JP6937240B2 - Stent graft - Google Patents

Description

The present invention relates to the improvement of stents and stent grafts used for diseases such as aneurysms.
More specifically, in the present invention, in order to treat a dilated disease (aneurysm or the like) and an arterial stenotic disease or other disease, a stent graft used for treating the aneurysm or the like is placed at a safe site of the affected area. Regarding stent grafts used as artificial blood vessels

The aortic arch is the part of the ascending aorta that exits the left ventricle and is curved in an arch shape that connects to the descending aorta. It is said that there is a bend (three-dimensional bending). In Patent Document 1, in order to deal with the steep bending, the applicant applies to a stent having a pre-bent form formed by connecting annular units and a tubular member made of synthetic resin (referred to as a graft) on the outer periphery of the stent. Disclosed the invention of a stent graft coated with. As shown in FIG. 7, the stent graft is preferably placed in the aorta including the aneurysm 8 as an artificial blood vessel to prevent the aneurysm from rupturing.

The stent graft (referred to as "101SG") was basically prepared to be suitable for these three-dimensional flexions, but the steeply flexed portion of the aortic arch is shown in FIG. 7 (B). As described above, it was sometimes difficult to place the aortic arch in close contact with the lesser curvature side (inside the aortic arch with a small diameter).

For this reason, a gap (called a bird beak) SBV was formed between the lesser curvature side and the indwelling stent graft.
In this case, when blood flows into the aortic arch from the downstream side (ascending aorta), it enters the gap SBV where blood (blood flow F') is generated as shown in FIG. 7, and the terminal DE side of the stent graft is indicated by G. In some cases, it may cause problems such as pushing up, moving the stent graft, stent fatigue / breakage, internal leakage (end leak), and the like.

Patent Document 2 and Patent Document 3 disclose an invention that makes it possible to avoid such a phenomenon by a stent graft indwelling device system. (Hereinafter, the reference numerals described in the patent documents are described as they are with <>, and the names of each member are quoted as they are.) That is,
Patent Document 2 describes an invention of a system for implanting a stent graft (prosthesis) by making full use of a peculiar form of bow-shaped control lumen <12> and support wires <22, 23>.
Patent Document 3 describes an invention including the following stent graft, a locking member, and one or more diameter reducing members as a supply system. That is,
Stent grafts include tubular grafts that include first and second longitudinally extending sides that are placed opposite to each other and tangentially connected.
When the locking member is in the locking position, the locking member constrains the surface of the graft to the cannula. The first diameter reducing member is slidably connected to the first portion of the graft located close to the tangent and slidable to the second portion of the graft separated from the tangent in the circumferential direction. Is connected to.
When the first diameter-reducing member is in the restraint position, the second portion of the graft is pulled towards the first portion of the graft and the proximal portion of the stent graft has a diameter-reducing structure with at least two lobes.

Patent Document 4 describes the affected area by aligning the long side of the implant body <20> with the lateral curvature of the long aortic arch and aligning the short side of the implant body with the short medial curvature of the aortic arch. When deployed in, the prosthesis <10> is facilitated to match the shape of the anatomical structure of the aortic arch, allowing accurate and accurate placement of the prosthesis <10> in the meandering aortic arch. Discloses the invention to be used.
That is, the distance between the first proximal stent <30a> and the second proximal stent <30b> varies along the outer circumference of the implant body <20>. For example, the longitudinal length of the top of the prosthesis is formed longer than, for example, the longitudinal length of the bottom of the prosthesis to form an inclined end. The distance between the first proximal stent <30a> and the second proximal stent <30b> along the longitudinal length of the apex is the first along the longitudinal length of the bottom. It is formed larger than the distance between the proximal stent and the second proximal stent.

