MEDICAL GUIDING MICRO-TUBE

Abstract: A medical guiding micro-tube consisting of a tube (1) of a synthetic resin; a balloon (4) joined to the front end of the tube (1) and having an outer diameter substantially equal to that thereof, and a small fluid leak bore (14) as necessary; and a spherical member (15) provided in the balloon and connected to the front end of the tube by a thread (16) of a limited length. This micro-tube is capable of guiding liquid medicine safely to peripheral blood vessels. If this micro-­ tube is used as a leak balloon catheter, the leaking of liquid medicine can be timed accurately, and the timing of the leakage of liquid medicine can be regulated with a high producibility.

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to guiding microtubes for inserting into blood vessel, according the preamble claim 1. BACKGROUND OF THE INVENTION An angiography in which lesions on blood vessel are diagonozed by injecting a contrast medium into blood vessel and studying the flow and expansion of the contrast medium and a topical administration therapy in which theraperitic liquid is injected into blood vessel have been widely carried out by the development of Seldinger's method in which catheter is inserted into blood vessel transdermally. Heretofore, the catheter used for injecting therapeutic liquid into lesion on blood vessel has been used by firstly introducing a guide wire thereof within the blood vessel near the lesion and then inserting it along the outer wall of the guide wire. As the guide wire, in general, a metal guide wire of stainless steel and stainless steel coil has been used and has drawbacks such as liability to injuring the inner wall of blood vessel during operation. Recently so called flow guide wire, of which tip is floated on the blood flow and introduced into peripheral blood vessels, has been proposed, but it also has drawbacks, for example, in which the structure is so fine that it is difficult to pass through such blood vessels having many windings and bendings and it is substantially impossible to introduce it up to lesion of peripheral blood vessels. Also, a guide catheter which can perform the roles of both catheter and guide wire and well known leak balloon catheter have drawbacks, for example, the liability to injuring the inner wall of blood vessels, the difficulty of passing through peripheral blood vessels and the instability of the operation. US-A- 4 029 104 discloses a medical microtube comprising a plastic tube having a fluid outlet hole at the tip of the tube and a fluid inlet hole at the rear end of the tube. A cylindrical ballon is attached to the tip of the tube, the lumen of said balloon being in communication with the fluid outlet hole. This ballon catheter is provided with a simple discharge orifice. DISCLOSURE OF THE INVENTION The object of the present invention is to present a flow guide wire and/or a flow guide catheter (called as a guiding microtube hereinunder) which improve the disadvantages of the above prior art. Another object of the present invention is to present a flow guide wire which can be selectively introduced into peripheral blood vessels by simple handling in short time and be easily withdrawn and further be handled very safely. Another object of the present invention is to present a flow guide catheter particularly a leak balloon catheter which can easily be introduced into peripheral blood vessels and be handled safely by controlling the infusion of therapeutic liquid easily and certainly. The fundamental structure of the guiding microtube of the present invention is given in claim 1. Preferred embodiments of the present invention are given in the subclaims. The guiding microtube of the present invention may perform function of a a leak balloon catheter. When used as a leak balloon catheter, a fluid outlet hole is provided to the balloon having a valve mechanism. Said valve mechanism comprises a movable stopper which is engaged with the catheter, and said stopper makes said outlet hole of therapeutic liquid open or close according to the transformation of said balloon caused by the change of the inner pressure of said balloon to form a valve mechanism. To understand the invention, the illustration will be given to a guiding microtube used as a flow guide wire. Fig.1 is an elevation view (a) and a cross section view (b) of an embodiment of the leak balloon catheter of the present invention. This comprises a balloon 4 which is a flexible elastic material and provided with a fine fluid outlet hole 14 at the tip, said balloon attaching to the tip of the tube 1 which has an inner channel 2 and is the body of the catheter. Within the lumen of the balloon 4 there is a stopper 15 which contacts directly with a fluid outlet hole 14 for exiting therapeutic liquid, and one end of fine fiber 16 is fixed at the stopper 15 while another a little loosened end of it is fixed in adhesive 9 through the engagement between the tube 1 and the balloon 4. All of these composes a valve mechanism which will be described below. The engagement portion of the balloon 4 and