DESC:FIELD OF INVENTION
[0001] The present disclosure relates to the field of medical devices. Particularly, to impeller configurations for catheter-based blood pumps used to provide circulatory support, and more particularly to an impeller apparatus, system, and method for optimizing blood flow and reducing hemolysis in percutaneous ventricular assist devices (PVADs), thereby improving catheter-based blood pump performance, reduces blood stagnation and hemolysis for minimal invasive circulatory support systems.
BACKGROUND OF THE INVENTION
[0002] Heart failure is a life-threatening condition in which the heart is unable to pump sufficient blood throughout the body. This inadequate blood supply disrupts normal organ function and can ultimately lead to multi-organ failure, resulting in death. Every year, tens of millions of patients globally die as a result of heart failure. Current treatment options for heart failure include medication, heart transplantation, and mechanical circulatory support therapies such as ventricular assist devices (VADs).
[0003] Ventricular assist devices are types of blood pumps used for both short-term (2-12 months) and long-term (10-12 years) applications, mainly as a bridge-to-transplant or destination therapy where a patient's heart is incapable of providing adequate circulation. VADs can be used while a patient awaits a heart transplant, known as bridge-to-transplant. Alternatively, a VAD may be used as a destination therapy if heart transplant is not an option due to economic reasons or scarcity of donors, allowing some heart failure patients to have the device implanted for permanent use.
[0004] VADs can be implanted in the patient's body and powered by an electrical power source outside the patient's body. Most commonly, VADs are impeller-driven pumps powered by an integrated electric motor. Through the high-speed rotation of the impeller, energy is transferred to the blood, propelling it to flow with sufficient force to meet the body's circulatory demands. This mechanical support is crucial for restoring hemodynamic stability in patients with weakened cardiac function. However, stagnation regions where blood achieves zero velocity can lead to clotting, known as thrombosis. Additionally, hemolysis refers to the rupture of red blood cells due to high shear stress, thereby releasing hemoglobin and rendering red blood cells ineffective.
[0005] The development of percutaneous ventricular assist devices (PVADs) represents a significant advancement in heart failure treatment. Unlike traditional VADs, which require open-chest surgery for implantation, PVADs can be inserted through minimally invasive procedures via the femoral or carotid artery, thus reducing surgical risk, implantation time, and recovery time for patients. These devices are designed to be deployed via catheterization, making them suitable for high-risk Percutaneous Coronary Intervention (PCI) candidates who may not be suitable for more invasive surgical interventions.
[0006] The ability of PVADs to provide temporary circulatory support, ranging from 8 hours to 7 days, during high-risk PCI procedures or during cardiogenic shock makes them an essential tool in modern heart failure management. As the demand for effective, minimally invasive cardiac support devices grows, innovations in the design and function of PVADs, particularly in the area of blood pump performance for fewer stagnation regions and reduced hemolysis, are essential to improve patient outcomes and expand the range of therapeutic options for heart failure treatment.
[0007] The design of existing impeller-based blood pumps faces significant constraints due to several critical factors. These include the size of the blood vessels through which the device must be inserted, the method of intervention, as well as the need to minimize hemolysis and thrombosis. These constraints impose substantial limitations on the size, shape, and rotational speed of the impeller, ultimately affecting the device's overall efficiency and performance.
[0008] One of the major challenges is to increase the blood flow rate and the pressure generated by the blood pump while maintaining compact impeller geometry and controlled rotational speed. Inadequate optimization of these parameters can result in insufficient circulatory support or excessive mechanical stress on blood cells, potentially leading to hemolysis, thrombosis, or device failure.
[0009] In existing technologies, particularly in axial-flow blood pumps, the blades of the impeller are typically wound on a helical or cylindrical surface. While this basic design is functional, it remains relatively simplistic and does not substantially improve the pump's performance in terms of flow rate, efficiency, reduced thrombosis, and hemolysis. The simple blade configuration, often found in conventional axial-flow designs, fails to adequately meet these needs.
[0010] Various patent applications disclose catheter-based blood pumps with different impeller designs and configurations aimed at addressing these challenges. One patent application US9675740B2 discloses a blood pump impeller designed to reduce hemolysis and improve pump efficiency. The impeller includes a hub with a plurality of blades, wherein each blade has a varying thickness to optimize blood flow and reduce shear stress on blood cells. However, the cited document primarily focuses on blade thickness variation without addressing other critical aspects of impeller geometry, such as blade curvature, sweep angles, or hub-less configurations.
