Embolic coil

Abstract

An embolic coil is formed by being spirally wound by an element wire and is filled into an aneurysm. The embolic coil includes: a first coil portion, in which a large-diameter coil portion wound to have a large diameter D1 and a small-diameter coil portion wound to have a diameter D2 smaller than the large-diameter coil portion are arranged in a plurality of coils and alternately in a longitudinal direction Y of the embolic coil. A second coil portion is wound to be continuous with the first coil portion and to have a surface flatter than the first coil portion.

Claims

1. An embolic coil formed by being spirally wound by an element wire to be filled into an aneurysm, comprising: a first coil portion that contains at least three large-diameter coil portions wound to have a large diameter and at least three small-diameter coil portions wound to have a diameter smaller than that of the large-diameter coil portions, said the large-diameter coil portions and the small-diameter coil portions being alternately present in a longitudinal direction of the embolic coil; and a second coil portion, which is continuous with the first coil portion and wound to have a flatter surface than the first coil portion, wherein the second coil portion is at least three times longer than the large-diameter coil portions of the first coil portion in the longitudinal direction, each of the large-diameter coil portions has a maximum outer diameter in a center and an outer diameter of each of the large-diameter coil portions decreases gradually and symmetrically in the longitudinal direction, and the first coil portion contains the small-diameter coil portions between the adjacent large-diameter portions that are directly connected thereto.

2. The embolic coil according to claim 1, characterized in that an outer diameter of the second coil portion is the same as a maximum outer diameter of each of the large-diameter coil portions.

3. The embolic coil according to claim 1, characterized in that the first coil portion having a predetermined length is positioned at a distal end of the embolic coil.

4. The embolic coil according to claim 3, characterized in that a portion of the distal end of the embolic coil continuing to the first coil portion is provided with the second coil portion having a length longer than the first coil portion.

5. The embolic coil according to claim 1, characterized in that the first coil portion having a predetermined length and the second coil portion having a predetermined length are repeatedly provided in the longitudinal direction.

6. The embolic coil according to claim 1, characterized in that each of the large-diameter coil portions is wound such that an outer surface forms a spherical convex curved surface.

7. The embolic coil according to claim 1, characterized in that each of the small-diameter coil portions is wound such that an outer surface forms a spherical concave curved surface.

8. The embolic coil according to claim 1, characterized in that a primary shape, in which the first coil portion and the second coil portion are formed, is formed relative to the wire, and a secondary shape used for forming a frame is formed relative to a predetermined length portion of a distal end of the embolic coil.

9. The embolic coil according to claim 1, wherein a length of the second coil portion in the longitudinal direction is the same or longer than a length of the first coil portion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other features and advantages of the present invention will become more readily appreciated when considered in connection with the following detailed description and appended drawings, wherein like designations denote like elements in the various views, and wherein:

(2) FIG. 1 is an explanatory diagram showing an outline of catheter treatment using an embolic coil.

(3) FIG. 2 is a view showing a first embodiment of the present invention, and is a side view showing a primary shape of an embolic coil.

(4) FIG. 3 is a view showing a first embodiment of the present invention, and is a side view showing a secondary shape of an embolic coil.

(5) FIG. 4 is a view showing a first embodiment of the present invention, and is an explanatory diagram showing an embolic coil before starting to guide.

(6) FIG. 5 is a view showing a first embodiment of the present invention and is an explanatory diagram explaining the formation of the frame.

(7) FIG. 6 is a view showing a first embodiment of the present invention, and is an explanatory diagram explaining formation of the frame in an irregularly shaped aneurysm.

(8) FIG. 7 is a view showing a second embodiment of the present invention, and is a side view showing a primary shape of an embolic coil.

(9) FIG. 8 is a view showing a second embodiment of the present invention, and is a side view showing a secondary shape of an embolic coil.

(10) FIG. 9 is a view showing a second embodiment of the present invention, and is an explanatory diagram showing an embolic coil before starting to guide.

(11) FIG. 10 is a view showing a second embodiment of the present invention, and is an explanatory diagram explaining formation of the frame.

(12) FIG. 11 is a view showing a second embodiment of the present invention, and is an explanatory diagram showing a state in which guiding of an embolic coil has proceeded further from formation of the frame.

(13) FIG. 12 is a view showing a second embodiment of the present invention, and is an explanatory diagram explaining frame formation in an irregularly shaped aneurysm.

(14) FIG. 13 is a view showing a second embodiment of the present invention, and is an explanatory diagram showing a state in which guiding of an embolic coil has proceeded further from forming the frame in an irregularly shaped aneurysm.

(15) FIG. 14 is a view showing a second embodiment of the present invention, and is a schematic view showing an example of the filling state of the embolic coil after completion of filling.

(16) FIG. 15 is a view showing a first embodiment of the present invention, and is a schematic view showing an example of the embolic coil filling state after completion of filling.

(17) FIG. 16 is a view showing a third embodiment of the present invention, and is a side view showing a primary shape of an embolic coil.

