Patent Description:
The use of endovascular procedures has been established as a minimally invasive technique to deliver a variety of clinical treatments in a patient's vasculature. A stent graft is an implantable device made of a tube-shaped surgical graft covering and an expanding or self-expanding frame. The stent graft is placed inside a blood vessel to bridge, for example, an aneurismal, dissected, or other diseased or torn segment of the blood vessel, and, thereby, exclude the hemodynamic pressures of blood flow from the diseased segment of the blood vessel.

Depending on the region of the aorta involved, the aneurysm may extend into areas having vessel bifurcations or segments of the aorta from which smaller "branch" arteries extend. For example, thoracic aortic aneurysms can include aneurysms present in the ascending thoracic aorta, the aortic arch, and/or branch arteries that emanate therefrom, such as the left subclavian, left common carotid, or the brachiocephalic arteries. In some cases, a branched stent graft can be used to treat such aneurysms. For example, a branched stent graft can be deployed in the main vessel (e.g., aortic arch) with a coupling extending therefrom and toward or into the branched artery (e.g., left subclavian), and a supplemental, secondary stent graft can be deployed in the branched artery and connected to the coupling. <CIT> describes a stent graft tapered spring. <CIT> describes an endovascular stent-graft with fatigue-resistant lateral tube.

In an embodiment according to the invention, a stent graft includes a main body extending along a longitudinal axis when in a preinstalled configuration prior to insertion into a body of a patient, the main body extending between a proximal end and a distal end thereof. The stent graft also includes a mobile external coupling extending away from the main body and configured to align with a secondary blood vessel within the body to provide access thereto. The main body includes a plurality of stents extending thereabout, the plurality of stents including (i) a first bracketing stent extending about a proximal side of the mobile external coupling, and (ii) a second bracketing stent located adjacent the first bracketing stent and extending about a distal side of the mobile external coupling. The first bracketing stent includes a plurality of peaks that are aligned along a first axis, and the second bracketing stent includes a plurality of peaks that are aligned along a second axis, wherein the first and second axes diverge from one another in a circumferential direction toward the mobile external coupling.

In an embodiment, a stent graft includes a main body extending along a longitudinal axis when in a preinstalled configuration prior to insertion into a body of a patient, the main body extending between a proximal end and a distal end thereof. The stent graft also includes a mobile external coupling extending away from the main body and configured to align with a secondary blood vessel within the body to provide access thereto, wherein the mobile external coupling includes an opening at an end thereof located away from the main body. The main body includes a plurality of stents extending thereabout, with the plurality of stents including (i) a first bracketing stent extending about a proximal side of the mobile external coupling, and (ii) a second bracketing stent located adjacent the first bracketing stent and extending about a distal side of the mobile external coupling. The first bracketing stent includes a plurality of peaks that are aligned along a first axis, and the second bracketing stent includes a plurality of peaks that are aligned along a second axis. The second axis does not intersect the opening of the mobile external coupling.

In an embodiment, a stent graft includes a main body extending along a longitudinal axis when in a preinstalled configuration prior to insertion into a body of a patient, the main body extending between a proximal end and a distal end thereof. The stent graft also includes a mobile external coupling extending away from the main body and configured to align with a secondary blood vessel within the body to provide access thereto. The main body includes a plurality of stents extending thereabout, the plurality of stents including (i) a first bracketing stent extending about a proximal side of the mobile external coupling, (ii) a second bracketing stent located adjacent the first bracketing stent and extending about a distal side of the mobile external coupling, (iii) a support stent located longitudinally between the first bracketing stent and the proximal end of the main body, and (iv) a proximal stent that is the proximal-most stent of the stent graft and located adjacent the support stent. A portion of the support stent and a portion of the proximal stent extend longitudinal beyond the proximal end of the main body.

Embodiments of the present disclosure are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments can take various and alternative forms. The figures are not necessarily to scale; some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the embodiments. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures can be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations.

Directional terms used herein are made with reference to the views and orientations shown in the exemplary figures. A central axis is shown in the figures and described below. Terms such as "outer" and "inner" are relative to the central axis. For example, an "outer" surface means that the surfaces faces away from the central axis, or is outboard of another "inner" surface. Terms such as "radial," "diameter," "circumference," etc. also are relative to the central axis. The terms "front," "rear," "upper" and "lower" designate directions in the drawings to which reference is made.

