Flexible catheter

Abstract

To provide a flexible catheter with a flexible drive shaft.SOLUTION: A flexible catheter (1) comprising a drive shaft (2), a sleeve (6) surrounding the drive shaft (2), and a sheath (7) surrounding the drive shaft (2) and the sleeve (6), wherein the drive shaft (2), the sleeve (6), and the sheath (7) are flexible, and wherein the drive shaft (2) comprises a cavity (29) extending axially through the drive shaft (2), and a plurality of coaxial windings (31, 32) helically running around the cavity (29) of the drive shaft (2); The drive shaft (2) comprises at its distal end a pump rotor (20), which is fastened in a rotationally fixed manner on the outer circumference of the drive shaft (2).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a flexible catheter with a flexible drive shaft according to the preamble of the main claim, and to a blood pump assembly comprising such a catheter. [Background technology]

[0002] Such catheters are typically used inside the human or animal body to generate or transmit torque or rotational movement. A drive shaft runs axially along the longitudinal extension of the catheter between the proximal end of the catheter and the distal end of the catheter. Typically, the proximal end of the drive shaft is connected to a drive motor outside the body to generate and transmit torque or rotational movement up the drive shaft. A rotating or functional element designed according to the respective application is connected to the drive shaft at its distal end in a rotatably fixed manner. As for the functional element, it can be, for example, a milling cutter, a rotor ablator, or the case of a pump rotor for delivering blood.

[0003] For many applications, it is necessary to guide the catheter along a desired path through the body, for example, along or within a blood vessel, in order to position the distal end of the catheter at a desired location within the body, for example, within a ventricle of the heart, for the duration of the respective application. Apart from the necessary flexibility and pliability, further criteria generally must be met. For example, in some applications, rotational movement needs to be generated or transmitted by the drive shaft at very high rotational speeds; for example, the required rotational speeds can exceed 10,000, 20,000, or even 30,000 revolutions per minute, such as those already mentioned in the case of blood delivery. Furthermore, in cases where rotational movement must be generated over longer periods of time, such as over hours, days, or even weeks, as may be the case when delivering (pumping) blood, particularly high demands are placed on the mechanical and chemical load-bearing capacity of the catheter. The material fatigue and damage process to the catheter drive shaft and other components should simply proceed as slowly as possible, and moreover, as predictably and controllably as possible. Rupture and breakage of the drive shaft during operation should be ruled out with as much certainty as possible in critical applications, such as when delivering blood. This makes it undesirable for a flexible drive shaft to operate within a sheath that is too stiff and causes wear on the shaft.

[0004] On the other hand, if shaft failure does occur despite this, it must be ensured to the greatest extent possible that the end of the shaft, which typically flares open, does not move at high speed through the catheter sheath, which is usually made of plastic, and which would then rotate freely within the vessel. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] European Patent Application Publication No. 2399639 [Non-patent literature]

[0006] [Non-Patent Document 1] "The Sternotomy Hemopump. A second generation intraarterial ventricular assist device." Wampler RK et al., ASAIO J. 1993 Jul-Sep;39(3):M218-23 Summary of the Invention [Problem to be solved by the invention]

[0007] It is therefore an object of the present invention to propose a flexible catheter with a flexible drive shaft, which is as reliable as possible and as suitable as possible for permanent operation at high speeds. Furthermore, a blood pump arrangement is proposed, which is likewise as reliable as possible and as suitable as possible for permanent operation at high speeds. [Means for solving the problem]

[0008] This object is achieved by a catheter according to the main claim and by a catheter and blood pump arrangement according to the auxiliary claim. Preferred embodiments and further developments can be inferred from the dependent claims.

[0009] As explained below in detail, this patent application discloses several aspects, each of which is part of a coherent invention. On the other hand, each of the aspects also represents an autonomous invention in itself. Therefore, the aspects can be realized independently of one another (and, in each case taken by itself, represent a special further development of the generic catheter according to the preamble of the main claim). Moreover, they can be infinitely combined with one another to synergistically improve the generic catheter or the blood pump arrangement comprising the generic catheter. Thus, for example, a generic catheter can be designed according to one of these aspects and, at the same time, according to one (or more) additional aspects. This catheter is then a particularly advantageous embodiment of the catheter according to the first-mentioned aspect. Therefore, each aspect also allows for a further development of each of the other aspects.

[0010] The first of these aspects relates to the material or material properties of the drive shaft, the second to the geometric design of the drive shaft, the third to the design of the sleeve, the fourth to the connection between the drive shaft and the drive motor, the fifth to the mounting of the drive shaft, and the sixth to the lubricant for the drive shaft, each of which contributes to improving the load-bearing capacity and reliability of the catheter or blood pump component.

[0011] Thus, a generic flexible catheter includes a drive shaft, a sleeve surrounding the drive shaft, and a sheath surrounding the drive shaft and sleeve, wherein the drive shaft, sleeve, and sheath are flexible. The drive shaft includes a coupling element or coupling head at its proximal end for connecting the drive shaft to a drive motor.

[0012] Typically, the total (axial) length of the catheter is between 50 cm and 200 cm, generally between 80 cm and 150 cm. Typically, the total (axial) length of the drive shaft, sleeve, and sheath is also in each case within one of these ranges. Therefore, the flexibility or pliability of the catheter, and in particular the flexibility or pliability of the drive shaft, sleeve, and sheath, should be sufficient to allow the catheter to be elastically bent with a radius of curvature in the range of 20 mm to 40 mm, preferably in the range of 25 mm to 35 mm, and in particular about 30 mm. Such a curvature, in particular of the drive shaft and sleeve rotating at operating speed, should, if possible, only deform elastically, and therefore, if possible, should not cause permanent (plastic) deformation or change of the drive shaft or sleeve. In particular, such elastic bending with the described radius of curvature should also be possible by approximately U-shaped bending of the catheter by about 180°, thereby causing the catheter to be continuously curved, for example, along an axial section of the catheter having a length of about 80 mm to 150 mm, typically 100 mm to 120 mm (depending on the radius of curvature). Such bending of the catheter occurs, for example, when the catheter passes through the aortic arch and into the left ventricle. Moreover, the described regular changes in radius of curvature typically occur due to regular cardiac activity, and the position of the curve relative to the catheter can also change regularly.

[0013] In many cases, it is not necessary for the catheter to have such flexibility along its entire axial longitudinal extent. It may already be sufficient for this to be provided in a specific axial section (or several axial sections). In many cases, at least the distal end piece or distal partial piece of the catheter will have such flexibility, as in the case of blood delivery, for example, when the distal end of the catheter must be placed in a ventricle. This distal end piece or partial piece can have, for example, an axial length in one of the above-mentioned length ranges.

[0014] As will be explained in more detail further below, the flexibility and flexibility of the catheter or drive shaft may in some cases not be too great, particularly in those axial sections of the drive shaft that run distally or proximally outside the sleeve or exit the sleeve, such that localized reinforcement of the drive shaft to a certain extent may be advantageous in at least one of these sections or may even be necessary depending on the requirements of the respective application. Minimization of vibrations can advantageously be achieved by such reinforcement, and by such measures the risk of hemolysis may also be reduced.

[0015] According to a first aspect of the present invention, the catheter drive shaft may be composed entirely or at least locally of an alloy containing, in each case, at least 10% by weight of chromium, nickel, and cobalt. The alloy preferably contains at least 30% by weight of nickel, but preferably not more than 40% by weight of nickel. The alloy preferably contains at least 30% by weight of cobalt, but preferably not more than 40% by weight of cobalt. The alloy preferably contains at least 15% by weight of chromium, but preferably not more than 25% by weight of chromium. The alloy also preferably contains molybdenum, preferably at least 5% by weight, but preferably not more than 15% by weight of molybdenum.

