JPH0228984B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a new type of cannula, and more particularly to a new form of cannula suitable for cardiac surgery.

Conventionally, a cannula for an artificial heart-lung machine has been used during heart surgery. This type of cannula does not have a flange at the tip as shown in Figure 1a, or it has a flange as shown in Figure 1b.
There is only one that is provided on the outer periphery of the tip part perpendicular to the longitudinal center line of the cannula as shown in FIG.
During cardiac surgery, the insertion tip of the cannula is fixed to the heart wall or blood vessel wall with purse string sutures, etc. However, if the cannula does not have a collar at the tip, the insertion tip can easily fall off, especially when used as an auxiliary artificial prosthesis. When a heart or the like is used, the long-term pulsation of the heart increases the risk of it falling off, which is a fatal problem. Furthermore, when an auxiliary artificial heart is used, it is used for a long period of time, so if a large amount of anticoagulant such as heparin is used, the patient tends to bleed, which is undesirable. For this reason, if the use of heparin is suppressed, blood clots are likely to occur in the blood stagnant portion formed in the suture fixing portion, which also poses a fatal problem.

Even if the cannula is provided with a collar on the outer periphery of the distal end, in the case of the one shown in FIG. The flange 2 provided on the flange does not fit tightly, which causes blood to stagnate in the bulging portion of the flange, causing a fatal problem that can cause blood clots. Also, if you try to force the brim to come into close contact with the heart or blood vessel wall, it will cause a corresponding strain on the heart or blood vessels and the accompanying stress, which will drastically reduce the effectiveness of resting the myocardium using, for example, an auxiliary artificial heart. It will end up being put away.

Furthermore, advances in heart surgery have made it necessary to use a cannula for long periods of time, for example, by using an artificial heart or an auxiliary artificial heart (hereinafter referred to as an auxiliary artificial heart), or to insert the cannula into a curved surface with a large equal curvature on the dorsal side of the heart. and in these cases,
There is also a problem that the conventional cannula described above cannot be used.

The present invention skillfully solves these problems, and is a cannula that facilitates and secures the insertion tip and has a structure that prevents blood from stagnation. A cannula whose part is inclined at a minimum angle of 30° to 80° between a straight line passing between two opposing points on the maximum outer circumference of the collar part and the longitudinal center line of the inner hole of the cannula. Pertains to.

Embodiments of the present invention will be described below based on the drawings.

FIG. 2 shows an embodiment in which the inner diameter is the same over the entire length and the flange is inclined with respect to the length direction of the cannula, which is suitable as a blood removal cannula for, for example, a heart-lung machine.

FIG. 3 shows another embodiment, which is a cannula in which a thin tube that communicates with the insertion tip and a thick tube that seamlessly communicates with the thin tube on the inside and has a larger inner diameter than the thin tube are integrally constructed. This is an embodiment in which the flange is inclined with respect to the length direction of the capillary tube, and is suitable for a blood removal cannula for left ventricular assist. The capillary tube is bent in different directions at points A, B, and C, and a metal spiral is installed in these portions to prevent the kinking phenomenon (bending phenomenon).

As shown in Figures 4a and 4b, the slope of the collar is determined by the line (m, indicated by a dotted line in the figure) passing between two opposing points (n, n') on the maximum outer circumference of the collar and the cannula. The minimum angle (θ) formed with the longitudinal center line (l, indicated by a dotted line in the figure) of the inner hole, which is the flow path, is between 30° and 80°, preferably between 50° and
The angle is 75° and is provided on the outer periphery of the cannula insertion tip. Outside the above range, the compatibility and fixation of the brim with the heart wall or blood vessel wall will be poor, resulting in blood stagnation and thrombus formation as described above, which is contrary to the purpose of the present invention.

