JPH035820B2 - - 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 for use in cardiac surgery. Conventionally, a cannula for a heart-lung machine has been used during heart surgery.

The present invention provides a new cannula developed for a completely new type of heart surgery different from conventional heart surgery techniques, that is, an artificial heart or an auxiliary artificial heart (hereinafter referred to as an auxiliary artificial heart).

Although the average lifespan of humans is increasing year by year with advances in medicine, the proportion of causes of death from heart disease is increasing year by year. Among patients with heart disease, the (auxiliary) artificial heart is a new treatment that can save the lives of patients with chronic congestive heart disease, acute myocardial infarction, and post-surgical low stroke volume syndrome that are difficult to survive with conventional surgical methods. development is underway. However, (auxiliary) artificial hearts have not yet been put on the market, and only a few clinical cases have been seen so far at several research institutions that are conducting research and development of (auxiliary) artificial hearts worldwide. do not have. Various types of (auxiliary) artificial hearts are being developed, but regardless of the type of (auxiliary) artificial heart, it is important to ensure that the (auxiliary) artificial heart has sufficient cardiac function.
During this time, in order to successfully perform cardiac surgery on critically ill patients, we need to support the patient's own heart until it functions normally, and in order to play the role of saving the patient's life, we need special equipment for the artificial heart that does not previously exist (auxiliary). A canyule must be developed. For example, if a cannula conventionally used in a heart-lung machine is used for an (auxiliary) artificial heart, this cannula has a small inner diameter, resulting in a large pressure drop, and the shape of the cannula does not correspond to the shape of the heart. There is a problem in that the heart cannot function to its full potential. (Auxiliary) In order to fully demonstrate the function of an artificial heart, the first thing required is the shape of the cannula. The patient's heart is located in the narrow space between the pleural cavities and is beating rapidly. There are two types of cannula; one is to remove blood from the right atrium, left atrium, pulmonary vein, or vena cava (auxiliary);
It is a blood removal cannula that leads into the artificial heart.
The other is a blood cannula that connects the (auxiliary) artificial heart to the pulmonary artery or aorta. All of these cannulae need to be short in order to bypass the patient's constantly active heart without restricting the movement of the patient's heart, and to reduce pressure drop as much as possible. For this purpose, the canyule bends in a special way,
It is required to have a special shape. Moreover, it is necessary that the curved portion of the cannula does not cause pulsation or kinking phenomenon (kinking phenomenon) due to blood pulsation.

In addition, the shape of the cannula must be widely applicable. This is because there are a wide variety of patients, including adults, children, men, and women. In particular, the hearts of people with heart disease exhibit an abnormal enlargement commonly referred to as cardiac hypertrophy, and its appearance differs from person to person. Until now, there has never been a cannula that is widely applied to these various forms of abnormal hearts. However, in order to actually use an (auxiliary) artificial heart, it must meet these requirements. Furthermore, the pressure of ejection from the heart reaches 200 mmHg, and this pressure is a violent pulsation of 60 to 120 times per minute, and the pulsating swelling of the cannula occurs in response to this rapid ejection of pressure. It is necessary that this should not occur. If the cannula deforms as blood is ejected from the (auxiliary) artificial heart, the deformation will absorb the pulsating flow of blood, greatly impeding the function of the (auxiliary) artificial heart. I end up losing money.

Therefore, it is necessary that the entire cannula is free from pulsating deformation due to the pulsation of blood flow in the cannula during surgical use. Furthermore, if the cannula is too thick over its entire length, the cannula used for treatment will press the heart and restrict the movement of the heart, reducing the cardiac assist function. Therefore, it is preferable that the cannula for an (auxiliary) artificial heart be kept within a certain thickness at least in the portion that contacts the patient's heart. In addition, it is preferable that the inner diameter on the side of the joint with the (auxiliary) artificial heart is also larger than a certain value. If this part does not have an inner diameter above a certain level, it is preferable that the blood pumped from the (auxiliary) artificial heart cause a pressure drop before reaching the aorta blood vessel or pulmonary artery blood vessel, drastically reducing the function of the (auxiliary) artificial heart. do not have. Additionally, it is required that the length of the cannula can be adjusted instantaneously during surgery. This is because, as already mentioned, the shapes of patients' hearts vary widely, and when using an (auxiliary) artificial heart, the cannula must be adjustable in length.

By providing a cannula that satisfies the required performance as described above, the auxiliary artificial heart can fully demonstrate its functions.