[0016] The alloy may, for example, have an alloy composition of about 35% nickel, about 35% cobalt, about 20% chromium, and about 10% molybdenum by weight. These alloy compositions of the alloy may be greater or less than, in each case, by up to 3% by weight, or greater or less than, in each case, by up to 2% by weight. The alloy compositions of these elements may correspond to the alloy compositions of these elements in Alloy MP35N®, or may correspond to the alloy compositions of these elements in Alloy 35NLT®, or may differ from these by up to 2% by weight, or may differ from these by up to 1% by weight, or may differ from these by up to 1% by weight, in each case. Furthermore, the alloy may contain additional alloying elements. These may be selected and weighted according to the alloying elements of Alloy MP35N® or Alloy 35NLT®.

[0017] Preferably, with regard to the alloy, this is the case for MP35N® or 35NLT® or is produced in a corresponding (or the same) manner, i.e. by corresponding (or the same) method steps and by corresponding (or the same) method parameters as for MP35N® or 35NLT®. For example, it is possible to envisage that the alloy of the drive shaft or the entire drive shaft is work-hardened or produced or formed by applying (high) cold forming or work-hardening. The degree of work-hardening of the material of the drive shaft and / or sleeve is, for example, between 35% and 70% and / or between 40% and 60%. A tensile strength of the material in the region between 1900 MPa and 2200 MPa can result from this.

[0018] The relationships between yield point, tensile strength, elongation at break, and work hardening using the example of material 35NLT (based on details from manufacturer Fort Wayne Metals) are illustrated by way of example in Figures 16 and 17. This example shows that different heat treatment conditions and work hardening of materials can generally lead to very different material properties. In many cases, these were simply found to be inappropriate for flexible drive shafts with the benefit of hindsight.

[0019] For example, high work hardening is not unimportant, since it can lead to a reduction in the maximum elongation at break and toughness of the material. The reverse bending strength of the drive shaft and the achievable bending radius of the shaft can be adversely affected by this. On the other hand, low work hardening is accompanied by a relatively low material hardness and tensile strength. Too low a hardness has a direct effect on the wear behavior of the shaft and therefore on its fatigue strength, and can result, for example, in increased wear and abrasion during operation. This is particularly important in the case of sliding / friction pairings, as is typical for flexible shafts. Reduced tensile strength results in a low reverse bending strength.

[0020] Optimization of stable and durable flexible drive shafts is highly complex because different optimization objectives of drive shafts involve divergent material properties such that no standardized, meaningfully applicable optimization method or clear parameter window results in this regard.

[0021] However, surprisingly, completely or at least locally, 1800N / mm 2 to 2400N / mm 2 Preferably, the tensile strength is in the range between 2034 N / mm 2 from 2241N / mm 2 It has been found that drive shafts constructed from a material having a tensile strength of 295 KSI to 325 KSI lead to good results. In particular, the material may be one of the alloys described herein, thus containing at least 10% by weight of chromium, nickel, and cobalt in each case. However, apart from these alloys, other materials are also contemplated for the drive shaft, such as metallic and non-metallic materials, in particular plastics and composite materials.

[0022] Drive shafts constructed entirely or at least partially from such alloys or materials are also suitable for applications at very high speeds and long, permanent operations, making it possible for such drive shafts to maintain the speed ranges mentioned earlier for longer periods of time. Torque transmitted by drive shafts at such high rotational speeds, however, is typically relatively low, especially when delivering blood, and torque for driving expanded pump rotors is typically greater due to their larger diameter. However, while applications of Alloy MP35N® or Alloy 35NLT® may be known for different medical devices, such as stylets, due to, for example, their load-bearing capacity and their corrosion resistance, their suitability for flexible drive shafts is surprising. This is due to the special requirements described, in particular at high speeds, long operating durations and large curvatures, in light of the fact that in practice more than 500,000,000 complete cycles and, in extreme cases, more than 1,000,000,000 cycles can occur in application as a blood pump.

[0023] To date, alloys with a relatively high iron or titanium content have been applied to drive shafts, particularly blood pumps, in order to achieve high load-bearing capacity. However, as has been discovered within the scope of the present invention, it is possible, and indeed should be possible, to dispense with high iron and titanium contents as much as possible, so as to enable permanent operation at high rotational speeds. The weight fractions of iron and titanium are more preferably selected to be relatively low, for example, less than 2% by weight, or even less than 1% by weight in each case. In principle, it is possible to completely dispense with iron and titanium in the alloy composition, which corresponds to a weight fraction of less than 0.1% in each case.

[0024] According to a first aspect, the drive shaft may be entirely or at least locally composed of an alloy having a weight composition of less than 2%, or preferably less than 1%, or especially preferably less than 0.1% iron. According to a first aspect, the drive shaft may be entirely or at least locally composed of an alloy having a weight composition of less than 2%, or preferably less than 1%, or especially preferably less than 0.1% titanium.

[0025] The drive shaft, sleeve, sheath and / or any bearing elements present are made of biocompatible materials as far as possible, or at least the outer surface of each component is made of biocompatible materials.

[0026] According to a second aspect of the present invention, the drive shaft may include a cavity extending axially therethrough. The drive shaft may thus be a hollow shaft case. The cavity may extend through the drive shaft along the entire longitudinal extent of the drive shaft. High flexibility of the drive shaft, coupled with a relatively high torsional stiffness, may be achieved by such a cavity. Flexibility may be further increased if the drive shaft includes multiple or multiple coaxial windings helically running around the cavity of the drive shaft. Furthermore, torsional and bending stresses may be converted by the windings into axial tensile or compressive stresses, and by such means, the load on the drive shaft may be reduced. Furthermore, the windings of the drive shaft may be arranged in two or more coaxial layers of the drive shaft. The windings in different coaxial layers then preferably have opposite winding directions. Tensile and compressive stresses between the layers, as well as those caused by torsional stresses, may thus be fully or partially offset. Also, bending stresses in the drive shaft as a whole can therefore be reduced.

[0027] Regarding the winding of the drive shaft, this is typically the case with a wound wire or several corresponding wound wires. The drive shaft can include exactly one or several such wires in each layer, for example, 1 to 8 wires, preferably 4 to 6 wires, and particularly preferably 5 wires. The wire or wires are preferably composed of the alloys described above. The wire or wires typically have a diameter in each case ranging from about 0.09 mm to about 0.21 mm, preferably from about 0.135 mm to about 0.165 mm. The outer diameter of the drive shaft is typically in the range of about 0.53 mm to about 1.32 mm, preferably from about 0.79 mm to about 0.97 mm. An outer diameter of the drive shaft of less than 1 mm is particularly preferred. The inner diameter of the drive shaft is typically in the range of about 0.17 mm to about 0.39 mm, preferably from 0.25 mm to about 0.31 mm. In the case of two concentric layers, axially adjacent windings on the inner layer are in contact with one another, while axially adjacent windings on the outer layer preferably are not in contact with one another but have an axial distance (in each case, assuming a curve-free drive shaft alignment) in the range of about 0.018 mm to about 0.042 mm, preferably about 0.027 mm to about 0.033 mm.

[0028] A small outer diameter of the catheter can also be achieved by a small outer diameter of the drive shaft, by which means reduced tissue trauma at the puncture site can be achieved. Further advantages that can be achieved by a low outer diameter of the drive shaft are lower friction and wear problems due to reduced peripheral speed of the drive shaft, lower vibration problems due to reduced mass of the drive shaft, and reduced disturbance / interference of the motor current signal due to the resulting vibrations, and reduced risk that, for example, calcifications that may be present in the blood vessel will detach from the vessel wall and become circulating, potentially with potentially fatal consequences for the patient.

