JPH0239255B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a blood bypass tube, and more particularly to a bypass tube used for bypassing blood during vascular surgery. In recent years, rapid advances in cardiovascular surgery have made it possible to perform difficult surgeries that were previously considered impossible. However, for this purpose, powerful medical instruments must be developed at the same time. For example, surgery for an aortic aneurysm has traditionally been considered extremely difficult. When performing this type of surgery, stopping the flow of blood to the entire body, which is the life source of a person, will immediately lead to death, so in aortic aneurysm surgery, the surgical site is bypassed to preserve life. blood must be sent throughout the body. The unresolved issues required for blood bypass tubes used for such purposes are (1) how to remove the small amount of air that gets mixed into the bypass tube when the blood bypass tube is set; (2) How can we provide versatility that can be freely applied to blood vessels of various diameters?
(3) How to prevent blood clots from coagulating when blood flows into the bypass tube, and there has been a strong desire to solve these problems. The present invention solves these problems, and the both ends of a flexible tube are tapered toward the tip, and the tube is connected to the inner surface of the tube. It is characterized by having at least one side tube, and preferably the inner surface of the tube, that is, the surface that comes into contact with blood during use, is coated with an antithrombotic material, and the antithrombotic material is polyurethane or A composition having a surface structure in which polyurethane forms a continuous phase (sea phase) and polysiloxane forms an independent phase (island phase) is preferably used. The features of the present invention will be explained below using examples. FIG. 1 shows a first bypass tube according to the present invention.
An example is shown below. The one shown in Figure 1 is made of polyvinyl chloride containing dioctyl phthalate as a plasticizer and is seamlessly formed on the inside.
80 parts by weight of dioctyl phthalate is used. The total length is 50 cm, and the inner diameter of the straight pipe part of the tube is 10 mm, but as shown in the figure, both ends of the tube are tapered so that the inner diameter becomes tapered. The length of this tapered portion is set to 5 cm, and the inner diameter at both ends is 2.5 mm. Approximately in the center of the tube, there is a T-shaped side tube made of plasticizer-containing polyvinyl chloride with the same composition, which communicates with the inner surface of the tube and is seamlessly molded into one piece. The length is 25 mm, and the inner diameter of the side tube is 3 mm. The wall thickness of the tube is approximately 1mm at the inner diameter of 10mm, and the tip of the tube is 0.5mm.
Both ends of the tube are formed so that the thickness becomes thinner toward the tip. However, it is not always necessary to reduce the thickness. The side tube is for removing air that gets mixed in when the blood bypass tube is sutured to the blood vessel, and this side tube part does not necessarily have to have the same composition as the tube main body. The proportion of plasticizer may be increased (for example to 95% by weight relative to 100% by weight of polyvinyl chloride). Such blood bypass tubes are made by mixing polyvinyl chloride with an appropriate amount of plasticizer (usually 40 to 100 parts by weight per 100 parts by weight of polyvinyl chloride) to form a so-called polyvinyl chloride paste sol. can be molded by a known slush method. This slushing method involves heating a mold with a preset shape, immersing it in paste sol, gelling the surface of the mold with heat, and then removing the mold from the sol bath and curing ( This is a method of molding by heat treatment). To change the composition of the side tube, remove the side tube up to the point indicated by the dotted line in Figure 1, and use a paste sol (referred to as sol A) containing, for example, 80% by weight of dioctyl phthalate based on 100% by weight of polyvinyl chloride. ) to gel,
Next, the side tube part is immersed in a paste sol (referred to as sol B) containing 95% by weight of dioctyl phthalate based on 100% by weight of polyvinyl chloride to gel it, and then the mold is cured to form it into one piece. You can let me. In this way, a blood bypass tube having a side tube with a communicating inner surface can be integrally molded. The blood bypass tube used in carrying out the present invention may be made of an elastic polymeric material, and flexible materials such as soft polyvinyl chloride or polyurethane are particularly preferred. In this case, so-called flexible polyvinyl chloride, which is composed of polyvinyl chloride and a plasticizer composition, is particularly suitable. In this case, the amount of plasticizer mixed is
The amount is preferably 40 to 100 parts by weight, more preferably 50 to 90 parts by weight per 100 parts by weight. The plasticizer used is dioctyl phthalate,