Unless otherwise indicated, for the delivery system the terms "distal" and "proximal" are used in the following description with respect to a position or direction relative to a treating clinician. "Distal" and "distally" are positions distant from or in a direction away from the clinician, and "proximal" and "proximally" are positions near or in a direction toward the clinician. For the stent-graft prosthesis, "proximal" is the portion nearer the heart by way of blood flow path while "distal" is the portion of the stent-graft further from the heart by way of blood flow path.

Although the description is in the context of treatment of blood vessels such as the aorta, coronary, carotid and renal arteries, the invention may also be used in any other body passageways where it is deemed useful.

<FIG> illustrates a schematic of a blood vessel, in this case the aorta <NUM>, with a branched stent graft <NUM> deployed therein. The branched stent graft <NUM> can be used for treatment of an aneurysm <NUM> of the aorta <NUM>. The aorta <NUM> is shown with several branches, namely the brachiocephalic artery <NUM>, the left common carotid artery <NUM>, and the left subclavian artery <NUM>. The branched stent graft <NUM> is "branched" in that it includes a branch extending into or toward one of the branches of the aorta <NUM>. This branch of the stent graft can be referred to as a mobile external coupling, or more generally as a coupling <NUM>. In this embodiment, the coupling <NUM> is positioned such that when the branched stent graft <NUM> is deployed, the coupling <NUM> is aligned with and extends into the left subclavian artery <NUM>. Of course, in other embodiments the coupling <NUM> can be located on the branched stent graft <NUM> to align with and extend into the other branches of the aorta <NUM>, such as the brachiocephalic artery <NUM> or the left common carotid artery <NUM>. The placement of the coupling <NUM> in <FIG> is merely exemplary.

A primary guidewire <NUM> may first be inserted into the aorta <NUM>. A secondary guidewire <NUM> may be inserted into the aorta <NUM>, and into the desired branch where the coupling <NUM> is to be located, in this case the left subclavian artery <NUM>. The primary guidewire <NUM> may be utilized for tracking the stent graft <NUM> along to the appropriate deployment site, and the secondary guidewire <NUM> may be utilized for tracking of a secondary stent graft (not shown) for deployment within the left subclavian artery <NUM>. The stent grafts may be delivered using a stent graft delivery system, one embodiment of which is shown in <FIG> and described below.

During a surgical procedure, the stent graft delivery system may be utilized to track along both guidewires <NUM>, <NUM>, in which the delivery system includes lumens that each track along a respective one of the guidewires <NUM>, <NUM>. Deployment of the stent graft <NUM> may occur once situated in the proper location within the aorta <NUM>. During deployment, the coupling <NUM> expands radially outwardly with the secondary guidewire extending through the coupling <NUM>. Thereafter, the secondary stent graft (not shown) can track along the secondary guidewire <NUM>, through the coupling <NUM>, and, for example into the left subclavian artery <NUM>.

<FIG> illustrates an example of such a branched stent graft delivery system <NUM> for delivering and deploying the branched stent graft <NUM> to the aorta <NUM>. The delivery system <NUM> extends between a first end (e.g., proximal end) <NUM> and a second end (e.g., distal end) <NUM>. A threaded screw gear <NUM> may extend along an axis between the first end <NUM> and the second end <NUM>. A handle assembly <NUM> is preferably provided for grip by the clinician. The handle assembly <NUM> may include two separable portions, namely a front grip <NUM> and an external slider <NUM>. The front grip <NUM> may be fixed relative to the screw gear <NUM>, and the external slider <NUM> may rotate about a threaded outer surface of the screw gear <NUM> to move linearly along the screw gear <NUM>. For example, during deployment of a stent graft (such as the branched stent graft <NUM>), the external slider <NUM> is rotated to move toward the first end <NUM>. The external slider <NUM> is operatively coupled to a stent graft cover (e.g., a sheath or lumen) surrounding the stent graft <NUM>. This allows the sheath or lumen to be retracted with the linear movement of the external slider <NUM>, thus allowing the stent graft <NUM> to radially expand within the aorta <NUM>.