[0029] It has therefore surprisingly been found that the transmission of sufficiently high torques, for example to drive an inflatable pump rotor in an inflated condition, over longer periods of time is possible even with the low outer diameter of the drive shaft described herein of less than 1 mm. It has therefore been found, inter alia, that the particular ranges of wire diameters, and those specified above, are particularly advantageous in the case of shafts constructed from such wires, and furthermore that the optimum ranges for the diameters of the individual wires are related to the outer diameter of the drive shaft in a non-obvious manner.

[0030] Moreover, it is possible to foresee that the windings of the drive shaft are manufactured or formed by (high) cold forming or work hardening, so as to improve the resilience and durability of the drive shaft.

[0031] The cavities may be filled with a reinforcing material, either completely or within the axial sections of the drive shaft, to set and possibly locally increase the stiffness and stability of the drive shaft within each axial section. As already explained in the context of the first aspect of the invention, a sufficient flexibility of the drive shaft, as well as a sufficient stiffness of the drive shaft, is also necessary for reliable operation of the catheter, particularly at high speeds and for longer operating durations, for example, to enable stable rotation of the drive shaft, particularly within the axial sections of the drive shaft that run distally or proximally outside the sleeve (the distal and proximal end pieces of the drive shaft, respectively). The first and second aspects of the invention thus synergistically complement each other. Therefore, a preferred embodiment foresees that the distal end piece of the drive shaft and / or the proximal end or end piece of the drive shaft are reinforced. The reinforced distal or proximal end or end piece preferably has a length of between 10 mm and 60 mm, and particularly preferably between 20 mm and 50 mm. The drive shaft is preferably reinforced in these regions, and bearing elements (additionally or instead of the sleeve, i.e., instead of the sleeve) are arranged for axial and / or radial mounting of the drive shaft. It may also be advantageous to reinforce the drive shaft in the regions where it enters or exits the sleeve proximally and, as a result, is not guided within the sleeve. It may also be advantageous to reinforce the drive shaft in the regions where it enters or exits the sleeve distally. Indeed, in these transition regions, for example, bending loads on the drive shaft or other loads, such as vibration loads, may be reduced by reinforcing the drive shaft.

[0032] Materials characterized by high rigidity and, at the same time, relatively high elastic deformability are suitable as reinforcing materials for reinforcing the drive shaft. In particular, the reinforcing material should withstand all bending that the catheter or its pump head undergoes during implantation and operation. For example, rust-resistant austenitic steels are considered as reinforcing materials, such as steels according to material number DIN 1.4310.

[0033] Also, alternatively or in addition to the described reinforcing materials, suitable reinforcement can be realized by (axial and / or radial) welding or soldering of adjacent (axially or radially) windings of the (helical) drive shaft. Furthermore, it is also possible that a particular (and under certain circumstances sufficient) reinforcement of the drive shaft can be realized by a distal functional module, which is typically fastened in a rotatably fixed manner onto the outer periphery of the drive shaft, such as a pump rotor.

[0034] According to a third aspect of the present invention, the sleeve can be designed as a bearing coil with multiple windings. The windings of the bearing coil run axially around the drive shaft in a helical manner. The bearing coil can be, for example, a wound flat tape. The flat tape preferably has a width (measured axially) that is at least three times, preferably six times, greater than its thickness (measured radially). Typically, the width of the windings is in the range of about 0.36 mm to about 0.84 mm, preferably about 0.54 mm to about 0.66 mm. The thickness of the windings is typically in the range of about 0.06 mm to about 0.14 mm, preferably about 0.09 mm to about 0.11 mm. The inner diameter of the sleeve is typically in the range of about 0.6 mm to about 1.4 mm, preferably about 0.9 mm to about 1.1 mm. The outer diameter of the sleeve is typically in the range of about 0.72 mm to about 1.68 mm, preferably about 1.08 mm to about 1.32 mm, the pitch of the bearing coils is preferably in the range of about 0.43 to about 0.98, preferably about 0.63 to 0.77, and the inner diameter of the sleeve corresponds to, and in particular is larger than, the outer diameter of the flexible drive shaft.

[0035] If the bearing coil is designed as a wound flat tape, the manufacturing tolerances for the (axial) tilt of the windings relative to the longitudinal axis of the bearing coil (assuming the bearing coil is straight and uncurved) are as low as possible. The tilt is preferably less than 10°, particularly preferably less than 5°. Therefore, the inner surface of the sleeve or the inner surface of the windings of the bearing coil preferably forms a cylindrical partial surface instead of a conical partial surface (tilt). Inclination of the windings relative to the longitudinal axis leads to a reduction in the available bearing surface and to a greater pressure load on the drive shaft. The outer edges of the flat tape are preferably rounded as much as possible to avoid pressure peaks on the drive shaft as much as possible. The radius of curvature of the edges is preferably 0.04 mm or greater.

[0036] The sleeve may be made entirely or at least locally of the alloy, and accordingly the description of the alloy of the drive shaft may be given to the alloy of the sleeve. In particular, the sleeve may be made entirely or at least locally of the same material, e.g., the same alloy as the drive shaft.

[0037] In clinical trials, very good results were achieved in fatigue tests using the same material for the drive shaft and sleeve under different pulsatile loads and with bending radii significantly smaller than 50 mm. This is surprising in many respects. For example, specifically for patient safety reasons, it is recommended to design the flexible shaft from a relatively hard, wear-resistant material compared to the drive shaft, so that in the event of shaft fracture, which would normally lead to splicing of the shaft in the fractured area, the drive shaft would not rub through the sleeve and even the softer sheath of the catheter during subsequent operation, and would not rotate openly within the blood vessel. Moreover, in classical engineering, the use of identical materials for sliding or friction partners is usually discouraged because in this case, so-called "eating" or corrosion of the workpieces may occur, resulting from the fact that the individual molecules of the two sliding / friction partners connect with each other and then tear away from the molecular interconnections of the other parts. The fact that it is very difficult or impossible to predict which of the two parts will wear out thereby appears to be of particular importance. Therefore, the use of the same material for the rapidly rotating flexible shaft and for the bearing coils positioned around it is now proposed, which is surprising to those skilled in the art.

[0038] A fourth aspect of the present invention relates to the design of the drive shaft's proximal coupling element or coupling head, which, surprisingly, can significantly improve the reliability of the catheter and its suitability for permanent applications, especially when this aspect is combined with one of the other aspects. The basic idea of ​​the fourth aspect is that the connection between the drive shaft's coupling element (which itself is connected to the drive shaft in a manner that is as rigid as possible and is rotatably, tractionally, and compressibly fixed) and the drive motor's coupling element (which corresponds to it but is rotatably fixed), but where a compensating movement between the drive shaft coupling element and the drive motor coupling element is allowed in the axial direction, can often significantly reduce the axial compressive and tensile stresses in the drive shaft. For this purpose, the drive shaft and drive motor coupling elements can include axial sliding surfaces that correspond to each other and typically run parallel to the (local) rotation axis or longitudinal axis of the respective coupling elements. Therefore, the shape of these axial sliding surfaces or their outer or inner contours do not change axially (and thus along the rotation axis or longitudinal axis). For example, the coupling element of a drive shaft can have the shape of a square end or another profile piece, which has a cross-sectional area (defined perpendicular to the rotation axis or longitudinal axis) or outer contour that is constant in the axial direction and thus along the longitudinal extension or rotation axis. The coupling element of a drive motor can therefore be designed as a correspondingly designed receiver with a square end or profile piece.

