Catheter pump arrangement and flexible shaft arrangement with a cable core

p0001The invention is in the field of mechanical engineering and is specifically concerned with the transfer of movements and torques via flexible shafts.

p0002Such flexible shafts allow for certain applications, the transmission of torque, for example in hard to reach places, such. As for DIY tools or for dental applications where machining tools must be introduced into a patient's mouth. In general, offer little flexible shafts for use in the medical field, for example, to power micropumps, such as heart catheter pump which are introduced into a body to promote the body's own fluids, or for use in micro-milling, the removal of tissue or deposits can be used.

p0003There are various problems with the operation of such flexible shafts, especially at high speeds, known, one of these problems is that a loud noise on the one hand and mechanical beating with consequent high wear can be caused by imbalance or other mechanical irregularities. Moreover, often with the smallest possible diameter of such flexible shafts to transmit the highest possible torque at low mass of the shaft, which is often difficult to reconcile with the desire for tight bending radii.

p0004Various proposals are known to further such flexible shafts from the prior art. For example, German Offenlegungsschrift<patcit id="pcit0001" dnum="DE10113208A1"><text>DE 101 13 208 A1</text></patcit> shows that with a hollow shaft, which is in the form of a wound spring coil, individual windings are omitted so as to vary the stiffness of the shaft over the length. This is overall better flexibility can be achieved, and in addition to irregular rotations and vibrations are avoided.

p0005From the <patcit id="pcit0002" dnum="DEOS4208221A1"><text>DE-OS 42 08 221 A1</text></patcit> is basically a two oppositely wound spring wire coil hollow shaft known which can transmit torque in both directions of rotation.

p0006From the <patcit id="pcit0003" dnum="DEOS2908143A"><text>DE-OS 29 08 143</text></patcit> is a wave known wound monofilament strands and having a uniform stiffness along their length.

p0007The <patcit id="pcit0004" dnum="US5108411A"><text>US Patent 5,108,411</text></patcit> discloses a shaft which is divided with respect to their length into several sections, one of which has at least one hollow shaft-like structure, wherein the hollow shaft-like section a massive shaft portion is connected. In this way it is achieved that the wave divides into flexible and less flexible longitudinal sections. The flexible shaft sections consist of a coil-like double layer wound in opposite directions hollow shaft.

p0008From the <patcit id="pcit0005" dnum="US20080306327A"><text>US 2008/0306327</text></patcit> is a flexible shaft for the rotating operation known, which consists of influencing the vibration behavior, either from different, consecutively arranged in a row segments of a strand-like element with external patch reinforcing sleeves or from a wound coil with the length varying mechanical properties.

p0009The present invention is in the light of the prior the art the object to provide the lowest possible constructive means a heart catheter pump arrangement with a shaft assembly and a flexible shaft arrangement which opposes a mechanical swinging and hitting the shaft as well as corresponding noise resistors.

p0010The object is achieved according to the invention having the features of claim 1. Here a heart catheter pump arrangement with a blood pump and a shaft assembly with a flexible, rapidly rotating shaft having a drive end and a drive end and steady between the ends of outer diameter is provided with respect to the shaft in at least two different, integrally contiguous axial sections by additional reinforcing body having different sized stiffness and / or flexibility.

p0011This may for example be realized such that the stiffness of the shaft from the end portion which is adjacent to the output end of the pump head and / or pump rotor, in continuously decreases toward the proximal end of the shaft towards at least one step or.

p0012Under the stiffness is understood the resistance, which is opposite to a bending of the shaft. The flexibility also includes the feature of wave ever to be bendable below a certain bend radius.

p0013Different stiffness / flexibilities can be realized by different cross sections of the shaft, different material properties or the gain by intervening in the shaft reinforcement elements. Such reinforcing elements may be inserted in sections, for example in a hollow shaft.

p0014For a flexible shaft assembly is provided that the shaft arrangement has a continuous flexible shaft having between a drive side and a driven side end of at least one cavity, wherein the shaft is partially enhanced by extending in a cavity soul.

p0015In the reinforced by the soul sections the flexibility of the shaft assembly is lower than in the non-reinforced by the soul portions, and accordingly no small bending radii can be achieved at a bending stress in the portions with a soul. In exchange, the rigidity and stability of the shaft assembly is improved in these areas. Because of the positioning of the hollow shaft sections in which runs a soul, the stiffened sections can be freely selected / positioned, with the shaft arrangement, a design can be achieved, the achieved in accordance with the requirements in specific cases where you want them a stiffer waveform as in other places and in certain other sections of sharp bends, ie small bending radii permits.

p0016There may be one or more sections along the shaft assembly, in each of which a soul, said the souls are spaced apart axially. In the reinforced by a soul sections respectively identical soul portions may be provided or different sections soul.

p0017Each of the soul sections along its length can have a stiffness profile, for example, at least one end, at which the respective core is flexible increasingly. This kinking of the hollow portions of the shaft is avoided on the end of a soul and perpetuates the stiffness profile. The shaft can be completely constructed as a hollow shaft

p0018It can advantageously be provided that the soul is rotating in the area, it extends over which, with the shaft.