[0011] Another patent application US9265870B2 discloses a rotary blood pumps consists of a hub and blade having a specific curvature which creates a localized flow field that reduces blood stagnation and recirculation, the invention focuses on an impeller design for rotary blood pumps, particularly aimed at reducing the risk of thrombosis. However, the cited document fails to address the issue of hemolysis, as the focus on reducing thrombosis through curvature alone may not sufficiently mitigate the shear stresses experienced by red blood cells during pump operation.
[0012] Therefore, to overcome the limitations of existing technologies, there is a critical need to develop innovative blood pump designs that optimize flow rate, pressure generation, and efficiency while simultaneously reducing thrombosis and hemolysis within the anatomical and procedural constraints of catheter-based interventions. A comprehensive approach that considers multiple geometric parameters, including blade sweep angles, hub-less configurations, blade thickness distributions, curvature optimization, and advanced flow navigation systems, may provide a more effective solution for improving circulatory support while minimizing blood trauma in percutaneous ventricular assist devices.

OBJECTIVE OF THE INVENTION
[0013] The primary objective of the present invention is to provide an optimized impeller configuration for catheter-based blood pumps that enhances blood flow performance while minimizing hemolysis and thrombosis risks in percutaneous ventricular assist devices (PVADs);
[0014] Another objective of the present invention is to develop an impeller design that incorporates advanced geometric features, including optimized blade sweep angles, hub-less configurations, and variable blade thickness distributions, to improve overall pump efficiency within the size constraints of catheter-based interventions;
[0015] Another objective of the present invention is to provide a novel flow navigation system that works in conjunction with the optimized impeller to better direct blood flow, reduce stagnation regions, and enhance the conversion of kinetic energy to pressure energy within the pump assembly;
[0016] Another objective of the invention is to provide a catheter-based blood pump to achieve higher flow rates and pressure generation while maintaining controlled rotational speeds and compact dimensions suitable for minimally invasive deployment;
[0017] Yet another objective of the invention is to provide a comprehensive solution that addresses multiple aspects of blood pump performance, including flow optimization, hemolysis reduction, and thrombosis prevention, thereby improving the overall efficacy and safety of PVADs for temporary circulatory support during high-risk procedures or in cases of cardiogenic shock;
[0018] Yet another objective of the present invention is to enhance the durability and longevity of the catheter-based blood pump by incorporating materials and design features that reduce wear and fatigue, potentially extending the operational lifespan of the device during temporary circulatory support applications.
[0019] Yet another objective of the present invention to develop an impeller configuration that facilitate easier insertion and retrieval of the catheter-based blood pump, potentially improving the ease of use for clinicians and reducing procedural time and complexity.
[0020] Yet another objective of the present invention to optimize the impeller design to potentially accommodate a wider range of patient anatomies and physiological conditions, which increase the applicability of the device across diverse patient populations requiring circulatory support.
[0021] Other objectives and advantages of the present invention will become apparent from the following description taken in connection with the accompanying drawings, wherein, by way of illustration and example, the aspects of the present invention are disclosed.
SUMMARY OF THE INVENTION
[0022] The present invention relates to an impeller apparatus for a catheter-based blood pump. The impeller apparatus comprises, at least two impeller blades with three-dimensional curved surfaces, wherein each impeller blade has a leading edge and a trailing edge, and a variable thickness distribution with a maximum thickness location positioned between the leading edge and the trailing edge. The impeller blades have a first sweep angle at the leading edge and a second sweep angle at the trailing edge, as well as a sweep structure at the leading edge and a wrap angle defining degrees by which the blade is wrapped. The impeller apparatus is configured in either a hubbed configuration with a central hub supporting the impeller blades, or a hub-less configuration with the impeller blades arranged circumferentially around a central axis. The apparatus further includes a flow navigator positioned downstream of the impeller blades, comprising guide vanes configured to direct blood flow, and a fluid channel configured to provide a fluid-based sealing mechanism to prevent blood ingress into critical areas, thereby enhancing pump efficiency, and improves hem compatibility. The variable blade geometry and configurable hub options allow for customization to specific patient needs and clinical requirements, while the flow navigator and fluid-based sealing mechanism work together to reduce turbulence, minimize energy loss, and prevent blood damage or contamination of critical components.
