Patent Application
20060276774
This invention relates to a thrombus suction catheter which is introduced into the body through the skin and sucks and removes debris (foreign matter) such as thrombus formed in blood vessels and atheroma liberated in blood vessels out of the body relying on a negative pressure applied through the proximal end of the catheter.
Thrombic diseases are not only those of cardiac (coronary arteries) diseases as represented by acute cardiac infarction but are also those occurring in the blood vessels of hands and legs. So far, these diseases were cured by surgical therapy which, however, has been replaced by an intervention therapy (catheter therapy through the skin) which is a low invasive therapy that is now rapidly spreading. This is because low invasive therapy is preferably carried out over therapies of a high invasive degree from the standpoint of QOL of the patient who is to be treated.
This invention relates to a thrombus suction therapy which is one of the intervention therapies. Thrombus suction therapy is one according to which a fine tube called a catheter is inserted up to a portion to be treated to suck and remove thrombus built up in the limbs such as the legs and arms.
The catheter for removing the thrombus is called a thrombus suction catheter and is used in combination with a suction tool. The thrombus suction catheter must have a strength such that the catheter wall will not be crushed by negative pressure and must further have an area (opening area) of the opening which is as large as possible in cross section, so that the sucked material can be easily discharged out of the body from the diseased part.
In conventional catheters, it has been attempted to improve the suction performance by using a single lumen tube. Without using a guide wire lumen for holding the guide wire, however, a difference between the inner diameter of the catheter and the outer diameter of the guide wire makes it difficult to operate the catheter in a desired direction. Furthermore, with the catheter of the so-called rapid exchange type that is generally used for the heart, the guide wire is located on the outer side of the catheter relative to the inner diameter of the sheath introducer which advances the catheter. Therefore, the size of the catheter itself must be decreased by an amount of the outer diameter of the guide wire so as to be smaller than the inner diameter of the sheath introducer, causing such a defect that the sectional area of the suction lumen must be decreased. (See Patent documents 1, 2 and 3, below).
Patent document 1: U.S. Pat. No. 5,827,229 (FIG. 5(a), FIG. 6(d))
Patent document 2: Japanese Patent No. 2812713
Patent document 3: JP-A-2004-65326
It is therefore an object of the present invention to improve the sucking force of a thrombus suction catheter by increasing the sectional area of the suction lumen and the operability of the catheter, which are conflicting functions with conventional catheters.
In order to solve the above problems, the present inventors have conducted a keen study and have arrived at a structure in which a distal end portion of a catheter is provided with a short guide wire shaft, the opening at the distal-most end portion of the catheter is formed by an angled cut surface to accomplish better permeation into the blood vessel and into the diseased part, and in which only a guide wire is permitted to advance into the tubular body to minimize an undesired decrease in the sectional area of the suction lumen.
That is, this invention is concerned with a thrombus suction catheter including a tubular body which has a suction lumen penetrating from a proximal end to a distal end thereof, and an opening formed by an angled cut surface at a distal end thereof, wherein a guide wire lumen is formed only in the distal end portion of the tubular body at the distal end, the guide wire lumen communicating with the suction lumen.
In a preferred embodiment, the opening is formed by a cut surface angled with respect to the axis of the catheter, the cut surface terminating in a necked-down tip at a distal side of the cut surface, and at least a portion of the cut surface on a proximal side of the cut surface being concave in the angled direction.
Further, the distal end portion of the tubular body comprises a resin kneaded with a contrast material for confirming the position of the catheter by X-ray examination or has an X-ray impermeable marker. The tubular body has a metal-knitted or coil reinforcing member. Further, the tubular body is provided with a hydrophilic coating. Additionally, the tubular body has differences in hardness in a plurality of steps which depend upon the differences in the hardness of the resins in a manner of becoming softer toward the distal end. Here, the distal end portion of the tubular body comprises a resin kneaded with a contrast material for confirming the position of the catheter in an X-ray examination or has an X-ray impermeable marker.
Described below is an embodiment of the thrombus suction catheter according to the present invention to which, however, the invention is in no way limited. The embodiment will be described hereinafter with reference to the drawings.
The thrombus suction catheter 1 according to the present invention includes a tubular body 2 which has a suction lumen 5 penetrating from a proximal end to a distal end thereof, an opening formed by an angled cut surface at a distal end thereof 11, the proximal end including a hub 3, the distal end portion 11 having a guide wire shaft 6 that follows the guide wire. The guide wire that passes through the suction lumen 5 communicates with a guide wire lumen 7 in the guide wire shaft 6 positioned at the most distal end portion.
The tubular body 2 has a guide wire lumen 7 at the distal end portion 11, and is of the so-called over-the-wire structure in which the guide wire that passes through the suction lumen 5 communicates with the guide wire lumen 7. The operator advances the guide wire in the blood vessel up to a peripheral diseased part, so that the thrombus suction catheter 1 of the invention is delivered along the guide wire. Further, the angled cut surface 4 is formed at the distal end portion 11. Therefore, the distal end portion becomes soft and thinner than the proximal end side of the tubular body 2 making it possible to improve the operability/permeability in the blood vessel and to treat highly bent portions and branched portions.
In the catheter of the invention, the guide wire lumen has a length in the range of 3 to 15 mm and a diameter in the range of 0.46 to 1.00 mm. The outer diameter of the guide wire shaft is in the range of 0.86 to 1.40 mm. The tubular body of the catheter has an inner diameter in the range of 1.35 to 1.95 mm and an outer diameter in the range of 1.70 to 2.30 mm. Typical guide wires have a diameter of 0.36 mm, 0.46 mm or 0.89 mm.
