Stent, stent system, and methods of implanting stents

Abstract

A stent for crossing over the common iliac arteries comprises a first open end and a second open end, and the wall defines a central lumen of the stent between the first open end and the second open end. An aperture is formed in the wall at a location between the first end and the second end of the stent, and wherein in the radially expanded state the aperture has a contour which is suitable for aligning with an open end of another stent for branching off the central lumen of the stent through the open end of that other stent, so that a flow path between the central lumen and the branched-off lumen is free from obstructions. A catheter containing the stent is also disclosed. A method of implanting a stent in the common iliac arteries is also disclosed.

Description

[0001] Angiomed GmbH & Co .Medi zintechnik KG HE REF : 258593 t! 0 / v9

[0002] Stent, Stent System, and Methods of Implanting Stents

[0003] Field of the Invention

[0004] A stent for crossing over the common iliac arteries and a method of implanting a stent across the common iliac arteries are provided. A stent system comprising the stent and an aortic stent is also provided. A method of implanting a stent in the common iliac arteries is provided. A method of implanting the stent system is also provided.

[0005] Background

[0006] Aortoiliac occlusive disease occurs when deposits, such as calcium, build up in the aorta, or in and around the aortoiliac bifurcation, or in the common iliac arteries, proximate to the aortoiliac bifurcation. These deposits can impede blood flow and can lead to numerous symptoms including pain, numbness, or cramping in the lower limbs, and gangrene in the feet.

[0007] In cases where deposits have built up in the inferior end of the (descending) aorta, i.e., proximate to the aortoiliac bifurcation, a stent or “aortic stent” may be implanted in this region. The deposits typically partially occlude the aorta, leaving only a narrow passage for blood flow. The stent is inserted in a radially-compact state through this narrowed passage. The stent is then transitioned to a radially-expanded state in which the stent presses radially outward on the deposits and provides a wider path for blood flow through a central lumen of the stent.

[0008] Deposits can also build up in the aortoiliac bifurcation itself, possibly in addition to buildup of deposits in the aorta. One established treatment for this condition is to implant kissing stents in the aortoiliac bifurcation. In this procedure, a first stent is implanted that crosses from the aorta to one of the right and left common iliac arteries, and a second stent is then implanted that crosses from the aorta to the other of the right and left common iliac arteries. The superior ends of the two stents are generally positioned to be immediately adjacent one another or touching one another, with said ends located either within the inferior end of the aorta or within the aortoiliac bifurcation itself - the exact placement may be determined by clinical indications. In this arrangement, the stents are referred to in the art as “kissing stents”. Once implanted, one kissing stent provides a now-widened passage for blood from the aorta to the right common iliac artery, and the other kissing stent provides a now-widened passage for blood from the aorta to the left common iliac artery. In this way, proper blood flow through the aorta and into the common iliac arteries may be restored. Kissing stents may also help treat deposits that have built up in the common iliac arteries, proximate to the aortoiliac bifurcation. Angiomed GmbH & Co .Medi zintechnik KG HE REF : 258593 t! 0 / v9

[0009] It is desirable to reduce the number of accesses into a patient’s vasculature during surgery to treat aortoiliac occlusive disease, as each access is a further infection risk and a further location that needs to heal after surgery. Thus, there is need in the art for improved apparatuses and methods for treating aortoiliac occlusive disease.

[0010] Summary of the Invention

[0011] According to a first aspect, there is provided a stent for crossing over the common iliac arteries, the stent being transitionable between a radially compacted state and a radially expanded state; wherein the stent further comprises a first open end and a second open end, and wherein the wall defines a central lumen of the stent between the first open end and the second open end; wherein in at least the radially expanded state an aperture is formed in the wall at a location between the first end and the second end of the stent, and wherein in the radially expanded state the aperture has a contour which is suitable for aligning with an open end of another stent for branching off the central lumen of the stent through the open end of that other stent, so that a flow path between the central lumen and the branched-off lumen is free from obstructions.

[0012] Once implanted, the central lumen of the stent may provide an unobstructed channel for blood flow in at least the superior end of both common iliac arteries. Blood may therefore flow from the aorta and enter the stent via the aperture and then flow into the common iliac arteries.

[0013] The aperture may be shaped such that, when viewed along an axis that passes through a centerpoint of the aperture and a point on the stent diametrically opposite the centerpoint, the aperture has an oval shape or a circular shape. That is, while the edge of the aperture may describe a 3D shape (e.g. a saddle shape), the shape of the aperture when viewed “top down” is circular or oval. Put another way, when the stent is implanted, blood flowing from the aorta into the aperture “sees” a circular or oval shaped aperture. An oval shape in particular may match the shape of a native unobstructed aorta in this region. That is, the native unobstructed inferior end of the aorta and the aortoiliac bifurcation have an oval cross sectional shape in the patient’s transverse plane. The smooth outline of a circular or oval shape of the aperture may reduce turbulence in blood flowing into the stent from the aorta.

[0014] The circular shape may have a diameter of greater than 10 mm or greater than 20 mm. The oval shape may have a major axis and a minor axis, and a diameter along the major axis may be greater than 10 mm or greater than 20 mm. Angiomed GmbH & Co .Medi zintechnik KG HE REF : 258593 t! 0 / v9

[0015] The wall of the stent may be formed from one or more struts. These may provide structural strength to the stent and allow it to take on both the radially expanded state and the radially compacted state.

[0016] Optionally, the aperture is not crossed by any struts. Struts crossing the aperture may introduce turbulence or otherwise distort fluid flow of the blood entering the stent.

[0017] In the radially expanded state, the one or more struts may define a plurality of holes in the wall, each hole having a respective hole surface area; wherein the aperture has an aperture surface area; and wherein the aperture surface area is at least twice as large as a largest of the hole surface areas. In this way, the aperture may be clearly distinct from the holes between the struts, even in the case of an uncovered stent.

[0018] The aperture may have a smooth outer edge. In many known stents, the holes that exist between the struts, which are to allow the stent to expand radially, are square, diamond shaped, or have a zig-zag outer profile, all of which provide sharp corners around the edge of the hole. Such discontinuities may introduce turbulence in blood flowing through the hole. By providing the aperture with a smooth outer edge, without such discontinuities, such turbulence may be reduced or avoided.

[0019] The stent may be a covered stent having a cover, wherein a cover aperture is formed in the cover and the cover aperture overlaps the aperture. That is, the aperture may be defined by the stent excluding the cover, in which case the cover also has an aperture that overlaps (i.e. is in registration with) the aperture, such that the aperture of the stent remains unaffected by the presence of the cover. Alternatively, the cover aperture may itself be the aperture of the stent.