In a branched stent graft, such as the stent graft <NUM> of <FIG>, the coupling should be flexible so that, during deployment of the stent graft, the coupling can easily move and shift into proper alignment with the desired artery. For example, the coupling can be flexible enough such that it can accommodate a relatively high degree (e.g., <NUM> degrees) of off-positioning of the stent graft in either the proximal, distal, anterior, or posterior directions. This flexibility is beneficial, as the terrain of the aorta <NUM> and its branched vessels can be tumultuous, and can vary amongst different patients. Such flexibility can also make the placement of the secondary stent graft a priority without compromising the position of the coupling or the location of the coupling along the stent graft.

Therefore, according to various embodiments described herein, a branched stent graft is provided with structure surrounding the coupling that is designed to improve the flexibility of the coupling without sacrificing its structural makeup.

<FIG> illustrate various views of a branched stent graft <NUM>, according to an embodiment. The stent graft <NUM> is shown in a radially-expanded configuration, not installed into a blood vessel of a patient. In other words, the stent graft <NUM> is shown in these Figures in a preinstalled configuration in which the stent graft <NUM> is not yet compacted or compressed to fit within a catheter for insertion into a body of a patient.

<FIG> illustrate a branched stent graft <NUM>, according to one embodiment. The branched stent graft, also referred to as a main stent graft or simply a stent graft, can be configured for treatment of the aorta <NUM> and its branched arteries, as described above. The branched stent graft <NUM> can also be delivered and deployed using a stent graft delivery system, such as the delivery system <NUM> of <FIG>.

The branched stent graft <NUM> can be self-expanding, in that it includes structures that are shaped or formed form a material that can be provided with a mechanical memory to return the structure from a compressed or constricted delivery configuration to an expanded deployed configuration. In this embodiment, the stent graft includes a tubular graft <NUM> (also referred to as a body), and one or more stents <NUM> for supporting and expanding the graft <NUM>.

The graft <NUM> may be formed from any blood-impermeable material graft material, for example a low-porosity woven or knit polyester, DACRON material, expanded polytetrafluoroethylene, polyurethane, silicone, or the like. In another embodiment, the graft material is a natural material such as pericardium or another membranous tissue such as intestinal submucosa.

The stents <NUM> are radially-compressible and expandable, and are coupled (e.g., via stitching or suturing, laminated between layers of fabric, etc.) to the material of the graft <NUM> for supporting the graft <NUM>. The stents <NUM> are operable to self-expand into apposition with the interior wall of the aorta <NUM>. Each stent <NUM> may be constructed from a self-expanding or spring material, such as but not limited to nickel-titanium alloy (Nitinol), stainless steel, a pseudo-elastic metal such as a nickel titanium alloy or nitinol, various polymers, or a so-called super alloy, which may have a base metal of nickel, cobalt, chromium, or other metal, or other suitable material. The stents <NUM> may be fixed in a sinusoidal (or zig zag) patterned ring about the circumference of the graft <NUM>.

The stent graft <NUM> includes a proximal end <NUM>, a distal end <NUM>, and a main body <NUM> therebetween. The proximal end <NUM> may be provided with a proximal stent <NUM>, also referred to as a bare stent, anchor stent, or crown stent. The proximal stent <NUM> may extend outside of the graft material <NUM> such that it is configured to anchor to the inner walls of the vessel (e.g., aorta) <NUM>. In this embodiment, a majority of the proximal stent <NUM> may extend proximally beyond the graft material <NUM> such that a majority of the proximal stent <NUM> is not directly connected to the graft material <NUM>. Likewise, the distal end <NUM> may be provided with a distal stent <NUM>. In the illustrated embodiment, the distal stent <NUM> does not extend distally beyond the graft material <NUM>; however, in other embodiments, the distal stent <NUM> can be at least partially exposed, extending distally beyond the graft material <NUM> at the distal end <NUM> such that it too can be configured to anchor to the vessel.

The stent graft <NUM> also includes a mobile external coupling <NUM> (or, coupling) which can be designed and constructed similar to the coupling <NUM> described above. The coupling <NUM> is disposed on an outer surface of the stent graft <NUM> at a location corresponding to an opening in the graft material. The mobile external coupling <NUM> may be generally frustoconical-shaped, or volcano-shaped with sloped side walls <NUM> leading to an open top or opening <NUM>. The mobile external coupling <NUM> may be made of graft material that corresponds or matches to the graft material <NUM> of the body <NUM>, although the graft material of the coupling <NUM> can be a separate piece of graft material (e.g., different material composition, thickness, etc.) attached to the graft material <NUM>. A circumferential stent or annular stent <NUM> may be coupled to the graft material of the coupling <NUM> around the open top <NUM> of the mobile external coupling <NUM>. Also, the stent <NUM> may be formed of similar material as the other stents <NUM> of the stent graft <NUM>. As shown, the stent <NUM> may have a zig-zag or sinusoidal configuration around the top <NUM> of the mobile external coupling <NUM>. Additional description of the mobile external coupling <NUM> may be found in <CIT>.

