Interventional foldable left ventricle auxiliary device

Abstract

The invention relates to an intrusive foldable left ventricle auxiliary device, the near end of a driving shaft is connected with a motor, the far end of the driving shaft is connected with a pump head assembly, and the pump head assembly comprises a foldable impeller driven by the driving shaft and an expandable support covering the periphery of the foldable impeller; the expandable stent is covered with a blood flow flexible film, a blood inlet is formed in the far end of the blood flow flexible film, and at least one blood outlet is formed in the near end area of the blood flow flexible film; the blood flow flexible membrane comprises a first channel, an expansion section and a second channel. When blood passes through the expansion section, the blood flow speed is reduced, the flow distribution is uniform, and the shearing force borne by the blood is directly reduced, so that the hemolysis risk is remarkably reduced from the source; meanwhile, blood flow is more stable, turbulent flow and flow stagnation areas are reduced, and the thrombosis risk is reduced; the near-end edge of the expansion section is located on the far side of the near-end edge of the expandable stent, after blood is decelerated, damage caused by impacting the inner wall of the stent is reduced, and hemolysis is further reduced.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, specifically to an interventional foldable left ventricular assist device. Background Technology

[0002] The interventional foldable left ventricular assist device (LVAP) is a ventricular assist device that provides short-term cardiac support to patients. In use, the pump head assembly of the interventional foldable LVAP spans the aortic valve in its folded state. Once it reaches the designated position, the constraint is released, and the foldable stent and foldable impeller are located in the left ventricle and expand. The bleeding point of the blood flow flexible membrane is located in the ascending aorta. The power from the external motor is transmitted to the impeller inside the body via a flexible drive shaft, pumping blood from the left ventricle to the aorta, thus assisting or replacing the heart's pumping function. As the core component of the interventional foldable LVAP, the structure, shape, and fit of the foldable stent, foldable impeller, and blood flow flexible membrane directly affect the hydraulic and hemolytic performance of the blood pump, and therefore have always been a key research focus in the industry. As a foldable device, merely meeting the requirements for hydraulic and hemolytic performance is far from sufficient; the folding and repositioning capabilities of the foldable stent and foldable impeller are also crucial. Summary of the Invention

[0003] The purpose of this invention is to provide an interventional foldable left ventricular assist device that is easy to fold and has good hydraulic and hemolytic properties.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: an interventional foldable left ventricular assist device, comprising a drive shaft, the proximal end of which is connected to a motor and the distal end of which is connected to a pump head assembly. The pump head assembly includes a foldable impeller driven by the drive shaft and an expandable support covering the outer periphery of the foldable impeller. The expandable support is covered with a blood flow flexible membrane, the distal end of which forms a blood inlet, and at least one bleeding outlet is provided in the proximal region. Furthermore, the blood flow flexible membrane includes: The first channel is installed on the cylindrical section of the expandable support; An expansion section connected to the proximal end of the first channel has a diameter that gradually increases from distal to proximal, and its proximal edge is located distal to the proximal edge of the expandable stent. And a second channel connected to the proximal end of the expansion section, the main body of the second channel having the same diameter as the maximum diameter of the expansion section, the proximal end of the second channel being fixed to a conduit sleeved outside the drive shaft, and the bleeding outlet being opened on the side wall adjacent to the proximal end of the second channel.

[0005] Furthermore, the length of the expansion section is 2 to 5 mm, and the angle α between its generatrix and the axis of the device is 3 to 9°.

[0006] Furthermore, there are two bleeding openings, and when viewed from the far end to the near end of the device, the two bleeding openings have a right-handed spiral structure.

[0007] Furthermore, the expansion support includes a cylindrical segment and distal conical segments and proximal conical segments at both ends; wherein, the distal conical segments and proximal conical segments are asymmetrical structures, and the angle between the axis of the proximal conical segment and the axis of the cylindrical segment is smaller than the angle between the axis of the distal conical segment and the axis of the cylindrical segment.

[0008] Furthermore, the first channel is formed by bonding and fixing an inner membrane and an outer membrane placed on the inner and outer surfaces of the cylindrical segment through a hot-melt process; the distal and proximal edges of the inner membrane are flush with the distal and proximal edges of the cylindrical segment, respectively, and the outer membrane extends from the proximal edge of the cylindrical segment to the proximal end, thereby forming an expansion segment and a second channel in sequence.

