Stent

A stent includes a stent body defining a longitudinal axis and proximal and distal ends and being expandable from a compressed configuration to an expanded configuration. The stent body includes a plurality of stent segments. The stent segments include a first end segment and a second end segment on opposite ends of the stent body and at least one intermediate segment disposed between the first end segment and the second end segment. Each stent segment defines a plurality of cells and a plurality of peaks and valleys. The at least one intermediate segment defines only x number of cells. The first end segment defines at least x+1 number of cells. Each of the cells of the first end segment is substantially equal in size. Each of the at least one intermediate segment and the first end segment defines only y number of peaks and valleys.

TECHNICAL FIELD

This disclosure relates to a medical device and, in particular, to a stent.

BACKGROUND

Stents are widely used for numerous medical applications where the stent is placed in the lumen of a subject and expanded. Stents may be used in the coronary or the peripheral vasculature, as well as other body lumens. In some examples, stents are metal, tubular structures which are passed through a body lumen in a collapsed state. At the point of an obstruction or other deployment site in the body lumen, the stent is expanded to support the lumen. Stents may be self-expanding or balloon-expandable. Self-expanding stents may be inserted in a constrained state into a body lumen via a delivery device and released, such that the unconstrained stent is free to radially expand. A balloon-expandable stent may be positioned on a balloon of a balloon catheter and the stent is may be expanded at the deployment site through inflation of the balloon.

SUMMARY

In some aspects, this disclosure describes example stents, which may be vascular stents or arterial stents. A stent may include a stent body defining a longitudinal axis and proximal and distal ends. The stent body may be expandable from a compressed configuration to an expanded configuration. The stent body may include a plurality of stent segments, including a first end segment and a second end segment on opposite ends of the stent body and at least one intermediate segment disposed between the first end segment and the second end segment. Each stent segment may define a plurality of cells and a plurality of peaks and valleys. The at least one intermediate segment may define only x number of cells. The first end segment, which may be a proximal or distal end segment, may define at least x+1 number of cells. Each of the cells of the first end segment may be substantially equal in size. The at least one intermediate segment and the first end segment may each define only y number of peaks and valleys.

In some examples, the example stents may be formed by a method including selecting an appropriate diameter tubular member, forming the stent pattern described above in a tubular member to form the stent body, incrementally expanding and heat setting the tubular member, and heat setting the tube at its final diameter.

Clause 1: In some examples, a stent comprises a stent body defining a longitudinal axis and proximal and distal ends. The stent body is expandable from a compressed configuration to an expanded configuration. The stent body includes a plurality of stent segments. The stent segments include a first end segment and a second end segment on opposite ends of the stent body and at least one intermediate segment disposed between the first end segment and the second end segment. Each stent segment defines a plurality of cells. Each stent segment defines a plurality of peaks and valleys. The at least one intermediate segment defines only x number of cells. The first end segment defines at least x+1 number of cells. Each of the cells of the first end segment is substantially equal in size. The at least one intermediate segment defines only y number of peaks and valleys. The first end segment defines only y number of peaks and valleys.

Clause 2: In some examples of the stent of clause 1, a portion of the first end segment defining only one cell defines only three peaks, only two valleys, and only two half valleys, on each of two opposing sides of the portion of the first end segment.

Clause 3: In some examples of the stent of clause 1 or 2, a portion of the at least one intermediate segment defining only one cell defines only four peaks, only three valleys, and only two half valleys, on each of two opposing sides of the portion of the intermediate segment.

Clause 4: In some examples of the stent of any of clauses 1-3, the second end segment defines at least x+1 number of cells.

Clause 5: In some examples of the stent of any of clauses 1-4, each of the cells of the second end segment is substantially equal in size.

Clause 6: In some examples of the stent of any of clauses 1-5, a portion of the second end segment defining only one cell defines only three peaks, only two valleys, and only two half valleys, on each of two opposing sides of the portion of the second end segment.

Clause 7: In some examples of the stent of any of clauses 1-6, each of the cells of the at least one intermediate segment are substantially equal in size.

