Antegrade blood infusion cannula

Abstract

The present invention provides a cannula that allows safe and effective antegrade blood transfer from the ascending aorta while achieving a reduced diameter. The cannula comprises an antegrade blood return tube (1) and a blood transfer tube (4). A guidewire hole extending in the longitudinal direction is provided at approximately the axial center of the distal end of the antegrade blood return tube (1), and a guidewire tube (5) is disposed in the hole. A guidewire (50) is inserted into the guidewire tube (5). The antegrade blood return tube (1) is integrally molded and comprises a distal tapered portion provided at the distal end and a trunk portion provided at the proximal end. The distal tapered portion is composed of a distal portion and fins, and the trunk portion is composed of fins and a cylindrical portion. The proximal end of the distal portion, the fins, and the distal end of the cylindrical portion form a louver (2). The louver (2) is supported by a total of four beams provided in the longitudinal direction of the antegrade blood return tube (1), from the distal portion to the cylindrical portion.

Description

[Technical Field]

[0001] The present invention relates to a cannula for use in an extracorporeal circulatory assist device. [Background technology]

[0002] When a patient experiences a myocardial infarction or other condition that causes a sudden decline in the heart's pumping function, the left ventricle's volume increases excessively, causing the left ventricle to fail to contract. Under such circumstances, the left ventricle is unable to pump enough blood, and an insufficient supply of oxygenated blood to vital organs throughout the body, including the brain, becomes necessary. In such cases, intervention with an extracorporeal circulatory assist device is necessary.

[0003] Currently used percutaneous extracorporeal circulatory assist devices include the intracardiac pump catheter for circulatory support (IMPELLA (registered trademark)) and percutaneous cardiopulmonary support (ECMO (PCPS)). Although IMPELLA can reduce cardiac load, it has problems with not being able to oxygenate the patient and being subject to strict facility standards. In contrast, ECMO is widely used because it allows oxygenation and has no facility restrictions, but it has major problems such as increased cardiac load due to retrograde blood flow, and vascular complications associated with the need for large-diameter cannula placement.

[0004] First, regarding the issue of increased cardiac load due to retrograde blood flow, ECMO is a device that supplies oxygenated blood to vital organs, particularly the brain, but because blood is sent at a high flow rate in the opposite direction to the blood sent from the heart, it places a strain on the heart, which may delay the recovery of cardiac function. Regarding the second issue of vascular complications associated with large-diameter cannulae, the incidence of lower limb ischemia after insertion of an ECMO cannula from the femoral artery is said to be around 10-70%. If lower limb ischemia occurs, it can lead to compartment syndrome or lower limb necrosis, and patients with lower limb ischemia have a significantly worse prognosis. According to a meta-analysis of 1,763 adult patients focusing on the outcomes and complications of ECMO, nearly 50% of patients receiving ECMO survive until discharge, even in conditions where death is usually likely, while a significant number of patients (45%) die from complications such as bleeding (33%) and sepsis (22%) associated with long-term ECMO placement (see, for example, Non-Patent Document 1).

[0005] In recent years, a method called "ECPELLA" has been developed that combines Impella with ECMO, which allows oxygenated blood to be supplied to the brain while reducing cardiac load. However, since this method still uses Impella, there is a problem in that strict facility standards must be met.

[0006] Therefore, a cannula capable of antegrade blood transfer is known as a blood transfer cannula used in extracorporeal circulation of blood using a heart-lung machine (see Patent Document 1). This cannula consists of an outer tube and an inner tube, and blood passes through an annular return flow path formed between the inner tube and the outer tube, whose tip is closed, and is released in the antegrade direction from the blood release hole in the outer tube into the aorta. However, the cannula of Patent Document 1 has an inward-facing protruding edge on the hole edge of each blood discharge hole as a mechanism for guiding the blood discharge direction in the antegrade direction. However, the inward-facing protruding edge is only formed on the hole edge near the base end of the tube, and no mechanism for guiding the blood discharge direction in the antegrade direction is provided on the hole edge near the tip of the tube, resulting in a problem of insufficient antegrade guidance. Furthermore, when the tube is removed, the hole edge near the tip of the tube abuts against the inner wall of the blood vessel, causing damage to the inner wall. Furthermore, the cannula of Patent Document 1 has the problem that, because the outer tube is arranged to cover the inner tube, it is difficult to reduce the diameter of the cannula due to its structure, and it lacks a mechanism for inserting a guidewire, resulting in reduced convenience. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-23970 [Non-patent literature]

