A blood pumping catheter and ventricular assist device

Abstract

This invention discloses a blood pumping conduit and a ventricular assist device. The blood pumping conduit includes a circular conduit with a blood pumping impeller inside. Multiple flow windows are provided in the circular conduit corresponding to the blood inflow / outflow section of the impeller. Adjacent flow windows are separated by supporting connecting rods. The flow windows are rectangular or approximately rectangular in shape, with arc-shaped corners. Each flow window forms an inner edge with the inner wall of the circular conduit and an outer edge with the outer wall of the circular conduit. Both the inner and outer edges of the flow windows are chamfered. This invention utilizes a multiple flow window structure to provide a sufficiently large flow area, ensuring pumping flow rate and head; the chamfered inner and outer edges ensure blood compatibility; and the multi-point support of the supporting connecting rods increases the balance of the overall mechanical strength of the structure.

Description

Technical Field

[0001] This invention relates to the field of medical devices, and more particularly to a blood pumping catheter and a ventricular assist device. Background Technology

[0002] Percutaneous coronary intervention (PCI) is a commonly used and effective treatment for coronary artery disease. Compared with coronary artery bypass surgery, PCI has lower risks, less trauma, is less technically demanding, and allows for faster recovery. Furthermore, PCI is also suitable for the emergency treatment of acute myocardial infarction, rapidly restoring blood flow to the blocked blood vessel to restore the patient's myocardial function.

[0003] Percutaneously implantable ventricular assist devices (VADs) are miniaturized pumping devices whose pumping performance is entirely determined by the pump's operating mode and is independent of the patient's physical condition. They are active circulatory support devices, overcoming the limitations of passive circulatory support devices such as intra-aortic counterpulsation balloons (IABPs). VADs can be implanted via PCI surgery, providing more stable circulatory support during high-risk PCI procedures. This improves coronary artery and distal organ perfusion while reducing cardiac workload, contributing to intraoperative patient stability and postoperative recovery.

[0004] Short-term LVAD devices implanted via PCI require higher specifications, with the core component, the impeller, needing to be miniaturized to achieve the required pumping flow rate under high-speed operation and normal intracardiac pressure differential. In this context, in addition to innovative impeller structures, novel flow-through window structures for the pumping catheter are also needed to work in tandem to achieve the required pumping flow rate. Furthermore, improper design of the flow-through window structure can not only affect pumping flow rate but also cause severe mechanical hemolysis, which is unacceptable with artificial ventricular assist devices.

[0005] Therefore, in the technical field of LVAD products, there is a need for a catheter flow window structure with a small outer diameter of 3mm-8mm, which is feasible to manufacture and has good blood compatibility, and can be used in conjunction with a micro pump impeller to achieve the required blood flow rate for blood circulation support, while maintaining good hemolysis requirements. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a blood pumping catheter and a ventricular assist device, which solves the problems of unreasonable flow window structure and poor mechanical hemolysis performance of existing blood pumping catheters.

[0007] The technical solution adopted by the present invention to solve the above-mentioned technical problems is to provide a blood pumping conduit, including a circular conduit, in which a blood pumping impeller is disposed. The circular conduit has multiple flow windows arranged circumferentially, the flow windows being located in the blood inflow section and / or blood outflow section of the blood pumping impeller. Adjacent flow windows are separated by a supporting connecting rod. The flow windows are rectangular or approximately rectangular in shape, with arc-shaped corners. The flow windows form an inner edge with the inner wall of the circular conduit and an outer edge with the outer wall of the circular conduit. Both the inner and outer edges of the flow windows are chamfered. A dividing line is formed at the intersection of the inner and outer edges of the flow windows, dividing the wall thickness δ into δ1 and δ2. δ1 is the thickness between the dividing line and the outer wall of the circular conduit, and δ2 is the thickness between the dividing line and the inner wall of the circular conduit. k = δ1 / δ2, δ1 + δ2 = δ; where the value of k ranges from 0.8 to 3.5.

[0008] Furthermore, the chamfers of the inner and outer edges of the flow window are both elliptical angles. The elliptical trajectory of the inner edge of the flow window is the largest inner elliptical arc or a proportionally reduced version of the largest inner elliptical arc moving away from the center point of the support connecting rod, so that the elliptical trajectory is simultaneously tangent to the cross-section of the flow window and the inner wall of the circular conduit. The elliptical trajectory of the outer edge of the flow window is the largest outer elliptical arc or a proportionally reduced version of the largest outer elliptical arc moving away from the center point of the support connecting rod, so that the elliptical trajectory is simultaneously tangent to the cross-section of the flow window and the outer wall of the circular conduit.

