JPH0663155A - Stent - Google Patents

Abstract

PURPOSE:To prevent a tumor from wetting in a medical stent and to prevent constriction and blocking of the stent and to enable local dosage of a medicine by forming the stent from a thermosensitive magnetic material which generates heat in response to an external alternating magnetic field and which has a low curie temperature, and by allowing the stent to carry at its outer peripheral surface a thermosensitive polymer and the medicine. CONSTITUTION:A magnetic material which generates heat in response to an external alternating magnetic field and having a self-temperature control ability is formed into a tubular, zigzag, mesh-like or spiral shape or the like, so as to form a medical stent which is applied, coated or stuck thereon with a medicine together with a thermosensitive polymer. This stent is retained in the human body so as to treat constriction or blocking of an annular organ or a blood vessel caused by a malignant tumor, and to effectively restrain the multiplication of the annular tumor around or in the stent with the use of a thermal treatment. Accordingly, local dosage of a medicine is made possible. Further, since a local thermal treatment can be made, it can be widely applicable up to the progress of a cardio-coronary arteries, and accordingly, it is possible to carry out positive treatment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-generating stent, and more particularly, it can be used for treating stenosis / occlusion caused by various causes such as tubular organs and blood vessels in a living body, and malignant tumor such as cancer. The present invention relates to a stent capable of local hyperthermia in a magnetic induction system in hyperthermia (hyperthermia), which is one of the treatment methods, and further capable of local drug administration.

[0002]

2. Description of the Related Art As a treatment method for obstructive jaundice, which is not an indication for surgery, an endoprosthesis which completely inserts an internal fistula by inserting a tube into a biliary tract closure is introduced, and then a drainer tube is externally attached to the body. It is no longer necessary to send it to. Therefore, the patient does not have to carry a bile storage bottle, is free from infection and discomfort at the insertion part of the drainer tube, and is emotionally and mentally stable.
f Life) can be expected to be improved, and bile bile flows out into the duodenum, which provides nutritional and physiological stability, and
Bathing is also possible, and it has social benefits such as expanding the range of activities. However, in spite of various improvements and contrivances, it is the current situation that the tube often cannot withstand long-term use due to deviation, stenosis or blockage.

Prevention of reclosure depends largely on the material of the tube and its inner diameter. With respect to the tube diameter, in particular, there is an expectation for an expandable metallic stent (EMS) capable of inserting a stent having a large diameter, which has been considered impossible until recently. There are currently three types of EMS, and there are a self-expanding type that is made of stainless steel and has a self-expanding force, a balloon-expandable type that expands with a balloon, and a shape memory alloy type that expands with body temperature.

Biliary endoprosthesis using EMS is
It is mainly used for biliary tract obstruction and postoperative stenosis due to malignant tumors, and has demonstrated its effectiveness. The effect of the conventional dilatation with a balloon is often temporary, and expectations for the emergence of an EMS that functions for a long time are great. In addition, since EMS has the ability to expand outward, it can counter internal stenosis due to a tumor, and thus it can be applied to cases where the bile duct is excluded from the outside, such as pancreatic cancer and lymph node metastasis. However, the cancer lesions infiltrated and exposed in the lumen of the bile duct
Premature re-occlusion by increasing through the gap of the EMS wire is the greatest drawback of this expandable metallic viral endoprosthesis (EMBE). Therefore, it is often necessary to combine anticancer therapy such as radiation therapy and hyperthermia. However, bile cancer, biliary tract cancer, pancreatic cancer, etc. are originally low in radiation sensitivity and have large side effects, so that EMS remains functioning for a long period of time.
It is virtually impossible to use them together. Also,
It is not suitable for sites where the lumen is too narrow, and has the drawback that the stent will collapse if it is under the pressure of the tumor.

The deviation of the stent, which has been a problem in the past, is EM.
Almost all the problems have been solved by S, but for the occlusion and stenosis of the stent due to the progress of tumor growth, radiation therapy and chemotherapy are very palliatively performed.
In particular, EMS in malignant biliary obstruction is positioned as a part of multidisciplinary treatment. The conventional tubular endoprosthesis was able to reduce the obstruction due to sludge, which was the cause of the early occlusion, but the problem of preventing the growth of the tumor growing in the stent lumen has not been solved yet. Therefore, development of an EMS that can function for a sufficiently long period even for stenosis or obstruction due to a malignant tumor is awaited.

Further, as a cause of cardiac coronary artery stenosis which is a cause of myocardial infarction, there are cases where the blood vessel wall becomes thicker and where it becomes narrower due to thrombus in the blood vessel. As the former reason, there are cases where cholesterol adheres to the blood vessel wall to make it narrow, and blood vessels in the blood vessel wall grow in a layered manner to thicken the blood vessel wall, resulting in narrowing of the blood vessel. In particular, when the blood vessel in the blood vessel proliferates to narrow the blood vessel, the only treatment method is the bypass operation of the coronary artery. But,
Patients with such coronary artery stenosis are not able to withstand the bypass surgery and are limited to treatment with a passive drug or the like having a small therapeutic effect.

Further, the drug administration method is usually systemic administration by intravenous injection using a syringe. However, side effects due to toxicity of the drug to be administered have become a problem. That is, the anticancer agent and the like have similar toxicity demonstrating values to tumor cells and normal cells regardless of their origin and action. Therefore, how to selectively concentrate the drug on the affected area and allow it to act for a long time is a problem.

[0008]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The problem to be solved by the present invention is to insert the present stent into a stenosis or occlusion of a tubular organ or a blood vessel which has progressed beyond the scope of conventional stent insertion, and to locally heat the tissue. To prevent the invasion of the tumor into the stent and the stenosis and occlusion of the stent due to the pressure of the tumor from around the stent, and to maintain its effectiveness for a long period of time. And the controlled release of the drug.