[0008] [Non-Patent Document 1] Alberto Zangrillo et al., "A meta-analysis of complications and mortality of extracorporeal membrane oxygenation", Crit Care Resusc. 2013 Sep;15(3):172-8. Summary of the Invention [Problem to be solved by the invention]

[0009] In view of the above circumstances, an object of the present invention is to provide a cannula that can safely and effectively send blood antegrade from the ascending aorta while achieving a reduced diameter. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention for extracorporeal membrane oxygenators Antegrade blood infusion cannula (Hereinafter referred to as antegrade blood infusion cannula) is a cannula whose tip is placed in the ascending aorta and sends blood supplied from an extracorporeal membrane oxygenator in an antegrade direction from the ascending aorta, the cannula including a blood sending tube provided on the base end side of the cannula and connectable to the extracorporeal membrane oxygenator, and a distal tapered portion formed on the tip side of the cannula, the diameter of which decreases toward the tip, and at least one of an antegrade blood return path that reverses blood from retrograde to antegrade and directs it toward the base end, or a lateral blood return path that directs blood from retrograde to lateral, is provided at the distal tapered portion. to A non-retrograde blood return tube is provided. The provision of a non-retrograde blood return tube prevents blood supplied from the extracorporeal membrane oxygenator from colliding with blood from the heart, thereby effectively reducing cardiac load. A non-retrograde blood return tube is a tube provided with at least either an antegrade blood return path or a lateral blood return path, and a blood return tube provided with an antegrade blood return path in at least a portion of the tube is also referred to as an antegrade blood return tube in this specification.

[0011] The tapered distal end facilitates insertion of the antegrade blood infusion cannula into a blood vessel. The cannula of Patent Document 1 also has a tapered distal end, but lacks a blood release hole. Therefore, when attempting to inject blood in the antegrade direction from a deeper position in the ascending aorta, the cannula must be inserted close to the coronary artery, potentially interfering with the coronary artery or the inner wall of the blood vessel. In contrast, the antegrade blood infusion cannula of the present invention has an antegrade blood return path in the tapered distal end. Therefore, when the distal end is positioned in the ascending aorta, blood can be infused in the antegrade direction from a deeper position without interfering with the coronary artery, thereby reducing the strain on the patient's body. Furthermore, a lateral blood return path may be provided to redirect blood from a retrograde direction to a lateral direction, taking into account blood infusion into the coronary artery. A lateral blood return path is a blood return path perpendicular to the longitudinal axis. The extracorporeal membrane oxygenator here refers to a device that oxygenates drawn blood outside the body and then sends it back into the body, such as a percutaneous cardiopulmonary support system (ECMO).

[0012] In the antegrade blood transfer cannula of the present invention, it is preferable that an antegrade blood return path, which reverses the blood flow from retrograde to antegrade and directs it toward the proximal end, is further provided in the trunk of the non-retrograde blood return tube. By providing an antegrade blood return path in the trunk, the antegrade nature of blood transfer can be further improved.

[0013] In the antegrade blood transfer cannula of the present invention, the non-retrograde blood return tube preferably has a closed distal end, a hollow truncated cone, and a plurality of fins, each with a circular top and bottom opening, that increase in diameter from the distal end to the proximal end of the cannula, while the bottom opening has a constant or increasing diameter. The fins are preferably spaced apart along the longitudinal direction of the cannula, and a beam is provided to hold the fins. The gaps formed by the fins and beams function as an antegrade or lateral blood return path. By providing multiple fins of this shape at intervals, the gaps formed by the fins and beams function as a blood return path. In the antegrade blood return path, the gaps allow the transferred blood to be effectively reversed in the antegrade direction. In the lateral blood return path, the blood can be ejected perpendicular to the longitudinal axis of the cannula. Furthermore, the louvered fins allow for increased blood transfer volume and also allow the cannula to be flexible and have a smaller diameter. By making the cannula flexible, the fin portion can be contracted in diameter by external force when the cannula is inserted, thereby reducing the resistance to insertion into the body.

