JP6055163B2 - Stent - Google Patents

Description

  The present invention relates to a stent that is placed in a lumen of a human body to prevent obstruction in the lumen or breakage of the lumen.

  Stroke that suddenly develops suddenly among cerebrovascular disorders occurs mainly due to cerebrovascular occlusion and bleeding from the cerebral blood vessels.

  Among them, stroke caused by cerebrovascular obstruction occurs when an embolism (a blood clot, fat embolus, tumor embolism, etc.) enters a cerebral artery, constricts the artery, blocks blood flow, and causes cerebral ischemia. A disease that occurs, called cerebral infarction. When the blood flow to the brain is blocked by embolism, the brain cells are deprived of oxygen and nutrients and go to necrosis in a short time. For this reason, it is important to quickly ensure normal blood flow in the early stage of the onset of cerebral infarction. If normal blood flow is not secured at an early stage, the brain tissue loses its function and there is a high risk that the patient's life will be threatened.

  On the other hand, a stroke caused by bleeding from a cerebral blood vessel is classified into cerebral hemorrhage and subarachnoid hemorrhage according to the bleeding site. Among them, subarachnoid hemorrhage is mostly caused by rupture of a cerebral aneurysm formed in the cerebral artery wall. Aneurysms are prone to rupture because the vessel wall lacks the media, and subarachnoid hemorrhage is likely to recur once it occurs, so if an unruptured aneurysm is found, treatment to prevent rupture It is necessary to carefully judge whether or not

  Until now, when it is necessary to treat cerebrovascular obstruction or to treat aneurysms formed in the cerebral blood vessels as described above, many methods have been adopted for direct surgery of the cerebral blood vessels by craniotomy or neck incision. . On the other hand, in recent years, non-invasive techniques with less physical burden on patients have attracted attention due to advances in endovascular treatment techniques. Stent placement is one of the well-known techniques.

  Stent placement is a technique in which a fine tube called a stent is placed in a lumen such as a blood vessel to widen a constricted site or prevent aneurysm from rupturing. Generally, in stent placement, a catheter is inserted from a blood vessel (femoral artery) or the like at the base of a foot under local anesthesia, and the stent is transported and placed through a lesion site where an aneurysm or stenosis has occurred.

  FIG. 10 shows an example of a stent used in conventional stent placement. The conventional stent 100 is usually formed by knitting a metal wire into a cylindrical shape as shown in FIG. 10A and cutting it into an appropriate size. And the resin coating etc. are made | formed to the surrounding surface as needed.

  Since the wire constituting the stent 100 is very thin and flexible, and has elasticity, the stent 100 is easily deformed and returned to its original state by elasticity. Therefore, when a force is applied from the outer periphery toward the central axis of the stent 100, the stent 100 extends in the axial direction while reducing the diameter, as shown in FIG. Therefore, the stent 100 is stored in a stretched and contracted state in a delivery catheter such as a stent introducer, and is delivered by following the guide wire to the lesioned part. When the lesion is reached, the stent 100 is released from the delivery catheter into the blood vessel. When released from the delivery catheter, the stent 100 is expanded by a restoring force, and is placed so as to fit the inner wall of the blood vessel of the lesion. By placing the stent 100 in the blood vessel in this way, it is possible to secure blood flow by expanding the stenosis and restrict blood flow to the aneurysm.

  However, the conventional stent 100 has the following problems.

  (1) When the stent 100 is transported to the lesioned part in a state where the stent 100 is greatly stretched in the axial direction, the contraction in the axial direction is increased when the stent is discharged from the transport catheter and unloaded, and the force at the time of deformation is intended. There was a case where it was displaced from the position of the lesion.

  (2) When the stretchability in the axial direction of the stent 100 is increased, the contractibility in the radial direction is increased accordingly, and thus there is a possibility that the stent 100 may move due to blood flow after the placement treatment.

