In-vivo indwelling implement

Abstract

Provided is an in-vivo indwelling implement that includes a coil (2) having a longitudinal axis direction (x) and a radial direction (y), wherein: the coil (2) has a proximal-side coil (2A) constituted by winding a first wire material (31) and a distal-side coil (2B) joined to the proximal-side coil (2A) and constituted by winding a second wire material (32); the cross-sectional shape (S1) of the first wire material (31) in a plane parallel to the longitudinal axis direction (x) satisfies condition 1, and the cross-sectional shape (S2) of the second wire material (32) in a plane parallel to the longitudinal axis direction (x) satisfies condition 2. Condition 1: Wmax1 / Wave1, which is the ratio of the maximum value Wmax1 of the length (W1) in the radial direction (y) of the cross-sectional shape (S1) to the average value Wave1 of the length (W1) in the radial direction (y) of the cross-sectional shape (S1), is no more than 1.22. Condition 2: Wmax2 / Wave2, which is the ratio of the maximum value Wmax2 of the length (W2) in the radial direction (y) of the cross-sectional shape (S2) to the average value Wave2 of the length (W2) in the radial direction (y) of the cross-sectional shape (S2), is at least 1.25.

Description

In-vivo indwelling device

[0001] The present disclosure relates to an in-vivo indwelling device for forming an embolus in a blood vessel at a vascular diseased site.

[0002] As a minimally invasive treatment for cerebral aneurysms, endovascular therapy using a catheter or the like is known. For example, in one endovascular therapy method, an in-vivo indwelling device for embolization is inserted into a cerebral aneurysm through a catheter, cut at a detachment section, and a part of the in-vivo indwelling device is placed in the aneurysm to embolize the aneurysm. A part of the in-vivo indwelling device placed in the aneurysm acts as a physical barrier to blood flow, and thrombus formation around the placed part of the in-vivo indwelling device can reduce the risk of aneurysm rupture.

[0003] Patent Documents 1 and 2 disclose an in-vivo indwelling device for embolization that includes a coil, an elongation resistance member disposed inside the coil, and a tip disposed at the distal end of the coil. The in-vivo indwelling device is attached to the distal end portion of a pusher, and is pushed distally through a catheter or the like used for placement by the pusher, thereby being delivered to a target site in the body such as an aneurysm. Patent Document 3 discloses an in-vivo indwelling device in which a coil retains a drug to promote organization in the aneurysm.

[0004] Japanese National Publication of International Patent Application No. 2008-525113, International Publication No. WO 2019 / 026364, Japanese Unexamined Patent Publication No. 2015-195978

[0005] In the treatment of cerebral aneurysms and the like, an operation of pushing a pusher for a coil forward inside a catheter is performed. It has been found that interference caused by friction with the elongation resistance member disposed in the inner lumen of the coil is a cause of reduced slidability. That is, since the wire used for the coil is a round wire with a circular cross-sectional shape, the elongation resistance member may get into the gap between adjacent wires, which increases friction and may cause deterioration of slidability.

[0006] An object of the present disclosure is to provide an in-vivo indwelling device that can eliminate or reduce deterioration of slidability caused by foreign objects such as an elongation resistance member entering the gap between adjacent wires by devising the cross-sectional shape of the wire used for the coil.

[0007] The in-vivo implantable device according to this disclosure that can solve the above problems is as follows: [1] An in-vivo implantable device including a coil having a longitudinal axis direction and a radial direction, wherein the coil has a proximal coil formed by winding a first wire and a distal coil joined to the proximal coil and formed by winding a second wire, and the cross-sectional shape S1 of the first wire in a plane parallel to the longitudinal axis direction satisfies the following condition 1, and the cross-sectional shape S2 of the second wire in a plane parallel to the longitudinal axis direction satisfies the following condition 2. <Condition 1> The ratio Wmax1 / Wave1, which is the ratio of the maximum value Wmax1 of the radial length of the cross-sectional shape S1 to the average value Wave1 of the radial length of the cross-sectional shape S1, is 1.22 or less. <Condition 2> The ratio Wmax2 / Wave2, which is the ratio of the maximum value Wmax2 of the radial length of the cross-sectional shape S2 to the average value Wave2 of the radial length of the cross-sectional shape S2, is 1.25 or greater.

[0008] For a proximal coil, the ratio Wmax1 / Wave1, which is the ratio of the maximum radial length Wmax1 to the average radial length Wave1 of the wire's cross-sectional shape S1, is 1.22 or less. This results in a flat cross-sectional shape S1, such as a rectangle. For a distal coil, the ratio Wmax2 / Wave2, which is the ratio of the maximum radial length Wmax2 to the average radial length Wave2 of the wire's cross-sectional shape S2, is 1.25 or more. This results in a cross-sectional shape S2 that is raised in the radial direction of the coil, such as a circle. In other words, the proximal side of the coil can be shaped like a round wire coil, while the distal side can be shaped like a flat wire coil.

[0009] [2] The in-vivo implantation device according to [1], wherein the outer diameter of the proximal coil and the outer diameter of the distal coil are equal to each other. [3] The in-vivo implantation device according to [1], wherein the diameter of the coil joint formed by joining the distal end of the proximal coil and the proximal end of the distal coil is smaller than the larger of the diameter of the portion of the proximal coil other than the distal end and the diameter of the portion of the distal coil other than the proximal end. [4] The in-vivo implantation device according to [1], wherein the diameter of the coil joint formed by joining the distal end of the proximal coil and the proximal end of the distal coil is larger than the larger of the diameter of the portion of the proximal coil other than the distal end and the diameter of the portion of the distal coil other than the proximal end. [5] The in-vivo implantation device according to any one of [1] to [4], wherein the distal end of the proximal coil and the proximal end of the distal coil are joined by full-circumferential welding or full-circumferential adhesion. [6] An intravivo device according to any one of [1] to [4], wherein the distal end of the proximal coil and the proximal end of the distal coil are joined by welding at one or two locations in the circumferential direction of the coil. [7] An intravivo device according to any one of [1] to [4], wherein the distal end of the proximal coil and the proximal end of the distal coil are joined by adhesive at three or four locations in the circumferential direction of the coil. [8] An intravivo device according to any one of [1] to [7], wherein the cross-sectional shape of the first wire is rectangular and the cross-sectional shape of the second wire is circular. [9] An intravivo device according to any one of [1] to [8], having an extension-resistant member disposed in the lumen of the coil.