[0020] The stent may further comprise one or more radiopaque markers, wherein the radiopaque markers are for determining an orientation of the stent while the stent is in the radially compacted state. These radiopaque markers may allow a user, e.g. a physician, to view the stent under imaging while performing a procedure to implant the stent. The radiopaque markers allow the user to clearly identify the position and orientation of the stent while it is in the radially compacted state, such that the user can set the stent to the correct positioning and orientation before transitioning the stent to its radially expanded state. In particular, this allows the user to correctly orient the aperture so that, when the stent transitioned to its radially expanded state, the aperture is facing towards the patient’s aorta. Angiomed GmbH & Co .Medi zintechnik KG HE REF : 258593 t! 0 / v9

[0021] Two radiopaque markers may be positioned such that, in the radially expanded state, the two radiopaque markers are positioned on opposite sides of the aperture. In cases where the aperture is oval when the stent is in the radially expanded state, the two radiopaque markers may be positioned diametrically opposite one another along either a major axis of the oval or a minor axis of the oval. This position may allow the user to easily assess the position where the aperture will be once the stent is expanded.

[0022] The wall may comprise a chimney portion, wherein, when the stent is in the radially expanded state, the aperture is formed at an end of the chimney portion that is distalmost from a centreline of the stent that extends from the first open end to the second open end. This chimney portion may give the overall stent the shape of a truncated inverted-Y. This chimney portion may assist in pressing back deposits or lesions within the aortoiliac bifurcation. The chimney portion may also assist in positioning and orienting the stent, by bearing against walls of the aortoiliac bifurcation.

[0023] One or more radiopaque markers may be formed on the chimney portion. This may assist in orienting the stent by clearly identifying, to a user, under imaging, where the chimney portion is and orienting it so that it points towards the aorta.

[0024] The stent may be divided into sections, such as three sections, where the middle section is wider than either of the two end sections, and the middle section contains the aperture. The stent may comprise a first section, a second section, and a third section, wherein the first section extends from the first open end to a first transition region, wherein the third end extends from the second open end to a second transition region, and wherein the second region extends from the first transition region to the second transition region; wherein the second region includes the aperture; wherein every cross sectional area of the second section, taken in a plane transverse to a centerline joining the first open end to the second open end, is: larger than any cross sectional area of the first section, taken in a plane transverse to the centerline, and larger than any cross sectional area of the third section, taken in a plane transverse to a centerline.

[0025] This may allow the aperture to have a larger overall cross-sectional area, by being formed in the wider, second, section of the stent, while the first and third sections may be smaller so as to better fit within respective ones of the common iliac arteries. The first transition region may provide a smooth transition between an end of the (smaller) first section and the (larger) second section. The second transition region may provide a smooth transition between an end of the (smaller) third section and the (larger) second section. The transition regions may avoid generating undesirable turbulence in Angiomed GmbH & Co .Medi zintechnik KG HE REF : 258593 t! 0 / v9 the blood flow by providing a smooth transition between the first, second, and third sections.

[0026] According to a second aspect, there is provided a stent system comprising: a first stent that is the stent for crossing over the common iliac arteries according to any preceding aspect; and a second stent, the second stent being transitionable from a radially compact state to a radially expanded state; wherein, when the first stent is in the radially expanded state and the second stent is in the radially expanded state, the second stent has a first end and a second end, wherein the second end is shaped to engage with the aperture of the first stent to allow the first stent to connect to the second stent.

[0027] The two stents of this stent system may thus work together to form an inverted-Y shape that sits within the aorta, the right common iliac artery, and the left common iliac artery, and provides a clear path for bloodflow from the aorta into the common iliac arteries.

[0028] The native unobstructed aorta has a generally oval cross section towards its inferior end, where the aorta joins to the aortoiliac bifurcation. In aortoiliac occlusive disease, this oval cross-sectional shape of the aorta may be altered by the presence of plaques and built-up in the aorta. The first end of the second stent may have an oval cross section. The oval cross section may be shaped so as to generally match the size and shape of the native unobstructed aorta towards the inferior end of the aorta. In this manner, the second stent may, in the expanded state, provide a flowpath that is substantially similar to the unobstructed native aorta.

[0029] The first end of the second stent may have a size and shape that is substantially the same as the size and shape of the aperture of the first stent. In this manner, the first sent and second stent may connect to each other and in such a way that the flowpath that is provided by the two stents, once implanted, may be substantially identical to a native unobstructed (i.e. healthy) aorta, aortoiliac bifurcation, and common iliac arteries of the patient.

[0030] That is, the system, when implanted in a patient, may have a shape that allows blood flow in the aorta / aortoiliac bifurcation / common iliac arteries, wherein the shape is substantially identical to a native unobstructed aorta / aortoiliac bifurcation / common iliac arteries. Put another way, the system may restore the original, unobstructed, shape of this region of arteries for a patient. Angiomed GmbH & Co .Medi zintechnik KG HE REF : 258593 t! 0 / v9

[0031] The first stent may comprise a chimney portion wherein the aperture is formed at an end of the chimney portion. This may provide a larger contact area between the two stents of the stent system, and thus improve their connection to one another and prevent undersirable relative movement of the stents. Optionally, the second stent may solely contact the first stent solely at the chimney portion. As the second stent does not extend below the chimney portion, the second stent may avoid generating any turbulence in the section of the stent system where a single stream of blood (from the aorta) splits into two streams (one into each iliac artery).

[0032] When the second stent is in the expanded state, the second end of the second stent may have an oval cross-sectional shape. This may match with an oval cross sectional shape of the aperture. In this manner, the system may provide a blood flowpath that is substantially identical to a native unobstructed aorta / aortoiliac bifurcation.

[0033] The second end of the second stent may be flared outwards. This may allow the second stent to engage the aperture by having a flared section larger than the aperture, such that the aperture acts as a collar around the second stent.

[0034] In particular, the system preferably has no struts or protrusions that impede blood flow through the stents. For example, an uncovered stent, in the expanded configuration, may have multiple small holes in the wall of the stent that could allow blood to flow through the holes. However, the edges of these holes would impede blood flow in much the same way that a sieve may allow water to flow therethrough, but the sieve still nonetheless impedes or disrupts the flow to some extent. Thus, blood flowing through such small holes in the wall of a stent would be, to some extent, impeded.

[0035] The stent of the first aspect may be delivered via catheter. Thus, according to a third aspect of the present invention, there is provided a catheter comprising: a catheter tube having a proximal end and a distal end; and the stent according to the first aspect, wherein the stent is in its radially compacted state and is located within the catheter tube.

[0036] A catheter may provide a convenient means for delivering the stent to the iliac arteries.

[0037] The stent system may also be delivered via catheter. Thus, according to a fourth aspect of the present invention, there is provided a catheter comprising: a catheter tube having a proximal end and a distal end; and the stent system according to the second aspect, wherein the first stent is in its radially compacted state and is positioned within the catheter tube and the second stent in its radially compacted state and is positioned in Angiomed GmbH & Co .Medi zintechnik KG HE REF : 258593 t! 0 / v9 the catheter tube; wherein the first stent is positioned ahead of the second stent such that, out of the first and second stents, the first stent is closer to the distal end of the catheter tube.