[0039] As previously mentioned, the catheter can include a pump rotor at the distal end of the drive shaft, for example, for delivering blood, which is fixedly connected to the drive shaft. Depending on the configuration, design, and pitch angle of the pump rotor's braiding, the pump rotor can be configured, for example, for proximal delivery (proximal delivery direction, i.e., toward the proximal end of the catheter) or distal delivery (distal delivery direction, i.e., toward the distal end of the catheter). A fifth aspect of the invention relates to axial mounting of the pump rotor, whereby the catheter's thrust bearing is matched to the delivery direction of the pump rotor, so that axial bearing forces act on the drive shaft primarily or exclusively as axial tension (pulling) forces (and to a lesser extent, or not at all, as axial compression forces). Drive shaft loads, especially at high speeds, can thereby be surprisingly significantly reduced. Moreover, it has surprisingly been found that damage to the blood resulting from pumping action is low with such a blood pump design. This contemplates that in the case of a proximal delivery orientation, a thrust bearing be located proximal to the pump rotor and designed to counteract distally directed axial displacement of the drive shaft (caused by the proximal delivery effect of the pump rotor). In the case of a distal delivery orientation, a thrust bearing be located distal to the pump rotor and designed to counteract proximally directed axial displacement of the drive shaft.

[0040] The thrust bearing can include, for example, a first thrust bearing element and a second thrust bearing element, where the first thrust bearing element is rotatably connected to the drive shaft and the second thrust bearing element is fixedly connected to the sleeve or sheath. The first thrust bearing element and the second thrust bearing element include sliding surfaces (which may also be referred to as abutment surfaces or end faces) facing each other and preferably annular, which, when in contact with each other, prevent axial displacement of the drive shaft in at least one direction. The sliding surfaces thus mentioned overlap each other radially. The first thrust bearing element can be designed as a radial extension of the drive shaft, but can also be designed as a ring that is fastened onto the drive shaft, for example by crimping. As regards the second thrust bearing element, it can at the same time be the case of a radial bearing element, for example, the sliding surface facing the drive shaft is preferably designed in a cylindrical manner and is arranged coaxially with respect to the rotation axis of the drive shaft.

[0041] Preferably, at least one of the sliding or abutment surfaces mentioned, preferably at least that of the first bearing element of the thrust bearing, has profiling, such that the two sliding surfaces, together with their interaction with a (fluid) lubricant, form a hydrodynamic plain bearing. A lubricant as further described below is preferably applied as lubricant. The profiling has the function of creating lubricant bow waves or pressure waves between the two sliding surfaces, which run around the drive shaft during rotational movement. Surprisingly, this design of the sliding surfaces could reduce the increased wear in this area by more than 50%.

[0042] For example, the profiling of each sliding surface can preferably include 6 to 24 protrusions and / or recesses, which can preferably have a height or depth of about 0.03 mm to about 0.1 mm in each case. Typically, the protrusions and / or recesses can be arranged across each sliding surface in a manner that is uniformly distributed along the circumferential or peripheral direction of the sliding surface. The protrusions can be identical, and likewise, the recesses can be identical. A protrusion can be laterally adjacent to a recess, or vice versa. In particular, the profiling can be designed as a series of alternating protrusions and / or recesses (along the peripheral direction). For example, the protrusions and / or recesses can be designed as ribs and grooves, respectively, which typically extend from the inner edge of the sliding surface facing the drive shaft toward the outer edge of the sliding surface away from the drive shaft. Typically, the grooves or ribs run exactly from the inner edge to the outer edge and therefore have a length corresponding to the width, measured radially, of the respective sliding surface.

[0043] The ribs or grooves typically have a width (measured in the circumferential direction) in the range of about 0.08 mm to about 0.5 mm. The width of the ribs or grooves can be constant or can vary radially. Typically, the profiling includes alternating recesses or grooves and protrusions or ribs along the circumferential direction of the sliding surface. If the grooves then have a constant width, the ribs typically widen radially outward. Such embodiments can often be easily manufactured, inter alia, by milling. On the other hand, if the ribs have a constant width, the grooves typically widen radially outward. However, it is also possible for the ribs and grooves to widen radially outward. This last embodiment can be easily manufactured, inter alia, by laser cutting. The grooves or ribs can also be locally designed to be spiral and thus extend over an arcuate path (e.g., a circular path) from the inner edge to the outer edge of the sliding surface.

[0044] The catheter can include the above-mentioned bearing elements and further bearing elements for radial and / or axial mounting of the drive shaft, such as zirconium oxide (ZrO2; also called zirconium dioxide, zirconia), especially zirconium oxide stabilized with yttrium, aluminum oxide (AlO x , typically Al2O3), ceramics and alloys as described in the context of the first embodiment are in each case considered as materials for the bearing elements, for example.

[0045] According to a sixth aspect of the present invention, the cavity or intermediate gap between the drive shaft and the sleeve is filled with a lubricant, which is biocompatible and preferably physiological. This lubricant can be, for example, distilled water or an aqueous solution, such as saline and / or glucose solution. The solution can have a physiologically consistent salt concentration, i.e., 0.9%. However, isotonic saline solution or so-called Ringer's solution can also be envisaged. On the other hand, due to the fact that the lubricant is biocompatible, the construction of the catheter can be simplified, since its escape into the body does not necessarily need to be avoided. Although the proposed materials are used for the drive shaft, sleeve, and bearing elements, these components are relatively chemically stable with respect to corrosion by these (relatively corrosive) lubricants, and their application does not impair the reliability and suitability of the catheter for permanent operation. The use of saline solution is particularly advantageous. This is because such solutions are generally well tolerated by patients and have no side effects, especially with the presence of diabetes in the patient.

[0046] The proposed blood pump arrangement includes a catheter of the proposed type and a drive motor for generating rotational movement or torque. A rotatably fixed, preferably axially displaceable, connection exists between the drive motor or a coupling element of the drive motor as already described and a coupling element or coupling head of the drive shaft. Regarding the latter, reference is made to the explanations in this regard and in the context of the fourth embodiment. The drive motor can be designed to generate high rotational speeds, for example, in the range of 10,000 to 40,000 revolutions per minute. A functional element connected in a rotatably fixed manner to the distal end piece of the drive shaft is designated as a pump rotor. The catheter includes a pump casing at its distal end, in which the pump rotor is disposed. For example, the pump casing can be designed so that it can be brought from an expanded (or compressed) state to a compressed (or expanded) state (e.g., under a (tensile) force acting toward the proximal (or distal) end of the catheter). Patent document 1 is referenced for details. Using the pump configuration, it is possible to envision, for example, a catheter with its distal end forward being pushed through the femoral artery, through the aortic arch, and into the left ventricle of the heart, with the pump casing remaining in the left ventricle. Downstream tubing is connected proximally to the pump casing and then typically runs through the aortic valve, where it can, for example, direct blood, driven by the pump rotor, from the pump casing into the aorta. The proximal end of the catheter, and in particular the proximal end of the drive shaft, and the drive motor, are located outside the body.

[0047] These and similar applications subject the drive shaft to various external force effects and cyclic bending loads, and possibly the catheter's or blood pump component's bearing elements. Due to pulsatile blood pressure or flow changes associated with the ventricles or blood vessels, e.g., the left or right ventricle or the aorta, and due to changes in body position or posture, particularly abdominal or leg movements proximal to the puncture site, the external force effects and cyclic bending loads can be transmitted into the catheter, for example, by the heart's inner wall, on which the catheter rests or is possibly supported (e.g., via a so-called pigtail tip). Despite these loads, blood can be delivered using the proposed catheter and blood pump component at high rotational speeds of the pump rotor in the stated speed range, such as in the blood pump component applications described above, for longer periods of time, e.g., hours, days, or even weeks.

[0048] For example, as can be inferred from [Patent Document 1], laboratory shaft failures can generally be realistically simulated simply under pulsating compressive loads and bend radii of less than 2 inches (less than 50.8 mm). The importance of multiple shaft loading is thereby made clear. Apart from the pump configuration proposed herein, applicant is unaware of any pumps with flexible shafts and any that have been successfully applied under pulsating loads in the aortic arch for longer periods of time. This is due to the handling of the flexible shaft problem, which to date has not been successful. Furthermore, previously, particularly in [Patent Document 1], the use of a three-ply shaft instead of a two-ply shaft was seen as essential to improve the service life of flexible shafts. The drive shaft proposed herein, in contrast, has durability and load-bearing capacity at small bend radii (less than 50 mm) and pulsating loads that is comparable to or even significantly longer than conventional drive shafts with two-ply designs, and therefore, in embodiments, has a significantly smaller diameter than conventional drive shafts.