[10] An intravivo device according to [9], wherein a drug is applied to the surface of the coil and / or the surface of the extension-resistant member.

[11] The in-vivo implantation device according to

[10] , wherein, when a drug is applied to the surface of the coil, the drug applied to the proximal coil and the drug applied to the distal coil are different from each other.

[0010] According to the in-vivo implantation device of this disclosure, in clinical settings, the distal coil, which has a raised cross-sectional shape such as a circle, can flexibly accommodate the complex pathways at the distal end, while the proximal coil, which has a flat cross-sectional shape such as a rectangle, can improve the smoothness of the inside of the coil or widen the diameter of the lumen. This eliminates or reduces the deterioration of sliding performance caused by other objects such as stretch resistance members getting into the gaps between adjacent wires, thereby improving sliding performance.

[0011] Figure 1 shows a cross-sectional view of the main part of a coil used in an in-vivo implantable device, viewed from the side. Figure 1 shows an enlarged cross-sectional view of the cross-sectional shape of the wire used in the coil. Figure 3 shows a cross-sectional view of the coil of the in-vivo implantable device along the longitudinal axis direction, including the side view portion and the omitted portion, showing a cross-sectional view of the main part of the coil joint as seen from the side as an alternative embodiment 1. Figure 2 shows a cross-sectional view of the main part of the coil joint as seen from the side as an alternative embodiment 2. Figure 4 shows a basic cross-sectional view of the coil joint structure viewed from the proximal to distal side in the longitudinal axis direction. Figure 5 shows a cross-sectional view of the main part as seen from the side as an alternative embodiment of the coil joint as an alternative embodiment 2. Figure 6 shows a basic cross-sectional view of the coil joint structure viewed from the proximal to distal side in the longitudinal axis direction. Figure 7 shows a cross-sectional view of the main part as seen from the side as different cross-sectional shapes of the proximal and distal coils. Figure 8 shows an explanatory diagram showing various cross-sectional shapes superimposed at one-quarter each.

[0012] The contents of this disclosure will be described in more detail below based on the embodiments described below. However, the contents of this disclosure are not limited by the embodiments described below, and it is certainly possible to implement the disclosure with appropriate modifications within the scope that is consistent with the spirit of the preceding and following descriptions, and all such modifications are included within the technical scope of this disclosure. In addition, hatching and component reference numerals may be omitted in the drawings for convenience, in which case refer to the specification or other drawings. Furthermore, the dimensions of various components in the drawings may differ from the actual dimensions, as priority is given to helping to understand the features of this disclosure.

[0013] As shown in Figure 1, the in-vivo implantation device 1 according to this disclosure (see also Figures 3 and 4) includes a coil 2 having a longitudinal axis direction x, and a stretch resistance member 5, described later, is arranged in the lumen 4 of the coil 2, which is formed by spirally winding a wire 3. Figure 1 shows only the coil 2. The longitudinal direction x of the coil 2 is the length direction of the in-vivo implantation device 1 and is called the longitudinal axis direction x, and the radial direction y of the coil 2 is called the coil radial direction y, but is sometimes simply called the radial direction y. In addition, the outer diameter D of the coil 2 is sometimes called the coil outer diameter D, and the inner diameter N of the coil 2 is sometimes called the coil inner diameter N.

[0014] As shown in Figures 1 and 2, the coil 2 has a proximal coil 2A formed by winding a first wire 31 and a distal coil 2B joined to the proximal coil 2A and formed by winding a second wire 32. The in-vivo implantation device 1 is constructed such that the first cross-sectional shape S1, which is the cross-sectional shape of the first wire 31 in a plane parallel to the longitudinal axis x, satisfies the following condition 1, and the second cross-sectional shape S2, which is the cross-sectional shape of the second wire 32 in a plane parallel to the longitudinal axis x, satisfies the following condition 2.

[0015] <Condition 1> The ratio Wmax1 / Wave1, which is the ratio of the maximum value Wmax1 of the radial y length W1 of the first cross-sectional shape S1 to the average value Wave1 of the radial y length W1 of the first cross-sectional shape S1, is 1.22 or less. <Condition 2> The ratio Wmax2 / Wave2, which is the ratio of the maximum value Wmax2 of the radial y length W2 of the second cross-sectional shape S2 to the average value Wave2 of the radial y length W2 of the second cross-sectional shape Q2, is 1.25 or more.

[0016] In this specification, the proximal side of coil 2 refers to the direction toward the user or operator's hand with respect to the longitudinal axis x of coil 2, and the distal side refers to the opposite direction from the proximal side, i.e., the direction toward the treatment target. In Figure 1, which partially shows coil 2, the left side of the paper corresponds to the distal side and the right side of the paper corresponds to the proximal side, and the example shows that the center point B is at the halfway point of the length (total length) of the longitudinal direction x of coil 2. The proximal ends 2kt, 2Akt, and 2Bkt of each coil 2, 2A, and 2B are concepts that include the vicinity of each proximal end 2k, 2Ak, and 2Bk, and the distal ends 2et, 2Aet, and 2Bet are concepts that include the vicinity of each distal end 2e, 2Ae, and 2Be, and the distal ends 2e, 2Ae, and 2Be. Note that the reference numerals 2kt, 2Akt, 2et, and 2Bet are omitted in the drawings.

