JPS6145769A - Sac shaped blood pump - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a blood pump device for an artificial heart, and more particularly to an improvement in a sack-type blood pump driven by gas pressure.

(Prior Art) In recent years, progress has been made in the development of artificial hearts for supplementary and temporary replacement of the functions of the heart outside the body during targeted surgeries and other surgeries.

Research into a sac-type artificial heart powered by gas pressure is being conducted in Japan ahead of the rest of the world, but the path to actual clinical application for patients has only just begun.

The problem in clinical use is the problem of thrombus formation inside the artificial heart, and how to impart antithrombotic properties.
Considered to be an extremely difficult problem, the pump material, design,
It is thought that the smoothness of the surface, as well as problems with blood flow and turns within the blood chamber, are involved in a complex manner.

The present invention was developed with particular attention to the deformable behavior of a sac-type blood pump and the flow of blood within a blood chamber.

Figures 1 to 4 show the basic form of the conventional sac-type blood pump and blood chamber, and Figures 5 and 6 show the deformation of the blood chamber as the air pressure is adjusted. It is something.

The sack-type blood pump is composed of a pressure-resistant (for example, made of polycarbonate) outer case 1 and a blood chamber 2 that is shaped like a flat bag and has an arcuate bottom. In the upper part of this blood chamber 2, a blood inlet pipe 3 and a blood discharge pipe 4 are formed upward and approximately parallel to each other, and a flange 5 is attached around the upper part. Although not shown, the blood inlet tube 3 and the blood outlet tube 4 are equipped with known valves to prevent backflow of blood. The collected blood is discharged from a blood discharge tube 4.

The blood chamber 2 is housed in the Hau Nong outer case 1 under the condition shown in FIG. 1, and is held airtight by a flange 5. Then, through the port 11 provided on the bottom side of the housing outer case 1, the pressure inside the housing outer case is alternately made positive and depressurized, whereby the volume of the blood chamber is alternately reduced and increased. It functions as a pulsating pump.

The present invention was developed by examining various conditions for the formation of thrombi in the blood chamber 2 in animal experiments using the sac-type 9-stroke artificial heart as described above. This was the result of an attempt to develop a possible blood pump.

(Problems to be Solved by the Invention) According to the frugality of the present inventors, the location where thrombi occurs is generally determined in animal experiments under low pumping conditions; It was found that a lot of thrombus occurred at the bottom of 2, especially on both sides near the bottom.

The present inventors further studied and observed the causes of this phenomenon, and found that in areas where blood flow is relatively fast, the formation of thrombus is extremely small, but in areas where blood flow stagnates to some extent, I also learned that there is a high possibility of developing a blood clot. This is because the vicinity of the conduit is where blood naturally flows in and out, and the flow of blood is fast, resulting in less thrombus formation.

On the other hand, near the bottom of the blood chamberer 2, blood tends to accumulate and drain.

The inventors of the present invention have finally arrived at the present invention after conducting various studies to eliminate as much as possible the stagnation of blood near the bottom of the blood chamber 2 where blood tends to stagnate as much as possible. The thickness of the peripheral wall in the blood chamber 2 was approximately uniform as illustrated in FIGS. 3 and 4. When such blood channels 2 are compressed by air pressure in the housing outer case 1 shown in FIG. 1, the volume decreases from (1) to (11) in FIG. It expands as shown in Figure 5 (2) by reducing the pressure of the air.

FIG. 5(1) shows the state of change when air pressure is applied within the housing outer case 1 to the unloaded state shown in FIG. According to this, the volume reduction in the blood chamber 2 does not occur uniformly depending on its cross-sectional shape, but is most likely to change, that is, near the bottom slightly from the center of both wide-area side surfaces of the blood chamber 2. Changes occur preferentially from , and under such changing conditions, a decrease in volume due to an increase in pressure propagates to the surroundings. Then, when the button is pressurized again, Fig. 5 (I[)
As shown in , the parts that are most susceptible to change first touch each other;
This contact sequentially spreads vertically and horizontally. As a result, the blood in the upper part is directly pushed out toward the blood discharge tube 4, but the blood in the lower part tends to accumulate in the side parts. The degree of blood retention in the vicinity of the bottom portion and on both sides of the bottom portion is greater than in the central portion where both side walls contact each other and collapse due to compression. Furthermore, when the pressure inside the housing outer case 1 is reduced and the volume expands as shown in FIG. 50, this portion is not easily replaced with blood newly introduced at each pulsation.

