JP2012020067A - Stent delivery catheter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stent delivery catheter capable of being used safely, and getting the optimum delivery load simply designed.SOLUTION: In the stent delivery catheter 69, a face directed to a lumen 12 is uneven on the inner layer 11N in an outer tube 19 by copying the shape of a metal raw wire of a reinforcing layer 11M of the outer tube 19.

Description

  The present invention relates to a stent delivery catheter for delivering a stent.

  Stents generally treat a variety of diseases caused by stenosis or occlusion of blood vessels or other in vivo lumens. Specifically, a stent is a medical device that is placed in order to expand a stenosis or occlusion site and maintain its lumen size.

  Examples of the stent include a coil type made of a single linear metal or polymer material, a type in which a metal tube is cut out by a laser, a type in which a linear member is assembled by welding with a laser, or There are types made by weaving multiple linear metals.

  These stents are expanded by a balloon mounted with the stent (balloon expandable type), and are expanded by removing members that suppress expansion from the outside (self-expandable). Type).

  For example, the self-expandable type is generally used in the vicinity of the distal end of an intravascular catheter and covered with a sheath or the like. More specifically, the catheter is advanced to the treatment site in the body lumen of the patient, the sheath or the like is removed at the treatment site, and the stent is placed by self-expansion along with this. In recent years, these stents have been frequently used for ureteral, bile duct, or lower limb arthroplasty.

  When a self-expandable stent is delivered to a target lesion, the stent is generally inserted into a delivery catheter (note that a delivery catheter equipped with a stent is referred to as a stent delivery catheter). The delivery catheter itself may be referred to as a stent delivery catheter).

  In the case of such insertion, the stent is contracted (crimped) to be equal to or smaller than the inner diameter of the outer tube of the delivery catheter. And such a stent is separated from an outer tube, and is arrange | positioned in a lesioned part after conveying to a lesioned part with a delivery catheter. More specifically, when the surgeon pulls the outer tube from the proximal side, the inner shaft in the outer tube pushes the stent out of the outer tube, and the stent is placed in the lesioned part.

  By the way, in the stent delivery catheter, since the outer tube and the stent are statically fixed, a large resistance is generated when the operator pulls the outer tube from the hand side (the operator has to wear the outer tube from the hand side). The force pulling the tube is called the discharge load).

  In the design of the stent delivery catheter, if the release load is designed to be excessively low, the stent may be pulled out of the outer tube due to resistance during delivery of the stent, and the stent may be placed at an unintended site.

  Conversely, if the release load is designed to be excessively high, the stent will not easily fall out of the outer tube during delivery of the stent, but after the distal end of the stent delivery catheter reaches the lesion site to be treated, the outer tube cannot be pulled, The stent cannot be placed.

  Therefore, as in Patent Document 1, a stent delivery catheter with a controlled release load has been developed. In the stent delivery catheter of Patent Document 1, the discharge load is adjusted by applying a hydrophilic coating to the inner wall surface of the outer tube.

Special table 2003-510134 gazette

  However, in the stent delivery catheter described in Patent Document 1, not only is it troublesome to coat the hydrophilic coating, but the stent comes into contact with the hydrophilic coating, so that the hydrophilic coating is peeled off, and the peeled coating is in the body. It can remain.

  The present invention has been made to solve the above problems. An object of the present invention is to provide a stent delivery catheter that can be used safely and can be easily designed with an optimum discharge load.

  The stent delivery catheter includes a hollow outer shaft and an inner shaft that is inserted into the hollow of the outer shaft, and attaches the stent to an inner wall surface that surrounds the hollow with the outer shaft. The outer tube included in the outer shaft is a multilayer tube including a first layer serving as an inner wall surface and a second layer covering the first layer. And a 2nd layer is a layer which has an unevenness | corrugation, and a 1st layer makes an inner wall surface rough by reflecting the uneven | corrugated shape of a 2nd layer.

  Note that the thickness of the first layer is preferably more than 10% and less than 100% with respect to the thickness of the second layer.

  In the outer tube, the first layer is preferably a resin layer, and the second layer is preferably a layer formed of a metal wire.

  Further, in the longitudinal direction of the outer tube, the distal end that is one of both ends of the cylindrical stent is aligned with the distal end that is one of both ends of the outer tube or is hidden by the outer tube. The distal end of the outer tube is separated from the distal end of the outer tube, and in the longitudinal direction of the outer tube, the distal end that is one of both ends of the inner tube of the inner shaft coincides with the distal end of the outer tube, or It is preferable to be separated from the distal end of the outer tube so as to be exposed from the outer tube.