(18) FIG. 17 is a view showing a fourth embodiment of the present invention, and is a side view showing a primary shape of an embolic coil.

(19) FIG. 18 is a view showing a fifth embodiment of the present invention, and is a side view showing a primary shape of an embolic coil.

DETAILED DESCRIPTION OF THE INVENTION

(20) An embolic coil according to the embodiments of the present invention will hereinafter be described in detail while referring to the accompanying drawings.

(21) In the following description, an overview of catheter treatment using an embolic coil will first be described based on FIG. 1. Next, a specific configuration of the embolic coil according to the first embodiment of the present invention will be described based on FIG. 2 and FIG. 3 and thereafter based on FIG. 4 and FIG. 5, the process for guiding an embolic coil into an aneurysm by using the embolic coil will be described.

(22) Next, a case where an embolic coil is guided into an irregularly shaped aneurysm will be described based on FIG. 6.

(23) Then, a specific configuration of the embolic coil according to the second embodiment of the present invention will be described based on FIG. 7 and FIG. 8, and thereafter based on FIG. 9 to FIG. 11, the process for guiding an embolic coil into an aneurysm by using the embolic coil will be described.

(24) Next, a case where the embolic coil is guided into an irregularly shaped aneurysm will be described based on FIG. 12 and FIG. 13.

(25) An example of the filling state of the embolic coil after completion of filling, according to the second embodiment, will be described based on FIG. 14. An example of the filling state of the embolic coil after completion of filling, according to the first embodiment, will be described based on FIG. 15.

(26) Further, the configuration of the embolic coil according to the third embodiment, fourth embodiment, and fifth embodiment of the present invention will be described based on FIG. 16 to FIG. 18 while focusing on the difference from the first embodiment. Finally, other embodiments having a different configuration from these embodiments will be mentioned.

First Embodiment (See FIG. 1 to FIG. 6)

(27) (1) Outline of Catheter Treatment that Utilizes an Embolic Coil (See FIG. 1)

(28) An embolic coil 1 is used in aneurysm treatment which employs a catheter 3 for the purpose of preventing rupture of an aneurysm A. Specifically, for example, when the aneurysm A develops at a bifurcation C of a cerebral artery B of a human body H, as shown in FIG. 1, an insertion opening F for inserting the catheter 3 into a crotch portion E is created, and the catheter 3 with a diameter of about 2 mm, for example, is inserted from a femoral artery of the crotch portion E.

(29) Further, a contrast agent is injected into a blood vessel, and the catheter 3 is guided to a position slightly deeper inside the aneurysm A at the site where the aneurysm A is developing while observing a fluoroscopic image obtained by X-rays. The embolic coil 1 of the present invention is then inserted into the catheter 3, and guided to a distal end of the catheter 3 along an inner wall of the catheter 3. A distal end portion of the embolic coil 1 is extruded from an opening of the distal end and guided into the aneurysm A. Thereafter, the embolic coil 1 is pushed outwards, and guided and filled into the aneurysm A.

(30) Though the aneurysm sometimes takes other forms such as a saccular aneurysm and a dissecting aneurysm developed in non-bifurcated areas other than the bifurcation C, these types of aneurysms can also be treated with the embolic coil 1.

(31) (2) Specific Configuration of the Embolic Coil (See FIG. 2 and FIG. 3)

(32) The embolic coil 1 of the present embodiment is formed by spirally winding a wire 2 and basically includes: a first coil portion 5, in which a large-diameter coil portion 7 wound to have a maximum outer diameter of D1 and a small-diameter coil portion 9 wound to have a diameter D2 smaller than the large-diameter coil portion 7 are alternately provided in a plurality in the longitudinal direction Y of the embolic coil 1; and a second coil portion 15 wound to be continuous from the first coil portion 5 and to have a surface flatter than the first coil portion 5.

(33) The first coil portion 5 has a convex-concave structure on its surface due to the arrangement of a plurality of the alternately provided large-diameter coil portions 7 and the small-diameter coil portions 9. In the present embodiment, the second coil portion 15 has a cylindrical structure with a flat surface, in which the wire is wound to maintain a uniform diameter D3. Here, the “large diameter” of the large-diameter coil portion 7 may have a width that is uniform along the entire length in the axial direction (longitudinal direction Y of the embolic coil 1) of the large diameter coil portion 7, but preferably as shown in FIG. 2 has a structure, in which the maximum outer diameter portion is provided in the center and the diameter is gradually reduced symmetrically in the axial direction.

(34) The embolic coil 1A according to the present embodiment has a structure in which the first coil portion 5 with a predetermined length L1 and the second coil portion 15 with a predetermined length L2 are repeatedly provided in the longitudinal direction.