Patent No. 4064724 (Claims, FIGS. 1 to 4) Patent No. 5688216 (Claims, FIGS. 5-1 to 5-3) Japanese Unexamined Patent Publication No. 2012-139500 (summary column, FIG. 1) Japanese Unexamined Patent Publication No. 2013-71005 ([0047], [089], FIG. 6, FIG. 8, FIG. 10, FIG. 12, FIG. 14)

The prior invention described in Patent Document 1 to Patent Document 4 described above has the following problems, and it is difficult to accurately deal with the steep bending (three-dimensional bending). That is,
As described in Patent Document 1, only the form of the stent skeleton that has been bent in advance and the stent graft that is completely covered with the graft has a limit in adhering to the lesser curvature side of the aortic arch and filling the gap SBV. be.
Since Patent Document 2 and Patent Document 3 are inventions of a system for implanting a stent graft (prosthesis) by organically binding each member having a peculiar form, it is difficult for an operator to acquire the procedure for carrying out the system. Issues such as are pointed out.
In Patent Document 4, since the struts constituting the stent have the same length and are all covered with a graft, it is difficult to bring them into close contact with the lesser curvature side of the aortic arch, which is sharply bent at the terminal side.

Therefore, the present inventor has reached the following invention as a result of repeated studies in order to solve the above problems.
The present invention includes a stent which is indwelled in the curved portion of blood vessel, Ru stent graft der and a graft covering the stent.
The stent is
It has a tubular body that extends in the longitudinal direction and expands in the circumferential direction.
The tubular body has a plurality of annular units connected in the longitudinal direction and has a plurality of annular units.
The annular unit is formed in a substantially zigzag shape continuously in the circumferential direction by alternately connecting a plurality of side peaks in one direction and valleys in the other direction.
Of the plurality of tubular units, the terminal-side annular unit arranged on the terminal side has a plurality of struts having different lengths.
Wherein the plurality of struts, viewed contains a long first strut which is disposed corresponding to the outer portion of the curved portion, and a shortest second strut which is disposed corresponding to the inner portion of the curved portion,
The terminal end of the second strut is offset from the terminal end of the first strut to the opposite side of the terminal in the longitudinal direction.
The graft is
The longitudinal dimension of the second covering portion that covers the second strut with respect to the first covering portion that is arranged to correspond to the shape of the terminal side portion of the terminal side annular unit and covers the first strut. Is shortened.

According to the stent graft of the present invention, it is arranged so as to correspond to the shortest second strut distal annular unit in the inner portion of the curved portion, for example, to easily fit into small弯側was steeply bent aortic arch be able to. This makes it possible to suitably eliminate problems such as movement of the stent graft after placement of the affected area, stent fatigue / breakage, and internal leakage (end leak).

FIG. 1 is an overall view (front view / schematic view) of the stent 1 of the present invention 1 (Type (I)). FIG. 2 is a partially enlarged view of the vicinity of the terminal annular unit 4DE of the stent 1 (expanded view of the distal annular unit 4DE at the time of assembly / placement of the affected portion expanded in the circumferential CR direction by τ = 360 °). (Here, τ is a polar coordinate display with the center of the front surface (circular opening) of the annular unit as the origin (the position around the annular unit) when the terminal annular unit is assembled from the developed view. Indicates the declination τ when. The same shall apply hereinafter.) FIG. 3 is a partially enlarged view of the vicinity of the terminal annular unit 4DE of the stent 1 (expanded view of the distal annular unit 4DE at the time of assembly / placement of the affected portion expanded in the circumferential CR direction by τ = 360 °). 4 (A) and 4 (B) are schematic views of the stent graft 1SG of the present invention placed in the affected area, and (B) is a partially enlarged view of (A). FIG. 5 is an overall view (front view / schematic view) of the stent graft 11SG of the present invention 2 (Type (II)). FIG. 6 is a schematic view of the stent graft 11SG of the present invention placed in the affected area. 7 (A) and 7 (B) are schematic views of a conventional stent graft 101SG placed in the affected area, and (B) is a partially enlarged view of (A).

Hereinafter, the present invention will be described in detail with reference to the drawings.
Hereinafter, in order to clearly explain the present invention, the following definitions will be made with reference to the arrangement shown in FIG. In FIG. 1, in order to avoid complication of the description of each line, the struts 4ST and 5ST are shown so as to overlap when viewed from the front direction to the back direction. The same applies to FIG.
(Definition 1) As shown in FIG. 1, the “first side portion S1 side” means the front side of the paper surface and the front direction of the stent. Hereinafter, "... side" may be described as "... direction".
(Definition 2) As shown in FIG. 1, the “second side portion S2 side” means the back side of the paper surface and the back side direction of the stent.
(Definition 3) As shown in FIG. 1, the “terminal DE side” means the left side of the paper.
(Definition 4) As shown in FIG. 1, the “base end PE side” means the right side of the paper.
(Definition 5) As shown in FIG. 1, the “third side portion S3 side” means the upper side of the paper surface. In the aortic arch, it corresponds to the greater curvature side.
(Definition 6) As shown in FIG. 1, the “fourth side portion S4 side” means the lower side of the paper surface. In the aortic arch, it corresponds to the lesser curvature side.