<CIT> also includes examples of dual guidewire delivery systems. Aspects of the devices, delivery systems, and/or deployment methods of <CIT> may be combined with those of the present disclosure.

<FIG> are enlarged views of <FIG>, focusing on the region near the proximal end <NUM> and mobile external coupling <NUM>. The proximal stent <NUM> has peaks <NUM> that are bare, extending beyond the proximal end of the graft material <NUM>. In this embodiment, the proximal stent <NUM> has seven peaks <NUM>, and they extend generally uniform about the central longitudinal axis of the stent graft <NUM>. Thus, in <FIG>, some peaks <NUM> to the rear of the stent graft <NUM> are overlapped by the peaks <NUM> to the front of the stent graft <NUM> when looking from the orientation shown in <FIG>. With an odd number of peaks <NUM> and the spacing of the peaks <NUM> being generally uniform, the proximal stent <NUM> aligns or overlaps itself when looking from a certain angular orientation about the central axis, such as the view shown in <FIG>.

The proximal stent <NUM> can be stitched, sutured, or otherwise attached to the inside surface of the graft material <NUM>, as is shown in <FIG>. While the proximal stent <NUM> is shown attached to the inside of the graft material <NUM> in this embodiment, it may alternatively be attached to the outside of the graft material.

The stent graft <NUM> may also include a support stent <NUM>. The support stent <NUM> is directly adjacent the proximal stent <NUM> with no intervening stents therebetween. The support stent <NUM> is configured to provide additional support for the stent graft <NUM> in the region between the mobile external coupling <NUM> and the proximal end <NUM>. As the coupling <NUM> bends and flexes during placement within the treated vessel, the support stent <NUM> allows the coupling <NUM> to maintain flexibility without sacrificing the structural integrity of the main body <NUM> of the stent graft <NUM>. In other words, the support stent <NUM> can facilitate the relative flexing of the coupling <NUM> relative to the main body <NUM>. The support stent <NUM> may also improve the seal of the proximal end <NUM> with the vessel wall.

This function of the support stent <NUM> can be provided in multiple ways. In one or more embodiment, the support stent <NUM> is thinner than the proximal stent <NUM> and/or the other remaining stents of the stent graft <NUM>. For example, while the thickness of the stents <NUM>, <NUM> may be <NUM> millimeters (mm) thin, the support stent <NUM> may be <NUM> thin. This can provide the proper balance of allowing flexibility while maintaining structural integrity. Furthermore, in one or more embodiments, the support stent <NUM> has various peaks <NUM> that extend beyond the proximal end of the graft material <NUM>. These peaks <NUM> are exposed, similar to the peaks <NUM> of the proximal stent <NUM>. However, unlike the proximal stent <NUM>, a majority (e.g., <NUM> percent) of the support stent <NUM> is directly attached to or overlaps with the graft material <NUM> (i.e., a majority of the support stent <NUM> does not extend proximally beyond the graft material <NUM>). This allows the peaks <NUM> to allow the stents to make additional contact (e.g., two points of contact) with the treated vessel; both the proximal stent <NUM> and the support stent <NUM> are configured to contact the treated vessel upon deployment of the stent graft <NUM>, in locations where the graft material <NUM> is not present. Also, a minority (greater than zero, such as within a range of <NUM> to <NUM> percent) of the support stent <NUM> is located proximal of the proximal end (e.g., not directly attached to or overlapping with the graft material <NUM>).

Moreover, the peaks <NUM> can be circumferentially aligned with the peaks <NUM>, such that each peak <NUM> is circumferentially aligned with a corresponding one of the peaks <NUM>, as shown in <FIG>. In other words, the support stent <NUM> can be referred to as being aligned "in phase," with the proximal stent <NUM>, such that the peaks and valleys of the stents <NUM>, <NUM> follow the same general circumferential pattern. The support stent <NUM> may have the same number of peaks as the proximal stent (e.g., seven in the embodiment shown). While the proximal stent <NUM> is attached to the inside surface of the graft material <NUM>, the support stent <NUM> may be attached (e.g., stitched, sutured, etc.) to the outside surface of the graft material <NUM>. However, in other embodiments, the proximal and supports stents may be attached on the opposite surfaces or on the same surface (inner or outer).