(35) The ratio of presence of the first coil portion 5 and the second coil portion 15 is appropriately set relative to the size and shape of the aneurysm, but here as shown in FIG. 3, there are plural sets of the first coil portion 5 and the second coil portion 15 in a frame 23 formed in the aneurysm A. In FIG. 3, the predetermined length L1 of the first coil portion 5 is formed larger than the predetermined length L2 of the second coil portion 15 so that L1>L2, but the present invention is not limited thereto. The relationship between L1 and L2 may be reversed, or L1 and L2 may have the same length.

(36) In the example of the present embodiment shown in FIG. 2, an outer surface of the large diameter coil portion 7 constituting a part of the first coil portion 5 is formed in the shape of spherical convex curved surface 17. The small diameter coil portion 9 constituting another portion of the first coil portion 5 is formed as an example in a cylindrical shape linearly extending in the longitudinal direction Y.

(37) On the other hand, the second coil portion 15 is formed for example with the same outer diameter D3 as the maximum outer diameter D1 of the large-diameter coil portion 7 of the first coil portion 5, and has a cylindrical structure linearly extending in the longitudinal direction Y.

(38) In the structure shown in FIG. 2 and FIG. 3, a connected portion between the second coil portion 15 and the first coil portion 5 continues to the small diameter coil portion 9, so that a step is formed at a boundary portion therebetween by the diameter D2 and the diameter D3. The step can be eliminated by making the connected portion of the second coil portion 15 continue to a portion of the maximum outer diameter D1 of the large diameter coil portion 7.

(39) As a material of the embolic coil 1A configured in this way, a wire (shown as wire 2), having a wire diameter d of 15 μm to 100 μm, preferably 30 μm to 75 μm, and made from platinum, tungsten, or stainless steel can for example be used. Since these materials are resistant to corrosion and combine appropriate rectilinearity and flexibility, when the embolic coil 1A moves inside the catheter 3, the embolic coil 1A moves smoothly while maintaining appropriate rectilinearity, and when the coil 1A is guided into the aneurysm 1A, this flexibility functions to make the coil 1A curve smoothly and fill the aneurysm A.

(40) As the outer diameter D2 of the small-diameter coil portion 9 of the first coil portion 5, 0.06 mm to 0.40 mm, preferably 0.12 mm to 0.30 mm can be adopted. The maximum outer diameter D1 of the first coil portion 5 and the outer diameter D3 of the second coil portion 15 should be larger than the outer diameter D2 of the small diameter coil portion 9 and should allow smooth movement in the catheter 3, and can be set for example, 0.2 mm to 0.5 mm, preferably 0.25 mm to 0.47 mm.

(41) FIG. 2 shows the embolic coil 1A in a primary shape when moving inside the catheter 3. However, as shown in FIG. 3, the embolic coil 1A of a secondary shape having a larger coil diameter (for example, 3 mm to 30 mm) may be formed in advance so that the frame 23 is formed more easily to match the size and shape of the aneurysm A. The formation of the secondary shape may be omitted. The embolic coil 1A of the present embodiment is confirmed as capable of smoothly forming the frame 23 without forming a secondary shape.

(42) (3) Step of Guiding the Embolic Coil (See FIG. 4 to FIG. 5)

(43) Next, the process of guiding the embolic coil 1A into the aneurysm A using the embolic coil 1A according to the present embodiment is described in two stages: (A) immediately before the start of coil guiding, and (B) frame formation.

(44) (A) Immediately Before the Start of Coil Guiding (See FIG. 4)

(45) When guiding the embolic coil 1A, as described above in the aforementioned (1) Outline of catheter treatment that utilizes an embolic coil, as a preparation work, the catheter 3 is placed in the human body H and the distal end of the catheter 3 is guided to reach the inside of the aneurysm A. Next, the distal end Y1 of the embolic coil 1A in the longitudinal direction Y is inserted into the catheter 3 placed in the human body H from outside, and the embolic coil 1A is moved toward the aneurysm A along the inner wall surface of the catheter 3.

(46) At this time, the embolic coil 1A can be inserted smoothly into the catheter 3, since in the embolic coil 1A according to the present embodiment, the large diameter coil portion 7 of the first coil portion 5 to be inserted first is formed by the spherical convex curved surface 17. In addition, the rectilinearity of the embolic coil 1A in the catheter 3 can be maintained, since the outer diameter of the large-diameter coil portion 7 of the first coil portion 5 of the embolic coil 1A and the outer diameter of the second coil portion 15 according to the present embodiment are the same, so that the outer peripheries thereof function as a guide. The above described arrangement therefore allows moving the embolic coil 1A smoothly. The distal end Y1 of the embolic coil 1A is then protruded from the distal end opening of the catheter 3 and brought into the aforementioned aneurysm A, and thereby the preparatory work prior to the guiding of the embolic coil 1A is completed.

(47) (B) Frame Formation (See FIG. 5)

(48) After completion of the preparatory work, the operation of guiding the embolic coil 1A is performed to advance the embolic coil 1A into the catheter 3. The embolic coil 1A delivered from the distal end opening of the catheter 3 is guided deeper into the aneurysm A, and the distal end Y1 of the embolic coil 1A first contacts the inner wall surface on the deeper side of the aneurysm A, and bends along the inner wall surface, and then goes out toward the front or the side.