  The stent is preferably made of a shape memory alloy containing nickel and titanium.

  The stent delivery catheter of the present invention can be used safely, and the optimum discharge load is easily designed.

These are explanatory drawings of a stent delivery catheter. FIG. 3 is a cross-sectional view of a stent delivery catheter. These are explanatory drawings of a stent delivery catheter. These are explanatory drawings of a stent delivery catheter. These are explanatory drawings of a stent delivery catheter. These are explanatory drawings of a stent delivery catheter. These are explanatory drawings of the apparatus used for evaluation with respect to a stent delivery catheter. These are explanatory drawings of a stent delivery catheter.

[Embodiment 1]
The following describes one embodiment with reference to the drawings. For convenience, hatching, member codes, and the like may be omitted, but in such a case, other drawings are referred to. In addition to the cross-sectional view, hatching may be added for convenience.

  FIG. 1 shows an example of a stent delivery catheter 69, and FIG. 2 shows a cross-sectional view of the stent delivery catheter 69 of FIG. 1 (a cross section intersecting (or perpendicular to) the length of the stent delivery catheter 69).

  The stent delivery catheter 69 is used for transporting the stent 39 to a lesioned portion (stenosis portion) of a blood vessel, and is elongated and flexible so that it can be inserted into a lumen (from the stent delivery catheter 69, The one from which the stent 39 is removed may be referred to as a delivery catheter or a stent delivery catheter).

  The stent delivery catheter 69 includes a stent 39, an outer shaft 19, and an inner shaft 29 (in other words, the stent delivery catheter 69 includes a stent 39 and a delivery catheter having the outer shaft 19 and the inner shaft 29. ).

  As shown in FIG. 6, the stent 39 is formed by an annular substantially corrugated component [annular element] 32 continuing in an axial direction as one direction, and the substantially corrugated component 32 is a strut 31 that extends. It is formed by connecting

  In the stent 39 as shown in FIG. 6, the outer diameter OD and the axial length LD are appropriately selected according to the inner diameter and length of the lesioned lumen, depending on the lumen to be treated. Different. For example, in the superficial femoral artery stent 39, the outer diameter OD is set to about 6.0 mm to 10.0 mm, and the axial length LD is set to about 30 mm to 200 mm.

  The stent 39 is formed, for example, by subjecting a nickel-titanium alloy pipe subjected to laser cutting to a heat treatment by expanding the diameter (in short, the stent 39 is a shape memory alloy containing nickel and titanium). Manufactured).

  The outer shaft 19 includes an outer tube 11 that houses the stent 39 in a reduced diameter state. The stent 39 is a self-expandable stent that expands and treats the stenosis of the blood vessel. When the restriction by the lumen [hollow] 12 of the outer tube 11 is released, the inner diameter of the stent 39 is set to the outer tube 11. The outer diameter is expanded beyond the outer diameter, and the outer diameter after the expansion is determined.

  In addition, the outer tube 11 is a member having flexibility enough to follow a lumen (blood vessel or the like) to be inserted, kink resistance, and tensile strength not to expand when the stent delivery catheter 69 is pulled during the procedure. Formed with.

  In addition, when the outer tube 11 is moved, the inner layer of the outer tube 11 reduces the movement resistance (sliding resistance) with the stent 39 in contact with the inner peripheral surface of the layer, and the outer tube 11 It has a smoothness so that it can be easily moved.

  From the viewpoint of satisfying the above characteristics, the outer tube 11 has an outer layer (outer layer tube) 11T and an inner layer (inner layer tube) 11N formed of a resin material, and a metal wire between the outer layer 11T and the inner layer 11N. This layer (reinforcing layer) is preferably formed of a three-layer resin-metal composite tube [multi-layer tube] in which 11M is embedded.

  The outer layer [third layer] 11T is a layer covering the reinforcing layer 11M. For example, polyethylene, fluororesin {polytetrafluoroethylene (PTFE), or tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA) Etc.}, polyamide, polyamide-based elastomer, polyurethane, polyester, or various elastic resin materials such as silicone.

  The reinforcing layer [second layer] 11M is a layer covered with the outer layer 11T, and is a layer formed (knitted) with a metal wire. Then, when the metal strand becomes a braided structure or a coil structure, the reinforcing layer 11M has irregularities caused by the metal strand and the gap between the metal strands (in short, the reinforcing layer 11M The line becomes convex and the gap between the metal strands becomes concave). The reinforcing layer 11M is preferably formed from one end to the other end in the length of the outer tube 11 (in the stent delivery catheter 69, the side closer to the operator's hand is the proximal end, The opposite side to the proximal end is referred to as the distal end).