BRIEF DESCRIPTION OF FIGURES

[0023] The present invention will be better understood after reading the following detailed description of the presently preferred aspects thereof with reference to the appended drawings, in which the features, other aspects and advantages of certain exemplary embodiments of the invention will be more apparent from the accompanying drawing in which:
[0024] Figure 1 illustrates a side view of an impeller design for a catheter-based blood pump;
[0025] Figure 2 depicts a side orthogonal view of an impeller for a catheter-based blood pump;
[0026] Figure 3 illustrates a cross-sectional view of an impeller design;
[0027] Figure 4 illustrates a meridional view showing sweep angles of a catheter pump impeller;
[0028] Figure 5 depicts an orthogonal side view of an impeller blade configuration. The figure illustrates the wrap angle and blade thickness of a catheter pump impeller, showing the geometric relationship between the blade leading edge and blade trailing edge;
[0029] Figure 6 illustrates a side view of blade angles at leading and trailing edges of a blood pump impeller;
[0030] Figure 7 illustrates a graph of thickness distribution along the blade length of a catheter pump impeller;
[0031] Figure 8 depicts a graph of thickness distribution at different span-wise locations from leading edge to trailing edge of a catheter pump impeller;
[0032] Figure 9 shows an isometric leading-edge view of a hub-less impeller configuration.
[0033] Figure 10 illustrates an isometric trailing edge view of a hub-less impeller configuration;
[0034] Figure 11 depicts a side view of a hub-less impeller design;
[0035] Figure 12 shows a cross-sectional view of a hub-less impeller design;
[0036] Figure 13 illustrates an isometric view of a flow navigator for a catheter-based blood pump;
[0037] Figure 14 depicts an orthogonal view of a flow navigator component;
[0038] Figure 15 shows a cross-sectional view of a blood pump assembly.
[0039] Figure 16 illustrates a cross-sectional view of a catheter pump assembly;
[0040] Figure 17 depicts a section view of a blood pump assembly showing internal components;
[0041] Figure18 shows a cross-sectional view of a catheter pump assembly with internal components;
[0042] Figure 19 illustrates a cross-sectional view of a flow navigator assembly;
[0043] Figure 20 depicts a velocity triangle diagram for an impeller blade and guide vanes;
[0044] Figure 21 shows a side orthogonal view of an impeller design with a teardrop-shaped profile;
[0045] Figure 22 illustrates a side view of an impeller blade design showing key geometric features.
[0046] Common reference numerals are used throughout the figures to indicate similar features.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
[0047] The following description describes various features and functions of the disclosed system. The illustrative aspects described herein are not meant to be limiting. It may be readily understood that certain aspects of the disclosed system can be arranged and combined in a wide variety of different configurations, all of which have not been contemplated herein.
[0048] Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope of invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.
[0049] Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.
[0050] The terms and words used in the following description are not limited to the bibliographical meanings, but, are merely used to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustrative purposes only and not for the purpose of limiting the invention.
[0051] It is to be understood that the singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise.
[0052] It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, steps or components but does not preclude the presence or addition of one or more other features, steps, components or groups thereof. The equations used in the specification are only for computation purpose.
[0053] Accordingly, the present disclosure relates to the field of medical devices. Particularly, to impeller configurations for catheter-based blood pumps used to provide circulatory support, and more particularly to an impeller apparatus, and method for optimizing blood flow and reducing hemolysis in percutaneous ventricular assist devices (PVADs), thereby improving catheter-based blood pump performance, reduces blood stagnation and hemolysis for minimal invasive circulatory support systems.
[0054] In the present invention, the impeller apparatus (145) for a catheter-based blood pump, comprising: at least two impeller blades (111) with three-dimensional curved surfaces; a flow navigator (146) positioned downstream of the impeller blades (111), the flow navigator (146) comprising guide vanes (138) configured to direct blood flow; and a fluid channel (149) configured to provide a fluid-based sealing mechanism to prevent blood ingress into critical areas, improving pump efficiency, reducing blood stagnation, and minimizing hemolysis. The impeller aimed to improve the overall performance of percutaneous ventricular assist devices (PVADs) by optimizing blood flow dynamics while maintaining biocompatibility and minimizing mechanical stress on blood cells.