[0049] The outer surface of the drive shaft can surprisingly have a relatively high roughness RZ. The roughness RZ can be, for example, in the range of 0.01 μm to 1 μm, preferably in the range of 0.1 μm to 0.8 μm. The roughness RZ can be, for example, approximately 0.6 μm. The fact that such good results were achieved in durability tests with a relatively high roughness of the drive shaft surface is quite surprising. This is because, particularly when a relatively corrosive substance such as physiological saline solution or glucose solution is used as a lubricant as proposed herein, theoretical considerations usually dictate that a surface as smooth as possible is preferred to minimize wear due to friction, because the lubricating effect of such a substance is inaccessible to lubricants commonly used in industry, and design principles normally applicable to classical engineering obviously cannot be directly applied in this regard.

[0050] As previously described, a flexible catheter of the type proposed herein includes a drive shaft, a sleeve surrounding the drive shaft, and a sheath surrounding the drive shaft and sleeve, wherein the drive shaft, sleeve, and sheath are flexible, and the drive shaft includes a coupling element at its proximal end for connecting the drive shaft to a drive motor.

[0051] Moreover, the drive shaft may include an outer diameter of less than 1 mm. The drive shaft and / or sleeve preferably has a minimum of 1800 N / mm 2 to 2400N / mm 2 Tensile strength between 2034N / mm 2 from 2241N / mm 2The drive shaft and / or sleeve may be made of a material having a tensile strength between 0.01 μm and 1 μm. The drive shaft and / or sleeve may be made of a non-metallic or metallic material, at least locally. In the case of a metallic material, this is preferably the case of an alloy as already described further above, which therefore contains in each case at least 10% by weight of chromium, nickel, and cobalt. This alloy may have the characteristics already described above. The drive shaft and sleeve may be made entirely or at least locally of the same material. Moreover, as already described further above, the surface of the drive shaft may have a roughness between 0.01 μm and 1 μm, preferably between 0.1 μm and 0.8 μm. Naturally, the catheter may have all of the characteristics and combinations of characteristics that have been and will be described previously.

[0052] The described aspects of the invention are explained in more detail below by way of examples of particular embodiments of catheters of the type proposed herein and blood pump arrangements of the type proposed herein, which are represented diagrammatically in Figures 1 to 16. [Brief explanation of the drawings]

[0053] [Figure 1] 1 shows a catheter of the type proposed here in side view. FIG. [Figure 2] FIG. 2 shows a blood pump arrangement with the catheter shown in FIG. 1 in an implanted condition. [Figure 3] 2A and 2B show axial sections of parts of the drive shaft of the catheter of FIG. 1 in side view. [Figure 4] FIG. 4 shows a cross section through the drive shaft shown in FIG. 3, taken at the location marked AA. [Figure 5] FIG. 10 shows a side view of a distal end piece of a drive shaft reinforced with a reinforcing material. [Figure 6] 6 is a longitudinal section through the end piece shown in FIG. 5, taken at the location marked AA in FIG. 5. [Figure 7] FIG. 2 is a side view of the sleeve of the catheter shown in FIG. 1. [Figure 8] 8 is a cross-section through a partial region of the sleeve shown in FIG. 7, said partial region being the view characterized by A in FIG. 7. [Figure 9] 2 is a longitudinal section through the catheter shown in FIG. 1, taken in an axial partial section characterized by Y in FIG. 1. [Figure 10] FIG. 7 is a view of the distal end piece depicted in FIGS. 5 and 6, showing the pump rotor fastened thereon in a rotatably fixed manner. [Figure 11] 2 is a longitudinal section through the catheter shown in FIG. 1, taken in an axial partial section characterized by Z in FIG. 1. [Figure 12] 2 is a longitudinal section through a coupling module of the catheter shown in FIG. 1. [Figure 13] 10A and 10B show perspective views of examples of embodiments of bearing elements of the thrust bearing shown in FIG. 9. [Figure 14] 14A and 14B also show a perspective view of a further example embodiment of the bearing element shown in FIG. 13. [Figure 15] FIG. 1 shows the measured values ​​of yield point, tensile strength, and elongation at break for different values ​​of work hardening for material 35NLT®. [Figure 16] FIG. 16 is a diagram of the tensile strength and elongation at break measurements identified in FIG. 15 as a function of the degree of work hardening for material 35NLT®. DETAILED DESCRIPTION OF THE INVENTION

[0054] One or more repeating features that correspond to one another are characterized in the figures by the same reference numeral.

[0055] A particular embodiment of a flexible catheter 1 of the type proposed here is represented diagrammatically in Figure 1. The catheter 1 comprises a flexible drive shaft 2, of which the proximal end piece 3 can be seen in this figure, said end piece protruding (cantilevered) from a proximal coupling module 4, at whose proximal end the drive shaft 2 comprises a coupling element 5 for connection of the drive shaft 2 to a drive motor (see Figure 2). Moreover, the catheter 1 comprises a flexible sleeve 6 (not shown here, but see Figures 7 to 9), which surrounds and is radially attached to the drive shaft 2, and a flexible sheath 7 which surrounds the drive shaft 1 and the sleeve 6. Thus, the coupling module 4 and the proximal end piece 3 of the drive shaft 2 are arranged at the proximal end 8 of the catheter 1, while at its distal end 9, the catheter 1 includes a pump head 10, which comprises a pump casing 11, a terminal housing 13, and downstream tubing 12. The terminal housing 13 is arranged distally of the pump casing 11 and is for the drive shaft 2, and the downstream tubing 12 is proximally adjacent to the pump casing 11 (elements running through the downstream tubing 12 are represented by dotted lines in FIG. 1 ). A support element 14 in the form of a so-called pigtail tip is arranged distally on the terminal housing 13. Furthermore, the catheter 1 includes a lock 15, the function of which is to radially compress the pump head 10 when it is retracted into the lock 15. The pump head 10 in this compressed state can then be introduced through an introduction lock (not shown) and implanted therethrough. The introduction lock can, for example, be fixed at the puncture site on or in the patient's body, thus likewise supporting the catheter 1 at this site. Reference is made in this context to US Pat. No. 5,649,999.

[0056] This catheter as part of a blood pump arrangement 16 is represented in an implanted condition in a very schematic manner in Figure 2. Shown is the use or application of the catheter 1 and the blood pump arrangement 16, with which the drive shaft 2 of the catheter 1 is connected in a rotatably fixed manner (but axially displaceable manner; see the explanation for Figure 12) via a coupling element 5 to a corresponding coupling element 17 of a drive motor 18 of the blood pump arrangement 1. The drive motor 18 is designed to produce a high rotational speed in the region between 10,000 revolutions per minute and 40,000 revolutions per minute.

[0057] As shown in FIG. 10 , a functional element designated as a pump rotor 20 is connected in a rotatably fixed manner to the distal end piece 19 of the drive shaft 2. The pump rotor 20 is arranged in a pump casing 11, which in this exemplary embodiment is designed so that it can be changed from a radially expanded condition to a radially compressed condition. For example, this can be achieved with the aid of the lock 15 or the aforementioned lead-in lock, preferably by the pump casing 11 being at least partially drawn into the respective lock while subjected to a (pulling) force acting toward the proximal end 8 of the catheter, thereby being compressed along a radial direction running transverse to the longitudinal direction. Thus, the pump casing 11 can be changed from a compressed condition to an expanded condition by an opposing force. U.S. Patent No. 5,949,294 is also incorporated herein by reference.

