JPH0416676Y2 - - Google Patents

Description

[Detailed description of the invention] A. Field of industrial application The present invention relates to a cannula, particularly a cannula for cardiac surgery.

B. Prior Art In recent years, progress has been made in the development of artificial hearts for auxiliary and temporary replacement of the functions of the heart outside the body during open-heart surgery and other surgeries. For example, as shown in FIG. 7, for example, a sac-type blood pump device 11 is connected between the right atrium and the pulmonary artery of the living body's heart 10, and between the left atrium and the aorta.
Such a blood pump device has already been put into clinical use as an auxiliary heart.

Such a blood pump device 11 is called a sack type, and mainly includes a pressure-resistant (for example, made of polycarbonate or polyurethane) housing outer case 1 and a flat bag-shaped housing case 1 that is airtightly housed inside the housing outer case. It consists of 2 blood chambers of the sac type. At the upper part of the blood chamber 2, a blood introduction tube 3 and a blood discharge tube 4 are formed upwardly and substantially in parallel to communicate with the blood chamber. A flange portion 5 forming a part of the housing is provided around the upper portion of the blood chamber portion, and the blood chamber is hermetically housed within the housing outer case 1 by this flange portion. In addition, artificial check valves 6 and 7 are installed inside each of the blood introduction tube 3 and the blood discharge tube 4 to prevent the blood 17 from flowing back. The blood 17 introduced therein is pumped out from the blood discharge tube 4. Blood is pumped out by alternately introducing and discharging fluids, such as compressed air and decompressed air, through the port 8 provided at the bottom of the housing outer case 1. This is done by repeatedly expanding and contracting.

Here, the blood pump 11 and the living body are connected through conduits 12 and 13 called cannulae. For example, for the left heart, blood cannula 1
2 is connected to the aorta by an anastomosis, and the blood removal cannula 15 is inserted into the left atrium and fixed to the living heart with a tobacco suture. Each cannula 12, 15 and each blood conduit 3, 4 on the blood chamber 2 side are inserted from both ends of each connector 13 to the position of a ring-shaped flange 14 provided at the center thereof.

The inner diameter of these cannulae should be large in order to transport a sufficient flow of blood. however,
If the inner diameter of the cannula is increased, the outer diameter must also be increased, but when the cannula becomes thicker in this way, the invasion of blood vessels and the heart of the living body increases when connecting the living body. Therefore, for a living body, it is better for the outer diameter of the cannula to be as small as possible. In addition, in order to conform to the living body and not injure the living body, it is desirable that the material be made of as soft a material as possible.

From the above, it is necessary to make the cannula thinner, and this requirement is particularly noticeable when the cannula is for children or infants. However, due to the thinning of the cannula, the shape retention and mechanical strength of conventional cannula materials (such as soft polyvinyl chloride) decrease, and the tip portion sometimes breaks or collapses due to external force. For this reason, the thinned cannula, especially the cannula 15 on the blood removal side (the side that draws blood from the living body and is subjected to negative pressure), is made of reinforcing material such as a coil of metal wire wound spirally. It is necessary to enter it as

However, in this case, since the cannula is made thinner, the entire coil or its tip is likely to be exposed to the inner or outer surface of the wall of the cannula main body. This not only does not provide the intended reinforcing effect, but also damages the antithrombotic agent applied to the surface (particularly the inner surface) of the cannula, causing thrombus formation. In addition, in such a situation, the sharp tip of the metal wire may injure the operator himself or herself during operation and may cause infection from the patient.

Therefore, physical properties such as elasticity of the material impose limitations on the diameter and size of the cannula, making it impossible to obtain a product with the desired thin wall thickness.

C. Purpose of the invention The purpose of the invention is to create a cannula that effectively reinforces the cannula to give it sufficient strength, improves reliability, and reduces flow resistance (reduces pressure loss, increases flow rate) by thinning the wall. Our goal is to provide the following.

D. Structure of the invention That is, in the present invention, the side to be inserted into the living body is a small-diameter tube part, and a coil-shaped reinforcing material is embedded in at least this small-diameter part so as to surround the blood flow path. The present invention relates to a cannula in which a cross section of the reinforcing material cut on a center line in the transverse direction is flat in a direction along the center line.

E. Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 to 6.

FIG. 1 shows a cannula 25 according to a first embodiment.
This shows that. This canyule 25 itself is
Like the cannulae 12 and 15 in FIG. 7, it is connected to the heart (atrium, ventricular wall, etc.) or blood vessel wall of a living body by an anastomosis technique. Here, canyule 25
Although this will be exemplified as a blood removal cannula, it may be similarly configured as a blood delivery cannula.

The region of the cannula 25 that is inserted into a living body such as the living heart described above is a small diameter tube portion 25a, and a blood flow path 20 is formed in this small diameter tube portion 25a.
Metal coil 2 as a reinforcing material surrounding the
6 is buried. Here, the entire cannula 25 is made of a soft polyvinyl chloride main body, and the metal coil 26 may exist over a necessary length range from the tip in the small diameter tube portion 25a, 27, 28 (Fixing or bonding to the living body by tobacco suture is performed in the area between these brim parts to prevent the insertion part from coming off.), especially buried outside the brim part 28 (external side) It is desirable that

The metal coil 26 is made of stainless steel such as SUS, and has a cross section along the center line 21 in the longitudinal direction of the cannula (i.e., the cross section shown in FIG. 1) that is flat in the direction along the center line 21 (in this example Therefore, the thickness in the direction perpendicular to the centerline direction is considerably thinner.
As clearly shown in FIG. 2A, the cross-sectional size of the coil 26 is width w ₁ and thickness t ₁ , where w ₁ >t ₁ , especially w ₁ =(1.2~
10) It is best to set t ₁ , for example w ₁ = 0.45mm, t ₁ =
Set to 0.14mm. At this time, cannula small diameter tube part 2
The wall thickness x ₁ of 5a can be easily reduced to 0.6 to 1.5 mm, for example, 1.4 mm.

On the contrary, the conventional metal coil 16 with a circular cross section
Now, assuming that the same strength and ease of molding are to be obtained, the diameter R of the cross section has the same width and thickness, for example, 0.25 mmφ, as shown in FIG. Wall thickness x ₂ is 2.0~3.0
mm, for example 2.5 mm. Therefore,
In the conventional method, the cannula inner diameter R ₁ is 8 to 10 mm, but when a coil 26 with a plate-shaped cross section is embedded,
When the outer diameter R ₀ of the cannula shown in FIG. 1 is set to 3 to 20 mm, for example 14 mm, the inner diameter R ₁ of the cannula can be significantly enlarged compared to the case of the conventional coil 16 having a circular cross section. In other words, the wall thickness x ₁ of the small diameter tube portion 25a can be made smaller than the conventional x ₂ (X ₁ <x ₂ ), especially when x ₁ ≦
Since it can be made as small as 0.5 x x ₂ , the cannula inner diameter R ₁ can be made larger (for example, 11 to 12.8 mm, specifically 2 mm or more), and the cannula wall thickness x ₁ can also be made smaller. This makes it possible to make the wall thinner.

As mentioned above, by embedding the flat coil 26, the coil itself can exert a cannula reinforcing effect and improve its strength and reliability against kinking (bending phenomenon) and deformation. In addition, by flattening the cross section, it is possible to thin the cannula as described above while maintaining the strength as a coil, increasing the inner diameter → reducing flow resistance, reducing pressure loss, and ultimately increasing blood flow or stroke volume. . In particular, when using the cannula for blood removal, the tip side tends to collapse under negative pressure.
With the cannula of this embodiment, it is possible to simultaneously increase the strength and increase the flow rate, two requirements that could not be met in the past. Furthermore, the wall thickness x ₁ is sufficient to embed the coil 26, and the coil 26 will not be exposed and damage the antithrombotic agent coating on the inner surface of the cannula or injure the operator.

Further, the cannula small-diameter tube portion 25a is soft, and the inner diameter can be increased and the outer diameter can be reduced at the same time, so it has great usability and is suitable for infants and the like.

In addition, since the coil 26 is buried outside the second flange 28, the fixation by tobacco suture performed between the first flange 27 and the second flange 28 is not affected by the metal coil 26, and is easily performed. becomes.

