Antegrade blood supply cannula

Abstract

Provided is a cannula capable of safely and effectively supplying blood in an antegrade manner from the ascending aorta while having a smaller diameter. The cannula comprises an antegrade blood return tube 1 and a blood supply tube 4. The antegrade blood return tube 1 has a distal end part having a guide wire opening that extends in the longitudinal direction substantially along the central axis of the distal end part. A guide wire tube 5 is placed through the opening. A guide wire 50 is inserted through the guide wire tube 5. The antegrade blood return tube 1 comprises a distal tapered portion on the distal side and a body portion on the proximal side, and the distal tapered portion and the body portion are integrally molded. The distal tapered portion comprises a tip part and fins, and the body portion comprises fins and a tubular part. The proximal end of the tip part, the fins, and the distal end of the tubular part forms a louver 2. The louver 2 is supported by a total of four beams extending from the tip part to the tubular part in the longitudinal direction of the antegrade blood return tube 1.

Description

Antegrade blood infusion cannula

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

[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 support devices include the intracardiac pump catheter for circulatory support (IMPELLA (registered trademark)) and percutaneous cardiopulmonary support (ECMO (PCPS)). IMPELLA can reduce cardiac load, but has the problem of not being able to oxygenate the heart and being subject to strict facility standards. In contrast, ECMO is widely used because it can oxygenate the heart and is not subject to facility restrictions, but it has the major problem of increasing cardiac load due to retrograde blood infusion. In addition, because a large-diameter cannula must be placed, vascular complications associated with cannula placement are also a major problem.

[0004] First, regarding the issue of increased cardiac strain associated with retrograde blood flow, ECMO is a device that supplies oxygenated blood to vital organs, particularly the brain. However, the high flow rate of blood sent in the opposite direction from the heart places a strain on the heart. This may delay the recovery of cardiac function. Regarding the second issue of vascular complications associated with large-diameter cannulas, the incidence of lower limb ischemia after insertion of an ECMO cannula from the femoral artery is said to be approximately 10-70%. Lower limb ischemia can lead to compartment syndrome and 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 survived to hospital discharge, even in conditions that would normally result in death. However, a significant number of patients (45%) died from complications associated with long-term ECMO placement, such as bleeding (33%) and sepsis (22%) (see, for example, Non-Patent Document 1).

[0005] In recent years, a technique called "ECPELLA" that combines IMPELLA and ECMO has been used, 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 still apply.

[0006] A cannula capable of antegrade blood transfer is known as a blood transfer cannula used in extracorporeal circulation using a heart-lung machine (see Patent Document 1). This cannula consists of an outer tube and an inner tube. Blood passes through an annular return flow path formed between the inner tube and the outer tube, whose distal end is blocked, and is then discharged antegrade into the aorta from a blood discharge hole in the outer tube. However, the cannula in Patent Document 1 has an inward-facing protrusion on the edge of each blood discharge hole as a mechanism for guiding the blood discharge in the antegrade direction. However, the inward-facing protrusion is only formed on the hole edge near the base end of the tube; the hole edge near the distal end of the tube does not have a mechanism for guiding the blood discharge in the antegrade direction, resulting in insufficient antegrade guidance. Furthermore, when the tube is removed, the hole edge near the distal end of the tube abuts against the inner wall of the blood vessel, potentially damaging the vessel's 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 structurally difficult to make the cannula thinner, and it does not have a mechanism for inserting a guide wire, making it less convenient.

[0007] JP 2015-23970 A

[0008] Alberto Zangrillo et al., "A meta-analysis of complications and mortality of extracorporeal membrane oxygenation", Crit Care Resusc. 2013 Sep;15(3):172-8.

[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.

[0010] To solve the above problems, the present invention provides an antegrade blood transfer cannula, whose distal end is positioned in the ascending aorta and which transfers blood supplied from an extracorporeal membrane oxygenator in an antegrade direction from the ascending aorta. The cannula includes a blood transfer tube connected to the proximal end of the cannula and connectable to the extracorporeal membrane oxygenator, and a non-retrograde blood return tube formed at the distal end of the cannula with a tapered distal end whose diameter decreases toward the distal end. The non-retrograde blood return tube provides at least one of an antegrade blood return path that reverses the blood flow from retrograde to antegrade and returns it toward the proximal end, or a lateral blood return path that returns the blood from retrograde to lateral, on the proximal end of the tapered distal end. The inclusion of the non-retrograde blood return tube prevents the blood supplied from the extracorporeal membrane oxygenator from colliding with the blood from the heart, thereby effectively reducing cardiac load. A non-retrograde blood return tube is a tube that has at least one of a antegrade blood return path and a lateral blood return path, and in this specification, a blood return tube that has a antegrade blood return path in at least part of the tube is also referred to as a antegrade blood return tube.

