Blood pump

Abstract

To provide a blood pump in which a pump housing, a shaft arrangement and a delivery element are adapted to one another such that they guarantee the best possible efficiency and durability of the pump.SOLUTION: A blood pump 1 includes a proximal end, a distal end, a pump housing 2 arranged therebetween, a drive shaft 4 and a delivery element 5. The delivery element 5 includes at least one foldable segment.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention lies in the fields of mechanics, precision mechanics, and materials technology, and relates to pumps or pump assemblies, in particular, blood pumps.

Background Art

[0002] In the prior art, pumps are known that have a proximal end and a distal end, and a pump housing disposed therebetween, a drive shaft disposed inside the pump housing along the longitudinal direction, a conveying element disposed on the drive shaft, and a cannula or catheter disposed proximal to the pump housing. This type of pump often has a flexible drive shaft and can be guided even in difficult-to-access locations so that the pump can implement the pumping effect there. One example is a blood pump, which is inserted, for example, through the femoral artery through the aortic arch into the left ventricle of the heart and remains in the region of the aortic valve. At the proximal end of the pump, i.e., at the end of the drive shaft that remains, for example, disposed outside the body, the pump can be connected to a motor, which drives the drive shaft and, thus, the conveying element disposed on the drive shaft, where the pump is disposed, for example, in the left ventricle. Thus, blood can be pumped from the ventricle to the aorta.

[0003] In such pumps, it is known that the pump housing is formed such that, under the application of a force acting on the proximal end of the pump, the pump housing can be at least partially moved into the cannula or catheter. In other words, for example, by the application of a tensile force in the region of the proximal end of the drive shaft, the pump housing can be drawn into the cannula and thus can be taken from an expanded state with a larger radial spread to a compressed state with a smaller radial spread. This shift is provided, inter alia, before the insertion of the pump into the body and the removal of the pump from the body. The reason is that the reduced diameter of the pump housing facilitates the navigation of the distal end of the pump within the human body and, in particular, ensures a minimally invasive passage through the skin. Here, the pump housing is usually made of a metal, for example, a shape memory metal. Further materials can be used for the pump housing provided that they withstand the mechanical stresses during compression and expansion and meet medical hygiene standards.

[0004] In the case of this type of pump, it is also common for a conveying element, such as a rotor, to include at least one foldable or flexible segment, for example in the form of rotor blades. An example of this type of rotor is described, for example, in US Patent Application No. 13 / 261,565, the disclosure of which is incorporated herein by reference in its entirety. Moreover, US Patent Application No. 13 / 261,100 is similarly incorporated herein by reference in its entirety.

[0005] With regard to the pump housing, by way of example, US Patent Application No. 13 / 146,452 is referred to, which is similarly incorporated herein by reference in its entirety. Also, US Patent Application No. 13 / 261,256 is referred to, which is similarly incorporated herein by reference in its entirety.

[0006] When designing the pump housing, it has been proven that in the expanded state of the pump housing, a portion that wraps around this longitudinal axis can be generated in a spiral pattern around the longitudinal axis that extends along the drive shaft, when considered from the proximal end to the distal end of the pump. However, here, it should not be understood that a structure extending in a spiral or helical pattern, in particular a spiral or helical strut, must completely surround the longitudinal axis. It is also understood to mean a part of the spiral that forms a segment of the spiral around the longitudinal axis, i.e., a curved strut that substantially follows the course of the spiral around the longitudinal axis over a portion can also be referred to.

[0007] By the development of this type of pump, the inventors have confirmed that the advantageous cooperation between the pump housing, the drive shaft, and the conveying element helps to produce an efficient blood pump that can be transplanted over a relatively long period.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Summary of the Invention

Means for Solving the Problems

[0009] This object is achieved by a blood pump according to the features of claim 1.

[0010] According to a first reference example of the present invention, when the pump housing is moved from an expanded state to a compressed state, a plurality of structures extending in a spiral shape, or a structure (singular) extending in a spiral shape, are formed so that a torque directed opposite to the first direction acts on the foldable segment. Here, in the present application, it should be stated that a torque acting in the clockwise or counterclockwise direction is frequently referred to. More specifically, here, instead of referring to the torque, the direction of the force generating the torque is referred to. Torque is the vector product of the radial position vector directed outward from the longitudinal axis and the vector of the generated force, and thus extends in a direction perpendicular to the generated force. In other words, when a torque extending in the clockwise direction is referred to, this rather means a torque extending parallel to the longitudinal axis. However, for the sake of simplified and improved orientation, the direction of the torque is often identified with the direction of the generated force, although this does not correspond to the physical definition.

[0011] The portion including the structure extending in a spiral shape preferably forms only a limited portion of the pump housing. This portion causes a torque to develop when the pump housing is drawn into the cannula, and the torque is directed opposite to the direction of the spiral winding. Due to its shape and its flexible or foldable segments, the rotor has a tendency to wind around the drive shaft in a specific direction when the housing is compressed. Since the torque is created when the housing is compressed, this similarly acts on the foldable segment and can thus, for example, prompt the foldable segment to fold in a pre-determined folding direction with respect to it.

