Patent Description:
Prostheses are implanted in blood vessels and other organs of living bodies. For example, prosthetic endovascular grafts constructed of biocompatible materials have been employed to replace or bypass damaged or occluded natural blood vessels. In general, endovascular grafts include a graft anchoring component that operates to hold a tubular graft component of a suitable graft material in its intended position within the blood vessel. The graft anchoring component typically includes one or more radially-compressible stents that are radially expanded in situ to anchor the tubular graft component to the wall of a blood vessel or anatomical conduit.

Rather than performing a traumatic and invasive open surgical procedure to implant a graft, endovascular grafts (e.g., stent grafts) may be deployed through a less invasive intraluminal delivery procedure. A lumen or vasculature may be accessed at a convenient and less traumatic entry point of the patient's body, and the stent graft may be routed through the vasculature to the site where the prosthesis is to be deployed. Intraluminal deployment typically uses a delivery catheter with tubes or shafts arranged for relative axial movement. For example, an expandable stent graft may be compressed and disposed within a distal end of an outer shaft of the delivery catheter fixed to an inner shaft. The delivery catheter may then be maneuvered, typically tracked through a body lumen until a distal end of the delivery catheter and the stent graft are positioned at the intended treatment site. The stent graft can then be deployed and radially expanded within the blood vessel. <CIT> describes a side branch stent graft.

The invention concerns a stent graft as defined by claim <NUM>. According to one embodiment, a stent graft is expandable from a radially-collapsed configuration to a radially-expanded position. The stent graft includes a main body extending along a main longitudinal axis and having a proximal end and a distal end. The stent graft also includes a first leg extending from the distal end of the main body, a second leg extending from the distal end of the main body, and a plurality of stitches coupling the main body to the first leg. The plurality of stitches forms a stitch path that extends in a direction oblique to the main longitudinal axis of the main body when the stent graft is in a preinstalled configuration prior to insertion into a body of a patient.

According to another embodiment, a stent graft includes a main body extending along a main longitudinal axis and having a proximal end and a distal end. The stent graft also includes a first leg attached to the distal end of the main body along a first seam that extends along a first seam path. The stent graft also includes a second leg attached to the distal end of the main body along a second seam that is continuous with the first seam and extends along a second seam path. The first seam path is oblique relative to the second seam path when the stent graft is in a preinstalled configuration prior to insertion into a body of a patient.

According to yet another embodiment, a stent graft includes a main body extending along a longitudinal axis when the stent graft is in a preinstalled configuration prior to insertion into a body of a patient. The stent graft includes a first leg extending axially from the axial end in a direction parallel to the longitudinal axis. The stent graft also includes a second leg extending axially from the axial end in a direction parallel to the longitudinal axis, the second leg being narrower than the first leg. The stent graft also includes a plurality of stitches coupling the main body to the first leg, the plurality of stitches forming a stitch path that extends in a direction oblique to the longitudinal axis.

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.

As used herein, the proximal end of a prosthesis such as bifurcated stent graft is the end closest to the heart via the path of blood flow, whereas the distal end is the end furthest away (e.g., downstream of blood flow) from the heart during deployment. In contrast, the distal end of the catheter is usually identified to the end that is farthest from the operator (handle) while the proximal end of the catheter is the end nearest the operator (handle). However, those of skill in the art will understand that depending upon the access location, the stent graft and delivery system description may be consistent or opposite in actual usage.

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

Endovascular stent grafting, or endovascular aneurysm repair (EVAR), is a form of treatment for abdominal or thoracic aortic aneurysm that is less invasive than open surgery. Endovascular stent grafting uses an endovascular stent graft to reinforce the wall of the aorta and to help keep the damaged area from rupturing by excluding the aneurysm from blood flow. Stent grafts are generally tubular open-ended structures providing support for damaged, collapsing, or occluded blood vessels, such as the aorta. Stent grafts are flexible, which allows them to be inserted through, and conform to, tortuous pathways in the blood vessels. For example, stent grafts may be radially expandable from a radially-compressed (or radially-constricted) configuration for delivery to the affected vessel site to a radially-expanded configuration when deployed at the affected vessel treatment site, with the radially-expanded configuration having a larger diameter than the radially-compressed configuration. Stent grafts may be inserted in the radially compressed configuration and expanded to the radially-expanded configuration either through a self-expanding mechanism, or through the use of a balloon catheter, for example.