The method of joining the guide wire shaft 6 to the distal end portion 11 of the tubular body 2 does not impose any limitation on the effect of the present invention. That is, the junction may be accomplished relying on a known method such as heat-melting or adhesion.
On the distal end side of the tubular body 2, there can be used a resin kneaded with a contrast material in the distal end portion 11 of the tubular body 2 or in the whole tubular body 2 for confirming the position of the distal end portion of the thrombus suction catheter 1 by an X-ray examination. The contrast material is obtained by blending a resin with a contrast material such as bismuth oxide, bismuth sulfate or bismuth subcarbonate in an amount of about 20% to about 60%.
Further, the guide wire shaft 6 at the distal end portion 11 can be provided with an X-ray impermeable marker. The material of the X-ray impermeable marker is desirably a single metal such as a stainless steel, gold, platinum or iridium, or a metal material such as an alloy.
A portion between the distal end 11 and the proximal end of the tubular body 2 is reinforced with a knit or a coil of metal mesh as a reinforcing body 9 in the tubular body 2 to resist the crush of the catheter wall surface caused by a negative pressure at the time of suction and to impart force against the pushing of the catheter. This increases the strength of the tube and expands the suction lumen 5 by decreasing the thickness of the catheter wall owing to the increased strength. As the material of the reinforcing member 9, there can be preferably used a metal material such as a stainless steel or Ti—Ni.
The tubular body 2 is further provided with differences in hardness in three or more steps based on differences in the hardness of the resins in a manner of becoming softer toward the distal end and harder toward the proximal end.
At the diseased part in the blood vessel, therefore, a low hardness is provided while suppressing the permeability and invasion against the blood vessel. At the proximal end, no kinking occurs when operating or pushing the catheter which, therefore, can be pushed and turned.
Preferred structures include those structures/machining methods that have been used for contrast catheters/guiding catheters which are conventionally known. Though this is not to limit the effect of the present invention, preferred examples of the material constitution include three-layer structures as shown in
It is desired that the portion from the distal end to the proximal end of the tubular body 2 is provided with a hydrophilic coating from the standpoint of decreasing the invasion of the catheter against the blood vessel wall and improving permeability/operability.
The method of hydrophilic coating and the material are not intended to limit the effect of the invention, and can be selected depending upon the properties of the tubular body 2 and the guide wire shaft 6 that are used. For example, there can be preferably used a hydrophilic polymer such as a poly(2-hydroxyethyl methacrylate), a polyacrylamide or a polyvinyl pyrrolidone.
An example of the thrombus suction catheter of the invention will be described below.
The tubular body 2 has an outer diameter of 2.0 mm, an inner diameter of 1.65 mm, a length of 700 mm, and has a structure of an inner layer 10 of PFA and an intermediate layer 9 of a reinforcing member of a stainless steel plain knitted structure, and an outer layer 8 of a nylon elastomer having difference in hardness in three steps (resin hardnesses of 40 D, 55 D and 72 D) along the length of the catheter.
A nylon elastomer blended with 40% of bismuth oxide is used as the contrast material of the distal end portion. The distal end portion 11 of the tubular body 2 is cut at an angle by using a cutting blade to form an angled cut surface 4 extending to the distal end. A mandrel is inserted in a guide wire shaft 6 which has an outer diameter of 0.70 mm, an inner diameter of 0.55 mm and a length of 10 mm, the cut portion at the distal end portion 11 is wrapped around the guide wire shaft and is melt-adhered by heat treatment, the mandrel is withdrawn and the distal end portion is trimmed.
A hub 3 injection-molded by using a polycarbonate is adhered to the proximal end of the tubular body 2 by using a UV adhesive, and a portion over a length of 200 mm beginning from the distal end of the catheter is provided with a hydrophilic coating thereby to obtain a thrombus suction catheter 1.
In the above embodiment, the guide wire lumen 7 is provided in the guide wire shaft 6. However, the guide wire lumen 7 can be formed by simply wrapping the cut portion at the distal-most end of the distal end portion 11 around a mandrel or the like to form a lumen and heat-treating the wrapped portion. In the above embodiment, it is desired that the tubular body 2 is flexible and has a difference in hardness in three or more steps in a manner of becoming harder toward the proximal end side. The difference in the hardness, however, may be in two steps.
According to the present invention, the thrombus suction catheter includes a tubular body which has a suction lumen penetrating from a proximal end to a distal end thereof, and an opening formed by an angled cut surface at a distal end thereof, wherein a guide wire lumen is formed only in the distal end portion of the tubular body, the guide wire lumen communicating with the suction lumen. Therefore, sucking force is improved by the increased sectional area of the suction lumen and the operability of the catheter is improved, which are conflicting functions with the conventional catheters.
Further, the distal end portion of the tubular body comprises a resin kneaded with a contrast material for confirming the position of the catheter during X-ray examination or has an X-ray impermeable marker, offering a better view during therapy. The tubular body, further, has a metal-knitted or coil reinforcing member, improving the strength of the tube while decreasing the thickness thereof. Further, the tubular body can be provided with a hydrophilic coating, decreasing the invasion of the catheter against blood vessel walls and improving permeability/operability.
Additionally, the tubular body has differences in the hardness in three steps depending upon differences in the hardness of the resins in a manner of becoming softer toward the distal end. At a diseased part in a blood vessel, therefore, low hardness is provided while suppressing the permeability and invasion of the catheter against the blood vessel. At the proximal end portion, no kinking occurs when operating or pushing the catheter which, therefore, can be pushed and turned.
This application claims priority of Japanese Patent Application No. 2005-162005 filed Jun. 1, 2005, which is incorporated herein by reference.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-162005 | Jun 2005 | JP | national |