[0014] Here, when the gap formed by the fins and the beams functions as an antegrade blood return path, the angle between the antegrade blood return path and the axial direction of the cannula is preferably 20 to 40°. If this angle is less than 25°, the axial length of the beams holding the fins increases, and buckling easily occurs at the tapered tip due to resistance to insertion of the cannula into the blood vessel. Furthermore, if the angle exceeds 40°, the length of the antegrade blood return path formed between the fins becomes short, and the ability to guide blood in the antegrade direction decreases. On the other hand, when the gap formed by the fin and the beam functions as a lateral blood return path, the angle between the lateral blood return path and the axial direction of the cannula is preferably approximately 90°. By setting the angle at approximately 90°, blood can be ejected perpendicular to the long axis of the cannula, and blood can be sent to the coronary artery without retrograde blood return. Note that the distal end being closed means that the blood flow path is closed, and the distal end of the guidewire tube, which will be described later, is open.

[0015] In the antegrade blood infusion cannula of the present invention, it is preferable that at least the outer surfaces of the fins are held by the beams, which effectively prevents the outer edges of the outer surfaces of the fins from catching on the inner wall of the blood vessel and damaging the inner wall of the blood vessel.

[0016] In the antegrade blood infusion cannula of the present invention, the outer edges of the outer surfaces of the fins are preferably formed in a reverse tapered shape, which effectively prevents the outer edges of the outer surfaces of the fins from catching on the inner wall of the blood vessel and damaging the inner wall of the blood vessel while maintaining antegrade blood infusion through the fins.

[0017] In the antegrade blood transfer cannula of the present invention, the beams are preferably spaced at regular intervals around the circumference of the non-retrograde blood return tube. This prevents buckling during use of the antegrade blood transfer cannula. For example, if there are four beams, they are spaced at 90° intervals, and if there are three beams, they are spaced at 120° intervals. There is no limit to the number of beams, but if more beams are provided, it is preferable to make each beam thinner in order to ensure a blood return path between the fins.

[0018] In the antegrade blood transfer cannula of the present invention, the angle formed by the outer edge of the outer surface of the fin with the axial direction of the cannula is preferably 10 to 30°. If the angle is less than 10°, the corners of the outer edge of the outer surface of the fin will not face inward sufficiently, making it easier for biological tissue to enter the depressions formed by the fin structure, and as a result, the inner wall of the blood vessel will be easily damaged when the cannula is removed from the body using the outer edge of the outer surface. Furthermore, if the angle exceeds 30°, the length of the blood return path formed between the fins will be shortened, reducing the ability to guide blood in the antegrade direction. Therefore, by setting the angle to 10 to 30°, both antegrade blood flow and safety can be achieved.

[0019] The antegrade blood infusion cannula of the present invention may further include a guidewire tube, which is provided approximately in the center of the cannula's axis and through which a guidewire is inserted from the proximal end to the distal end. By providing the guidewire tube, the antegrade blood infusion cannula can be made thinner while allowing a guidewire to be inserted inside, improving convenience. Furthermore, by providing the guidewire tube approximately in the center of the cannula's axis, the guidewire tube is less likely to interfere with the blood return path. [Effects of the Invention]

[0020] The antegrade blood infusion cannula of the present invention has the advantage of being able to reduce the diameter and reduce the cardiac load on the patient. This reduces the incidence of vascular complications associated with the placement of a large-diameter cannula. The antegrade blood infusion cannula of the present invention also has the advantage of being able to infuse oxygenated blood antegrade from the ascending aorta, effectively delivering blood to the entire body, including the brain. Furthermore, it has the advantage of being able to prevent damage to the inner walls of blood vessels when inserting or removing the cannula. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is an external view of an antegrade blood infusion cannula according to a first embodiment. [Figure 2] FIG. 1 is a perspective view of an antegrade blood return tube according to a first embodiment; [Figure 3] FIG. 1 is a right side view of the antegrade blood return tube of the first embodiment. [Figure 4] 1A and 1B are front and rear views of a first embodiment of an antegrade blood return tube; [Figure 5] Louver illustration [Figure 6] 1 is a cross-sectional image of the antegrade blood return tube of the first embodiment. [Figure 7] Explanatory diagram of the beam [Figure 8] 1 is a diagram illustrating the use of the antegrade blood infusion cannula of the first embodiment. [Figure 9] FIG. 1 is a functional diagram of the antegrade blood infusion cannula of the first embodiment. [Figure 10]FIG. 10 is a right side view of the antegrade blood return tube of the second embodiment. [Figure 11] Image of the antegrade blood infusion cannula of the present invention in use [Figure 12] Image of conventional blood transfer cannula in use [Figure 13] Cross-sectional image of the antegrade blood return tube of the third embodiment [Figure 14] Cross-sectional image of the antegrade blood return tube of the fourth embodiment DETAILED DESCRIPTION OF THE INVENTION