Clause 8: In some examples, a method comprises forming a stent pattern in a tubular member to form a stent body defining a longitudinal axis and proximal and distal ends. The stent body is expandable from a compressed configuration to an expanded configuration. The stent body includes a plurality of stent segments. The stent segments include a first end segment and a second end segment on opposite ends of the stent body and at least one intermediate segment disposed between the first end segment and the second end segment. Each stent segment defines a plurality of cells. Each stent segment defines a plurality of peaks and valleys. The at least one intermediate segment defines only x number of cells. The first end segment defines at least x+1 number of cells. Each of the cells of the first end segment is substantially equal in size. The at least one intermediate segment defines only y number of peaks and valleys. The first end segment defines only y number of peaks and valleys.

Clause 9: In some examples of the method of clause 8, the tubular member comprises shape-memory material.

Clause 10: In some examples of the method of clause 8 or 9, the method further comprises incrementally expanding and heat setting the tubular member.

Clause 11: In some examples of the method of any of clauses 8-10, a portion of the first end segment defining only one cell defines only three peaks, only two valleys, and only two half valleys, on each of two opposing sides of the portion of the first end segment.

Clause 12: In some examples of the method of any of clauses 8-11, a portion of the at least one intermediate segment defining only one cell defines only four peaks, only three valleys, and only two half valleys, on each of two opposing sides of the portion of the intermediate segment.

Clause 13: In some examples of the method of any of clauses 8-12, the second end segment defines at least x+1 number of cells.

Clause 14: In some examples of the method of any of clauses 8-13, each of the cells of the second end segment is substantially equal in size.

Clause 15: In some examples of the method of any of clauses 8-14, a portion of the second end segment defining only one cell defines only three peaks, only two valleys, and only two half valleys, on each of two opposing sides of the portion of the second end segment.

Clause 16: In some examples of the method of any of clauses 8-15, each of the cells of the at least one intermediate segment are substantially equal in size.

Clause 17: In some examples of the method of any of clauses 8-16, a portion of the first end segment defining only one cell defines only two peaks, only two half peaks, and only three valleys on each of two opposing sides of the portion of the first end segment.

Clause 18: In some examples, a method comprises advancing a distal end of a catheter to a treatment site within a patient, wherein a stent is disposed within the catheter; and releasing the stent from the catheter at the treatment site. The stent comprises a stent body defining a longitudinal axis and proximal and distal ends. The stent body is expandable from a compressed configuration to an expanded configuration. The stent body includes a plurality of stent segments. The stent segments include a first end segment and a second send segment on opposite ends of the stent body and at least one intermediate segment disposed between the first end segment and the second end segment. Each stent segment defines a plurality of cells. Each stent segment defines a plurality of peaks and valleys. The at least one intermediate segment defines only x number of cells. The first end segment defines at least x+1 number of cells. Each of the cells of the first end segment is substantially equal in size. The at least one intermediate segment defines only y number of peaks and valleys. The first end segment defines only y number of peaks and valleys.

Clause 19: In some examples of the method of a clause 18, the method further comprises inserting a guide member into a body lumen of the patient; and advancing the distal end of the catheter to the treatment site over the guide member.

Clause 20: In some examples of the method of a clause 18 or 19, a portion of the first end segment defining only one cell defines only three peaks, only two valleys, and only two half valleys, on each of two opposing sides of the portion of the first end segment.

Clause 21: In some examples of the method of any of clauses 18-20, a portion of the at least one intermediate segment defining only one cell defines only four peaks, only three valleys, and only two half valleys, on each of two opposing sides of the portion of the intermediate segment.

Clause 22: In some examples of the method of any of clauses 18-21, the second end segment defines at least x+1 number of cells.

Clause 23: In some examples of the method of any of clauses 18-23, each of the cells of the second end segment is substantially equal in size.

Clause 24: In some examples of the method of any of clauses 18-23, a portion of the second end segment defining only one cell defines only three peaks, only two valleys, and only two half valleys, on each of two opposing sides of the portion of the second end segment.

Clause 25: In some examples of the method of any of clauses 18-24, each of the cells of the at least one intermediate segment are substantially equal in size.