Known polyvinyl chloride plasticizers such as dioctyl adipate are widely used. The polyvinyl chloride may also contain suitable known stabilizers, such as non-toxic calcium-zinc organic complexes. It is preferable to use polyvinyl chloride having a degree of polymerization of 500 to 2000. The polyurethane used as the material of the present invention can be broadly classified into polyether polyurethane and polyester polyurethane, and both can be used. Molding powder using these polyurethanes may be crosslinked to increase its mechanical strength. The proportion of the crosslinking agent is preferably 0.01 to 5% by weight, and 0.1 to 3% by weight based on the total amount of polyurethane components.
% by weight is more preferred. Further, the preferable range of heat treatment temperature is 60 to 150°C, more preferably 80 to 150°C.
120°C, even more preferably 80-110°C. The blood bypass tube of the present invention has an inner diameter of 8 mm to 30 mm at its thickest portion, and an inner diameter of 1.0 mm to 10 mm at the tips of both ends. The above diameter range is determined depending on the variety of blood vessels. With this setting, the operator can freely cut the tube with scissors or the like to obtain a tube with a desired tip diameter. The cannula membrane wall has a thickness of 0.3 to 3 mm, and may be partially or entirely reinforced with a metallic spiral if desired. Items reinforced with metallic spiral springs have the advantage of not kinking even when bent. Also, the total length of the blood tube of the present invention is 100 mm to 300 mm.
The inner diameter of the side tube is preferably 1 mm to 5 mm. If it is thinner than 1 mm, it will be difficult for the bubbles to come out, and if it is thicker than 5 mm, there is no point in creating a blood stagnation area, which may lead to thrombus formation, which is not preferable. Note that if the total length is outside the above range, it is too long or too short to be practically usable. When the material of the present invention is polyurethane, the dip method is suitable for molding. In the dip method, a mold of a predetermined shape (metal mold, wax mold, epoxy resin mold, etc.) is first made, then treated with polysiloxane to facilitate mold release if necessary, and then treated with a polyurethane solution (usually Concentration 10-30% by weight)
The process of immersing the mold in water and drying it is repeated to form a coating on the mold to form a predetermined thickness, and then the molded product is released from the mold and molded. If the mold is made of wax, you can melt the wax out. Further, the inner surface of the vascular bypass tube can be coated with an antithrombotic material as described above to impart antithrombotic properties. Preferred antithrombotic materials include polyurethane or compositions having polyurethane as a continuous phase and polysiloxane as a separate phase. As an example of the latter, fine particles of polysiloxane are dispersed in a polydimethylsiloxane-polyurethane block copolymer or a polyurethane solution, and the surface of the fine polysiloxane particles, that is, the interface between the polyurethane and the fine particles, is formed by crosslinking of the surface of the fine polysiloxane particles. Particularly preferred are stable emulsions in which the polyurethane molecules of the sea phase are entangled to form an interpenetrating network structure. The coating may be carried out by bringing a solution containing an antithrombotic material into contact with a predetermined blood-contacting surface and drying it.
At this time, the solvent used in the solution is preferably a polyvinyl chloride or polyurethane solvent or swelling agent, or an organic solvent containing these. In this case, a part of the surface of the polyvinyl chloride or polyurethane is dissolved and mixed with the antithrombotic material, so that they are bonded together and the antithrombotic material is well blended and does not peel off. but,
If the contact time is too long, the polyvinyl chloride and polyurethane will melt, so care must be taken. The taper range (length) at both ends of the blood bypass tube of the present invention can be arbitrarily selected. The taper can also be made harder if desired by soaking the taper in, for example, ethyl alcohol for a period of time to remove the plasticizer. Further, the position of the side tube for air venting is not particularly limited, but it is preferably approximately in the center of the tube. Further, although the angle of the side tube is approximately perpendicular to the length direction of the tube in FIG. 1, this angle can be changed as appropriate. Also, there may be two or more side pipes. Example 2 in Figure 2