the tube 1 is fastened with fiber, and in order to avoid abnormal storage of blood, the knots and unevenness are finished smoothly with adhesive 9 and the difference between the rear end of the balloon and the catheter is finished to gentle grade. A small fluid inlet hole 5 for introducing therapeutic liquid is provided at the operational portion of the tube 1, and is interconnected with the inner channel 2 and the lumen of the balloon, and the inner channel 2 is utilized as a fluid transfer channel. Fig.2 shows an elevation view of an embodiment in which a pipe 91 comprising non-X ray transmission material (usually metal) is inserted between a fluid outlet hole 14 and a stopper 15. The pipe 91 inserted is fixed by fastening with fiber 18 on the outer circumference of the balloon 4. Fig.3 shows an embodiment in which the balloon 4 is attached to the tip of the tube by narrowing the outer diameter of the latter through drawing, the outer diameter of the attached balloon 4 being the same as that of the tube 1. Fig.4 is an elevation view of an embodiment in which a pipe 92 comprising non-X ray transmission material is employed for the connection between the tube 1 and the balloon 4. In Fig 4, the tube 1 and the balloon 4 are capped each other from both ends of the pipe 92 comprising non-X ray transmission material along with their outer walls, and the outer circumferences of the tube 1 and the balloon 4 are fastened with yarn 18 to fix on the pipe 92. The knots of yarn and the unevenness of the connection are made smooth with adhesive 9. In this case, the yarn 16 connected with a valve mechanism is fixed between the pipe 92 and the balloon 4, and a stopper 15 engages with the tube 1. Then the structures of each part of a leak balloon catheter of the present invention will be illustrated. The balloon 4 attached at the tip of the tube 1 is an empty elastic body having a circular cross section which is oblongly cylindrical or spheroidal as well as flexible, and it has a sufficient strength not to be cut when dilated and introduced to the lesion by means of blood flow. At the tip of the elastic balloon 4, a fine fluid outlet hole 14 is bored. A stopper 15 which contacts directly from the lumen of the balloon 4 with the pipe 91 comprising non-X ray transmission material and positioned at or in front of the fluid outlet hole 14 is a ball of which diameter is by about 50% larger than that of the outlet hole of fluid 14 and is smaller than that of the lumen of the balloon 4. The yarn 16 connecting them in fine and flexible so that the movement of the stopper 15 is free, and is loosened while the balloon 4 is not yet dilated, and its end is fixed between the tube 1 and the balloon 4, and has strength enough not to be cut or off under the pressure of the therapeutic liquid stream. The diameter of the yarn 16 is preferably about 10-40µ. The fluid inlet hole 5 near the operational portion of the tube 1 is normally covered with a cap, and has a structure equipped with a connector or an injector. The material of the tube comprising a catheter is not particularly limited, but melt extrusion moldable tubes such as one of synthetic resins such as polyamides, polyesters, polyolefins and fluororesins are preferably used. As the catheter used for diagnosis and treatment of blood vessels within brain is required to be soft, silicone and polyurethane are suitably used. For the elastic balloon 4 attached at the tip, very flexible rubber latex, silicone rubber or urethane elastomer are preferably used. The balloon of rubber latex coated with silicone oil is preferred, because it prevents degradation or formation of thrombus in contacting with blood. The thinner elastic body, for example, having the thickness of less than 300µ preferably less than 200µ is suitable. The diameter of the fine fluid outlet hole 14 is about 100-400µ, since it becomes larger by dilatation even it is usually smaller. The therapeutic liquids used for dilatation of the balloon include physiological saline or contrast media, and they are extruded through the fluid outlet hole 14. The size of each part of the leak balloon catheter of the present invention may be dependent on age of patient, physical constitution, severity of illness etc. and cannot be particularly defined. The normal typical sizes will be given as follows. Diameter (mm) Length (mm) Tube 0.5 ∼ 3.5 600 ∼ 2500 Balloon 0.4 ∼ 5.0 4 ∼ 10 X ray Non transmission metal pipe 0.5 ∼ 2.5 1 ∼ 4 The ball-like body used for a stopper 15 comprising a valve mechanism of the leak balloon catheter of the present invention may be of silicone or other synthetic resins, and stainless steel or steel, the latter two being preferred because of easy processing for boring a hole connected with yarn. When it is placed directly contacting with the pipe 91 consisting of non-X ray transmission material in Fig.2, silicone coating on the surface of the ball-like body is suitable because of close contacting. In Fig.2, as the pipe 91 consisting of non-X ray transmission material has a hole, the fluid outlet hole 14 is not always necessary for the balloon. When the tip of the balloon is opened, the operation should be careful because the therapeutic liquid remained in the lumen of the pipe is dried and clogged by withdrawing the air in the lumen of the catheter before use. The non-X ray transmission materials used herein include pipes of metals having superior angiographic formation by X ray radiation, typically gold or platinum, and metals being stable in therapeutic liquid are preferred. Alternatively there are pipes used rigid synthetic resin as materials which are coated with a mixture of metal powder having angiographic formation ability by X ray radiation such as tungsten or tantalum etc. and adhesive, but in the absolute concentration of metal the above pipes are better. 