Therefore, an object of the present invention is to provide a tubular organ and a blood vessel in a living body which are narrowed and occluded by a malignant tumor such as cancer,
With a stent, a stent that can be effectively opened for a much longer period than the conventional one, and local hyperthermia can be applied by soft heating method in magnetic induction system, and local drug administration or drug release can be controlled. It is the one we are trying to provide.

[0010]

[Means for Solving the Problems] As a result of various studies to solve the above problems, a hollow stent was manufactured using a magnetic material having a low Curie temperature, and a drug was applied to the surface of the hollow stent along with a temperature-sensitive polymer. , Coated or deposited. The manufactured stent is self-expanding, small in a catheter, and expands about 10 times in diameter when taken out of the catheter. Furthermore, when this stent was excited in physiological saline at a magnetic field strength of 4 kA / m and a frequency of 200 kHz, it was possible to heat the ambient temperature to 43 ° C. The present invention has been completed by confirming that the dispersed or dissolved drug is released.

In the present invention, the Curie temperature of the magnetic material can be freely set according to the therapeutic need. As a magnetic material having a low Curie temperature, JP-A-2-47243 is known.
There are temperature-sensitive amorphous alloys, Fe-Pt alloys, and the like described in Japanese Patent Laid-Open No. 2-61036 and Japanese Patent Laid-Open No. 2-61036. The drug may be applied to, coated on or adhered to the stent by any method. Controlled release of the drug is possible by applying, coating or adhering the drug with a temperature sensitive polymer. Here, the temperature-sensitive polymer means a polymer that melts at around 43 ° C. and is safe for the living body.

[0012]

By placing the stent of the present invention in a living body, it is possible to treat stenosis or occlusion of tubular organs and blood vessels due to malignant tumors, etc. Further, the drug is positively and effectively administered only to the affected area. It is possible to

[0013]

EXAMPLE The structure of the stent according to the present invention is a hollow structure in which zigzag wires to which springback of a material is applied are connected by spot welding or the like. That is, the structure may be spiral, zigzag, mesh or tubular. FIGS. 1A and 1B show the configuration of a zigzag stent using a magnetic wire. Reference numeral 1 is a wire, and portion 2 is a joint such as welding. 3 is a wire for maintaining the shape. 1A is a series of equations, and FIG.
Indicates a dual type.

The application of the drug was carried out by immersing the stent in a melted temperature-sensitive polymer in which the drug was dispersed and mixed, and then pulled out of the liquid and dried. When attached together with a temperature-sensitive polymer, the stent is made of magnetic wire with self-temperature control, so the high-frequency magnetic field is applied to the stent to heat it, causing the polymer to melt and Release control is possible. That is, the drug is not released unless a high-frequency magnetic field is applied from the outside. Application,
Selection of drug and temperature-sensitive polymer to be coated or attached,
It shows that the release control of the drug can be freely set by selecting the Curie temperature of the magnetic wire. FIG. 2 shows a temperature rise curve of physiological saline when the zigzag stent was immersed in physiological saline and excited with a magnetic field strength of 4 kA / m and a frequency of 200 kHz. From this, it can be seen that the temperature range required for hyperthermia is heated in about 3 minutes. At this temperature, the temperature-sensitive polymer melts, and the drug is released to the affected area.

[0015]

EFFECTS OF THE INVENTION By placing the stent of the present invention in a living body, it is possible to treat stenosis or occlusion of tubular organs and blood vessels caused by malignant tumors, etc., and it is possible to increase the growth of malignant tumors around the stent or in the stent by hyperthermia. Can be treated, and local drug administration is possible. Furthermore, since local hyperthermia can be performed, it can be expected that the indication will be extended and effective for a longer and more effective period than the conventional one, or even in advanced cases such as cardiac coronary arteries that have not been indicated, and active treatment can be performed.

[Brief description of drawings]

FIG. 1 (a) is a diagram showing a constitution of a series of zigzag stents used in the present invention, and FIG. 1 (b) is a diagram showing a constitution of a dual zigzag stent used in the present invention.

FIG. 2 is a graph showing the temperature rise of the stent when excited.

[Explanation of symbols]

 1 magnetic wire 2 magnetic wire joint 3 shape retention wire

 ─────────────────────────────────────────────────── ─── Continuation of the front page (71) Applicant 392013648 Hidetoshi Matsuki 1-9-29 Minami Yagiyama, Taichiro-ku, Sendai-shi, Miyagi (72) Inventor Koji Hemi 4-14-1, Suehiro, Kumagaya, Saitama Stock Company Riken Kumagaya Works (72) Inventor Sakae Minagawa 4-14-1, Suehiro, Kumagaya-shi, Saitama Stock company Riken Kumagaya Works (72) Inventor Tomoya Sato 1-7 Aramachi, Fukushima-shi, Fukushima Prefecture (72) Inventor Kimura Wase 1-4 Waseda Izumi, Fukushima-shi, Fukushima Prefecture (72) Inventor Masahiro Sato 13-8 Sakuradai, Tazawa, Fukushima-shi, Fukushima Prefecture (72) Hidetoshi Matsuki 1-9-9, Yagiyama Minami, Taihaku-ku, Sendai-shi, Miyagi Prefecture

Claims (1)

[Claims] 1. A tubular shape, a zigzag shape, which is made of a magnetic material that generates heat by an external alternating magnetic field and has self-temperature controllability.
For medical stents of various shapes such as mesh and spiral
A stent characterized in that a drug is applied, coated or adhered with a temperature-sensitive polymer.