[0012] This means that the torque applied by the pump housing assists the natural folding of the flexible segment around the drive shaft and thus counteracts damage to the rotor.

[0013] In the first reference example, a foldable segment of the conveying element is formed such that the torque in the rotational direction of the conveying element corresponds to the conveyance of fluid from the distal end portion to the proximal end portion of the pump. In other words, when the fluid is conveyed from the distal end portion to the proximal end portion of the pump and a flexible segment of the conveying element is formed accordingly, the first direction in which the helical structure extends is opposite to the rotation of the conveying element during operation. Surprisingly, both an improvement in the efficiency of the pump as a result and a reduction in potential damage to the pump housing were found.

[0014] In a further reference example, a foldable segment of the conveying element is generated such that the torque is directed to the side opposite to the rotational direction of the conveying element. In addition, the deployment direction of at least one foldable segment during deployment extends in the first direction. This means that the rotational direction of the conveying element when conveying fluid from the distal end portion to the proximal end portion is directed to the side opposite to the deployment direction of the rotor.

[0015] In a further reference example, a foldable segment of the conveying element can be formed such that the torque is directed to the side opposite to the rotational direction of the conveying element in order to convey fluid from the distal end portion to the proximal end portion of the pump.

[0016] In a further reference example, the deployment direction of at least one foldable segment during deployment is in a direction opposite to the first direction.

[0017] In a further reference example, the pump housing is made of a shape memory material. Here, the pump housing can be manufactured, for example, from nitinol.

[0018] In a further reference example, the "austenite finish" (A f) The temperature is lower than a healthy human body temperature, and in particular, lower than 30°C, and in particular, lower than room temperature, that is, lower than 20°C. Surprisingly, it has been found that at this A f temperature, the stability and lifespan of the housing can be improved. This is especially true when A f the temperature is lower than room temperature.

[0019] In a further reference example, the pump housing includes a pump receiving portion and a proximal portion disposed proximal to the pump receiving portion. The inner diameter of the proximal portion is reduced from the diameter of the pump receiving portion to the proximal end of the proximal portion in the expanded state of the pump housing. With this type of pump housing, drawing into the cannula is facilitated and assisted due to the form of the pump housing. Here, a modified example of the pump according to the present invention is provided, and a helical structure is disposed in the proximal portion.

[0020] In an alternative reference example, the helical structure is disposed in the pump receiving portion. In a further reference example, the helical structure is disposed in both the proximal portion and the pump receiving portion.

[0021] In a further reference example, the pump housing includes a further distal portion disposed distal to the pump receiving portion. The inner diameter of the further distal portion is preferably reduced from the diameter of the pump receiving portion to the distal end of the distal portion in the expanded state of the pump housing.

[0022] Thus, the drive shaft can be supported by a further bearing, for example, in the region of the reduced inner diameter of the distal portion, enabling improved protection of the rotor.

[0023] In an embodiment, the helical structure is also disposed at the distal portion. Here, the helical structure can be wound or wound in the opposite direction of the first direction. In this embodiment, the helical structure assists in the formation of torque at both the proximal and distal portions, and the formation of the torque is initiated across the entire pump housing between the proximal and distal portions, but the torque causes only the deflection or torsion of the helical elements in the regions of the proximal and distal portions. In a variant, the helical structure in the proximal and distal regions is formed such that the torque is directed in the same direction proximally and distally and / or the proximal torque and the distal torque are of the same magnitude. This is analogous and equivalent to the wrapping of a lollipop in a lollipop wrapper, where the lollipop can be unwrapped from the wrapper by holding both ends and pulling simultaneously. Thus, by way of example, the drive shaft is prevented from twisting and is thus protected against damage.

[0024] In a further reference example, the drive shaft is alternatively or additionally pivotally supported in the region of the proximal end of the pump housing.

[0025] The blood pump of the present invention includes a proximal end portion and a distal end portion, and a pump housing disposed therebetween, a drive shaft disposed inside the pump housing along the longitudinal direction, and a conveying element disposed on the drive shaft. The conveying element includes at least one flexible segment, and the at least one flexible segment is formed such that the rotation direction of the conveying element causes fluid to be conveyed from the distal end portion to the proximal end portion of the blood pump. The pump housing is formed such that under the application of a force acting on the proximal end portion of the blood pump, the pump housing can be at least partially moved into the cannula. When the pump housing is at least partially moved into the cannula, it is moved from an expandable state to a compressed state at least along a radial direction extending in a transverse direction with respect to the longitudinal direction. When the pump housing is withdrawn from the cannula and moved from the compressed state to the expanded state, the deployment direction of the at least one flexible segment is oriented opposite to the rotation direction. The conveying element is formed by integrally molding plastic. The pump housing has helical struts at the proximal portion and the distal portion, and lattice-shaped struts between the proximal portion and the distal portion. The deployment direction of the at least one flexible segment is in the same direction as the spiral direction of the struts. That is, in an aspect of the present invention, when the pump housing is moved from a compressed state to an expanded state, the deployment direction of the at least one flexible element is provided opposite to the rotation direction of the conveying element when fluid is conveyed from the distal end portion to the proximal end portion of the pump, regardless of the helical structure. In this case, similar to the first aspect of the present invention, it should be understood that the movement of the outer end portion of the segment of the conveying element means the deployment direction when considered in the radial direction.