The support stent <NUM> (and therefore the proximal stent <NUM>) may be circumferentially oriented such that one of the peaks <NUM> is circumferentially aligned with the opening <NUM> of the coupling <NUM> (e.g., the center of the opening). This provides additional room for a bracketing stent <NUM> (described below) to be disposed axially between the coupling <NUM> and the proximal end <NUM>/support stent <NUM>. Also, by aligning the peak <NUM> with the opening <NUM>, this allows maximum flex and deflection of the coupling <NUM> in the axial direction of the main body <NUM> without interference from the support stent <NUM>.

The stent graft <NUM> also includes a pair of bracketing stents, namely a first bracketing stent <NUM> and a second bracketing stent <NUM>. The first and second bracketing stents <NUM>, <NUM> may be each axially adjacent to the coupling <NUM>, in that no other stents are provided between the stents <NUM>, <NUM> and the coupling <NUM>. The first bracketing stent <NUM> is located proximally adjacent the coupling <NUM>, and the second bracketing stent <NUM> is located distally adjacent the coupling <NUM>. The first bracketing stent <NUM> may provide a "hi-lo" design, with the first bracketing stent <NUM> having a peak <NUM> circumferentially aligned with a center of the opening <NUM>, and "higher" than another peak <NUM> of the stent <NUM>. This "hi-lo" design can also apply for the second bracketing stent <NUM>.

In one or more embodiments, the first bracketing stent <NUM> is circumferentially in phase with the proximal stent <NUM> and/or the support stent <NUM>; peaks <NUM> of the first bracketing stent <NUM> may be circumferentially aligned with peaks <NUM> of the support stent <NUM>, and/or peaks <NUM> of the proximal stent <NUM>. The first bracketing stent <NUM> may have the same number of peaks as the support stent <NUM> and proximal stent <NUM>. Thus, one of the peaks <NUM> (i.e., peak <NUM>) is circumferentially aligned with a center of the opening <NUM> of the coupling <NUM>, thus providing the coupling with flexibility without sacrificing structural integrity of the main body of the stent graft <NUM>. This also provides an open area <NUM> of graft material <NUM> without a stent immediately proximally adjacent the coupling <NUM>, which provides additional flexibility for alignment of the coupling <NUM> within the treated vessel. If there is misalignment of the coupling <NUM> during installation, there will not be a stent pushing on the proximal side of the coupling <NUM> that could otherwise cause an unwanted bending of the coupling <NUM> during realignment of the stent graft <NUM>.

In one or more embodiments, the second bracketing stent <NUM> has a different number of peaks (e.g., one less peak) than the first bracketing stent <NUM>, support stent <NUM>, and proximal stent <NUM>. In one embodiment, stents <NUM>, <NUM>, and <NUM> have seven peaks and the second bracketing stent <NUM> has six peaks. Thus, the second bracketing stent <NUM> is preferably not in phase with the first bracketing stent <NUM>, support stent <NUM>, or proximal stent <NUM> all the way circumferentially about the stent graft <NUM>. In the illustrated embodiment, the second bracketing stent has a valley <NUM> (e.g., a part of the stent that is located most distally) that is in phase and in circumferential alignment with corresponding valleys of the first bracketing stent <NUM>, support stent <NUM>, and proximal stent <NUM>. This valley <NUM> is located on an opposite side of the stent graft <NUM> from the coupling <NUM> (e.g., the side configured to contact an inner curve of the aortic arch). Moreover, as shown in <FIG>, the second bracketing stent <NUM> becomes <NUM>-degrees out of phase with those stents <NUM>, <NUM>, <NUM> at a location circumferentially aligned with the opening <NUM> of the coupling <NUM>. In other words, the second bracketing stent <NUM> has a valley <NUM> that is circumferentially aligned with the peaks <NUM>, <NUM>, <NUM> and the opening <NUM>. The valley <NUM> is circumferentially opposite from the valley <NUM>. This provides an open area <NUM> of graft material <NUM> without a stent immediately distally adjacent the coupling <NUM>, which provides similar function and benefits as the opening <NUM>.