[0038] With this arrangement of the two stents within the catheter, the first stent may be implanted across the common iliac arteries and expanded, and then the second stent may be inserted partially through the aperture of the first stent and expanded. In this manner, the second stent connects to the first stent forming the stent system having an inverted Y-shape. Having both stents in one catheter may increase the speed of the implantation operation. Further, both stents may be implanted using only a single access, e.g. a femoral access. This is in contrast to kissing stents which typically require two accesses, one in each femoral artery, to implant the two stents.

[0039] According to a fifth aspect of the present invention, there is provided a method of implanting a stent in the common iliac arteries, the stent being transitionable between a radially compacted state and a radially expanded state, wherein the stent further comprises a first open end and a second open end, and wherein the wall defines a central lumen of the stent between the first open end and the second open end; wherein in at least the radially expanded state an aperture is formed in the wall at a location between the first end and the second end of the stent, and wherein in the radially expanded state the aperture has a contour which is suitable for aligning with an open end of another stent for branching off the central lumen of the stent through the open end of that other stent, so that a flow path between the central lumen and the branched-off lumen is free from obstructions; the method comprising: advancing a catheter containing the stent in the radially compacted state through a patient’s vasculature to a position at or proximate the aortoiliac bifurcation; imaging the stent to determine a position and orientation of the stent; and transitioning the stent to the radially expanded state, such that, in the radially expanded state: the first end sits within one of the common iliac arteries, the second sits within another of the common iliac arteries, and the aperture faces towards the aorta.

[0040] This method may allow treatment of aortoiliac occlusive disease by restoring patency of occluded blood vessels using the stent.

[0041] According to a sixth aspect, there is provided a method of implanting a stent system in an aorta using the catheter of the fourth aspect; the method comprising: advancing the distal end of the catheter tube through a patient’s vasculature; positioning the first stent in a position in which the first stent crosses over the common iliac arteries and in which the aperture, when the first stent is transitioned to its radially expanded state, will face Angiomed GmbH & Co .Medi zintechnik KG HE REF : 258593 t! 0 / v9 towards the aorta; transitioning the first stent to its radially expanded state; inserting the second stent partially through the aperture; and transitioning the second stent to its radially expanded state, such that the second end of the second stent is located inferior of the aperture, within the first stent, and the first end of the second stent is located superior to the aperture, outside the first stent.

[0042] This method may also allow treatment of aortoiliac occlusive disease by restoring patency of occluded blood vessels using the stent.

[0043] Brief Description of the Figures

[0044] These and other aspects are now described in the detailed description, by way of example only and with reference to the drawings in which:

[0045] Figures 1 A and 1 B depict kissing stents located in and around the aortoiliac bifurcation;

[0046] Figure 2A shows a stent crossing over the common iliac arteries;

[0047] Figure 2B shows a plan view of the stent in the expanded state;

[0048] Figure 2C shows a perspective view of the stent outside the body;

[0049] Figure 2D shows struts forming the wall of the stent of Figures 2A-C;

[0050] Figure 3A shows another design of stent crossing over the common iliac arteries;

[0051] Figure 3B shows a plan view of the stent of Figure 3A in the expanded state;

[0052] Figure 3C shows a perspective view of the stent of Figure 3A outside the body;

[0053] Figure 3D shows plan view of a stent in the expanded state and having crossing struts; Figure 3E shows a side view of the stent of Figure 3D in the expanded state and with the crossing struts flared outwards;

[0054] Figure 4 shows a stent in the aorta, the stent having a flared end;

[0055] Figure 5 shows a stent system comprising the stent of Figure 4 and a stent crossing over the common iliac arteries;

[0056] Figure 6 shows a catheter containing two stents;

[0057] Figure 7A shows a stent for the aorta having flared-outward struts;

[0058] Figures 7B and 7C show the stent of Figure 7A connected to different designs of a strut crossing over the common iliac arteries;

[0059] Figure 8A shows another design of stent for crossing over the iliac arteries;

[0060] Figure 8B shows a side-view of the stent of Figure 8A with an additional chimney portion;

[0061] Figure 9A shows a 3D model of a stent for crossing over the common iliac arteries; and

[0062] Figure 9B shows a plan view of the stent of Figure 9A. Angiomed GmbH & Co .Medi zintechnik KG HE REF : 258593 t! 0 / v9

[0063] Detailed Description

[0064] References herein to native unobstructed vessel may be taken to refer to a healthy patient who does not have any deposits, lesions, aneurism, or obstruction in said vessel.

[0065] Figure 1A depicts the (descending) aorta 100, towards its inferior end where the aorta 100 merges into the aortoiliac bifurcation 102, which then splits into the two common iliac arteries 104,106. Figure 1A, along with Figures 1 B, 2A, 3A, 4, and 5, are all drawn as if the patient is facing towards the reader, and thus the iliac artery on the left side of the image is the patient’s right common iliac artery 104. Similarly, the iliac artery on the right side of the image is the patient’s left common iliac artery 106. Lesions or deposits 108 are depicted at various locations in the aorta 100, aortoiliac bifurcation 102, and common iliac arteries 104, 106. The deposits 108 obstruct bloodflow through this region of the vasculature and may lead to aortoiliac occlusive disease. Symptoms of aortoiliac occlusive disease may include pain, numbness, cramping in the lower limbs, gangrene, and erectile dysfunction. In many cases, the disease may be treated by restoring patency of these blood vessels (100-106) using stents so that blood may again flow freely through these vessels.

[0066] Figure 1A depicts the end result of a known procedure in which so-called “kissing stents” 110, 112 have been implanted in the patient. One kissing stent 110 extends from the aorta 100, through the aortoiliac bifurcation 102, and into the right common iliac artery 104. The other kissing stent 112 extends from the aorta 100, through the aortoiliac bifurcation 102, and into the left common iliac artery 106. The superior ends of the two kissing stents 110,112 are generally immediately adjacent one another or just touching (“kissing”) one another. These kissing stents 110,112 provide a clear path for blood flow out of the aorta 100 and into the common iliac arteries 104,106. That is, the kissing stents 110, 112 push aside deposits 108a-c that had previously built-up and were impeding blood flow in this region.

[0067] In the example of Figure 1A, the deposits 108a, 108b extend up into the inferior end of the aorta 100.

[0068] In the example shown in Figure 1 B, the deposits 108d,108e do not extend into the inferior end of the aorta 100. As such, in this example, kissing stents 1 10,112 may be placed lower down, such that their superior ends are in the aortoiliac bifurcation 102. Other than this, the examples shown in Figures 1 A and 1 B are similar to one another. Angiomed GmbH & Co .Medi zintechnik KG HE REF : 258593 t! 0 / v9

[0069] Kissing stents are part of a known procedure for restoring patency past deposits 108 in and around the aortoiliac bifurcation 102. The native unobstructed descending aorta 100 has a generally circular cross section which changes to a more oval cross section as it approaches the aortoiliac bifurcation 102. When two kissing stents 110, 112 are implanted, the kissing stents typically provide two flowpaths, each having a circular cross-sectional area. This means that the blood flowing through the aorta passes from one circular or oval cross sectional passage (i.e. the aorta) into two distinct circular passages (i.e. the kissing stents). This sudden change may cause undesirable turbulence around the superior ends of the kissing stents, which turbulence can lead to additional deposits forming in this region. It is desirable to provide a smooth transition for blood flowing through the aorta and into the common iliac arteries to prevent the buildup of future deposits.