[0058] 2, the catheter 1 with its distal end 9 forward is inserted into the patient's body through the puncture site 21 into the femoral artery 22 and then pushed along the femoral artery 22, through the aortic arch 23, and into the left ventricle 24 of the heart 25. The pump casing 11 is thus positioned within the left ventricle 24, supported by the support element 14 on the inner wall 26 of the left ventricle 24, and the downstream tubing 12 runs through the aortic valve 27 into the aorta 28. Driven by the pump rotor 20, blood leaving the pump casing is thus directed through the downstream tubing 12 into the aorta 28. The proximal end 8 of the catheter 1, the proximal end piece 3 of the drive shaft 2, and the drive motor 18 are located outside the body.

[0059] In this example embodiment, the total (axial) length of the catheter and the total (axial) length of the drive shaft 2 are in each case approximately 150 cm (corresponding to an implantable length of approximately 140 cm), and the total (axial) length of the catheter's distal end 9 (including the pump head 12 and support element 14) is approximately 13.5 cm, enabling this application. Therefore, the flexibility or pliability of the catheter 1, and in particular the flexibility or pliability of the drive shaft 2, sleeve 6, and sheath 7, is substantial enough to allow the catheter 1 to be implanted and operated as described above. For this, these components, at least in the distal end 9 of the catheter, must be able to be elastically bent 180°, resulting in a radius of curvature R of the aortic arch 23, and in particular of the drive shaft 2, of typically approximately 30 mm, without plastic deformation, as shown in FIG. 2 .

[0060] As shown in Figures 4 and 6, the drive shaft 2 is designed as a hollow shaft and includes a cavity 29 extending axially therethrough, which allows for high flexibility of the drive shaft 2. The cavity 29 extends along the entire length of the drive shaft 2. However, this cavity 29 is completely filled with a reinforcing material 30, a so-called core, at least in the approximately 4.5 cm long distal end piece 19 of the drive shaft (see Figures 6, 9, and 10 and the related description further below), which allows for sufficient stiffness and vibration stability of the drive shaft 2, or of the distal end piece 19 of the drive shaft.

[0061] The drive shaft 2 includes multiple coaxial windings 31, 32 that run helically around the cavity 29 of the drive shaft 2 and convert torsional and bending stresses into axial tensile and compressive stresses. The windings 31, 32 are arranged in two coaxial layers 33, 34 (i.e., layers) of the drive shaft 2, with the windings 31 arranged co-radially (having the same winding radius) in the inner layer 33 and the windings 32 arranged co-radially in the outer layer 34. The windings 31 in the inner layer 33 have an opposite winding direction compared to the windings in the outer layer 34 so that tensile and compressive stresses can be canceled between the layers. In the example shown, the drive shaft has four wires 35 in the inner layer 33, the four wires 35 wound coaxially and in a common radial direction around the cavity 29, and the drive shaft has five wires in the outer layer 34, the five wires wound coaxially and in a common radial direction around the cavity, with axially adjacent windings 31 in the inner layer touching each other, but axially adjacent windings (in each case, a winding packet of five wires) 32 in the outer layer not touching each other and having an axial distance of about 0.03 mm (in each case, assuming a curve-free drive shaft alignment). The outer diameter d of the drive shaft in this example is a is approximately 0.88 mm, and the inner diameter d i is about 0.28 mm. The wire has a circularly round cross section with a diameter of about 0.15 mm. In this example, the circumferential direction of the windings 36 of the outer layer 34 is opposite the designated direction of rotation of the drive shaft 2 for (proximal) delivery of blood.

[0062] Here, this rotational direction corresponds to a clockwise direction (defined relative to the direction looking from the proximal end to the distal end of the drive shaft). In this case, the torque to be transmitted leads to the outer layer tending to contract and shorten. Since the inner layer 33 has an opposite tendency due to its opposite winding direction, these tendencies often advantageously cancel each other out. In principle, this mutual compensation can also be achieved in the opposite case, specifically when the winding direction of the outer layer corresponds to the rotational direction and the winding direction of the inner layer is opposite to the rotational direction of the drive shaft.

[0063] The wires 35, 36 of the drive shaft 2 are entirely composed of an alloy containing approximately 35% by weight of nickel, approximately 35% by weight of cobalt, approximately 20% by weight of chromium, and approximately 10% by weight of molybdenum. These alloy compositions can be greater or less than 3% by weight, or in each case, up to 2% by weight. Regarding the alloy, in this example, it is specifically the case of 35NLT®, but it could just as easily be the case of MP35N®. Thus, the weight composition of iron in the wire is less than 1% by weight, and the weight composition of titanium is less than 0.1% by weight. The alloy and the windings 31, 32 of the drive shaft are manufactured or formed during high cold forming and work hardening applications. In this example, a rust-free austenitic steel according to material number DIN 1.4310 (X10CrNi18-8) is selected as reinforcing material 30 to reinforce drive shaft 2. Alternatively, any other material that meets the requirements specified further above in this context may also be selected as reinforcing material.

[0064] 7 and 8, the sleeve 6 is designed as a bearing coil with a number of windings 37, which in the example shown run axially around the drive shaft 2 in a spiral manner. In this example, the bearing coil is provided by a wound flat tape 38. The flat tape 38 has a width B (measured axially) which is approximately six times greater than its thickness D (measured radially). In this example, the width B of the winding 37 is 0.6 mm, and the thickness D of the winding 37 is 0.1 mm. The winding 37 is furthermore angled, i.e. inclined, as little as possible, possibly by less than 5° with respect to the longitudinal axis L of the bearing coil (assuming the bearing coil is straight and without curvature), so that the inner surface 39 of the sleeve 6 formed by the winding 37 is as cylindrical as possible or forms as much of a cylindrical partial surface as possible. Additionally, the outer edges 54 of the flat tape are preferably as rounded as possible, with a radius of curvature r of approximately 0.04 mm. k The radius of curvature of the edge 54 is r k Preferably, the inner diameter D of the sleeve 6 is greater than 0.04 mm. I is about 1 mm, and the outer diameter of the sleeve D A is about 1.2 mm and has a gradient / pitch of about 0.7. In this example, the sleeve 6 or flat tape 38 is made from the same alloy as the wires 35, 36 of the drive shaft 2, and is therefore made here from 35NLT®, but could also be made from another one of the materials mentioned in this connection.

[0065] The drive shaft 2 and the sleeve 6 may also consist of materials other than the alloys mentioned here. The drive shaft 2 is preferably manufactured from the same material as the sleeve 6. Moreover, the surface of the drive shaft 2 can have a roughness RZ of about 0.6, by which means, surprisingly, particularly good wear resistance is achieved. Surprisingly, good wear properties, and therefore high operational reliability, can be achieved by these measures, which are extremely simple to implement.

[0066] A longitudinal cross section through an axial section of catheter 1, designated Y in Figure 1, is represented diagrammatically in Figure 9. In this section, catheter 1 includes bearing elements 40, 41, 42, which are arranged proximal to pump rotor 20 for radial and axial mounting of drive shaft 2.

[0067] The arrangement and design of these bearing elements 40, 41, 42 are matched to the pump rotor 20 of the catheter 1 shown in FIG. 10. This pump rotor 20 has a braiding 43 whose configuration, design, and pitch angle are configured to deliver blood proximally (in the proximal delivery direction, i.e., toward the proximal end of the catheter). Bearing elements 40 and 41 form a thrust bearing 44, which is located proximally of the pump rotor 20 (bearing element 41 is the first thrust bearing element of the thrust bearing 44, and bearing element 40 is the second thrust bearing element of the thrust bearing 44). Due to the design and arrangement of these (thrust) bearing elements 40, 41, the thrust bearing 44 is designed to resist distally directed axial displacement of the drive shaft 2 (caused by the effect of the proximally delivering pump rotor 20). The predominantly acting axial bearing force thus acts on the drive shaft 2 as a tension force during operation of the blood pump component.

