JPS622538B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sac-type blood pump for an artificial heart or an artificial lung, in which a blood chamber is alternately compressed and expanded by changes in gas pressure, and a method for molding the same. .

In recent years, progress has been made in the development of artificial hearts and artificial lungs for auxiliary and temporary replacement of the functions of the heart and lungs, for example outside the body, during open-heart surgery and other surgeries.

The present invention provides a blood pump suitable for such artificial hearts and artificial lungs.

Using an artificial heart as an example, for patients with acute myocardial infarction, cardiogenic shock after open-heart surgery, or acute heart failure that resists medical treatment,
It mechanically assists blood circulation, thereby reducing the burden on the heart and increasing the amount of circulating blood flow to maintain blood circulation throughout the body.

FIG. 1 shows an overall view of a conventionally published sac-type pneumatic artificial heart, FIG. 2 shows a valve mounting part, and FIG. 3 shows an exploded view. To explain in detail according to the drawings, the housing includes a cylindrical pressure-resistant housing body 1 having a flat cross section, and an upper lid attached to a flange 8 integrally formed in an upper opening 2 of the housing body 1. It consists of 3. The housing body 1 and the top cover 3 are each made of, for example, a synthetic polymer material.

On the outside of the upper lid 3, there are an introduction conduit 4 for introducing blood and a discharge conduit 5 for discharging blood, which extend approximately parallel to each other.
The check valve 6 of the inlet conduit 4 is set for blood introduction, and the check valve 7 of the discharge conduit 5 is set for blood discharge.

Inside the upper lid 3 is a cylindrical portion 9 with a flat cross section.
is integrally provided, and a bag-like member 11 constituting a blood chamber 10 is fixedly attached to this cylindrical portion 9. That is, the size of the upper opening 12 of this bag-like member 11 is made approximately equal to the external size of the cylindrical portion 9 of the upper lid 3, and this bag-like member 11
The cylindrical part 9 is fitted into the upper opening 12, and this part is attached by gluing. In this way, a blood chamber 10 communicating with both conduits 4, 5 is formed. This bag-like member 11 can be made of an elastic material such as soft polyvinyl chloride or polyurethane, and as shown in FIG. 3, it also has a flat cross section.

A thick portion 13 is provided around the upper opening 12 of the bag-like member 11, and the thick portion 13 is press-fitted into the upper opening 2 of the housing 1. The upper cover 3 is attached to the flange portion 8 of the housing body 1 by adhering or welding by ultrasonic welding or the like. In this case, the upper cover 3 may be attached to the flange portion 8 by screwing.

The conditions required for a blood pump used as such an artificial heart are: (1) The shape essentially fits well with the living body, and (2) It has antithrombotic properties, such as no stagnation points in the blood flow. (3) The resistance of the flow path is low and a sufficient flow rate can be obtained with normal venous pressure. (4) The ventricular volume is well matched to the living body. (6) The constituent materials must be sufficiently durable with little fatigue; (7) The structure must be such that hemolysis does not occur; , and not causing excessive negative pressure within the ventricle.

Air-operated sack-type blood pumps have been attracting attention as a type that satisfies these conditions to a great extent and have extremely excellent functions. However, there is a problem that makes the process extremely complicated.

Conventionally, this sac-type blood pump has a top lid having two conduits arranged approximately parallel to each other, a blood chamber, and a housing that are each molded separately, as shown in the exploded view of FIG. 3 to illustrate the assembly process. It is assembled. The biggest problem with the incense is the point of attachment between the upper lid and the blood chamber.
If the top lid and blood chamber are molded separately and then assembled and glued together, it is substantially difficult to obtain a smooth surface at the point of attachment. That is, as shown in the longitudinal cross-sectional view of FIG. 4, unevenness occurs over the entire circumference due to a step, a notch, or a recess at the contact point between the upper lid 3 and the blood chamber 10. There is no proper way to prevent it. If such a step or recess occurs in the bonded portion, a blood stagnation portion will naturally occur there during use, and blood will inevitably coagulate in that portion. The formation of this blood clot is a fatal defect when used as an artificial heart. In other words, if even a very small fragment of a thrombus gets mixed into the blood, it becomes an embolus and is sent throughout the body along with the blood, causing occlusion in capillaries and embolism in cerebral arteries, resulting in so-called cerebral embolism or cerebral thrombosis. cause. Therefore, all blood contact surfaces from the blood chamber to the conduit must be smooth from the viewpoint of thrombosis prevention.

Conventionally, in order to somehow repair the steps and uneven recesses at the bonding area between the top lid and blood chamber that were inevitable during the assembly of this sac-type blood pump, thermosetting liquid polymers of the same type as the top lid and blood chamber were used. A method of filling with material is used. That is, when the upper lid part and the blood chamber part are made of soft polyvinyl chloride, a method such as pouring polyvinyl chloride plastisol into the recessed part of the contact part and hardening it by heat treatment has been used. However, with this method, it is extremely difficult to uniformly adhere polyvinyl chloride plastisol to the bonded area, and unevenness inevitably occurs in the treated area. As a natural result of the uneven portion, turbulence occurs in the flow of blood, which causes thrombus formation.