0.2-0.6 mm of the diameter of hole of the pipe can be used without any difficulty of passing through therapeutic liquid. When the plane of the pipe 91 contacting with the stopper 15 is made to be conical, it is more convenient because of greater contacting area with the ball-like body. The stopper 15 used for a valve mechanism normally contacts with the fluid outlet hole 14 or the pipe 91 comprising non-X ray transmission material from the lumen of the balloon 4, and when therapeutic liquid is injected into the lumen of the balloon 4 from the empty portion 2 which is a fluid transfer channel of the tube 1, it is at first pressed toward the fluid outlet hole 14 by the pressure of the liquid. As the therapeutic liquid is injected, the balloon begins to dilate because of no outlet, and finally it becomes dilated towards the direction in which the length of the balloon elongates. The yarn of the stopper under pressure elongates pressed with the fluid outlet hole 14 while the yarn 16 maintains loosen, but when the yarn 16 is stretched by the longation of the balloon 4, the stopper 15 is apart from the fluid outlet hole 14, and the fine hole opens and the leak of therapeutic liquid begins. Then even when the injection of therapeutic liquid stops, the leak of therapeutic liquid continues for some time under the pressure from autoshrinkage of the balloon 4. In time the lenthwise shrinkage of the balloon 4 begins. In this case, since the stopper 15 receives the pressure of therapeutic liquid which continues to leak, the yarn 16 maintains stretched, and then the stopper 15 contacts with the fluid outlet hole 14 to choke up and stop the leak of therapeutic liquid. The form of the balloon is maintained as long as the injection pressure does not change. (Examples) The examples will be given below to illustrate the present invention further. Example 1 (Leak balloon catheter) As shown in Fig.1, a stopper 15 in which nylon yarn 6 having diameter of 0.03mm had fixed with adhesive on a stainless steel ball of 0.3mm of diameter with adhesive (Sankyo Pharmaceutical Co.: "ARON α A") was inserted into the lumen of a balloon 4 in which a fine hole had been bored with sharp-pointed piano wire of 0.2mm of diameter at the tip of the rubber latex having 0.4mm of inner diameter, 0.15mm of thickness and 4mm of length. At the tip of a catheter comprising polyethylene tube of 0.1mm of inner diameter, 0.6mm of outer diameter and 700mm of length, the balloon 4 having nylon yarn 4 of about 4mm in length was attached. Two parts of the engaged balloon was fixed by fastening tightly, and then two-liquid type epoxy resin (Cemedine Co., "High-Super"® was applied and the surface was finished smoothly. Into the opening portion of the operational portion of the tube a 25G injection syringe was inserted to give a leak balloon catheter. Physiological saline was injected into the leak balloon catheter through a fluid inlet hole equipped with 25G® injection syringe attached with a three way coke from an injection cylinder of volume of 2.5 ml, and the balloon was dilated at about 2.0 kg/cm². When the valve was closed, the balloon maintained the form, and no leak from the fluid outlet hole was noticed. Example 2 (Leak Balloon catheter) In Fig.2, a stopper 15 in which nylon yarn 6 of 0.04 mm of diameter had fixed with adhesive on a stainless steel ball of 0.3 mm of diameter and the surface had been coated with silicone (Toray Silicone: "SH781"®) was inserted into the lumen of a rubber latex balloon 2 having 0.4 mm of inner diameter, 0.2 mm of thickness and 5 mm of length. At the tip of the balloon 2 a fine hole was bored with sharp-pointed piano wire of 0.2 mm of diameter, and within the lumen inserted was a gold pipe 91 having 0.2 mm of inner diameter and 0.5 mm of outer diameter of which one end of the lumen had been finished conically with very fine drill, the insertion being done from another unfinished end. The balloon 4 containing such valve mechanism and having nylon yarn of about 4 mm in length attached at the tip of a tube 1 in which 6 cm of the tip of a polyester tube having 0.4 mm of inner diameter, 0.18 mm of outer diameter and 1,500 mm of length had been elongated by heating and processed taperingly so as to be larger towards the operational portion. The engaging portion and the gold pipe inserting portion were fixed on the circumference of the