[0026] The blood pump of the reference example is a blood pump having a pump housing, a drive shaft disposed inside the pump housing along a longitudinal axis, and a conveying element disposed on the drive shaft, wherein the pump housing includes at least one pump receiving portion and one proximal portion disposed proximal to the pump receiving portion, the pump housing can be moved from a compressed state to an expanded state in a radial direction extending transversely to the longitudinal direction, the drive shaft is pivotally supported by a proximal bearing in a region of the proximal portion of the pump housing, and the drive shaft is configured such that the stiffness and flexibility of the region of the proximal portion of the pump housing and the drive shaft distal to the proximal bearing are adjusted to the stiffness and flexibility of the proximal portion, and when the pump housing bends, the conveying element is substantially concentrically disposed in the pump receiving portion. That is, the aspect of this reference example includes a pump housing, a drive shaft disposed inside the pump housing along a longitudinal axis, and a conveying element disposed on the drive shaft. The pump housing includes at least one pump receiving portion and one proximal portion disposed proximal to the pump receiving portion, and the pump housing can be moved from a compressed state to an expanded state in a radial direction extending transversely to the longitudinal direction. The drive shaft is pivotally supported by a proximal bearing in a region of the proximal end of the pump housing.

[0027] In the reference example, the drive shaft is configured such that the stiffness flexibility of the drive shaft in the region of the proximal portion of the pump housing and the stiffness flexibility of the drive shaft distal to the proximal bearing correspond to the stiffness flexibility of the proximal portion of the pump housing. Thus, in any case of bending, the pump housing and the conveying element are mounted / axially supported substantially concentrically with each other within the pump receiving portion. In other words, the bending line of the pump housing in the proximal portion is coordinated with the bending line of the flexible shaft in the region of the proximal portion, and the bending moment acting on the distal end portion of the pump housing is such as to induce similar bending in both the housing and the shaft. Therefore, the rotor is prevented from colliding with the pump housing due to different resistances to bending, and damage to the pump housing or the rotor itself is also prevented. During the operation of the pump, the pulsating movement of the beating heart or the movement of the patient may result in a bending moment or force, which, without adjustment of the resistance to bending or the bending moment, may lead to damage to the rotor or the pump housing.

[0028] In the modified example, the stiffness flexibility of the proximal portion of the pump housing is softer compared to the pump receiving portion. In the region of the proximal portion, the flexible shaft is also softer compared to the shaft portion in the pump receiving portion of the housing.

[0029] The stiffness flexibility of the pump housing in the proximal part can be affected, for example, by a helical structure. Due to the helical structure, in one exemplary embodiment, an elastic region is generated that blocks mechanically alternately applied loads due to different acting bending moments. Here, according to a modification, the helical structure will be arranged symmetrically around the longitudinal axis. The helical structure thus forms a helical region with a spring effect. This spring effect enables control of the desired stiffness flexibility. In particular, the desired stiffness flexibility can be set via the angle or spiral course of the helical structure. To ensure the fatigue strength of the pump housing, the maximum local strain at any point of the pump housing is less than 2% in the modification.

[0030] In a further embodiment, the pump housing also includes a distal part that is distal to the pump receiving part, the drive shaft is pivotally supported in a distal bearing in the region of the distal end of the pump housing, and the stiffness flexibility of the region of the distal part and the drive shaft proximal to the distal part is adjusted to the stiffness flexibility of the distal part so that when the pump housing bends, the conveying element is arranged substantially concentrically in the pump receiving part. Here, the drive shaft can be additionally pivotally supported, for example, in the region of the distal end of the pump, and the drive shaft is fixed between the proximal bearing and the distal bearing. Since the drive shaft has a stiffness flexibility corresponding to the stiffness flexibility of the pump housing in the proximal part or the distal part in the regions of the distal part and the proximal part of the pump housing, it is possible to ensure that a rotor is mounted substantially concentrically in the pump housing.

[0031] In a further embodiment, for example, at the distal or proximal end of the pump region, the pump housing is formed such that its stiffness is adjusted to that of the catheter. If the catheter is too stiff, strong deformations are introduced into the pump housing, but if the catheter is too soft, the position of the housing during operation is not fixed, and in either case, reliable operation of the rotor within the pump housing cannot be ensured. By adjusting the stiffness of the pump housing to that of the catheter, concentric mounting of the rotor within the pump receiving portion is ensured here even during operation of the pump.

[0032] To affect the stiffness of the shaft, a hollow shaft can be used, and in particular, a core is provided in the region of the pump receiving portion. In addition, the core can extend to the distal and proximal bearings. Also, in the pump of an aspect of the present invention, the "austenite finish" (A f ) temperature of the pump housing can be lower than 34 °C, further lower than 30 °C, and even lower than 20 °C.