[0009] Furthermore, the chamfers of both the inner and outer edges of the flow window are beveled, and the beveled trajectory forms four connection points. The four connection points of the beveled trajectory of the inner edge are a first connection point, a second connection point, a third connection point, and a fourth connection point. The first connection point is the intersection of the inner and outer edges; the second connection point is the midpoint where the supporting connecting rod intersects with the inner wall of the circular conduit; the third and fourth connection points are the intersections of the parallel line connecting the first and second connection points and the maximum inner elliptical arc. The third and fourth connection points are connected by a straight line; the first and third connection points are connected by an arc corresponding to the maximum inner elliptical arc or a standard arc; the second and fourth connection points are connected by an arc corresponding to the maximum inner elliptical arc. The line can be a standard arc; the four connection points of the chamfered trajectory of the outer edge are the fifth connection point, the sixth connection point, the seventh connection point, and the eighth connection point. The fifth connection point is the intersection of the inner and outer edges. The sixth connection point is the midpoint where the supporting connecting rod intersects with the outer wall of the circular guide tube. The seventh and eighth connection points are the intersections of the parallel line connecting the fifth and sixth connection points and the maximum outer elliptical arc. The line between the seventh and eighth connection points is a straight line. The line between the fifth and seventh connection points is an arc corresponding to the maximum outer elliptical arc or a standard arc. The line between the sixth and eighth connection points is an arc corresponding to the maximum outer elliptical arc or a standard arc. The radius of the standard arc is 0.005mm-0.1mm.

[0010] Furthermore, the inner edge of the flow window is chamfered, and the outer edge of the flow window is chamfered into an elliptical corner or a standard rounded corner. The chamfer trajectory of the inner edge forms four connection points: a first connection point, a second connection point, a third connection point, and a fourth connection point. The first connection point is the intersection of the inner and outer edges. The second connection point is the midpoint where the supporting connecting rod intersects with the inner wall of the circular conduit. The third and fourth connection points are the intersections of a line parallel to the line connecting the first and second connection points and the largest inner elliptical arc. The third and fourth connection points are connected by a straight line, and the first and third connection points are connected by a straight line. The arc corresponding to the maximum inner elliptical arc is either a standard arc; the arc between the second connection point and the fourth connection point is either the arc corresponding to the maximum inner elliptical arc or a standard arc; the radius of the standard arc is 0.005mm-0.1mm; when the outer edge chamfer is an elliptical angle, the elliptical trajectory of the outer edge is the maximum outer elliptical arc or is obtained by proportionally reducing the maximum outer elliptical arc and moving it away from the center point of the support connecting rod, so that the elliptical trajectory is tangent to the tangent plane of the flow window and the outer wall of the circular conduit at the same time; when the outer edge chamfer is a standard fillet, the fillet radius of the outer edge of the flow window is 0.01mm-δ1.

[0011] Furthermore, the inner edge chamfer of the flow window is an elliptical corner or a standard rounded corner, and the outer edge chamfer of the flow window is a beveled chamfer. When the inner edge chamfer is an elliptical corner, the elliptical trajectory of the inner edge is the maximum inner elliptical arc or a proportionally reduced maximum inner elliptical arc moving away from the center point of the support connecting rod, so that the elliptical trajectory is tangent to both the tangent plane of the flow window and the inner wall of the circular conduit. When the inner edge chamfer is a standard rounded corner, the radius of the rounded corner of the inner edge of the flow window is 0.01mm-δ2. The beveled chamfer trajectory of the outer edge forms four connection points, namely the fifth connection point, the sixth connection point, and the seventh connection point. The fifth connection point is the intersection of the inner and outer edges; the sixth connection point is the midpoint where the supporting connecting rod intersects with the outer wall of the circular guide tube; the seventh and eighth connection points are the intersections of the parallel line connecting the fifth and sixth connection points and the maximum outer elliptical arc; the line between the seventh and eighth connection points is a straight line; the line between the fifth and seventh connection points is an arc corresponding to the maximum outer elliptical arc or a standard arc; the line between the sixth and eighth connection points is an arc corresponding to the maximum outer elliptical arc or a standard arc; the radius of the standard arc ranges from 0.005mm to 0.1mm.

[0012] Furthermore, the chamfers of the inner and outer edges of the flow window are both standard rounded corners, with the standard rounded corner radius of the inner edge of the flow window being 0.01mm-δ2 and the standard rounded corner radius of the outer edge of the flow window being 0.01mm-δ1.

[0013] Furthermore, the number of flow windows is determined by the ratio of the pump impeller radius to the outer radius of the circular catheter, and the formula for calculating the number of flow windows n is as follows:

[0014] n≥180° / arc cos(r / R);

[0015] Where r is the radius of the blood pump impeller, R is the outer radius of the circular catheter, and n is an integer value greater than or equal to the calculation result.

[0016] Furthermore, the outer diameter D of the circular conduit is 3mm-8mm, the wall thickness δ of the circular conduit is 0.1mm-0.5mm, and the wall thickness δ of the circular conduit is directly proportional to the outer diameter D.

[0017] Furthermore, the angle θ1 of the center angle of the supporting connecting rod corresponding to the axis of the circular conduit is 10°-20°.