DETAILED DESCRIPTION

A medical stent, e.g., a vascular stent or an arterial stent, may be configured such that certain mechanical characteristics of the stent, such as lateral and radial strength, fracture resistance, and uniform strain distribution, are balanced with stent flexibility in both the longitudinal and radial directions. A stent may be flexible in order to accommodate movement at the implantation site within a patient. For example, a stent may be positioned within a subject's vasculature at or near a subject's joint (e.g., hip, pelvis, knee, elbow, etc.). In these regions, the stent may be subjected to torsion, bending and other mechanical stress. Moreover, stents for use in the venous system such as inferior vena cava (IVC), common iliac, external iliac, and common femoral veins regions require relatively high strength and maximum flexibility, e.g., compared with stents configured for use in other implant sites, such as arterial implant sites.

In some cases, an end of a stent (e.g., a distal or proximal end, or both the distal and proximal ends, which may be terminal ends of the stent) may have different performance requirements than the middle of the stent. Flexibility, radial force (e.g., force in radially outward directions from a center axis of the stent) and lateral force (e.g., force in a single lateral direction), and durability requirements may each be somewhat different for the end of the stent than for the middle. In addition, the end may play a particularly important role with respect to ease of deployment of the stent in a body lumen of a patient and/or deployment accuracy.

The example stents described herein may accomplish particular technical advantages. For example, the modification of at least one end segment of the stent, such that it has a different configuration than the intermediate segments of the stent (located between the end segments), including a greater number of cells (e.g., due to a greater number of struts, a greater number of connectors between struts, or both) than the intermediate segments, may improve ease of deployment and/or deployment accuracy when compared to stents without modification to any of the end segments (with the same configuration in the intermediate segments and the end segments). The configuration of the end segments of the stent may allow the stent to be deployed more smoothly (e.g. may experience less “jump”) from a delivery device (e.g., a delivery catheter), which may allow the stent to be more easily, predictably, and accurately deployed in an intended site within a body lumen of a patient without the stent jumping out of the delivery device (e.g., as an outer sheath is retracted) and away from the intended target site.

The example stents described herein may also accomplish particular technical advantages compared to end segments including the same number of struts but twice the number of evenly sized cells as the intermediate segments. For example, the example stents may have increased flexibility over such designs without substantial reduction in radial or lateral force. With increased flexibility in the end segments, overlapped stents may have smoother flexibility transitions in a region of overlap (e.g., defined by end segments of the overlapped stents) and, therefore, improved durability in an overlapped configuration.

In some examples, a stent includes a stent body defining a longitudinal axis and proximal and distal ends. The stent body may be expandable from a compressed configuration to an expanded configuration. The stent body may include a plurality of stent segments, including a first end segment and a second end segment on opposite ends of the stent body and at least one intermediate segment disposed between the first end segment and the second end segment. Each stent segment may define a plurality of cells and a plurality of peaks and valleys. The at least one intermediate segment may define only x number of cells. The first end segment may define at least x+1 number of cells. Each of the cells of the first end segment may be substantially equal in size. The at least one intermediate segment may define only y number of peaks and valleys. The first end segment may define only y number of peaks and valleys.

In some examples, the example stents may be formed by a method including selecting an appropriate diameter tubular member, forming the stent pattern described above in a tubular member to form the stent body, incrementally expanding and heat setting the tubular member, and heat setting the tube at its final diameter.

Although the figures below illustrate stents with a particular number of segments, the number of segments may vary depending on the type of interventional procedure and the desired length of the stent.

The stents of the present disclosure may have particular application in an iliofemoral vein of a patient. However, the stents may be used in any suitable location of the vasculature or other body lumen.

FIG. 1Ais a perspective view of an example stent in an expanded condition.FIG. 1Bis a plan view of a portion of the stent ofFIG. 1Aunrolled, laid flat, and in an unexpanded condition.FIG. 1Cis a plan view of a portion of the stent ofFIG. 1Aunrolled, laid flat, and in an expanded condition. In the example shown inFIGS. 1A-1C, the stent comprises a stent body100defining a longitudinal axis “k,” a proximal end102a, and a distal end102b. The stent body100may be expandable from a compressed configuration, as shown inFIG. 1B, to an expanded configuration, as shown inFIGS. 1A and 1C.