(Definition 7) “Longitudinal L direction” means the longitudinal direction of the stent as shown in FIG.
(Definition 8) The “circumferential CR direction” means a direction extending from the center C in the longitudinal L direction of the stent to the “side S side”, and is also referred to as the “side S direction”.
The side S direction includes the first side S1 side, the second side S2 side, the third side S3 side, the fourth side S4 side, and all the directions between them.
A part of the above circumferential CR (side S) direction may be described as "one direction of the side portion", and the side opposite to the "one direction of the side portion" may be described as "one direction of the other side portion". be.
For example, the third side portion S3 side may be described as one direction of the side portion, and the opposite side of the fourth side portion S4 side may be described as one direction of the other side portion.
Further, a code indicating a direction such as S3 may be described next to the code of each part.
For example, 4STS3 means a strut 4ST on the third side.

(Definition 10)
The "strut" is also referred to as a strut, and is a substantially linear linear or wire-shaped member forming the "annular unit 4" and the "connecting unit 5".
The substantially linear "struts" constituting the "annular unit 4" may be referred to as "annular struts 4ST" in the sense of "struts constituting the annular unit", or may be simply referred to as "struts 4ST". ..
Further, the member constituting the "connecting unit 5" may be described as "connecting strut 5ST" or simply "strut 5ST".

[Circular unit 4]
As shown in FIG. 1, the stent 1 of the present invention has a so-called substantially tubular shape formed by connecting an annular unit 4 with a connecting unit 5.
For example, referring to FIG. 1, the annular unit 4 is formed of a substantially zigzag pattern as described in detail below, and the folding point of the zigzag pattern is a bent portion. The annular unit configured in this way has such a bent portion 4C on the terminal DE side and the base end PE side. Hereinafter, the bent portion 4C on the terminal DE side is referred to as a “mountain portion M” and the base end. The bent portion 4C on the PE side is referred to as "valley portion V".
The "mountain part M" and the "valley part V" in the circumferential CR direction are connected by a so-called "substantially linear strut 4ST".

There is a predetermined space SP between the mountain part M and the mountain part M, and between the valley part V and the valley part V.
The annular unit 4 is a member in which a plurality of substantially linear struts 4ST are continuously formed (arranged) in a so-called "substantially zigzag shape" as described above in the circumferential CR direction. This zigzag arrangement is also referred to as a "substantially zigzag pattern" or a "substantially wavy pattern". The peaks M and valleys V are alternately formed by this zigzag pattern. As described above, the mountain portion M and the valley portion V form the mountain portion bending portion M (4C) and the valley portion bending portion V (4C), respectively. (As described above, the mountain portion is the bent portion on the terminal DE side, and the valley portion is the bent portion on the base end PE side.)

The connecting unit 5 is, for example, a member that connects the nth row (4n), the n + 1th row (4n + 1), and two "annular units 4". It is composed of a plurality of so-called substantially linear (usually about 2-4) connected struts 5ST (two in the example of FIG. 1).
In FIG. 1, the annular unit 4 is composed of five units: the nth row (4n), the n + 1st row (4n + 1), the n + 2nd row (4n + 2), the n + 3rd row (4n + 3), and the n + 4th row (4n + 4). Will be done.