[0018] Furthermore, the central angle θ2 corresponding to the axis of the circular conduit of the flow window is less than θ0, and the formulas for calculating θ2 and θ0 are as follows:

[0019] θ2 = 360° / n - θ1;

[0020] Where n is the number of flow windows, and θ1 is the central angle of the circular duct axis corresponding to the support connecting rod;

[0021] θ2 < θ0 = arccos(r / R);

[0022] Where r is the radius of the pump impeller and R is the outer radius of the circular catheter.

[0023] Furthermore, the formulas for calculating the width b and height h of the flow window are as follows:

[0024]

[0025] Where θ2 is the central angle of the circular conduit axis corresponding to the flow window, and D is the outer diameter of the circular conduit;

[0026]

[0027] Where vm is the axial velocity of the pump impeller at the far end of the flow window, v0 is the radial velocity at the hub of the pump impeller, r0 is the radius at the hub of the pump impeller, and R1 is the inner radius of the circular catheter.

[0028] Furthermore, the radius of the arc of the flow window at the corner is 0.3mm-1.5mm.

[0029] Another technical solution adopted by the present invention to solve the above-mentioned technical problems is to provide a ventricular assist device, including the above-mentioned blood pumping catheter.

[0030] Compared with existing technologies, the present invention has the following advantages: The blood pumping catheter provided by the present invention employs a multiple flow-through window structure to provide a sufficiently large flow-through area, ensuring blood pumping flow rate and head; the chamfered inner and outer edges ensure blood compatibility; and the multi-point support of the supporting connecting rod increases the balance of the mechanical strength of the entire structure. When assembled with a miniature blood pumping impeller, it can provide higher blood pumping efficiency than traditional flow-through window structures under the same rotational speed and operating conditions. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of a circular conduit provided by the present invention;

[0032] Figure 2 This is a front view of the circular catheter provided by the present invention;

[0033] Figure 3 A cross-sectional view of the circular conduit provided by the present invention;

[0034] Figure 4 A cross-sectional view of the flow window of the circular conduit provided by the present invention;

[0035] Figure 5 This is a schematic diagram of the maximum inner elliptical arc and the maximum outer elliptical arc provided by the present invention;

[0036] Figure 6 A cross-sectional view showing that both the inner and outer edges of the device have elliptical chamfers, as provided in this invention.

[0037] Figure 7 A cross-sectional view provided for this invention, showing that both the inner and outer edges are beveled.

[0038] Figure 8 A cross-sectional view provided by the present invention, wherein the inner edge chamfer is a beveled chamfer and the outer edge chamfer is an elliptical angle;

[0039] Figure 9 A cross-sectional view provided by the present invention, showing that the inner edge chamfer is an elliptical angle and the outer edge chamfer is an oblique angle;

[0040] Figure 10 A cross-sectional view provided for this invention, showing that both the inner and outer edges have standard rounded corners;

[0041] Figure 11 This is a schematic diagram of a ventricular assist device.

[0042] In the picture:

[0043] 1. Circular conduit; 2. Flow window; 2-1. Rounded chamfer; 2-2. Inner edge; 2-3. Outer edge; 2-4. Support connecting rod; 4. Maximum inner elliptical arc; 5. Maximum outer elliptical arc; 11. First connection point; 12. Second connection point; 13. Third connection point; 14. Fourth connection point; 15. Fifth connection point; 16. Sixth connection point; 17. Seventh connection point; 18. Eighth connection point. Detailed Implementation

[0044] The invention will now be further described with reference to the accompanying drawings and the accompanying text.

[0045] Figure 1 This is a schematic diagram of the blood pumping catheter and ventricular assist device provided by the present invention; Figure 2 This is a front view of the blood pumping catheter and ventricular assist device provided by the present invention; Figure 3 A cross-sectional view of the circular conduit provided by the present invention; Figure 4 A cross-sectional view of the flow window of the circular conduit provided by the present invention.

[0046] Please see Figures 1-4The blood pumping conduit provided by this invention includes a circular conduit 1, in which a blood pumping impeller is disposed. The circular conduit 1 has multiple flow windows 2 arranged circumferentially, located in the blood inflow section and / or blood outflow section of the blood pumping impeller. Adjacent flow windows 2 are separated by supporting connecting rods 2-4. The flow windows 2 are rectangular or approximately rectangular in shape, and a rounded chamfer 2-1 is formed at the corners of the flow windows 2. The flow windows 2 form an inner edge 2- with the inner wall of the circular conduit 1. 2. The flow window 2 forms an outer edge 2-3 with the outer wall of the circular conduit 1. Both the inner edge 2-2 and the outer edge 2-3 of the flow window 2 are chamfered. A dividing line is formed at the intersection of the inner and outer edges of the flow window, dividing the wall thickness δ into δ1 and δ2. δ1 is the thickness between the dividing line and the outer wall of the circular conduit, and δ2 is the thickness between the dividing line and the inner wall of the circular conduit. k = δ1 / δ2, δ1 + δ2 = δ; where the value of k ranges from 0.8 to 3.5. When the value of k is less than 0.8 or greater than 3.5, the average maximum shear stress of the impeller during periodic rotation through the window will increase sharply, resulting in poor blood compatibility. As the wall thickness δ increases, the value of k gradually increases, and δ1 and δ2 also gradually increase.