[0055] The impeller apparatus (145) is available in two configurations: a hubbed impeller with a central hub supporting the impeller blades and a hub-less impeller with the impeller blades arranged circumferentially around a central axis. Both configurations are designed to enhance blood flow efficiency while reducing shear stress on blood cells, thereby minimizing hemolysis and thrombosis.
[0056] (A) Hubbed impeller: The hubbed impeller comprises a central hub (110) with at least two impeller blades spirally wrapped around it, as shown in figure 1 to 3. The central hub (110) comprises three distinct sections designed to optimize blood flow and minimize turbulence:
i. At an upstream side, the central hub (110) features a spherical dome (113), as illustrated in figure 3. The dome-shaped structure facilitates smooth blood entry into the impeller apparatus (145), reducing flow separation and turbulence. The spherical dome (113) have a radius ranging from 1 mm to 5 mm.
ii. The middle section of the central hub (110) transitions into a truncated cone (114) with an increasing radius, as shown in figure 3. This gradual expansion helps streamline blood flow through the impeller apparatus (145).
[0057] At the downstream side, the central hub (110) incorporates a curved, expanding conical shape (117) with a parabolic profile, as depicted in figure 3. This design ensures smooth blood exit from the impeller apparatus (145) with minimal turbulence and flow separation. In an exemplary embodiment, the spherical dome (113) have a radius ranging from 1 mm to 5 mm, the truncated cone (114) have a length of 5 mm to 15 mm and an angle of expansion ranging from 5 to 15 degrees and the curved conical structure (117) extend from 3 mm to 8 mm and have a maximum radius 1.5 to 2.5 times larger than the radius at the distal end (115).
[0058] As illustrated in figure 1 to 3, the impeller apparatus (145) comprises a hub (110) and at least two blades (111) spirally wound around the hub (110). The front section of the hub (110) has a spherical or approximately spherical dome (113), formed by rounding the outer edge of a cylindrical structure. The rounded front section allow blood to enter the pump smoothly, minimizing turbulence and enhancing laminar flow for improved efficiency. The middle section of the hub transitions into a truncated cone shape (114), with the radius gradually expanding from the distal end (115) to the proximal end (116). The conical structure ensures efficient blood flow from the leading edge to the impeller's working sections, maintaining attached flow while reducing energy loss. The rear section of the hub (110) features a curved conical structure (117) with a parabolic profile, and the radius continues to increase, facilitating a controlled and smooth exit of blood from the pump assembly.
[0059] The impeller blades (111) consist of at least two continuous blades, each featuring a three-dimensional curved surface. The contour lines of the blade surfaces are defined by four key elements: the leading edge (118); the outer edge contour line (119); the hub contour line (120); and the trailing edge (121). Both the leading edge (118) and the trailing edge (121) are straight lines, and the outer edge contour line (119) and the hub contour line (120) are represented by gradually transitioning exponential arcs or Bezier curve arcs, providing smooth transitions between the blade surfaces, potentially improving flow dynamics and optimizing blood flow through the impeller. The blade geometry is designed to minimize flow separation at the leading edges and ensure smooth blood exit with minimal turbulence at the trailing edges, as analyzed and validated by Computational Fluid Dynamics (CFD).
[0060] Figure 4 illustrates the meridional view of the catheter pump impeller (145), highlighting the leading (122) and trailing (123) edge sweep angles. In another exemplary embodiment, the leading-edge sweep angle (122) is in the range of -40 to 20 degrees, optimize fluid dynamics and pump efficiency by controlling how blood enters the blade channels. This reduce flow separation, turbulence, and shear stress, potentially improving stability, minimizing the risk of hemolysis, and enhancing biocompatibility. In another exemplary embodiment, the trailing-edge sweep angle (123) is in the range of -60 and 0 degrees, may facilitate smooth blood exit from the impeller (145), potentially reducing turbulence, energy loss, drag, and shear stress.
[0061] Figure 5 illustrates the wrap angle (126) and thickness of the catheter pump impeller (145). The wrap angle (126) refers to the angular span covered by the impeller blades (111) around the axis of rotation (124). In an exemplary embodiment, the improved wrap angle is in the range of 45° to 360°. Further, the parameter may influence the pump's performance, including efficiency, flow dynamics, and hemocompatibility. The wrap angle parameters has been developed through iterative Computational Fluid Dynamics (CFD) and bench test experiments.