[0017] As shown in Figures 1 and 2, a preferred example of the first cross-sectional shape S1 is a rectangle in which the length L in the longitudinal axis direction x is longer than the length W in the radial direction (coil radial direction), and a preferred example of the second cross-sectional shape S2 is a circle with radius r. In other words, the proximal coil 2A is formed as a flat wire coil using a flat wire first wire 31, and the distal coil 2B is formed as a round wire coil using a round wire second wire 32. In Figures 1 and 2, a preferred example of coil 2 is shown in which the coil center diameter Ra of the proximal coil 2A and the coil center diameter Rb of the distal coil 2B are equal (Ra = Rb), but this is not limited to this. Furthermore, it is preferable that the proximal coil 2A and the distal coil 2B are joined to each other at the midpoint B, which is the point where the length x in the longitudinal direction (total length) of coil 2 is bisected, but this is not limited to this.

[0018] For the proximal coil 2A of the first wire 31, if the ratio Wmax1 / Wave1, which is the ratio of the maximum value Wmax1 of the radial y length in the first cross-sectional shape S1 to the average value Wave1 of the radial y length, is 1.22 or less, the proximal coil 2A will have a flat first cross-sectional shape S1, such as a rectangle. For the distal coil 2B of the second wire 32, if the ratio Wmax2 / Wave2, which is the ratio of the maximum value Wmax2 of the radial y length in the second cross-sectional shape S2 to the average value Wave2 of the radial y length, is 1.25 or more, the distal coil will have a second cross-sectional shape S2 that is raised in the radial direction of the coil, such as a circle. In other words, the proximal side of the coil can be made into a shape like a flat wire coil, and the distal side of the coil can be made into a shape like a round wire coil.

[0019] As a result, the proximal side of the coil, i.e., the first cross-sectional shape S1 of the proximal coil 2A, is flat, and the distal side of the coil, i.e., the second cross-sectional shape S2 of the distal coil 2B, is raised in the direction of the coil diameter. Therefore, in clinical practice, the distal side, where the pathway becomes more complex, can be flexibly adapted by using a second coil (round wire, etc.) made of a second round wire 32, while the proximal side can be improved by using the first coil (flat wire, etc.) to increase the smoothness of the inside of the coil or to increase the diameter of the lumen. This eliminates or reduces the deterioration of sliding performance caused by other objects such as extension resistance members getting into the gaps between adjacent wires, thereby improving sliding performance.

[0020] As shown in Figures 1 and 4, the coil 2 is formed by joining a proximal coil 2A, which is made by winding a first wire 31 having a rectangular first cross-sectional shape S1, and a distal coil 2B, which is made by winding a second wire 32 having a circular second cross-sectional shape S2, in the longitudinal axis direction x. As an example, Figures 1 and 2 depict the case where the first cross-sectional shape of the proximal coil 2A is a horizontally elongated rectangle that is slightly longer in the longitudinal axis direction x, and the diameter of its center in the radial direction y, i.e., the proximal coil center diameter Ra, and the coil center diameter Rb of the distal coil 2B having a circular second cross-sectional shape S2 are equal to each other.

[0021] It is preferable, but not limited to, that the distal end 2Ae of the proximal coil 2A and the proximal end 2Bk of the distal coil 2B are joined by full-circumferential welding or full-circumferential bonding. It is preferable to place a drug layer 6 containing drug m or drug m on the outer circumferential surface 8 or inner circumferential surface 9 of the coil 2. Furthermore, cross-sectional shapes S1 and S2 in which grooves 14 are formed on the inside and outside of the radial direction y of each wire 31 and 32 are also preferable, and it is even preferable if the aforementioned drug m or drug layer 6 is also placed in the grooves 14. The grooves 14 may be provided in part or all of each coil 2A and 2B.

[0022] As shown in Figure 1, when the length of the cross section of the wire 3 cut along the longitudinal axis x is L and the length of the radial axis y is W, as shown in Figure 2, in the first rectangular cross-sectional shape S1 having a longitudinal axis x length L1 and a radial axis y length W1, the maximum value Wmax1 of the radial axis y length W1 and the average value Wave1 of the radial axis y length W1 are equal to each other (Wmax1 = Wave1). In the second cross-sectional shape S2, since the cross section is circular, the longitudinal axis x length L2 (notation omitted in Figure 2) is 2r, and the radial axis y length W2 (notation omitted in Figure 2) is also 2r and Wmax2.

[0023] [Regarding Wmax / Wave of Cross-Sectional Shape S] The Wmax / Wave representing the flatness of the cross-sectional shape S of the wire 3 will be explained. The Wmax / Wave of the distal coil 2B and the proximal coil 2A will be explained separately. The first cross-sectional shape S1 and the second cross-sectional shape S2 shown in Figures 1 and 2 are depicted as an example where the coil center diameters Ra and Rb are equal to each other, and the section modulus with respect to the radial direction y is equal to each other. Therefore, in the figures shown in Figures 1 and 2, the radial y length W of the first cross-sectional shape S1 is 0.785 times the radial y length W of the second cross-sectional shape S2 (rounded to four decimal places).

[0024] <Regarding the distal coil 2B> The circular second cross-sectional shape S2 shown in Figures 1 and 2 is a round wire, and we determine the second cross-sectional shape S2 of the second wire 32 having this circular cross-section. The average value of the radial y length W2 of the second cross-sectional shape S2, Wave2 = Area of ​​the second cross-sectional shape S2 ÷ Maximum length x in the longitudinal direction, i.e., πr2 / 2r = 1.571r (rounded to four decimal places), and the maximum value of the radial y length W2, Wmax2, is 2r, so Wmax2 / Wave2 = 1.273 (rounded to four decimal places). In other words, by the above quantification, the flatness of the second cross-sectional shape S2 of the distal coil 2B, Wmax2 / Wave2 = 1.273, is greater than the flatness threshold of 1.25, so it satisfies the condition "Wmax2 / Wave2 is 1.25 or greater" and is preferable.