[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 port. 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 oxygenation (ECMO) device.

[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] When the gap formed by the fins and 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 the angle is less than 25°, the axial length of the beams holding the fins increases, making the cannula more susceptible to buckling at the tapered distal end due to resistance to insertion into the blood vessel. Furthermore, if the angle exceeds 40°, the length of the antegrade blood return path formed between the fins decreases, reducing the ability to guide blood in the antegrade direction. On the other hand, when the gap formed by the fins and beams 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 to approximately 90°, blood can be ejected perpendicular to the long axis of the cannula, allowing blood to be sent to the coronary artery without retrograde blood return. Note that "the distal end is closed" means that the blood flow path is closed, and the distal end of the guidewire tube (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 more likely to be 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.

[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.

[0021] 1. Appearance diagram of the antegrade blood return cannula of the first embodiment; 2. Perspective view of the antegrade blood return tube of the first embodiment; 3. Right side view of the antegrade blood return tube of the first embodiment; 4. Front and rear views of the antegrade blood return tube of the first embodiment; 5. Explanatory diagram of the louver; 6. Cross-sectional image of the antegrade blood return tube of the first embodiment; 7. Explanatory diagram of the beam portion; 8. Usage image of the antegrade blood return cannula of the first embodiment; 9. Functional diagram of the antegrade blood return cannula of the first embodiment; 10. Right side view of the antegrade blood return tube of the second embodiment; 11. Usage image of the antegrade blood return cannula of the present invention; 12. Usage image of a conventional blood return cannula; 13. Cross-sectional image of the antegrade blood return tube of the third embodiment; 14. Cross-sectional image of the antegrade blood return tube of the fourth embodiment

[0022] First, a description will be given of an example of how a conventional blood transfer cannula is used. Figure 12 shows an example of how a conventional blood transfer cannula is used. In conventional retrograde blood transfer, blood 9b is sufficiently oxygenated and transferred in an extracorporeal membrane oxygenator (not shown) 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 conventional retrograde blood transfer, blood 9b collides with blood 9c pumped from the heart 81 at the ascending aorta 93, causing cardiac strain. Furthermore, the collision of the blood flow from the extracorporeal membrane oxygenator and the blood flow from the heart 81 results in an insufficient supply of oxygenated blood 9b from the extracorporeal membrane oxygenator to the brain 82.

[0023] In contrast, the antegrade blood infusion cannula of the present invention solves the problems of conventional retrograde blood infusion, as will be explained below. Fig. 11 shows an image of the use of the antegrade blood infusion cannula of the present invention. For convenience of explanation, the cannula itself is not shown in Fig. 11. As shown in Fig. 11, with 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. Therefore, blood 9a passing through the cannula is sent to 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 ejected from the heart 81, and blood 9b is finally supplied to the brain 82. This reduces the cardiac load and allows oxygenated blood flow 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.