[0047] Specifically, the number of flow windows 2 is determined by the ratio of the pump impeller radius to the outer radius of the circular catheter 1. The formula for calculating the number n of flow windows 2 is as follows:

[0048] n≥180° / arc cos(r / R);

[0049] Where r is the radius of the pump impeller, R is the outer radius of the circular catheter 1, and n is an integer value greater than or equal to the calculated result. The number of flow windows 2, n, is between 5 and 8. If the value of n is too small, the number of windows is small, which may cause the overall structure to scratch the blood vessel wall and aortic valve during the process of entering the blood vessels and heart. If the value of n is too large, the number of windows is large, which may cause the flow rate of the circular catheter 1 to be small during operation and the hemolysis value to increase.

[0050] Specifically, the outer diameter D of the circular catheter 1 is 3mm-8mm, and the wall thickness δ of the circular catheter 1 is 0.1mm-0.5mm. The wall thickness δ of the circular catheter 1 is directly proportional to the outer diameter D. The angle θ1 of the support connecting rod 2-4 corresponding to the central angle of the axis of the circular catheter 1 is within 10°-20°. If the value of θ1 is too small, the support connecting rod 2-4 is prone to insufficient strength and easy damage to the component. If the value of θ1 is too large, the flow window 2 is prone to being too small, resulting in a small flow rate and an increased hemolysis value.

[0051] Specifically, the central angle θ2 of the axis of the circular duct 1 corresponding to the flow window 2 is less than θ0. The formulas for calculating θ2 and θ0 are as follows:

[0052] θ2 = 360° / -θ1;

[0053] Where n is the number of flow windows 2, and θ1 is the central angle of the axis of the circular conduit 1 corresponding to the support connecting rods 2-4;

[0054] θ2 < θ0 = arccos(r / R);

[0055] Where r is the radius of the blood pump impeller and R is the outer radius of the circular catheter 1.

[0056] Specifically, the formulas for calculating the width b and height h of the flow window 2 are as follows:

[0057]

[0058] Where θ2 is the central angle of the axis of the circular conduit 1 corresponding to the flow window 2, and D is the outer diameter of the circular conduit 1;

[0059]

[0060] Where vm is the axial velocity of the pump impeller at the far end of the flow window 2, v0 is the radial velocity at the hub of the pump impeller, r0 is the radius at the hub of the pump impeller, and R1 is the inner radius of the circular conduit 1.

[0061] Specifically, the radius of the chamfer 2-1 at the corner of the flow window 2 is 0.3mm-1.5mm.

[0062] Please also see Figure 5 The blood pumping catheter provided by this invention has a maximum inner elliptical arc 4 on the inner edge 2-2 of the flow window 2. The maximum inner elliptical arc 4 is an elliptical arc determined by three points: the intersection of the inner edge 2-2 and the outer edge 2-3 of the flow window 2, the intersection of the inner edge 2-2 and the outer edge 2-3 of adjacent flow windows 2, and the midpoint of the intersection of the supporting connecting rod 2-4 where the flow window 2 is located and the inner wall of the circular catheter 1. The outer edge 2-3 of the flow window 2 has a maximum outer elliptical arc 5. The maximum outer elliptical arc 5 is an elliptical arc determined by three points: the intersection of the inner edge 2-2 and the outer edge 2-3 of the flow window 2, the intersection of the inner edge 2-2 and the outer edge 2-3 of adjacent flow windows 2, and the midpoint of the intersection of the supporting connecting rod 2-4 where the flow window 2 is located and the outer wall of the circular catheter 1.

[0063] Specifically, the major and minor axis lengths and their positions of the major and minor axes of the largest inner elliptical arc 4 and the largest outer elliptical arc 5 are determined by the intersection point of the inner edge 2-2 and the outer edge 2-3 of the flow window 2 determined according to the k value, the intersection point of the inner edge 2-2 and the outer edge 2-3 of the flow window 2 adjacent to the support connecting rod 2-4 determined according to the k value, and the midpoint of the intersection of the support connecting rod 2-4 with the inner and outer walls of the circular conduit 1. The line connecting the intersection of the inner edge 2-2 and the outer edge 2-3 of the flow window 2 and the intersection of the inner edge 2-2 and the outer edge 2-3 of the flow window 2 adjacent to the support connecting rod 2-4 is the major axis of the maximum inner elliptical arc 4, and also the major axis of the maximum outer elliptical arc 5; the perpendicular distance from the midpoint of the intersection of the support connecting rod 2-4 and the outer wall of the circular conduit 1 to the major axis of the maximum outer elliptical arc 5 is the minor axis of the maximum outer elliptical arc 5; the perpendicular distance from the midpoint of the intersection of the support connecting rod 2-4 and the inner wall of the circular conduit 1 to the major axis of the maximum inner elliptical arc 4 is the minor axis of the maximum inner elliptical arc 4.