[0009] Furthermore, the distal conical section and the proximal conical section each have eight legs, and the width of each leg gradually narrows from its tip toward the cylindrical section; each leg is provided with a foot at its end, and the foot and the corresponding groove on the proximal or distal shell form an inverted snap-fit ​​structure; the outer wall of the mating section of the groove and the foot is fitted with a shell steel ring and fixed with adhesive.

[0010] Furthermore, the foldable impeller is injection molded from TPU material and includes a hub and multiple blades disposed on the surface of the hub. The root portion of the blades is perpendicular to the surface of the hub, and the blades located on the impeller inlet side have a twisting direction opposite to the rotation direction of the foldable impeller.

[0011] Furthermore, the distal edge of the blade is located near the distal edge of the cylindrical section, and the axial distance L between the two is 1.5 to 2.5 mm. The thickness of the blade gradually decreases from the inlet end to the outlet end, and its thickness ranges from 0.25 to 0.35 mm.

[0012] Furthermore, when the device is in its expanded and deployed state, the gap between the blade tip and the inner wall of the inner membrane is less than 0.3 mm.

[0013] Furthermore, the drive shaft includes a flexible shaft at the proximal end and a rigid shaft at the distal end. The foldable impeller is fixedly installed on the rigid shaft, and the proximal end of the rigid shaft and the proximal end housing form a support rotational fit, while the distal end of the rigid shaft and the distal end housing form an axial sliding and circumferential rotational fit.

[0014] In the above scheme, when blood passes through the expansion section, the blood flow velocity decreases and the flow distribution becomes more uniform, directly reducing the shear force on the blood and thus significantly reducing the risk of hemolysis from the root cause. At the same time, the blood flow is more stable, reducing turbulence and flow stagnation areas, and reducing the risk of thrombosis. The proximal edge of the expansion section is located distal to the proximal edge of the expandable stent. After the blood is decelerated, the damage caused by impacting the inner wall of the stent is reduced, further reducing hemolysis. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall structure of the device; Figure 2 This is a schematic diagram of the pump head assembly. Figure 3 for Figure 2 Enlarged diagram of the middle section; Figure 4 for Figure 3 Schematic diagram of the middle section; Figure 5 This is a schematic diagram of the expandable support structure; Figure 6 This is a schematic diagram of the proximal or distal protective shell. Detailed Implementation

[0016] To facilitate understanding, we first define the orientation: "proximal" or "proximal" refers to the side closest to the operator / doctor, while "distal" or "distal" refers to the side furthest from the operator / doctor, i.e., the side closest to the heart. See the attached diagram for further details. Figures 1-6 The present invention will be described in further detail below.

[0017] like Figure 1 As shown, an interventional foldable left ventricular assist device includes a drive shaft 10, the proximal end of which is connected to a motor 20 and the distal end of which is connected to a pump head assembly. The pump head assembly includes a foldable impeller 30 driven by the drive shaft 10 and an expandable support 40 covering the outer periphery of the foldable impeller 30. The expandable support 40 is covered with a blood flow flexible membrane 50, the distal end of which forms a blood inlet a, and at least one bleeding outlet b is formed in its proximal region. In use, the entire pump head assembly is first folded and restrained within the sheath, then inserted into the femoral artery in a small-diameter state, passing through the aorta and aortic valve into the left ventricle. The sheath is then removed, and the pump head assembly expands due to the release of restraint. The foldable impeller 30 and expandable stent 40 are located within the left ventricle, while the flexible blood flow membrane 50 crosses the aortic valve, partially within the left ventricle and partially within the aorta. Power from the external motor 20 is transmitted to the internal foldable impeller 30 via the drive shaft 10. The rotating impeller 30 draws blood from the left ventricle into the inlet a and pumps it out through the outlet b into the aorta, increasing cardiac output, coronary perfusion, and reducing left ventricular preload and wall tension. As an interventional foldable left ventricular assist device, the pump head assembly must be folded back and restrained within the sheath before being removed from the body along with the sheath.