In a compressed configuration, the stent body100may define a smaller profile (e.g., a smaller outer perimeter in a cross-section taken perpendicular to longitudinal axis “k”, which may be an outer diameter in examples in which the stent body100is round in cross-section). The stent body100may be compressed for, example, before deployment at a treatment site, including when the stent body100is being delivered to the treatment site. The compressed configuration of the stent body100may allow for a lower profile delivery system, due at least in part to the smaller profile stent body100, which may increase the ease with which the stent body100may be delivered to a treatment site within a body lumen.

In some examples, the stent body100may be biased to an expanded configuration but may be compressed and constrained, for example, by a sheath of a delivery catheter until deployment of the stent body100from the delivery catheter. For example, the stent body100may formed from a shape memory material, such as, but not limited to, a nickel titanium alloy. The stent body100may be deployed at a treatment site by, for example, retraction of the sheath of the delivery catheter which may allow for the stent body100to expand into the body lumen. In some examples, the stent body100may not be biased to an expanded configuration and may be expanded at the delivery site by, for example, a balloon catheter or another mechanism suitable for expanding the stent body100from the compressed configuration to the expanded configuration. For example, the stent body100may be formed from stainless steel or another suitable non-self-expanding material.

The stent body100may include a plurality of stent segments104a-104g(collectively referred to herein as “stent segments104”). Each of the stent segments104may be defined by a pair of adjacent circumferential rows of struts, where each row of struts extends in a circumferential direction. Adjacent stent segments, such as stent segments104aand104b, may share a common row of struts. Example struts are shown as struts105a-105oinFIG. 1C, and the struts of the stent body100may be collectively referred to as struts105. Each of the struts105may be a substantially straight portion (e.g., a straight or nearly straight member) of the stent body100that may join with one or more other struts at a vertex108. For example, the strut105bis a substantially strait portion of the stent body100that joins with the struts105a,105i, and105jat the vertex108oand joins with the strut105cat the vertex108d. As another example, the strut105cis a straight portion of the stent body100that joins with the strut105bat the vertex108dand joins with the strut105dat the vertex108p. In some examples, the struts105may each remain substantially straight before and after expansion of the stent body100. However, the struts105may move relative to each other, e.g., pivoting at the vertices relative to adjacent struts, when the stent body100expands from the compressed configuration to the expanded configuration.

Although the stent body100is illustrated inFIG. 1Aas including the seven overlapping stent segments104a-104gand four independent, non-overlapping stent segments104a,104c,104e, and104g), in the other examples, the stent body100may include any suitable number of stent segments104according to particular needs. For example, in applications requiring a shorter stent, the stent body100may include a smaller number of stent segments104, such as three, four, or five stent segments. As another example, in applications requiring a longer stent, the stent body100may include a larger number of stent segments104. In some examples, each of the stent segments104may be shorter and/or longer such that a greater or fewer number of total stent segments104may result in a stent body100with the same length.

The stent segments104of the stent body100include an end segment104alocated at the proximal end102aof the stent body100and an end segment104gat the distal end102bof the stent body100. Each of the end segments104aand104gmay be located at an end of the stent body100so that it is only adjacent one other stent segment. The stent segments104further include at least one intermediate segment104b-104fdisposed between the end segment104aand the end segment104g.

The struts of each of the stent segments104may define a plurality of cells106, which may each be a closed cell defined by surrounding struts and each defining a single opening. For example, the end segment104amay define the cells106a-106d, the intermediate segment104bmay define the cells106e-106g, and the end segment104gmay define the cells106t-106w. In some examples, each of the cells106a-106dof the end segment104amay be substantially equal in size. In addition, in some examples, each of the cells106e-106gof the intermediate segment104bmay be substantially equal in size. In some examples, each of the cells106t-106wof the end segment104gmay be substantially equal in size. For example, in some examples, each of the cells106a-106d,106t-106wof the end segments104a,104g, alone or in combination with each of the cells of the intermediate segments, may be substantially equal in size.