(49) The distal end portion of the embolic coil 1A is then fed out toward the front or the side and brought into contact with the inner surface of the aneurysm A of the relevant portion and is further folded back while being bent to form a ring-shaped portion 21.

(50) Further, as the guiding of the embolic coil 1A progresses, a plurality of ring-shaped portions 21 are formed as shown in FIG. 5. These ring-shaped portions 21 form the frame 23, which serves as an outer shell member during guiding of the subsequent embolic coil 1A. Here, it is preferable that the amount of the first coil portion 5 and the second coil portion 15 in the plurality of ring-shaped portions 21 forming the frame 23 is appropriately set and used to match the size and shape of the aneurysm.

(51) As described above, in the embolic coil 1A according to the present embodiment, when the embolic coil 1A is guided into the aneurysm A and when several ring-shaped portions 21, in a state curved into a ring shape in the aneurysm A, are produced to form the frame 23, even if the quantity of the ring-shaped portions 21 increases along with the progress of the formation of the frame 23 due to the presence of the flat cylindrical structure (second coil portion 15) portion, the possibility of catching is reduced. Therefore, in the embolic coil 1A according to the present embodiment, when forming the frame 23 in the aneurysm A, the frame 23 can be smoothly formed without catching.

(52) Further, in the frame 23, at the stage when the frame 23 is formed, at a contact position (intersecting position) between the ring-shaped portions 21, a spot where the large-diameter coil portion 7 is caught is created due to the presence of the convex-concave structure (first coil portion 5). As a result, an anchor effect due to catching of the large-diameter coil portion 7 is produced, and the structure of the frame 23, that is, the three-dimensional structure by the plurality of ring-shaped portions 21 is therefore stabilized.

(53) <In relation to Expansion and Deformation of Aneurysm Volume>

(54) As the introduction of the embolic coil 1A progresses while the large diameter coil portion 7 is being caught, the volume of the aneurysm A expands and deforms more as the introduction of the embolic coil 1A progresses than at the beginning of introduction. In the present embodiment, since the flat cylindrical structure (second coil portion 15) portion is present at a constituent portion of the structure of the frame 23, when the volume of the aneurysm expands and deforms, the position where the large diameter coil portion 7 is caught can be moved along the cylindrical structure portion.

(55) Here, the cylindrical structure (second coil portion 15) portion of the embolic coil 1A has a larger repulsive force to the curve and deformation than the convex-concave structure (first coil portion 5) portion. Due to the repulsive force of the cylindrical structure portion, the force for expanding the frame 23 outward is stronger than conventional embolic coils which only have a convex-concave structure. This repulsive force moves the position where the large diameter coil portion 7 becomes caught, in a direction that expands the frame 23 along the cylindrical structure portion. In other words, the frame 23 can become larger to match the expansion and deformation of the volume of the aneurysm A. Thereby, it is possible to reduce the possibility that the position of the frame 23 becomes unstable in the expanded and deformed aneurysm A. The ring-shaped portion 21 is positioned along the inner surface of the enlarged and deformed aneurysm A, and the frame 23 can be held firmly in the aneurysm A.

(56) Further, in the present embodiment, the cylindrical structure portion is repeatedly present in the constituent portion of the structure of the frame 23. It is a state in which portions, which have a large repulsive force to the curve and deformation, repeatedly exist in the constituent portion of the structure of the frame 23. The frame 23 can in this way become larger even more effectively following the expansion and deformation of the volume of the aneurysm A.

(57) In this embodiment, since the secondary shape for forming the frame is further formed at the distal end portion of the embolic coil 1A, an elastic force for returning to the secondary shape acts so that the ring-shaped portion 21 is more smoothly formed.

(58) Even if the secondary shape is not formed, the embolic coil 1A itself receives a curving force along the inner surface of the aneurysm A within the aneurysm A, and an outward expanding force is generated by the repulsive force of the embolic coil that received the curving force. Due to this force, the ring shaped portion 21 is positioned and held along the inner surface of the aneurysm A. In other words, the ring-shaped portion 23 is easily formed even if no secondary shape is formed.

(59) (4) When Filling an Embolic Coil into an Irregularly Shaped Aneurysm (See FIG. 6)

(60) Next, descriptions will be made on the process of guiding the embolic coil 1A, in the case where a void region 29 is formed between the outer surface of the frame 23 formed in the aneurysm A and the inner surface of the aneurysm because of the irregularly shaped aneurysm A as shown in FIG. 6.

(61) If the aneurysm A is irregularly shaped, the void region 29 as shown may be formed between the outer surface of the frame 23 formed by the ring-shaped portion 21 and the inner surface of the aneurysm A.