  In addition, as a material of a metal strand, various metal materials, such as stainless steel, a nickel titanium (Ni-Ti) alloy, tungsten, gold | metal | money, or platinum, are mentioned, for example.

  The inner layer [first layer] 11N is a layer covered with the reinforcing layer 11M. For example, fluororesin {polytetrafluoroethylene (PTFE) or tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), etc. } Or a low friction material such as polyethylene.

  The outer tube 11 is not limited to a three-layer composite tube, and may be formed of a single-layer tube. As a material of such a single-layer outer tube 11, for example, a fluororesin {polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), etc.}, or polyethylene Such a low friction material is mentioned (however, the inner wall surface 11Nf of the outer tube 11 is a rough surface including irregularities as described later).

  The inner shaft 29 is accommodated in the lumen 12 of the outer shaft 19 and includes an inner tube 21, a pusher marker 23, a core wire 25, and a tip end 27.

  The inner tube 21 is a tube having a hollow (lumen 22; see FIG. 2; not shown in FIG. 1 for convenience), and at least a part of the inner tube 21 is inserted into the lumen 12 of the outer tube 11 of the outer shaft 19. A guide wire (not shown) is inserted into the lumen formed in the inner tube 21 to guide the outer shaft 19 to the lesioned part.

  The inner tube 21 has flexibility enough to follow the inserted lumen (lumen 12 of the outer tube 11), kink resistance, and tensile strength that does not extend when the catheter is pulled during the procedure. .

  For example, polyethylene, fluororesin {polytetrafluoroethylene (PTFE) or tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), etc.}, polyamide, polyamide elastomer, polyurethane, polyester, silicone, etc. Various elastic resin materials can be cited as materials for the inner tube 21.

  The pusher marker 23 is fitted (adhered or welded) around the inner tube 21, fits in the lumen 12 of the outer tube 11, and pushes out the stent 39 from the outer tube 11 as the inner tube 21 moves.

  The pusher marker 23 may be made of one or more materials selected from the group consisting of stainless steel, nickel titanium alloy, tungsten, tantalum, gold, platinum, iridium, and palladium. For example, stainless steel is preferable as a material for the pusher marker 23 from the viewpoint of strength, workability, or economy.

  The core wire 25 is connected in parallel with the inner tube 21 and is further connected to the pusher marker 23. More specifically, a part of the side surface of the core wire 25 is connected to the inner tube 21, and an end portion of the core wire 25 is connected to one surface of the pusher marker 23 facing the proximal end side (in short, the core wire 25 is It is partially bonded or welded to the inner tube 21 and the pusher marker 23).

  With this configuration, the operator's force through the operation unit 41 connected to the inner tube 21 and the core wire 25 is not lost to the inner tube 21 and the core wire 25 (that is, the inner shaft 29). It is transmitted. Therefore, the stent delivery catheter 69 carrying the inner shaft 29 can place the stent 39 more safely and efficiently.

  Moreover, as a material of the core wire 25, materials, such as stainless steel or a nickel titanium alloy, are mentioned. Note that stainless steel is preferable as the material of the core wire 25 from the viewpoint of strength, workability, or economy.

  The distal tip 27 is bonded or welded to the distal end of the inner tube 21. The distal tip 27 makes it easier for the stent delivery catheter 69 to pass through the lesion (stenosis). Moreover, it is preferable that the front-end | tip chip | tip 27 has contrast property. In this way, the distal end of the stent delivery catheter 69 is grasped. Further, the relative position of the stent 39 relative to the vicinity of the distal end (distal end) of the outer tube 11 is grasped by the operation of the operator using the operation portion 41 attached to the proximal end of the inner shaft 29.

  The stent delivery catheter 69 as described above includes an outer shaft 19 including the lumen 12 and an inner shaft 29 inserted into the lumen 12 of the outer shaft 19, and the inner wall 11Nf surrounding the lumen 12 by the outer shaft 19. The stent 39 is attached (the stent 39 is cylindrical and is interposed between the outer shaft 19 and the inner shaft 29).