[0025] <Regarding the proximal coil 2A> In the rectangular first cross-sectional shape S1 shown in Figures 1 and 2, if the length in the longitudinal direction x is L1 and the length in the coil radial direction y is W1, then the maximum value of the coil radial direction y length Wmax1 is equal to W1. Furthermore, the average value Wave1, which is the value obtained by dividing the area of ​​the first cross-sectional shape S1 by the length in the longitudinal direction x L1, and the radial direction y length W1 are equal to each other, so W1 = Wmax1 = Wave1. Note that the four corner radii of the first cross-sectional shape S1 are sufficiently small and can be ignored in the calculation.

[0026] The flatness of the simple rectangular first cross-sectional shape S1 shown in Figures 1 and 2, Wmax1 / Wave1, is "1" because, as mentioned above, Wmax1 = Wave1. This is smaller than the flatness threshold of 1.22, so it satisfies the condition "Wmax1 / Wave1 is 1.22 or less" and is therefore preferable. Thus, the numerical values ​​show that the first cross-sectional shape S1 is sufficiently flatter than the circular second cross-sectional shape S2 (conventional round wire).

[0027] As shown in Figure 1, the cross-sectional shape of the first wire 31 forming the proximal coil 2A can also be a rectangle with a groove 14 shown by a dashed line. For example, consider the case where there is a groove 14 opening on the outer surface 8. As a specific example, if the width of the groove 14 is L / 4 and the depth is W / 4, then L = 4W / 3, then Wave = Area of ​​cross-sectional shape S ÷ L = (L × W - (L / 4 × W / 4)) ÷ L = (15 / 16)LW = 15 / 16 × W. Since the maximum value Wmax of the coil radial y length is W, as a result, Wmax / Wave of the cross-sectional shape S of the rectangular cross-sectional shape with groove 14 = W / (15W / 16) = 16 / 15 = 1.067 (rounded to four decimal places), which is smaller than the flatness threshold of 1.22. Therefore, it is preferable that the proximal coil 2A substantially satisfies the condition that "Wmax1 / Wave1 is 1.22 or less".

[0028] As shown in Figure 1, the cross-sectional shape of the second wire 32 forming the distal coil 2B can also be a circular shape with a groove 14, indicated by a dashed line. For example, consider the case where there is a groove 14 opening on the outer surface 8. Due to the presence of the groove 14, the area of ​​the cross-sectional shape S is smaller than the area of ​​the second cross-sectional shape S2 without the groove 14, so the average length Wave in the radial direction y is also smaller than Wave 2. And, although the maximum length Wmax in the radial direction y is slightly less than 2r due to the groove 14 located in the center in the longitudinal axis direction x, if the groove 14 is of the size shown in Figure 1, it is 1.96r (approximately 2r), so without even needing to perform detailed calculations, it will not be smaller than the value of 1.273 for the circular first cross-sectional shape S1. Therefore, the Wmax / Wave of the circular cross-sectional shape S with groove 14 in the distal coil 2B is 1.273 or greater, which is greater than the flatness threshold of 1.25, so it substantially satisfies the condition "Wmax2 / Wave2 is 1.25 or greater" and is therefore preferable.

[0029] As shown in Figures 1 and 2, if the section modulus with respect to the radial y direction is made the same for the first cross-sectional shape S1 and the second cross-sectional shape S2, and the strength and rigidity of the proximal coil 2A made of flat wire is the same as that of the distal coil 2B made of round wire, then the coil inner diameter Na of the proximal coil 2A becomes larger than the coil inner diameter Nb of the distal coil 2B, and the coil outer diameter Da of the proximal coil 2A becomes smaller than the coil outer diameter Db of the distal coil 2B. Therefore, in the proximal coil 2A, it is possible to enlarge the coil inner diameter and reduce the coil outer diameter compared to the distal coil 2B. The following effects and advantages can be obtained by changing the cross-section of the wire 3 from circular to rectangular, and these are considered preferable.

[0030] Physically increasing the diameter of the lumen 4 of the coil 2 reduces the opportunity for physical contact between the coil 2 and components arranged in the lumen 4, such as the stretch resistance member 5 (see Figure 4), thereby improving sliding properties, which is preferable. Physically reducing the outer diameter of the coil also reduces the opportunity for contact with components arranged outside the diameter of the coil, such as the inner wall of a blood vessel or a guiding catheter, which reduces the risk of damaging living tissue such as blood vessels and improves sliding properties, which is also preferable. Furthermore, by making the cross-sectional shape rectangular, the winding density of the coil 2 can be improved, making it possible to wind the coil more compactly by shortening the length in the longitudinal direction compared to a wire with a circular cross-section (round wire).

[0031] As the irregularities on the outer circumferential surface 8 and inner circumferential surface 9 of the coil 2 are reduced or flattened, friction caused by the extension resistance member 5 entering gaps between adjacent wires is eliminated or reduced, thereby reducing friction with other objects placed in the lumen 4 or on the outside of the coil 2, and improving sliding properties. Furthermore, when applying a drug or hydrophilic coating layer to the surface of the coil 2 by spraying or the like, the drug tends to flow into the gaps and cause unevenness in coils made of round wires, but in coils made of wires with a rectangular cross-section, it becomes possible to distribute the drug more uniformly.

[0032] <Regarding Wmax / Wave> It is physically impossible for the maximum value Wmax of the coil radial length W of the cross-sectional shape S to be smaller than the average value Wave of the coil radial length W. Therefore, when Wmax1 / Wave1 of the first cross-sectional shape S1 is 1.22 or less, it is essentially the same as Wmax1 / Wave1 being 1 or more and 1.22 or less, i.e., "1 ≤ Wmax1 / Wave1 ≤ 1.22". In that case, when the first cross-sectional shape S1 of the first wire 31 forming the proximal coil 2A is a simple rectangle (see Figure 2), as mentioned above, "Wmax1 / Wave1 = 1", and the inner and outer surfaces 8 and 9 of the coil are both perfectly flat without any irregularities or undulations in the longitudinal axis direction x, which is very preferable. Furthermore, it is more preferable if the threshold for flatness, Wmax1 / Wave1, is 1.20 or less, and even more preferable if it is 1.18 or less.

