Device for axially conveying body fluids

[0001] The invention relates to a device for axially conveying body fluids.

[0002] In particular, body fluids such as blood which can undergo irreversible changes caused by an energy input, such as in the case of emulsions and dispersions, can run into instable ranges in a disadvantageous manner when being conveyed in corresponding devices such as pumps.

[0003] Blood is a particularly sensitive fluid system. This opaque red body fluid of the vertebrates circulates in a self-enclosed vessel system where rhythmic contractions of the heart press the blood into various areas of the organism. In this case, the blood transports the respiratory gases oxygen and carbon dioxide as well as nutrients, metabolic-products and endogenous active ingredients. The blood vessel system including the heart is hermetically isolated from the environment so that, in a healthy organism, the blood does not undergo any changes when it is pumped through the body by way of the heart.

[0004] It is known that, when blood comes into contact with non-endogenous materials or as a result of the effect of energy from an external source, it has a tendency to hemolysis and clot formation. Clot formation can be fatal for the organism because it can lead to blockage in the extensive branching profile of the vessel system. Hemolysis describes the condition where the red blood cells are destroyed within the body beyond the physiological dimension.

[0005] The causes for hemolysis can be of a mechanical or metabolic nature. Increased hemolysis causes multiple organ damage and can lead to a person's death.

[0006] On the other hand it is evident that it is possible in principle, under certain prerequisites with reference to constructive aspects, to support the pumping capacity of the heart or even to replace the natural heart with a synthetic one. However, a continuous operation of implanted heart supporting systems or synthetic hearts is presently only possible with certain limitations heart supporting systems or synthetic hearts is presently only possible with certain limitations because the interactive effects of these artificial products with the blood and the entire organism still always lead to disadvantageous changes of the blood and the organism.

[0007] In the state of the art, axial blood pumps are known which mainly consist of a cylindrical tube in which a conveying part, which is executed as an externally located motor stator, is located. The rotor which is provided with a so-called blading, conveys the fluid in an axial direction after it has been made to rotate by means of the motor stator.

[0008] In the WO 00/64030 a device for the protective conveying of single- or multiple-phase fluids is described. Where this device is concerned, and in the direction of flow, an inlet guide facility is arranged upstream of the conveying part (rotor) and, as seen in the direction of flow, an inlet guide facility is arranged upstream of the conveying part (rotor) and, as seen in the direction of flow, an outlet guide facility is arranged downstream of the conveying part. Even though the blood in the flow passage zone of the pump does not undergo essentially any disadvantageous changes, the disadvantage is evident to the extent that, in the inflow zone upstream of the inlet guide facility and in the outflow zone downstream of the outlet guide facility of the pump, disrupted flows can form which can lead to a change of the blood.

[0009] In the U.S. Pat. No. 4,994,078 a heart pump is described whose outlet and inlet zones have certain flow cross-sections which are characterised by cross-sectional reductions and expansions, respectively. However, this flow pattern of the blood indicated at that location is only inadequately illustrated so that, in the outflow zone, it is not clearly recognisable how the blood flow is conducted further.

[0010] The invention is based on the task assignment of executing the inflow zone and the outflow zone of an axial pump in such a way that no flow separation occurs with an envisaged deflection of the flow in these zones, but instead a non-disrupted flow profile remains upheld to the greatest extent.

[0011] Therefore, this is the device according to the invention for the axial conveying of body fluids, consisting of a tube-shaped hollow body (1) transporting the liquid in an essentially axial manner, and in this hollow body (1) there is arranged in axial alignment a conveying part that can be rotated by a motor stator (3) located outside of the hollow body (1) in a pump casing (8), where the conveying part (2) has a rotor blading (5) and where stationary inlet and outlet guide facilities (6, 7) are arranged in the direction of flow upstream and downstream of the conveying part (2), and inflow and outflow zones (10, 11) which are positioned at the hollow body (1) in a flow-direction-changing mode, where in the inflow zone (10) an intake bend (12) having an intake bend angle (15) is positioned at the tube-shaped hollow body (1) and in the outflow zone (11) an outlet bend (13) having an outlet bend angle (14) is positioned at the hollow body (1), and where the intake bend (12) has a cross-sectional reduction in the direction of the inlet guide facility (6) and the outlet bend (13) in the direction of flow up to an outlet cylinder (19) has a cross-sectional reduction,

wherein the intake and outlet bends (12, 13) as well as the inlet and outlet channels (17, 18) advantageously consist of flexible material.

[0012] A flow diffuser (25) and an outlet channel (17) are arranged in the direction of flow downstream of the outlet cylinder (19).

[0013] I a further embodiment of the invention, the flexible material essentially consists of silicone and/or reinforced silicone (fabric). The flexibility of the material allows an optimal operative insertion of the device according to the invention as well as its function in the thoracic area.

[0014] In a further embodiment of the invention, the outlet bend and the intake bend only have some individual areas made of flexible material.

[0015] The radius of the intake bend and the diameter of the inlet of the intake bend are in a ratio of 1:2.

[0016] The flow diffuser has a cross-sectional expansion in the direction of flow.