  The outer tube 11 included in the outer shaft 19 is a multilayer tube including an inner layer 11N that becomes the inner wall surface 11Nf and a reinforcing layer 11M that covers the inner layer 11N. The reinforcing layer 11M is a layer having unevenness, and the inner layer 11N captures the shape of the unevenness of the reinforcing layer 11M to make the inner wall surface 11Nf rough.

  Thus, when the inner wall surface 11Nf of the outer tube 11 is a rough surface, the contact area between the inner wall surface 11Nf and the outer surface of the stent 39 is easily optimized.

  For example, when the thickness of the inner layer 11N of the outer tube 11 is changed, the unevenness of the inner wall surface 11Nf of the inner layer 11 in which the shape of the uneven reinforcing layer 11M is reflected (specifically, the recessed area in the inner wall surface 11Nf). The ratio between the projected area and the projected area is changed), and the stent 39 can be easily held by the outer shaft 19 but can be easily pushed out by the pusher marker 23 of the inner shaft 29 (in short, the discharge load is likely to be optimized). ).

  That is, the inner wall surface 11Nf of the inner layer 11 in contact with the reinforcing layer 11M has an uneven surface that is easily pushed out by the pusher marker 23 of the inner shaft 29 while appropriately holding the stent 39 on the outer shaft 19 depending on the thickness of the inner layer 11N. Become.

  For example, when the thickness of the inner layer 11 is more than 10% and less than 100% with respect to the thickness of the reinforcing layer 11M, an appropriate uneven surface is likely to occur on the inner wall surface 11Nf of the inner layer 11 ( (It is a part of the inner layer 11 that overlaps the metal strand in the reinforcing layer 11M, and the concave portion is a part of the inner layer 11 that does not overlap the metal strand in the reinforcing layer 11M).

  If the thickness of the inner layer 11 is 10% or less with respect to the thickness of the reinforcing layer 11M, when the stent 39 is delivered by the stent delivery catheter 69, the stent 39 is deployed before reaching the lesioned part. Therefore, the case where the stent 39 cannot reach the lesion is likely to occur.

  On the other hand, when the thickness of the inner layer 11 is 100% or more with respect to the thickness of the reinforcing layer 11M, the stent 39 reaches the lesion when the stent 39 is delivered by the stent delivery catheter 69. May not be released from the outer shaft 19.

  In the following, Example 1 and Comparative Examples 1 and 2 that list specific examples of some members of the stent delivery catheter are described and evaluated. However, the stent delivery catheter 69 is not limited to this example.

[Example 1]
The outer tube 11 includes a polyamide elastomer outer layer 11T, a polytetrafluoroethylene (PTFE) inner layer 11, and a reinforcing layer formed by braiding a stainless steel flat wire having a width of 100 μm and a thickness of 25 μm. 11M. The inner layer 11 has a thickness of 15 μm (that is, the inner layer 11 has a thickness of 60% with respect to the reinforcing layer 11M).

  The inner tube 21 is made of a polyamide elastomer.

  The stent 39 is a self-expandable type. In this stent, a nickel titanium alloy pipe having a diameter of φ2.2 mm is laser-cut and expanded to φ6 mm and subjected to heat treatment. The outer diameter OD of the stent 39 was 6 mm, and the axial length LD was 30 mm.

[Comparative Example 1]
The inner tube 21 and the stent 39 are the same as the inner tube 21 and the stent 39 of the first embodiment. Although the outer tube 11 is formed of the same material as the outer tube 11 of Example 1, the thickness of the inner layer 11 is 2.5 μm (that is, the thickness of the inner layer 11 is relative to the thickness of the reinforcing layer 11M). 10%).

[Comparative Example 2]
The inner tube 21 and the stent 39 are the same as the inner tube 21 and the stent 39 of the first embodiment. Although the outer tube 11 is formed of the same material as the outer tube 11 of Example 1, the inner layer 11 has a thickness of 25 μm (that is, the inner layer 11 has a thickness of 100% with respect to the thickness of the reinforcing layer 11M). Is).

[Evaluation]
With respect to Example 1 and Comparative Examples 1 and 2, as shown in FIG. 7, delivery is performed without deploying the stent to the simulated lesion site of the lower limb simulated blood vessel 82 immersed in a warm bath 81 at 37 ° C. ± 2 ° C. We evaluated whether it was possible. Further, when the stent was released from the delivery catheter, the load applied to the operation unit (release load) was measured.

  In the stent delivery catheter that can deliver the stent to the virtual lesion site, the outer shaft is pulled to the proximal end side by the slider 83 at the movement distance of 80 mm and the movement speed of 10 mm / sec. The stent release load is measured using a 20 (N) force gauge 84 (manufactured by Nidec Sympo Corporation).