The material constituting the cannula 25 is preferably polyurethane or vinyl chloride containing a plasticizer. As the polyurethane, known polyester polyurethanes and polyether polyurethanes are widely used. As the polyvinyl chloride plasticizer, known polyvinyl chloride plasticizers such as dioctyl phthalate and dioctyl adipate are widely used. In this case, the flexible polyvinyl chloride may be formed from a so-called polyvinyl chloride paste consisting of polyvinyl chloride and a plasticizer composition.

Further, in order to improve antithrombotic properties of the cannula 25, the inner surface of the cannula 25 that comes into contact with blood can be coated with a known antithrombotic agent to improve blood compatibility.

The metal coil 26 embedded in the cannula has a plate-like cross section as described above, but its shape may be rectangular as shown in FIG. 3A or elliptical as shown in FIG. 3B. (long axis is center line 21
, the short axis is perpendicular to it), the third
It may be of various types, such as the one shown in Figure C. The term "flat" as used in the present invention broadly includes shapes as shown in FIG. The cross section of the coil is preferably elliptical.

Next, canyule according to this example (product of this invention)
Specifically, when the conventional cannula (conventional product) was used in a pump device as shown in FIG. 7, the results shown in FIGS. 4 to 6 were obtained.

Figure 4 shows that the pump driving pressure is negative pressure (when the pump is expanded:
FIG. 5 compares and shows the blood flow rates obtained when the pump driving pressure is positive (during pump contraction: during blood transfer). According to this,
It can be seen that at any driving pressure, the flow rate of the product of the present invention is significantly increased compared to the conventional product.

Figure 6 shows a comparison of kinking, cannula wall thickness, and ejection volume (where ○ indicates good, △ indicates slightly poor, and × indicates poor). Even if one of the inner diameters is changed to reduce the wall thickness, there will be no kinking and the coil will not be exposed, and especially if the inner diameter is enlarged, the stroke volume will be sufficient.

Although the present invention has been illustrated above, the embodiments described above can be further modified based on the technical idea of the present invention. For example, the above-described coil 26 may be buried in other areas, or the buried position may be varied.

F. Effects of the invention As mentioned above, this invention embeds a reinforcing material in the shape of a coil with a flat cross section in the small diameter tube of the cannula, so it exerts the cannula reinforcing effect and improves its strength and reliability against kinking (bending phenomenon) and deformation. In addition, by flattening the cross section, it is possible to thin the cannula as described above while maintaining the strength of the coil, increasing the inner diameter → reducing flow resistance, reducing pressure loss, and ultimately increasing blood flow or It can increase stroke volume. Therefore, it becomes possible to simultaneously satisfy two demands that were not compatible in the past: increasing the strength and increasing the flow rate. Moreover, the wall thickness is sufficient to embed the coil, and the coil will not be exposed and damage the antithrombotic agent coating on the inner surface of the cannula or injure the operator.

[Brief explanation of the drawing]

1 to 6 show an embodiment of the present invention, in which FIG. 1 is a half-sectional view of the main part of the cannula, FIG. 2A is an enlarged view of a part of FIG. 1, and FIG. 2B is an enlarged view similar to Fig. 2 A of the conventional product, Fig. 3 A, Fig. 3
Figures B and 3C are diagrams showing the cross-sectional shape of the coil, Figures 4 and 5 are graphs comparing blood flow rates depending on driving pressure, and Figure 6 is a table summarizing cannula performance. FIG. 7 is a schematic diagram showing how the blood pump device is used. In addition, in the symbols shown in the drawings, 11... blood pump device, 12, 15, 25... cannula,
13... Connector, 16, 26... Coil, 20
...Blood flow path, 21 ... Center line, 25a ... Small diameter tube part, 27, 28 ... Brim part, w ₁ ... Width, t ₁ ...
Thickness, X ₁ , x ₂ ... Wall thickness, R ₁ ... Inner diameter, R ₀ ... Outer diameter.

Claims (1)

[Scope of utility model registration request] The side that is inserted into the living body is the small diameter tube part,
A coil-shaped reinforcing material is embedded in at least this small diameter tube portion so as to surround the blood flow path, and a cross section of the reinforcing material cut on the center line in the longitudinal direction of the cannula is flat in the direction along the center line. Canyule.