters into theappropriate apertures60, aguide wire31′ is first deployed and guided into and past the appropriate aperture and a further distance along theappropriate branch artery52,54 or56. The catheter is positioned such that the distal end of the catheter is disposed inside of the aperture and branch vessel where the insert in the branch vessel will be located. As with the deployment of themain body21, the sheath of thecatheter30′, with a push rod (not shown) positioned against aninsert72,74 or76, is withdrawn and theinsert72,74 or76 deploys, with the shape memory material expanding to the expanded diameter of the tubular section of theinsert72,74 or76, with the outer surface thereof engaged with the inner surface of the aperture to sealingly secure theinsert72,74 or76 therein by an interference or friction fit, with the portion extending outwardly therefrom in sealing engagement with the adjacent wall of theparticular branch vessel50 into which it is deployed. Where shape memory material is not used, a balloon is positioned within theinsert72,74 or76, to cause its expansion. This procedure is repeated, with repositioning of the guidewire and redeployment of thecatheter30′, until all of the needed inserts are deployed. Once the stent graftmain body21 and inserts72,74 and76 are deployed, all balloons (where needed) are deflated, the catheters and guidewires are withdrawn, and the artery and leg incision(s) are closed. Thestent graft20 and inserts72,74 and76 are thus positioned, spanning the branch arteries without blocking them. Methods and apparatus for the deployment of sectional stent grafts are also disclosed in U.S. Pat. No. 5,683,451 to Lenker, et al.; U.S. Pat. No. 5,713,917 to Leonhardt, et al.; and U.S. Pat. No. 5,984,955 to Wisselink, et al., all of which are incorporated by reference in their entireties in for all purposes.
• Once theinserts72,74 and76 are positioned in therespective apertures62,64 and66, the contacting surfaces of the polymer disposed on both theapertures62,64 and66 and theinserts72,74 and76 provide both sealing of the insert-aperture interface, but likewise provide increased friction due to the polymer to prevent the movement of the inserts with respect to the apertures. Over time, the interface of the (polymer) sealing materials may meld together to form a continuous adhering material between the insert and the aperture. However, the ability of these materials to meld together is, in part, based upon their tackiness, i.e., the ability or desire of the material to stick to materials into which it comes in contact. This property may affect the ability to deploy theapertures62,64 and66 and theinserts72,74 and76, as the sealing and securing material thereon, for example thecoating65 or65′, may come into contact with itself during the compressing of thestent graft20 or theinserts72,74 and76 for the placement thereof into catheters. To minimize the risk that the apertures of thestent graft20 or theinserts72,74 and76 will become adhered together in the collapsed state, three construction and/or deployment paradigms may be used: Firstly, a balloon may be provided within the envelope of each of theapertures62,64 and66 and inserts72,74 and76, such that the inflation thereof, in situ, will overcome any sticking of the material65 to itself. Secondly, the sealing and securing material may be comprised asstripes67,67′, as shown inFIG. 2A, such that upon compressing of thestent graft20 or theinserts72,74 and76, thestripes67,67′ of sealing and securingmaterial contact stent22 orgraft24 material, and not anadjacent stripe67,67′. Thirdly, thecoating65,65′ may, prior to the compressing and configuring of thestent graft20 and theinserts72,74 and76, be covered with a release material, such as a thin sheet of PTFE or FEP material, which material is adhered likewise to a wire or other catheter deployable member which can be pulled outwardly of the patient, during the deployment of thestent graft20 or inserts72,74 and76, to pull the sheet off of the polymer prior to the contact of the polymer carrying portion of theinsert72,74 or76 with itsappropriate aperture62,64 or66. Thus, the stickiness or tackiness of the polymer may be used to help secure and seal or meld the insert and aperture together, while theinserts72,74 and76 andapertures62,64 and66 are expandable in situ.
• Referring toFIG. 4, once deployed, thestent graft20 is intended to provide a flow conduit across theaneurysmal sac18 of theaorta10, and to seal off theaneurysmal sac18 from further blood flow. Thestent graft20 is sized so that, upon deployment in theaorta10, the diameter of thestent graft20 is slightly larger than the normal, healthy diameter of theaorta10 so that the opposed ends26,28 of thestent graft20 are in apposition with the inner wall of theaorta10. Further, thestent graft20 is long enough to span theaneurysmal sac18 of theaorta10 and sealingly contact theaorta wall12 on opposite sides of theaneurysmal sac18. Such sealing includes the region of theaorta wall12 between thebranch arteries52,54 and56, as well as regions distal and proximal from theaneurysmal region18. To enable sealing by thestent graft20, the stent graft includes a circumferential wall, which, at opposed ends26 and28, is engageable against theinner wall12 of theaorta10 to effect sealing and prevent, when properly deployed, blood flow into theaneurysmal sac18 of theaorta10. Additionally, theinserts72,74 and76 extend into thebranch arteries52,54 and56, providing an extended conduit for blood flow thereby excluding blood from the region of the branch vessels where vessel delamination (dissection) may occur.