[0033] In the pump configuration described in this application, different external force effects and alternating bending loads actually act on the drive shaft, the pump housing, the pigtail located distally of the pump housing, and, where applicable, the bearing elements of the catheter or the blood pump configuration. The pulsating pressure changes or flow rate changes of the blood in the heart chambers or blood vessels, such as the left ventricle or right ventricle or aorta, and / or the changes in the body position or posture, in particular the movement of the torso or (leg) movement in the vicinity of the puncture site, can transfer the external force effects and alternating bending loads to the catheter, for example, by the inner wall of the heart. The catheter can abut or be supported against the inner wall of the heart (for example, via what is known as the pigtail tip). Despite these loads, the blood can be conveyed by the proposed catheter and the proposed blood pump configuration for a relatively long period of time, for example, at a high rotational speed of the pump rotor within the above-described rotational speed range, for example, for several hours, days, or weeks.

[0034] It is noted that the features specified in each reference example can also be combined with the invention according to claim 1.

[0035] A further aspect will be described based on the following figures.

Brief Description of the Drawings

[0036]

Figure 1

Figure 2a

Figure 2b

Figure 2c

Figure 2d

Figure 3a

Figure 3b

Figure 3c

Figure 3d

Figure 4a

Figure 4b

Figure 5a

Figure 5b

Figure 6a

Figure 6b

Figure 7a

Figure 7b

Figure 7c

Figure 8

Figure 9

Best Mode for Carrying Out the Invention

[0037] A schematic overview of the pump assembly 1 is provided based on FIG. 1. The pump assembly 1 includes a pump housing 2 with a cannula or catheter 3, and a drive shaft 4 is disposed within the cannula or catheter 3. A transport element 5 is driven via the drive shaft 4, and a motor 6 is attached to the proximal end of the drive shaft. The transport element 5 is positioned within the region of the pump housing 2. The pump including the drive shaft 4 is here introduced into the ventricle 10, for example, through the femoral artery 8 and the aortic arch 9 via a port 7, such that the pump housing is located within the region of the aortic valve. Here, the rotor 5 is formed such that blood is transported in direction 12 from the ventricle into the aorta, i.e., from the distal end of the pump to the proximal end of the pump.

[0038] Various interactions between the housing, the drive shaft, the transport element, and the cannula will be explained based on FIGS. 2a to 2d. In FIGS. 2a and 2c, the pump housing 20 is illustrated in longitudinal section in an expanded state (FIG. 2a) and a compressed state (FIG. 2c). Corresponding cross-sections can be found in FIGS. 2b and 2d.

[0039] The drive shaft 21 is disposed within the pump housing 20, and the conveying element 22 is positioned on the drive shaft. In this example, the conveying element includes two flexible segments 23 and 24, and the two flexible segments 23 and 24 are embodied as rotor blades. The pump housing 20 moves from an expanded state to a compressed state by pulling the drive shaft in the pulling direction 25, and the pulling direction 25 is parallel to the longitudinal direction 26 of the pump housing. The cross-section is illustrated in FIG. 2b with respect to the illustration of the pump housing in the explanatory drawing of FIG. 2a. It can be seen that the pump housing 20 is disposed substantially concentrically around the drive shaft 21. In the cross-section illustrated here, a strut 27 extending helically as a helical structure is seen, and the strut 27 can be widened in the radial direction 27a from the proximal portion to the distal portion. The strut extends counterclockwise from the proximal end of the pump housing 28 to the distal end of the pump housing 29. By comparison, the conveying element 22 is also shown, and the flexible segments of the conveying element 22 convey fluid. Also, this can be seen in the plan view of FIG. 2a. As an alternative to the various struts, another helical structure can be selected. It is, for example, various struts that form the line or structure of the helix for their arrangement and the like.

[0040] When the pump housing 20 is pulled in the pulling direction 25 and thus drawn into the cannula 30 from the expanded state shown in Fig. 2a to the compressed state, the helical element creates a torque 31, which acts in the clockwise direction. Thus, it is opposite to the course of the helical struts and attempts to counter the twist of the helical struts, but no visible change in the housing can be recognized. As a result of the torque, segments 23 and 24 are acted upon such that, as shown in Fig. 2d, they wind around the drive shaft 21 in the folding direction 32 by the torque 31. Thus, when the pump housing slides out longitudinally from the cannula 30 in the deployment direction 33, the rotor unfolds.

[0041] In the example illustrated here, the subsequent rotational direction of the rotor is the rotational direction 34, which is opposite to the deployment direction. In particular, it can be provided as a result that the rotor is further deployed at a higher rotational speed. However, in other variants, it is possible to select the rotational direction to coincide with the deployment direction. Here, a higher rotational speed causes an easy folding of the rotor in the folding direction 32.