In some examples, the terminal ends110a-110fare configured to help retain the stent body100on a delivery device (e.g., configured to mate with structures on a delivery device). In addition, in some examples, one or more terminal ends110a-110fmay be radiopaque or may include radiopaque elements, which may be configured to aid a clinician in visualizing the position of the stent body100within a body lumen.

The struts105of end segment104aare configured to define a plurality of peaks and valleys. A peak may be a vertex108that, together with the adjacent struts105forming the vertex, points in a distal or proximal direction away from a longitudinal center of the stent segment comprising the cell. For example, the struts105band105cjoin at the vertex108dto form a peak pointing in a proximal direction away from a longitudinal center of the stent segment104a. The longitudinal center of the stent segment104ais shown by the line labeled “1” inFIG. 1C. As another example, the struts105jand105kjoin at the vertex108ppto form a peak pointing in a distal direction away from the longitudinal center of the stent segment104a. A valley may be a vertex that, together with the adjacent struts forming the vertex, points in a distal or proximal direction toward the longitudinal center of the stent segment comprising the cell. For example, the struts105cand105djoin at the vertex108pto form a valley pointing in a distal direction toward the longitudinal center of the stent segment104a. As another example, the struts105kand105ljoin at the vertex108ddto form a valley pointing in a proximal direction toward the longitudinal center of the stent segment104a. In some cases, the vertex of a valley may be located at the longitudinal center of the stent segment comprising the cell. For example, the struts105a,105b,105i, and105jjoin at the vertex108oat the longitudinal center of the stent segment104a, the struts105aand105bform at valley pointing in a distal direction, and the struts105iand105jform a valley pointing in a proximal direction.

The vertices108a-108land108mm-108xxmay correspond to a plurality of peaks defined by the end segment104aand the vertices108m-108x,108aa,108bb,108o,108dd,108ee,108r,108gg,108hh,108u,108j,108kk, and108xmay correspond to a plurality of valleys defined by the end segment104a. In some examples, the intermediate segment104bmay define a plurality of peaks and valleys. For example, the vertices108aa,108bb,108o,108dd,108ee,108r,108gg,108hh,108u,108jj,108kk,108xand108mmm-108xxxmay correspond to a plurality of peaks defined by the intermediate segment104band the vertices108mm-108xx,108aaa,108nn,108ccc-108eee,108rr,108ggg-108iii,108vv,108kkk, and108lllmay correspond to a plurality of valleys defined by the intermediate segment104b.

In some examples, at least one of the end segment104aor the end segment104g(e.g., one of the end segments104aor104g, or both of the end segments104aand104g) may define more cells than at least one of the intermediate segments104b-104f. For example, the intermediate segment104band/or any of the intermediate segments104c-104f, may define x number of cells and the end segment104a, the end segment104g, or both of the end segments104a,104gmay define at least x+1 number of cells. As an example, in the illustrated example, the intermediate segment104bdefines the three cells106e,106f, and106g, the end segment104adefines four cells106a,106b,106c, and106d, and the end segment105gdefines the four cells106t,106u,106v, and106w.

In some examples, each of the stent segments104a-104gmay define the same number of peaks and valleys. For example, in the illustrated example, each of the stent segments104a-104gdefines 24 peaks and 24 valleys. For example, the end segment104adefines 24 peaks, each corresponding to one of the vertices108a-108land108mm-108xx, and defines 24 valleys, each corresponding to one of the vertices108m-108x,108aa,108bb,108o,108dd,108ee,108r,108gg,108hh,108u,108j,108kk, and108x; and the intermediate segment104bdefines 24 peaks, each corresponding to one of the vertices108aa,108bb,108o,108dd,108ee,108r,108gg,108hh,108u,108j,108kk,108xand108mmm-108xxx, and defines 24 valleys, each corresponding to one of the vertices108mm-108xx,108aaa,108nn,108ccc,108ddd,108eee,108rr,108ggg,108hhh,108iii,108w,108kkk, and108lll.