In fact, as a result of animal experiments, thrombus formation is often observed in the areas indicated by the cross lines in Figure 2.

Therefore, in order to suppress the formation of blood clots,
It has been found that when the blood chamber 2 is compressed, it is best to collapse the bottom part and both sides so that no unattached parts remain. In particular, when the volume of the blood chamber is reduced by compression, the reduction occurs from near the bottom, and at the same time both sides of the blood chamber (opposed narrow-area sides) are smoothly compressed, which then propagates upward uniformly. We found that the volume compression pattern is important, and we formed a ridge angle in the longitudinal direction of the bottom on at least one part of the bottom surface of the blood chamber, and made the wall thickness of the ridge line part along the ridge angle larger than that of other parts. It was anticipated that this objective could be achieved by forming the material thinner, and the proposal was already made (Japanese Patent Application No. 42,980/1983).

Although the intended purpose was achieved by the invention, the present inventors carried out a detailed long-term function for further long-term use, and found that the thickness of the ridgeline part of the bottom surface was made thicker than other parts. It has been learned that thinner parts are more likely to suffer from deterioration in strength due to repeated fatigue. Therefore, the present inventors conducted various studies to completely improve the mechanical weaknesses of the bottom surface without changing the blood iR pattern in the blood chamber, that is, to prevent the collected liquid from accumulating on and near the bottom surface of the blood chamber. The shape of the ridgeline portion of the bottom of the thin liquid chamber is a special shape, more specifically, it is thick-walled with a substantially triangular cross section, and preferably, this is achieved by making the bottom of the thin liquid chamber have a predetermined radius of curvature. The problem has been solved and the present invention has been arrived at.The gist of the invention is to provide a TFN liquid inlet tube and a blood discharge TI3 tube each with a built-in valve, and to form a flat-shaped blood tube connected to these tubes. In a sack-type blood pump having a chamber, at least a part of the bottom surface of the blood chamber has a ridgeline formed in the longitudinal direction of the bottom surface, and the ridgeline portion is formed to have a thick triangular cross section. Related to blood pumps.

(Means for Solving the Problems) Next, the present invention will be explained in detail with reference to embodiments shown in FIG. 7 and subsequent figures. Note that the same parts as in the basic form shown in FIGS. 1 to 6 are denoted by the same reference numerals, and detailed explanations will be omitted.

FIG. 7 is a front view of the blood chamber 2 seen from the wide-area side surface 2a, and the bottom end of the bottom surface 2b is formed into a substantially isosceles triangular shape and thicker than other parts, as shown in FIG. It is. This part spans the entire bottom surface from FIG. 7a to g, and a ridge line is formed continuously in the longitudinal direction of the bottom surface,
The range is between 5 and 1. J 7j may be even shorter and limited to between 0 and 8. However, it is preferable that the bottom portion is smaller than the maximum width of the blood chamber 2, more preferably , the width D' is 0.9D smaller than that of the bottom part. ) may be formed.

In addition, the bottom ridge of the blood chamber typically has a pulsation rate of 60
Since it is performed at ~100 times/minute, it is performed about 100,000 times a day, about 3 million times a month, and nearly 40 million times a year, and the bending and stretching movements are performed at each pulse. Therefore, over a long period of time, strength deterioration due to repeated fatigue is more likely to occur, and improvements are needed for this purpose.At the same time, it is also necessary to improve the retention of blood at the bottom of the body at the same time as improving this strength deterioration. Ru.

The present invention improves strength deterioration due to repeated fatigue by making the ridgeline part of the bottom of the blood chamber thicker than other parts, and also improves blood retention by making the thick part as shown in Figure 8B. By configuring the chamber to have a triangular cross-sectional shape as shown, and by setting the shape to a specific condition and preferably the radius of curvature of the bottom of the blood chamber to a predetermined condition, it can be used for a long period of time and has a structure that allows blood to accumulate easily. It was also successfully improved. That is, the present invention aims to improve the blood retention at the bottom part similar to the one already proposed in the above-mentioned -fc (Japanese Patent Application No. 56-42980) using a blood chamber formed by thinning the wall thickness of the ridge line part. Moreover, it is intended to improve the strength of the blood chamber due to repeated fatigue.