[0064] Please also see Figure 6 The blood pumping catheter provided by this invention has elliptical angles at the inner edge 2-2 and outer edge 2-3 of the flow window 2. The elliptical trajectory of the inner edge 2-2 of the flow window 2 is the maximum inner elliptical arc 4 or is a proportionally reduced version of the maximum inner elliptical arc 4 and moves away from the center point of the support connecting rod 2-4, so that the elliptical trajectory is simultaneously tangent to the cross-section of the flow window 2 and the inner wall of the circular catheter 1. The elliptical trajectory of the outer edge 2-3 of the flow window 2 is the maximum outer elliptical arc 5 or is a proportionally reduced version of the maximum outer elliptical arc 5 and moves away from the center point of the support connecting rod 2-4, so that the elliptical trajectory is simultaneously tangent to the cross-section of the flow window 2 and the outer wall of the circular catheter 1.

[0065] The elliptical trajectory is difficult to process. To reduce the processing difficulty while ensuring hemolytic performance, some straight-line cutting is used instead of arc cutting to form a chamfered trajectory that is close to the elliptical trajectory.

[0066] Please also see Figure 7The blood pumping catheter provided by this invention has beveled edges on both the inner edge 2-2 and the outer edge 2-3 of the flow window 2, with each beveled edge forming four connection points. The four connection points of the beveled edge trajectory of the inner edge 2-2 of the flow window 2 are designated as first connection point 11, second connection point 12, third connection point 13, and fourth connection point 14. First connection point 11 is the intersection of the inner edge 2-2 and the outer edge 2-3; second connection point 12 is the midpoint where the supporting connecting rod 2-4 intersects the inner wall of the circular catheter 1; third connection point 13 and fourth connection point 14 are the intersections of the parallel line connecting first connection point 11 and second connection point 13 and the maximum inner elliptical arc 4. The line between third connection point 13 and fourth connection point 14 is straight; the line between first connection point 11 and third connection point 13 is an arc corresponding to the maximum inner elliptical arc 4; and the line between second connection point 12 and fourth connection point 14 is an arc corresponding to the maximum inner elliptical arc 4.

[0067] The four connection points of the chamfered trajectory of the outer edge 2-3 of the flow window 2 are the fifth connection point 15, the sixth connection point 16, the seventh connection point 17, and the eighth connection point 18. The fifth connection point 15 is the intersection of the inner edge 2-2 and the outer edge 2-3. The sixth connection point 16 is the midpoint of the intersection of the supporting connecting rod 2-4 and the outer wall of the circular conduit 1. The seventh connection point 17 and the eighth connection point 18 are the intersection of the parallel line connecting the fifth connection point 15 and the sixth connection point 16 with the maximum outer elliptical arc 5. The line between the seventh connection point 17 and the eighth connection point 18 is a straight line. The line between the fifth connection point 15 and the seventh connection point 17 is an arc corresponding to the maximum outer elliptical arc 5. The line between the sixth connection point 16 and the eighth connection point 18 is an arc corresponding to the maximum outer elliptical arc 5.

[0068] Specifically, in order to further reduce the processing difficulty, the first connection point 11 and the third connection point 13 can be a standard arc; the second connection point 12 and the fourth connection point 14 can be a standard arc; the fifth connection point 15 and the seventh connection point 17 can be a standard arc; the sixth connection point 16 and the eighth connection point 18 can be a standard arc; the radius of the standard arc is 0.005mm-0.1mm.

[0069] Please also see Figure 8The blood pumping catheter provided by this invention has an inner edge 2-2 of the flow window 2 with a chamfered angle, and an outer edge 2-3 of the flow window 2 with an elliptical angle. The chamfered trajectory of the inner edge 2-2 forms four connection points: a first connection point 11, a second connection point 12, a third connection point 13, and a fourth connection point 14. The first connection point 11 is the intersection of the inner edge 2-2 and the outer edge 2-3. The second connection point 12 is the midpoint where the supporting connecting rod 2-4 intersects with the inner wall of the circular catheter 1. The third connection point 13 and the fourth connection point 14 are the intersections of the parallel line connecting the first connection point 11 and the second connection point 12 and the maximum inner elliptical arc 4. The connection between connection point 13 and the fourth connection point 14 is a straight line; the connection between the first connection point 11 and the third connection point 13 is an arc corresponding to the maximum inner elliptical arc 4 or a standard arc; the connection between the second connection point 12 and the fourth connection point 14 is an arc corresponding to the maximum inner elliptical arc 4 or a standard arc; the elliptical trajectory of the outer edge 2-3 is the maximum outer elliptical arc 5 or is obtained by proportionally reducing the maximum outer elliptical arc 5 and moving it away from the center point of the support connecting rod 2-4, so that the elliptical trajectory is tangent to the tangent plane of the flow window 2 and the outer wall of the circular conduit 1 at the same time; the radius of the standard arc is 0.005mm-0.1mm.

[0070] Specifically, in order to reduce the processing difficulty, the chamfer of the outer edge 2-3 can be a standard fillet, and the standard fillet radius of the outer edge 2-3 of the flow window 2 is 0.01mm-δ1.