[0042] In this example, the drive shaft is made of a nickel-cobalt alloy such as 35NL T (registered trademark) or MP35N (registered trademark). For example, the cannula is formed from a catheter made of a material known from the prior art such as silicone or polyurethane. The pump housing can be made, for example, from nitinol. Here, in this example, the A f temperature of the pump housing is approximately 15 °C and the A f temperature is below room temperature. This has advantages from the perspective of the stability of the pump housing. In the following example, the drive shaft is simply supported by the proximal bearing sleeve 35. Regarding the material used for the rotor, for example, the materials described in US Patent Application No. 13 / 261565 can be used.

[0043] In the example illustrated in FIG. 2, the struts arranged in a spiral extend into both the proximal portion of the pump housing and the region of the pump receiving portion. The proximal portion of the pump housing is located proximal to the conveying element 22, and the region of the pump receiving portion is located within the region of the conveying element 22.

[0044] Variations of the combination of the pump housing, the conveying element, and the drive shaft are shown by way of example in FIGS. 3a to 3d.

[0045] The difference between the embodiment of FIG. 2 and the embodiment of FIG. 3 is, inter alia, that the drive shaft in the embodiment of FIG. 3 is pivotally supported both in the distal end and in the region of the proximal end of the pump housing.

[0046] The pump housing 40 shown in FIG. 3a includes a pump receiving portion 41, a portion 42 disposed distally of the pump receiving portion, and a distal end portion 43 disposed distally of the distal portion. The pump housing also includes a proximal portion 44 disposed proximally of the pump receiving portion and an end portion 45 disposed proximally of the proximal portion. The pump housing 40 has helical struts 46 in the proximal portion 44 and the distal portion 42, as shown, for example, in FIG. 3b. Here, the struts extend in a counterclockwise direction from the proximal end of the pump to the distal end of the pump. The cannula 47 is additionally shown in FIG. 3a, and the cannula encloses the drive shaft 48 as it passes through the aortic arch and the blood vessels of the body. A rotor 49 is additionally disposed on the drive shaft in the region of the pump receiving portion 41 of the housing and serves to convey blood from the distal end to the proximal end. Based on FIG. 3b, it can be seen that the helical strut 46 extends in the proximal portion 44 in a counterclockwise direction from the inside (i.e., the distal end of the end portion 45) to the outside (i.e., toward the proximal end of the portion 41), while the helical strut 50 in the distal portion 42 extends in a clockwise direction from the outside to the inside. As a result, when the distal end portion 43 and the proximal end portion 45 are grasped at both portions and pulled in opposite directions, a torque extending in the clockwise direction acts on the pump receiving portion 41. Also, this mechanism is effective when the pump housing is drawn into the cannula. In a manner corresponding to FIG. 2a, the pump of FIG. 3a is shown in an inflated state. Here, when a tensile force 53 directed opposite to the longitudinal direction 52 becomes effective, the diameter of the pump housing is reduced, on the one hand, in the portions 41, 42, and 44, and at the same time, a torque 51 acting in the clockwise direction is induced. Due to the reduction in diameter during collapse, the pump housing 40 interacts with the conveying element 49 or the flexible segments 54 and 55 of the conveying element 49. Due to their shape and their orientation, the flexible segments 54 and 55 have a folding direction 56 in the direction of the torque.Thus, the flexible segments 54 and 55 are wound in the folding direction 56 around the drive shaft 48. Here, when the pump housing is moved from the compressed configuration of FIG. 3c to the expanded configuration of FIG. 3a, the rotor expands in the deployment direction 57, which coincides with the spiral direction 58 of the helical struts. In this example, the rotor 48 then rotates in the direction 59 to guide blood from the distal end to the proximal end of the pump.

[0047] The embodiment shown in FIG. 3 corresponds to a “candy wrapper”. The reason is that the spirals defining the courses of the helical struts rotate in opposite directions in the distal and proximal portions. As a result, torque is simply introduced into the pump receiving portion 41 in the distal portion 42 and the proximal portion 44, however, the torque acting in the distal end portion 43 and the proximal end portion 45 is reduced. Since bearings (not shown) for the drive shaft 48 are positioned in the distal end portion and the proximal end portion, when the pump housing 40 is moved from the expanded state to the compressed state, the torque of the pump housing is transmitted to the drive shaft as necessary.

[0048] Aspects of the corresponding stiffness and flexibility of the pump housing and the corresponding stiffness and flexibility of the shaft will be discussed based on FIGS. 4a and 4b, and also based on FIGS. 5a and 5b.

[0049] A pump structure corresponding to that of FIG. 3 is illustrated in FIGS. 4a and 4b. In particular, the pump housing 40 includes the portions 41 to 45 described with reference to FIG. 3, and a drive shaft 48, which is held proximally at a first bearing 60 and also held at a distal bearing 61. The helical struts 46 and 50 are disposed in the distal portion 42 and the proximal portion 44, respectively. Here, as illustrated in FIG. 4b, when a bending moment is applied to the pump housing 40, the helical struts 46 and 50, due to their symmetrical arrangement around the drive shaft, cause the pump housing to bend, in particular, and the bending corresponds to the corresponding bending of the drive shaft in the distal portion 42 and the proximal portion 44, respectively. Here, the shaft can be softer, for example, in the region described above, than in the region of the pump receiving portion 41. The hardening in the pump receiving portion is additionally strengthened by the rotor itself or the rotor hub. As a result, as can be seen in FIG. 4b, the conveying element 49 remains substantially concentric within the pump receiving portion even under a bending load. As an example, for the thickness of the struts, the selected angle of the helical struts, as well as the number and arrangement of the struts, the corresponding bending moment can be adapted to the stiffness and flexibility of the shaft in the corresponding region. Here, the bending moment is the sum of the products of the generated forces and the corresponding force arms over all acting forces. Here, the force arm is the distance from the bearing point. As an example, a point in the region of the proximal bearing can be selected as the bearing point.