In one example, an EVAR procedure may include inserting a guide wire into a portion of the patient's body, such as the femoral artery. Once the guidewire is inserted into the artery, it may be gently pushed toward the site of the aneurism. A stent graft delivery system, which may include a catheter and stent graft, may be placed over the guidewire and inserted along the guidewire into the site of the aneurism. The stent graft may be guided within the catheter in its radially-compressed configuration and to the site of the aneurism. There may be radiopaque markers at a distal end of the stent graft delivery system or on the stent graft itself to allow the surgeon to guide the stent graft into the proper position. Once in proper position, the stent graft can be expanded from the radially-compressed configuration to the radially-expanded configuration. This can be done, for example, by pulling back a stent-graft cover, allowing the stent graft to expand due to its fabric being biased outwards. Once deployed into the radially-expanded configuration, the stent graft can be held in place with metallic hooks or stents. The catheter can then be removed, while the stent graft remains.

In some applications, the blood vessel wall or anatomical conduit in which the stent-graft is to be implanted is highly curved or angled. Moreover, packaging volume within the catheter may be limited.

<FIG> shows an example of a stent graft <NUM> in its installed, radially-expanded configuration within a blood vessel <NUM>, in this case a patient's aorta, more particularly the abdominal aorta. Once affixed within the blood vessel <NUM>, the stent graft <NUM> provides a tube or pipe for blood flow, guiding the blood flow through the stent graft <NUM>. If the stent graft <NUM> is located within an aneurysm <NUM> of the blood vessel <NUM>, the blood flow through the stent graft <NUM> may reduce the pressure within the aneurysm and allow it to reduce in size (regress) or remain stable. In one embodiment, graft material of the stent graft <NUM> is non-permeable, e.g., is polyester terephthalate (PET), expanded polyester terephthalate (ePET), polytetrafluoroethylene (PTFE), or other non-permeable graft material. As graft material is non-permeable, blood or other fluid is prevented from passing through graft material.

As shown in <FIG>, the stent graft <NUM> may include main body <NUM>, a first leg <NUM> extending from the main body <NUM>, and a second leg <NUM> extending from the main body <NUM>. The first leg <NUM> may be ipsilateral to where the initial guidewire was installed, and the second leg <NUM> that may be contralateral to the first leg <NUM>, and may be shorter than the first leg <NUM>. The first leg <NUM> may extend into a first iliac artery <NUM>, while the second leg <NUM> may extend into a second iliac artery <NUM>. The first and second legs <NUM>, <NUM> may also guide blood flow therethrough, allowing those portions of the iliac arteries to heal, and removing stress from those regions of the arteries. A second stent graft may subsequently be inserted within and attached to either or both of the first and second legs <NUM>, <NUM> to elongate the overall profile of the stent graft.

The first leg <NUM> may be connected to the main body <NUM> by stitching or a seam. Likewise, the second leg <NUM> may be connected to the main body <NUM> by stitching or a seam. When the stent graft <NUM> is in the radially-contracted configuration (e.g., during delivery into the patient's body), the seam at the interface between the main body <NUM> and the legs <NUM>, <NUM> can bunch up. <FIG> illustrate this concept. In <FIG>, the stent graft <NUM> is shown being inserted into a blood vessel <NUM> with any outer catheter removed for illustrative purposes. The stent graft <NUM> is in its radially-contracted configuration and is guided through the blood vessel <NUM> via a guide <NUM>. A plurality of stitches <NUM> (e.g., stitches that connect the main body <NUM> to one or both of the legs <NUM>, <NUM>) can form a seam that can create a bulge or bump <NUM> on the outer portion of the stent graft <NUM> during installation. This is due to the material of the stitches <NUM> being in close relative axial proximity. This may have a potential to reduce available space within the catheter during delivery, for example. While the bunch or bulge <NUM> of stitching material is gone when the stent graft <NUM> is in its radially-expanded configuration (as shown in <FIG>), the bunch or bulge <NUM> is nonetheless present during the insertion phase when the stent graft <NUM> is in its radially-contracted configuration (as shown in <FIG>).