[0017] The formation of the inflow zone and the outflow zone, according to the invention, of a category-related axial pump leads to a situation where the flows can be accelerated very gently without causing disrupted flow regimes. In this case, particularly the formation of the intake bend angle according to the invention, between 45° and 50°, in relation to the change of the flow cross-section, has proved to be very advantageous. The size of the outlet bend angle in this case is between 85° and 95°. The flow profile produced here according to the invention can therefore be characterised by the following advantageous properties:

• • [0018] special form-shaping of the intake bend with permanent acceleration of the flow in the inflow to the inlet guide facility;
  • [0019] optimised inflow to the conveying part by means of a corresponding configuration of the inlet guide facility;
  • [0020] optimised energy transfer in the conveying part;
  • [0021] conditioning of the flow and pressure recovery in the outlet guide facility;
  • [0022] special configuration of the outlet bend with permanent acceleration of the flow in the bent zone;
  • [0023] conditioning of the flow in the area of the connecting piece to the outlet channel, this connecting piece being preferentially provided with a gradual cross-sectional expansion in form of a rotation-symmetrical diffuser. The device according to the invention receives a particularly advantageous embodiment by the selection of elastically adequately form-stable materials, for the intake and outlet bends which can, in this way, accommodate physically-related permanent movements in the area of the connection of the device to the heart chamber (ventricle) and/or to the aorta.

[0028] FIG. 1 shows the schematic illustration of a category-related axial pump with an intake bend 12 and an outlet bend 13. With an intake collar 28, the intake bend 12 is secured to an inflow zone 10 of a cylindrical hollow body 1. With an outlet collar 29, the outlet bend 13 is secured to an outlet flow zone 11 of the cylindrical hollow body 1. As seen in the direction of flow, the cylindrical hollow body contains a stationary inlet guide facility 6 with a guide blading arrangement 9, a floating bearing-located conveying part 2, consisting of a motor rotor 4, a rotor blading arrangement 5 and a back-up ring 30. As seen in the direction of flow, and downstream of the motor rotor 4, a stationary outlet guide facility 7 with an outlet guide blading arrangement 16 is arranged. The motor rotor is caused to rotate by means of a motor stator 3 which is arranged in a pump casing 8. In an axial pump shown here as an example, a flow diffuser 25 is envisaged at the outlet bend 13. By way of an inlet channel 18, the blood to be conveyed enters an inlet cylinder 20 of the intake bend 12 and then, in accordance with the bend routing 24 of the intake bend 12, it is deflected by an intake bend angle 15 in the direction of flow and led into the intake collar 28. The intake bend 12 here and downstream has a permanent cross-sectional narrowing up to the inflow zone 10. The blood is now led via the inlet guide facility 6 and past the motor rotor 4 and by way of the outlet guide facility 7 into the outflow zone 11 of the cylindrical hollow body 1. At this point, the blood enters the outlet collar 29 of the outlet bend 13 and is deflected in the outlet bend 13 in the direction of flow by an outlet bend angle 14. Here again, there is a cross-sectional narrowing of the outlet bend 13. An outlet cylinder 19 of the outlet bend 13 is added here in an exemplary manner at the flow diffuser 25 which has downstream a permanent cross-sectional enlargement in the direction of an outlet channel 17. Based on the arrangement of the intake bend 12 which deflects the blood flow under the intake bend angle 15, and the arrangement of an outlet bend 13 which deflects the blood under the outlet bend angle 14, a non-disrupted flow profile is achieved.

[0029] FIG. 2 shows in a schematic cross-sectional illustration the outlet bend 13 which leads the blood to be conveyed by way of a pump outlet 27, the outlet flow zone 11 and a bend 23 into the outlet cylinder 19 and then further into the flow diffuser 25 and the outlet channel 17. With this routing method of the flow, a separation of the flowing blood from an inner wall 22 of the outlet bend 13 is advantageously avoided.

[0030] The intake bend 12 as shown in FIG. 3 in a schematic sectional arrangement deflects the blood coming from the inlet channel 18 via the inlet cylinder 20 around an intake bend angle 15 into the inlet collar 28. In this case, a permanent cross-sectional narrowing of the intake bend 12 is effected downstream up to the inlet collar 28. By way of the inflow zone 10, the blood is then conveyed into the pump inlet 26. Due to the permanent flow cross-sectional narrowing existing here according to the invention, no separation of the flow from the wall 21 of the intake bend 12 occurs.

• [0031] 1 Hollow body
• [0032] 2 Conveying part
• [0033] 3 Motor stator
• [0034] 4 Motor rotor
• [0035] 5 Rotor blading
• [0036] 6 Inlet guide facility
• [0037] 7 Outlet guide facility
• [0038] 8 Pump casing
• [0039] 9 Guide blading
• [0040] 10 Inflow zone
• [0041] 11 Outflow zone
• [0042] 12 Intake bend
• [0043] 13 Outlet bend
• [0044] 14 Outlet bend angle
• [0045] 15 Intake bend angle
• [0046] 16 Outlet guide blading
• [0047] 17 Outlet channel
• [0048] 18 Inlet channel
• [0049] 19 Outlet cylinder
• [0050] 20 Inlet cylinder
• [0051] 21 Wall
• [0052] 22 Wall
• [0053] 23 Bend
• [0054] 24 Bend
• [0055] 25 Flow diffuser
• [0056] 26 Pump inlet
• [0057] 27 Pump outlet
• [0058] 28 Inlet collar
• [0059] 29 Outlet collar
• [0060] 30 Back-up ring