[0068] The (first) bearing element 41 is preferably designed in an annular manner and is connected to the drive shaft 2 in a rotatably fixed manner, for example by crimping. In contrast, the (second) bearing element 40, like the bearing element 42, is fixedly connected to the sleeve 6 and the sheath 7. The bearing elements 40, 41 have annular sliding surfaces 45 and 46, respectively, which face each other and, when in contact with each other, prevent axial displacement of the drive shaft 2 in the distal direction. The sliding surface 46 of the (first) bearing element 41 has a profiling (see Figures 13 and 14 and the associated description below), which promotes the formation of a stable lubricant film between the two sliding surfaces 45, 46 and essentially enables the design of the thrust bearing 44 as a hydrodynamic sliding bearing. The lubricant film, i.e., a hydrodynamic bearing in this example, is formed using a lubricant, which will be further described below. Furthermore, bearing element 40, as well as bearing element 42, are in each case designed as radial bearing elements with a sliding surface facing drive shaft 2, are designed in a cylindrical manner and are arranged coaxially with the rotational axis of drive shaft 2.

[0069] Moreover, as can be seen in FIG. 9, the drive shaft 2 is reinforced by reinforcing material 30 in the axial section where it emerges distally from the sleeve 6, i.e. where it is mounted by bearing elements 40, 41, 42.

[0070] A longitudinal section through an axial section of catheter 1, characterized by reference numeral Z in Fig. 1, is represented diagrammatically in Fig. 11, which includes, among other things, terminal housing 13, which is adjacent to pump casing 11. Terminal housing 13 is designed in a tubular manner and includes a distal bearing channel 47 and, arranged therein, a bearing element 47 for radial mounting of distal end piece 19 of drive shaft 2. Cavity 47 is, among other things, dimensioned to be sufficiently large so as to allow a compensating axial movement of drive shaft 2.

[0071] A longitudinal section through the proximal coupling module 4 shown in FIG. 1 is diagrammatically represented in FIG. 12, which includes a proximal bearing channel 49 for the proximal end piece 3 of the drive shaft 2, which runs axially through the bearing channel 49 and protrudes axially from the proximal coupling module 4. A bearing element 50 for radial stabilization or mounting of the proximal end piece 3 of the drive shaft 2 is arranged in the bearing channel 49. The sleeve 6 extends axially through this bearing element 50 to its proximal end. In this embodiment, the bearing element 50 serves to radially stabilize and support the sleeve 6 from the outside. In an alternative embodiment, the sleeve 6 does not run through the bearing element 50, but (coming from the distal side) terminates at the distal end of the bearing element 50. In this case, the bearing element 50 is designed, for example, as a sliding or roller bearing. The proximal end piece 3 can be reinforced by a reinforcing material 30, as can the distal end piece 19, especially in the axial section where the drive shaft emerges from a bearing channel 49 or is mounted by bearing elements 50. The bearing elements 40, 41, 42, 48 and 50 are preferably made of zirconium oxide (preferably in a form stabilized with yttrium), aluminum oxide, ceramic or the same material as the wires 35, 36 of the drive shaft 2.

[0072] Furthermore, the coupling housing 4 comprises a channel 51 for the supply and discharge of a lubricant, the channel 5 being connected in a fluid-leading manner to the bearing channel 49 and to the intermediate space between the sleeve 6 and the drive shaft 2. According to a sixth aspect of the invention, the intermediate space or intermediate gap between the drive shaft and the sleeve is filled with a lubricant, which is biocompatible and preferably also physiological. The lubricant is biocompatible, which is the case in this example, distilled water, but it could also be a physiological saline solution or a glucose solution.

[0073] The coupling element 5 of the drive shaft 2 is designed to be as rigid as possible and is connected to the proximal end piece 3 of the drive shaft 2 in a manner that is fixed with respect to rotation, traction, and compression. The coupling element 5 of the drive shaft and the coupling element 17 of the drive motor 18 (designed in this example as a receiver for the coupling element 5) each include axial sliding surfaces 52 and 53 that correspond to one another to form a rotationally fixed but axially displaceable connection. These sliding surfaces run parallel to the longitudinal axis of the respective coupling elements 5 and 17 and do not change shape along the longitudinal axis of the respective coupling elements 5 and 17. In this example, for the coupling element 5 of the drive shaft 2, this is the case with a square end.

[0074] The sheath 7 may be made entirely or at least partially of plastic, for example polyurethane, especially carbothane or urethane, and preferably has a metal reinforcement, which may be made, for example, of an alloy proposed for the drive shaft, thus for example MP35N®.

[0075] 13 and 14 show in each case a schematic perspective view of an example embodiment of the first bearing element 41 of the thrust bearing 44 shown in FIG. 9. The sliding surface 46 of each bearing element 41 comprises a profiling 55, which, by interaction with the lubricant, causes the two sliding surfaces 45, 46 to form a hydrodynamic sliding bearing; by such means the wear volume of the sliding surfaces 45, 46, or of the two bearing elements 40, 41, can be significantly reduced. In the embodiment shown here, the profiling 55 of each sliding surface 46 comprises several protrusions 56 and recesses 57. In the example shown in FIG. 13, there are exactly 12 protrusions and 12 recesses, and in the example shown in FIG. 14, there are exactly 8 protrusions and 8 recesses, the protrusions 56 and recesses 57 being in each case uniformly distributed and arranged over the sliding surface 46 along the circumferential or circumferential direction of the respective sliding surface 46 (in each case indicated by the arrow marked U in the figures) and designed as an alternating sequence of ribs and grooves.

[0076] These ribs and grooves extend in each case from an inner edge 58 of the respective sliding surface 46 facing the drive shaft 2 to an outer edge 59 of the respective sliding surface 46 facing away from the drive shaft 2. In the example shown in Figure 13, the ribs have in each case a height of approximately 0.06 mm (corresponding to the depth of each laterally adjacent groove) and an average width (measured in the circumferential direction U) of approximately 0.2 mm. In the example shown in Figure 13, the protrusions 55 designed as ribs have in each case a maximum height of approximately 0.1 mm, and each protrusion has a leading surface 60 and a trailing surface 61, the leading surface 60 advancing relative to the trailing surface 61 upon rotation of the bearing element 41 in a specified rotational direction along the circumferential direction U (clockwise, assuming a view from the distal end 9 of the catheter 1).

[0077] This leading surface 60 is inclined or beveled relative to the longitudinal axis of the bearing element 41, so that the protrusions 56 decrease or taper upward (i.e., toward the opposite sliding surface 45 of the second bearing element 40, and thus, in this example, distally). Thus, essentially, over any other example embodiment of the profiling of the bearing element 41, a more uniform lubricant bow wave can be achieved, and thus a more stable lubricant film can be formed by such an inclined or beveled leading surface 60. On its respective upper side 62, each of the protrusions 56 has an average width (measured in the circumferential direction U) of about 0.3 mm, with the width of the protrusions 56 increasing radially. In this example, the average width (measured in the circumferential direction U) of the grooves 57 is about 0.1 mm, with the groove width also increasing radially outward. The embodiment shown in Figures 13 and 14 can be manufactured, for example, by means of a (cutting) laser.

[0078] The dependence between the material properties yield point, tensile strength, elongation at break, and cold work hardening, based on the specifications of the manufacturer Fort Wayne Metals, is illustrated using the example of material 35NLT in Figures 16 and 17. This example shows that different heat treatment conditions and work hardening of materials can generally lead to very different material properties.