<FIG> are similar views of the stent graft <NUM> as <FIG>, now with focus on various axes. In particular, a first axis <NUM>, a second axis <NUM>, a third axis <NUM>, and a fourth axis <NUM> are provided to illustrate various relationships that will be described.

The first axis <NUM> intersects the peaks <NUM>, <NUM> of the support stent <NUM>. In at least one embodiment, all of the peaks <NUM>, <NUM> of the support stent <NUM> are circumferentially aligned about the stent graft <NUM> at a location proximally beyond the edge of the graft material <NUM>. In other words, the axis <NUM> is perpendicular to a longitudinal axis <NUM>. As described previously, a majority of the support stent <NUM> may be distal to the proximal edge of the graft material. In one embodiment, at least <NUM>% of the axial length of the support stent <NUM> may be distal to the proximal edge of the graft material. In other embodiments, at least <NUM>, <NUM>, or <NUM>% of the axial length of the support stent <NUM> may be distal to the proximal edge of the graft material. The peak of the support stent <NUM> may be completely proximal to the proximal edge of the graft material, such that there are two discrete contact points between the support stent <NUM> and the proximal edge of the graft material for each peak (e.g., one for each strut extending from the peak). Compared to a stent having a peak at the proximal edge of the graft material, which would have a single contact point, having the support stent <NUM> extend beyond the proximal edge of the graft material provides double the contact points and may improve the seal of the stent graft.

The second axis <NUM> intersects the peaks <NUM> of the first bracketing stent <NUM>. The second axis <NUM> may include two sections <NUM>', <NUM>" having different slopes relative to the longitudinal axis <NUM>. In at least one embodiment, the peaks <NUM> intersecting section <NUM>' become closer to the proximal end <NUM> of the stent graft <NUM> as the peaks <NUM> become circumferentially closer to the coupling <NUM>, with the peak <NUM> aligned with the coupling opening being the closest to the proximal end <NUM> of the stent graft <NUM>. Section <NUM>' may have a constant slope relative to the longitudinal axis <NUM>, as shown in <FIG>, or it may be non-constant but the intersected peaks <NUM> still continuously move closer to the proximal end as they become circumferentially closer to the coupling <NUM>. Section <NUM>" of second axis <NUM> may have a slope relative to longitudinal axis <NUM> that is less than section <NUM>' (i.e., closer to perpendicular). In one embodiment, section <NUM>" is perpendicular to longitudinal axis <NUM>. The two sections may intersect at a peak <NUM> on either side of the coupling <NUM>, such that two peaks of the support stent intersect with both sections <NUM>' and <NUM>". In one embodiment, all peaks <NUM> of the support stent intersect at least one of section <NUM>' or <NUM>" of the second axis <NUM>. In the embodiment shown, section <NUM>' intersects five peaks <NUM> - the peak <NUM> aligned with the opening of the coupling <NUM> and two directly adjacent stent peaks on either circumferential side thereof. Section <NUM>" intersects four peaks - the four peaks most circumferentially opposite the opening of the coupling <NUM>. Accordingly, two peaks intersect both sections and are at a transition between the sloped section <NUM>" and the perpendicular (in this embodiment) section <NUM>". The dual sections of second axis <NUM> provide several benefits, such as providing the open area <NUM> of graft material <NUM> which provides additional flexibility for alignment of the coupling <NUM> within the treated vessel, as described above. This also allows for the first bracketing stent <NUM> to have proper spacing and support of the coupling <NUM> while maintaining proper alignment with the other stents at the side of the stent graft <NUM> opposite the coupling <NUM> (e.g., the left hand side of the view in <FIG>). While not shown with a separate axis, the valleys of first bracketing stent <NUM> that are adjacent to the peaks that intersect section <NUM>" may also be aligned along a perpendicular axis parallel to section <NUM>".