[0071] Please also see Figure 9 The blood pumping catheter provided by this invention has an elliptical chamfer on the inner edge 2-2 of the flow window 2 and an oblique chamfer on the outer edge 2-3 of the flow window 2. The elliptical trajectory of the inner edge 2-2 is the largest inner elliptical arc 4 or a proportionally reduced version of the largest inner elliptical arc 4, moving away from the center point of the supporting connecting rod 2-4, so that the elliptical trajectory is tangent to both the tangent plane of the flow window 2 and the inner wall of the circular catheter 1. The oblique chamfer trajectory of the outer edge 2-3 forms four connection points: the fifth connection point 15, the sixth connection point 16, the seventh connection point 17, and the eighth connection point 18. The fifth connection point 15 is the connection point between the inner edge 2-2 and the outer edge 2-3. 3. The sixth connection point 16 is the midpoint where the supporting connecting rod 2-4 intersects with the outer wall of the circular conduit 1. The seventh connection point 17 and the eighth connection point 18 are the intersections of the parallel line connecting the fifth connection point 15 and the sixth connection point 16 with the maximum outer elliptical arc 5. The line between the seventh connection point 17 and the eighth connection point 18 is a straight line. The line between the fifth connection point 15 and the seventh connection point 17 is an arc corresponding to the maximum outer elliptical arc 5 or a standard arc. The line between the sixth connection point 16 and the eighth connection point 18 is an arc corresponding to the maximum outer elliptical arc 5 or a standard arc. The radius of the standard arc is 0.005mm-0.1mm.

[0072] Specifically, in order to reduce the processing difficulty, the chamfer of the inner edge 2-2 can be a standard rounded corner, and the standard rounded corner radius of the inner edge 2-2 is 0.01mm-δ2.

[0073] Please also see Figure 10 The blood pumping catheter provided by this invention has standard rounded corners on both the inner edge 2-2 and the outer edge 2-3 of the flow window. The standard rounded corner radius of the inner edge of the flow window is 0.01mm-δ2, and the standard rounded corner radius of the outer edge of the flow window is 0.01mm-δ1. Standard rounded corners reduce the processing difficulty compared to elliptical corners.

[0074] The blood pumping catheter provided by this invention measures the maximum shear stress under various conditions through fluid simulation experiments. This includes measuring the maximum shear stress under different k values ​​but with the same chamfering method on the inner edge 2-2 and outer edge 2-3 of the flow window 2; measuring the maximum shear stress under different chamfering methods but with the same k value; and measuring the maximum shear stress under conditions where the inner edge 2-2 and outer edge 2-3 are not chamfered. The comparison results are shown in Table 1 below:

[0075] Table 1: Maximum Shear Stress

[0076]

[0077] State 1: The chamfers of both inner edge 2-2 and outer edge 2-3 are elliptical angles: take k = 2.5. The data in the table represent the maximum shear stress at different locations, with an average maximum shear stress of 470 Pa.

[0078] State 2: The chamfers of both inner edge 2-2 and outer edge 2-3 are elliptical angles: take k = 0.8. The data in the table represent the maximum shear stress at different locations, with an average maximum shear stress of 552.5 Pa.

[0079] State 3: The chamfers of both inner edge 2-2 and outer edge 2-3 are elliptical angles: take k = 3.5. The data in the table represent the maximum shear stress at different locations, with an average maximum shear stress of 545 Pa.

[0080] State 4: The chamfers of both inner edge 2-2 and outer edge 2-3 adopt standard fillets: take k = 2.5, the data in the table represent the maximum shear stress at different locations, and the average maximum shear stress is 573 Pa;

[0081] State 5: The chamfers of both inner edge 2-2 and outer edge 2-3 are beveled: take k = 2.5. The data in the table represent the maximum shear stress at different locations, with an average maximum shear stress of 559 Pa.

[0082] State 6: The chamfer of the inner edge 2-2 is a beveled chamfer, and the chamfer of the outer edge 2-3 is an elliptical chamfer: take k = 2.5. The data in the table represent the maximum shear stress at different locations, and the average maximum shear stress is 558 Pa.

[0083] State 7: The chamfer of the inner edge 2-2 is an elliptical chamfer, and the chamfer of the outer edge 2-3 is a beveled chamfer: take k = 2.5. The data in the table represent the maximum shear stress at different locations, and the average maximum shear stress is 486 Pa.

[0084] State 8: Inner edge 2-2 and outer edge 2-3 are not chamfered. The data in the table represent the maximum shear stress at different locations, with an average maximum shear stress of 684.5 Pa.