(62) In this embodiment, even in such a case, since the cylindrical structure (second coil portion 15) portion allows smooth guidance with minimal catching, the cylindrical structure (second coil portion 15) portion can reach the void region 29 through a clearance 25 of the ring-shaped portion 21 of the frame 23 during its formation process.

(63) As described above, the cylindrical structure (second coil portion 15) portion can smoothly spread to the void region 29 and an inner space 27 of the frame 23 through the clearance 25 of the ring-shaped portion 21. The cylindrical structure (second coil portion 15) is therefore guided not only into the inner space 27 of the frame 23 but also into the void region 29 so as to fill both the inner space 27 and the void region 29.

(64) According to the present embodiment, when the frame 23 is formed, due to the presence of the cylindrical structure (second coil portion 15), the cylindrical structure (second coil portion 15) can protrude from the inside of the frame 23 to the outside with little resistance, through the clearance 25 of the ring-shaped portion 21 forming the frame 23. Therefore, even in the case where the shape of the aneurysm A is irregular and the void region 29 is likely to form between the outer side of the frame 23 and the inner surface of the aneurysm A, the cylindrical structure (second coil portion 15) can easily enter to the void region 29 by protruding outwards from the frame 23. The frame 23 can therefore be formed not only for a regularly shaped aneurysm but also for an irregularly shaped aneurysm.

Second Embodiment (See FIG. 7 to FIG. 12)

(65) (1) Specific Configuration of the Embolic Coil (See FIG. 7 and FIG. 8)

(66) An embolic coil 1B according to the second embodiment differs from the embolic coil 1A of the first embodiment in that instead of a repeating structure of the first coil portion 5 and the second coil portion 15 of the embolic coil 1A, the first coil portion 5 is located in the distal end of the embolic coil 1B and all the remaining portions of the embolic coil 1B connected to the first coil portion 5 are constituted by the second coil portion 15.

(67) In the embolic coil 1B according to the present embodiment, a single first coil portion 5 with a predetermined length L1 is arranged on the Y1 side distal end of the embolic coil 1B in the longitudinal direction Y, and one second coil portion 15 with a predetermined length L2 is likewise arranged at a portion from a terminal end of the first coil portion 5 to a terminal end Y2 of the embolic coil 1B in the longitudinal direction Y.

(68) Preferably, the “predetermined length L1” in “the first coil portion 5 with a predetermined length L1” is set in consideration of a length assumed as the portion constituting the frame 23 described later. Preferably, the second coil portion 15 is also partly included in the portion constituting the frame 23.

(69) FIG. 7 shows the embolic coil 1B in the primary shape during movement inside the catheter 3. However, as shown in FIG. 8, the embolic coil 1B of a secondary shape having a larger coil diameter (for example, 3 mm to 30 mm) may be formed in advance so that the frame 23 is more easily formed to match the size and shape of the aneurysm A. The formation of the secondary shape may be omitted in the same way as the first embodiment.

(70) Since the specific configurations of the first coil portion 5 and the second coil portion 15 of the embolic coil 1B are the same as the embolic coil 1A according to the above-described first embodiment, a detailed description thereof is omitted.

(71) (2) Step for Guiding the Embolic Coil (See FIG. 9 to FIG. 11)

(72) A process for guiding the embolic coil 1B into the aneurysm A using the embolic coil 1B according to the present embodiment is next described while grouped into the following three stages: (A) immediately before the start of guiding, (B) start of frame formation, (C) a state in which guiding the embolic coil proceeds even further after frame formation.

(73) (A) Immediately Before the Start of Guiding (See FIG. 9)

(74) The distal end Y1 of the embolic coil 1B in the longitudinal direction Y is inserted into the catheter 3 from the outside, and the embolic coil 1B is moved toward the aneurysm A along the inner wall surface of the catheter 3.

(75) At this time, in the embolic coil 1B according to the present embodiment, the first coil portion 5 is positioned at the distal end, and the remaining part of the embolic coil 1B connected to the first coil portion 5 is constituted by the second coil portion 15. The outer periphery of the second coil portion 15 effectively serves as a guide when advancing in the catheter 3, and the rectilinearity of the embolic coil 1B in the catheter 3 can be even further enhanced.

(76) (B) Frame Formation (See FIG. 10)

(77) The embolic coil 1B fed from the distal end opening of the catheter 3 is guided deeper into the aneurysm A, and the distal end Y1 of the embolic coil 1B first contacts the inner wall surface on the deeper side of the aneurysm A, and bends along the inner wall surface, and then goes out toward the front or the side.

(78) The distal end portion of the embolic coil 1B fed out toward the front or the side is then brought into contact with the inner surface of the aneurysm A at the relevant portion and is further folded back while being bent to form a ring-shaped portion 21.

(79) Further, as guiding of the embolic coil 1B progresses, as shown in FIG. 10, a plurality of ring-shaped portions 21 are formed. The frame 23 functions as an outer shell member by way of these ring-shaped portions 21 during guiding of the follow-up embolic coil 1B. As shown in FIG. 10, the present embodiment differs from the first embodiment in that the frame 23 is initially formed only with the convex-concave structure (first coil portion 5). However, in the stage shown in FIG. 10, the amount of the ring-shaped portion 21 in the aneurysm A is small so there is little possibility that the guiding operation will be obstructed by catching of the large-diameter coil portion 7.