• WhereFIG. 1 shows an aneurysm near the thoracic aortic arch,FIG. 5 is an artist's rendering of an aorta showing an aneurysm in the abdominal aorta.FIG. 5 shows anaorta110 with an aortic wall at112. There is an aneurysmal site at114, defining an aneurysmal sac at118. Renal arteries are seen at116, the right iliac artery is seen at119 and the left iliac artery is seen at117.
• FIGS. 6A and 6B are schematic exterior side views of a stent graft useful for excluding an aneurysm of the aorta shown inFIG. 5.FIG. 6A shows a main body of thestent graft120 generally, with astent frame122 andgraft portion124. In addition,stent graft120 has a secondbranch insertion site125, as well as apolymeric compound182 such as a polymeric compound such as that used in conjunction with the inserts and apertures of the embodiment shown inFIGS. 2, 3 and4 disposed inside the insertion site (shown in phantom). Also inFIG. 6A, there is aninsert170 having aninsertion end171, likewise comprised of astent frame portion122 andgraft portion124. Oninsert170, there is disposed, at180, a polymeric compound such as that used in conjunction with the inserts and apertures of the embodiment shown inFIGS. 2, 3 and4.
• FIG. 6B shows the main body of thestent graft120 and insert170 ofFIG. 6A assembled. InFIG. 6B,insertion end171 ofinsert170 is disposed within the main body of thestent graft120, such that thepolymeric compounds180,182 on theinsert170 and the main body of thestent graft120 engage against one another.
• FIG. 6C shows the assembled stent graft and insert fromFIG. 6B positioned within an abdominal aortal region ofFIG. 6A. Theaorta110 shows an aorta wall at112, an aneurysmal region at114 and an aneurysmal sac at118. The renal arteries are seen at116, the left iliac artery is seen at117 and the right iliac artery is seen at119.Stent graft120 and insert170 are shown withstent portions122 andgraft portions124. The insertion end ofinsert170 is shown at171. Thestent graft120 and insert170 are deployed similar to howstent graft20 shown inFIGS. 2, 3 and4 is deployed, i.e., the mainbody stent graft120 is tracked, in a catheter, Up the rightiliac artery119, and deployed from the catheter and positioned as shown inFIG. 6C. Theinsert170, which forms the contralateral leg of the assembled stent graft, is tracked in a catheter up the leftiliac artery117, such that the end thereof having thepolymeric compound180 thereof is inserted into theopening125 of thestent graft120, and then inflated or otherwise restored to its free state such thatpolymer portions180 and182 contact one another.
• FIG. 7A is an exterior side view of an upper portion of an example of a custom configured stent graft useful for excluding an aneurysm of an aorta as shown inFIG. 5.FIG. 7A shows a main body of astent graft120′ generally, with stent frame/support portions122′ andgraft portions124′. In addition,stent graft120′ hasbranch insertion sites125aand125bthat extend radially outwardly from thestent graft120′ and which align with the renal arteries (not shown) when thestent graft120′ is deployed.Polymeric compound182, such as the polymeric compound used in conjunction with the inserts and apertures of the embodiment shown inFIGS. 2, 3 and4, is disposed inside theinsertion sites125aand125b. Also shown inFIG. 7A, areinserts170aand170bhaving mating ends171aand171b, on which is disposed the polymeric compound at180. The embodiment of thestent graft120′ ofFIG. 7A further includes two fenestration extensions at127a,127bwith thepolymeric compound184 disposed on the outer surface thereof. The fenestration extensions accommodate the celiac trunk and the superior mesenteric artery (not shown) when thestent graft120′ is deployed.
• FIG. 7B shows the upper portion of thestent graft120′ fromFIG. 7A assembled with two additional portions positioned within an abdominal aortal region. Theaorta110 has an aorta wall at112, an aneurysmal region at114 and an aneurysmal sac at118. Renal arteries are seen at116, the left iliac artery is seen at117 and the right iliac artery is seen at119. Thestent graft120′ consists of five portions: anupper portion121 along withinserts170aand170bseen inFIG. 7B, as well asinserts170cattached to the open lower end ofupper portion121 and including a leg which accommodates rightiliac artery119, and aninsert170dwhich forms a leg and extends from an opening in theinsert170cinto sealing engagement with the leftiliac artery117.Inserts170a,170b,170cand170deach have insertion ends171a,171b,171cand171d, respectively, with the polymeric compound disposed thereon.