[0050] In FIGS. 5a and 5b, corresponding situations are illustrated, where the pump assembly substantially corresponds to the pump assembly of FIG. 2. However, in this case, the pump housing 20' has a rigid pump receiving portion and a distal portion 201 disposed distally of the pump receiving portion 200, and the distal portion has a helical structure 27. The helical structure 27 can be generated for the conductor-like arrangement of various struts and their connections, or by the rotation of segments of the strut structure, and the helical structure 27 is configured such that the stiffness-flexibility of the pump housing at the distal portion 201 is softer than that at the pump receiving portion 202. Thus, the bending moment acting on the pigtail 36 can be absorbed not only by the distal transition structure 37 but also by the distal portion, which can be constructed, for example, from four struts. Thus, the bending moment 38 (FIG. 5b) does not act on the pump receiving portion, and the drive shaft is substantially concentrically located within the pump receiving portion even when a bending moment is applied. The pump receiving portion 200 is more rigid, and measures for increasing the stiffness-flexibility will be described in one of the following exemplary embodiments.

[0051] Also, the pump housing can optionally include a proximal portion 202 having a helical structure 27, and is adapted to compensate for the effective bending moment and to facilitate compression of the pump housing.

[0052] Further details of various aspects of the present invention will be discussed based on FIGS. 6a and 6b. The shaft assembly 70 includes a drive shaft 71 having a distal end 72, a conveying element 73, and a proximal end 74, which can be coupled to a motor, for example, using a coupling element. In the region of the conveying element 73, the drive shaft 71 is reinforced by a core 75 that extends between the distal end 72 and a region proximal to the conveying element 73. The conveying element 73 includes two flexible segments 76 and 77, which cause fluid to be conveyed from the distal end to the proximal end when considering the rotational direction of the conveying element to be clockwise when moving from the proximal end to the distal end. In FIG. 6b, a cross-section of the rotor 73 from the proximal end to the distal end is shown. Here, the form of the flexible segments 76 and 77 can be seen in more detail. The folding direction of the rotor when the pump housing (not shown) is drawn into the cannula is clockwise, that is, points 78 and 79 are transported radially inwards and clockwise. Thus, the rotor unfolds when the conveying element is slid out of the catheter in the counterclockwise direction. Thus, in a variant, the illustrated conveying element or shaft assembly 70 is provided with a housing that is formed such that it creates a torque in the clockwise direction when the pump housing is moved from an inflated state to a compressed state.

[0053] Here, the core 75 can create improved rigidity compared to other regions of the hollow drive shaft 71. Here, the core can have different rigidities from its distal end to its proximal end, for example, such that the proximal and / or distal stiffness of the conveying element is reduced compared to the rigidity of the core in the region of the conveying element. However, the corresponding rigidity of the shaft in the region of the conveying element can also be achieved by the corresponding design (or adjustment) of the rotor hub.

[0054] Further details of the pump housing will be described with reference to FIGS. 7a through 7c. In FIG. 7a, the pump housing shown in FIG. 7b is cut along an imaginary separation line, unrolled from its coiled state, and flattened. However, in one embodiment, the pump housing is first incised, for example, by a laser, as shown in FIG. 7a. Here, the incision can be performed within the tube mold. Next, the configuration shown in FIG. 7b is provided by an annealing process within the mold. The pump housing 80, which is similarly unrolled in FIG. 7a, has a proximal end portion 83 at its proximal end 81, and the proximal end portion 83 extends to the helical element 82. Here, short regions before and after the helical strut 82 define the proximal portion 84. The pump receiving portion 85 has a lattice design in which struts interconnected in a lattice shape have junctions with each other. Similar to the proximal portion 84, the distal portion 86 has a helical strut 87, which is clearly oriented towards the strut 82 from the perspective of their spiral direction. At the distal end, a distal end portion 88 is provided, and in the region of the distal end portion 88, for example, a drive shaft can be pivotally supported within a catheter or pigtail. The angle at which the helical element 82 extends from the proximal end portion to the pump receiving portion can be, for example, between 20° and 40°. Similarly, the angle of the strut 87 can also be 20° to 40° (however, in the opposite direction).