[Hook 6 etc.]
As shown in FIG. 1-3, the stent 1 has a hook 6 arranged at one end in the circumferential CR (side S) direction on the terminal DE side of the annular unit 4DE on the terminal side of the stent 1. Is preferable.
The hook 6 is arranged so that the base end PE side is shifted from the third side portion S3 to the left side of the first side portion S1 / paper surface at a predetermined angle (varies depending on the specifications of each stent skeleton). The hook 6 is a site where the stent or the stent graft is pulled to the indwelling position by locking it to the tip tip leading to the indwelling position.
The contrast marker MK is preferably arranged at predetermined positions of the mountain portion M and the valley portion V so that the positions of the openings of the hook 6 and the graft GF can be easily confirmed. (See Patent No. 4298244)
Further, in order to improve the adhesion to the blood vessel wall, a fin FN (also referred to as an extension member) is attached to the valley portion V of the terminal side annular unit 4DE, and the longitudinal L in the direction of the adjacent proximal end PE side annular unit 4n + 1. It is also a preferable aspect that the extension is extended along the direction. (See Japanese Patent Application Laid-Open No. 2008-99995, International Publication WO2009-118912)

[Strut 4ST (tilt cut structure) of the annular unit 4DE on the terminal DE side]
What is characteristic of the present invention 1 is that the terminal annular unit 4DE is declined in the circumferential CR direction in FIGS. 2 and 3 (a partially enlarged view of the vicinity of the terminal annular unit 4DE of the stent 1, during assembly / placement of the affected area). As shown in the developed view obtained by expanding the angle τ = 360 °), the length of the stent 4ST is inclined. That is, with respect to the strut 4STS3 (of normal length) in one direction (third side portion S3) of the side portion S (corresponding to the bay side from the definition 5), τ = 180 in the circumferential CR direction. The strut 4STS4 in one direction (fourth side S4 / leftmost and rightmost of the paper surface) (corresponding to the small bay side from definition 6) of the other side S (rotated by °) has a short length of 4STL. (As will be described below, this is referred to as the "tilted cut structure" or simply the "tilted structure"). In this respect, the conventional stent is very different from the present invention in that all 4DE struts 4ST are configured to have the same length.

This point will be described in more detail.
In the present invention, the "length of strut 4ST" (= 4STL) means the longitudinal direction (L) of Y, where Y is the physical length measured along the strut from the peak M to the valley V. It means the component Y (L). That is, as shown in FIG. 2, 4STL is defined as the distance in the longitudinal L (terminal DE-base end PE) direction from the mountain portion M to the valley portion V of the strut 4ST.

Assuming that the length 4STL (4STLL / maximum length) of the strut 4STS3 in one direction (third side portion S3) of the side portion S (corresponding to the bay side) is 100, (τ = 180 in the circumferential CR direction). Length of strut 4STS4 in one direction (fourth side S4 / leftmost and rightmost of the paper) (corresponding to the small bay side) of the other side S (rotated by °) 4STL (4STLS / minimum length) 2 shows an example formed at about 80, and FIG. 3 shows an example formed at about 53.
(As will be described later, if the inclined cut rate φ is defined by φ = [(4STLS / 4STLL) × 100%], the inclined cut rate φ = 80% (FIG. 2) and φ = 53 (FIG. 3).)

In addition, in FIG. 2 and FIG. 3, in order to illustrate the dimension of the length 4STL of each strut 4ST, an example of the specific dimension of the maximum length 4STLL is described. Furthermore, in order to make it easier to understand the specific dimensions of the minimum length 4STLS and the intermediate length 4STLM, in the development view of FIG. The dimensions up to the extension line DEL on the terminal DE side (connecting a plurality of mountain portions M having a maximum length of 4 STLL) are described. (Note that the DEL is also an extension line of the end face forming the end corresponding to 4STLL of the terminal side annular member (4DE).)

2 and 3 show a rotation (argument τ = 90 ° in the circumferential CR direction) with respect to a length 4STL (4STLL) of a plurality of struts 4STS3 near one direction of the side portion S (third side portion S3). The length 4STL (4STLM / intermediate length) of each strut 4ST in one direction of the side portion S in the middle (first side portion S1 / left side of the paper surface, second side portion S2 / right side of the paper surface) is shortened. In addition, the length 4STL (4STLS) of the strut 4STS4 in one direction (fourth side portion S4 / leftmost and rightmost of the paper surface) of the other side portion S (rotated by τ = 180 ° in the circumferential CR direction) is the most. It is formed short.
Assuming that the length (maximum length) 4STL of the strut 4STS3 in one direction (third side portion S3) of the side portion S is 100, one of the side portions S in the middle (rotated by τ = 90 ° in the circumferential CR direction). The length 4STL (4STLM) of each strut 4ST in the direction (first side portion S1 / left side of the paper surface, second side portion S2 / right side of the paper surface) is approximately 90 (φ = 90%) in FIG. , Approximately 85 (φ = 85%) and approximately 70 (φ = 70%) are shown.