[0070] A “stent” is typically an uncovered frame of, usually, metal, for keeping open an anatomical vessel such as a blood vessel. A “stentgraft” is typically a stent that has a fluid-impermeable cover along at least part of its length. Stentgrafts may also be called “covered stents”. Throughout the following description, we refer to a “stent” (e.g. stent 40, stent 10), but the description applies equally to stentgrafts / covered stents as well. That is, stent 40 may be either covered or uncovered. Similarly, stent 10 may be either covered or uncovered.

[0071] Figure 2A depicts a stent 40 is crossing over the common iliac arteries 104,106. The stent 40 has a radially expanded state and a radially compacted state. The stent 40 is transitionable at least from the radially compacted state to the radially expanded state. That is, the stent 40 may be designed to only be expanded once. Alternatively, the stent 40 may be transitionable from its compacted state to its expanded state, and from its expanded state to its compacted state.

[0072] The stent 40 is shown in Figure 2A in the radially expanded state that it has after being implanted in a patient.

[0073] The stent 40 has a first end 42 and a second end 44 and a wall 46 extending between the first and second ends 42,44. The wall 46 defines a central lumen 41 of the stent 44, where the central lumen 41 extends from the first end 42 to the second end 44 of the stent 40. The first end 42 sits in the right common iliac artery 104 and the second end 44 sits in the left common iliac artery 106. The stent 40 has an aperture 48 in its wall 46, the aperture located between the two ends 42,44, and, when implanted in a patient, the aperture 48 is oriented to be facing upwards towards the aorta 100. The Angiomed GmbH & Co .Medi zintechnik KG HE REF : 258593 t! 0 / v9 stent 40 may be termed, for example, a crossover stent or iliac stent or crossover iliac stent etc.

[0074] The aperture 48 allows blood to flow from the aorta 100 and into the central lumen 41 of the stent 40. The structural strength of the stent 40, once implanted and expanded, means the stent 40 pushes back or compresses deposits 108d-f to provide a wider path for bloodflow than existed immediately prior to the stent’s implantation. The blood from the aorta 100 may then flow through the central lumen 41 towards the first end 42 and towards the second end 44. The stent 40 therefore provides a flowpath for blood exiting the inferior end of the aorta 100 and going into each of the common iliac arteries. This flowpath is preferably substantially the same as the flowpath in the native unobstructed common iliac arteries 102,104, i.e. this flowpath is preferably substantially the same as in a healthy patient who has no lesions, deposits 108 etc. in or around the aortoiliac bifurcation 102. Depending on the precise positioning of the stent 40, which may be decided based on clinical indications, the aperture 48 may be generally located within the inferior end of the aorta 100 or located within the aortoiliac bifurcation 102, or partially within each of the aorta 100 and aortoiliac bifurcation 102. As discussed below, the aperture 48 is not necessarily precisely planar in 3D space. In some designs however, the aperture may be defined substantially entirely within a single 2D plane.

[0075] In the expanded state shown in Figure 2A, the aperture 48 provides a substantially unobstructed path for blood from the aorta 100 into the central lumen 41 . That is, there are no struts or other pieces of the stent that cross or impinge through the aperture 48 that would inhibit blood flow or induce turbulence in blood flow etc. Preferably, the aperture 48 has a size and shape that is substantially similar to the native, unobstructed aorta 100 / aortoiliac bifurcation 102. The inferior end of the native, unobstructed aorta 100, where it meets / merges into the aortoiliac bifurcation 102, typically has an oval cross-sectional shape, i.e., an oval shape in the plane transverse to the direction of blood flow. The oval shape of the aorta 100 here is oriented such that the (2D) oval lies in the transverse plane of the patient and the longer (major) axis of the oval is aligned in the lateral direction of the patient, i.e., from their left side to their right side. The minor axis of the oval is aligned with the anterior-posterior axis of the patient, i.e. from their front to their back.

[0076] The aperture 48 preferably has an oval cross-sectional shape, when the stent 40 is in the radially expanded state, and when the aperture 48 is viewed in a plan view along the direction of blood flow out of the aorta 100. The edge of the aperture 48 may not be precisely planar and may, for example, form a generally saddle-shape (e.g., Angiomed GmbH & Co .Medi zintechnik KG HE REF : 258593 t! 0 / v9 hyperbolic paraboloid shape), depending on the precise curvature of the stent 40 once implanted. However, the shape of the aperture projected onto a 2D plane that is transverse to the direction of blood flow will be preferably oval shaped. Put another way, when viewed along the direction of blood flow through the aorta (i.e. “looking downwards towards the aperture 48”), the aperture 48 appears to have an oval shape. In other designs of stent, the shape of the aperture projected onto a 2D plane transverse to the direction of blood flow may be circular. Further references herein to “the shape of the aperture” are referring specifically to its 2D shape as defined by the projection of the aperture onto a 2D plane that is transverse to the direction of blood flow. This plane may be equivalently defined as the plane that is transverse to an axis that passes through a centerpoint of the aperture and through a point of the stent diametrically opposite to the centerpoint.

[0077] The oval shape may have a major axis Ma40 and a minor axis Mi40. The major axis Ma40 is generally aligned with a longitudinal axis of the stent 40 that extends from the first end 42 to the second end 44. As such, when the stent 40 is implanted across the common iliac arteries 104,106, the major axis Ma40 of the aperture 48 is substantially aligned with the major axis of the oval shape of the native unobstructed aorta 100 at its inferior end.

[0078] The first end 42 and second end 44 of the stent 40 may each have a generally circular cross-sectional shape. In Figure 1A, the second end 44 is shown having a circular cross-sectional shape with a radius r44. The first end 42 is shown having a circular cross-sectional shape with a radius r42. These two radii r44 and r42 may be equal or may be different. When implanted, the stent 40 has a generally curved shape between its first end 42 and second end 44. That is, the central lumen 41 has a curved shape.

[0079] The reader should note that, when the stent 40 is in the radially compact state, the aperture 48 may appear to have an entirely different shape or may even not be clearly discernible by eye.

[0080] In the expanded state, the edge of the aperture 48 may have different configurations, for example, struts that make up the wall 46 of the stent or joins between two struts. This may therefore make the edge of the aperture deviate slightly from a precisely smooth curve but this deviation does not obscure the overall shape of the aperture. In other designs, the edge of the aperture is clearly defined e.g. by a wire or by a cover, such that the edges of the oval / circular aperture 48 are smooth. Angiomed GmbH & Co .Medi zintechnik KG HE REF : 258593 t! 0 / v9

[0081] The stent 40 may optionally have one or more radiopaque markers 49a, b. These may be mounted on the wall 46 or may themselves form part of the wall 46. These may assist in orienting the stent 40 during the implantation procedure. In the example shown in Figure 2A, the radiopaque markers 49a, b are each located on an edge of the aperture 48 and substantially diametrically opposite one another. However, other placements are also envisaged. For example, one or more radiopaque markers may be placed on a side opposite to the aperture 48 (i.e. “underneath” the aperture, when the stent 40 is implanted), or may be placed near the ends 42,44 of the stent 40. Where present, the radiopaque markers are placed such that a user (e.g. physician), viewing the radially-compact stent 40 under radio imaging, can determine which orientation the aperture 48 will have after the stent 40 has been transitioned to its radially expanded configuration. The placement of the radiopaque markers relative to the aperture may, for example, be indicated on packaging of the stent 40.