The present invention has been newly developed in response to the above-mentioned needs, and is excellent as a cannula for an (auxiliary) artificial heart, especially for blood removal.
The blood removal cannula removes blood from the patient's left atrium and leads it to the (auxiliary) artificial heart, and the pulsating blood pumped from this (auxiliary) artificial heart is sent to the ascending aorta. The above-described surgery is considered to be most commonly used when using an artificial heart to assist cardiac function. In other words, although many researchers are developing many surgical methods using (assistant) artificial hearts, in actual cases, the majority of surgeries involve assisting the patient's left heart. It seems that it occupies a large part. In this case, from the patient's heart (auxiliary)
Blood is introduced into the artificial heart by removing blood from the patient's left atrium and leading to the (auxiliary) artificial heart. There are various methods for this, but the method most desired by cardiac surgeons is as shown in Fig.
is inserted into the left atrium 4 to remove blood from the left atrium. In this case, the cannula needs to be shaped so as to detour along the patient's heart 2 to the front side of the heart, as short as possible, and not to obstruct the movement of the patient's heart.

The present invention is a special cannula newly developed in response to such demands, in which the tip part connected to the insertion tip of the cannula is bent into an arc shape with a radius of curvature of 10 to 90R. Curvature at a bending point that has at least one bending point (referred to as the first, second, third, ... bending point from the one furthest from the tip of the cannula) and is adjacent to the arc-shaped portion of the tip. The radius is smaller than the radius of curvature of the tip. Until now, there has never been a canyule with such a complicated curved shape. In order for the (auxiliary) artificial heart mentioned above to perform this function, it must be inserted into the desired position in the left atrium as short as possible without interfering with the movement of the patient's heart. A canyule is required.

The cannula of the present invention does not necessarily need to be bent in the same plane; in other words, the cannula may be bent three-dimensionally in different directions. First, the radius of curvature of the tip of the cannula from the insertion tip to the next bending point is
10 to 90R, and is characterized in that the radius of curvature at the first bending point following this is smaller than the radius of curvature of the tip. What is important about the cannula of the present invention is how the distal end of the cannula curves around the right atrium and how it curves at the bending point set along the right ventricle. In order to be placed in the space between the pleural cavities along the right atrium, the tip must have a radius of curvature of 10 to 90R.

Here, nR refers to the radius of a circle of curvature with a radius of nmmm.
If the curvature is smaller than 10R, the curvature is too large and puts pressure on the heart, and if it is larger than 90R, abnormal force is applied to the tip of the cannula, which may dislodge the tip inserted into the left atrium or put pressure on the lungs, which is undesirable. .
The cannula, which has bypassed the right atrium, must now be brought forward along the right ventricle and along the bulge in front of the heart, and must be bent with a considerably large curvature. Generally, in this case, in order to follow the right ventricle below the right atrial appendage of the heart, the radius of curvature is preferably 5 to 30R, and must necessarily be smaller than the radius of curvature of the tip. Further, when there are two bending points, the radius of curvature at the first bending point may be equal to or larger than the radius of curvature at the second bending point, but it is preferably smaller than the radius of curvature at the tip of the cannula. If the radius of curvature is smaller than 5R, the bend is too steep and the blood does not flow smoothly at that point, creating a vortex, resulting in hemolysis, coagulation, and other undesirable phenomena. Moreover, if it is larger than 30R, the cannula detours too much and the length of the cannula becomes unduly long, causing a pressure drop in the blood flow, which is not preferable. That is, the present inventors have confirmed that the most preferable range of the curvature of the first and second bending points is 5 to 30R by adapting it to various actual hearts.

When the present invention has two bending points, the distance between the first bending point and the second bending point is in the range of 30 mm to 80 mm, the first bending angle and the second bending angle are each 90° to 170°,
Preferably it is in the range of 100° to 160°. Here, the bending angle refers to the angle formed by the longitudinal centerline of the cannula before and after each bending point. Whether this angle of curvature is less than 90° or greater than 170°, it is not possible to position the cannula along the outer wall of the patient's heart and into the narrow interpleural space. If you try to forcefully place it, there is a risk that it will put excessive pressure on or strain the patient's heart, causing a delay in recovery of the patient's heart function.

Also, the length of the cannula from the tip of the cannula to the first bending point of the cannula must be 80 to 250 mm. If this length is shorter than 80 mm, it will put pressure on the patient's heart and slow down the patient's heart recovery.
If it is larger than 250 mm, there is a risk that it will put pressure on the lungs or that the tip of the cannula may come off due to the tension of the cannula.

In the present invention, the material constituting the cannula is most preferably 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.

Known polyvinyl chloride plasticizers such as dioctyl phthalate and dioctyl adipate are widely used as plasticizers for polyvinyl chloride. It may also be formed from paste.

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. It is preferable to use polyvinyl chloride having a degree of polymerization of 500 to 2000.

In order to improve 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.

Further, the cannula of the present invention is preferably reinforced with a metal spiral in order to prevent deformation due to pulsation during use and kinking phenomenon (bending phenomenon).