Since the shape of the heart is a collection of complex curved bodies, anatomically the above-mentioned range of 50° to 75° is preferable. The height of the bulge of the collar from the outer wall of the cannula is preferably in the range of 1 mm to 5 mm.
If it is less than 1 mm, the effects of the flange portion such as fixation and anti-thrombotic effects described above will be poor, and if it is more than 5 mm, the incision for insertion will become large and unnecessary invasion will be added to the myocardium and blood vessel wall, which is not preferable. It is. The position of the collar formed on the outer periphery of the insertion tip of the cannula is 50 degrees from the insertion tip as shown in Figure 4a.
It is preferable to have a diameter of up to 1 mm, but it may also be provided at the insertion tip as shown in FIG. 4b. The cannula shown in FIG. 4a is suitably used as a cannula for blood delivery to the aorta during heart surgery.

The shape of the brim depends on the purpose and the shape of the target heart.
Although it can be formed arbitrarily depending on the location, it may be formed as long as it can fit closely with the heart wall or blood vessel wall.

For example, as shown in FIG. 4a, the flange may be formed symmetrically around the outer periphery of the insertion tip of the cannula, with both sides of the flange substantially flat. The state in which this distal end is inserted into the aorta is shown in FIG. 5a, and as shown in the figure, the collar 2 provided on the outer periphery of the distal end of the cannula 1 closely fits the blood vessel wall 3 of the aorta.

Further, in consideration of blood flow, etc., it may be formed into an umbrella shape with a taper on the insertion surface side as shown in FIG. 5b. On the other hand, in the case of a child whose heart has a large curvature, the side surface on the insertion tip side can be made substantially flat, and the other side surface can be tapered, as shown in FIG. 5c. In any case, as shown in the figure, the heart wall and the collar are inserted and fixed in close contact with each other.

FIG. 6 shows an embodiment in which the cannula according to the present invention is used during heart surgery using an auxiliary artificial heart. The cannula 1A is used for aortic blood supply, and its insertion tip is inserted into the aorta 3A, and the other end is connected to the auxiliary artificial heart 4. The inserted state of the insertion tip in this case is shown in FIG. 6b. As shown in Fig. 4a, both sides of the flange portion are formed in a substantially flat shape, and the angle between the straight line passing through two points on the maximum outer circumference line and the longitudinal center line of the cannula inner hole is
It is set at 60°.

On the other hand, the cannula 1B is used for blood removal from the left heart, and its distal end is inserted into the left atrium, and the other end is connected to the auxiliary artificial heart 4. The aforementioned formation angle of the collar portion 2 in this cannula is 70°,
Both sides are formed almost flat.
According to this embodiment, the collar of the cannula is attached to the blood vessel wall 3.
A and the heart wall 3B were tightly fitted, and no thrombus occurred at the joint part even after one month of use.

As already explained, with the development of heart surgery,
(Auxiliary) Artificial hearts are being developed. However, the current situation is that there is currently no cannula suitable for this, and the cannula of the present invention makes this possible. A typical example of a device that meets this requirement is the cannula shown in FIG. 3, which has already been described.

In this case, the inner diameter of the cannula is preferably in the range of 3 mm to 15 mm in the case of a capillary tube. In other words, when using a cannula for heart surgery, if the inner diameter of the relatively thin part (tubule) of the part that bypasses the right heart from the insertion tip is smaller than 3 mm, the pressure drop will be too large and the cardiac function of the artificial heart (auxiliary) will be affected. This is because if the diameter is larger than 15 mm, it will put pressure on the patient's heart.

In addition, for relatively thick sections (thick tubes) from the part that exits the patient's body to the (auxiliary) artificial heart, the inner diameter must be 8 mm or more to minimize pressure loss, and if it is larger than 25 mm, In this case, a separate connector is required when connecting to the auxiliary artificial heart, which is undesirable because blood flow tends to stagnate at that part.