[0062] Figure 6 illustrates the blade angles at the leading and trailing edges of the catheter pump impeller (145). The blade angle affect blood propulsion efficiency and hemocompatibility. Two key angles of the blade geometry are the leading edge angle (128) near the leading edge (112) and the trailing edge angle (129) near the trailing edge (125). The leading edge blade angle (128) influences blood entry into the impeller. In an exemplary embodiment, the optimized leading edge angle is in the range of 20° to 50° that may promote smooth, disturbance-free flow, potentially reducing stagnation and high shear stress that may affect blood cells. The trailing edge blade angle (129) affects blood exit from the impeller, influencing pressure generation and flow velocity. In another exemplary embodiment the shallower trailing edge angle ranging from 50° to 80° may enable smooth outflow with reduced turbulence.
[0063] Referring to Figure 7 and Figure 8, the distribution of blade thickness (127) from the leading edge (112) to the trailing edge (125) is designed via CFD to enhance fluid dynamics and structural integrity in catheter pump impellers. In an exemplary embodiment, the thickness begins minimal at the leading edge (112), typically around 2% to 5% of the chord length. The maximum blade thickness is positioned at 30% to 50% of the chord length from the leading edge. At the trailing edge (125), the blade tapers to its thinnest point, typically around 0.5% to 2% of the chord length. Near the hub side (131), the blade thickness is at its maximum, gradually decreasing to 70% to 80% of the maximum thickness by mid-span (132). Near the tip side (133), the blade reaches its thinnest section, typically 30% to 50% of the thickness of blade at the hub side (131).
[0064] (B) Hub-less Impeller (136) configuration: In the hub-less configuration (136), the central hub is eliminated, allowing for a larger effective flow area. The hub-less configuration (136) reduce blood flow disruption and improve laminar flow through the pump. The blades are arranged circumferentially around a central axis and are optimized in terms of curvature and geometry to promote smooth blood flow with minimal turbulence. The absence of a central hub may allow for lower rotational speeds while maintaining high flow rates, potentially reducing mechanical stress on blood cells and power requirements of the blood pump
[0065] Referring to figure 9 to 12, the hub less impeller (136) features a series of circumferentially arranged blades (111) extending radially from a central axis, without a central hub. These blades (111) are supported at their outer edges by a support ring (134), leaving the central region unobstructed to allow blood flow. The blades (111) are designed with aerodynamic profiles that may enhance blood flow by reducing turbulence and promoting laminar flow. The blade geometry include distinct leading edges (112) and trailing edges (125), used to minimize pressure differentials and reduce the risk of blood cell damage, such as hemolysis. In an exemplary embodiment, the impeller blades (111) feature a variable pitch, where the angle of the blades (111) changes relative to the direction of flow from the base to the tip. The spacing between the blades (111) are configured to prevent cavitation, allowing fluid passage with minimal resistance.
[0066] The hub less impeller's blades are connected to a support ring (134) to maintain the structural integrity of the impeller without requiring a central hub. The support ring (134) help the blades (111) to remain rigid during operation, even at high rotational speeds, potentially ensuring consistent performance and reliability.
[0067] The hub-less impeller (136) rotate within the casing, driven by either a magnetic or mechanical coupling mechanism. Upon rotation, the blades transfer kinetic energy to the blood, directing it from the leading edge to the trailing edge of the pump with minimal hydraulic resistance. The blade geometry are configured to maintain blood flow, supporting ventricular support. In exemplary embodiments, the hub-less impeller (136) provide advantages over conventional hubbed designs: (a) by operating at lower speeds for a given flow rate due to the increased effective flow area, potentially reducing complications such as thrombosis and hemolysis; (b) providing hemodynamic performance with reduced blood damage; (c) functioning with mechanical efficiency, requiring lower power consumption while achieving flow efficiency; and (d) creating create a blood flow passage with reduced recirculation and stagnation zones, potentially lowering the risk of thrombus formation. The configuration increase the net flow area available within the blood pump, minimize flow disturbances, optimize energy transfer, and enhance the overall efficiency of the device in providing circulatory assistance.
