Connection of a blood flow channel to a cannula

Abstract

The application aims to provide a connection structure of a blood flow channel and a sleeve with high bonding reliability, which comprises a blood flow channel and a sleeve. The blood flow channel comprises a round tube, and a connecting tube section is extended from the end of the round tube near one side of the sleeve. The outer wall of the connecting tube section is in a shape of a tapered column with a large middle diameter and small diameters on both sides. The maximum outer diameter of the connecting tube section is smaller than the outer diameter of the round tube, and the sleeve is sleeved on the outer periphery of the connecting tube section and is bonded by glue. The outer wall of the connecting tube section is in a shape of a tapered column with a large middle diameter and small diameters on both sides, which increases the contact area of the sleeve and the connecting tube section and increases the pulling force between them. When the sleeve is stretched and deformed, the contact surface is subjected to normal pressure and glue shear force, and the normal pressure increases with the increase of the deformation amount of the sleeve at this position, which provides a guarantee for the reliable connection between the sleeve and the blood flow channel.

Description

Technical Field

[0001] This invention relates to the field of hormones in medical devices, specifically to a connection structure between a blood flow channel and a cannula. Background Technology

[0002] A catheter pump can (partially) replace cardiac function, providing hemodynamic support for patients with cardiogenic shock or heart failure. After percutaneous implantation in the heart, an internal motor drives the impeller to rotate, enabling the catheter pump to achieve a pumping flow rate of 2.5-7.0 L / min at a speed of 30,000-60,000 rpm, supporting short-term (days or weeks) or long-term (weeks or months) life-sustaining applications. The proximal and distal ends of the catheter pump cannula are connected to the blood outflow cage and blood inflow cage, respectively. When the pump motor operates, it draws blood from the blood inflow cage, through the cannula, and out of the blood outflow cage. In existing technologies, the connection between the cannula and the blood outflow / inflow cage is generally achieved using epoxy resin adhesive. During use, due to fluid movement, the connection between the cannula and the blood outflow / inflow cage bears a heavy load, making it prone to misalignment, loosening, and thrombosis. In severe cases, it can cause the connection between the cannula and the blood outflow / inflow cage to detach or tear, which is absolutely unacceptable. Summary of the Invention

[0003] The purpose of this invention is to provide a connection structure between a blood flow channel and a cannula with high bonding reliability.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a connection structure between a blood flow channel and a sheath, comprising a blood flow channel and a sheath, the blood flow channel comprising a circular tube, a connecting tube segment extending from the end of the circular tube near the sheath, the outer wall of the connecting tube segment being a conical column with a large diameter in the middle and a small diameter on both sides, the sheath being sleeved on the outer periphery of the connecting tube segment and glued together.

[0005] The connecting tube section includes a first tube section and a second tube section arranged sequentially from the free end of the blood flow channel toward the circular tube. The outer diameter of the first tube section gradually increases from the free end toward the middle and gradually decreases from the middle toward the end of the circular tube. The minimum outer diameter of the first tube section and the second tube section are equal.

[0006] The length of the first pipe section is L1, and the length of the second pipe section is L2. The ratio of L1 to L2 is 1 to 2 to 3.

[0007] The outer edges of both the first and second pipe sections are curved, and the connection is smooth.

[0008] The maximum outer diameter of the connecting pipe section is smaller than the outer diameter of the circular pipe.

[0009] The outer surface of the connecting pipe section is provided with a continuous thread structure.

[0010] The sleeve includes a spring body support and an inner film and an outer film covering the inner and outer sides of the spring body support. The outer film extends to the end of the spring body support, and the inner film extends to a position close to the end of the spring body support, so that at least a portion of the spring body support is directly connected to the connecting pipe section.

[0011] The spring body support is a spiral structure made of shape memory alloy wire and is pre-shaped into a curved shape that conforms to the physiological structure of the human body. The winding density of the shape memory alloy wire at both ends of the spring body support is greater than that of the shape memory alloy wire in the middle position.

[0012] The shape memory alloy wire is selected from one of nickel-titanium alloy, titanium-nickel-copper alloy, titanium-nickel-iron alloy, and titanium-nickel-chromium alloy, and the inner and outer films are each independently selected from one of polyethylene, polyurethane, soft PVC, and thermoplastic elastomer.

[0013] The blood flow channel is for blood to flow into or out of the cage, and the circular tube of the blood flow channel has multiple flow windows along its circumference.

[0014] The above-mentioned solution has at least the following beneficial effects:

[0015] 1. The outer wall of the connecting pipe section is a conical shape with a large diameter in the middle and a small diameter on both sides, which increases the contact area between the sleeve and the connecting pipe section and increases the pull-out force between them;

[0016] 2. When the sleeve is stretched and deformed, the sleeve corresponding to the first pipe section changes from thick to thin, which will increase the normal pressure on the contact surface at the first pipe section, thereby increasing the adhesive shear force at the end face.