The present invention provides a blood pump whose inner surface from the blood chamber to the conduit has a substantially seamless and smooth surface, which was not possible with the prior art, and a method for molding the same.

That is, the blood pump according to the present invention includes an introduction conduit for introducing blood into the artificial heart and a discharge conduit for discharging blood from the artificial heart, and the two conduits are arranged substantially in parallel. and the blood chamber is provided in communication with the conduit, at least the blood chamber is constructed of polyvinyl chloride containing a plasticizer, and the inner surface from the blood chamber to the conduit is substantially seamless (seamless). Among the upper lid and blood chamber, at least the blood chamber is molded from polyvinyl chloride plastisol containing a plasticizer, and the upper lid with the conduit is made of soft plastic. Alternatively, it is made of hard polyvinyl chloride, or polyvinyl chloride containing a plasticizer, and a polymeric material with good thermal adhesion properties, and the bonded portion between the two is made into a substantially seamless and smooth surface.

A method for molding such a heart pump is to use the above-mentioned polymer material for the upper lid and the blood chamber, and mold the blood chamber in contact with the already molded upper lid by a slush molding method using polyvinyl chloride plastisol. This is done by

That is, two conduits arranged approximately parallel to each other are provided, and the upper edge of the mold for the blood chamber is fluid-tightly attached to the upper lid made of polyvinyl chloride containing a plasticizer.
Fill vinyl chloride plastisol in advance or through a tube inserted through the conduit up to a position in contact with the upper lid, heat the mold to form a gelled layer in contact with the mold, and fill the mold with vinyl plastisol through the tube inserted through the conduit. The ungelled plastisol and at the same time the ungelled plastisol that has flowed down from the inner boundary between the lower end of the upper lid and the upper end of the gelled blood chamber are discharged to form the boundary smoothly and seamlessly, and then the mold is heated to gel. The procedure consists of allowing the plastisol to solidify, completely seamlessly integrating the blood chamber into the top lid, and removing the formed blood chamber from the mold.

Hereinafter, the present invention will be explained in detail with reference to Examples. First, a first embodiment will be explained with reference to FIGS. 5 and 6. Using polyvinyl chloride plastisol as a raw material, a top lid portion with a conduit (FIG. 5) is prepared by a dip method using a known method. An annular protrusion may be provided on the conduit portion of the upper lid portion for attaching the valve, or the conduit element to which the valve is attached may be connected later. In any case, the upper lid part requires the upper lid 3 and the two conduits 4 and 5. In this example, a flat cylindrical portion 9 is integrally molded on the inside of the top lid. The upper lid part thus produced is placed in a metal mold 15 prepared in advance so as to fit exactly into the outside of the cylindrical part 9, as shown in FIG. 6A. In this case, the mold 15 is liquid-tightly fitted to the upper lid 3. Next, as shown in FIG. 6B, polyvinyl chloride plastisol (for example, Zeon 131A manufactured by Nippon Zeon Co., Ltd.) is added to the mold 15 up to the portion indicated by the broken line in the figure. Next, it is immersed in a heating bath. In this case, the heating temperature used is 70°C to 150°C, more preferably 80°C to 110°C. When the polymer used for plastisol is not a vinyl chloride homopolymer but a copolymer with a low thermal softening point, such as vinyl chloride-vinyl acetate or vinyl chloride-vinyl ether copolymer, a relatively low temperature may be used. Processing time is preferably from several minutes to 30 minutes. If the heating is insufficient or the treatment time is too short, the gelled layer will be too thin, whereas if the temperature is too high or the treatment time is too long, the gelled layer will be too thick, which is undesirable. The part of the plastisol that comes into contact with the metal mold gels due to the heat.
As shown in FIG. 6C, the gel layer 16 is deposited to a certain thickness. Plastisol also exists inside the cylindrical part 9 integrally molded on the top lid, but the sol in this part is made of thick polyvinyl chloride, which has low thermal conductivity, and the inner surface is made of thick polyvinyl chloride. The plastisol in this part does not gel because it is at a lower temperature than the part in contact with the mold, and therefore, the plastisol in this part naturally flows down in the process of discharging ungelled plastisol through the pipe inserted into the conduit shown in Figure 6D. Due to the surface effect, the blood chamber can be finished with a so-called seamless free surface without any steps. Thereafter, heating curing is performed as shown in FIG. 6E. At this time, the preferred temperature range is 160 to 240°C, more preferably 190 to 210°C. Curing is insufficient at temperatures lower than 160°C, and polymer decomposition may occur at temperatures higher than 240°C.

Thereafter, when the mold is cooled and the mold is released as shown in FIG. 6F, the upper lid portion including the conduit and the blood chamber portion can be seamlessly molded into one piece. Although the present invention may be applied to aqueous plastisols, it goes without saying that it is also applicable to organosols in which the dispersion medium is an organic solvent.

Next, a second embodiment will be explained with reference to FIG. FIG. 7A shows an upper lid part made of epoxy resin, and does not have an annular cylindrical part inside the upper lid part. As in the first embodiment, the slush molding die 15 shown in FIG.
Install the top cover 3 as shown. In this case, the mold is fitted in a liquid-tight manner to the top lid.