[0022] First, an image of how a conventional blood transfer cannula is used will be described. Figure 12 shows an image of how a conventional blood transfer cannula is used. In conventional retrograde blood transfer, blood 9b that has been sufficiently oxygenated in an extracorporeal membrane oxygenator (not shown) is sent through the descending aorta 91, aortic arch 92, right subclavian artery 94, right common carotid artery 95, left common carotid artery 96, and left subclavian artery 97, and is then supplied to the brain 82. However, in the case of conventional retrograde blood transfer, blood 9b collides with blood 9c pumped out from heart 81 at the position of ascending aorta 93, causing cardiac strain. In addition, the collision of the blood flow from the extracorporeal membrane oxygenator and the blood flow from heart 81 causes the problem that oxygenated blood 9b from the extracorporeal membrane oxygenator is not sufficiently supplied to brain 82.

[0023] In contrast, the antegrade blood infusion cannula of the present invention solves the problems of conventional retrograde blood infusion, as explained below. Figure 11 shows an image of the antegrade blood infusion cannula of the present invention in use. For convenience of explanation, the cannula itself is not shown in Figure 11. 11 , in the antegrade blood infusion cannula of the present invention, the tip of the cannula is inserted up to the position of the ascending aorta 93, and blood 9a passing through the cannula is sent to the position of the ascending aorta 93 and then ejected antegrade. As a result, the ejected blood 9b is sent through the aortic arch 92, the descending aorta 91, the right subclavian artery 94, the right common carotid artery 95, the left common carotid artery 96, and the left subclavian artery 97 without colliding with blood 9c sent from the heart 81, and blood 9b is then supplied to the brain 82. This reduces the workload on the heart and allows oxygenated blood from the extracorporeal membrane oxygenator to be smoothly supplied to the entire body, including the brain 82.

[0024] An example of an embodiment of the present invention will be described in detail below with reference to the drawings. Note that the scope of the present invention is not limited to the following examples and illustrated examples, and many modifications and variations are possible. [Example]

[0025] FIG. 1 shows an external view of an antegrade blood transfer cannula according to a first embodiment. The tip of the antegrade blood transfer cannula 10 is placed in the ascending aorta, and blood supplied from an extracorporeal membrane oxygenator is transferred antegradely from the ascending aorta. The antegrade blood transfer cannula 10 comprises an antegrade blood return tube 1 and a blood transfer tube 4. A guidewire hole 7 (see FIG. 2) extending longitudinally is provided at approximately the center of the axis of the tip of the antegrade blood return tube 1, and a guidewire tube 5 is disposed in the hole, functioning as a guidewire lumen. In FIG. 1, a guidewire 50 is inserted through the guidewire tube 5. The blood transfer tube 4 is a tube provided at the base end that connects to the extracorporeal membrane oxygenator, and has an outer diameter of 11 to 15 Fr (French catheter scale). This is smaller than the outer diameter of blood transfer tubes typically used in extracorporeal membrane oxygenators (approximately 14 to 18 Fr). Here, Fr is a unit indicating the outer diameter of tubes such as catheters, and the outer diameter of a 1 Fr circular catheter is 1 / 3 of a millimeter. The antegrade blood return tube 1 reverses the blood flow from retrograde to antegrade and directs it toward the base end, and is closed at the tip end, with a louver 2 formed by a plurality of fins.

[0026] Fig. 2 shows a perspective view of the antegrade blood return tube of the first embodiment. As shown in Fig. 2, the antegrade blood return tube 1 comprises a distal tapered portion 11 provided on the distal end side and a trunk portion 12 provided on the proximal end side, and the distal tapered portion 11 and the trunk portion 12 are integrally molded.