[0068] (C) Flow Navigator (146): The flow navigator (146), is positioned downstream of the impeller. The flow navigator (146) comprises guide vanes (138) and guide stator (139) and guide vanes (138). In an exemplary embodiment, the guide vanes (138) twisted in the same or opposite direction as the flow angle at the trailing edge of the impeller blades. The guide vanes (138) help convert kinetic energy into pressure energy, potentially improving the overall pressure generation of the pump. Further, the flow navigator (146) facilitate smooth navigation of blood from the impeller into the aorta while maintaining streamlined flow and reducing turbulence. The flow navigator (138) near the outflow end is oriented axially, which reduce turbulence, minimize energy loss, and promote consistent blood outflow, potentially improving overall pump efficiency as shown in figure 13 to 14.
[0069] Referring to figure 13 to 14, the present invention describes a catheter pump device comprising a motor (144), an impeller (145), and a flow navigator (146). The impeller (145) and flow navigator (146) are housed within the outflow connector (146). The impeller (145), driven by a proximal motor (144), features blades (111) that rotate in one direction.
[0070] Referring to figure15 and 16, at least a portion of the circumferential area of the flow navigator (146) is fixed to the inner wall of the outflow connector (143). The number of guide vanes (138) and impeller blades (111) are designed to be coprime, with guide vanes (138). The flow navigator (146) has a second twisting direction opposite to the first twisting direction of the impeller blades (111), and at least a portion of the flow navigator (146) near the outflow end extends substantially in the axial direction to reduce turbulence. The guide stator (139) also includes a hole (147) to accommodate the motor transmission.
[0071] In an exemplary embodiment, the distance between the flow navigator (146) and the impeller blade (111) is set to 0.05 to 0.1 times the diameter of the guide stator (139), which enhance flow dynamics and pump efficiency. The leading edge area of the navigator (140) and the guide stator (139) is shaped like a circular truncated cone, with dimensions matching the trailing edge of the impeller hub (110). The proximal edges (116) of the impeller blades (111) and the distal edges of the guide vanes (38) are oriented perpendicular to the central axis of the impeller (145).
[0072] The axial surface velocity at the flow navigator (146) leading edge is designed to match the axial surface velocity at the impeller blade (111) trailing edge. Further, the circumferential component of the liquid's absolute velocity at the flow navigator (146) leading edge is equal to the circumferential component of the liquid's absolute velocity at the impeller blade trailing edge, enabling smooth flow transition, minimize energy loss, and enhance overall pump efficiency.
[0073] The flow navigator (146) is positioned at the trailing edge of the impeller (145), with the twisting directions of the flow navigator (146) and the impeller blade (111) at the leading edge being opposite or similar. As blood exits the blade (111), it rotates in the second twisting direction, aligns with the twisting of the flow navigator (146) at its far end, allowing smooth reception and guidance of the blood. The configuration prevent blood from colliding with the flow navigator (146), avoiding disruption of the flow field. Near the outflow end, the flow navigator (146) closely aligns with the axial direction, and reduce the rotating flow field, minimize energy loss, and help ensure the blood's outflow is consistent with the axial direction for improved efficiency.
[0074] In another embodiment, the flow navigator (146) comprises guide stator vanes and are twisted in alignment with the flow angle at the stationary frame on the trailing edge of the impeller blades (111) with slight adjustments in the range of 2° to 5°. In an exemplary embodiment, the wrap angle of these guide vanes ranges from 90° to 160°, allowing the flow velocity at entry to the guide vanes to match the absolute velocity at exit from the trailing edges of the impeller blades. The guide stator has a circular truncated cone shape, with its upstream side diameter matching that of the impeller hub exit diameter. Additionally, it includes a hole allowing passage of the motor shaft. The downstream section of the impeller extends axially based on a specified diffusion rate determined by an angle of divergence ranging from 7° to 10°.
[0075] In an alternative embodiment, as illustrated in figure 17 to 19, the flow navigator assembly (142) is integrated with the outflow connector (143) and motor casing into a unified assembly. The motor (144) is housed within the motor casing (148), supporting alignment and efficient operation. The motor shaft (137) extends through a precisely machined shaft hole (147) in the flow navigator assembly (142), facilitating smooth rotation with minimal friction. The impeller (145) is affixed to the motor shaft (137) and is positioned near the leading edge area of the outflow area of flow navigator assembly (142). The entire assembly, comprising the flow navigator assembly (142) and impeller (145), is encased within the outflow connector (143). The configuration provide structural integrity and create a sealed environment that protects the motor components from exposure to blood.