The length 4STL of the strut 4ST is rotated from one direction of the side S (third side S3) to one direction of the other side S (rotated by a deviation angle τ = 180 ° in the circumferential CR direction) (fourth side). 100, 92 (φ = 92%), 80 (φ = 80%) in FIG. 2, 100, 84 (φ = 84%) in FIG. 3, toward S4 / leftmost and rightmost sides of the paper. Examples of stepwise shortening such as 69 (φ = 69%) and 53 (φ = 53%) are shown.
In other words, the strut 4ST is "rotated by τ = 180 °" from one direction of the side S (third side S3) (Owan side) and one direction of the other side S (fourth side S4 / It has a so-called inclined cut structure in which it is cut so as to be inclined toward the leftmost and rightmost sides of the paper (small bay side).

In the present invention, the basic reason why the stent has such an inclined cut structure is that the one side portion S3 of the stent is a portion in contact with a large bay portion having a long distance but a gentle degree of curvature, while the deviation angle from now on. Considering that the other side S4 on the side rotated by τ = 180 ° is in contact with the small bay, which is a short distance but has a steep bend, this large bay is closer to a sufficiently long stent. It is essential to maintain good contact for a long distance, while for the small bay, a short length stent should be used to cope with the short but steep bends and bring them into close contact. For this reason, by adopting an inclined cut structure for both, the two are smoothly connected while maintaining close contact from the large bay to the small bay including a steep bend.

The tilt cut ratio φ [ = (4STLS / 4STLL) × 100%] is φ = approximately 80% in FIG. 2 and φ = approximately 53% in FIG. 3 as described above.

[Construction of stent graft]
In the present invention, the outer circumference of the stent 1 formed as described above (excluding the openings on the terminal DE side and the proximal PE side. The openings are the entrances of blood flow when the stent is placed in the blood vessel as shown in the figure. The outlet is formed) is coated with a tubular member (graft GF) made of synthetic resin to obtain a stent graphft 1SG. (See Fig. 4)
The end-side annular unit 4DE has the inclined cut structure [one direction of the side portion S (third side portion S3) and one direction of the other side portion S (in the direction rotated by 180 ° declination τ = 180 °). It is inclined toward the 4 side portion S4). ], It is coated with graft GF. That is, as shown in FIG. 4, the graft also has an inclined structure corresponding to the inclined structure of the stent.

[effect]
As described above, the stent 1 of the present invention has a slanted cut structure on the terminal DE side of the terminal annular unit 4DE as described above, and has a strut 4ST length 4ST (4STLS) on the fourth side S4 (lesser curvature side). ) Is formed to the minimum, so that when it is placed in the aortic arch as shown in FIG. 4, it becomes easy to adhere to the lesser curvature side. As a result, unlike the conventional stent of FIG. 7, the gap (bird beak) SBV formed between the stent 1 and the lesser curvature side is eliminated, and the blood flow from the downstream side is quickly brought into the inside of the stent 1. Can be distributed. Therefore, unlike the conventional case, blood flow does not enter the SBV and cause problems such as movement of the stent graft, fatigue, and internal leakage.

In the present invention, as described above, in the terminal annular unit 4DE, the strut 4ST length 4STL has a maximum length 4STLL, a minimum length 4STLS, and an intermediate length 4STLM thereof. ..
Inclined cut with 4STLL>4STLM> 4STLS from one direction of the side S (third side S3) to one direction of the other side S (rotated by τ = 180 °) (fourth side S4). Forming a structure.
The inclined cut ratio φ [= (4STLS / 4STLL) × 100%] is formed to be φ = 30% to 90%, preferably φ = 40% to 85%, and more preferably φ = 50% to 80%.
If the inclination cut ratio φ is too large, for example, exceeding 90%, the length of the strut that should be in close contact with the lesser curvature side is almost the same as the length of the strut on the lesser curvature side due to the above reason, so that the strut bends sharply. On the other hand, if the diameter of the blood vessel is too small, such as less than 30, the strut 4ST is too small and only the strut of a small length is formed, and this part cannot form a sufficient annulus. Therefore, it becomes difficult to coat the stent 1 (the terminal annular unit) with the graft GF.