[0025] FIG. 1 shows an external view of a first embodiment of an antegrade blood transfer cannula. The distal end 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 longitudinally extending guidewire hole 7 (see FIG. 2) is provided at the approximate axial center of the distal end of the antegrade blood return tube 1, through which a guidewire tube 5 is disposed, functioning as a guidewire lumen. In FIG. 1, a guidewire 50 is inserted through the guidewire tube 5. The blood transfer tube 4 is provided at the proximal end of the extracorporeal membrane oxygenator and connects to the extracorporeal membrane oxygenator. Its outer diameter is 11 to 15 Fr (French catheter scale). Its smaller diameter is evident compared to the outer diameter of blood transfer tubes commonly used in extracorporeal membrane oxygenators (approximately 14 to 18 Fr). Here, Fr is a unit of measurement for 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 proximal end. The distal end is closed, and a louver 2 is formed by multiple 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. FIG. 4 shows external views of the antegrade blood return tube of the first embodiment, with (1) showing a front view and (2) showing a rear view. As shown in FIG. 3, the distal tapered portion 11 is composed of a distal end portion 11a and a fin 2a, and the trunk portion 12 is composed of fins (2b to 2f) and a cylindrical portion 12a. The proximal end of the distal end 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 portion of the distal end portion 11a and the fin 2a form a part of the louver 2 provided on the proximal side of the distal tapered portion 11, and the distal end portion of the fins (2b to 2f) and the cylindrical portion 12a form a part of the louver 2 provided on the distal side of the trunk portion 12. As shown in FIG. 4(1), the louver 2 is supported by a total of four beams (3a-3d) arranged at approximately 90° intervals around the circumferential direction of the antegrade blood return tube 1, from the distal end 11a to the cylindrical portion 12a in the longitudinal direction of the antegrade blood return tube 1. This prevents the antegrade blood return tube 1 from buckling when the antegrade blood transfer cannula 10 is inserted into the body. Furthermore, the thin fins provide flexibility to the cannula, allowing the fins (2a-2f) to contract in diameter due to external force during cannula insertion, thereby reducing insertion resistance within the body. A guidewire hole 7 is provided in the distal end 11a. Furthermore, as shown in FIG. 4(2), an internal cavity 6 is provided on the proximal end side, and blood transferred from the blood transfer tube 4 is discharged from the blood return path 6a, which is the antegrade blood return path. The guidewire hole 7 has an inner diameter that is compatible with a guidewire having an outer diameter of 0.035 inches (0.889 mm), and although not shown here, a guidewire tube is inserted into the inner space 6 and the guidewire hole 7 and connected to the guidewire hole 7.

[0028] FIG. 5 is an explanatory diagram of a louver, (1) is an explanatory diagram of fins constituting the louver, and (2) shows an image diagram of a combination of fins. As shown in FIG. 5(1) or (2), here, the structure of the fins and the louver will be described by taking the fins (2b, 2c) as an example, and the description here is also applicable to the fins (2a, 2d to 2f) and the base end side end portion of the tip portion 11a and the tip end side end portion of the cylindrical portion 12a. In addition, the description regarding the structure of the fins other than the point where the outer surface portion 8b is reversely tapered is also applicable to the second embodiment. For the sake of convenience of explanation, the beam portions (3a to 3d) that support the fins (2b, 2c) are not shown. As shown in FIG. 5(1), the 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, and the inside of a substantially frustum of a cone is hollow, and the circle 13a on the top surface and the circle 13b on the bottom surface are each in an open shape. The outer surface portion 8b is the outer edge of the outer side surface of the fin 2b. As shown in FIG. 5(2), when the fin 2b and the fin 2c are arranged with a gap therebetween, a blood return path 6a is formed between the inner tapered portion 8c of the fin 2b and the outer tapered portion 8d of the fin 2c. By discharging the blood 9 from such a blood return path 6a, forward blood delivery becomes possible.

[0029] FIG. 9 is a functional explanatory diagram of the forward blood delivery cannula of the first embodiment, (1) shows a cannula of a comparative example, and (2) shows the forward blood delivery cannula of Example 1. The cannula 100 of the comparative example shown in FIG. 9(1) is the cannula of Patent Document 1, and the blood 9 is discharged from a blood discharge hole 301 provided in the outer tube 300. An inward protruding edge portion 302 is formed on the outer tube 300, which is a structure for guiding the blood 9, but the inward protruding edge portion 302 is only formed at the hole edge closer to the base end side of the tube. For example, taking the blood discharge hole 301 at site B ２ as an example, since there is no mechanism for guiding the blood discharge direction in the forward direction at the hole edge closer to the tip end side of the tube, there is a problem that the forward direction guiding is not sufficient. On the other hand, in the forward blood delivery cannula 10 of Example 1, for example, at site B in FIG. 9(2) ３As shown in Fig. 1, fins 2d are provided to cover the outside of fins 2e, so blood 9 can be effectively guided in the antegrade direction. Furthermore, unlike cannula 100 of the comparative example, where blood discharge holes 301 are formed at regular intervals, fins (2e to 2f) and cylindrical portion 12a are provided continuously, so multiple antegrade blood return paths can be provided at short intervals, making antegrade guidance more efficient.