Therefore, according to various embodiments described herein, a stent graft is provided with stitches or sutures that define an oblique stitch path. As used herein, the term "oblique" is intended to mean slanted, or angled by an angle other than a right angle or parallel angle. And, as used herein, the term "stitch path" or "seam path" is intended to mean an average or nominal direction of a group of stitches that form at least a seam. Of course, within each seam, a plurality of individual or localized stitches (e.g., a small group of stitches) may be oriented in different directions, but the "stitch path" in this disclosure is intended to mean an overall direction of a collective group of stitches; in other words, a nominal direction of the stitches. In one embodiment, a group of <NUM> to <NUM> stitches can collectively define a seam path, such that the seam path extends along a path that reflects the nominal direction of these <NUM> to <NUM> stitches.

A stent graft with an oblique seam path is generally shown in <FIG>, in which the stent graft has a seam <NUM> connecting the main body <NUM> to the legs <NUM>, <NUM>, wherein the seam <NUM> is oblique relative to the length of the stent graft, as will be described further below. While only two legs <NUM>, <NUM> are shown in this Figure and <FIG>, more than two legs may be provided. For example, three, four, or five legs may extend from the main body <NUM>, and may be attached thereto via a seam. The stitching that joins the main body to at least one of the legs can be angled relative to a longitudinal axis of the main body and/or leg. This allows the stitching of the seam to be more dispersed along the length of the stent graft when the stent graft is in its radially-contracted configuration. This can remove or reduce the size of the bulge of the stitching explained above when in the radially-contracted configuration. By creating a seam that distributes the stitching or suture material along the length of the stent graft, packing of this material will occupy an effectively smaller cross-sectional area at a given axial location of the stent graft.

Referring to <FIG>, a stent graft <NUM> with such an oblique seam is shown according to one embodiment. The stent graft <NUM> may be used in abdominal aortic aneurysms (AAA), thoracoabdominal aortic aneurysms (TAAA), or any other aortic aneurysms where a splitting of blood flow into multiple lumens is desired. The stent graft <NUM> of <FIG> is shown in its radially-expanded configuration, not deployed inside a patient's body. The stent graft <NUM> has a main body <NUM> that extends from a proximal end <NUM> to a first leg <NUM> and a second leg <NUM> located at a distal end <NUM> of the main body <NUM>. A first seam <NUM> joins the first leg <NUM> to the main body <NUM>. A second seam <NUM> joins the second leg <NUM> to the main body <NUM>. The first and second seams <NUM>, <NUM> may be continuous, in that the stitching continues uninterruptedly in joining the first leg <NUM> to the main body <NUM>, and in joining the second leg <NUM> to the main body <NUM>. In one embodiment, the first leg <NUM> feeds into, or is connected to, a first tributary leg <NUM> and a second tributary leg <NUM> (which may also be called branch legs). Each of the tributary/branch legs <NUM>, <NUM> are optional additions to the stent graft <NUM> for extending (directly or via additional extensions) into respective blood vessels (e.g., the renal, celiac, and/or SMA arteries). The second leg <NUM> may be a bypass leg to allow flow into the distal aorta. Therefore, in certain embodiments, a proximal end of the first leg <NUM> may be connected to the main body <NUM> via a seam or stitching, and a distal end of the first leg <NUM> may be connected to a first tributary leg <NUM> and a second tributary leg <NUM>. A third seam <NUM> joins the first leg <NUM> to the first tributary leg <NUM>, and a fourth seam <NUM> joins the first leg <NUM> to the second tributary leg <NUM>. Each seam <NUM>, <NUM>, <NUM>, <NUM> can include fabric, polymer, or metal stitching, for example. While the embodiment shown has two tributary legs, in other embodiments there may be three or more tributary legs. In another embodiment, second leg <NUM> may also have two or more tributary legs attached thereto.