Next, polyvinyl chloride plastisol is added to the inside of the slush mold. Plastisol is
As shown in FIG. 7C, the upper lid and blood chamber are added to a position slightly higher than the plastisol portion (indicated by the broken line in the figure). The remaining operations are the same as in the first embodiment. In this case as well, the plastisol in the top lid does not gel due to the insulation effect of the top lid, so when the plastisol is discharged, it freely flows down along the wall surface and is molded into a beautiful smooth surface due to its flattening effect. Ru.

By such a method of the present invention, it is possible to integrally mold a blood pump for an artificial heart made of soft polyvinyl chloride.

By utilizing the present invention, not only integral molding is possible, but even greater technological advances can be expected.

That is, the amount of plasticizer in the polyvinyl chloride can be changed between the upper lid part and the blood chamber part. It is preferable that the upper lid part be rigid. This is because, as shown in FIG. 2, the pressure-resistant housing body is fixed to the upper lid, so it is difficult for anything too soft to stick. In addition, blood pumps are repeatedly pressurized and depressurized from the outside during use.
Due to pressurization and depressurization, the volume of the conduit section changes, and if the internal volume expands or contracts, it may affect the valve mounting section, which could lead to an accident in which the valve comes off.
Therefore, it may be difficult to make the upper lid part too soft. In the case of the present invention, since the upper lid part is molded separately in advance, the amount of plasticizer in the upper lid part is preferably smaller than the amount of plasticizer in the blood chamber part. Therefore, when molding the top lid from polyvinyl chloride plastisol, the polyvinyl chloride plastisol contains relatively little plasticizer, such as polyvinyl chloride 100.
parts, 40 to 60 parts of dioctyl phthalate (plasticizer),
A plastisol consisting of 3 parts of a calcium-zinc organic complex may be used as a stabilizer.

On the other hand, the blood chamber is a portion whose volume changes due to air drive and thereby performs pump operation, and therefore needs to be soft and elastic. A suitable plastisol composition is 70 to 90 parts of dioctyl phthalate to 100 parts of polyvinyl chloride.
part is preferred.

It is also possible to use a top lid made of hard polyvinyl chloride to which no plasticizer is added, or by the method of the present invention, a top lid made of another polymeric material to which the top lid and blood chamber can be bonded can be used. It is also possible to use In this case, the polymer materials used include polyurethane, epoxy resin, and polymethyl methacrylate resin. The upper lid part made of these polymeric materials can be fused and bonded to the blood chamber part made of soft polyvinyl chloride by the method shown in the present invention.

The inside of the integrally molded blood pump is as follows:
The antithrombotic properties of the blood contacting surface can also be improved by coating it with known antithrombotic materials, such as polyurethane-dimethylsiloxane block copolymers.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a sac-type artificial heart blood pump, Fig. 2 is a vertical sectional view of the valve attachment part of the pump, and Fig.
This figure is an exploded view of the pump, FIG. 4 is a vertical cross-sectional view showing a conventional connection between the upper lid and the blood chamber, and FIG. 5 is a perspective view of the upper lid. Figures 6A-F and 7
Figures A to C are explanatory diagrams showing the process of molding the blood pump for an artificial heart according to the present invention, respectively. DESCRIPTION OF SYMBOLS 1...Housing body, 3...Top lid, 4...Introduction conduit, 5...Discharge conduit, 6, 7...Check valve, 9
... Cylindrical part, 10 ... Blood chamber, 15 ...
Mold, 16...Gel layer.

Claims (1)

[Scope of Claims] 1. A sac-type blood pump in which a blood chamber is alternately compressed and expanded by fluctuations in gas pressure, comprising an introduction conduit for introducing blood into the blood pump, and an introduction conduit for introducing blood from the blood pump to the blood pump. An upper lid is provided with a discharge conduit for discharging blood, and the two conduits are arranged substantially parallel to each other, and the upper lid is made of polyvinyl chloride containing a plasticizer and is provided in communication with the conduit. , a blood chamber formed of a flat bag-shaped blood chamber whose inner surface leading to the conduit is seamlessly integrally formed, and a housing body which encloses the blood chamber in the upper lid and is attached in a liquid-tight manner. pump. 2. Two conduits arranged approximately in parallel are provided, and the upper edge of the mold for the blood chamber is liquid-tightly attached to the upper lid made of polyvinyl chloride containing a plasticizer, and a tube in which the conduits have been inserted in advance or Fill the mold with vinyl chloride plastisol to the point where it contacts the upper lid, heat the mold to form a gelled layer in contact with the mold, and simultaneously fill the ungelled plastisol with the lower end of the upper lid through a tube inserted through the conduit. The non-gelled plastisol that has flowed down from the inner boundary of the upper end of the gelled blood chamber is discharged to form a smooth and seamless boundary, and then the mold is heated to solidify the gelled plastisol and completely remove the upper lid. A blood pump molding method characterized by seamlessly integrating a blood chamber into a mold and removing the formed blood chamber from a mold.