[0076] Referring to Figure 20, Outlet velocity triangle at trailing edge of the impeller serves as an inlet velocity triangle at leading edge of the guide vanes of the flow navigator. The absolute flow ideally exits from the impeller at the same angle (a2) as that of the guide vane.
[0077] (D) Fluid-based sealing mechanism: The fluid-based sealing mechanism comprises a microchannel, to address the challenges related to blood entering areas such as motor bearings or spaces between components along with flushing any blood getting stagnated faced in catheter-based pumps. Fluid based sealing channel facilitates a continuous flow of a biocompatible fluid seal through the motor casing (148) and into the shaft hole (147) of the flow navigator assembly (142). The fluid seal enters the shaft region via flow navigator and wash away any blood, preventing it from coming into contact with the rotating motor shaft and surrounding parts. Further, mechanical seals used in micro brushless DC (BLDC) motors ranging from 3mm to 5mm, reduce the available torque, thereby potentially impairing the overall efficiency of blood pumps.
[0078] In another embodiment, fluid seal utilizes the microchannel via a hypotube to enable continuous flow of a biocompatible fluid, which are mixed with heparin, over or through the motor casing. This fluid is introduced via a hypotube, and passes through a hole in the flow navigator. In an exemplary embodiment, the hypo tubes are commercially available biocompatible tubes with outer diameters ranging from 0.1mm to 0.5mm and thicknesses in the range of 0.01mm and 0.1mm. The fluid enters through this hole, flows into the space between the flow navigator and the shaft, and exits through the gap between the impeller and flow navigator. The pressure of this fluid seal are adjusted within a range of 60 mm Hg to 500 mm Hg, depending on operational requirements.
[0079] (E)Teardrop Hub Design: As illustrated in figure 21 and figure 22, the teardrop hub (150) impeller features a central hub with a teardrop-shaped profile, designed to enhance fluid dynamics and reduce turbulence across various applications. The hub's broad front section allow smooth fluid entry, while its gradual tapering aligns with natural flow paths, potentially reducing flow separation and drag to improve energy efficiency. Surrounding the hub are helically arranged impeller blades (111) with specific solidity and curvature, designed for consistent flow rates and effective pressure generation. The above design reduce shear stress and blood stagnation, potentially lowering risks of hemolysis and thrombosis in blood-handling applications. The symmetrical teardrop profile provide uniform stress distribution, enhancing the impeller's durability and operational longevity.
[0080] In an embodiment, the advantages of the present invention are discussed herein:
• The present invention is to provide a three-dimensional curved surfaces of the impeller blades promote smooth, laminar blood flow through the pump, reducing turbulence and minimizing areas of stagnation;
• The impeller blade geometry including optimized sweep angles and thickness distribution, minimizes shear stress on blood cells, reducing the risk of hemolysis during pump operation;
• The impeller configuration combined with the flow navigator, allows for efficient energy transfer from the impeller to the blood, resulting in improved overall pump performance.
• The streamlined design of the impeller and flow navigator reduces areas of blood stagnation, lowering the risk of thrombus formation within the pump.
• The impeller apparatus is configured in either a hubbed or hub-less design, allowing for customization based on specific clinical requirements and patient anatomy.
• The optimized impeller configuration allows for a smaller overall pump size, facilitating minimally invasive insertion and placement within the cardiovascular system.
• The flow navigator with guide vanes enables precise direction of blood flow and conversion of kinetic energy to pressure energy, enhancing the pump's ability to provide adequate circulatory support.
• The efficient impeller design results in lower power requirements for pump operation, potentially extending battery life in portable systems.
• The optimized blade geometry and flow characteristics reduce wear on pump components, potentially increasing the device's operational lifespan.
• The fluid-based sealing mechanism helps prevent blood ingress into critical areas of the pump, reducing the risk of blood damage and improving overall biocompatibility.
• The impeller apparatus is used in various catheter-based blood pump applications, including short-term and long-term circulatory support devices.
• The impeller configuration allows for effective pressure generation while maintaining gentle handling of blood cells, balancing pump performance with hemocompatibility.