[0085] The comparison above shows that the best effect is achieved when both inner edge 2-2 and outer edge 2-3 have elliptical chamfers with a k value of 2.5. The next best effect is achieved when the outer edge 2-3 has a beveled chamfer and the inner edge 2-2 has an elliptical chamfer. Then, for other k values, both inner edge 2-2 and outer edge 2-3 have elliptical chamfers. Next, when the k value is 2.5, both inner edge 2-2 and outer edge 2-3 have standard rounded corners. Then, when the k value is 2.5, both inner edge 2-2 and outer edge 2-3 have beveled chamfers, and the combination of the inner edge 2-2 beveled chamfer and the outer edge 2-3 elliptical chamfer is also an option. The worst result is the rectangular scheme without any chamfering. Therefore, it is evident that the value of k and the chamfering method greatly contribute to improving hemolytic performance.

[0086] Please see Figure 11 The ventricular assist device provided by the present invention has a circular catheter 1 with a flow window 2 located in the blood inflow section and the blood outflow section of the pump impeller.

[0087] In summary, the blood pumping conduit and ventricular assist device provided by this invention, in conjunction with the blood pumping impeller, perform work on the blood. The multiple flow windows 2 structure provide a sufficiently large flow area to ensure pumping flow rate and head. The chamfered inner edge 2-2 and outer edge 2-3 ensure blood compatibility. The multi-point support of the supporting connecting rod 2-4 increases the balance of the overall mechanical strength. When assembled with a miniature blood pumping impeller, it provides higher pumping efficiency than traditional outflow structures under the same rotational speed and operating conditions.

[0088] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any person skilled in the art may make some modifications and improvements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be defined by the claims.

Claims

1. A blood pump catheter, characterized by, The application relates to a blood pump, which comprises a circular conduit provided with a blood pumping impeller, a plurality of flow windows are arranged on the circular conduit in a circumferential direction, the flow windows are located at blood inflow sections and / or blood outflow sections of the blood pumping impeller, two adjacent flow windows are separated by a supporting connecting rod, the flow windows are in a rectangular or approximately rectangular shape, and corners of the flow windows are in an arc shape; inner edges of the flow windows and outer edges of the flow windows are formed by inner walls and outer walls of the circular conduit; and chamfers are formed on the inner edges and the outer edges of the flow windows. The inner edges and the outer edges of the flow windows intersect to form a separation line, the separation line divides a pipe wall thickness delta into delta 1 and delta 2, delta 1 is a thickness between the separation line and the outer wall of the circular conduit, delta 2 is a thickness between the separation line and the inner wall of the circular conduit, k=delta 1 / delta 2, delta 1+delta 2=delta, and the value of k ranges from 0.8 to 3.

5. The height h of the flow window is calculated according to the following formula: h=vm*v0 / (r0*R1), wherein vm is an axial speed of a distal end of the flow window, v0 is a radial speed at a hub of the blood pumping impeller, r0 is a radius at the hub of the blood pumping impeller, and R1 is an inner radius of the circular conduit. ； The chamfers on the inner edges and the outer edges of the flow windows are all elliptical chamfers, the elliptical track of the inner edge of the flow window is a maximum inner elliptical arc or is obtained by proportionally reducing the maximum inner elliptical arc and moving the maximum inner elliptical arc in a direction away from a center point of the supporting connecting rod, so that the elliptical track is tangent to a flow window section and an inner wall of the circular conduit; and the elliptical track of the outer edge of the flow window is a maximum outer elliptical arc or is obtained by proportionally reducing the maximum outer elliptical arc and moving the maximum outer elliptical arc in a direction away from the center point of the supporting connecting rod, so that the elliptical track is tangent to the flow window section and an outer wall of the circular conduit.

2. The blood pump catheter of claim 1, wherein, The chamfers on the inner edges and the outer edges of the flow windows are all bevel chamfers, and the bevel chamfer track forms four connecting points; the four connecting points of the bevel chamfer track of the inner edge are a first connecting point, a second connecting point, a third connecting point and a fourth connecting point, the first connecting point is an intersection point of the inner edge and the outer edge, the second connecting point is a midpoint where the supporting connecting rod and the inner wall of the circular conduit intersect, the third connecting point and the fourth connecting point are intersection points of a parallel line of a line connecting the first connecting point and the second connecting point and the maximum inner elliptical arc; a straight line is formed between the third connecting point and the fourth connecting point, an arc corresponding to the maximum inner elliptical arc or a standard circular arc is formed between the first connecting point and the third connecting point; and an arc corresponding to the maximum inner elliptical arc or a standard circular arc is formed between the second connecting point and the fourth connecting point.

3. The blood pump catheter of claim 1, wherein, ​ The four connection points of the bevel chamfer track of the outer edge are respectively a fifth connection point, a sixth connection point, a seventh connection point and an eighth connection point, the fifth connection point is an intersection point of the inner edge and the outer edge, the sixth connection point is a midpoint of the intersection of the support connecting rod and the outer wall of the circular conduit, the seventh connection point and the eighth connection point are intersection points of the parallel line of the connecting line of the fifth connection point and the sixth connection point and the maximum outer elliptical arc; the seventh connection point and the eighth connection point are straight lines, the fifth connection point and the seventh connection point are an arc corresponding to the maximum outer elliptical arc or a standard circular arc; the sixth connection point and the eighth connection point are an arc corresponding to the maximum outer elliptical arc or a standard circular arc; the radius of the standard circular arc ranges from 0.005mm to 0.1mm.

