JPH0239463Y2 - - 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 an artificial 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, namely, 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. As a new treatment (support) to help save the lives of patients with chronic congestive heart disease and acute myocardial infarction who are severely ill and cannot be saved using conventional surgical methods.
Development of an artificial heart is progressing. (Auxiliary) artificial hearts have not yet been brought to market, and only a few clinical cases have been seen so far at several research institutes that are conducting research and development of artificial hearts worldwide. Various types of (auxiliary) artificial hearts are being developed, but which type (auxiliary)
Even with an artificial heart, in order for heart surgery to be successful, the patient's own heart must be assisted until it functions normally, and in order to play the role of saving the patient's life, a special cannula for the (auxiliary) artificial heart that does not previously exist is required. must be developed. For example, even if a cannula conventionally used in a heart-lung machine is used for an (auxiliary) artificial heart, this cannula has a small inner diameter and therefore suffers from a large pressure drop, making it impossible to fully utilize the functions of the (auxiliary) artificial heart. The problem is that there is no. In order to fully demonstrate the function of the (auxiliary) artificial heart, the first requirement is that the inner diameter of the cannula on the side where it connects to the (auxiliary) artificial heart must be larger than a certain level. If this part does not have an inner diameter larger than a certain size, (auxiliary)
This is undesirable since the blood pumped from the artificial heart suffers a pressure drop before reaching the aorta or pulmonary artery, drastically reducing the function of the (auxiliary) artificial heart.

The next requirement is that the cannula do not compress the patient's heart. The opposite problem occurs if the cannula is too thick over its entire length. That is, the patient's heart is located within a wall plate of a certain size, and the heart beats vigorously within this wall. If the cannula is too thick over its entire length, the cannula will compress the heart, restricting the movement of the heart, and conversely reducing the cardiac assist function. That is, the tip of the cannula is inserted into the atrium of the heart under treatment through an open chest incision, with the tubule portion bypassing the right heart, as shown in FIG. Therefore, the thinner the tip, the easier it is to insert, and since the thin tube part is placed in contact with the heart as described above, the heart will not be compressed every time the blood pump beats or when operating the cannula. Therefore, the thinner the material, the better. Therefore, the cannula for the (auxiliary) artificial heart must be kept below a certain thickness at least in the portion that comes into contact with the patient's heart. This conflicts with the above-mentioned requirement to make the cannula thicker, so the ideal cannula would be thicker near the joint of the (auxiliary) artificial heart, and would make contact with the patient's heart up to the tip of the cannula. It is necessary that certain portions be relatively thin. Also, the cannula does not pulsate due to the influence of the heartbeat. The pressure of pumping from the heart is
It can reach up to 200 mmHg, and this pressure is 60 to 120 per minute.
It is a violent pulsation. Pulsating swelling of the cannula must not occur in response to this rapid ejection of pressure. If the cannula deforms as blood is ejected from the (auxiliary) artificial heart, that 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 pulsation of blood flow during surgical use. Furthermore, as already mentioned, the patient's heart is located on a narrow sidewall and is beating vigorously. There are two types of cannula; one is the blood removal cannula, which is used for the right atrium, left atrium,
Alternatively, it is a cannula that drains blood from the pulmonary vein or vena cava and guides it into the (auxiliary) artificial heart.The other is a blood feeding 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 reason, it is preferable that the cannula be bent and shaped so that it can be adapted to these requirements.
Furthermore, the curved portion of the cannula must be free from pulsation and kinking (kinking) caused by blood pulsations.

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, and in particular, the hearts of people with heart disease exhibit abnormal enlargement, commonly referred to as cardiac hypertrophy, and its appearance differs from person to person. No canyule has ever existed that is widely applicable to these variously shaped hearts. However, in order to actually use an (auxiliary) artificial heart, these requirements must be met.

Note that it is necessary to be able to instantly adjust the length of the cannula during surgery. This is because, as already mentioned, the shapes of patients' hearts vary widely, so when using an auxiliary artificial heart, it is necessary to be able to adjust its length.

The present invention was developed in response to the above demands, and is suitable as a cannula for (auxiliary) artificial hearts. The cannula is integrally constructed with a thick tube with a relatively large inner diameter, with the inner surface communicating seamlessly, and the inner diameter (diameter) of the thin part leading to the insertion tip of this cannula is 3 to 15 mm.
mm, and the thickness is between 0.2 and 5 mm, and the relatively large inner diameter part has an inner diameter (diameter) of 8 to 25 mm, and a thickness of 1.2 to 7 mm, and the length A of the thin tube and the thick tube are The cannula is characterized in that the ratio B/A of length B is 1 to /10.

As explained above, it is essential that the inner diameter of the cannula falls within the above range. That is,
If the inner diameter of the relatively thin part (tubule) from the insertion tip of the cannula that bypasses the right heart is smaller than 3 mm, the pressure drop will be too large and the cardiac function of the ventricular assist device will deteriorate; if it is larger than 15 mm, the patient's This is because it puts pressure on the heart and defeats the purpose of the present invention.