• The flow navigator helps to minimize backflow and recirculation zones, improving the overall efficiency of blood transport through the pump.
• The impeller apparatus is compressed for insertion through blood vessels, allowing for minimally invasive deployment. After insertion, the impeller apparatus expand to its operational configuration, facilitating proper pump function while minimizing trauma during placement.
[0081] While this invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.
,CLAIMS:WE CLAIM:
1. An impeller apparatus (145) for a catheter-based blood pump, comprising:
• at least two impeller blades (111) with three-dimensional curved surfaces;
• a flow navigator (146) positioned downstream of the impeller blades (111), the flow navigator (146) comprising guide vanes (138) configured to direct blood flow; and
• a fluid channel (149) configured to provide a fluid-based sealing mechanism to prevent blood ingress into critical areas of the impeller apparatus.
wherein,
o each impeller blade (111) has a leading edge (112) and a trailing edge (125);
o each impeller blade (111) has a variable thickness distribution with a maximum thickness location (130) positioned between the leading edge (112) and the trailing edge (125);
o the impeller blades (111) have a first sweep angle (122) at the leading edge (112) and a second sweep angle (123) at the trailing edge (125);
o the impeller blades (111) have a sweep structure at the leading edge and a wrap angle (126) defining degrees by which the blade is wrapped;
o the impeller apparatus exhibits two distinct configurations:
a) a hubbed configuration with a central hub supporting the impeller blades; and
b) a hub-less configuration with the impeller blades arranged circumferentially around a central axis.
2. The impeller apparatus (145) for a catheter-based blood pump as claimed in claim 1, wherein the first sweep angle at leading edge of the impeller blade (122) ranges from -40 degrees to 20 degrees.
3. The impeller apparatus (145) for a catheter-based blood pump as claimed in claim 1, wherein the second sweep angle at trailing edge of the impeller blade (123) ranges from -60 degrees to 0 degrees.
4. The impeller apparatus (45) for a catheter-based blood pump as claimed claim 1, wherein the impeller blades (111) have a wrap angle (126) ranging from 45 degrees to 360 degrees.
5. The impeller apparatus (145) as claimed claim 1, wherein the guide vanes (138) are configured to direct blood flow and convert kinetic energy to pressure energy.
6. The impeller apparatus as claimed in claim 1, wherein in the hubbed configuration, the central hub comprises:
• a dome-shaped structure at an upstream side;
• a middle section transitioning into a truncated cone with an increasing radius; and
• a downstream side with a curved, expanding conical shape and parabolic profile.
7. The impeller apparatus as claimed claim 1, wherein the guide vanes (138) of the flow navigator (146) are twisted in a direction selected from:
• same direction as a flow angle at the impeller blade trailing edge, or
• opposite direction to the flow angle at the impeller blade trailing edge.
8. The impeller apparatus (145) as claimed claim 1, wherein the apparatus comprising a support ring (134) connecting outer edges of the impeller blades (111) in a hub-less configuration.
9. The impeller apparatus (145) as claimed claim 1, wherein the maximum thickness location (130) is positioned at approximately 30-50% of the chord length from the leading edge (112).
10. The impeller apparatus (145) as claimed claim 1, wherein the impeller blades (111) have a leading edge angle (128) and a trailing edge angle (129) configured to optimize blood flow and reduce hemolysis.
11. The impeller apparatus (145) as claimed claim 1, wherein the fluid seal channel (149) that utilizes a microchannel via a hypotube to enable continuous flow of a biocompatible fluid.
12. A method of operating an impeller apparatus (145) for a catheter-based blood pump as claimed in claim 1, the method comprising:
o inserting the catheter-based blood pump through a blood vessel;
o activating a motor (144) to rotate the impeller apparatus (145) at a rotational speed in the range of 10,000 to 60,000 RPM;
o pumping blood through the impeller apparatus (145) to achieve a flow rate in the range of 0 to 6 liters per minute;
o directing blood flow using the flow navigator (146) with guide vanes (138) positioned at angles of 30 to 60 degrees relative to the flow direction; and
o preventing blood ingress into critical areas using the fluid-based sealing mechanism with a fluid pressure of 5 to 15 mm Hg above blood pressure.
13. The method as claimed in claim 11, wherein directing blood flow comprises converting kinetic energy to pressure energy using the guide vanes (138) of the flow navigator (146).