[0079] For example, if the drive shaft 2 and / or sleeve 6 of the example embodiment shown in Figures 1 to 15 is made of 35NLT, the work hardening of this material is preferably about 35% to 70%, particularly preferably 50% to 60%, so that a tensile strength of about 2000 MPa to 2200 MPa, e.g., 2068 MPa, is achieved without falling short of the 3.5% elongation at break standard. [Explanation of symbols]

[0080] 1 catheter, 2 drive shaft, 3 proximal end piece of drive shaft, 4 coupling module, 5 coupling element of drive shaft, 6 sleeve, 7 sheath, 8 proximal end of catheter, 9 distal end of catheter, 10 pump head, 11 pump casing, 12 downstream tubing, 13 termination housing, 14 support element, 15 lock, 16 blood pump component, 17 coupling element of drive motor, 18 drive motor, 19 distal end piece of drive shaft, 20 pump rotor, 21 puncture site, 22 femoral artery, 23 aortic arch, 24 left ventricle, 25 heart, 26 medial wall, 27 aortic valve, 28 aorta, 29 cavity, 30 reinforcing material, 31 drive shaft winding, 32 3. Winding of the drive shaft, 33. Coaxial layer of the drive shaft, 34. Coaxial layer of the drive shaft, 35. Wire of the drive shaft, 36. Wire of the drive shaft, 37. Winding of the sleeve, 38. Flat tape, 39. Inner surface of the sleeve, 40. Bearing element, 41. Bearing element, 42. Bearing element, 43. Braiding, 44. Thrust bearing, 45. Sliding surface, 46. Sliding surface, 47. Bearing channel of the end housing, 48. Bearing element, 49. Bearing channel of the coupling module, 50. Bearing element, 51. Channel for lubricant, 52. Sliding surface, 53. Sliding surface, 54. Edge, 55. Profiling, 56. Protrusion, 57. Recess, 58. Inner edge, 59. Outer edge, 60. Leading surface, 61. Trailing surface.

Claims

1. A flexible catheter (1) comprising a drive shaft (2), a sleeve (6) surrounding the drive shaft (2), and a sheath (7) surrounding the drive shaft (2) and the sleeve (6), The drive shaft (2), the sleeve (6), and the sheath (7) are flexible; A flexible catheter (1), wherein the drive shaft (2) includes a coupling element (5) at the proximal end of the drive shaft (2) for connecting the drive shaft (2) to a drive motor (18), the drive shaft (2) includes a cavity (29) extending axially through the drive shaft (2) and a plurality of coaxial windings (31, 32) running helically around the cavity (29) of the drive shaft (2); the drive shaft (2) includes a pump rotor (20) at a distal end of the drive shaft (2), the pump rotor (20) being fastened onto the outer periphery of the drive shaft (2) in a rotatably fixed manner; A flexible catheter (1).

2. A catheter (1) according to claim 1, The windings (31, 32) are arranged in two or more coaxial layers (33, 34) on the drive shaft (2). A catheter (1).

3. A catheter (1) according to claim 2, The windings (31, 32) in different coaxial layers (33, 34) have opposite winding directions. A catheter (1).

4. A catheter (1) according to claim 3, The coaxial layers (33, 34) of the drive shaft (2) include an inner layer and an outer layer; When the drive shaft is in a straight state, axially adjacent windings of the inner layer (33) are in contact with each other; Axially adjacent windings of the outer layer (34) do not contact each other. A catheter (1).

5. A catheter (1) according to claim 4, and when the drive shaft is in a straight state, axially adjacent windings in the outer layer have an axial distance in the range of 0.018 mm to 0.042 mm. A catheter (1).

6. A catheter (1) according to claim 4, and when the drive shaft is in a straight state, axially adjacent windings in the outer layer have an axial distance in the range of 0.027 mm to 0.033 mm. A catheter (1).

7. A catheter (1) according to claim 1, the windings (31, 32) are formed by at least one wound wire of the drive shaft (2); A catheter (1).

8. A catheter (1) according to claim 7, the at least one wire has a diameter in the range of 0.09 mm to 0.21 mm; A catheter (1).

9. A catheter (1) according to claim 7, the at least one wire has a diameter in the range of 0.135 mm to 0.165 mm; A catheter (1).

10. A catheter (1) according to claim 7, the windings (31, 32) are arranged in two or more coaxial layers (33, 34) on the drive shaft (2); The drive shaft (2) comprises 1 to 8 wires in each layer. A catheter (1).

11. A catheter (1) according to claim 10, The drive shaft (2) comprises 4 to 6 wires in each layer; A catheter (1).

12. A catheter (1) according to claim 7, the at least one wire is composed of an alloy containing in each case at least 10% by weight of chromium, nickel, and cobalt; A catheter (1).

13. A catheter (1) according to claim 12, the alloy contains 30% to 40% by weight of nickel, 30% to 40% by weight of cobalt, and / or 15% to 25% by weight of chromium; A catheter (1).

14. A catheter (1) according to claim 12, With respect to the weight composition of at least nickel, cobalt and chromium, the alloy corresponds to the material MP35N® or the material 35NLT® or differs therefrom in each case by less than 3% by weight. A catheter (1).

15. A catheter (1) according to claim 12, The alloy has a strength of 1800 N / mm ２ to 2400N / mm ２ and has a tensile strength between A catheter (1).

16. A catheter (1) according to claim 12, The alloy has a strength of 2034 N / mm ２ to 2241 N / mm ２ and has a tensile strength between A catheter (1).

17. A catheter (1) according to claim 1, The winding of the drive shaft (2) is formed by cold forming or work hardening. A catheter (1).

18. A catheter (1) according to claim 1, The surface of the drive shaft (2) has an RZ roughness between 0.01 μm and 1 μm. A catheter (1).

19. A catheter (1) according to claim 18, The RZ roughness of the surface of the drive shaft (2) is between 0.1 μm and 0.8 μm. A catheter (1).

20. A catheter (1) according to claim 1, The outer diameter of the drive shaft is in the range of 0.53 mm to 1.32 mm. A catheter (1).

21. A catheter (1) according to claim 20, The outer diameter of the drive shaft is in the range of about 0.79 mm to about 0.97 mm. A catheter (1).

22. A catheter (1) according to claim 1, At least one axial section of the cavity (29) of the drive shaft (2) is filled with a reinforcing material (30) to reinforce the drive shaft (2) in the respective axial section. A catheter (1).

23. A catheter (1) according to claim 22, The reinforcing material (30) comprises a stainless austenitic steel. A catheter (1).

24. A catheter (1) according to claim 1, The distal end piece (19) of the drive shaft (2) is reinforced; A catheter (1).

25. A catheter (1) according to claim 24, The reinforced distal end piece (19) has a length between 10 mm and 60 mm. A catheter (1).

26. A catheter (1) according to claim 25, the length of the reinforced distal end piece (19) is between 20 mm and 50 mm; A catheter (1).

27. A catheter (1) according to claim 24, the pump rotor (20) is fastened in a rotatably fixed manner onto the outer periphery of the reinforced distal end piece (19) of the drive shaft; A catheter (1).

28. A catheter (1) according to claim 27, the cavity of the drive shaft (2) extends into the drive shaft (2) along the entire longitudinal extent of the drive shaft (2); A catheter (1).

29. A catheter (1) according to claim 1, the sleeve (6) is designed as a bearing coil with a number of windings (37) running helically around the drive shaft (2) in the axial direction, A catheter (1).

30. 30. A catheter (1) according to claim 29, The bearing coil is a wound flat tape (38). A catheter (1).

31. 30. A catheter (1) according to claim 29, The winding direction of the windings (37) of the bearing coil is opposite to the winding direction of the outer layer windings of the windings of the drive shaft (2). A catheter (1).

32. A blood pump arrangement (16), characterized in that it comprises a catheter (1) according to any one of claims 1 to 31.

33. 33. A blood pump arrangement (16) according to claim 32, comprising: the blood pump arrangement (16) further comprises a drive motor (18), and a rotatably fixed and axially displaceable connection exists between the drive motor (18) and the coupling element (5) of the drive shaft (2); A blood pump assembly (16) characterized in that:

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