The third axis <NUM> intersects the peaks of the second bracketing stent <NUM>. In at least one embodiment, the peaks of the second bracketing stent <NUM> become further away from the proximal end <NUM> of the stent graft <NUM> as the peaks becomes circumferentially closer to the coupling <NUM>. In other words, the third axis <NUM> is oblique relative to longitudinal axis <NUM>, and is not parallel to the first axis <NUM> or fourth axis <NUM>. In the illustrated embodiment, the third axis <NUM> is linear, but in other embodiments the third axis <NUM> is non-linear similar to the second axis <NUM>. The slope of the third axis <NUM> relative to the longitudinal axis <NUM> allows for proper spacing and support of the coupling <NUM> while maintaining proper alignment with the other stents at the side of the stent graft <NUM> opposite the coupling <NUM> (e.g., the left hand side of the view in <FIG>). Moreover, the third axis <NUM> does not intersect the opening <NUM>, such that the peaks of the second bracketing stent <NUM> on the side of the main body where the coupling <NUM> is located (e.g., directly on either side of <NUM>), are positioned distally of the opening <NUM>. For example, referring to <FIG>, the third axis <NUM> never crosses over the opening <NUM> on the illustrated view of the stent graft <NUM> nor do those peaks axially overlap with the opening <NUM>. The same may be true for the valleys of the first bracketing stent <NUM> on either side of the coupling <NUM> - they may not intersect or overlap axially with the opening <NUM>.

As can be seen in the illustrated embodiment in <FIG>, the second axis <NUM> allows for the "hi-lo" design described above. Also, the bracketing stents <NUM>, <NUM> diverge about the coupling <NUM>, but converge on the side of the stent graft <NUM> opposite the coupling <NUM>. The spacing of the stents on the side of the stent graft <NUM> opposite the coupling <NUM> can be generally uniform, while the spacing of the stents on the side of the stent graft <NUM> with the coupling <NUM> can be nonuniform to make room for the coupling <NUM>.

The fourth axis <NUM> intersects the valleys <NUM> of the second bracketing stent <NUM>. In the illustrated embodiment, the fourth axis <NUM> is perpendicular to the longitudinal axis <NUM>, and parallel to the first axis <NUM>. However, in another embodiment, the fourth axis <NUM> is oblique relative to the longitudinal axis <NUM>, and can be parallel to the third axis <NUM> or otherwise oblique. In the illustrated embodiment of <FIG>, the third axis <NUM> and fourth axis <NUM> create a wedge (e.g., in side-view shown in <FIG>), in that the fourth axis <NUM> is perpendicular to the longitudinal axis <NUM> while the third axis <NUM> is oblique to the longitudinal axis <NUM>. This creates a "wedge" design, in which the valley-to-valley line is perpendicular to the longitudinal axis <NUM> but the peak-to-peak line gets higher (e.g., more proximal) toward the back of the stent graft <NUM> (e.g., the left-hand side of <FIG>). The amplitude or distance between the peaks and valleys increases in the direction toward the back of the stent graft <NUM>. This can provide an open area <NUM> on either circumferential side of the coupling <NUM>. The open area <NUM> can be an absence of stents, allowing the coupling <NUM> to move sideways (e.g., circumferentially relative to the axis <NUM>) without interference from the bracketing stents <NUM>, <NUM>. This provides additional capabilities for mobility of the coupling <NUM>.

While embodiments are described herein with respect to a branched stent graft, aspects of these embodiments may also be used in non-branched stent grafts (e.g., cylindrical or tubular stent grafts). For example, any of the proximal stent, support stent, first bracketing stent, and/or second bracketing stent may be incorporated into a non-branched stent graft in a similar manner as described herein.

Claim 1:
A stent graft (<NUM>) comprising:
a main body (<NUM>) extending along a longitudinal axis (<NUM>) when in a preinstalled configuration prior to insertion into a body of a patient, the main body extending between a proximal end (<NUM>) and a distal end (<NUM>) thereof; and
a mobile external coupling (<NUM>) extending away from the main body and configured to align with a secondary blood vessel within the body to provide access thereto;
wherein the main body includes a plurality of stents (<NUM>) extending thereabout, the plurality of stents including a first bracketing stent (<NUM>) extending about a proximal side of the mobile external coupling, and a second bracketing stent (<NUM>) located adjacent the first bracketing stent and extending about a distal side of the mobile external coupling;
wherein the first bracketing stent (<NUM>) includes a first plurality of peaks (<NUM>, <NUM>, <NUM>) that are aligned along a first axis (<NUM>), and the second bracketing stent (<NUM>) includes a second plurality of peaks that are aligned along a second axis (<NUM>), wherein the first and second axes diverge from one another in a circumferential direction toward the mobile external coupling.