[0017] 3. The casing corresponding to the second pipe section changes from thin to thick. The contact surface is subjected to normal pressure and glue shear force. The normal pressure will increase as the deformation of the casing at this point increases.

[0018] 4. The requirements for the mating dimensions of the sleeve and connecting pipe sections are low, the extrusion process of the sleeve has low precision requirements, and the pass rate is high;

[0019] 5. The connection points can be made by a combination of welding and gluing, which together ensure a reliable connection between the cannula and the blood flow channel. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the blood flow channel and cannula.

[0021] Figure 2 for Figure 1 A sectional view;

[0022] Figure 3 This is a diagram showing the external shape of the blood flow channel;

[0023] Figure 4 for Figure 3 A sectional view;

[0024] Figure 5 for Figure 2 A partially enlarged schematic diagram;

[0025] Figure 6 for Figure 4 A partially enlarged schematic diagram;

[0026] Figure 7 This is a drawing of the casing's outline. Detailed Implementation

[0027] To facilitate understanding, we will first define the terms "proximal" and "proximal side" as used below: "proximal" refers to the side closer to the operator / doctor, while "distal" and "distal side" refers to the side farther from the operator / doctor, i.e., the side closer to the heart. The following will combine... Figures 1-7 The present invention will be described in further detail below.

[0028] A connection structure between a blood flow channel and a sheath includes a blood flow channel 10 and a sheath 20. The blood flow channel 10 includes a circular tube 11. A connecting tube segment 12 extends from the end of the circular tube 11 near the sheath 20. The outer wall of the connecting tube segment 12 is a conical column with a large diameter in the middle and a small diameter on both sides. The sheath 20 is sleeved on the outer periphery of the connecting tube segment 12 and glued together.

[0029] Generally, the outer wall of the connecting tube segment 12 of the blood flow channel 10 that we see now is a constant diameter structure. This structure has the following disadvantages: 1. It has very high requirements for the mating dimensions of the sleeve 20 and the connecting tube segment 12. It is necessary to ensure that the extrusion process of the sleeve 20 is very precise, resulting in a low assembly qualification rate; 2. When the sleeve 20 is under tension, the sleeve 20 deforms and thins in a very small area at the end of the connecting tube segment 12, causing the glue between them to peel off. As the tension continues to increase, the glue in the small area will spread to the middle (not simultaneously) and fail. Therefore, the tension that the connection can withstand is very small, which does not meet the component bonding requirements. Moreover, the pull-out force that different products can withstand is extremely unstable, resulting in poor product bonding reliability.

[0030] In this invention, the outer wall of the connecting pipe section 12 is a conical column with a large diameter in the middle and small diameters on both sides, which increases the contact area between the sleeve 20 and the connecting pipe section 12 and increases the pull-out force between them. When the sleeve 20 is under tension, the sleeve 20 fitted around the outer periphery of the connecting pipe section 12 deforms. During the process of changing from thick to thin and from thin to thick, the adhesive peeling is extensive, so it can withstand a very large force and the product bonding reliability is high. The taper of the connecting pipe section 12 plays a certain guiding role in the assembly of the kit, and the requirements for the mating dimensions at the mating point of the sleeve 20 and the connecting pipe section 12 are low. Therefore, the extrusion process precision requirements of the sleeve 20 can be reduced, the assembly qualification rate is high, and the economy is greatly improved.

[0031] As a preferred embodiment of the present invention, such as Figure 5 , Figure 6 As shown, the connecting tube segment 12 includes a first tube segment 121 and a second tube segment 122 arranged sequentially from the free end of the blood flow channel 10 towards the circular tube 11. The outer diameter of the first tube segment 121 gradually increases from the free end towards the middle, and gradually decreases from the middle towards the end of the circular tube 11. The minimum outer diameters of the first tube segment 121 and the second tube segment 122 are equal. Specifically, when the sleeve 20 is stretched and deformed, the sleeve 20 corresponding to the first tube segment 121 changes from thick to thin, which increases the normal pressure on the contact surface at the first tube segment 121, thereby increasing the adhesive shear force at the end face. The sleeve 20 corresponding to the second tube segment 122 changes from thin to thick, and the contact surface is subjected to both normal pressure and adhesive shear force. The normal pressure increases with the increase of the deformation of the sleeve 20 at this point. In other words, when the sleeve 20 is stretched and deformed, the normal pressure of the first pipe section 121 and the second pipe section 122 will increase, and the adhesive shear force will also increase, thus producing a tightening effect and increasing the reliability of component bonding.