[0027] Fig. 3 shows a right side view of the antegrade blood return tube of the first embodiment, and Fig. 4 shows an external view of the antegrade blood return tube of the first embodiment, where (1) shows a front view and (2) shows a rear view. As shown in FIG. 3, the distal tapered portion 11 is composed of a distal portion 11a and fins 2a, and the body portion 12 is composed of fins (2b to 2f) and a cylindrical portion 12a. The proximal end of the distal portion 11a, the fins (2a to 2f), and the distal end of the cylindrical portion 12a form a louver 2. More specifically, the proximal end of the distal portion 11a and the fins 2a form a part of the louver 2 provided on the proximal side of the distal tapered portion 11, and the fins (2b to 2f) and the distal end of the cylindrical portion 12a form a part of the louver 2 provided on the distal side of the body portion 12. As shown in FIG. 4(1), the louver 2 is supported by a total of four beams (3a to 3d) provided at approximately 90° intervals in the circumferential direction of the antegrade blood return tube 1 from the distal portion 11a to the cylindrical portion 12a in the longitudinal direction of the antegrade blood return tube 1. This prevents buckling of the antegrade blood return tube 1 when the antegrade blood transfer cannula 10 is inserted into the body. Furthermore, by using thin fins, the cannula can be made flexible, and the fins (2a to 2f) contract in diameter due to an external force when the cannula is inserted, thereby reducing the resistance to insertion into the body. A guidewire lumen 7 is provided at the distal end 11a. As shown in FIG. 4(2), an inner cavity 6 is provided at the proximal end, and blood sent from the blood sending tube 4 is discharged from a blood return path 6a, which is an antegrade blood return path. The guidewire lumen 7 has an inner diameter that is compatible with a guidewire having an outer diameter of 0.035 inches (0.889 mm). Although not shown here, a guidewire tube is inserted through the inner cavity 6 and the guidewire lumen 7 and connected to the guidewire lumen 7.

[0028] FIG. 5 is an explanatory diagram of a louver, where (1) is an explanatory diagram of the fins that make up the louver, and (2) is an image diagram of the fins combined. As shown in FIG. 5(1) or (2), the structure of the fins and louvers will be described using the fins (2b, 2c) as an example, but the description here can also be applied to the fins (2a, 2d to 2f), the base end of the tip portion 11a, and the tip end of the cylindrical portion 12a. Furthermore, the description of the fin structure, except for the fact that the outer surface portion 8b is inversely tapered, can also be applied to Example 2. For ease of explanation, the beam portions (3a to 3d) that support the fins (2b, 2c) are not shown. As shown in Figure 5(1), fin 2b is composed of an inner surface portion 8a, an outer surface portion 8b, an inner tapered portion 8c, and an outer tapered portion 8d. The interior of the approximately truncated cone is hollow, with a top circle 13a and a bottom circle 13b each opening. The outer surface portion 8b is the outer edge of the outer surface of fin 2b. As shown in Figure 5(2), fins 2b and 2c are arranged with a gap between them, forming a blood return path 6a between the inner tapered portion 8c of fin 2b and the outer tapered portion 8d of fin 2c. Blood 9 is discharged from this blood return path 6a, enabling antegrade blood transfer.

[0029] 9A and 9B are explanatory diagrams of the function of the antegrade blood transfer cannula of the first embodiment, where (1) shows a cannula of a comparative example and (2) shows the antegrade blood transfer cannula of Example 1. The cannula 100 of the comparative example shown in Fig. 9A is the cannula of Patent Document 1, in which blood 9 is released from a blood release hole 301 provided in an outer tube 300. The outer tube 300 has an inwardly facing protruding edge 302 formed thereon to guide the blood 9, but the inwardly facing protruding edge 302 is merely formed on the edge of the hole near the base end of the tube. For example, taking the blood release hole 301 at region B2 as an example, the edge of the hole near the tip of the tube does not have a mechanism for guiding the release of blood in the antegrade direction, resulting in a problem of insufficient guidance in the antegrade direction. In contrast, in the antegrade blood transfer cannula 10 of Example 1, for example, as shown in portion B3 of Figure 9 (2), the fins 2d are provided so as to cover the outside of the fins 2e, so that the blood 9 can be effectively guided in the antegrade direction. Furthermore, unlike the cannula 100 of the comparative example, where blood discharge holes 301 are not formed at regular intervals, the fins (2e to 2f) and the cylindrical portion 12a are provided continuously, so that multiple antegrade blood return paths can be provided at short intervals, and the blood can be guided in the antegrade direction more efficiently.

[0030] 6A and 6B are cross-sectional views of the antegrade blood return tube of the first embodiment, where (1) is the AA cross-sectional view shown in FIG. 3, and (2) is an enlarged image of region B1 shown in FIG. 6A. As shown in FIG. 6A, the fins (2b to 2f) and the cylindrical portion 12a all have the same outer diameter φ1. In contrast, the inner diameters of the distal end 11a, fins (2a to 2f), and inner surface 8a of the cylindrical portion 12a that constitute the louver 2 are gradually increased from the distal end to the proximal end of the antegrade blood return tube 1, as can be seen from, for example, the inner diameter φ2 of the fin 2a, the inner diameter φ3 of the fin 2c, and the inner diameter φ4 of the fin 2f. In the tip tapered portion 11, the thickness of the beam portion is increased from the tip side to the base end side, thereby preventing buckling of the tip tapered portion 11 of the antegrade blood return tube 1 in response to resistance when inserting the antegrade blood return tube 1 into the body.