The structure of the thick portion according to the present invention will be explained based on FIG. 8B. FIG. 8B is a fully enlarged cross-sectional view of the thick portion at the bottom end (the portion surrounded by the dotted line in FIG. 8A) in FIG. 8A. As shown in the figure, the ridgeline portion 6 of the blood chamber 2 has a maximum thickness ti.

The thickness t is required to satisfy the condition z(t(5z). Here, t is formed by the shortest distance between the bottom end m of the inner wall surface of the blood chamber and the outer wall surface of the blood chamber. In addition, t refers to the maximum thickness formed by the longest distance between the above m and the outer wall surface of the blood chamber. If t is smaller than t, the blood chamber will not be thick. When it is crushed, it forms the most severe bending angle, and as the pulsation rate increases, recovery from the elastic deformation is delayed, and the next deformation is applied before the stretched part has fully recovered. If the number 9 is easily inserted, a problem will arise in long-term use.Even if it is larger than t'i5t, the effect of the present invention cannot be expected as much as the thickness, and it will warp, causing problems in terms of form.

Further, it is preferable that the radius of curvature R of the bottom end of the inner wall surface of the narrow side surface of the blood chamber as shown in FIG. 8A is larger than the radius of curvature r of the bottom end of the outer wall surface.

The radius of curvature of R is 2 to 25, and r is 1 to 2.
It is preferable that it be formed in the range of 0. If R or r is less than the above range, the periphery of the bottom of the leprosy fluid chamber becomes too flat, and if it exceeds the above range, it becomes difficult to bend the blood chamber, both of which are undesirable. Further, the thick cross section of the ridgeline portion needs to be formed in a triangular shape as shown in the figure.

This is because if the shape is other than triangular, the repeated expansion and contraction operations due to pulsations at the bottom of the blood chamber will not proceed smoothly. Note that it is preferable that the bottom end of the triangular outer wall have a radius in order to alleviate stress concentration.

In addition, in order to have excellent bending and stretching durability and to produce an ideal blood flow/pattern during use, the overall shape of the sac must be flat. The ratio D/W of the maximum thickness W in the no-load state shown in FIG. 3 is 1.5 to 3.0, preferably 1.6 to
2.5, more preferably 1.8 to 2.3.

Further, it is preferable that the ratio between the total height on the center line of the blood chamber 2 and the maximum width is 0.8≦D/L≦2.0.

In a blood chamber that satisfies these conditions, the pattern of crushing due to air pressure can be made constant for each beat.

Figure 10 (4) shows an example in which the wall thickness of the blood chamber is thinned and tapered because the ridge angle on the inner wall surface of the blood chamber is formed at an angle of 50°. The thickness of the two surfaces 2b' and 2b' is gradually thinner toward the bottom end, and the ridgeline portion 6
In the section where it becomes, the cross section is formed into a thick triangular shape. As a result, the ridgeline portion is easily compressed by external pressure, and the local strain applied to the ridgeline is absorbed by the triangular thick portion and is relaxed, resulting in excellent fatigue resistance. The two surfaces 2b', 2b' will very easily come into close contact with each other due to external pressure. The first sack-type blood pump having the blood chamber of this example as shown in [21] was used three times/
A one-year accelerated fatigue test was conducted in seconds, but no damage was found. In addition, the film thickness of the blood chamber in this example is 2. (1+mn, the minimum thickness is 1.3 mn, and the maximum wall thickness of the ridge line is 1.8
It was So. The radius of curvature R of the bottom end of the inner wall surface of the blood chamber was 8, and the radius of curvature r of the outer wall surface was 4.

Next, the example shown in FIG. 10(B) is an example in which the ridge angle on the inner wall surface of the blood chamber is as large as 100°, and the blood chamber part film thickness is gradually thinned until it reaches the bottom ridge line. This is an example of a thicker part. The method of tapering the film thickness as described above has been proposed by the present inventors in Japanese Patent Application No. 54)-186562, Japanese Patent Application No. 56-42980,
The method proposed in Japanese Patent Application No. 59-99825 can be used. In order to make the ridgeline part of the present invention thick in a triangular shape,
A method already proposed by the present inventors, patent application No. 175-1982
In the slush molding method shown in No. 257, this can be achieved by making the ridgeline part of the mold used thicker and increasing the heat capacity of this part.

The ridgeline portion of the bottom surface in this example can further extend from the bottom to the opposing narrow-area side surfaces of the blood chamber, if desired. In this way, when the blood chamber 2 is compressed by air pressure, the volume pressure is uniformly flattened from the bottom and the compression propagates upwards of the chamber.
You can get the pattern.