[0018] Furthermore, to meet the demands of blood circulation, interventional foldable left ventricular assist devices typically require a pumping flow rate of 2.5–6.5 L / min. Simultaneously, the rotation of the foldable impeller 30 can cause the rupture of red blood cells, leading to hemolysis. Hemolysis reduces the ability of red blood cells to transport oxygen to tissues and organs, potentially causing serious consequences such as kidney damage. Therefore, the design of interventional foldable left ventricular assist devices must minimize hemolysis as much as possible.

[0019] like Figure 2 , Figure 3 As shown, the flexible blood flow membrane 50 includes: a first channel 51 covering the cylindrical segment 41 of the expandable stent 40; The expansion section 52 connected to the proximal end of the first channel 51 has a diameter that gradually increases from distal to proximal. The expansion section 52 has at least the following beneficial effects: (1) When blood passes through the expansion section 52, the blood flow velocity will decrease due to the increased diameter, which directly reduces the shear force on the blood and thus significantly reduces the risk of hemolysis from the root cause; (2) Blood needs to be pumped into the aorta and flow to the whole body against the aortic pressure. The expansion section 52 can convert kinetic energy into pressure energy, increase the static pressure of the blood at the bleeding point a, and make the pumped blood more effectively overcome the aortic pressure and more smoothly integrate into the blood flow of the aorta; (3) The expansion section 52 provides a smooth and gradual flow path, guides the blood flow to decelerate smoothly, and the streamlined design minimizes turbulence and flow stagnation areas, reducing the risk of thrombosis; (4) After being processed by the expansion section 52, the blood flow distribution is more uniform, reducing the impact and damage to the aortic wall, and making the hemodynamics closer to the physiological state. Its proximal edge is located distal to the proximal edge of the expandable stent 40. After the blood is decelerated, the damage caused by impacting the inner wall of the stent is reduced, and hemolysis is further reduced.

[0020] And a second channel 53 connected to the proximal end of the expansion section 52. The diameter of the main body of the second channel 53 is equal to the maximum diameter of the expansion section 52. The proximal end of the second channel 53 is fixed to the conduit 60 sleeved outside the drive shaft 10. The bleeding port b is opened on the side wall near the proximal end of the second channel 53.

[0021] Furthermore, the length of the expansion section 52 is 2–5 mm, and the angle α between its generatrix and the device axis is 3–9°. The expansion of the interface of the flexible blood flow membrane 50 can reduce the flow velocity, minimizing turbulence at the outlet and reducing damage to the blood.

[0022] Preferably, there are two bleeding ports b, and when viewed from the distal end to the proximal end of the device, the two bleeding ports b have a right-handed spiral structure. Since the blood flows in a right-handed spiral as it is pumped towards the proximal end by the foldable impeller 30, setting the bleeding ports b to also be right-handed in the same direction as the blood rotation effectively counteracts the circumferential momentum at the outlet, reduces the impact on the blood vessel wall and the vibration of the device itself, and further optimizes blood compatibility and device stability.

[0023] like Figure 4 , Figure 5 As shown, the expandable stent 40 includes a cylindrical segment 41 and distal conical segments 42 and proximal conical segments 43 at both ends. The distal conical segments 42 and proximal conical segments 43 have an asymmetrical structure, with the angle between the proximal conical segment 43 and the axis of the cylindrical segment 41 being smaller than the angle between the distal conical segment 42 and the axis of the cylindrical segment 41. The proximal conical segment 43 is longer and more gently sloping. During retrieval, the sheath converges from the proximal end to the distal end. This structure provides guidance and stress buffering, making the entire retrieval process controllable, smooth, and reliable. Furthermore, in terms of blood compatibility, the gently sloping stent significantly reduces the direct impact force and shear rate of blood flow on the stent, fundamentally reducing mechanical hemolysis in this area.

[0024] Furthermore, the first channel 51 is formed by bonding and fixing an inner membrane and an outer membrane placed on the inner and outer surfaces of the cylindrical segment 41 through a hot-melt process. The inner membrane can be a dip-molded membrane or a finished tubular membrane. The distal and proximal edges of the inner membrane are flush with the distal and proximal edges of the cylindrical segment 41, respectively. The outer membrane extends from the proximal edge of the cylindrical segment 41 to the proximal end and sequentially forms the expansion segment 52 and the second channel 53.