p0019The respective soul can precisely fit into the hollow shaft sections, so that the deflection power transmission takes place directly and thus absorbs the soul even at large bending radii forces. In this case, it is useful if each soul rotates with the shaft to generate no friction losses.

p0020The soul or the respective core portion may also transmit torque. For this purpose, it is useful to establish a rotationally fixed connection as possible between the hollow shaft section and the soul. The soul can be pressed for this purpose in the hollow shaft.

p0021The individual soul or the individual soul portion may be advantageously made of multiple stranding of stranding. Through this type of product can be the thickness and flexibility of the soul set as desired, and the soul is largely elastically deformable. The individual stranding may advantageously be designed as wires. Thus, the preparation of the soul is simple and inexpensive.

p0022The shaft can in turn be designed as a hollow shaft in the form of at least one wound coil spring. For example, such a coil spring to be so tightly wound that the turns rest against each other directly. Such hollow shaft is very flexible and yet can transmit torque.

p0023It takes place in such a hollow shaft during a very fast rotational movement no excessive material deformation instead, so that the heat generation as well as the exact amount of rotation in the forming work remain limited. As a wound in a sense coil spring torque in a direction better than transfers in the opposite direction of rotation, it may be advantageous that the hollow shaft consists of two coaxial, wound in opposite directions, nested coil springs. In this case, transmits one of the coil springs in a first direction of rotation the torque optimally, while the other coil spring optimally transmits in the opposite direction of rotation. Nevertheless, there is a great flexibility for bending. The two coil springs can be nested in one another such that the larger coil spring surrounds the smaller coil spring directly in the press fit. Thus the mechanical play is minimized in both the axial direction and in the direction of rotation.

p0024The soul may be advantageous fixed at least at one point on that inside the hollow shaft portion. This reliably prevents a shift of the soul in the axial direction. The compound may be prepared, for example by soldering or welding.

p0025The invention is characterized in that the core portions are held inside the hollow shaft by at least one axial spacers. This can determine the distance of each soul section at the end of the hollow shaft and the shaft assembly and / or the distance between two sections soul.

p0026The respective spacer has a smaller diameter than the soul. This ensures that the / spacers afford no amount to an unwanted stiffening of the shaft assembly in the areas where no reinforcement is provided by a soul.

p0027Particularly advantageously, the spacers may be formed as a thread. In this case, it makes sense that the thread is attached to both ends of the shaft arrangement and that individual soul sections are set to the thread in the axial direction. The thread itself does not transmit torque, and it contributes nothing to the stiffness of the shaft assembly.

p0028This allows the desired stiffness and flexibility sections personal preferences in the shaft assembly. By positioning individual soul sections on a thread of the shaft assembly can be in the short term to adjust the positioning of the stiffened portions of the flexible shaft assembly during use.

p0029Can advantageously be provided in the shaft assembly according to the invention that the shaft assembly having a distal, output-side end for connecting a driven unit and a proximal, drive-side end for connection to an engine and that adjacent the distal end of a soulless hollow shaft portion is provided.

p0030Such a design is particularly advantageous when the distal end to be bent particularly strong and low resistance, for example, in medical applications where the actual unit sits at the head of a catheter and thus the distal end of the shaft assembly and handling procedures as flexible as possible be have to be. For example, can be arranged at the end of the shaft assembly, a heart pump, which must be passed through an aortic arch.

p0031The proximal portions of the shaft assembly can then be relatively rigid as they are guided through stretched extending blood vessels. In these areas, a certain stiffness of the shaft assembly is more important than the flexibility.

p0032However, it can also be provided advantageously, the distal (driven side) end portion, in particular the immediately adjacent to a connected to be driven unit area, for example, at least the last 1%, 5% or 10% of the length of the wave train stiffer than the average of the total length the shaft or at least of this area starting to reduce the stiffness of the shaft continuously or in steps toward the proximal end.

p0033Thus the good runout is achieved in the end.

p0034In this case, the shaft assembly to a hollow catheter surrounding the hollow shaft to protect the shaft assembly as a whole and to shield against external influences. Inside the hollow catheter may be provided for the shaft, for example, a coolant and lubricant.

p0035A particularly advantageous application of the invention provides medical equipment of a heart catheter pump arrangement in front with a flexible shaft assembly as described above.

p0036In the following the invention with reference to an embodiment shown in a drawing and described below.

p0037It shows<dl id="dl0001"><dt>Fig. 1</dt><dd>a shaft assembly according to the invention in a three-dimensional representation with several enhanced by a soul waste cut,</dd><dt>FIG. 2</dt><dd>a cross-section of the shaft assembly from <figref idrefs="f0001">Fig. 1</figref>.</dd><dt>Fig. 3</dt><dd>another embodiment of Wellenan- order in a schematic representation,</dd><dt>Fig. 4</dt><dd>an embodiment of the shaft assembly according to the invention in a bent form and</dd><dt>Fig. 5</dt><dd>the application of the wave inventive arrangement with a heart pump.</dd></dl>

p0038The <figref idrefs="f0001">Fig. 1</figref> shows a three-dimensional view of a hollow shaft, which consists of two counter-wound coil springs 1, 2, of which the first light, the second dark is shown. The oppositely directed winding of the two coil springs causes in each rotational direction one of the springs is compressed, and the other is stretched. Thus, a total of no deformation takes place in the axial direction depending on the direction of rotation instead, to be transmitted.