  (3) When the blood vessel in which the stent 100 is installed contracts, in order to maintain a good blood flow, it is necessary that the expansion force in the radial direction of the stent 100 (resistance force against the contraction of the blood vessel) is large. In the stent 100, since the stretchability in the stent axial direction is too high, this resistance force was small.

  The present invention has been made in view of the above-mentioned problems of the prior art, and by restricting the stretchability in the stent axial direction, the shrinkability in the stent radial direction is kept low, and the expansion force in the stent radial direction is reduced. An object is to provide a stent that can be kept high.

  The present invention relates to a stent formed in a substantially tubular body that is used by being placed in a lumen such as a blood vessel of a human body, and is a first transverse device wired at an acute angle of 45 degrees or less with respect to the stent axis. A square mesh shape formed by a wire group and a second wire group in the vertical direction intersecting the first wire group, and woven by the first wire group and the second wire group, is formed in the cross-sectional direction of the stent axis. A first end at the periphery of one end of the stent and a second end at the periphery of the other end at a symmetrical position of the first end with respect to the stent axis. There is provided a stent characterized in that it has a shape extending in the opposite direction in the axial direction.

  As a result, the stent according to the present invention realizes that the expandability in the stent radial direction is kept high by limiting the stretchability in the stent axial direction and suppressing the contractibility in the stent radial direction low.

  Here, the extension ratio of the stent in the stent axial direction is adjusted by the angle of the first wire group with respect to the stent axis. The angle of the second wire group with respect to the stent axis is preferably 45 degrees or more.

  In the second wire group, the mesh at the center of the stent is densely formed with respect to the mesh at both ends. Thus, the blood flow pressure in the vascular affected part (for example, aneurysm) where the stent is disposed is received by the dense mesh in the central part, thereby preventing the vascular affected part from being ruptured.

  The first end and the second end may form a marker made of a metal material that is impermeable to X-rays.

  Furthermore, it is preferable that the first end portion forms a connection portion with an operation wire for moving the stent, and the connection with the operation wire is released by passing an electric current through the first end portion. Alternatively, the first end may be connected to the tip of the operation wire by a hook or screw, and the connection to the operation wire may be released by removing the hook or screw.

  The first wire group and the second wire group are formed of a plurality of elastic wire materials, and the wire materials are curved without bending at the one end and / or the other end of the stent. In a state of being bent in a shape, it is preferable that the shape is extended in the opposite direction in the stent axial direction. Alternatively, the wire material may be welded to each other in a cut state at the one end and the other end of the stent.

  The wire material is preferably a wire made of gold, platinum or tungsten, or a shape memory wire in which nickel or titanium is coated with gold or platinum.

  The shape memory wire is preferably coated with a collagen material into which plus helium ions are implanted. As a result, blood coagulation can be prevented and the rejection reaction can be suppressed.

  Furthermore, it is preferable that the outer diameter of the stent is 3 to 6 millimeters, and the stent is used by being placed in the cerebral blood vessel.

  According to the stent of the present invention, by restricting the stretchability in the stent axial direction, it is possible to keep the contractibility in the stent radial direction low and to maintain a high expansion force in the stent radial direction. As a result, the stent is correctly arranged without deviating from the intended lesion, and it is possible to maintain a good blood flow or restrict the blood flow to the aneurysm.

It is a schematic diagram which shows the outline of the external appearance of the stent which concerns on one Embodiment of this invention. It is a schematic perspective view of the stent shown in FIG. It is a mimetic diagram for explaining an angle of each wire group and a stent axis of a stent concerning one embodiment of the present invention. It is a schematic diagram which shows an example of the state of the lesioned part which uses the stent shown in FIG. FIG. 3 is a schematic diagram (part 1) illustrating an example of a method of using the stent illustrated in FIG. 1. FIG. 3 is a schematic diagram (part 2) illustrating an example of a method of using the stent illustrated in FIG. 1. It is a schematic diagram which shows an example in the case of applying the stent shown in FIG. 1 to a cerebral aneurysm. It is a schematic diagram (the 1) which shows the outline of the external appearance of the stent which concerns on other embodiment of this invention. It is a schematic diagram (the 2) which shows the outline of the external appearance of the stent which concerns on other embodiment of this invention. It is a schematic diagram which shows an example of the stent used by the conventional stent placement technique.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic diagram showing an outline of the appearance of a stent according to an embodiment of the present invention, FIG. 1 (a) is a front view thereof, and FIG. 1 (b) is an AA cross section of FIG. 1 (a). FIG. FIG. 2 is a schematic perspective view of the stent shown in FIG.