In some examples, larger cells may be defined by more surrounding struts than smaller cells and may define more peaks and valleys than smaller cells. For example, each of the cells106a,106b,106c, and106dmay be defined by twelve surrounding struts and each of the cells106e,106f, and106gmay be defined by sixteen surrounding struts. For example, the cell106bmay be defined by the twelve surrounding struts105b,105c,105d,105e,105f,105g,105j,105k,105l,105m, and105n. Also for example, each of two opposing sides of each of the cells106a,106b,106c, and106dmay define three peaks, two valleys, and two half-valleys and each of two opposing sides of each of the cells106e,106f, and106gmay define four peaks, three valleys, and two half-valleys. For example, each of two opposing sides of the cell106amay define three peaks, formed at the vertex108dbetween the struts105band105c, the vertex108ebetween the struts105dand105e, and at the vertex108fbetween the struts105fand105gon one side and formed by the vertex108ppbetween the struts105jand105k, by the vertex108qqbetween the struts105land105m, and by the vertex108rrbetween the struts105nand105oon the other side, two valleys, formed at the vertex108pbetween the struts105cand105dand at the vertex108qbetween the struts105eand105fon one side and formed by the vertex108ddbetween the struts105kand105land at the vertex108eebetween the struts105mand105non the other side, and two half valleys, formed by the struts105band105fon one side and by the struts105jand105non the other side. A half-valley may be one half of a valley, as defined by one strut defining the cell, and may combine with another half-valley, as defined by an adjacent strut defining an adjacent cell, to form the valley. For example, the strut105bmay define one half of a valley and the strut105amay define one half valley, such that the two half-valleys may join at the vertex108oto form a whole valley.

In other words, a portion of the end segment104adefining only one cell defines only three peaks, only two valleys, and only two half-valleys on each of two opposing sides of the portion of end segment104a(i.e., each circumferential row of struts defining either side of the respective stent segment). For example, the portion of the end segment104adefining the cell106amay define three peaks, corresponding to the vertices108d,108e, and108f, two valleys, corresponding to the vertices108pand108q, and two half-valleys, corresponding to the vertices108oand108r, on one side and may define three peaks, corresponding to the vertices108pp,108qq, and108rr, two valleys, corresponding to the vertices108ddand108ee, and two half-valleys, corresponding to the vertices108ccand108ff, on the other side.

In some examples, a portion of the intermediate segment104vdefining only one cell defines only four peaks, only three valleys, and only two half valleys, on each of two opposing sides of the portion of the intermediate segment. For example, the portion of the intermediate segment104bdefining the cell106emay define four peaks, corresponding to the vertices108bb,108cc,108dd, and108ee, three valleys, corresponding to the vertices108oo,108ppand108qq, and two half-valleys, corresponding to the vertices108nnand108rr, on one side and may define four peaks, corresponding to the vertices108nnn,108ooo,108ppp, and10qqq, three valleys, corresponding to the vertices108ccc,108ddd, and108eee, and two half-valleys, corresponding to the vertices108bbband108fff, on the other side.

In some examples, a portion of the end segment106gdefining only one cell defines only three peaks, only two valleys, and only two half valleys, on each of two opposing sides of the portion of the end segment104g.

The end segments of stent bodies described herein, including the stent body100shown inFIGS. 1A-1C, may have different performance requirements than the middle of the stent. For example, the configuration of the end segments may help improve the ease of deployment of the stent in a body lumen of a patient and/or deployment accuracy. For example, although a greater number of cells and smaller cells in the end segments may decrease flexibility of the end segments, they may help increase the ease of deployment and/or deployment accuracy of the stent in a body lumen.

The pattern of the cells106of the end segments104aand104gof the stent body100as described herein, which have a different configuration than the intermediate segments of the stent body100, including a greater number of cells than the intermediate segments and smaller cells than the cells of the intermediate segments (i.e. cells surrounded by fewer struts and including fewer peaks and valleys than the cells of the intermediate segments), may improve ease of deployment and/or deployment accuracy compared to stents with the same configuration in the end and intermediate segments. For example, the stent may be deployed more smoothly (e.g., may experience less “jump”) from a delivery device, such that the stent may be more easily, predictably, and accurately deployed in an intended site in a body lumen of a patient without the stent jumping out of the delivery device and away from the intended target site.