• In addition,FIG. 7B showsfenestration extensions127a,127bfromFIG. 7A.Fenestration extension127aaccommodates the superior mesentery artery (not shown), andfenestration extension127baccommodates the celiac trunk (not shown). Polymeric compound184aand184bis disposed on the outer surface of the fenestration extension to provide enhanced sealing of the fenestration extension with the branch arteries.
• FIGS. 8A and 8B are exterior side views of yet another configuration of stent graft useful for excluding the abdominal aorta shown inFIG. 5.FIG. 8A shows amain body120″ of a stent graft and aninsert170″. Again, both themain body120″ of the stent graft and insert170″ have stent portions at122″ and graft portions at124″. Themain body120 shows aninsertion site125 forinsert170″ as well aspolymeric compound182″, a polymeric compound such as that used in conjunction with the inserts and apertures of the embodiment shown inFIGS. 2, 3 and4, disposed within the inside rim of the insertion site.Insert170″ shows an insertion end at171″ as well as the polymeric compound at180″ shown applied around the insertion end.FIG. 8B shows themain body120″ of the stent graft and theinsert170″ ofFIG. 8A assembled. Again,stent frame122″ andgraft124″ portions are seen on both themain body120″ of the stent graft and theinsert170″. In addition, a portion of theinsert170″ is shown inphantom178″ disposed within thestent graft120.Polymeric compounds180 and182 are seen in phantom as well.
• FIG. 8C shows the assembled stent graft/insert combination ofFIG. 8B positioned within an abdominal aneurysm. Again, an aorta is seen at110, an aortal wall is seen at112, an aneurysmal region is seen at118 and an aneurysmal sac is seen at118. Renal arteries are shown at116, the left iliac artery is shown at117 and the right iliac artery is shown at119.Main body120″ of stent graft and insert170″ are also shown.
• FIG. 9 is an exterior side view of yet another stent graft useful for excluding the aneurysm of the abdominal aorta shown inFIG. 5.FIG. 9 shows a four-piece modular stent graft, with a main body at120′″ and inserts at170a′″,170b′″ and170c′″.Stent122′″ andgraft124′″ portions are shown on each of the four modular pieces.Insertion end171a′″ ofinsert170a′″ is shown, as isinsertion end171b′″ ofinsert170b′″ andinsertion end171c′″ ofinsert170c′″. Polymeric compound, a polymeric compound such as that used in conjunction with the inserts and apertures of the embodiment shown inFIGS. 2, 3 and4, is shown disposed on the inserts at180a′″,180b′″ and180c′″. In addition, polymeric compound such as silicone is shown disposed within stent graftmain body120′″ in phantom at182a′″,182b′″ and182c′″.
• FIG. 10 is an artist's rendering of a blood vessel showing an aneurysm adjacent a branch portion of the vessel.FIG. 10 shows an aorta at210, having aortal branches at211. The aortal wall is seen at212, the aneurysmal site is seen at214 and the aneurysmal sac is seen at218.
• FIG. 11A is an exterior side view of two parts of a rotation cuff device useful for excluding the aneurysm of the vessel shown inFIG. 10. Anouter cuff290 has a polymeric compound (such as that used in conjunction with the inserts and apertures of the embodiment shown inFIGS. 2, 3 and4) on various portion of the inner surface. Polymer coating is applied to at least one of the several areas shown. Generally there is continuous uninterrupted layer covering the coating area, though a striped coating configuration (as discussed above) can also be used. The coating area extends from the edge of the circular aperture (branch) or rectangular aperture outwardly from the opening and provides at least a minimum width contact area for the polymeric compound. While polymeric coatings are here shown on both pieces (outside of the inner one and on the inside of the outer one around both sets of openings), the polymeric coating can be configured with less initially coated area, such that the parts are configured to have a polymer coating in the space between layers around each branch related opening, when assembled. In this embodiment, edges of the polymer covered areas (coatings) on the inside surface are shown by dashed lines on theouter cuff290 atopening294.Opening294 accommodates theinner cuff aperture273. Theinsert cuff270, having an insert aperture at273 and theinsert aperture284 both have apolymeric compound area280 disposed around their edge as shown by the cross hatched area. While rectangular shaped areas for the polymer are shown, other geometric shapes which provide an edge sealing zone or continuous seal completely around the opening can be used.Opening284 accommodates theouter cuff aperture293.