[0033] In the distal coil 2B, it is desirable that the inner and outer shapes are round in the radial direction y. As mentioned above, Wmax2 / Wave2, which represents the flatness of the second cross-sectional shape S2 with a circular cross-section, is 1.273. Therefore, the definition of "Wmax2 / Wave2 is 1.25 or greater" is preferable. However, the upper limit in this case should be considered with reference to Figure 9.

[0034] Figure 9 shows one-quarter of each of the three cross-sectional shapes S2, Sm, and Sh superimposed on the x and y axes. These represent one-quarter each of the circular second cross-sectional shape S2 (shown by a solid line), the rounded rhombus cross-sectional shape Sm (shown by a dashed line), and the rhombus cross-sectional shape Sh (shown by a dashed line). As the second cross-sectional shape S2 is gradually changed from the circular shape shown by the solid line to the rhombus cross-sectional shape Sh shown by the dashed line, while keeping the section modulus with respect to the y axis constant, the points where it intersects the x and y axes become progressively sharper. The points x2 and y2 where the rounded rhombus cross-sectional shape Sm intersects the x and y axes are larger than the points x1 and y1 where it intersects the x and y axes in the second cross-sectional shape S2, and the points x3 and y3 where it intersects the x and y axes in the rhombus cross-sectional shape Sh become even larger. In the case of the rhombus cross-section Sh, which is a square tilted at 45 degrees, the calculation is omitted, but Wmax / Wave = 2, which is significantly greater than 1.25.

[0035] In the rhombic cross-sectional shape Sh, when the radius of the circle is r, both x3 and y3 are approximately 1.33r. When this is used as a wire, it not only becomes pointed in the coil radial direction y and longitudinal direction x, but the coil outer diameter becomes large and the coil inner diameter becomes small, resulting in an undesirable cross-sectional shape for a coil wire. In the rounded rhombic cross-sectional shape Sm shown in Figure 9, it is also a shape that protrudes sharply in both the x and y axes, so although detailed calculations are omitted, the Wmax / Wave of the cross-sectional shape Sm is approximately 1.7.

[0036] As described above, as the shape of the second cross-sectional shape S2 changes from circular to rhombic, the coil outer diameter Db increases and the coil inner diameter Nb decreases, and Wmax2 / Wave2 gradually increases from 1.25. Therefore, it is presumed that the upper limit of Wmax2 / Wave2 for the distal coil 2B is preferably around 1.5. In other words, it is considered preferable that Wmax2 / Wave2 for the distal coil 2B is between 1.25 and 1.50. Furthermore, it is more preferable if Wmax2 / Wave2 is between 1.255 and 1.40, and even more preferable if it is between 1.26 and 1.35.

[0037] [Intra-vivo implantable devices] Examples of the use of intra-vivo implantable devices include embolization to promote thrombosis at target sites such as cerebral aneurysms, head and neck aneurysms, arteriovenous malformations, arteriovenous fistulas, pulmonary vascular malformations, renal vascular malformations, renal artery aneurysms, and abdominal aneurysms. Among these, intra-vivo implantable devices for cerebral aneurysms are preferred. The shape of the aneurysm can be fusiform or saccular.

[0038] Figure 3 is a schematic diagram of catheter A including the in-vivo implantation device 1 and pusher 7, and Figure 4 is a cross-sectional view of the in-vivo implantation device 1 along the longitudinal axis direction of the coil, including a partial side view, and for simplicity, some parts are shown only as outlined by dashed lines. As shown in Figure 4, in the in-vivo implantation device 1, the coil 2 has a longitudinal axis direction x, a radial direction y, and a circumferential direction z. The coil 2 has a distal end 2e and a proximal end 2k along the longitudinal axis direction x. The proximal side of the coil 2 refers to the direction toward the user or operator's hand with respect to the longitudinal axis direction x of the coil 2, and the distal side refers to the opposite direction from the proximal side, i.e., the direction toward the target of treatment.

[0039] As shown in Figure 4, the coil 2 has a proximal coil 2A formed by winding a first wire 31 which is a wire 3, and a distal coil 2B which is joined to the proximal coil 2A and formed by winding a second wire 32 which is a wire 3. Preferably, the proximal coil 2A is formed as a flat wire coil using the first wire 31 which has a first cross-sectional shape S1 (see Figures 1 and 2) with a rectangular cross-section that is slightly longer in the longitudinal axis x, and the distal coil 2B is formed as a round wire coil using the second wire 32 which has a second cross-sectional shape S2 (see Figures 1 and 2) with a circular cross-section.

[0040] In Figure 4, as an example, it is preferable to assume that the midpoint B, which bisects the entire length of coil 2 in the longitudinal axis direction x, is slightly to the left of the portion cut off by the pair of break lines (on the left side of the page in Figure 4), and that the area to the right of midpoint B is called the proximal coil portion 2A, and the area to the left of midpoint B is called the distal coil portion 2B. The radial direction y of coil 2 refers to the radial direction of coil 2, and in the radial direction y, inward refers to the direction toward the longitudinal axis center of coil 2, and outward refers to the direction extending radially from the longitudinal axis center on the opposite side from inward. The circumferential direction z of coil 2 refers to the direction around the longitudinal axis.

