Cannula for intravascular blood pump

Abstract

To provide an improved method of manufacturing a cannula for an intravascular blood pump.SOLUTION: A method of manufacturing a cannula (4) for an intravascular blood pump comprises the steps of forming a first axial section (13) and a second axial section (15) of an elongate tubular body of the cannula (4) by dispensing a first liquid material and a second liquid material, respectively, onto a mandrel (7) by means of at least one dispenser (8). The mandrel (7) is rotated and the dispenser (8) moves relative to the mandrel (7) in an axial direction during dispensing of the liquid materials. The first and second axial sections (13, 15) are formed so as to have different bending stiffness. The first and second liquid materials are dispensed onto the mandrel (7) such that the first and second liquid materials blend into each other to form a smooth transition area (14).SELECTED DRAWING: Figure 3a

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a cannula for an intravascular blood pump for percutaneous insertion into a patient's blood vessel, and to a cannula obtainable by the above method.

Background Art

[0002] An intravascular blood pump is used to assist the function of a patient's heart either as a left ventricular assist device (LVAD) or a right ventricular assist device (RVAD). An intravascular blood pump for percutaneous insertion typically includes a catheter and a pump device and is inserted into the patient's heart through the aorta into the left ventricle. The pump device includes a blood inlet, a blood outlet, and a cannula, and the blood flow through the cannula is created, for example, by a rotor of the pump device. For example, the cannula may extend through the aortic valve, a blood inlet is disposed at the distal end of the cannula in the left ventricle, and a blood outlet is disposed at the proximal end of the cannula in the aorta.

[0003] Cannulas may be relatively soft and flexible, such as those made of silicone, soft polyurethane, or polyester (Dacron®), to reduce the risk of damaging heart valves. However, if a very soft cannula is connected to, for example, a metal pump housing, the cannula material at the interface between the pump housing and the cannula may crack due to the high load the interface is subjected to. There is also a high risk of thrombi forming within the cracks in the material, and if these cracks separate from the blood pump and are transported by the vascular system, they can injure the patient. Harder cannulas may be made of, for example, rigid polyurethane. However, if the cannula is too hard, its lateral movement within the heart valve may damage the valve lobes. It is also known that the strength of soft cannulas can be increased by incorporating a helical wire, such as a nitinol wire. However, this may cause a pinching effect at the interface between the pump housing and the cannula, and thus damage the cannula material. Thus, from the aforementioned perspective, the cannula must be soft enough to avoid damage to the heart valve, but also rigid enough to avoid damage to the material. [Overview of the project] [Problems that the invention aims to solve]

[0004] The object of the present invention is to provide an improved method for manufacturing cannulas for intravascular blood pumps that have high rigidity against load-bearing capacity during operation of the blood pump without causing injury to the patient's body. [Means for solving the problem]

[0005] The objective is achieved in accordance with the present invention by a method for manufacturing a cannula for an intravascular blood pump having the features of an independent claim, and by a cannula that can be obtained by such a method. Preferred embodiments and further developments of the present invention are specified in the dependent claims. Throughout this disclosure, the term “distal” refers to a direction away from the user and toward the heart, while the term “proximal” refers to a direction toward the user.

[0006] Broadly speaking, according to the present invention, a cannula for an intravascular blood pump is manufactured by dispensing a liquid material onto an elongated element such as a shaft. Preferably, the liquid material is applied in layers that dry or harden to form different axial sections of the elongated tubular body of the cannula. The shaft is removed after the body is completed. This method allows for adjustment of the cannula's properties, such as bending stiffness, along its length. Rather than attaching the different axial sections to each other by, for example, welding, bonding, or adhering, the axial sections of the cannula of the present invention are created by dispensing the liquid material onto the shaft so that they blend smoothly with each other, although distinct boundaries cannot be determined between the axial sections. Therefore, material boundaries that could generate high stress during the operation of the blood pump can be avoided.

[0007] More specifically, according to one embodiment, the method includes the step of dispensing a first liquid material onto a shaft using at least one dispenser, and simultaneously forming a first axial section of the cannula body by the shaft and dispenser moving relative to each other in the axial and circumferential directions of the shaft. The method further includes the step of dispensing a second liquid material onto a shaft using at least one dispenser, and forming a second axial section by the shaft and dispenser moving relative to each other in the axial and circumferential directions of the shaft.

[0008] The first and second liquid materials are dispensed onto a shaft such that they mix with each other to form a transition region. For example, the transition region may extend over an axial length of at least 10 μm to provide a smooth transition between the first and second axial regions. The first and second axial regions are formed to have different bending stiffnesses. The first and second materials may be dispensed by a single dispenser or by different dispensers. If only one dispenser is used, the first and second materials may be dispensed by a single nozzle or by different nozzles of the dispenser.