• FIG. 11B is an exterior side view showing the twoparts290,270 of the rotation cuff ofFIG. 11A assembled. A portion of theinner cuff270 is seen throughopening294. The outer cuff aperture is seen at293 and the inner cuff aperture is seen at273. Areas having polymeric compound coatings are shown in dashed and cross hatched lines,293′ and273′ aroundouter cuff aperture293 andinner cuff aperture273.
• FIG. 11C is an exterior side of the assembled cuff ofFIG. 11B positioned in the branched vessel region shown inFIG. 10. The aorta is seen at210, the aortal wall is seen at212, the aneurysmal region is shown at214 and the aneurysmal sac is shown at218. Branched arteries are seen at216. The assembled cuff device is seen at300, withouter cuff aperture293 andinner cuff aperture273 shown.
• The stent grafts and cuffs according to the present invention may, optionally, deliver a therapeutic agent by way of a coating on the stent and/or graft material. In such an embodiment, the coating compound is adapted to exhibit a combination of physical characteristics such as biocompatibility, and, in some embodiments, biodegradability and bio-absorbability, while serving as a delivery vehicle for release of one or more therapeutic agents that aid in the treatment of aneurysmal or atherosclerotic tissue.
• In selecting an appropriate therapeutic agent or agents, one objective is to protect the aneurysmal blood vessel from further destruction. Another objective is to promote healing. Generally, aneurysm results from the invasion of the cell wall by inflammatory agents that cause the release of elastin and collagen attacking proteins that for unknown reasons begin to congregate at certain blood vessel sites. Attack of the blood vessel structure causes further inflammation and cyclically the release of more of these elastin and collagen attacking proteins. Inflammation, the elastin and collagen attacking proteins, and the resulting breakdown of tissue, are leading causes of aneurysm formation.
• Therapeutic agents useful in embodiments of the present invention include matrix metalloproteinase (MMP) inhibitors, which have been shown in some cases to reduce such elastin and collagen attacking proteins directly or in other cases indirectly by interfering with a precursor compound needed to synthesize the MMP's. Another class of agents, non-steroidal anti-inflammatory drugs (NSAIDs), has demonstrated anti-inflammatory qualities that reduce inflammation at the aneurysmal site, as well as an ability to block MMP-9 formation. Cyclooxygenase-2 or “COX-2” inhibitors also suppress MMP-9 formation. In addition, anti-adhesion molecules, such as anti-CD18 monoclonal antibody, limit the capability of leukocytes that may have taken up MMP-9 to attach to the blood vessel wall, thereby preventing MMP-9 from having the opportunity to attack the blood vessel extracellular matrix. Other therapeutic agents contemplated to be used to inhibit MMP-9 and possibly MMP-2 are tetracycline and related tetracycline-derivative compounds.
• Steroidal anti-inflammatory drugs such as dexamethasone, beclomethasone and the like may be used to reduce inflammation. Another class of therapeutic agent that finds utility in inhibiting the progression of or inducing the regression of a pre-existing aneurysm is beta blockers or beta adrenergic blocking agents. In addition to therapeutic agents that inhibit elastases or reduce inflammation are agents that inhibit formation of angiotensin II, known as angiotensin converting enzyme (ACE) inhibitors. ACE inhibitors are known to alter vascular wall remodeling, and are used widely in the treatment of hypertension, congestive heart failure, and other cardiovascular disorders vascular wall injury.
• The maximal dosage of the therapeutic to be administered is the highest dosage that effectively inhibits elastolytic, inflammatory or other aneurysmal activity, but does not cause undesirable or intolerable side effects. The dosage of the therapeutic agent or agents used will vary depending on properties of the stent, graft or coating material, including its time-release properties, whether the composition of the other components, and other properties. Also, the dosage of the therapeutic agent or agents used will vary depending on the potency, pathways of metabolism, extent of absorption, half-life and mechanisms of elimination of the therapeutic agent itself. In any event, the practitioner is guided by skill and knowledge in the field, and embodiments according to the present invention include without limitation dosages that are effective to achieve the described phenomena.
• While the present invention has been described with reference to specific embodiments, it should be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the true spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation, material or process to the objective, spirit and scope of the present invention. All such modifications are intended to be within the scope of the invention.
• All references cited herein are to aid in the understanding of the invention, and are incorporated in their entireties for all purposes.