The pattern of the cells106of the end segments104aand104gof the stent body100as described herein may also accomplish particular technical advantages compared to stents with end segments including the same number of struts but twice the number of evenly sized cells as intermediate segments. For example, the end segments104aand104gmay have increased flexibility over such designs without a substantial reduction in radial force or lateral force. With increased flexibility in the end segments104aand104g, overlapped stents may have smoother flexibility transitions in a region of overlap and, therefore, improved durability in an overlapped configuration.

FIG. 2is a flow diagram illustrating an example method of manufacture of the stents shown inFIGS. 1A-1C. In accordance this process of manufacture, a tube, such as a nitinol tube having an appropriate defined diameter is selected (202). For a venous application, the stent may require a greater wall thickness relative to arterial stents, e.g., approximately 0.45 mm for the 10, 12 and 14 mm stents and approximately 0.7 mm for the 16, 18 and 20 mm stents. The tube is then positioned with respect to a laser. The laser, which is programmed to provide the stent segment pattern of the stent body100described hereinabove, is activated to form the stent segment pattern (204).

In examples in which the stent is self-expandable and, therefore, formed from a self-expanding material, the cut tube is then subjected to a shape-setting process in which the cut tube is expanded on a mandrel and then heated (206). Multiple incremental expansions and heating cycles may be used to shape-set the stent body100to a desired expanded diameter (208). In some examples, the final expanded diameter may be equal to the desired deployed diameter of the stent body100. The stent body100may be axially restrained such that the length of stent does not change during expansion.

FIG. 3is a flow diagram illustrating an example method of implanting the stents shown inFIGS. 1A-1C. A guide member may be introduced into a body lumen of a patient (302). The guide member may be advanced though the body lumen to position a leading end (distal end) of the guide member at a target location as determined by a clinician. In some examples, the guide member may include a guidewire, a guide catheter, or both a guidewire and a guide catheter.

An outer catheter may be introduced over the guide member, or, in some examples, within the guide member, and a distal portion of the outer catheter may be advanced substantially adjacent to the treatment site as determined by the clinician (304). The outer catheter may define an outer catheter lumen.

The guide member may be retracted to remove the guide member from the outer catheter lumen (306), while leaving the outer catheter in place.

In some examples, an inner catheter may be introduced within the outer catheter and a distal portion of the inner catheter may be advanced proximate to the treatment site (308). In some examples, the distal portion of an inner catheter may be advanced to be substantially aligned with the distal portion of the outer catheter. In such examples, a distal portion of the inner catheter may be secured to a stent, including the stent body100ofFIGS. 1A-1C.

In some examples, both the outer catheter and inner catheter may be advanced to the target location simultaneously, with the inner catheter being inside the outer catheter and the stent being positioned between the inner catheter and the outer catheter. For example, the delivery device described in U.S. patent application Ser. No. 14/256,136 naming inventors Senness et al., which is entitled, “STENT DELIVERY SYSTEM” and is incorporated herein by reference in its entirety, may be used to deliver any of the stents described herein. In such examples, the outer catheter may help retain the stent relative to the inner catheter.

The stent may be released from the inner catheter lumen and to the treatment site (310). For example, in some examples, a plunger may be advanced within the inner catheter lumen to push the stent from a distal portion of the inner catheter lumen. A clinician may control the plunger to advance the plunger such that the stent is advanced from the inner catheter.

In other examples, the stent may be positioned between the inner and outer catheters, and the outer catheter may be retracted with respect to the inner catheter and stent to allow for release of the stent from the inner catheter.

As the stent is released from a distal end of the inner catheter lumen or from around an outer surface of the inner catheter, the stent may expand such that it is secured against the wall of the body lumen and anchors the stent within the body lumen. In other examples, the stent may be expanded via a balloon or other mechanism.

After satisfactory delivery of the stent, other elements, including, for example, the outer catheter, an inner catheter, and/or a plunger may be removed from the body lumen (312).