[0082] Thus, by way of example only, if the stent 40 has radiopaque markers that are opposite the place where the aperture 48 will be when the stent 40 is expanded, the user (e.g. physician) may adjust the orientation of the stent 40 such that the radiopaque markings appear at an inferior-most point of the aortoiliac bifurcation 102 before transitioning the stent 40 to its radially expanded configuration. If the radiopaque markers 49a, b are placed on the edge of the aperture, then the physician will adjust the orientation of the stent such that the radiopaque markers appear uppermost, closest to the aorta, before transitioning the stent to its radially expanded state.

[0083] As will be seen later, the radiopaque markers 49a, b may also assist in positioning other components, including another stent, relative to the stent 40.

[0084] Figure 2B shows a plan view of the stent 40 in its expanded configuration and outside the body. For the sake of easy explanation, the stent 40 in this Figure is depicted as having a straight centerline from its first end to its second end, i.e. the stent is “flat”. However, the stent 40 may be designed to have an inherent curvature of the centerline, so that the generally-cylindrical shape of the stent bends. This may allow the stent 40 to more-closely conform to the bend between the common iliac arteries. This plan view is taken along a line that is normal to a centerpoint of the aperture 48. In this Figure, the stent 40 is generally straight. That is, a centerline of the central lumen 41 is generally straight between the first end 42 and the second end 44.

[0085] Figure 2C shows the same stent as Figure 2B but now in perspective view, substantially side-on. In Figure 1 C, the saddle-shape of the edge of the aperture 48 may be discerned. From this Figure, it can be seen that the stent 40 in the expanded Angiomed GmbH & Co .Medi zintechnik KG HE REF : 258593 t! 0 / v9 configuration has a generally cylindrical geometry and the aperture 48 has been essentially “cut-out” from this cylinder.

[0086] The stent 40 may be formed of a plurality of struts 22. Together these struts 22 may form a net or scaffold that defines the overall shape of the stent 40. The net or scaffold therefore has a plurality of holes 18 between the struts 22. In other designs, the stent 40 may be made from a solid sheet of material in which many holes 18 have been cut so as to define struts 22 as the material between the holes, wherein the holes 18 provide the necessary flexibility for the stent 40 to have a radially compacted state and a radially expanded state, and to be transitionable between these two states. In either case, in the expanded state, these holes 18 are clearly visually distinguishable from the aperture 48 and from either end 42,44 of the stent 40 in both shape and size.

[0087] Each hole 18 has a hole surface area that is substantially smaller than a surface area of the aperture 48 when the stent 40 is in the radially expanded configuration. That is, in the radially expanded state, the aperture 48 is clearly distinguishable from every one of the holes 18. In one example, the aperture surface area 48 is at least twice as large as the surface area of any one of the holes 18. In other examples, the aperture surface area is at least three times, at least four times, or at least ten times larger than a surface area of any of the holes 18.

[0088] The stent 40 may additionally include a cover 23 that extends over the struts 22 and thereby blocks the holes 18. The cover 23 may extend over all of all of the struts 22 of the stent 40. Alternatively, the cover may extend over some but not all of the struts 22. The cover 23 may be sutured or otherwise attached to multiple of the struts 22, to fix the cover. The cover 23 does not extend over the first end 42 nor the second end 44 of the strut, such that the central lumen 41 may remain unobstructed. The cover 23, where present, also has a cover aperture that overlaps the aperture 48 and is substantially the same size and shape as the aperture 48 when the stent 40 is in the radially expanded state. In this manner, the cover 23 does not obstruct or substantially overlap any of the aperture 48 either, so that the aperture also remains unobstructed.

[0089] In another design of stent 40, shown in Figures 3A-C, the wall 46 may be shaped to have a chimney portion 50 wherein the aperture 48 is formed at a first end 51 of the chimney portion 50 that is distalmost from a centerline of the stent 40 that joins the first end 42 to the second end 44. That is, compared to a stent 40 that is cylindrical or a cylinder bent around a curved path (as when the stent 40 crosses over the common iliac arteries), the chimney portion 50 sits proud of the cylindrical shape (or cylinder bent around a curved path). This chimney portion 50 therefore places the aperture 48, Angiomed GmbH & Co .Medi zintechnik KG HE REF : 258593 t! 0 / v9 when implanted, at a location closer to the inferior end of the aorta 100 than the aperture 48 of stents 40 that lack the chimney portion 50. The chimney portion 50 may include wrapped with ePTFE membrane, for example.

[0090] By way of non-limiting example, the chimney portion thus formed may have a height of 10 mm and may define an (oval) aperture 48 having a maximum diameter of 25 mm. Other sizes are envisaged however.

[0091] Again, the stent 40 may be designed such that the aperture 48 in the chimney portion 50 has a generally oval or circular shape when viewed in a plan view taken along an axis normal to a centerpoint of the aperture 48 (i.e., “when looking down towards the stent from the aorta 100”).

[0092] In Figure 3C, the stent 40 is shown in a flat configuration, outside the patient body. The stent 40 is generally cylindrical between its first end 42 and second end 44 except for the chimney portion 50 which sits proud of the otherwise-cylindrical shape of the stent 40. The chimney portion 50 may not be present or may not be easily discernible while the stent 40 is in the radially compacted state. Radiopaque markers 49a, b may be provided on the chimney portion 50 to assist the user (e.g. physician) in determining the orientation stent 40 while it is in the radially compacted state, so that, when the stent is transitioned to the radially expanded state, the aperture 48 has the correct orientation relative to the aorta 100.

[0093] As shown in Figures 3D and 3E, the chimney portion 50 may be formed by a series of crossing struts 52. During implantation, the stent 40 may be expanded to its radially- expanded configuration and the crossing struts 52 lie flat across an initial aperture 48 in the wall 46, as shown in Figure 3D. The crossing struts 52 may then be pushed outwards, i.e. upwards towards the aorta 100, by an instrument, so that they flare outwards and their tips define a generally circular or oval shape (when viewed in plan view, looking downwards). The tips of the crossing struts 52 thus define the aperture 48 of the stent 40, in these examples. The stents 40 shown in Figures 3A-C may include the crossing struts 52 of Figures 3D,3E as a way of forming the chimney portion, with the addition of a cover that covers the crossing struts 52 and provides a smooth surface of the chimney portion 50.