Claims (22)

1. A modular exclusion device useful for implantation in an aneurysmal site in a blood vessel comprising: a main body with at least one aperture; at least one insert with an insertion end, wherein the insertion end of the insert is disposed within the aperture of the main body, and wherein a polymeric compound is disposed within the aperture of the main body.

2. The modular exclusion device ofclaim 1, wherein the polymeric compound is located on the insertion end of the insert or both within the aperture of the main body or on the insertion end of the insert.

3. The modular exclusion device ofclaim 1, wherein the polymeric compound is disposed on the insertion end of the insert.

4. The modular exclusion device ofclaim 1, wherein the polymeric compound is disposed in the aperture of the main body.

5. The modular exclusion device ofclaim 1, wherein the polymeric compound is disposed on both the insertion end of the insert and the insertion aperture of the main body.

6. The modular exclusion device ofclaim 1, wherein the polymeric compound is a silicone or a polyurethane.

7. The modular exclusion device ofclaim 5, wherein the silicone is polymethylsiloxane, polydimethylsiloxane or polymethylphenylsiloxane.

8. The modular exclusion device ofclaim 1, wherein the aneurysmal site is the thoracic aorta, the main body has three apertures and there are three inserts.

9. The modular exclusion device ofclaim 1, wherein the aneurysmal site is the abdominal aorta, the main body has two apertures and there are two inserts.

10. The modular exclusion device ofclaim 1, wherein the aneurysmal site is the abdominal aorta, the main body has two apertures, and there is one insert.

11. The modular exclusion device ofclaim 1, wherein the main body further comprises at least one fenestration.

12. The modular exclusion device ofclaim 10, wherein there is polymeric compound disposed on an outer surface of the main body substantially surrounding the at least one fenestration.

13. The modular exclusion device ofclaim 10, comprising a main body, a first insert to accommodate a first renal artery, a second insert to accommodate a second renal artery, a first fenestration to accommodate a superior mesentery artery and a second fenestration to accommodate a celiac trunk.

14. The modular exclusion device ofclaim 1, comprising a main body, and an insert to accommodate an iliac artery.

15. The modular exclusion device ofclaim 1, comprising a main body, a first insert to accommodate a brachiocephalic trunk, a second insert to accommodate a left common carotid artery, and a third insert to accommodate a left subclavian artery.

16. A modular exclusion device useful for implantation in an aneurysmal site in a blood vessel comprising: a main body with at least one fenestration, wherein a polymeric compound is disposed on an outer surface of the main body substantially surrounding the at least one fenestration.

17. The modular exclusion device ofclaim 15, comprising a main body, a first fenestration to accommodate a first renal artery, a second fenestration to accommodate a second renal artery, a third fenestration to accommodate a superior mesentery artery and a fourth fenestration to accommodate a celiac trunk.

18. The modular exclusion device ofclaim 15, comprising a main body, a first fenestration to accommodate a brachiocephalic trunk, a second fenestration to accommodate a left common carotid artery, and a third fenestration to accommodate a left subclavian artery.

19. A method of excluding a site of an aneurysm from blood flow comprising deploying a modular exclusion device at the site, wherein the modular exclusion device useful comprises a main body with at least one aperture; at least one insert with an insertion end, wherein the insertion end of the insert is disposed within the aperture of the main body, and wherein a polymeric compound is disposed within the aperture of the main body, on the insertion end of the insert or both within the aperture of the main body or on the insertion end of the insert.

20. A method of excluding a site of an aneurysm from blood flow comprising deploying a modular exclusion device at the site, wherein the modular exclusion device useful comprises a main body with at least one fenestration, wherein a polymeric compound is disposed on an outer surface of the main body substantially surrounding the at least one fenestration.

21. A modular exclusion device useful for implantation in an aneurysmal site in a blood vessel comprising: an outer cuff having an outer surface and an inner surface and at least one aperture; an inner cuff disposed with the outer cuff, wherein the inner cuff has an inner surface and an outer surface and at least one aperture aligned with the at least aperture of the outer cuff; and wherein a polymeric compound is disposed on the inner surface of the outer cuff, the outer surface of the inner cuff or both the inner surface of the outer cuff and the outer surface of the inner cuff.

22. The modular exclusion device ofclaim 1, comprising a main body and an insert to a hypogastric artery.

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