[0041] As shown in Figure 4, the coil 2 has an outer circumferential surface 8 and an inner circumferential surface 9. In the proximal coil 2A, the outer circumferential surface 8 and the inner circumferential surface 9 are the long sides of a rectangle and are planar, while in the distal coil portion 2B, the outer circumferential surface 8 and the inner circumferential surface 9 are substantially wavy, consisting of a series of semicircular arcs. The surface of the coil 2 includes the outer circumferential surface 8 and the inner circumferential surface 9, and also includes the groove 14 (see Figure 1) if a groove 14 is formed in the wire 3. It is preferable that the coil 2 has a lumen 4 extending in the longitudinal axis direction x. The outer circumferential surface 8 of the coil 2 basically faces the outside of the coil 2, i.e., the outside in the radial direction y, and the inner circumferential surface 9 of the coil 2 basically faces the lumen 4. It is preferable that a stretch resistance member 5, which will be described later, is placed in the lumen 4. Figure 4 shows a structure in which a drug layer 6 or drug m is placed on each of the outer circumferential surface 8 and the inner circumferential surface 9 of the coil 2. Note that a hydrogel may be placed on the inner circumferential surface 9 instead of the drug layer 6.

[0042] As shown in FIGS. 3 and 4, the coil 2 is preferably configured by helically winding one or more wires 3, and a configuration including a proximal coil 2A formed of a first wire 31 and a distal coil 2B formed of a second wire 32 is also preferable. Examples of the wire 3 include a single wire, a stranded wire, and a coil wire wound in a coil shape, and a single wire is particularly preferable. As shown in FIGS. 1 and 2, the wires 3 preferably include a first wire 31 having a first cross-sectional shape S1 with a rectangular cross-section and a second wire 32 having a second cross-sectional shape S2 with a circular cross-section, but are not limited thereto.

[0043] The wire 3 preferably has biocompatibility and flexibility. Examples of the material constituting the wire 3 include platinum, gold, titanium, tungsten, alloys thereof, metal materials such as stainless steel, and combinations thereof. Among these, it is more preferable that the wire 3 is made of a platinum-tungsten alloy.

[0044] It is preferable that the proximal coil 2A and the distal coil 2B have a constant outer diameter in the longitudinal axis direction x. The expression "outer diameter is constant" means that the outer diameters of the coils 2A and 2B are substantially constant over the entire longitudinal axis direction x of the coils 2A and 2B, and includes those in which the change in the outer diameter of the coil 2 falls within the range of ±5% over the entire longitudinal axis direction x. In FIGS. 1 and 4, a configuration is shown in which the center diameters Ra and Rb of the proximal coil 2A and the distal coil 2B are equal to each other. As will be described in detail later, a configuration in which the outer diameters Da and Db of the coils are equal to each other and a configuration in which the inner diameters Na and Nb of the coils are equal to each other are also preferable.

[0045] As shown in Figure 4, it is preferable that a drug layer 6 containing drug m and a base material is disposed on the surface of the coil 2, and it is preferable that the base material is more abundant than the drug m by mass ratio. The substance containing drug m and base material s is called the drug, and the drug applied to the outer circumferential surface 8 and / or inner circumferential surface 9 of the coil 2 is called the drug layer 6. It is also acceptable to have a configuration in which drug m is disposed on the surface of the coil 2. Drug m preferably contains at least one of the following: an anti-inflammatory agent, an antioxidant, an antihypertensive agent, and a vasoconstrictor inhibitor. It is preferable, but is not limited to, that the drug layer 6 or drug m disposed on the surface of the proximal coil 2A and the drug layer 6 or drug m disposed on the surface of the distal coil 2B are different from each other. Although not shown in the figure, it is also preferable that drug m or drug layer 6 is disposed on the surface of the extension resistance member 5, and drug m or drug layer 6 may be the same as or different from those disposed on the coil 2.

[0046] As shown in Figure 4, the in-vivo implantation device 1 preferably has an extension resistance member 5 positioned in the lumen 4 of the coil 2. The extension resistance member 5 suppresses the stretching of the coil 2 in the longitudinal axis direction x during operation. The extension resistance member 5 is preferably formed from a long member consisting of a single wire or stranded wire. The extension resistance member 5 has a longitudinal axis direction and has a first end and a second end in that longitudinal axis direction. The extension resistance member 5 is preferably composed of one or more layers in the radial direction perpendicular to the longitudinal axis direction. The extension resistance member 5 preferably has an inner layer composed of stranded wire made of multiple wires and an outer layer provided outside the inner layer and containing a resin composition. It is preferable that one or more extension resistance members 5 are positioned in the lumen 4.

[0047] The elongation resistance member 5, which is formed of a wire bent into a wavy shape, is preferably made of resin or metal. Examples of resins for forming the elongation resistance member 5 include polyester resins such as polyethylene terephthalate, polyamide resins such as nylon, and polyolefin resins such as polyethylene and polypropylene. Being made of resin enhances flexibility and improves the delivery performance of the in-vivo indwelling device 1. Furthermore, forming the elongation resistance member 5 from resin can eliminate breakage caused by metal fatigue during delivery. By making the length of the elongation resistance member 5 longer than that of the coil 2, or using a material that is easily stretchable for the elongation resistance member 5, it is possible to alleviate the tension caused when the end portion of the coil 2 stretches linearly due to insufficient length of the elongation resistance member 5 when the coil 2 is placed in an aneurysm. Examples of metals for forming the elongation resistance member 5 include platinum, gold, rhodium, palladium, rhenium, silver, nickel, titanium, tantalum, tungsten, alloys thereof, and stainless steel.

[0048] The elongation resistance member 5 is made of a material different from that of the wire 3 constituting the coil 2, or made of the same material. For example, a combination is conceivable in which the coil 2 is made of a platinum-tungsten alloy and the elongation resistance member 5 is made of polypropylene resin, but the combination is not limited thereto. The elongation resistance member 5 can have various cross-sectional shapes perpendicular to its longitudinal axis, such as circular, oval, polygonal, or combinations thereof.

[0049] To facilitate arrangement of the elongation resistance member 5 in the lumen 4, the outer diameter of the elongation resistance member 5 is preferably smaller than one half of the inner diameter N of the coil 2 (see FIG. 1), and more preferably one third or less thereof. To prevent breakage of the elongation resistance member 5, the outer diameter of the elongation resistance member 5 is preferably one fifteenth or more of the inner diameter N of the coil 2, and more preferably one tenth or more thereof. The elongation resistance member 5 can be linear, wavy, helical, or a combination of these shapes.