The blood pump that makes up the auxiliary artificial heart pumps at 2 to 30% per minute.
A cannula with a capacity of 8㎜ has been developed, and the cannula has one end connected to a blood pump and the other end inserted into the heart, as shown in Figures 4 and 5.
If the inner diameter of the cannula is less than the aforementioned 3 mm, the blood in the blood removal cannula will not flow into the blood pump in an amount commensurate with its capacity, resulting in a large pressure drop, which will reduce the cardiac function of the blood pump and, by extension, the auxiliary artificial heart. In addition, in the case of a blood feeding cannula, the required amount of blood is not delivered into the heart, resulting in a decrease in the cardiac function of the auxiliary artificial heart. On the other hand, in clinical cases, if the diameter is larger than 15 mm, the heart will be compressed.

In addition, in the relatively thick part (thick pipe) from the part that exits the patient's body to the auxiliary artificial heart, artificial valves as check valves are installed in the blood inlet pipe and blood discharge pipe of the blood pump. The diameters of both tubes are determined by the diameter of this valve and the capacity of the blood pump. Based on these conditions, the inner diameter must be 8 mm or more, and if it is larger than 25 mm, a separate connector will be required when connecting to the auxiliary artificial heart, which may cause blood flow to stagnate in that area. Undesirable.

The wall thickness of the tube is also an important factor in the canyule 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 cannot be reinforced with a metal spiral. Therefore, in order to prevent the kinking 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 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.

All known shapes can be used for the insertion tip of the cannula of the present invention. Further, in order to stabilize insertion, the insertion portion may be provided with a ring-shaped bulge as shown in FIGS. 1 to 3.

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

The present invention will be further explained below based on the drawings.

Figure 1 shows the first embodiment of the present invention, in which the thin tube leading to the insertion tip is reinforced with spiral metal except for a part of the tip, and the thick tube is reinforced with spiral metal. The inner diameter of the tube section is 16 mm and the wall thickness is 3 mm, the inner diameter of the thin tube section is 9 mm and the wall thickness is 2 mm, and the ratio of the length of the thick tube section to the length of the thin tube section is 1:1. When the cannula of this example was used as the blood feeding cannula 6 shown in FIG. 4 for cardiac surgery using an auxiliary artificial heart, it could be used without any problems.

FIG. 2 shows a second embodiment of the present invention. The inner diameter of the thin tube part of the cannula in this example is 11
mm, the wall thickness is 1 mm, the inner diameter of the thick tube section is 14 mm, the wall thickness is 2 mm, and the ratio of the length of the narrow tube section to the length of the thick tube section is 1:0.5. The spiral is reinforced from a part of the thick part of the cannula to the insertion part at the tip of the cannula.
In addition, the tip of the canyule is bent.
When the cannula of this example was used as the blood removal cannula 7 shown in FIG. 4, it could be used without any particular problem.

FIG. 3 shows a third embodiment of the present invention.

In the cannula of this example, the length of the thin tube section, which is about half of the length leading to the insertion tip, has an inner diameter of 12 mm and a thickness of 2 mm, while the inner diameter of the thick tube section gradually tapers from 15 mm to 13 mm, and the wall thickness is 2 mm. This is an example in which the cannula is bent at three points (point A, point B, and point C) in different directions.

FIG. 4 shows a state of left heart assist in which the auxiliary artificial heart 5 is used, the cannula 7 of Example 2 is used for blood removal, and the cannula 6 of Example 1 is used for blood transfer. This is an example in which blood is supplied from the left atrial appendage 7 and sent to the ascending aorta. As mentioned above, it could be used without any problems.

FIG. 5 is an example of left heart assist in which the cannula 1 of Example 3 is used for blood removal and the cannula 6 of Example 1 is used for blood transmission.

In this example, blood is removed from the border between the pulmonary vein and the right atrium 3 on the back side of the heart 2 and inserted into the left atrium 4, and blood is sent to the ascending aorta. In this example, a pneumatic pump type pump 5 was used as the auxiliary artificial heart. In this example, it could be used very suitably.

[Brief explanation of the drawing]

FIGS. 1, 2, and 3 are perspective views showing embodiments of the cannula according to the present invention, and FIGS. 4 and 5 show a pneumatic sac-type pump as an auxiliary artificial heart according to the present invention. FIG. 3 is a state diagram showing one embodiment of connecting to the heart using such a cannula.

Claims (1)

[Claims for Utility Model Registration] 1. A capillary tube communicating with the insertion tip and a thick tube whose inner surface is seamlessly connected to the capillary tube and whose inner diameter is larger than the capillary tube, the inner diameter of the capillary tube being larger than that of the capillary tube. is 3mm~
15 mm and a thickness of 0.2 to 5 mm, and the inner diameter of the thick tube is 8 mm to 25 mm and a thickness of 1.2 mm to 7 mm.
A cannula characterized in that the ratio B/A of the length A of the thin tube and the length B of the thick tube is 1 to 1/10. 2. The cannula according to claim 1, wherein the thin tube and/or the thick tube, excluding the insertion tip, are reinforced with a metallic spiral.