[Inclination angle θ]
In the present invention, the inclination angle θ is defined as follows. That is, the extension line DEL on the terminal DE side connecting the mountain parts M of the terminal side annular unit 4DE, the apex of the maximum length 4STLL (mountain part M), and the apex of the minimum length 4STLS (mountain part M). It is defined by the angle θ at which the connected extension lines MLS (or “inclined lines”) intersect. (Or, it is defined by the angle θ at which the MLS and the line connecting a plurality of vertices (mountains) of a constant height 4STLL (reference line GL (referred to as (Ground line))) intersect.)
The inclination angle θ is formed to be θ = 5 ° to 30 °, preferably θ = 8 ° to 20 °, and more preferably θ = 10 ° to 15 °.
If the inclination angle θ is too small, for example, less than 5 °, it is difficult for a steeply bent blood vessel to adhere to the lesser curvature side, while if θ is too large, for example, more than 30 °, it is near the lesser curvature side. The strut 4ST (particularly 4STLS) is too small to coat the stent 1 with graft GF.

[Other stent grafts (Type (II) stents and stent grafts]
Next, Invention 2 will be described.
Invention 2 is based on essentially the same technical idea as Invention 1, and has the same effect as Invention 1 (adhesion of the stent graft to the steep part of the small bay), and the configuration on the graft side covering the stent (inclined cut structure). ) To be realized. That is, all the struts constituting the annular member (annular unit) of the terminal DE have a standard length (= 4STL), and the region (LL) on the bay side is covered with the graft which is the annular coating member up to the end. On the other hand, in the region (SS) on the small bay side, the graft itself has an inclined structure. This point will be described more specifically in the following paragraph [0042].

FIG. 5 shows an example of another stent graft 11SG (stent 11) according to the present invention 2. The length of the strut ST of (i) the terminal annular member 4DE is substantially the same as that of the stent 1 of FIG. (Ii) Instead, for the graft GF, which is a synthetic resin annular member, that is, the graft GF covering the stent 11, the terminal DE side is inclined in the same manner as the terminal DE side annular unit 4DE of the stent 1. The cut structure and a part of the annular unit 4DE on the terminal DE side of the (iii) stent 11 are exposed on the terminal DE side and the fourth side S4 side (small bay side) as shown in FIG. It differs in that. Although the description of the marker MK and the fin FN described in FIG. 1 is omitted in FIG. 5, these techniques are naturally applied to the stent graft 11.

The stent 11 is configured such that the terminal DE side of the graft GF side (not the stent side) has an inclined structure as described above, and the length of the fourth side portion S4 (lesser curvature side) is (most) shorter. As with the conventional stent graft 101SG proposed by the applicant, the stent graft 11SG has a gap SBV between the stent 11 (terminal annular unit 14DE) and the lesser curvature side, but is shown in FIG. As described above, since the graft GF having an inclined structure is in close contact with the steep wall surface of the lesser curvature, a substantial gap SBV is not formed between the graft GF and the graft GF in the portion. Therefore, the ascending blood flow does not push up the terminal DE side of the stent graft as shown in FIG. 7 (B) and cause the stent graft to move or the like.
Therefore, when the stent graft of the present invention is placed in the aortic arch, the graft GF easily adheres to the lesser curvature side as shown in FIG.

Since there is a wide space SP as shown in FIG. 1 between each strut 14ST of the terminal side annular unit 14DE, the blood flow F from the downstream side is partially (upper) exposed terminal DE side annular unit. It can be quickly circulated inside the stent 11 through 14DE.
The stent grafts of Patent Document 4 are all composed of struts of the same length, and for the time being, all of the end faces on the terminal DE side are apparently "inclined structure" due to the struts of the same length. (Same length as the side strut) Since the strut is completely covered with the graft, the graft is supported (reinforced) by the (long) strut all over the lesser curvature side, so that the blood vessel is sharply bent. In the case of, it is difficult to bend along the lesser curvature side and it is difficult to adhere.