[0025] The distal conical section 42 and the proximal conical section 43 each have eight legs c. The width of each leg c gradually narrows from its tip toward the cylindrical section 41. The area closer to the cylindrical end 41 experiences greater deformation during expansion and folding. Therefore, this width design is beneficial for the folding of the entire expandable support 40. Each leg c has a foot d at its end. The foot d and the corresponding slot e on the proximal shell 44 or the distal shell 45 form an inverted interlocking structure. The outer wall of the section where the slot e and the foot d interlock is fitted with a shell steel ring 46 and fixed with adhesive. The gap between the foot d and the shell steel ring 46 is filled with adhesive, and the edges are smooth to avoid gaps and sharp corners that could cause hemolysis.

[0026] The foldable impeller 30 is injection molded from TPU material and includes a hub 31 and multiple blades 32 disposed on the surface of the hub 31. The root portion of the blades 32 is perpendicular to the surface of the hub 31. When an external force is applied to fold the blades 32, bending will preferentially occur at this vertical root. The stress is concentrated at this pre-designed position, guiding the blades 32 to fold neatly backward from this position, avoiding random and chaotic bending of the blades 32 at other unpredictable positions, thus achieving controllable and orderly folding. Furthermore, the twisting direction of the blades 32 located on the impeller inlet side is opposite to the rotation direction of the foldable impeller 30. That is, in a stationary state, the blades 32 do not extend forward but sweep backward. When folding backward from their vertical root, their movement direction is highly coordinated with the twisting direction of the blades 32 themselves, naturally adhering to the central axis of the hub 31 or the space behind it. The combination of these two features greatly reduces the force required for this process, ensuring a smaller and more regular profile after folding, and minimizing fatigue damage to the blades 32 during the anti-folding-unfolding-folding process.

[0027] Furthermore, the distal edge of the blade 32 is located near the distal edge of the cylindrical section 41, with an axial distance L between them of 1.5–2.5 mm. This prevents the foldable impeller 30 from shifting beyond the film-covered position due to the reverse force of blood flow during operation. The thickness of the blade 32 gradually decreases from the inlet end to the outlet end, ranging from 0.25–0.35 mm. From a fluid dynamics perspective, a thicker, more robust leading edge can better withstand the impact of blood flow, smoothly guiding blood to adhere to the surface of the blade 32, preventing flow separation, and thus reducing energy loss and turbulence. When the blood flow is accelerated and directed to the outlet, a thin trailing edge allows for easier convergence of blood flow, minimizing wake eddies and resistance. From a folding performance perspective, the sheath folds and converges the pump body from the proximal end to the distal end; the thinner blades at the proximal end facilitate convergence, making the entire recovery process smoother.

[0028] Under high afterload pressure, the foldable impeller 30 will deform slightly. When the device is expanded and unfolded, the gap between the blade tip of the blade 32 and the inner wall of the inner membrane is less than 0.3mm, preventing the blade 32 from contacting the inner membrane.

[0029] like Figure 4 , Figure 6 As shown, the drive shaft 10 includes a flexible shaft 11 at the proximal end and a rigid shaft 12 at the distal end. The foldable impeller 30 is fixedly mounted on the rigid shaft 12, and the proximal end of the rigid shaft 12 forms a supporting rotational engagement with the proximal end housing 44, while the distal end of the rigid shaft 12 forms an axial sliding and circumferential rotational engagement with the distal end housing 45. In the folded state, the axial length of the expandable support 40 is adapted to this change through the sliding engagement between the distal end of the rigid shaft 12 and the distal end housing 45.

[0030] 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.