  As shown in these drawings, the stent 10 of the present invention is configured by knitting a plurality of wires 11 having a very thin and flexible shape and elasticity, into a cylindrical shape (tubular shape). The appearance of the stent 10 is a cylindrical shape that is obliquely cut as shown in FIG. 2, and it looks like a substantially parallelogram from the front as shown in FIG. Of the two end edges 12 and 13 of the stent 10, the position of the stent 10 is confirmed at one end (first end) 14 and the other end (second end) 15, respectively. A marker 31 for performing the above is disposed.

  The plurality of wires 11 constituting the stent 10 includes a first wire group 21 and a second wire group 22, and the first wire group 21 and the second wire group 22 intersect each other to form a rectangular shape. The stent 10 is formed by knitting to form a mesh. The mesh quadrilaterals formed by the wire groups 21 and 22 are substantially parallelograms and are asymmetric with respect to the cross-sectional direction of the central axis 41 of the stent 10 [stent axis; see FIG. 1 (a)].

  The wire 11 constituting the stent 10 is preferably a wire made of gold, platinum or tungsten, or a shape memory wire in which nickel or titanium is coated with gold or platinum.

  By the way, the wire 11 forming the stent 10 is a shape memory wire, and it is desirable to apply a collagen material into which plus helium ions are implanted. This makes it possible to prevent blood coagulation and suppress the rejection reaction.

  Here, as shown in FIG. 3A, the first wire group 21 forms an angle α (first angle) with respect to the central axis 41 of the stent 10. In the stent 10 of the present invention, the angle α is set to 45 degrees or less in order to limit the stretchability in the stent axial direction. Therefore, here, for convenience, the first wire group 21 is referred to as a lateral wire. The stretch ratio of the stent 10 can be easily adjusted by the angle α. For example, when the angle α is 45 degrees, √2 or less, and when the angle α is 30 degrees, 2 / √3 or less. As described above, in the present invention, the contractibility of the stent 10 in the radial direction is suppressed by limiting the stretchability of the stent 10. When the contractibility in the radial direction of the stent 10 is suppressed, the stent 10 becomes difficult to move even after the placement treatment.

  The second wire group 22 forms an angle β (second angle) with respect to the central axis 41 of the stent 10 as shown in FIG. And in the stent 10 of this invention, in order to improve the expandability of the radial direction of a stent, angle (beta) shall be 45 degree | times or more. Therefore, here, for convenience, the second wire group 22 is referred to as a longitudinal wire. Increasing the expandability of the stent in the radial direction can increase the resistance to blood vessel contraction.

  The markers 31 installed at the two extreme end portions 14 and 15 of the stent 10 are made of a metal material having radiopacity (for example, platinum, iridium, etc.). The position of the stent 10 can be confirmed.

  Hereinafter, an example of the method of using the above-described stent 10 of the present invention will be described. Here, the case where the present stent 10 is used for the narrowed portion 62 of the cerebral blood vessel 61 by the embolus 63 as shown in FIG. 4 will be described as an example.

(1) Expansion of stenosis part by balloon First, as shown to Fig.5 (a), the guide wire 71 is sent in the cerebral blood vessel 61 to the position beyond the stenosis part 62. FIG.