[0031] 6(2), in the louver 2, the outer surface portion 8b provided on the fins (2b to 2f) provided on the body portion 12 is provided in a reverse tapered shape with an inward angle θ relative to the longitudinal direction of the antegrade blood return tube 1 shown by the dashed line. If the angle θ is less than 10°, the diameter of the corner portion 8e approaches the outer diameter φ1 of the cylindrical portion 12a, making it more likely to damage the inner wall of the blood vessel. If the angle θ exceeds 30°, the length of the inner tapered portion 8c becomes shorter, reducing the ability to guide blood in the antegrade direction. Therefore, it is preferable that the angle θ is 10 to 30°, and in this embodiment, the angle θ is 22.5°. This makes it possible to prevent the corners 8e of the fins (2b to 2f) from coming into contact with and damaging the inner wall of the patient's blood vessel (not shown) when the antegrade blood transfer cannula 10 is removed. In contrast, in the louver 2, the base end side end of the tip portion 11a provided on the tip tapered portion 11 and the outer surface portion 8b provided on the fin 2a are not provided in a reverse tapered shape angled inward with respect to the longitudinal direction of the tapered surface of the tip tapered portion 11 shown by the dashed line in Fig. 6(1). This is because the outer diameter of the tip tapered portion 11 is set so that it becomes thinner from the base end side to the tip side, and therefore there is little need to provide a mechanism to prevent snagging similar to that of the fins (2b to 2f). The angle formed by the inner tapered portion 8c or the outer tapered portion 8d of the fins (2a to 2f) and the axial direction of the antegrade blood return tube 1 is set to 20 to 40° from the viewpoints of preventing buckling of the tip tapered portion 11 due to resistance to insertion of the cannula into the blood vessel and improving the performance of guiding blood in the antegrade direction. Therefore, the angle formed by the blood return path 6a and the axial direction of the antegrade blood return tube 1 is also set to 20 to 40°.

[0032] Next, the structure of the beams (3a to 3d) will be described. FIG. 7 is an explanatory diagram of the beams. As shown in FIG. 7, the beams (3a, 3b) are provided so as to be thicker from the portion supporting the fin 2a or fin 2f toward the portion supporting the fin 2b, and are provided so as to support the entire fins (2a to 2f) from the inner surface portion 8a to the outer surface portion 8b. This not only improves the strength of the antegrade blood transfer cannula 1, but also effectively prevents the outer edges of the outer surfaces of the fins (2a to 2f) from catching on the inner wall of the blood vessel and damaging the inner wall of the blood vessel. The same structure applies to the beams (3c, 3d).

[0033] Fig. 8 shows an image of the antegrade blood return cannula of the first embodiment in use. As shown in Fig. 8, a guidewire tube 5 is inserted into the inner space 6 and the guidewire hole 7 of the antegrade blood return tube 1 and connected to the guidewire hole 7. Blood return paths 6a, which are antegrade blood return paths, are provided between the tip portion 11a and the fin 2a, between the fin 2a and the fin 2b, between the fin 2b and the fin 2c, between the fin 2c and the fin 2d, between the fin 2d and the fin 2e, between the fin 2e and the fin 2f, or between the fin 2f and the cylindrical portion 12a. Furthermore, the tip portion 11a, the fins (2a to 2f), and the cylindrical portion 12a are supported by beam portions (3a to 3d), so that a total of 28 blood return paths 6a are formed. As mentioned above, the inner space of the antegrade blood return tube 1 is designed so that its diameter gradually increases from the tip end to the base end, so that blood 9 is stably ejected in the antegrade direction from either blood return path 6a. [Example]