[0094] The stent 40 may be implanted using a catheter. The stent 40 may be self expanding (SX) or balloon expanded (BX). Angiomed GmbH & Co .Medi zintechnik KG HE REF : 258593 t! 0 / v9

[0095] Figure 4 depicts a stent 10 that sits in the aorta 100 and extends into the aortoiliac bifurcation 102. The stent 10 has a radially compacted state and a radially expanded state. The stent 10 is transitionable at least from the radially compacted state to the radially expanded state. That is, the stent 10 may be designed to only be expanded once. Alternatively, the stent 10 may be transitionable from its compacted state to its expanded state, and from its expanded state to its compacted state. The stent 10 may be termed an aortic stent, for example. The stent 10 may be implanted using a catheter. The stent 10 may be self-expanding (SX) or balloon expanded (BX).

[0096] The stent 10 has a circular cross section at its superior end 12, said cross section having a radius O-|2- The stent 10 has an oval cross section at its inferior end 14. The oval cross section is defined by a radius r1 in the minor axis and a radius r2 in the major axis, where r1 and r2 are different. The stent 10 pushes back deposits 108a,b,c and provides a clear path for blood to flow through the inferior end of the aorta 100 and into the aortoiliac bifurcation 102. As the stent 10 has a circular cross section at the first (superior) end 12, and an oval cross sectional shape at the second (inferior end) 14, the overall stent 10 may be said to have a flared end (i.e. the flared second end 14) or flared shape.

[0097] The stent 10 is preferably implanted such that the radius r1 of the major axis is aligned with the oval cross-sectional shape of a native unobstructed aorta 100 at this location. To assist this, the stent 10 may have radiopaque markers 18,20 that are positioned such that, while the stent is in the radially compacted state, the user (e.g. physician) can determine the orientation that the oval shape of the second end 14 will have after the stent 10 has been transitioned to its expanded state. For example, the radiopaque markers may be placed on diametrically opposite sides of the minor axis. During the implantation procedure for the stent 10, the patient may be imaged along their posterior-anterior axis (i.e. front to back). In the expanded state, the minor axis of the stent 10 should be aligned with this posterior-anterior axis of the patient. When the stent 10 is in the correct orientation, under imaging along the patient’s posterior- anterior axis, the two radiopaque markers may overlap one another and thus appear, under imaging, as a single radiopaque marker. When the stent 10 is not in the correct orientation, the two radiopaque markers may appear separate from one another, i.e. two markers are visible, and the physician therefore knows that the stent 10 is not yet in the correct orientation. Other placements of the radiopaque markers 18,20 are possible. For example, radiopaque markers may be placed at the superior end of the stent 10. Radiopaque markers may be placed on diametrically opposite sides of the major axis; in this case, the correct rotational orientation of the stent 10, under imaging, may be determined when the radiopaque markers are maximally far apart from one Angiomed GmbH & Co .Medi zintechnik KG HE REF : 258593 t! 0 / v9 another. Alternatively, the radiopaque markers may be placed at some point between the two ends 12, 14 of the stent 10.

[0098] The stent 10 described hereinabove in relation to Figure 4 may be used in conjunction with the stent 40 described hereinabove in relation to Figures 2A to 3E. Thus, solely to assist the clarity of the following discussion, the stent 10 of Figure 4 will now be referred to as the “aortic stent 10” and the stent 40 of Figures 2A-3E will be referred to as the “iliac stent 40”.

[0099] As shown in Figure 5, the aortic stent 10 may engage with iliac stent 40 at the aperture 48. The aortic stent 10 passes through the aperture 48 such that the flared end 14 of the aortic stent 10 sits inside the central lumen 41 of the iliac stent 40. In the implanted state, the first end 12 of the aortic stent 10 sits in the (inferior end of the) aorta 100, the first 42 end of the iliac stent 40 sits in the right common iliac artery 104, and the second end 44 of the iliac stent 40 sits in the left common iliac artery 106. The two stents 10,40 together may thereby provide an unobstructed, non-turbulent, flow path from the aorta 100, through the aortoiliac bifurcation 102, into the common iliac arteries 104, 106. That is, the stents 10,40 may work together as a system 60 to restore patency of blood flow in this region.

[0100] The system 60 may be implanted via a catheter, as shown in Figure 6. Figure 6 shows the catheter 80 having a distal end 62 and a proximal end 64. In use, the distal end 62 is inserted via an access into the patient’s vasculature (e.g. an access in the femoral artery) and the catheter 80 is advanced through the vasculature. The iliac stent 40 is located in the catheter in its radially compacted state. The aperture 48 is depicted solely for convenience and, as mentioned previously, the aperture 48 may not be present or discernible by eye while the iliac stent 40 is in the radially compacted state. The aortic stent 10 is located in the catheter in the radially compacted state. The iliac stent 40 is located closer to the distal end 62 of the catheter 80 than the aortic stent 10 is. The first end 12 of the aortic stent 10 is placed closest to the iliac stent 40 within the catheter, and the second end 14 of the aortic stent 10 is furthest from the iliac stent 40. This means that, during the implantation procedure, the aortic stent 40 is implanted first, followed by the aortic stent 10. The iliac stent 40 therefore also functions as a stopper for the aortic stent 10 while both stents 10,40 are within the catheter.

[0101] In the art, catheter diameters and stent diameters are typically measured in units of French, where 1 French = 1 / 3 mm, i.e. 1 French « 0.33 mm. The aortic stent 10 may optionally be 10 French in the radially compacted state and may optionally expand to a diameter of 25 mm (75 French), at the first end 12, in the radially expanded state. Angiomed GmbH & Co .Medi zintechnik KG HE REF : 258593 t! 0 / v9

[0102] The iliac stent 40 may optionally be 8 French in the radially compacted state and may optionally expand to a diameter of 12 mm (36 French) in the radially expanded state. As discussed below, the iliac stent 40 may have sections of different diameters when in the radially expanded state. As discussed above, the aortic stent 10 has a flared end and this may be larger than the 25 mm measurement discussed above.

[0103] The access may, by way of non-limiting example, be in the patient’s leg, downstream of the right common iliac artery. A guidewire 70 may be inserted first, to guide the catheter 80 as it is advanced upstream towards the aortoiliac bifurcation 102.

[0104] Once the catheter 80 is in position, the iliac stent 40 is positioned first, under imaging. When the user (e.g. physician) determines (e.g. via radiopaque markers 49a, b) that the radially compacted iliac stent 40 is in the correct orientation, the iliac stent 40 is transitioned to its radially expanded state, such that the aperture 48 faces upwards towards the aorta 100. As before, the iliac stent 40 may be self-expanding or may be transitioned to its radially expanded state using a balloon (not shown) that is located in the catheter 80. The catheter 80 may then be advanced through the aperture 48. In stents 40 having crossing struts 52, the crossing struts 52 may be pushed by the catheter 80 into their correct position (see e.g. Figure 3E) to form the aperture 48. Alternatively, the aortic stent 10 may be pushed out from the distal end of the catheter 80 and the aortic stent 10 may push the crossing struts 52 into their correct position. In cases where the crossing struts 52 are not present, either the catheter and / or the aortic stent may extend through the aperture 48.