Furthermore, in the present invention, the bottom part of the blood chamber 2 does not necessarily have to be compressed with the highest priority; contact occurs first in a part of the opposing wide-area surfaces, and at the same time, compression also occurs from the bottom part and propagates to the top. However, the entire blood chamber may be collapsed. In this case, a concave part may be provided inward on the large area surface, and the wall thickness may be made thinner. Even in this case, the ridgeline portion is easily deformed, so the entire surface may be easily crushed. become.

In any case, the feature of the present invention is that it has the ability to essentially collapse the lower half of the blood chamber from near the bottom, and has improved durability throughout, making it a high-quality product that can safely withstand long-term use. By imparting bending and stretching resistance, this material made great strides toward practical use as an artificial heart. This makes it possible to withstand long-term use and to minimize the accumulation of blood at the bottom of the blood chamber.

FIG. 11 is a model illustrating the compressive deformation state of the blood chamber 2 in order. When air pressure is applied in the housing outer case to the unloaded state shown in FIG. 8, first ( 1) As shown in the figure, the bottom end begins to deform along with the central part of the wide-area side surface 2a that has no support on both sides. When air pressure acts on the equations, their deformation progresses to the state shown in Figure (II), and finally the wide area side surface 2a
There are two surfaces 2b' and 2b' near the center of ? '1
? 11 As a result, the state shown in (2) is reached.

As a result, the unattached areas near the bottom and on both sides of the bottom, which tend to occur in conventional structures, are minimized, and blood stagnation occurs frequently. In the meantime, using a sac-type artificial heart using a blood chamber 2 formed with a triangular thick wall according to the present invention as shown in FIG. 8, the whole heart of a goat was removed and replaced as a complete artificial heart, and a test was conducted. However, even after using it for 226 days, the pump functioned without any problems.
D=60mm, W=23sn, maximum film thickness 2.1mm,
taX is the minimum film thickness. There was 4 pus, and the thickness of the ridge was 1.9 mm. Further, the radius of curvature R of the inner wall surface was 7, the radius of curvature r of the outer wall surface was 5, and the pulsation conditions were 90 times/min.

The blood chamber part 2 and the blood introduction and discharge pipes 3 and 4 used in the present invention, that is, the parts that come in contact with blood, can be made of a polymeric elastic material, such as soft polyvinyl chloride or polyurethane. is particularly good. In this case, the soft polyvinyl chloride may be molded with a so-called polyvinyl chloride paste consisting of polyvinyl chloride and a plasticizer composition.

In this case, the amount of plasticizer mixed is preferably 40 to 100 parts by weight, more preferably 50 to 80 parts by weight, based on the polyvinyl chloride. stabilizers, such as non-toxic calcium
It may also contain a zinc organic complex or the like. It is preferable to use polyvinyl chloride having a degree of polymerization of 500 to 2,000.

The polyurethane used as the material in this example can be roughly divided into polyether polyurethane and polyester polyurethane, and both can be used, but polyether polyurethane is preferable from the viewpoint of elastic properties and fatigue resistance. Preferably 0. Molded products using these polyurethanes may be completely crosslinked in order to enhance their mechanical strength.

Polyester-based polyurethane (Ma) is a hard elastomer with high elastic modulus, high tear strength, and is suitable for forming conduit sections and flanges.

The ratio of crosslinking agent is 0.0 to the total amount of polyurethane components.
It is preferably 1 to 5 weight ratios, and more preferably 01 to 3 weight ratios. Further, the preferable range of heat treatment temperature is 60 to 1
The temperature is 50°C, more preferably 80 to 120°C, even more preferably 80 to 110°C.

Furthermore, the wall thickness of the blood chamber part 2 used in the present invention is as follows:
When the blood chamber part 2 is made of soft polyvinyl chloride with a plasticizer content of 50 to 80 parts by weight, the plasticizer content is between 0.3 and 20 at the thinnest part due to its repulsion characteristics and fatigue resistance. is preferable, and more preferably 0.6 to 1.6 mm. Further, when the blood chamber 2 is made of polyurethane material, the wall thickness is preferably 0.2 to 1.5 mm;
A tone of 0.5 to 1.0 is more preferable. If this thickness is too large, the operation timing of the blood chamber 2 will be delayed or the deformation time will be prolonged when the inside of the outer case 1 is pressurized or depressurized. response characteristics cannot be obtained. On the other hand, if this wall thickness is too thin, the deformation behavior of the blood chamber becomes sensitive, making it difficult to control and causing a decrease in cyclic fatigue strength.