[0034] Figure 10 shows a right side view of the antegrade blood return tube of the second embodiment. As shown in Figure 10, the antegrade blood return tube 1a comprises a distal tapered portion 110 provided on the distal end side and a trunk portion 120 provided on the proximal end side, and the distal tapered portion 110 and the trunk portion 120 are integrally molded. The tip tapered portion 110 is composed of a tip portion 110a and fins 20a, and the body portion 120 is composed of fins (20b to 20f) and a cylindrical portion 120a. The base end portion of the tip portion 110a, the fins (20a to 20f), and the tip end portion of the cylindrical portion 120a form the louver 20. More specifically, the base end portion of the tip portion 110a and the fins 20a form a part of the louver 20 provided on the base end side of the tip tapered portion 110, and the fins (20b to 20f) and the tip end portion of the cylindrical portion 120a form a part of the louver 20 provided on the tip side of the body portion 120. The antegrade blood return tube 1a of the second embodiment differs from the antegrade blood return tube 1 of the first embodiment in that the outer surface portions 8b provided on the fins (20c to 20f) provided on the body portion 120 of the louver 20 are arranged substantially parallel to the longitudinal direction of the antegrade blood return tube 1a indicated by the dashed line. This allows the length of the inner tapered portions 8c provided on the fins (20c to 20f) to be longer than the fins (2c to 2f) of the antegrade blood return tube 1, thereby improving the ability to guide blood in the antegrade direction. The other configurations are the same as those of the antegrade blood return tube 1 of the first embodiment. [Example]

[0035] Fig. 13 shows a right side view of the antegrade blood return tube of the third embodiment. As shown in Fig. 13, the antegrade blood return tube 1b is composed of a distal tapered portion 111 provided on the distal end side and a trunk portion 121 provided on the proximal end side, and the distal tapered portion 111 and the trunk portion 121 are integrally molded. The tip tapered portion 111 is composed of a tip portion 111a and fins 21a, and the body portion 121 is composed of fins (21b to 21f) and a cylindrical portion 121a. The base end portion of the tip portion 111a, the fins (21a to 21f), and the tip end portion of the cylindrical portion 121a form the louvers 21. More specifically, the base end portion of the tip portion 111a and the fins 21a form a part of the louvers 21 provided on the base end side of the tip tapered portion 111, and the fins (21b to 21f) and the tip end portion of the cylindrical portion 121a form a part of the louvers 21 provided on the tip side of the body portion 121.

[0036] Unlike the antegrade blood return tube 1 of the first embodiment, the antegrade blood return tube 1b of the third embodiment has a blood return path 6b, which is a lateral blood return path, provided between the tip portion 111a and the fin 21a. The tip portion 111a, the fins (21a to 21f), and the cylindrical portion 121a are supported by four beams (not shown), resulting in a total of four blood return paths 6b. The lateral blood return path allows blood to be ejected in a direction perpendicular to the long axis of the cannula, making it possible to send blood to the coronary artery without retrograde blood return. Furthermore, similar to the antegrade blood return tube 1, a blood return path 6a, which is a antegrade blood return path, is provided between fin 21a and fin 21b, between fin 21b and fin 21c, between fin 21c and fin 21d, between fin 21d and fin 21e, between fin 21e and fin 21f, or between fin 21f and cylindrical portion 121a, thereby enabling antegrade blood return. The other configurations are the same as those of the antegrade blood return tube 1 of the first embodiment. [Example]

[0037] Fig. 14 shows a right side view of the antegrade blood return tube of the fourth embodiment. As shown in Fig. 14, the antegrade blood return tube 1c comprises a distal tapered portion 112 provided on the distal end side and a trunk portion 122 provided on the proximal end side, and the distal tapered portion 112 and the trunk portion 122 are integrally molded. The tip tapered portion 112 is composed of a tip portion 112a and fins (22a, 22b), and the body portion 122 is composed of fins (22c to 22f) and a cylindrical portion 122a. The base end portion of the tip portion 112a, the fins (22a to 22f), and the tip end portion of the cylindrical portion 122a form the louvers 22. More specifically, the base end portion of the tip portion 112a and the fins (22a, 22b) form a part of the louvers 22 provided on the base end side of the tip tapered portion 112, and the fins (22c to 22f) and the tip end portion of the cylindrical portion 122a form a part of the louvers 22 provided on the tip side of the body portion 122.