  Then, as shown in FIG. 5B, the guide wire 71 is fed into the cerebral blood vessel 61 through the balloon catheter 72 and moved to a position where the balloon portion 73 of the balloon catheter 72 reaches the stenosis portion 62.

  Next, as shown in FIG. 5C, air is sent to the balloon catheter 72 to inflate the balloon portion 73 and expand the constricted portion 62. Thereafter, the balloon catheter 72 is removed.

(2) Insertion of Delivery Catheter and Release of Stent Next, as shown in FIG. 6A, the guide wire 71 is fed through the delivery catheter 74 to the vicinity of the expanded stenosis 62 '. The delivery catheter 74 is thinner than the diameter of the cerebral blood vessel 61, and the stent 10 is inserted and stored in advance. The first end portion 14 of the stent 10 is provided with a marker 31 and is connected to an operation wire 75 by a hook. Next, after confirming the position of the stent 10 from the positions of the two markers 31 and positioning it relative to the stenosis 62 ', the delivery catheter 74 is retracted while holding the stent 10 with the operation wire 75, and the stent 10 is released. To do.

  Then, as shown in FIG. 6B, the stent 10 expands in the cerebral blood vessel 61 and covers the stenosis 62 '. Therefore, the operating wire 75 is operated to remove the hook from the stent 10, and the stent 10 is left in place as shown in FIG. Thereafter, the guide wire 71, the delivery catheter 74, and the operation wire 75 are pulled out from the body. As described above, blood flow in the stenosis 62 can be ensured.

  In addition, although the example which fixes the operation wire 75 and the 1st end part 14 of the stent 10 here with the hook was shown here, you may fix with a screw other than a hook. That is, a female screw portion and a male screw portion are formed at the first end portion 14 of the stent 10 and the tip of the operation wire 75, respectively, and when the operation wire 75 is removed from the stent 10, the operation wire 75 is rotated. Alternatively, the distal end of the operation wire 75 and the first end portion 14 of the stent 10 may be fixed with solder. When removing the operation wire 75 from the stent 10, current is passed through the operation wire 75 to dissolve the solder.

  In the above description, an example in which a stent is placed in a stenosis portion of a cerebral blood vessel due to embolism to secure blood flow has been described. However, the stent 10 of the present invention also restricts blood flow flowing into an aneurysm, thereby reducing an aneurysm. It can be similarly applied to stent placement for preventing rupture.

  FIG. 7 shows an application example to the aneurysm. In FIG. 7A, the aneurysm 82 generated in the cerebral artery 81 is filled with the coil 83, and the stent 10 is placed in the same manner as in FIGS. Thus, if the coil 83 is packed in the aneurysm 82 to restrict the blood flow, the aneurysm 82 becomes a thrombus and the aneurysm 82 can be prevented from rupturing. At this time, since the stent 10 covers the entrance of the aneurysm 82, it is possible to prevent the movement of the coil 83, prevent reopening of blood, etc., and reliably prevent the aneurysm 82 from rupturing.

  In FIG. 7B, the blood flow to the aneurysm 82 generated in the cerebral artery 81 is restricted using the covered stent 10A in which the inner and outer surfaces of the stent 10 are coated with a cover material such as a resin. That is, by coating the stent 10 to form the covered stent 10A, blood flowing from between the meshes of the wire 11 is reduced, and the aneurysm 82 is thrombosed without using the coil 83. Rupture can be prevented.

  As shown in FIG. 7B, in the present stent 10, the second wire group 22 is formed such that the mesh at the center of the stent 10 is dense with respect to the mesh at both ends. Thereby, the blood flow pressure in the blood vessel affected part 82 such as an aneurysm where the stent 10 is disposed is received in the dense mesh at the central part to prevent the blood vessel affected part 82 from being ruptured.

  In the above description, the plurality of wires 11 constituting the stent 10 are curved in a curved shape at the end edges 12 and 13. Thus, by rounding the wire 11 at the end edges 12 and 13, the risk of damaging the vascular intima is reduced.