[Evaluation results]
The evaluation results are as follows. “◯” means that the stent has been delivered to the virtual lesion without being deployed, and “X” means that the stent has been deployed and has not reached the virtual lesion. Further, “−” means a case where the stent has expanded and the discharge load could not be measured, and “NO” means a case where the stent was not released from the outer shaft.

Delivery success / failure Release load (N)
Example 1 ○ 4.0
Comparative Example 1 × −
Comparative Example 2 ○ NO

[Other embodiments]
The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, as shown in FIG. 3, even if the distal end that is one of both ends of the cylindrical stent 39 coincides with the distal end that is one end of both ends of the outer tube 11 in the longitudinal direction of the outer shaft 19. Good.

  In FIG. 1 described above, the distal end of the stent 39 is separated from the distal end of the outer tube 11 so as to be hidden by the outer shaft 19 in the longitudinal direction of the outer shaft 19. However, in FIGS. 1 and 3, in the longitudinal direction of the outer shaft 19, the distal end (for example, the tip of the tip tip 27) that is one of both ends of the inner tube 21 is exposed from the outer shaft 19. It deviates from the distal end of the shaft 19.

  As shown in FIG. 4, in the longitudinal direction of the outer shaft 19, the distal end of the stent 39 is separated from the distal end of the outer shaft 19 so as to be hidden by the outer shaft 19. In the direction, the distal end of the inner tube 21 may coincide with the distal end of the outer tube 11.

  Further, as shown in FIG. 5, the distal end of the stent 39 coincides with the distal end of the outer shaft 19 in the longitudinal direction of the outer shaft 19, while the distal end of the inner tube 21 extends in the longitudinal direction of the outer shaft 19. The upper end may coincide with the distal end of the outer tube 11.

  In short, in the longitudinal direction of the outer tube 11, the distal end of the stent 39 coincides with the distal end of the outer tube 11 or is hidden from the outer tube 11 so as to be hidden by the outer tube 11. The distal end of the inner tube 21 is aligned with the distal end of the outer tube 11 or exposed from the outer tube 11 in the longitudinal direction of the outer tube 11. Deviates from the distal end.

  Further, the inner wall surface 11Nf of the outer tube 11 may be a rough surface without being caused by the unevenness of the reinforcing layer 11M. For example, as shown in FIG. 8, the rough surface of the inner wall surface 11Nf may be caused by unevenness of the resin itself that forms the inner wall surface 11Nf of the inner layer 11 without being caused by the unevenness of the reinforcing layer 11M.

11 Outer tube 11N Inner layer [first layer]
11M Reinforcement layer [second layer]
11T outer layer 12 lumen [hollow]
DESCRIPTION OF SYMBOLS 19 Outer shaft 21 Inner tube 23 Pusher marker 25 Core wire 27 Tip tip 29 Inner shaft 31 Strut 32 Substantially waveform component 39 Stent 69 Stent delivery catheter 81 Warm bath 82 Simulated blood vessel 83 Slider 84 Force gauge

Claims (5)

A stent delivery catheter for attaching a stent to a hollow outer shaft and an inner shaft that is inserted into the hollow of the outer shaft, and an inner wall surface that surrounds the hollow with the outer shaft,
The outer tube included in the outer shaft is a multilayer tube including a first layer that becomes the inner wall surface and a second layer that covers the first layer,
The second layer is a layer having irregularities,
The first layer is a stent delivery catheter in which the inner wall surface is roughened by imprinting the uneven shape of the second layer.   The stent delivery catheter according to claim 1, wherein the thickness of the first layer is more than 10% and less than 100% with respect to the thickness of the second layer.   The stent delivery catheter according to claim 1 or 2, wherein in the outer tube, the first layer is a resin layer, and the second layer is a layer formed of a metal wire. In the longitudinal direction of the outer tube, the distal end that is one of both ends of the cylindrical stent is aligned with the distal end that is one of both ends of the outer tube, or is hidden by the outer tube. And is deviated from the distal end of the outer tube,
In the longitudinal direction of the outer tube, the distal end that is one of both ends of the inner tube of the inner shaft coincides with the distal end of the outer tube, or is exposed from the outer tube. The stent delivery catheter according to any one of claims 1 to 3, which deviates from a distal end of the outer tube.   The stent delivery catheter according to any one of claims 1 to 4, wherein the stent is made of a shape memory alloy containing nickel and titanium.