4. The blood pump catheter of claim 1, wherein, The inner edge chamfer of the flow window is a bevel chamfer, and the outer edge chamfer of the flow window is an elliptical chamfer or a standard circular chamfer; The four connection points of the bevel chamfer track of the outer edge are respectively a fifth connection point, a sixth connection point, a seventh connection point and an eighth connection point, the fifth connection point is an intersection point of the inner edge and the outer edge, the sixth connection point is a midpoint of the intersection of the support connecting rod and the outer wall of the circular conduit, the seventh connection point and the eighth connection point are intersection points of the parallel line of the connecting line of the fifth connection point and the sixth connection point and the maximum outer elliptical arc; the seventh connection point and the eighth connection point are straight lines, the fifth connection point and the seventh connection point are an arc corresponding to the maximum outer elliptical arc or a standard circular arc; the sixth connection point and the eighth connection point are an arc corresponding to the maximum outer elliptical arc or a standard circular arc; the radius of the standard circular arc ranges from 0.005mm to 0.1mm. When the outer edge chamfer is an elliptical chamfer, the elliptical track of the outer edge is a maximum outer elliptical arc or is reduced in scale from the maximum outer elliptical arc and moves in a direction away from the center point of the support connecting rod, so that the elliptical track is tangent to the flow window section and the outer wall of the circular conduit at the same time; When the outer edge chamfer is a standard circular chamfer, the radius of the circular chamfer of the outer edge of the flow window is 0.01mm-δ1.

5. The blood pump catheter of claim 1, wherein, The inner edge chamfer of the flow window is an elliptical chamfer or a standard circular chamfer, and the outer edge chamfer of the flow window is a bevel chamfer, When the inner edge chamfer is an elliptical chamfer, the elliptical track of the inner edge is a maximum inner elliptical arc or is reduced in scale from the maximum inner elliptical arc and moves in a direction away from the center point of the support connecting rod, so that the elliptical track is tangent to the flow window section and the inner wall of the circular conduit at the same time; When the inner edge chamfer is a standard circular chamfer, the radius of the circular chamfer of the inner edge of the flow window is 0.01mm-δ2; The bevelled corner track of the outer edge forms four connection points, which are the fifth connection point, the sixth connection point, the seventh connection point and the eighth connection point, respectively. The fifth connection point is the intersection point of the inner edge and the outer edge. The sixth connection point is the midpoint of the intersection of the support connecting rod and the outer wall of the circular conduit. The seventh connection point and the eighth connection point are the intersection points of the parallel line of the connecting line of the fifth connection point and the sixth connection point and the largest outer ellipse arc. The seventh connection point and the eighth connection point are in a straight line. The fifth connection point and the seventh connection point are in an arc corresponding to the largest outer ellipse arc or a standard arc. The sixth connection point and the eighth connection point are in an arc corresponding to the largest outer ellipse arc or a standard arc. The radius of the standard arc ranges from 0.005 mm to 0.1 mm.

6. The blood pump catheter of claim 1, wherein, The bevelled corners of the inner edge and the outer edge of the flow window are standard round corners. The radius of the standard round corner of the inner edge of the flow window is 0.01 mm-δ2. The radius of the standard round corner of the outer edge of the flow window is 0.01 mm-δ1.

7. The blood pump catheter of claim 1, wherein, The number of the flow windows is determined by the ratio of the radius of the blood-pumping impeller to the outer radius of the circular conduit. The number n of the flow windows is calculated according to the following formula: ； wherein r is the radius of the blood-pumping impeller, R is the outer radius of the circular conduit, and n is an integer greater than or equal to the calculated result.

8. The blood pump catheter of claim 1, wherein, The outer diameter D of the circular conduit ranges from 3 mm to 8 mm. The wall thickness δ of the circular conduit ranges from 0.1 mm to 0.5 mm. The wall thickness δ of the circular conduit is directly proportional to the outer diameter D.

9. The blood pump catheter of claim 1, wherein, The central angle θ1 of the support connecting rod corresponding to the axis of the circular conduit ranges from 10° to 20°. The central angle θ2 of the flow window corresponding to the axis of the circular conduit is less than θ0. θ2 and θ0 are calculated according to the following formula: ； wherein n is the number of the flow windows, and θ1 is the central angle of the support connecting rod corresponding to the axis of the circular conduit. ； wherein r is the radius of the blood-pumping impeller, and R is the outer radius of the circular conduit.

10. The blood pump catheter of claim 1, wherein, The width b of the flow window is calculated according to the following formula: ； wherein θ2 is the central angle of the flow window corresponding to the axis of the circular conduit, and D is the outer diameter of the circular conduit.

11. The blood pump catheter of claim 1, wherein, The arc radius of the flow window at the corner ranges from 0.3 mm to 1.5 mm.

12. A ventricular assist device, characterized by The blood-pumping conduit comprises the blood-pumping conduit according to any one of claims 1-11.

Images