balloon by fastening with polyurethane yarn, and further with two-liquid type epoxy resin (Nagase-Ciba: "ARALDITE"® "HARDNER"®) to finish smoothly, and unevenness between the balloon and the catheter was made gentle grade. From the opened operational portion of the catheter, a tapered tungsten wire having 0.3 mm of diameter was inserted, and at the opening 25G injection syringe was inserted, the space being filled with epoxy resin. All of the catheter was coated with silicone (Dow-Corning: "MDX4-4159"® to give the leak balloon catheter. After sterilization with ethylene oxide gas, it was used for clinical test in which it was inserted from femoral artery to hepatic artery via abdominal artery. For the leak balloon catheter of the present invention inserted into femoral artery by Seldinger's method, the balloon was not dilated from femoral artery to abdominal artery, but contrast medium ("Andiographin"® was injected under pressure through an injection syringe at the fluid inlet hole 5 from an injection cylinder filled with the medium through abdominal artery to hepatic arteries to dilate the balloon which floated in blood flow. Adding slight pressure to dilate the blood vessel itself, it easily reached left hepatic artery and the injection of therapeutic liquid (antitumor agent) could be done. The gold pipe 91 at the tip portion could be visually traced by an X ray radiation monitor, and when the leak balloon catheter was withdrawn, it could be clean only by wiping with gauze and no blood was noted. The leak balloon catheter of the present invention can float on blood flow and move freely by adjusting the size of the balloon depending on the state of the blood vessel of the patient after the insertion into the blood vessel. By this function, the guiding ability of the balloon is remarkably improved, and the balloon can reach the peripheral part without creaping into or injuring inner wall of blood vessel even at the branched part of blood vessel and would blood vessel. Therefore, the burden of patients is not only relieved, but the concern of the operator is remarkably lightened. When a contrast medium is used for the dilatation of the balloon, observation by monitor is definite, and therapeutic liquid is readily replaced and injected when it reaches lesion and the therapeutic liquid is injected under pressure. Using a pipe of non-X ray transmission metal at the tip, even at the injection of therapeutic liquid, the case in which the tip of the catheter is transferred to another blood vessel can be easily found by the movement of the blood vessel and the operation can be amended. Since the infusion of therapeutic liquid can be carried out maintaining the dilated tip balloon, it is possible to effect the infusion under limitation or choking up of blood flow. This results in decrease of the infusion amount and the effect of side complication, and in a method of forming angiographic image in blood vessel little vagueness in angiographic image is obtained to decrease misdiagnosis. As the surface of the catheter is smooth and unevenness is finished smoothly, there is no stagnation of blood flow and by coating with silicone the formation of thrombus is also prevented. BRIEF EXPLANATION OF DRAWINGS Figs.1-4 show a guiding microtube of the present invention suitable for the use as leak balloon catheter. Fig.1(a) is an elevation view of the fundamental structure thereof, Fig.1(b) is a cross sectional view of part A-A' in Fig.1(a), and Figs.2, 3 and 4 are elevation views of the tip portions of other embodiments.

Claims: A medical guiding microtube suitable for the use as a leak balloon catheter comprising a plastic tube (1) having a fluid outlet hole (13) at the tip of the tube (1) and a fluid inlet hole (5) near the rear end of the tube (1), a cylindrical or spheroidal balloon (4) being attached at the tip of the tube (1) so as to interconnect the lumen of the balloon (4) with the fluid outlet hole (13), an outlet hole (14) of therapeutic liquid at the tip of the balloon (4), and a valve mechanism (15') within the lumen of the balloon (4) characterized in that removable stopper (15) forms part of the valve mechanism (15') and chokes the outlet hole (14) depending on the transfiguration of the balloon (4) caused by the inner pressure. A medical guiding microtube according to claim 1, characterized in that said stopper (15') is engaged with the tip of said tube by means of yarn (16). A medical guiding microtube according to claim 1, characterized in that a pipe (91) comprising non-X ray transmission material is provided at the fluid outlet (14) of the balloon. A medical guiding microtube according to claim 1, characterized in that a pipe (91) comprising a non-X ray transmission material is used for connecting the balloon (4) with the tube (1). A medical guiding microtube according to claim 1 characterized in that the stopper (15') is a ball-like body.

Inventors: FUTAMI, YASUHIKO, HAGIO, MITSUYUKI, NOGUCHI, NORIYASU, YAMADA, RYUSAKU
Applicants: TORAY INDUSTRIES, INC.
Application year: 1986
Main classification: A61M25
IPC codes: A61M39, A61M25