[0032] Furthermore, the length of the first pipe segment 121 is L1, and the length of the second pipe segment 122 is L2, with the ratio of L1 to L2 ranging from 1:2 to 3. In other words, the slope of the first pipe segment 121 changes more rapidly, resulting in a slightly smaller contact area, while the slope of the second pipe segment 122 changes more gently, resulting in a larger contact area. This makes it difficult for the sleeve 20 to detach from the second pipe segment 122, thus greatly improving the reliability of the component bonding.

[0033] To ensure the smoothness of the outer peripheral wall, the outer edges of the first pipe section 121 and the second pipe section 122 are both arc-shaped and the connection is smoothly transitioned, so as not to damage the coating layer on the sleeve 20.

[0034] The maximum outer diameter of the connecting pipe section 12 is smaller than the outer diameter of the circular pipe 11.

[0035] Even better, the outer surface of the connecting tube segment 12 is provided with a continuous thread structure, which can be a shallow thread or a knurled pattern. This increases the amount of adhesive applied and the friction between the tube and the sleeve 20, thereby ensuring the reliability of the connection between the blood flow channel 10 and the sleeve 20.

[0036] like Figure 2 As shown, the cannula 20 includes a spring body support 21 and an inner film 22 and an outer film 23 covering the inner and outer surfaces of the spring body support 21. The outer film 23 extends to the end of the spring body support 21. When in use, the cannula 20 needs to pass through blood vessels and heart valves. In order to reduce damage to the heart valves, the cannula 20 is required to be relatively soft. However, if it is made of very soft material, it will lack support and be not conducive to the percutaneous insertion of the catheter pump. When the soft cannula 20 is connected to the metal blood flow channel 10, it may be subjected to large torsional and tensile forces, which may cause it to break or the connection point to break. Therefore, the present invention uses a spring body support 21 with a certain degree of softness, and the inner and outer surfaces of the spring body support 21 are covered with films to form blood flow channels, which have a certain degree of support strength. The inner film 22 extends to a position near the end of the spring body support 21, so that at least part of the spring body support 21 is directly connected to the connecting tube section 12. In this way, the spring body support 21 is made of metal and the blood flow channel 10 is also made of metal. The connection between the two can be achieved by welding and gluing, which complement each other and together provide a reliable connection between the sleeve 20 and the blood flow channel 10.

[0037] The spring support 21 is a spiral structure made of shape memory alloy wire and is pre-shaped to conform to the physiological structure of the human body. The winding density of the shape memory alloy wire at both ends of the spring support 21 is greater than that at the middle position. In other words, the spring pitch at both ends of the spring support 21 is smaller than that at the middle position. This further improves the bending strength at the connection between the blood flow channel 10 and the sleeve 20, preventing the connection from breaking or falling off.

[0038] The shape memory alloy wire is selected from one of nickel-titanium alloy, titanium-nickel-copper alloy, titanium-nickel-iron alloy, and titanium-nickel-chromium alloy. Shape memory alloys are materials composed of two or more metallic elements that exhibit shape memory effects through thermoelasticity and martensitic phase transformation and its inverse transformation. According to the conduit pump assembly provided by the present invention, the inner film 12 and the outer film 13 can be made of the same or different plastic materials. Specifically, the inner film 22 and the outer film 23 are each independently selected from one of polyethylene, polyurethane, soft PVC, and thermoplastic elastomers.

[0039] Since both the blood inflow cage and the blood outflow cage are directly connected to the sleeve 20, the reliability of the connection must be ensured. The blood flow channel 10 is either the blood inflow cage or the blood outflow cage, and the circular tube 11 of the blood flow channel 10 has multiple flow windows 13 circumferentially opened. The blood outflow cage tends to move away from the sleeve 20 when impacted by the blood flow, and the sleeve 20 also tends to move away from the blood inflow cage when impacted by the blood flow. Therefore, strengthening the connection between them is of great importance.

[0040] Tests and trials Example 1

[0041] The component manufactured using the structure of the present invention has an outer wall of the connecting pipe section 12 that is conical with a larger diameter in the middle and smaller diameters on both sides. The connecting pipe section 12 and the sleeve 20 are connected only by an adhesive bonding process. Three sets of this structural component were tested, namely Example 1-1, Example 1-2, and Example 1-3. Example 2

[0042] The component manufactured using the structure of the present invention has a conical outer wall of the connecting pipe section 12 with a larger diameter in the middle and smaller diameters on both sides. The connecting pipe section 12 and the sleeve 20 are connected by an adhesive bonding process, and the spring body bracket 21 is partially welded to the connecting pipe section 12. Three sets of this structural component were tested, namely Example 2-1, Example 2-2, and Example 2-3.

[0043] Comparative Examples

[0044] A conventional connection mechanism is used, wherein the outer wall of the connecting pipe section 12 has a uniform diameter, and the connecting pipe section 12 and the sleeve 20 are connected only by adhesive bonding. Three sets of this structural components were tested, namely Comparative Example 1, Comparative Example 2, and Comparative Example 3.