p0039The density of the windings of the individual springs, and the strength of the spring wire on the one hand determine the flexibility or stiffness of the hollow shaft, on the other hand, the transmissible torque.

p0040There are still in the <figref idrefs="f0001">Fig. 1</figref> two soul sections 3, 4 shown, which stiffen the shaft assembly in each of the axial sections 5. 6 In the intervening axial 7 the hollow shaft remains free and is there correspondingly flexible.

p0041The soul sections 3, 4 can be configured as a massive body, such as a plastic or metal body, which have a high resilience and breaking strength and a high fatigue resistance.

p0042However, the soul sections can be designed as a stranded souls who then, consist of a plurality of twisting elements, for example wires. This embodiment is illustrated by the<figref idrefs="f0001">FIG. 2</figref> shown, where a section showing the radial arrangement of the two coil springs 1, 2 as well as the soul. 3 It is there also shown that the core 3 consists of a plurality of stranded elements 8, 9, making it very flexible and permanently deformed.

p0043The two coil springs 1, 2 are dimensioned and arranged such that they are mutually joined in a press fit radially nested coaxially, so that takes place between them a distribution of the torque to be transmitted. In addition, bending stresses are taken jointly by both coil springs. The corresponding loads are detailed in sections, in which a soul within the cavity of the coil springs 1, 2 is, by this soul are also recorded, as it is tightly fitted into the cavity.

p0044Based on <figref idrefs="f0001">Fig. 3</figref> it is shown that the soul portions each having a tapering tapered end, whereby the end portion 10, 11 of the core 3 to the end will be more flexible. This stiffness is not abruptly reduced to the measure of the stiffness of the hollow shaft in the overall consideration of the shaft assembly to the end of each soul portion, but there is a continuous transition instead, which leads at a bending stress of the shaft assembly to a continuous distribution to buckling stresses and the risk to reduce the breakage of the shaft assembly.

p0045As a result, at a given bending stress, the bending radius in sections 5, 6, in which the hollow shaft is reinforced by a soul or a soul section, significantly enlarged. In the sections where there is no soul, a considerably smaller bending radius is achieved. To avoid kinks between these areas, the design of the end of the soul portions described above is suitable.

p0046In the <figref idrefs="f0002">Fig. 4</figref> is an example of a bent shaft assembly shown in accordance with the invention in which two souls are shown 3, 4 in sections 5, 6, the virtually straight path and have a large bending radius. Particularly in the section 7 the hollow shaft assembly is severely bent, as well as in the section 12th

p0047The gradual transition of rigidity through appropriate design of the ends of the souls 3, 4 in the areas 10, 13 causes there the risk of buckling is reduced.

p0048Between the souls 3, 4 are in the <figref idrefs="f0002">Fig. 4</figref> exemplified spacer, as well as between the core 3 and the drive-side end of the shaft assembly. The spacers are designated 14, 15 and can be designed as a more or less stiff, thin souls which have a substantially smaller diameter than the souls 3, 4 and also a substantially lower stiffness. However, the spacers 14, 15 may be formed only as a thread with negligible stiffness easy, with serving in this case to fix the spacer to both ends of the hollow shaft arrangement suited to the soul sections 3, 4 curious how on a chain and at predetermined intervals to keep stable.

p0049This embodiment has the advantage that in the existing hollow shaft depending on the requirements of the distribution of different stiffness along the hollow shaft arrangement, a number of souls / soul sections can be drawn with spacers, wherein the length of each spacer is individually adaptable to the intended use of the shaft assembly.

p0050The <figref idrefs="f0002">Fig. 5</figref> shows schematically an application of the shaft assembly according to the invention, wherein the shaft assembly, there is illustrated only schematically and designated by 16. The shaft assembly 16 on the drive side connected to a motor 17 and extends in a hollow catheter 18 insertable and introduced over the way this blood vessel into a heart chamber 20 into a blood vessel 19 of a body, such as a human body.

p0051At the end of the hollow catheter 18 is a heart pump 21, which is executed as an axial pump and in its interior has a rotor which is driven by means of the shaft assembly 16 at high speeds, for example, between 10,000 and 20,000 rpm.

p0052The advantages of the wave device according to the invention indicated by the fact that on one hand the shaft arrangement is well inserted by appropriate stiffer areas through the blood vessel 19, but that seen in the distal region of the concrete placement of, say in the region of the aortic arch facing the ventricle, a high flexibility of shaft arrangement is provided so that there the heart pump 21 is introduced into the heart chamber, without the rigidity of the shaft assembly and the hollow catheter injury of the heart chamber walls or aorta can result in the region of the aortic arch. By appropriate distribution of the soul (s) along the shaft assembly includes a shaft and hitting the acoustic resonance is reliably prevented.