[0105] The aortic stent 10 may then be positioned such that the second end 14 of the aortic stent 10 is located inside the iliac stent 40, and the first end 12 sits within the aorta 100, and the aortic stent 10 extends through the aperture 48. The aortic stent may then be transitioned to its radially expanded state. As before, the aortic stent 10 may be selfexpanding or may be transitioned to its radially expanded state using a balloon (not shown) that is located in the catheter 80. The stents 10,40 may be designed such that the cross-sectional area of the flared second end 14 is greater than a cross sectional area of the aperture, such that the aortic stent 10 cannot pull out from the iliac stent 10 without deform ing / damaging one or both stents 10,40. In this manner, the two stents 10,40 may be firmly connected together to form the overall system 60. When the two stents 10,40 are connected together in their radially expanded state, they form the shape of an inverted-Y. Use of the catheter 80 containing the two stents 10,40 of the stent system 60 allows two stents 10,40 to be placed consecutively in one procedure and via one access. The size(s) of each stent 10,40 may be selected prior to the Angiomed GmbH & Co .Medi zintechnik KG HE REF : 258593 t! 0 / v9 procedure according to the patient’s physiology. That is, the aortic stent 10 may have a different (average) diameter than the (average) diameter of the iliac stent 40.

[0106] In some examples, the aortic stent 10 may only contact the chimney portion 50 of the iliac stent. That is, in these examples, the chimney portion provides a primary function of anchoring the stents 10,40 together.

[0107] The radiopaque markers 18,20 of the aortic stent 10 may, in some systems 60, be used in conjunction with radiopaque markers 49a, b on the iliac stent 40, to ensure proper positioning of the stents 10 relative to one another and relative to a patient’s anatomy before they are transitioned to their respective expanded states.

[0108] Figures 7A-C show another design of the aortic stent 10 in which the flared second end 14 is formed by a plurality of struts 19. The struts 19 flare outwards compared to the generally cylindrical shape of the rest of the stent 10. Some of said struts 19 may be formed of radio-transparent material and others of said struts 19 may be formed of radiopaque material, such that these other struts provide the radiopaque markers 18,20 discussed hereinabove.

[0109] These struts 19 may sit inside the iliac stent 40. These may sit inside an iliac stent 40 that has a chimney portion (as shown in Figures 7B and 7C). The chimney portion 50 may be formed by bare crossing struts 52, as shown in Figure 7B or may be a covered chimney portion (which may or may not include crossing struts 52 as well) as shown in Figure 7C. Alternatively, these may sit inside an iliac strut 40 lacking a chimney portion, i.e. the stent 40 shown in Figures 2A-C. That is, the aortic stent 10 may be used with iliac stents 40 that do have a chimney portion 50 and with iliac stents 40 that do not have a chimney portion 50.

[0110] The stent 40 described herein above may be used standalone. This may be advantageous in cases where there are no (or minimal) deposits 108 in the aorta, and the stent 40 is only needed to treat deposits in the aortoiliac bifurcation and / or common iliac arteries.

[0111] The stent 40 described hereinabove may be used in combination with the stent 10 in a system 60. This may be particularly advantageous in cases where there are deposits 108 in the aorta and in the aortoiliac bifurcation and / or common iliac arteries.

[0112] As discussed above, the two stents 10,40 that form the system 60 may be implanted in one procedure and via one access. This may optionally improve the healing time Angiomed GmbH & Co .Medi zintechnik KG HE REF : 258593 t! 0 / v9 and reduce the infection risk compared to procedures requiring two or more accesses. For example, implanting kissing stents typically requires one access in the left leg and one access in the right leg.

[0113] A further design of the stent 40 (“iliac stent”) is shown in Figure 8. In this design, the stent 40 broadly comprises three sections 54,56,58, where the middle (second) section 56 has a larger width than either of the other two sections 54,58. In greater detail, the first section 54 includes the first end 42 of the stent and extends up to the second section 56. The first section 54 has a first width and this may be, for example, twice the radius r42. The first section may be substantially cylindrical. The first section transitions smoothly, via a first transition section 55, into the second section 56. The second section 56 has a larger width than the first section 54. The second section 56 contains the aperture 48. In the example shown, the aperture is circular when viewed in plan view along a direction normal to a centerpoint of the aperture 48. In this view, the aperture has a diameter 48d. Of course, the aperture may be oval instead. The second section transitions smoothly, via a second transition region 57, into the third section 58. The third section 58 has a smaller width than the second section 56. The third section 58 may by substantially cylindrical and may, for example, have a diameter equal to twice the radius r44. By way of non-limiting example, the (circular) aperture may have a diameter of 25 mm. In some cases, this may be larger than the widths of either the first section 54 and / or the third section 58.

[0114] The stent 40 of Figure 8 has a cover 23 that is translucent, such that the viewer may also see the struts 22 and the holes 18 between the struts 22. The struts 22 together may be considered to form a mesh. In the first section 54 and third section 58, the mesh is relatively fine such that the holes 18 between the struts are correspondingly small. In the second section 56, the mesh is relatively coarse, such that the holes 18 in this region are somewhat larger. In any case, all holes 18 are substantially smaller than the aperture. They also typically do not have a circular or oval shape. Further, in this example, the struts 22 are covered by the cover 23, such that the aperture 48 is clearly defined as the only open aperture between the two ends 42,44 that allows blood flow therethrough. Having the stent 40 divided into three sections in this way may allow the first and third sections 54,58 to fit snugly in the comparatively-narrow iliac arteries, and the wider second section to sit snugly within the aortoiliac bifurcation 102 and to provide a larger aperture 48 than would be possible with a purely-cylindrical stent design. The different sections may be made of different materials and of different designs. For example, the first and third sections 54,58 may be configured to be selfexpanding (SX) while the second section is configured to be balloon-expanded (BX). Angiomed GmbH & Co .Medi zintechnik KG HE REF : 258593 t! 0 / v9

[0115] Figure 8B shows a side view of just the second section 56 of Figure 8A, with the addition of a chimney portion 50. The chimney portion 50 has a plurality of radiopaque markers 49 (i.e. directly analogous to radiopaque markers 49a, b, described hereinabove) formed into two rows. The dashed line at the base of the chimney portion 50 shows the outline of the cylindrical shape that the second section would have in the absence of the chimney portion 50. That is, the dashed line does not depict a real physical feature, but merely helps to show the level above which the chimney portion 50 is standing proud. The radiopaque markers may be of any suitable material. Tungsten is one suitable material. Gold is another.

[0116] Any of the stents 10,40 descirbed hereinabove may be made of any suitable material. For example, Ninitol™ is commonly used in the art for the struts of a stent. The cover 23, if present, may be made of ePTFE, for example. The outer edge of the aperture 48 may be defined by a wire that, in the expanded state, defines the circular or oval cross sectional shape of the aperture 48.

[0117] Where present, the cover 23 may constrain the maximum diameter of the stent 10,40 at any given location or across the whole of the stent 10,40. That is, the struts forming the stent might theoretically allow expansion of the stent to a size of X mm (in some dimension), except that the cover 23 prevents the stent from reaching X mm in that dimension. The cover 23 may therefore be made of a relatively inextensible material that prevents further expansion of the stent once the cover becomes taught.