[0038] The antegrade blood return tube 1c of the fourth embodiment differs from the antegrade blood return tube 1b of the third embodiment in that blood return paths 6b, which are lateral blood return paths, are provided not only between the tip portion 112a and the fin 22a but also between the fins 22a and 22b. The tip portion 112a, the fins (22a to 22f), and the cylindrical portion 122a are supported by four beams (not shown), resulting in a total of eight blood return paths 6b. Because the lateral blood return paths allow blood to be ejected in a direction perpendicular to the longitudinal axis of the cannula, providing more blood return paths 6b than the antegrade blood return tube 1b makes it possible to more effectively send blood to the coronary artery without causing retrograde blood return. Furthermore, between fin 22b and fin 22c, between fin 22c and fin 22d, between fin 22d and fin 22e, between fin 22e and fin 22f, or between fin 22f and cylindrical portion 122a, a blood return path 6a, which is a antegrade blood return path, is provided, similar to the antegrade blood return tube 1, so that antegrade blood flow is possible. The other configurations are the same as those of the antegrade blood return tube 1 of the first embodiment. [Industrial Applicability]

[0039] The present invention is useful as a cannula for use in an extracorporeal circulatory assist device. [Explanation of symbols]

[0040] 1,1a~1c Foregrade blood return tube 2,20~22 louvers 2a~2f, 20a~20f, 21a~21f, 22a~22f Fins 3,3a~3d beam part 4 Blood Transfer Tubes 5 Guidewire tube 6 Inner sky 6a,6b Blood return route 7 Guidewire hole 8a inner surface 8b External part 8c Inner tapered part 8d Outer tapered part 8e corner 9,9a~9c blood 10 Antegrade Blood Infusion Cannula 11,110~112 Tapered tip 11a,110a,111a,112a Tip 12,120~122 Torso 12a, 120a, 121a, 122a Cylindrical part 13a, 13b yen 50 Guidewire 81 Heart 82 Brain 91 Descending aorta 92 Aortic arch 93 Ascending aorta 94 Right subclavian artery 95 Right common carotid artery 96 Left common carotid artery 97 Left subclavian artery 98 Right coronary artery 99 Left coronary artery 100 cannula 300 outer tube 301 Blood release hole 302 Inward protruding edge A cross section B1~B3 part θ angle φ1~φ3 diameter

Claims

1. A cannula whose distal end is placed in the ascending aorta and which sends blood supplied from an extracorporeal membrane oxygenator in an antegrade manner from the ascending aorta, a blood transfer tube provided on the proximal end side of the cannula and connectable to the extracorporeal membrane oxygenator; An antegrade blood transfer cannula for an extracorporeal membrane oxygenator is provided with a non-retrograde blood return tube, in which a tapered tip portion is formed at the tip side of the cannula, the diameter of which decreases toward the tip, and at least one of a antegrade blood return path that reverses the blood from retrograde to antegrade and directs it toward the base end, or a lateral blood return path that directs the blood from retrograde to lateral, is provided at the tapered tip portion.

2. The non-retrograde blood return tube is The tip side is closed, 2. The antegrade blood infusion cannula for an extracorporeal membrane oxygenation lung according to claim 1, wherein the interior of the truncated cone is hollow, and the fins have a shape with an opening at each of the top and bottom circles, the diameter of the top increasing from the tip end to the base end of the cannula, and the diameter of the bottom increasing or remaining constant, and the fins are provided in plurality at intervals along the longitudinal direction of the cannula.

3. The non-retrograde blood return tube is provided with a beam portion that holds the fin, 3. The antegrade blood return cannula for an extracorporeal membrane oxygenator according to claim 2, wherein a gap formed by the fin and the beam portion serves as the antegrade blood return path or the lateral blood return path.

4. 4. The antegrade blood infusion cannula for extracorporeal membrane oxygenation according to claim 3, wherein at least the outer surfaces of the fins are supported by the beams.

5. 5. The antegrade blood infusion cannula for extracorporeal membrane oxygenation according to claim 4, wherein the outer edges of the outer surfaces of the fins are formed in a reverse tapered shape.

6. 4. The antegrade blood transfer cannula for an extracorporeal membrane oxygenator according to claim 3, wherein the beam portions are provided at regular intervals in the circumferential direction of the non-retrograde blood return tube.

7. 6. The antegrade blood infusion cannula for extracorporeal membrane oxygenation according to claim 5, wherein the angle formed by the outer edge of the outer surface and the axial direction of the cannula is 10 to 30 degrees.

8. 8. The antegrade blood infusion cannula for an extracorporeal membrane oxygenator according to claim 1, further comprising a guide wire tube provided approximately in the center of the axis of the cannula and through which a guide wire is inserted from the base end to the tip end.

9. An antegrade blood return cannula for an extracorporeal membrane oxygenator according to any one of claims 1 to 7, wherein a antegrade blood return path that reverses the blood from retrograde to antegrade and directs it toward the base end is further provided in the trunk of the non-retrograde blood return tube.

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