[0050] The first end of the extension resistance member 5 may be connected to the distal end 2et of the coil 2, specifically to the distal end 2Bet of the second wire 32 constituting the distal coil 2B. The second end of the extension resistance member 5 may be connected to the proximal end 2kt of the coil 2, specifically to the proximal end 2Akt of the first wire 31 constituting the proximal coil 2A. The second end of the extension resistance member 5 may be connected to the connection portion 11 that connects the coil 2 and the pusher 7. The extension resistance member 5 may be placed in the lumen 4 in a folded state midway along the longitudinal axis x of the extension resistance member 5. In that case, it is preferable that the folded portion 5a of the extension resistance member 5 is connected to the distal end 2et or proximal end 2kt of the coil 2, and the first end and the second end are connected to the proximal end 2kt or distal end 2et of the coil 2, or to the distal end of the connection portion 11. For example, in Figure 4, the extension resistance member 5 has a folded portion 5a that is folded back in the middle of the longitudinal axis x, the folded portion 5a is connected to the distal end 2et of the coil 2, and the first end and second end are connected to the distal end 11a of the connection portion 11.

[0051] Methods for connecting the extension resistance member 5 to other members include physical fixing methods such as welding, crimping, adhesive bonding, engagement, linking, binding, and ligation, or combinations thereof. Here, "connection" includes both forms in which the two elements are directly connected and forms in which the two elements are indirectly connected through one or more other elements.

[0052] As shown in Figures 3 and 4, it is preferable that the coil 2 has a head portion 12 at its distal end 2et. It is preferable that the head portion 12 covers a part of the second wire 32 to avoid the distal end of the second wire 32 directly contacting the inner wall surface of the living body. The shape of the head portion 12 is not particularly limited, but examples include hemispherical, semi-elongated spherical, cylindrical, polygonal prism, etc.

[0053] The head portion 12 is preferably joined to at least one of the outer or inner surfaces of the coil 2. To prevent the head portion 12 from falling off, a part of the head portion 12 is preferably positioned in the lumen 4 of the distal end 2Bet of the distal coil 2B. In Figure 4, the proximal end of the head portion 12 is positioned proximal to the distal end of the second wire 32, but a configuration in which the proximal end of the head portion 12 is positioned distal to the distal end of the second wire 32 is also possible. Furthermore, it is preferable that a tail portion 13 is provided at the proximal end 2kt of the coil 2, specifically the proximal end 2Akt of the proximal coil 2A, to close the proximal end 2kt of the coil 2. The distal portion of the tail portion 13 is positioned on the inner diameter side of the drug layer 6, but it may also be positioned directly on the inner diameter side of the coil 2.

[0054] The head portion 12 is preferably made of a metal material or a resin. Examples of resins that make up the head portion 12 include thermoplastic resins and ultraviolet curing resins. Examples of resins that make up the head portion 12 include ester resins such as epoxy acrylate resins, urethane acrylate resins, polyester acrylate resins, and polyethylene terephthalate resins, and olefin resins such as polypropylene. As the metal that makes up the head portion 12, the metals mentioned in the description of the wire 3 can be used. It is preferable that the material of the wire 3 and the material of the head portion 12 are the same, but this is not limited to the present invention.

[0055] [Various Other Embodiments] As shown in Figure 5, the in-vivo implantation device 1 may also have coils 2 in which the outer diameter Da of the proximal coil 2A and the outer diameter Db of the distal coil 2B are equal to each other. In this case, the coil center diameter Ra of the proximal coil 2A, which has a rectangular cross-section, is larger than the coil center diameter Rb of the distal coil 2B, which has a circular cross-section. Adopting such a configuration is preferable because, compared to the configuration shown in Figures 1 and 2, i.e., the configuration in which the coil center diameter Ra of the proximal coil 2A and the coil center diameter Rb of the distal coil 2B are equal to each other, the degree to which the diameter of the lumen 4 of the proximal coil 2A is larger than the diameter of the lumen 4 of the distal coil 2B is greater, and the sliding properties of the proximal coil 2A are further improved.

[0056] As shown in Figure 5, it is preferable that the diameter Dc of the coil joint 2C formed by joining the distal end 2Aet of the proximal coil 2A and the proximal end 2Bkt of the distal coil 2B is smaller than the larger of the diameter of the portion of the proximal coil 2A other than the distal end 2Aet and the diameter of the portion of the distal coil 2B other than the proximal end 2Bkt. In Figure 5, the vicinity of the joint 2C of each coil 2A and 2B is shown, and one side of the cross-section in the radial direction y is shown, and the diameter Dc of the coil joint 2C is smaller in radius u than the outer diameter D of the coil. By adopting such a configuration, it is possible to make the structure more compact, such as by offsetting the increase in diameter of the joint 2C due to the protrusion of the welding or bonding area 15 for joining the distal end 2Aet of the proximal coil 2A and the proximal end 2Bkt of the distal coil 2B, and improving the operability of the joint 2C.

[0057] As shown in Figure 6, it is also preferable that the diameter Dc of the coil joint 2C, formed by the joining of the distal end 2Aet of the proximal coil 2A and the proximal end 2Bkt of the distal coil 2B, is larger than the larger of the diameter Da of the portion of the proximal coil 2A other than the distal end 2Aet and the diameter Db of the portion of the distal coil 2B other than the proximal end 2Bkt. In Figure 6, a configuration is shown in which the coil center diameter 16 of the first wire 31 of the distal end 2Aet having the distal end 2Ae is equal to the coil center diameter 17 of the second wire 32 of the proximal end 2Bkt having the proximal end 2Bk (the same structure as shown in Figures 1 and 2), where Db > Da. Therefore, in the configuration shown in Figure 6, the diameter Dc of the coil joint 2C is larger than the outer coil diameter Db of most of the distal coil 2B. Adopting this configuration is preferable because it increases the diameter of the coil joint 2C compared to the proximal and distal coils 2A and 2B, thereby improving the joint strength between the proximal coil 2A and the distal coil 2B.