[0030] 6A and 6B are cross-sectional images of the antegrade blood return tube of the first embodiment, (1) is a cross-sectional view taken along line A-A in FIG. 3, and (2) is a cross-sectional view of part B in FIG. 6A. １ As shown in FIG. 6(1), the outer diameters of the fins (2b to 2f) and the cylindrical portion 12a are the same, φ １ On the other hand, the inner diameter of the tip portion 11a, the fins (2a to 2f), and the inner surface portion 8a of the cylindrical portion 12a that constitute the louver 2 is, for example, the inner diameter φ of the fin 2a. ２ and the inner diameter φ of the fin 2c ３ , the inner diameter φ of the fin 2f ４ As can be seen from the figure, the diameter gradually increases from the distal end to the proximal end of the antegrade blood return tube 1. Increasing the thickness of the beam portion from the distal end to the proximal end of the distal tapered portion 11 makes it possible to prevent buckling of the distal 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), the outer surface portion 8b of the louver 2 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 broken line. If the angle θ is less than 10°, the diameter of the corner portion 8e becomes smaller than the outer diameter φ of the cylindrical portion 12a. １Approaching the distal end of the louver 2 makes it more likely to damage the inner wall of the blood vessel. Furthermore, exceeding 30° shortens the length of the inner tapered portion 8c, reducing its ability to guide blood in the antegrade direction. Therefore, a preferred angle θ is 10 to 30°. In this embodiment, the angle θ is 22.5°. This prevents the corners 8e of the fins (2b to 2f) from contacting and damaging the inner wall of the patient's blood vessel (not shown) when the antegrade blood transfer cannula 10 is removed. In contrast, the proximal end of the distal end 11a of the distal tapered portion 11 and the outer surface 8b of the fin 2a are not reverse-tapered, angled inward relative to the longitudinal direction of the tapered surface of the distal end tapered portion 11, as shown by the dashed line in FIG. 6(1). This is because the outer diameter of the distal end tapered portion 11 tapers from the proximal end to the distal end, reducing the need for 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 distal end 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 become thicker from the portion supporting fin 2a or fin 2f toward the portion supporting fin 2b, and are provided so as to support the entire fins (2a to 2f) from the inner surface 8a to the outer surface 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] Figure 8 shows an image of the antegrade blood return cannula of the first embodiment in use. As shown in Figure 8, a guidewire tube 5 is inserted into the inner space 6 and 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 fin 2a, between fin 2a and fin 2b, between fin 2b and fin 2c, between fin 2c and fin 2d, between fin 2d and fin 2e, between fin 2e and fin 2f, or between 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.

[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 section 110 provided on the distal end side and a trunk section 120 provided on the proximal end side, with the distal tapered section 110 and trunk section 120 being integrally molded. The distal tapered section 110 is composed of a distal section 110a and fins 20a, and the trunk section 120 is composed of fins (20b to 20f) and a cylindrical section 120a. The proximal end of the distal section 110a, the fins (20a to 20f), and the distal end of the cylindrical section 120a form a louver 20. More specifically, the proximal end of the distal portion 110a and the fin 20a form part of the louver 20 provided on the proximal side of the distal tapered portion 110, and the distal end of the fins (20b-20f) and the distal end of the cylindrical portion 120a form part of the louver 20 provided on the distal side of the trunk 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 portion 8b of the louver 20 provided on the fins (20c-20f) provided on the trunk portion 120 is arranged substantially parallel to the longitudinal direction of the antegrade blood return tube 1a, as indicated by the dashed line. This allows the length of the inner tapered portion 8c provided on the fins (20c-20f) to be longer than the fins (2c-2f) of the antegrade blood return tube 1, thereby improving the ability to guide blood in the antegrade direction. The remaining configuration is the same as that of the antegrade blood return tube 1 of the first embodiment.

[0035] Figure 13 shows a right side view of the antegrade blood return tube of the third embodiment. As shown in Figure 13, the antegrade blood return tube 1b comprises a distal tapered portion 111 provided on the distal end side and a trunk portion 121 provided on the proximal end side, with the distal tapered portion 111 and trunk portion 121 being integrally molded. The distal tapered portion 111 is composed of a distal portion 111a and fins 21a, and the trunk portion 121 is composed of fins (21b to 21f) and a cylindrical portion 121a. The proximal end of the distal portion 111a, the fins (21a to 21f), and the distal end of the cylindrical portion 121a form a louver 21. More specifically, the base end portion of the tip portion 111a and the fin 21a form part of the louver 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 part of the louver 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, between the distal end 111a and the fin 21a. The distal end 111a, the fins (21a-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 paths allow blood to be ejected perpendicular to the longitudinal axis of the cannula, enabling blood to be sent to the coronary artery without retrograde blood return. Similar to the antegrade blood return tube 1, the blood return path 6a is provided between the fins 21a and 21b, between the fins 21b and 21c, between the fins 21c and 21d, between the fins 21d and 21e, between the fins 21e and 21f, or between the fins 21f and the cylindrical portion 121a, enabling antegrade blood return. The other configurations are the same as those of the antegrade blood return tube 1 of the first embodiment.