[0045] The adhesive performance of Examples 1, 2, and the comparative examples was tested.

[0046] The test results are shown in Table 1:

[0047] Table 1

[0048] Serial Number Pull-out force (N) Assembly pass rate (%) Requirements (YY0285.1-2017) Example 1-1 45 100 ≥15 Examples 1-2 43 100 ≥15 Examples 1-3 43 100 ≥15 Example 2-1 51 100 ≥15 Example 2-2 52 100 ≥15 Example 2-3 51 100 ≥15 Comparative Example 1 14 83.5 ≥15 Comparative Example 2 18 100 ≥15 Comparative Example 3 13.5 91.3 ≥15

[0049] Adhesion performance test: The peel strength test is used to test the pull force required when the sleeve 20 is peeled from the connecting pipe section 12. The standard is YY0285.1-2017, that is, the pull force that can be withstood is ≥15N.

[0050] As shown in Table 1, the pull-out forces of the three different groups of components in Example 1 were 45N, 43N, and 43N, respectively, all of which were much greater than 15N, and the pull-out forces of the three experimental components were basically stable. In Example 2, the pull-out forces of the three different groups of components were 51N, 52N, and 51N, respectively, and the pull-out forces of the three experimental components were basically stable. However, in the comparative example, the pull-out forces of the three different groups of components were 14N, 18N, and 13.5N, respectively. Two of these groups could not meet the bonding force requirements of the components, and the pull-out forces of the three experimental components differed greatly, showing extreme instability and making it impossible to guarantee the product qualification rate.

[0051] Of course, those skilled in the art will recognize that the present invention is not limited to the details of the exemplary embodiments described above, but also includes the same or similar structures that can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0052] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A connection structure between a blood flow channel and a cannula, comprising a blood flow channel (10) and a cannula (20), wherein the blood flow channel (10) includes a circular tube (11), and a connecting tube segment (12) extends from the end of the circular tube (11) near the side of the cannula (20), characterized in that: The outer wall of the connecting pipe section (12) is a conical column with a large diameter in the middle and a small diameter on both sides. The sleeve (20) is fitted around the outer periphery of the connecting pipe section (12) and glued together. The connecting tube segment (12) includes a first tube segment (121) and a second tube segment (122) arranged sequentially from the free end of the blood flow channel (10) toward the circular tube (11). The outer diameter of the first tube segment (121) gradually increases from the free end toward the middle, and the outer diameter of the first tube segment (121) gradually decreases from the middle toward the end of the circular tube (11). The minimum outer diameters of the first tube segment (121) and the second tube segment (122) are equal. The length of the first pipe section (121) is L1, and the length of the second pipe section (122) is L2. The ratio of L1 to L2 is 1:2 to 3.

2. The connection structure between the blood flow channel and the cannula according to claim 1, characterized in that: The outer edges of the first pipe section (121) and the second pipe section (122) are both arc-shaped and the connection is smooth.

3. The connection structure between the blood flow channel and the cannula according to claim 1, characterized in that: The maximum outer diameter of the connecting pipe section (12) is smaller than the outer diameter of the circular pipe (11).

4. The connection structure between the blood flow channel and the cannula according to claim 1, characterized in that: The outer surface of the connecting pipe section (12) is provided with a continuous thread structure.

5. The connection structure between the blood flow channel and the cannula according to claim 1, characterized in that: The sleeve (20) includes a spring body support (21) and an inner film (22) and an outer film (23) covering the inner and outer sides of the spring body support (21). The outer film (23) extends to the end of the spring body support (21), and the inner film (22) extends to a position close to the end of the spring body support (21), so that at least part of the spring body support (21) is directly connected to the connecting pipe section (12).

6. The connection structure between the blood flow channel and the cannula according to claim 5, characterized in that: The spring body support (21) is a spiral structure made of shape memory alloy wire and is pre-shaped into a curved shape that is adapted to the physiological structure of the human body. The winding density of the shape memory alloy wire at both ends of the spring body support (21) is greater than that of the shape memory alloy wire in the middle position.

7. The connection structure between the blood flow channel and the cannula according to claim 6, characterized in that: The shape memory alloy wire is selected from one of nickel-titanium alloy, titanium-nickel-copper alloy, titanium-nickel-iron alloy, and titanium-nickel-chromium alloy. The inner film (22) and the outer film (23) are each independently selected from one of polyethylene, polyurethane, soft PVC and thermoplastic elastomer.

8. The connection structure between the blood flow channel and the cannula according to claim 1, characterized in that: The blood flow channel (10) is for blood to flow into or out of the cage, and the circular tube (11) of the blood flow channel (10) is provided with multiple flow windows (13) along the circumference.

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