[0058] As shown in Figure 7, a configuration in which the distal end 2Ae of the proximal coil 2A and the proximal end 2Bk of the distal coil 2B are joined by welding 15y at one or two locations in the coil circumferential direction z is preferred, and a configuration in which the distal end 2Ae of the proximal coil 2A and the proximal end 2Bk of the distal coil 2B are joined by bonding 15t at three or four locations in the coil circumferential direction z is also preferred. An example of welding is welding, and an example of bonding is adhesive bonding, but these are not the only examples. As shown in Figure 7, for example, the welding 15y, which is the location of the hatching sloping downward to the right, is applied at two locations 180 degrees apart around the longitudinal axis x, and for example, the bonding 15t, which is the location of the hatching sloping downward to the left, is applied at three locations 120 degrees apart around the longitudinal axis x.

[0059] As shown in Figure 8, the cross-sectional shape S of the proximal coil 2A is preferably a semicircular cross-sectional shape Sk (also called a horizontal D-shape) shown by a solid line, or a square cross-sectional shape Ss shown by a dashed line, which is an example of a rectangle; the important thing is that Wmax1 / Wave1 is 1.20 or less. The cross-sectional shape of the distal coil 2B is preferably an elliptical cross-sectional shape Sy, which is elongated in the radial direction y, shown by a solid line, or an elliptical cross-sectional shape Sx, which is elongated in the longitudinal axis direction x; the important thing is that Wmax2 / Wave2 is 1.25 or more. Note that hatching is omitted in Figure 8 because the shapes are drawn overlapping.

[0060] This application claims the benefit of priority based on Japanese Patent Application No. 2025-52302, filed on 26 March 2025. The entire specification of Japanese Patent Application No. 2025-52302, filed on 26 March 2025, is incorporated herein by reference.

[0061] 2 Coil 2A Proximal coil 2Aet Distal end of proximal coil 2B Distal coil 2Bkt Proximal end of distal coil 2C Coil joint 3 Wire 4 Lumen 5 Stretch resistance member 15 Circumferential welding or adhesive 15t Adhesion 15y Welding 31 First wire 32 Second wire Da Outer diameter of proximal coil Db Outer diameter of distal coil S Cross-sectional shape S1 First cross-sectional shape S2 Second cross-sectional shape W Radial length of cross-sectional shape W1 Radial length of first cross-sectional shape W2 Radial length of second cross-sectional shape Wave Average value of radial length Wave1 Average value of radial length of first cross-sectional shape Wave2 Average value of radial length of second cross-sectional shape Wmax Maximum value of radial length of cross-sectional shape Wmax1 Maximum radial length of the first cross-sectional shape: Wmax² Maximum radial length of the second cross-sectional shape: m Drug x Longitudinal axis direction y Radial direction

Claims

1. An in-vivo implantation device including a coil having a longitudinal axis direction and a radial direction, wherein the coil comprises a proximal coil formed by winding a first wire and a distal coil joined to the proximal coil and formed by winding a second wire, and the cross-sectional shape S1 of the first wire in a plane parallel to the longitudinal axis direction satisfies the following condition 1, and the cross-sectional shape S2 of the second wire in a plane parallel to the longitudinal axis direction satisfies the following condition 2. <Condition 1> The ratio Wmax1 / Wave1, which is the ratio of the maximum value Wmax1 of the radial length of the cross-sectional shape S1 to the average value Wave1 of the radial length of the cross-sectional shape S1, is 1.22 or less. <Condition 2> The ratio Wmax2 / Wave2, which is the ratio of the maximum value Wmax2 of the radial length of the cross-sectional shape S2 to the average value Wave2 of the radial length of the cross-sectional shape S2, is 1.25 or more.

2. The in-vivo device according to claim 1, wherein the outer diameter of the proximal coil and the outer diameter of the distal coil are equal to each other.

3. The in-vivo implantation device according to claim 1, wherein the diameter of the coil joint formed by joining the distal end of the proximal coil and the proximal end of the distal coil is smaller than the larger of the diameter of the portion of the proximal coil other than the distal end and the diameter of the portion of the distal coil other than the proximal end.

4. The in-vivo implantation device according to claim 1, wherein the diameter of the coil joint formed by joining the distal end of the proximal coil and the proximal end of the distal coil is greater than the larger of the diameter of the portion of the proximal coil other than the distal end and the diameter of the portion of the distal coil other than the proximal end.

5. The in-vivo implantation device according to any one of claims 1 to 4, wherein the distal end of the proximal coil and the proximal end of the distal coil are joined by full-circumferential welding or full-circumferential adhesion.

6. The in-vivo implantation device according to any one of claims 1 to 4, wherein the distal end of the proximal coil and the proximal end of the distal coil are joined by welding at one or two locations in the circumferential direction of the coil.

7. The in-vivo implantation device according to any one of claims 1 to 4, wherein the distal end of the proximal coil and the proximal end of the distal coil are joined by adhesive at three to four locations in the circumferential direction of the coil.

8. The in-vivo implantation device according to any one of claims 1 to 4, wherein the cross-sectional shape of the first wire is rectangular and the cross-sectional shape of the second wire is circular.

9. An in-vivo implantation device according to any one of claims 1 to 4, comprising an extension resistance member disposed in the lumen of the coil.

10. The in-vivo device according to claim 9, wherein a drug is applied to the surface of the coil and / or the surface of the stretch resistance member.

11. The in-vivo implantation device according to claim 10, wherein, when a drug is applied to the surface of the coil, the drug applied to the proximal coil and the drug applied to the distal coil are different from each other.

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