[0037] Figure 14 shows a right side view of the antegrade blood return tube of the fourth embodiment. As shown in Figure 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, with the distal tapered portion 112 and trunk portion 122 being integrally molded. The distal tapered portion 112 comprises a distal portion 112a and fins (22a, 22b), and the trunk portion 122 comprises fins (22c to 22f) and a cylindrical portion 122a. The proximal end of the distal portion 112a, the fins (22a to 22f), and the distal end of the cylindrical portion 122a form a louver 22. More specifically, the base end portion of the tip portion 112a and the fins (22a, 22b) form part of the louver 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 part of the louver 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, the blood return path 6a, which is a antegrade blood return path, is provided between the fins 22b and 22c, between the fins 22c and 22d, between the fins 22d and 22e, between the fins 22e and 22f, or between the fins 22f and the cylindrical portion 122a, similarly to the antegrade blood return tube 1, enabling antegrade blood return. Note that the other configurations are the same as those of the antegrade blood return tube 1 of the first embodiment.

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

[0040] 1, 1a to 1c Antegrade blood return tube 2, 20 to 22 Louvers 2a to 2f, 20a to 20f, 21a to 21f, 22a to 22f Fins 3, 3a to 3d Beam portion 4 Blood return tube 5 Guide wire tube 6 Inner space 6a, 6b Blood return path 7 Guide wire hole 8a Inner surface portion 8b Outer surface portion 8c Inner tapered portion 8d Outer tapered portion 8e Corner portion 9, 9a to 9c Blood 10 Antegrade blood return cannula 11, 110 to 112 Tip tapered portion 11a, 110a, 111a, 112a Tip portion 12, 120 to 122 Body portion 12a, 120a, 121a, 122a Cylindrical portion 13a, 13b Circle 50 Guide wire 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 B １ ~B ３ Part θ Angle φ １ ~φ ３ diameter

Claims

1. A cannula with its tip positioned in the ascending aorta for antegrade blood transfer from an extracorporeal membrane oxygenator, comprising: a blood transfer tube provided on the proximal end of the cannula and connectable to the extracorporeal membrane oxygenator; and a non-retrograde blood return tube having a tapered distal end portion at the distal end of the cannula, the diameter of which decreases toward the distal end, and at least one of an antegrade blood return path that reverses the blood from retrograde to antegrade and directs it toward the proximal end, or a lateral blood return path that directs the blood from retrograde to lateral, provided on the proximal end of the tapered distal end portion.

2. An antegrade blood transfer cannula as described in claim 1, further comprising an antegrade blood return path in the body of the non-retrograde blood return tube, which reverses the blood from retrograde to antegrade and directs it toward the base end.

3. The non-retrograde blood return tube is an antegrade blood return cannula as described in claim 1 or 2, wherein the tip side is closed, the inside of the truncated cone is hollow, and a plurality of fins are provided at intervals along the longitudinal direction of the cannula, with the fins being shaped like a circular opening on both the top and bottom sides, with the diameter of the top side increasing from the tip side to the base end of the cannula and the diameter of the bottom side being constant or increasing, and the fins are provided on the cannula with beams to hold the fins, and the gaps formed by the fins and the beams form the antegrade blood return path or the lateral blood return path.

4. The antegrade blood transfer cannula according to claim 3, wherein at least the outer surfaces of the fins are supported by the beams.

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

6. An antegrade blood transfer cannula as described in claim 3, wherein the beam portions are provided at regular intervals around the circumference of the non-retrograde blood return tube.

7. The antegrade blood transfer cannula 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. An antegrade blood transfer cannula according to claim 1 or 2, further comprising a guidewire tube provided approximately in the center of the axis of the cannula, through which a guidewire is inserted from the base end to the tip end.

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