[0118] In some designs of the system 60, the stent 40 may be covered and the other stent 10 may be uncovered, or vice versa. Alternatively, both stents may be covered. Alternatively, both stents may be uncovered.

[0119] Figure 9A shows a 3D image of a stent 40 in which the struts 22 are clearly visible. The first end 42 and second end 44 are clearly marked. The reader will note that the distance between the first end 42 and the side of the aperture 48 nearest the first end is larger than the distance between the second end 44 and the side of the aperture 48 nearest the second end. That is, the aperture 48 may be situtated in the middle, between the two ends, or the aperture 48 may be situated closer to one end or the other.

[0120] Figure 9B shows a top-down view of the stent 40 of Figure 9A. The oval shape of the aperture 48 is clearly visible in this figure, as are the struts 22.

Claims

Angiomed GmbH & Co .Medi zintechnik KG HE REF : 258593 t! 0 / v9CLAIMS:1 . A stent for crossing over the common iliac arteries, the stent being transitionable between a radially compacted state and a radially expanded state; wherein the stent further comprises a first open end and a second open end, and wherein a wall defines a central lumen of the stent between the first open end and the second open end; wherein in at least the radially expanded state an aperture is formed in the wall at a location between the first end and the second end of the stent, and wherein in the radially expanded state the aperture has a contour which is suitable for aligning with an open end of another stent for branching off the central lumen of the stent through the open end of that other stent, so that a flow path between the central lumen and the branched-off lumen is free from obstructions.

2. The stent according to claim 1 , wherein the aperture is shaped such that, when viewed along an axis that passes through a centerpoint of the aperture and a point on the stent diametrically opposite the centerpoint, the aperture has an oval shape or a circular shape.

3. The stent according to claim 1 or 2, wherein the wall of the stent is formed from one or more struts.

4. The stent according to claim 3, wherein the aperture is not crossed by any struts.

5. The stent according to claim 3, wherein, in the radially expanded state, the one or more struts define a plurality of holes in the wall, each hole having a respective hole surface area; wherein the aperture has an aperture surface area; and wherein the aperture surface area is at least twice as large as a largest of the hole surface areas.

6. The stent according to any preceding claim, wherein the aperture has a smooth outer edge.

7. The stent according to any preceding claim, wherein the stent is a covered stent having a cover, wherein a cover aperture is formed in the cover and the cover aperture overlaps the aperture.Angiomed GmbH & Co .Medi zintechnik KG HE REF : 258593 t! 0 / v98. The stent according to any preceding claim, further comprising one or more radiopaque markers, wherein the radiopaque markers are for determining an orientation of the stent while the stent is in the radially compacted state.

9. The stent according to claim 8, wherein two radiopaque markers are positioned such that, in the radially expanded state, the two radiopaque markers are positioned on opposite sides of the aperture, and optionally wherein the aperture is oval when the stent is in the radially expanded state, and the two radiopaque markers are positioned diametrically opposite one another along either a major axis of the oval or a minor axis of the oval.

10. The stent according to any preceding claim, wherein the wall comprises a chimney portion, wherein, when the stent is in the radially expanded state, the aperture is formed at an end of the chimney portion that is distalmost from a centreline of the stent that extends from the first open end to the second open end.

11. The stent according to claim 9, wherein one or more radiopaque markers are formed on the chimney portion.

12. The stent according to any preceding claim, wherein the stent comprises a first section, a second section, and a third section, wherein the first section extends from the first open end to a first transition region, wherein the third end extends from the second open end to a second transition region, and wherein the second region extends from the first transition region to the second transition region; wherein the second region includes the aperture; wherein every cross sectional area of the second section, taken in a plane transverse to a centerline joining the first open end to the second open end, is: larger than any cross sectional area of the first section, taken in a plane transverse to the centerline, and larger than any cross sectional area of the third section, taken in a plane transverse to a centerline.

13. A stent system comprising: a first stent that is the stent for crossing over the common iliac arteries according to any preceding claim; and a second stent, the second stent being transitionable from a radially compact state to a radially expanded state;Angiomed GmbH & Co .Medi zintechnik KG HE REF : 258593 t! 0 / v9 wherein, when the first stent is in the radially expanded state and the second stent is in the radially expanded state, the second stent has a first end and a second end, wherein the second end is shaped to engage with the aperture of the first stent to allow the first stent to connect to the second stent.

14. The stent system according to claim 13, wherein the first stent comprises a chimney portion and the aperture is formed at an end of the chimney portion; and optionally wherein the second stent solely contacts the first stent solely at the chimney portion.

15. The stent system according to claim 13 or 14, wherein, when the second stent is in the expanded state, the second end of the second stent has an oval cross-sectional shape; and optionally wherein the second end of the second stent is flared outwards.

16. A catheter comprising: a catheter tube having a proximal end and a distal end; and the stent according to any of claims 1 -12, wherein the stent is in its radially compacted state and is located within the catheter tube.

17. A catheter comprising: a catheter tube having a proximal end and a distal end; and the stent system according to any of claims 13 to 15, wherein the first stent is in its radially compacted state and is positioned within the catheter tube and the second stent in its radially compacted state and is positioned in the catheter tube; wherein the first stent is positioned ahead of the second stent such that, out of the first and second stents, the first stent is closer to the distal end of the catheter tube.

18. A method of implanting a stent in the common iliac arteries, the stent being transitionable between a radially compacted state and a radially expanded state, wherein the stent further comprises a first open end and a second open end, and wherein the wall defines a central lumen of the stent between the first open end and the second open end; wherein in at least the radially expanded state an aperture is formed in the wall at a location between the first end and the second end of the stent, and wherein in the radially expanded state the aperture has a contour which is suitable for aligning with an open end of another stent for branching off the central lumen of the stent through the open end of that other stent, so that a flow path between the central lumen and the branched-off lumen is free from obstructions; the method comprising:Angiomed GmbH & Co .Medi zintechnik KG HE REF : 258593 t! 0 / v9 advancing a catheter containing the stent in the radially compacted state through a patient’s vasculature to a position at or proximate the aortoiliac bifurcation; imaging the stent to determine a position and orientation of the stent; and transitioning the stent to the radially expanded state, such that, in the radially expanded state: the first end sits within one of the common iliac arteries, the second sits within another of the common iliac arteries, and the aperture faces towards the aorta.

19. A method of implanting a stent system in an aorta using the catheter of claim 17; the method comprising: advancing the distal end of the catheter tube through a patient’s vasculature; positioning the first stent in a position in which the first stent crosses over the common iliac arteries and in which the aperture, when the first stent is transitioned to its radially expanded state, will face towards the aorta; transitioning the first stent to its radially expanded state; inserting the second stent partially through the aperture; and transitioning the second stent to its radially expanded state, such that the second end of the second stent is located inferior of the aperture, within the first stent, and the first end of the second stent is located superior to the aperture, outside the first stent.

Images