[0055] In those embodiments, two angles are directed in opposite directions as shown in FIG. 7. Here, when the pump housing 80 is joined as shown above, an inflated pump housing as shown in FIG. 7b is created. It can be clearly seen that there is an increase in the inner diameter from the proximal end to the distal end in the regions of the proximal portion 84 and the distal portion 86, respectively, and vice versa. Here, the pump receiving portion 85 has the largest inner diameter in order to achieve high efficiency when conveying fluid. The cross-section of the pump housing 80 when considered from the proximal end to the distal end is shown in FIG. 7c, and it can be clearly seen that the support strut 82 runs in a counterclockwise direction. Also, a support strut 89 is shown, transitioning to the lattice strut 85a of the pump receiving portion.

[0056] The distal end portion 88 of the pump housing 80 is illustrated based on FIG. 8. Here, a catheter 90 is inserted into the distal end portion 88, and in particular, includes a bearing sleeve 91, and the distal end of the shaft assembly 70 is pivotally supported within the bearing sleeve 91. Here, the bearing can be composed of, for example, ceramic, while the shaft can be constructed from the materials described previously.

[0057] In FIG. 9, a longitudinal section through the pump assembly 100 is shown, and the pump assembly 100 includes a pump housing 101, a drive shaft 102, and a rotor 103 disposed on the drive shaft. Also, an outflow tube 104 is shown. In the distal end region 110 of the pump housing, this is connected to a catheter formed as a pigtail (not shown). Here, the attachment of the drive shaft 102 at the distal end portion substantially corresponds to the attachment described based on FIG. 8.

[0058] In the region of the proximal end portion 111, a proximal bearing / axial support 112 of the drive shaft is provided, which includes both a radial bearing and an axial bearing. This bearing is described in more detail in Patent Document 1 (European Patent Application Publication No. 2868289A1, having an internal file reference number 137EP 2457). That application is fully incorporated herein.

[0059] Between the distal end portion and the proximal end portion of the pump housing 101, a distal portion 112, a pump receiving portion 113, and a proximal portion 114 are provided. Here, both the distal portion and the proximal portion each have helical struts 115 and 116, and the helical struts 115 and 116 transition towards the pump receiving portion into support struts 117 and 118 respectively. These support struts are each further divided into the struts 119 of the pump receiving portion. Inside the pump receiving portion, a plastic film 120 is positioned, and in an exemplary embodiment, the plastic film 120 is made from polyurethane. This film improves the conveying effect of the rotor 103.

[0060] The rotor 103 includes two flexible rotor blades 130 and 131, and the two flexible rotor blades 130 and 131 are fastened to a hub 132. In some exemplary embodiments, the rotor is a single workpiece made from a plastic such as polyurethane, for example biresin, or silicone or Pebax. For clarity, the rotor 103 is not shown in an explanatory drawing of a longitudinal section.

[0061] The rotor 103 is disposed on the drive shaft 102, and the drive shaft 102 is formed as a hollow shaft. For further details, reference is made to Application PMP Ref. 137EP 2457. The hollow shaft is reinforced by a core 105 between the distal bearing / axial support and the proximal bearing / axial support.

[0062] When adjusting the bending line of the pump housing to the bending line of the drive shaft, if a bending moment 140 (or 141 or 142) acts on the pump housing, it should be ensured that the rotor 103 remains substantially concentric within the pump receiving portion 113, or that the rotor does not contact the inner surface of the pump receiving portion 113. As a first measure, the stiffness flexibility of the pump receiving portion is higher in stiffness than that of the distal or proximal portion in this exemplary embodiment. For simplicity, the stiffness flexibility of the distal and proximal portions is symmetrically selected in the exemplary embodiment shown. The factors that can affect the stiffness flexibility in the pump receiving portion 113 are constituted by the density and number of the struts 119 in relation to the possible diameter of the housing. In this example, the distal portion 112 and the proximal portion 114 each have 10 helical struts, which each transition into 20 support struts 117 and 118 towards the pump receiving portion. The support struts 117 and 118 are further divided into 40 struts 119, and the number of struts in the pump receiving region is here 4 times larger. In other exemplary embodiments, this multiple can vary between 0.9 and 20. The stiffness flexibility in the pump receiving portion is thus greater than that of the distal or proximal region.

[0063] A further possibility for matching (here, making softer) the stiffness flexibility of the distal and proximal portions compared to the pump receiving portion is constituted by changes in the geometric dimensions of the struts 115 - 119. In this example, the struts 115 and 116 are 2 to 3 times thicker than the struts 119. Due to the multiple of 4 in the ratio of the number of struts, the proximal and distal portions would, in some exemplary embodiments, become too soft if the struts 115 - 119 were of equal thickness, or else.

[0064] A further possibility for matching the stiffness in the regions of the proximal and distal portions is constituted by the choice of the bending angle of the helical struts. In this example, the helical struts are wound at an angle of approximately 30° from the distal end to the proximal end of the proximal or distal portion. However, the range may also be present in the range of 5° to 90°.

[0065] A further possibility is to vary the lengths of the proximal and distal portions. In a method for matching the stiffness of the pump housing, the shaft assembly is first measured, then the above-mentioned parameters of the different portions of the pump housing are calculated, and then an appropriate pump housing is created.