(80) Furthermore, in this embodiment, since the secondary shape shown in FIG. 8 is formed at the first coil portion 5 of the embolic coil 1B, an elastic force for returning to the secondary shape acts so that the ring-shaped portion 21 is more smoothly formed.

(81) Even if the secondary shape is not formed, the embolic coil 1B itself receives a curving force along the inner surface of the aneurysm A within the aneurysm A, and a force for expanding outward is generated by the repulsive force of the embolic coil that received the curving force. Due to this force, the ring shaped portion 21 is positioned and held along the inner surface of the aneurysm A. The ring-shaped portion is in this way easily formed even if no secondary shape is formed.

(82) Then, at the intersecting position between ring-shaped portions 21 forming the frame 23, a locking effect (anchor effect) is exerted by the convex-concave structure of the first coil portion 5, so that the frame 23 is smoothly formed in a stable state with no possibility of becoming unhooked.

(83) (C) Guiding of the Second Coil Portion (See FIG. 11)

(84) When guiding of the first coil portion 5 is complete, the guiding of the subsequent second coil portion 15 starts. Since the outer diameter D3 of the second coil portion 15 has a uniform cylindrical shape with little convexity and concavity, smooth guidance is performed with minimal catching. As shown in FIG. 11, the clearance 25 of the ring-shaped portion 21 of the frame 23 and the inner space 27 of the frame 23 are densely filled to complete the frame 23.

(85) After completion of the frame 23, the subsequent second coil portion 15 encounters little resistance and can push open a small clearance via the portion of the previously guided embolic coil 1B to enter every corner in the aneurysm A. The filling ratio can thereby be improved.

(86) In the second embodiment, when a required amount of the embolic coil 1B is guided and filled into the aneurysm A, an appropriate position on the second coil portion 15 of the embolic coil 1B is cut by using an appropriate separating mechanism etc. (not shown). After cutting, the remaining embolic coil 1B, which was not used for filling, and the catheter 3 are pulled out and removed from the human body H.

(87) In the aneurysm A filled with the embolic coil 1B, an inflow of blood flowing in the blood vessel is suppressed by the presence of the embolic coil 1B, and a thrombus is positively formed and solidified in the aneurysm A, so that rupture of the aneurysm A is suppressed.

(88) Incidentally, the above cutting process can of course be rendered unnecessary by preparing in advance a length of the embolic coil 1B sufficient for forming the frame 23, and after the frame 23 is formed, guiding another embolic coil which is separate from the embolic coil 1B into the frame 23 so as to have a length necessary for forming the frame 23.

(89) As described above, according to the embolic coil 1B of the present embodiment, when the embolic coil 1B is guided into the aneurysm A and several ring-shaped portions 21, in a state of being curved in a ring shape in the aneurysm A are produced to form the frame 23, the possibility of the large-diameter coil portion 7 catching is reduced because of the presence of the flat cylindrical structure (second coil portion 15) portion. Therefore, according to the embolic coil 1B of the present embodiment, when forming the frame 23 in the aneurysm A, the formation of the frame 23 can be smoothly performed without catching.

(90) Further, in the frame 23, at the stage where the frame 23 is formed, at a contact position (intersecting position) between the ring-shaped portions 21, a place where the large-diameter coil portion 7 is caught is created because of the presence of the convex-concave structure (first coil portion 5). As a result, an anchor effect due to catching of the large-diameter coil portion 7 is produced, and thereby the structure of the frame 23 or namely the three-dimensional structure due to the plurality of ring-shaped portions 21 is stabilized.

(91) <Expansion and Deformation of the Aneurysm Volume>

(92) Since the guiding of the embolic coil 1A progresses further while the large diameter coil portion 7 is caught, the volume of the aneurysm A expands and deforms more as the guiding of the embolic coil 1A progresses than at the beginning of guiding. According to the present embodiment, since the flat cylindrical structure (second coil portion 15) portion is in the portion forming the structure of the frame 23, when the volume of the aneurysm is expanded and deformed, the position where the large diameter coil portion 7 is caught can be moved along the cylindrical structure portion.

(93) Due to a large repulsive force of the cylindrical structure (second coil portion 15) portion in the embolic coil 1B, the force for expanding the frame 23 outward is stronger than conventional embolic coils which only have the convex-concave structure. Due to this repulsive force, the position where the large diameter coil portion 7 is caught is moved in a direction for expanding the frame 23 along the cylindrical structure portion. In other words, the frame 23 can grow larger to follow up on the expansion and deformation of the volume of the aneurysm A. Therefore, the concern that the position of the frame 23 will become unstable in the expanded and deformed aneurysm A can in this way be reduced. The ring-shaped portion 21 is positioned along the inner surface of the enlarged and deformed aneurysm A, and the frame 23 can be held firmly in the aneurysm A.