It may be appropriately inclined in the direction of blood flow as shown in FIG. This is because it becomes easier to remove the mixed air. After removing the air, just close the side tube with forceps or a clip. The bypass tube shown in Figure 2 differs from the tube shown in Figure 1 in the structure of the side tubes and the taper up to the tips of both ends, which are formed so as to be inclined from the center to both ends. There is. In addition, the diameter of the tube in this example is 15 mm at the thickest part, 3.0 mm at the tips of both ends, and the diameter of the side tube part is 4.0 mm.
mm, and the length was 50 mm. The usefulness and effects of a blood vessel bypass tube having tapered ends at both ends, which is one of the features of the present invention, will be explained. As already mentioned, when performing vascular bypass,
The blood vessels to be cannulated (inserted) vary from person to person and from blood vessel site to site. Needless to say, it is hemodynamically preferable to minimize the pressure drop in the bypass blood vessels. If both ends of the vascular bypass tube are tapered as in the present invention, the surgeon can freely adjust the thickness by looking at the blood vessel to be inserted, and can cut it to the most appropriate thickness. Yes, it can be done (see Figure 1).
The cut may be made perpendicularly to the vascular bypass tube, or may be cut diagonally to increase the area of the cut, depending on the operator's discretion. This can be treated with minimal pressure loss, so the taper at both ends of the bypass blood vessel tube of the present invention is truly useful from the operator's point of view. Although the blood bypass tube of the present invention has been described as integrally molded, it does not necessarily have to be integrally molded. This will be described as Examples 3 and 4 with reference to FIGS. 3 and 4. As shown in Figure 3a, set a T-shaped tube and two tubes with one end tapered, and assemble them as shown in Figure 3b.
It may be formed by This assembly may be performed by the supply manufacturer or by the operator. The feature of this type of assembly is that the surgeon can select and assemble T-shaped tubes with structures such as arbitrary angles and tubes with different taper shapes to meet the optimal conditions, based on the surgical situation. The length can be adjusted by cutting it. It is extremely useful for the operator to be able to make timely judgments and adjust the conditions to the optimum conditions. FIG. 4 shows another assembly type as Embodiment 4. This is T as in Example 3.
This is a case where a separate connector is used instead of the tube itself acting as a connector. In this case, the T-tube is made of a soft component such as polyether polyurethane or polyvinyl chloride with a high content of plasticizer,
A hard material such as epoxy resin may be used as a connector (in this case, if desired, a tie band can be tightened from above to complete the connection). In either case, it is preferable to coat the blood-contacting surface with the anti-thrombotic material described above. At the insertion point of the blood bypass tube of the present invention, since the outer surface of the tube also comes into contact with blood, it is preferable to treat the outer surface of the tapered portion from the tip of the tube and a portion of the outer surface from the tapered portion toward the center with an antithrombotic material. . In addition, the already explained figures 1, 2, and 3
A blood bypass tube as shown in Figures 1 and 4 was made, and the antithrombotic materials shown in Table 1 were applied to the inner surface of the tube and the outer surface of the taper, and the aorta was bypassed using an adult dog. After a period of time, each was removed and the results of each were examined. As a result of these results, no thrombus formation is observed, and this tube for vascular bypass is extremely useful from a practical point of view. In addition, even during bypass, the tip of the tube could be adjusted appropriately to match the blood vessels of the aorta.
Since the insertion could be performed optimally and the length could be adjusted under appropriate conditions, there was no problem during use.

[Table] In addition, as a comparative example, when bypass surgery was performed using a tube without side tubes, it was difficult to completely remove the trapped air, and the surgical method was judged to be problematic.

[Brief explanation of drawings]

1 to 4 are perspective views showing embodiments of a blood bypass tube according to the present invention.
Fig. 1 is a perspective view showing the first embodiment, Fig. 2 is a perspective view showing the second embodiment, Fig. 3a is an exploded perspective view before assembly showing the third embodiment, Fig. 3 4b is a perspective view after assembly, FIG. 4a is a partial exploded sectional view of the fourth embodiment before assembly, and FIG. 4b is a partial sectional view after assembly.

Claims (1)

[Claims] 1. Both ends of a tube made of a flexible polymeric substance are tapered toward the tip, and the tube has at least one side tube that communicates with the inner surface of the tube. A blood bypass tube characterized in that it is provided with a blood bypass tube.