[0066] The stiffness of the drive shaft can be matched by the hollow shaft stiffness, the core stiffness, and the rotor stiffness. In some exemplary embodiments, since the hollow shaft can be exposed to strong curvatures, for example, in the aortic arch, the hollow shaft must have a stiffness that allows this type of curvature while having a strength that allows it to operate as long as possible at a high rotational speed. Thus, in some exemplary embodiments, the stiffness of the hollow shaft is mainly adapted to the requirements of the hollow shaft between the motor and the bearing. However, the core stiffness can also be adapted to match the bending line of the drive shaft to the stiffness of the pump housing between the proximal and distal bearings.

[0067] Moreover, the material selection and geometry of the rotor 103 cause hardening of the drive shaft in the region of the pump receiving portion 113, such that the drive shaft assembly with the rotor is softer in the regions of the distal and proximal portions than in the region of the pump receiving portion. Further possibilities for adaptation will become apparent to those skilled in the art from the comments made here.

[0068] In a further exemplary embodiment, the pump housing has a helical structure, which results from a plurality of interconnected struts. Due to the selection of the connection points between two struts, the struts extend upwardly or downwardly at an incline, creating a helical structure that is oriented in one direction. By varying the thickness, number, and length of the structure, as well as by varying the angle of the included structures, the stiffness flexibility of this structure can be matched to that of the drive shaft.

[0069] Further embodiments and variations of the present invention will arise from combinations specifically identified herein and from combinations that will be apparent to those skilled in the art.

Claims

1. A blood pump (1) having a proximal end portion and a distal end portion, and a pump housing disposed therebetween, a drive shaft disposed inside the pump housing along a longitudinal direction, a conveying element disposed on the drive shaft, and a cannula, wherein the pump housing includes a pump receiving portion, a proximal portion disposed proximal to the pump receiving portion, and a distal portion disposed distal to the pump receiving portion, and is formed to be moved from a radially expanded state to a compressed state when inserted into the cannula, the proximal portion and the distal portion each include a plurality of helical structures that extend helically around the longitudinal axis along the longitudinal axis in the expanded state, each of the helical structures of the proximal portion is wound in a first direction when considered from the proximal end portion to the distal end portion, each of the helical structures of the distal portion is wound in a direction opposite to the first direction, characterized by a blood pump.

2. The blood pump according to claim 1, wherein the conveying element includes at least one foldable segment, characterized in that a deployment direction of the at least one foldable segment extends in the first direction during deployment.

3. The blood pump according to claim 1, wherein the conveying element includes at least one foldable segment, characterized in that a deployment direction of the at least one foldable segment extends in a direction opposite to the first direction during deployment.

4. The blood pump according to any one of claims 1 to 3, wherein the pump housing is made of a shape memory material.

5. The blood pump according to any one of claims 1 to 4, wherein an inner diameter of the proximal portion of the pump housing is reduced from a diameter of the pump receiving portion toward the proximal end portion of the proximal portion in the expanded state of the pump housing.

6. The blood pump according to claim 1, wherein a plurality of the helical structures are disposed in the pump receiving portion.

7. The blood pump according to claim 5, wherein the inner diameter of the distal portion of the pump housing is reduced from the diameter of the pump receiving portion toward the distal end of the distal portion in the expanded state of the pump housing. A blood pump characterized by that. **Claim 8** The blood pump according to any one of claims 1 to 7, wherein the drive shaft is pivotally supported at least in the region of the proximal end of the pump housing. A blood pump characterized by that. **Claim 9** The blood pump according to claim 8, wherein the drive shaft is additionally pivotally supported in the region of the distal end of the pump housing. A blood pump characterized by that. **Claim 10** The blood pump according to any one of claims 1 to 9, wherein a plurality of the helical structures each include a helical support column. A blood pump characterized by that. **Claim 11** The blood pump according to claim 1, wherein the conveying element includes at least one foldable segment, and the at least one foldable segment is formed such that the rotational direction of the conveying element causes fluid to be conveyed from the distal end to the proximal end. A blood pump characterized by that. **Claim 12** The blood pump according to claim 2 or 3, wherein the at least one foldable segment is formed such that the rotational direction of the conveying element causes fluid to be conveyed from the distal end to the proximal end. A blood pump characterized by that. **Claim 13** The blood pump according to claim 11 or 12, wherein when the pump housing is moved from the compressed state to the expanded state, the unfolding direction of the at least one foldable segment is oriented opposite to the rotational direction. A blood pump characterized by that. **Claim 14** The blood pump according to any one of claims 1 to 13, wherein the drive shaft is a hollow shaft including a core in the region of the pump housing. A blood pump characterized by that. **Claim 15** A blood pump according to any one of claims 1 to 14, wherein the "austenite finish" (A ｆ ) temperature of the pump housing is lower than 34 °C. **Claim 16** The blood pump according to claim 15, wherein the "austenite finish" (Af) temperature of the pump housing is lower than 30°C. A blood pump characterized by that. **Claim 17** The blood pump according to claim 16, wherein the "austenite finish" (Af) temperature of the pump housing is lower than 20°C.

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