As can be seen in <FIG>, the main body <NUM> extends along a main longitudinal axis <NUM>. Each of the legs <NUM>, <NUM>, <NUM>, <NUM> extend along respective axes that are parallel to the main longitudinal axis <NUM> when the stent graft <NUM> is in the radially expanded configuration, not installed into various blood vessels in a patient. In other words, the stent graft <NUM> is shown in <FIG> 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.

Each seam includes a plurality of stitches that extend along a stitch path. For example, the first seam <NUM> includes a first plurality of stitches that extend along a first stitch path <NUM>, also referred to as a seam path or seam axis. Likewise, the second seam <NUM> includes a plurality of stitches that extend along a second stitch path <NUM>. At least one or both of the stitch path axes <NUM>, <NUM> can extend at an angle that is oblique relative to the longitudinal axis <NUM> and to a normal axis that is normal or perpendicular to the axis <NUM>. In the embodiment shown in <FIG>, only the first stitch path <NUM> is oblique relative to the longitudinal axis <NUM>. However, in other embodiments, the second stitch path <NUM> extends parallel or colinear with the first stitch path <NUM> and oblique relative to the longitudinal axis <NUM>. In still other embodiments, both the first and second stitch paths <NUM>, <NUM> may be oblique to the longitudinal axis <NUM>, but at different angles. In another embodiment, the second stitch path <NUM> may be oblique to the longitudinal axis <NUM>, while the first stitch path <NUM> is normal to it.

In one embodiment, the first stitch path <NUM> and the second stitch path <NUM> form an angle α<NUM> that is acute. In one embodiment, α<NUM> is between <NUM>-<NUM> degrees, and can in more particular embodiments be between <NUM>-<NUM> degrees. This would yield an acute angle between the first stitch path <NUM> and the longitudinal axis <NUM> of between <NUM>-<NUM> degrees, and between <NUM>-<NUM> degrees in the respective embodiments. These angles allow the stitching to be spread along the axial direction of the stent graft <NUM> to reduce or remove the prevalence of the bulge or bump of stitching material in the radially-compressed configuration without increasing the length of the seam to an undesirable amount that might reduce strength and increase material usage.

By providing at least one stitch path <NUM>, <NUM> that extends in an oblique direction relative to the longitudinal axis <NUM>, the stitching between the main body <NUM> and at least one of the legs <NUM>, <NUM> is spread out along the length of the stent graft <NUM>. Therefore, when the stent graft <NUM> is in its radially-compressed configuration, the stitches do not coalesce to such a degree that a bulge or bump on the exterior profile of the stent graft <NUM> would hinder packaging or movement of the stent graft <NUM> within a catheter (as described above with reference to <FIG>). As explained herein, in some embodiments only one stitch path <NUM> is oblique to the longitudinal axis. This stitch path is located at the joining of the main body <NUM> to the first leg <NUM>, which may be wider than the second leg <NUM>. By having an oblique stitch path at the joining between the main body at the larger of the two legs, the stitching can be spread out along a portion of the length of the stent graft where a large amount of stitching may otherwise bunch up due to the relatively large width of the first leg <NUM>.

Referring to <FIG>, one or more of the seams connecting the first leg <NUM> to the tributary legs <NUM>, <NUM> can be oblique to the longitudinal axis <NUM>. In particular, in an embodiment, the third seam <NUM> includes a third plurality of stitches that extend along a third stitch path <NUM>, and the fourth seam <NUM> includes a fourth plurality of stitches that extend along a fourth stitch path <NUM>. Like the first and second seam axes <NUM>, <NUM>, the third seam axis <NUM> can be angled relative to the third seam axis <NUM>. For example, the fourth seam axis <NUM> can extend in a direction normal to the longitudinal axis <NUM>, while the third seam axis <NUM> can extend in a direction oblique to the fourth seam axis <NUM>. In other embodiments, both axes <NUM>, <NUM> extend in an oblique direction to the longitudinal axis <NUM>. In still other embodiments, both the third and fourth seam axes <NUM>, <NUM> may be oblique to the longitudinal axis <NUM>, but at different angles. In another embodiment, the fourth seam axis <NUM> may be oblique to the longitudinal axis <NUM>, while the third seam axis <NUM> is normal to it. The third stitch path <NUM> and the fourth stitch path <NUM> can intersect at an angle α<NUM> that may be similar or equal to α<NUM>.