In the artificial hexagon of this embodiment, its compatibility with blood can be improved by coating its blood contact surface with a substance having excellent antithrombotic properties. For example, polyether segment) yJ? Surface treatment with Riurekun,
Polyether polyurethane-polydimethylsiloxane'ff: Coating treatment with an antithrombotic substance as a component may be performed.

As the molding method used in carrying out the present invention, a wide range of known molding methods can be applied.

Examples of these methods include injection molding, casting molding, and roast wax methods.

When molding the present invention using polyvinyl chloride plastisol, the following method may be used. First, a heated molding mold is immersed in plastisol, or plastisol is placed inside the mold, and the heat of the molding mold dulls the portion of the plastisol in contact with the mold. Since the thickness of the dulling layer can be adjusted by the heat capacity of the mold,
The wall thickness of the ridgeline portion can also be arbitrarily determined by locally increasing the thickness of the portion corresponding to the ridgeline of the molding die and adjusting the heat capacity. Further, the present invention may be carried out by adhering a linear substance made of the same material or a different material to this ridgeline portion.

(Effects of the Invention) As described above, the present invention thickens the ridgeline portion of the bottom surface of the blood chamber in the longitudinal direction so as to have a substantially triangular cross-section, thereby eliminating bending resistance and reducing the resistance during bending and stretching. This relieves stress and propagates the volume reduction due to compression from near the bottom upwards, ensuring tighter contact at the bottom, so there is almost no blood stagnation.
Demonstrates excellent durability and prevents blood clots. Further, in terms of structure, since only a predetermined thick portion is formed on the bottom surface, the processing process is simple and the basic form can be used to its fullest extent.

[Brief explanation of the drawing]

The drawings illustrate the sack-type blood pump according to the present invention, in which Fig. 1 is a perspective view of the blood chamber housing outer case having a basic configuration, Fig. 2 is a front view of the blood chamber, and Fig. 3 is a perspective view of the blood chamber housing outer case. Its side view, FIG. 4 is its cross-sectional plan view, and FIG. The figure is a sectional view taken along the line X-X in FIG. , FIG. 8B is an enlarged view of the bottom end portion in FIG. 8A, and FIG. 9 is a sectional view taken along the line 11-1 in FIG.
Figures (A) and (B) are vertical sectional side views of the bottom of the blood chamber showing the angle of the ridge and the thin state of the blood chamber, and Figure 11 is the blood chamber? It is a side view which shows the deformed state of - in order by longitudinally cutting a bottom part. In the figure, numeral 1 indicates a housing outer case, and 2 indicates a blood chamber. Applicant Zeon Corporation Figure 2 Figure 3 Figure 5 (I) (I[) (m) 6th Figure 7 Figure 8A Figure 10 (A) (B) (I) ( 1) (m)

Claims (1)

[Scope of Claims] 1. A sack-type blood pump comprising a blood inlet pipe and a blood discharge pipe each having a built-in valve, and having a flat blood chamber formed in communication with these pipes, wherein the blood A sac type blood pump characterized in that at least a part of the bottom surface of the chamber has a ridgeline formed in the longitudinal direction of the bottom surface, and the ridgeline portion is formed to have a thick triangular cross section. 2. The thick portion satisfies the condition l<r<5l between the maximum thickness t and the minimum thickness l formed on the bottom end of the inner wall surface of the blood chamber and the outer wall surface of the blood chamber. A blood pump according to claim 1, comprising: 3. The radius of curvature R of the bottom end of the inner wall surface of the narrow side of the blood chamber is configured to be larger than the radius of curvature r of the bottom end of the outer wall surface, and R is in the range of 2 to 25 and r is in the range of 1 to 20. A blood pump according to claim 1, comprising: 4. The ratio of the maximum width D of the wide-area side surface of the blood chamber to the maximum width W of the narrow-area side surface in an unloaded state, D/W is 1.5 to 3.
．． 0. The blood pump according to claim 1, wherein the blood pump is 0. 5. The blood pump according to claim 1, wherein the blood chamber is made of soft polyvinyl chloride or polyurethane.