The wall thickness of the tube is also an important factor in the cannula according to the present invention. In other words, if the wall thickness of the tubule part is less than 0.2 mm, pulsating swelling is likely to occur due to rapid ejection from the heart, and furthermore, it is impossible to embed a reinforcing metal spiral. In this case, the cannula becomes thicker due to its thickness, which puts pressure on the heart, which is not desirable. Furthermore, since the thick tube portion is connected to an (auxiliary) artificial heart during use, it must be cut to an appropriate length, and therefore metal spiral reinforcement cannot be applied. Therefore, in order to prevent the kinking phenomenon (bending phenomenon), the wall thickness must be at least 1.2 mm. On the other hand, if it is 7 mm or more, it will be too thick and the workability will be poor. The ratio of the length of the thin tube to the length of the thick tube needs to be a certain length because the length of the cannula must be instantaneously adjusted according to the morphology of the patient's heart during surgery. On the other hand, if it is too long, it is unsuitable from the viewpoint of workability and cost, so it is optimal that the length of the thick tube section is in the range of 0.1 to 1 for the length of the thin tube section of 1.

In order to prevent deformation due to pulsation during use of this cannula, the above-mentioned wall thickness is provided, and at least a metal spiral is provided inside the part near the tip of the cannula, that is, the tubular part (tubule) with a small inner diameter. It is preferable that it be reinforced.

The most desirable material for the cannula is polyurethane or polyvinyl chloride containing a plasticizer. As the polyurethane, known polyester polyurethanes and polyether polyurethanes are widely used.

Molded products using these polyurethanes may be crosslinked to increase their mechanical strength.

Polyester-based polyurethanes are preferred as materials for the present invention because they are suitable for producing hard elastomers with high modulus of elasticity, high tear strength, and hardness.

The proportion of the crosslinking agent is preferably 0.01 to 5% by weight based on the total amount of polyurethane components.

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.

In this case, the amount of plasticizer mixed is preferably 40 to 100% by weight, and 50 to 100% by weight based on the polyvinyl chloride.
More preferably, it is 80% by weight.

The polyvinyl chloride may also contain suitable known stabilizers, such as non-toxic calcium-zinc organic complexes. The degree of polymerization of polyvinyl chloride is
It is preferable to use 500 to 2000.

In order to improve the antithrombotic properties of the cannula of the present invention, the inner surface that comes into contact with blood can be coated with a known antithrombotic material to improve blood compatibility.

As explained above, the cannula according to the present invention is suitably used in cardiac surgery, and by making the brim part specific, it is possible to easily and securely fix the insertion tip of the cannula during surgery, and to prevent blood clots. Furthermore, by forming the thin tube and thick tube integrally at a certain ratio with a specific inner diameter and wall thickness, and making the tube have a shape with a special curve,
(Auxiliary) It is also suitable for use in heart surgery using an artificial heart.

[Brief explanation of drawings]

FIG. 1 is a plan view of a conventionally used cannula, in which a is a cannula without a flange, b is a cannula with a flange, and c is a diagram of the cannula b inserted into the heart. FIG. 2 is a perspective view of the cannula according to the present invention, and FIG. 3 is a perspective view of another embodiment of the cannula according to the present invention, which is suitable for use with an (auxiliary) artificial heart. . FIG. 4 is a perspective view showing the formation position and condition of the collar, and FIG. 5 is a sectional view showing the state of close contact between the collar and the heart wall. FIG. 6a is a perspective view showing the state in which the cannula according to the present invention is used in heart surgery, and FIG. 6b is a partial sectional view showing the state in which the insertion tip is inserted. In the symbols, 1 indicates a cannula, 2 indicates a collar, and 3 indicates a heart wall or a blood vessel wall.

Claims (1)

[Claims] 1. In a cannula having a flange bulging on the outer periphery of the insertion tip, a straight line passing between two opposing points on the maximum outer periphery of the flange is the center line in the length direction of the inner hole of the cannula, which is the flow path. The cannula is characterized in that the flange is inclined and provided on the outer periphery of the insertion tip with a minimum angle of 30° to 80°.