  On the other hand, as shown in FIG. 8, it is good also as the stent 10B which welded the wire 11 mutually in the edge 12 and 13. As shown in FIG. Furthermore, in order to simplify the manufacturing process, as shown in FIG. 9, a stent 10 </ b> C in which end edges 12 and 13 are simply cut may be used.

  Up to this point, the stents 10, 10 B, and 10 C formed only with wires and the coated stent 10 A coated with a resin have been described as examples, but in addition, a drug coating (DES; drug eluting stent) is applied. You can also. DES is a stent coated with a drug that suppresses cell growth. The drug slowly elutes in the body, preventing excessive formation of the intima that occurs when the stent is placed and preventing vascular restenosis. It can be effectively prevented.

  Furthermore, although the above description has been made taking a cerebral blood vessel as an example, stent placement is not limited to a cerebral blood vessel, but can be applied to blood vessels in other parts as well as to the whole body lumen (eg, trachea, esophagus, duodenum, large intestine, biliary tract, etc.) Applicable. Therefore, the stent of the present invention can also be applied to the whole lumen of the human body with a size corresponding to the site to be treated. For example, when used by being placed in a cerebral blood vessel, the outer diameter of the stent 10 is optimally 3 to 6 mm, more preferably about 5 mm.

  By configuring as described above, according to the stent of the present invention, by restricting the stretchability in the stent axial direction, the contractibility in the stent radial direction is kept low, and the expansion force in the stent radial direction is increased. Can be maintained. As a result, the stent is correctly arranged without deviating from the intended lesion, and it is possible to maintain a good blood flow or restrict the blood flow to the aneurysm.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, Based on the meaning of this invention, various deformation | transformation are possible, These are excluded from the scope of the present invention. is not.

  The present invention relates to a stent that is placed in a lumen of a human body to prevent obstruction in the lumen or breakage of the lumen, and has industrial applicability.

DESCRIPTION OF SYMBOLS 10 Stent 10A Covered stent 10B Stent 10C Stent 11 Wire 12 End edge 13 End edge 14 First end 15 Second end 21 First wire group 22 Second wire group 31 Marker 41 Central axis 61 Brain blood vessel 62 Stenosis 62 'Expanded stenosis 63 Emboli 71 Guide wire 72 Balloon catheter 73 Balloon catheter 74 Delivery catheter 75 Operation wire 81 Cerebral artery 82 Aneurysm 83 Coil

Claims (6)

A stent used by being placed in a lumen such as a blood vessel of a human body,
A first wire group in which a plurality of elastic wire materials are wired at a first angle α with respect to the stent axis and spaced apart from each other in the stent axis direction; and a plurality of elastic wire materials at a second angle with respect to the stent axis β is composed of a second wire group separated from each other in the stent axial direction,
The first wire group and the second wire group are knitted into a cylindrical shape intersecting each other so as to form a square mesh shape,
The stent according to claim 1, wherein the first angle α and the second angle β satisfy 0 ° <α ≦ 45 ° and 45 ° ≦ β <90 ° . 2. The stent according to claim 1 , wherein the plurality of wire materials constituting the second wire group are arranged closer to the center of the stent than both ends along the stent axial direction. . The cylindrical shape has end edges that open obliquely with respect to the stent axis at one end and the other end in the stent axial direction, respectively, and the most distal first end of the one end edge and the other end edge of the second end portion of the cutting edge is, the stent of claim 1 or 2, characterized in that it is arranged on the opposite side in the radial direction across the stent axis each other. The stent according to claim 3 , wherein a marker made of a metal material impermeable to X-rays is provided at the first end and the second end. The wire material constituting the first wire group and the second wire group, to claim 4, characterized in that it is curved in a curve shape without bending at the other and the one end of the stent The described stent. The stent according to claim 4 , wherein the wire material constituting the first wire group and the second wire group is welded to each other at the one end and the other end of the stent.

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