By providing at least one stitch path <NUM>, <NUM> that extends in an oblique direction to the longitudinal axis <NUM>, the stitching between the first leg <NUM> and at least one of the tributary legs <NUM>, <NUM> is spread out along the length of the stent graft <NUM>. Therefore, when the stent graft <NUM> is in its radially-compressed configuration, the stitches do not coalesce to such a degree that a bulge or bump on the exterior profile of the stent graft <NUM> would hinder packaging or movement of the stent graft <NUM> within a catheter.

<FIG> illustrates a plan view of fabric <NUM> that is cut to shape and stitched together to form the shape of the stent graft <NUM>. The fabric <NUM> can be non-permeable, such as polyester terephthalate (PET), expanded polyester terephthalate (ePET), polytetrafluoroethylene (PTFE), or other non-permeable graft material. The fabric may include a first fabric portion <NUM> that eventually forms the main body <NUM>, a second fabric portion <NUM> that eventually forms the first leg <NUM>, and a third fabric portion <NUM> that eventually forms the second leg <NUM>.

At the distal end of the fabric <NUM>, the first fabric portion <NUM> includes a first edge <NUM> and a second edge <NUM>. The second edge <NUM> extends generally perpendicular to a longitudinal edge <NUM> of the first fabric portion <NUM>. This allows the main body <NUM> to have a portion of its axial end to extend generally perpendicular to the longitudinal axis <NUM>. However, unlike the second edge <NUM>, the first edge <NUM> extends along a direction that is offset or angled (e.g., not perpendicular) to the second edge <NUM> and the longitudinal edge <NUM>. The second fabric portion <NUM> has a corresponding proximal edge <NUM> that is offset or angled to match the shape of the first edge <NUM>. Stitching <NUM> or the like can attach the proximal edge <NUM> of the second fabric portion <NUM> to the first edge <NUM> of the first fabric portion <NUM>. This forms the first leg <NUM> having an offset seam axis <NUM>. The third fabric portion <NUM> has proximal edge <NUM> that corresponds in shape to the second edge <NUM> of the first fabric portion <NUM>. Once again, stitching <NUM> or the like can attach the proximal edge <NUM> to the second edge <NUM>. This forms the second leg <NUM> having a seam axis <NUM> that is angled relative to the seam axis <NUM>.

Claim 1:
A stent graft (<NUM>, <NUM>) expandable from a radially-collapsed configuration to a radially-expanded position, the stent graft (<NUM>, <NUM>) comprising:
a main body (<NUM>, <NUM>) extending along a main longitudinal axis (<NUM>) and having a proximal end (<NUM>) and a distal end (<NUM>);
a first leg (<NUM>, <NUM>) extending from the distal end (<NUM>) of the main body (<NUM>, <NUM>);
a second leg (<NUM>, <NUM>) extending from the distal end (<NUM>) of the main body (<NUM>, <NUM>); and
a plurality of stitches coupling the main body (<NUM>, <NUM>) to the first leg (<NUM>, <NUM>), the plurality of stitches forming a stitch path (<NUM>) that extends in a direction oblique to the main longitudinal axis (<NUM>) of the main body (<NUM>, <NUM>) when the stent graft (<NUM>, <NUM>) is in a preinstalled configuration prior to insertion into a body of a patient; wherein each of the first and second legs (<NUM>, <NUM>, <NUM>, <NUM>) extend along respective axes that are parallel to the main longitudinal axis (<NUM>) when the stent graft (<NUM>, <NUM>) is in the preinstalled configuration prior to insertion into a body of a patient.