[0031] 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. An interventional foldable left ventricular assist device, comprising a drive shaft (10), the proximal end of the drive shaft (10) being connected to a motor (20) and the distal end being connected to a pump head assembly, the pump head assembly comprising a foldable impeller (30) driven by the drive shaft (10) and an expandable support (40) covering the periphery of the foldable impeller (30); the expandable support (40) is covered with a blood flow flexible membrane (50), the distal end of the blood flow flexible membrane (50) forming a blood inlet (a), and at least one bleeding outlet (b) being formed in its proximal region; Its features are, The blood flow flexible membrane (50) includes: The first channel (51) is covered on the cylindrical section (41) of the expandable support (40). An expansion section (52) is connected to the proximal end of the first channel (51). The diameter of the expansion section (52) gradually increases from distal to proximal, and its proximal edge is located distal to the proximal edge of the expandable support (40). And a second channel (53) connected to the proximal end of the expansion section (52), the main body diameter of the second channel (53) is equal to the maximum diameter of the expansion section (52), the proximal end of the second channel (53) is fixed to a conduit (60) sleeved outside the drive shaft (10), and the bleeding port (b) is opened on the side wall near the proximal end of the second channel (53).

2. The interventional foldable left ventricular assist device according to claim 1, characterized in that: The length of the expansion section (52) is 2 to 5 mm, and the angle α between its generatrix and the axis of the device is 3 to 9°.

3. The interventional foldable left ventricular assist device according to claim 1, characterized in that: There are two bleeding openings (b). When viewed from the far end to the near end of the device, the two bleeding openings (b) have a right-handed spiral structure.

4. The interventional foldable left ventricular assist device according to claim 1, characterized in that: The expansion support (40) includes a cylindrical segment (41) and a distal conical segment (42) and a proximal conical segment (43) at both ends; wherein the distal conical segment (42) and the proximal conical segment (43) are asymmetrical structures, and the angle between the axis of the proximal conical segment (43) and the axis of the cylindrical segment (41) is smaller than the angle between the axis of the distal conical segment (42) and the axis of the cylindrical segment (41).

5. The interventional foldable left ventricular assist device according to claim 1 or 4, characterized in that: The first channel (51) is formed by bonding and fixing an inner membrane and an outer membrane placed on the inner and outer surfaces of the cylindrical segment (41) by a hot melt process; the distal and proximal edges of the inner membrane are flush with the distal and proximal edges of the cylindrical segment (41) respectively, and the outer membrane extends from the proximal edge of the cylindrical segment (41) to the proximal end, and sequentially forms an expansion segment (52) and a second channel (53).

6. The interventional foldable left ventricular assist device according to claim 4, characterized in that: The distal conical section (42) and the proximal conical section (43) each have eight legs (c), and the width of each leg (c) gradually narrows from its tip toward the cylindrical section (41); each leg (c) is provided with a foot (d) at its end, and the foot (d) and the corresponding slot (e) on the proximal shell (44) or the distal shell (45) form an inverted snap structure fit, and the outer wall of the fitting section of the slot (e) and the foot (d) is fitted with a shell steel ring (46) and fixed by adhesive.

7. The interventional foldable left ventricular assist device according to claim 1, characterized in that: The foldable impeller (30) is injection molded from TPU material and includes a hub (31) and multiple blades (32) disposed on the surface of the hub (31). The root portion of the blades (32) is perpendicular to the surface of the hub (31), and the twisting direction of the blades (32) located on the impeller inlet side is opposite to the rotation direction of the foldable impeller (30).

8. The interventional foldable left ventricular assist device according to claim 7, characterized in that: The distal edge of the blade (32) is located near the distal edge of the cylindrical section (41), and the axial distance L between the two is 1.5 to 2.5 mm. The thickness of the blade (32) gradually decreases from the inlet end to the outlet end, and its thickness ranges from 0.25 to 0.35 mm.

9. The interventional foldable left ventricular assist device according to claim 5 or 8, characterized in that: When the device is in the expanded state, the gap between the blade tip (32) and the inner wall of the inner membrane is less than 0.3 mm.

10. The interventional foldable left ventricular assist device according to claim 1 or 6, characterized in that: The drive shaft (10) includes a flexible shaft (11) at the proximal end and a rigid shaft (12) at the distal end. A foldable impeller (30) is fixedly installed on the rigid shaft (12). The proximal end of the rigid shaft (12) and the proximal end housing (44) form a support rotational fit, and the distal end of the rigid shaft (12) and the distal end housing (45) form an axial sliding and circumferential rotational fit.

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