More specifically, regarding the annular unit on the terminal side, on the large bay side, it is closely attached to the relatively long and gentle surface of the bend formed by the strut of the standard length, while the short distance but the sharp bend is small. On the bay side, sufficient flexibility and adhesion can be obtained only by gradually shortening the strut length toward the small bay side. According to the present inventor, it is difficult to accurately correspond a large bay with a gentle but long distance and a small bay with a short but steep bend with struts of the same length. The object of the present invention is achieved only by dividing the aortic arch into a large bay side region LL and a small bay side region SS as shown in FIG. 5 and using different struts suitable for each region. Can be done.

As shown in FIG. 5, the stent graft 11SG according to the invention 2 has a maximum length GFLL, a minimum length GFLL, and an intermediate length GFLM as the length GFL of the graft GF on the terminal DE side.
The length GFL of the stent graft is from the valley V in the longitudinal L direction (terminal DE-base PE direction) of the terminal annular unit 14DE to the portion covering the stent toward the mountain M as shown in FIG. Defined as the distance of the graft GF.
(As shown in FIG. 5, in the portion indwelled on the bay side, the graft GF of the stent graft 11SG reaches from the valley V to the mountain M (that is, covers all of the strut 14ST). The portion of the graft GF covering the strut 14ST gradually decreases toward the small bay side, that is, the portion covering the strut 14ST decreases in the order of GFLL → GFLM → GFLS, that is, decreases with a certain inclination (this inclination line). Is represented by GFC.).).

As described above, in the invention 2, one direction (fourth side portion S4) (small) of the other side portion S rotated by τ = 180 ° from one direction of the side portion S (third side portion S3) (large bay side). Toward the bay side), the graft GF is formed so as to have an inclined cut structure similar to the inclined cut structure of the stent in the invention 1 described above so that GFLL>GFLM> GFLS.
The inclined cut ratio φ ′ [= (GFLS / GFLL) × 100%] is formed to be φ ′ = 30% to 90%, preferably φ ′ = 40% to 85%, and 50% to 80%.
If φ'is too large, for example, to exceed 90, it is difficult for a steeply bent blood vessel to adhere to the lesser curvature side, while if φ'is too small, for example, less than 30, the graft GF becomes too small. This makes it difficult to coat the stent 1 with graft GF.

[Inclination angle θ']
Further, the inclination angle θ is the extension line DEL on the terminal DE side connecting the peaks M of the terminal annular unit 14DE, the cut start position (GFLL) of the graft GF of the terminal annular unit 14DE, and the cut end position (GFLS). It is defined by the angle θ'at which the extension line GFC connecting (on the DE side at the end of the strut 14ST and on the lesser curvature side) intersects.
The inclination angle θ'is formed at θ'= 5 ° to 30 °, preferably θ'= 8 ° to 20 °, and more preferably θ'= 10 ° to 15 °.
If this inclination angle θ'is too small, for example, less than 5 °, it is difficult for a steeply bent blood vessel to adhere to the lesser curvature side, while if θ'is too large, for example, it exceeds 30 °, it is cut. The length GFLS of the graft at the end position is too small, and it is difficult to coat the strut 14ST on the lesser curvature side of the distal annular unit of the stent 11 with the graft GF and bring the coated portion into close contact with the lesser curvature side. Become.

[Material of stents 1 and 11 (metal material)]
The materials forming the annular strut 4ST, annular unit 4, connecting strut 5ST, connecting unit 5, hooks 6 and 16, and fin FN constituting the stents 1 and 11 of the present invention are not particularly limited, and are made of stainless steel such as SUS316L. Steel; superelastic alloys such as Ti—Ni alloys; titanium-based alloys, Co—Cr-based alloys; preferably formed from metal wires such as Ta, Ti, W, and Au. In addition, a stent (annular unit, strut, connecting strut, hook) is made of a polymer material such as urethane, which is commonly used for stents formed from these metals, a physiologically active substance such as heparin and urokinase, and a thin film of an antithrombotic drug such as argatroban. ) Is also preferable because it can impart a function of preventing the formation of thrombi on the surface of the stent.