In order for the blood pump, which assists or completely replaces the heart's function, to fully demonstrate its function as an auxiliary heart or a complete heart, the cannula must be placed at the tip of the cannula so as not to compress the heart and hinder its movement.
The part that bypasses the heart should not be too thick.
A suitable diameter of the tube is 3 to 15 mm, while the portion remote from the patient's heart (outside the body) is preferably thick to avoid pressure loss.

The preferred tube diameter is 8 to 25 mm. Length ratio A/B of the thick part (A part) and the thin part (B part) of the pipe diameter
is preferably 1/1 to 1/10. As shown in FIGS. 1 to 3 as an embodiment, the cannula of the present invention has a relatively thin three-dimensionally bent tube leading to the tip of the cannula, and a relatively thick (auxiliary) tube connected to the artificial heart. The inner surface is seamlessly molded into one piece.

FIG. 1 shows a first embodiment of the invention. In this example, the distal end connected to the insertion tip has a circular arc shape of 30R, and the radius of curvature at the second bending point following this is 10R, the bending angle is 127°, the first bending angle is 113°,
An example is shown in which the radius of curvature at this point is 7R.

The material constituting the cannula is polyvinyl chloride containing a plasticizer, and 70% by weight of dioctyl phthalate is used as the plasticizer based on the polyvinyl chloride. The inner diameter of the relatively thin three-dimensionally bent tube section is 11 mm, and the insertion section of the cannula is provided with an annular collar to facilitate fixation of the insertion section. In order to maintain the shape stability and prevent the kinking phenomenon, a metallic spiral is placed inside the cannula, surrounding the curved tube, from a distance of approximately 2 cm from the collar at the tip of the cannula. The thickness of the tube from the cannula tip to the part protected by this metal spiral is
The length of the tube is 1.1 mm, and the part without the spiral to the other end is 2.1 mm, and the content of the tube in this part is 14 mm.

FIG. 2 shows a mode in which this example is used for left ventricular assistance using a sack-type auxiliary artificial heart.

The tip of the cannula in this example bypasses the right atrium, so it is bent into a semicircular shape, and the contact point P ₂ between the right atrium and right ventricle serves as the second bending point. The radius of curvature of the tip that bypasses the right atrium is 30R, the radius of curvature at the second bending point (point P ₂ ) is 10R, and the bending angle is
127°, the first bending angle is 113°, and the radius of curvature at the first bending point is 7R.

Also, the distance from the tip of the cannula to the first bending point is
The length of the cannula from the first bending point (P 1 ) to the auxiliary heart is 170mm, and the length of the cannula from the first bending point (P ₁ ) to the tip of the cannula is reinforced by a metal spiral. The wall thickness of this part is 1.1mm, and the inner diameter is 11mm, while the thickness of the part from the first bending point to the auxiliary heart is
2.1mm inner diameter is 14mm. As shown in the figure, it could be used suitably without any problems.

Another embodiment is shown in FIG. In this figure, the metal spiral is reinforced up to the collar at the tip of the cannula. Figure a is a view seen from the side, figure b is a view seen from the front, and figure c is a view seen from the plane.

In this figure, the arc-shaped part that connects to the tip of the cannula is 42R, and the radius of curvature of the second bending point _P2 is
11R, the bending angle is 110°, the radius of curvature of the first bending point P ₁ is
15R, the bending angle is 126°. This example is made of polyvinyl chloride containing 80% by weight of dioctyl phthalate, and the length of the thin part of the cannula is 158 mm, the inner diameter is 12 mm, and the thickness is 0.9 mm.
mm, the length of the thick part is 70mm, the inner diameter is 15mm, the thickness is
It is 2.2mm. As shown in FIG. 2, this example could be used suitably without any problems.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the cannula according to the present invention, FIG. 2 is a diagram showing the cannula according to the present invention used together with an auxiliary artificial heart during heart surgery, and FIG. These are overall perspective views seen from three directions: Figure A is a side view, Figure B is a top view, and Figure C is a view from the front.

Claims (1)

[Claims] 1. A cannula used in connection with an (auxiliary) artificial heart used to partially or completely compensate for decreased cardiac function, the tip of which connects to the tip inserted into the heart is 10R or more. It is bent into an arc shape with a radius of curvature of 90R, and has at least one bending point following the tip, and the radius of curvature at the bending point adjacent to the tip is between 5R and 30R, and the tip has at least one bending point adjacent to the tip. A cannula for an (auxiliary) artificial heart, characterized in that it is configured with a radius of curvature smaller than the radius of curvature of the cannula. 2. The cannula according to claim 1, which is bent with at least two bending points following the tip, and has a three-dimensional shape with different directions.