(94) (3) When Filling an Embolic Coil into an Irregularly Shaped Aneurysm (See FIG. 12 and FIG. 13)

(95) Next, the process for guiding the embolic coil portion 1B will be described for the case as shown in FIG. 12 when the void region 29 is formed between the outer surface of the frame 23 formed in the aneurysm A and the inner surface of the aneurysm A since the aneurysm A is irregular.

(96) In this embodiment, since the cylindrical structure (second coil portion 15) portion allows smooth guidance with minimal catching, the cylindrical structure (second coil portion 15) portion can reach the void region 29 through the clearance 25 of the ring-shaped portion 21 of the frame 23 during its formation process (FIG. 13).

(97) As described above, the cylindrical structure (second coil portion 15) portion can smoothly spread to the void region 29 and an inner space 27 of the frame 23 by way of the clearance 25 of the ring-shaped portion 21. The cylindrical structure (second coil portion 15) is in this way guided not only into the inner space 27 of the frame 23 but also into the void region 29 to fill both of the inner space 27 and the void region 29.

(98) According to the present embodiment, when the frame 23 is formed, due to the presence of the cylindrical structure (second coil portion 15), the cylindrical structure (second coil portion 15) portion can protrude outwards from the inside of the frame 23 to the outside with little resistance, through the clearance 25 of the ring-shaped portion 21 forming the frame 23. Therefore, even in the case where the shape of the aneurysm A is irregular and the void region 29 is likely to form between the outer side of the frame 23 and the inner surface of the aneurysm A, the cylindrical structure (second coil portion 15) can easily enter to the void region 29 by sticking out from the frame 23. Therefore, the frame 23 can easily be formed not only for regularly shaped aneurysms but also for irregularly shaped aneurysms.

(99) FIG. 14 is a simplified schematic view showing a filled state of an aneurysm, in which the embolic coil 1B according to the present embodiment was filled into the aneurysm as shown in FIG. 10, and the subsequent second coil portion 15 was guided, and then filling was completed.

(100) A primary filled layer 31, which is mainly formed by the first coil portion 5 by filling this first coil portion 5, is formed in an outer region near the inner surface of the aneurysm A. And a secondary filled layer 33, which is formed by filling the second coil portion 15, is formed in a region inside the primary filled layer.

(101) Incidentally, FIG. 14 is a simplified illustration allowing an easier understanding of the state in which the embolic coil 1B is filled into the aneurysm A. Usually, the primary filled layer 31 and the secondary filled layer 33 are seldom divided into such a simple layer arrangement. Since the guidance of the embolic coil 1B advances further to the clearance portion in the state shown in FIG. 10, a region where the embolic coil 1B is present as well as the boundary between the two layers 31, 33 are complex. In other words, FIG. 14 explains that the primary filled layer 31 and the secondary filled layer 33 generally tend to be formed in layer shapes.

(102) In this way, when the secondary filled layer 33 located on the inner side is constituted by filling the cylindrical structure (second coil portion 15), a strong repulsive force against the curve and deformation of the cylindrical structure (of the second coil portion 15) is obtained. The frame 23 can therefore more effectively follow up on the expansion and deformation of the aneurysm volume and become larger.

(103) FIG. 15 is a view schematically showing a filled state of the aneurysm, in which guiding of the embolic coil 1A with a repeating structure starts, the guiding continues, and filling is completed. Here, a length of the first coil portion 5 in the embolic coil 1A according to the first embodiment is made long enough to form the frame 23 just by the first coil portion 5, and a length of the second coil portion 15 is made about the same as the first coil portion 5.

(104) The primary filled layer 31 is mainly formed in the region on the outer side near the inner surface of the aneurysm A, and the secondary filled layer 33 is mainly formed in the region inside the primary filled layer 31. Here, the amount of the primary filled layer 31 corresponds to the length of the first coil portion 5 located in a distal end formed by filling the first coil portion of the distal end, and the secondary filled layer 33 is formed by filling the second coil portion 15 that is subsequent to the first coil portion 5 located in the distal end. Next, the primary filled layer 31 with the amount corresponding to the length of the first coil portion 5 in the second order is mainly formed. And the secondary filled layer 33, which is formed by filling the second coil portion 15 in the second order following the first coil portion 5, is mainly formed in the region inside the primary filled layer 31.

(105) Incidentally, FIG. 15 is a simplified illustration to allow an easier understanding of the state in which the embolic coil 1A is filled into the aneurysm A. Under actual circumstances, the primary filled layer 31 and the secondary filled layer 33 are seldom divided into such a simple layer structure. The region where the embolic coil 1A is present as well as the boundary between the two layers 31, 33 are complex. In other words, FIG. 15 explains that the primary filled layer 31 and the secondary filled layer 33 generally tend to be formed in layer shapes.