[Synthetic resin tubular member (graft)]
Further, the stents 1 and 11 can be used as they are, but usually, the stent graft SG (usually used as an artificial blood vessel) is preferably used as an artificial blood vessel by coating the outer surface of the stent with a graft GF which is a synthetic resin annular member as a skeleton. (See FIG. 4) can be formed. As the material for forming the graft GF, a film-like or fibrous material is preferable. For example, a film made of a fluororesin (PTFE: polytetrafluoroethylene, PFA: tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer) ( A tubular member made of synthetic resin made of single layer or two or more layers), Dacron, Mylar (registered trademark, polyethylene terephthalate) fiber, etc. is used, but the present invention is not limited to this.

[Construction of stent graft]
For example, an example of a stent graft is as follows. That is, a stent ST having a diameter of 40 mm when no load was applied (a bent stent composed of five tubular units having an annular member on the terminal DE side having an inclined cut structure as shown in FIG. 1) was 30 mm (75%). ). A tubular member (graft) made of fluororesin (PTFE) having a diameter of 31 mm can be used, and its end and an arbitrary portion can be fixed and covered with the stent while being sewn to the stent with suture to form a stent graft SG.
The stent graft thus formed is a tubular member made of synthetic resin, which has a spring action of itself, an inclined cut structure at the tip of the stent, and a flexible synthetic resin tubular member of the stents 1 and 11 made of a metal wire as a skeleton. Since it is covered and composited with (graft), it can follow the three-dimensional bending of blood vessels, especially the steep bending on the small bay side.

Since the terminal DE side of the stent (stent graft) of the present invention is formed in an inclined cut structure, it is easy to adhere to the lesser curvature side of the aortic arch that is bent sharply, and the stent or the like is placed on the inner wall of the blood vessel at the tip of the bird beak. It never floats from the surface.
Therefore, the stent (stent graft) of the present invention can suitably eliminate problems such as movement of the stent graft after placement of the affected area, stent fatigue / breakage, and internal leakage (end leak) caused by bird beak, and thus dilate the artery. As a medical device preferably used in the medical field for treating diseases such as sexual diseases (aneurysms, etc.), its industrial applicability is extremely high.

1, 11 Stents 1SG, 11SG, 101SG Stent Grafts 4, 14 Ring Units 4DE, 14DE Terminal Ring Units (Terminal Ring Members)
4ST, 14ST Circular strut 4C Flexion part M Tanibe V Mountain part 5 Connection part 5ST Connection strut 6 Hook 8 Aneurysm
MK Marker FN Fin θ Stent Tilt Angle θ'Stent Graft Tilt Angle φ Stent Tilt Cut Rate
Inclined cut rate of φ'stent graft

Claims (4)

A stent graft comprising a stent placed in a curved portion of a blood vessel and a graft covering the stent .
The stent is
It has a tubular body that extends in the longitudinal direction and expands in the circumferential direction.
The tubular body has a plurality of annular units connected in the longitudinal direction and has a plurality of annular units.
The annular unit is formed in a substantially zigzag shape continuously in the circumferential direction by alternately connecting a plurality of side peaks in one direction and valleys in the other direction.
Of the plurality of tubular units, the terminal-side annular unit arranged on the terminal side has a plurality of struts having different lengths.
Wherein the plurality of struts, viewed contains a long first strut which is disposed corresponding to the outer portion of the curved portion, and a shortest second strut which is disposed corresponding to the inner portion of the curved portion,
The terminal end of the second strut is displaced from the terminal end of the first strut to the opposite side to the terminal side in the longitudinal direction.
The graft is
The longitudinal dimension of the second covering portion that covers the second strut with respect to the first covering portion that is arranged to correspond to the shape of the terminal side portion of the terminal side annular unit and covers the first strut. stent grafts, which are shorter. The plurality of struts
Further including a third strut having a length intermediate between the first strut and the second strut.
Toward the inner portion from the outer portion of the curved portion, the first strut, the third strut, the stent graft of claim 1 comprising forming the inclined cut structure disposed in the order of the second strut .. The distance between the terminal annular unit and the tubular unit adjacent to the terminal annular unit is large so that the distance between the portions where the first struts are arranged is large and the distance between the portions where the second struts are arranged is the smallest. spaced stent graft according to claim 1 or 2 comprising. Wherein the ratio of the axial length of the second strut to axial length of the first strut, the stent graft according to any one of claim 1 to 3, which is a range of 30% to 90%.

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