(106) In this way, a filled state of the embolic coil 1B having a multiple layer structure in which the primary filled layer 31 and the secondary filled layer 33 generally tend to repeat is formed within the aneurysm A. The filled state of the embolic coil 1B, which is more stable and which has a higher filling ratio can thus be obtained.

Third Embodiment (See FIG. 16)

(107) In the embolic coil 1C according to the third embodiment, the order of the first coil portion 5 and the second coil portion 15 according to the above-described first embodiment is reversed so that the second coil portion 15 on the distal end Y1 side of the embolic coil 1C in the longitudinal direction Y, and the first coil portion 5 are arranged behind the second coil portion 15, and thereafter the second coil portion 15 and the first coil portion 5 are repeatedly arranged in this order toward the terminal end Y2 of the embolic coil 1C in the longitudinal direction.

(108) Since the specific configurations of the first coil portion 5 and the second coil portion 15 of the embolic coil 1C are the same as the configuration of the embolic coil 1A according to the first embodiment and the embolic coil 1B according to the second embodiment, described above, a detailed description thereof is omitted.

(109) According to the present embodiment, the catching by itself like the first coil portion 5 cannot be expected because the furthest distal end is the second coil portion 15, however, the substantially same effect can be obtained in other respects.

Fourth Embodiment (See FIG. 17)

(110) The embolic coil 1D according to the fourth embodiment is different from the embolic coil 1B according to the second embodiment in that the shape of the spherical large-diameter coil portion 7 in the first coil portion 5 of the embolic coil 1B according to the second embodiment is a convex shape like the bead of an abacus in which the bottom surfaces of two triangular pyramids are joined together.

(111) Since the specific configurations of the small-diameter coil portion 9 of the first coil portion 5 and the second coil portion 15, in the embolic coil 1C, are the same as the configuration of the embolic coil 1A according to the first embodiment and the embolic coil 1B according to the second embodiment described above, a detailed description thereof is omitted.

(112) With the embolic coil 1D according to the present embodiment configured in this way, the same functions and effects as those of the embolic coil 1B according to the second embodiment are exhibited.

Fifth Embodiment (See FIG. 18)

(113) In the embolic coil 1E according to the fifth embodiment, the shape of the small diameter coil portion 15, which is uniformly in a cylindrical shape in the longitudinal direction Y of the first coil portion 5 of the embolic coil 1B according to the second embodiment described above, is changed, and the concave curved surfaces 19 in the spherical shape are formed on the outer surface of the small-diameter coil portion 15.

(114) Since the specific configurations of the large-diameter coil portion 7 of the first coil portion 5 and the specific configurations of the second coil portion 15, in the embolic coil 1E, are the same as those of the embolic coil 1B according to the second embodiment described above, a detailed description thereof is omitted.

(115) The embolic coil 1E according to the present embodiment configured in this way also exhibits the same functions and effects as the embolic coil 1B according to the second embodiment described above. Further, compared to the cylindrical small diameter portion 9 wound with the uniform diameter adopted in the second embodiment; in this embodiment, due to the spherical concave curved surface 19 formed on the outer surface of the coil portion 9, the sliding resistance of the embolic coil 1E is reduced to allow smooth guiding of the embolic coil 1E with little possibility of the large diameter coil portion 7 catching. Easier bending is also achieved compared to the embodiment having a uniform diameter D2.

Other Embodiments

(116) The embolic coil 1 according to the present invention is generally based on the configuration as described above, but of course changing or omitting a portion of the configuration within a scope not deviating from the essentials of the present invention is permissible.

(117) For example, the lengths of the large-diameter coil portion 7 and the small-diameter coil portion 9, which are alternately arranged, can be appropriately adjusted depending on the wire diameter d of the wire 2, and the size and shape of the aneurysm A, etc.

(118) Further, the shape of the large diameter coil portion 7 is not limited to the spherical shape and the abacus bead shape described in the above embodiments, but may be formed in other shapes such as a streamline shape or a cylindrical shape.

(119) Further, in the above-described repetitive structure, the length L1 of the first coil portion 5 and the length L2 of the second coil portion 15 are described such that the same L1 and the same L2 are repeated. However, all of the L1 need not be the same, and all of the L2 need not be the same and may be different.

(120) In addition, the concave curved surface 19 in the fifth embodiment is provided over the entire length of the small-diameter coil portion 9. However, the concave surface 19 may be partially provided such as at a boundary portion with the large-diameter coil portion 7. Also, the concave curved surface 19 is not limited to a spherical shape in the same way as the convex curved surface 17 applied to the large diameter coil portion 7, but may be formed into various types of concave curved surfaces.

(121) In addition, the secondary shape formed at the distal end portion of the embolic coil portion may be omitted and an embolic coil may be formed in just a primary shape.

(122) The secondary shape may be formed only in the first coil portion 5 of the distal end portion, or only in the second coil portion 15 of the distal end portion. Or, the secondary shape may be formed in both of the coil portions 5 and 15.