[0009] As stated above, it should be understood that the method preferably further includes a step of curing or drying the dispensing layer of liquid material to form the final product. In particular, the material may be at least partially dried or cured before the next layer of liquid material is dispensed. The liquid material may be a material comprising a solvent, molten material, extruded material, or the like, having a viscosity suitable for dispensing the material onto a rotating mandrel, as will be described in more detail below. In particular, one or more materials of the cannula may be polymer materials.

[0010] In other words, the cannula that can be obtained by the method described above has an elongated tubular body with a blood inlet and a blood outlet, the body comprising a first axial section containing a first material and a second axial section containing a second material, the first and second axial sections having different bending stiffnesses, and the first and second materials being mixed with each other in a transition region. The cannula may have three or more axial sections having different bending stiffnesses. For example, one or more bent sections having low bending stiffness may be created, which connect to a stiffer axial section having greater bending stiffness. The length of the axial sections may be selected as desired, for example, depending on the application. For example, the bent sections may be shorter or longer than the stiffer sections.

[0011] In one embodiment, first and second liquid materials are dispensed onto a mandrel to form a first wall thickness in a first axial section and a second wall thickness in a second axial section, respectively, where the first wall thickness is different from the second wall thickness. Alternatively, or additionally, the first and second liquid materials may be different. Different bending stiffnesses may result from at least one of different wall thicknesses and different materials. Throughout this disclosure, the term “wall thickness” and the respective values ​​given for wall thickness refer to the final state of the cannula, i.e., after curing or drying of the material, unless otherwise indicated.

[0012] If the first and second materials are different, they may overlap axially in the transition region. Suitable materials are flexible polyurethane, rigid polyurethane, polyethylene, silicone, or similar. It should be understood that the first and second materials may be identical. Instead of overlapping, the materials may be mixed with each other, regardless of whether they are identical or different. The wall thickness may be affected by various parameters such as the material, the amount of material dispensed, the dispensing rate, the speed of movement of one or both of the mandrel and dispenser, and the proportion of solvent in the material, as will be described in more detail below. Thus, the properties of the first and second axial regions, in particular the bending stiffness, can be adjusted as desired.

[0013] The first axial segment may be the most proximal or most distal segment of the cannula body and may have greater bending rigidity than the second axial segment or the rest of the cannula body. In particular, the segment connected to the pump housing may have greater bending rigidity than the rest of the cannula body. This provides sufficient strength at the interface between the cannula and the pump housing, and at the same time provides the cannula with flexibility to avoid damage to surrounding tissues such as heart valves.

[0014] As described above, the mandrel and dispenser move relative to each other axially and circumferentially around the mandrel during the dispensing of liquid material onto the mandrel. This can be achieved by rotating the mandrel around its longitudinal axis, for example on a lathe, and moving the dispenser axially along the mandrel while dispensing the first and second liquid materials. The mandrel is preferably rotated at a speed of about 10-15 rpm (revolutions per minute), more preferably about 12 rpm. It should be understood that the dispenser may alternatively be fixed axially, and the rotating mandrel may move axially. For example, if the liquid material is sprayed onto the mandrel, it may also be possible to move the dispenser circumferentially around the mandrel. Those skilled in the art will understand that any combination of axial and circumferential movement or rotational movement of the mandrel and dispenser may be suitable for achieving the desired relative motion between the mandrel and the dispenser. Preferably, the mandrel has a circular cross-section, but other cross-sections are also possible. The core may have a length of approximately 1 cm to 40 cm, resulting in a cannula with a length of approximately 1 cm to 40 cm. The core may have a diameter of approximately 1 mm to 10 mm, resulting in a cannula with an inner diameter of approximately 1 mm to 10 mm.

[0015] The method further includes the step of forming a base layer extending along the entire length of the cannula body by dispensing a third liquid material onto a shaft. The base layer is preferably formed by dispensing a substantially uniform amount of the third liquid material relative to the length of the shaft, and the base layer preferably has a thickness of about 50 μm to 100 μm. The third material may be different from the first and second materials, or it may be identical to at least one of the first and second materials. The base layer may be provided to create a uniform support for the tubular body of the cannula, while the properties of the first and second axial regions are regulated by subsequent layers of the first and second materials applied on the base layer. Other specific layers or axial regions having specific properties may be included in the cannula. For example, a region for enhanced metal adhesion may be created by providing a primer layer. One or more layers may be provided with a drug such as heparin to avoid plug formation on the surface of the cannula body.

[0016] The method further includes the step of forming a stiffening structure by dispensing a fourth liquid material, preferably a polymer material, onto a core, the first and second liquid materials being dispensed both before and after dispensing the fourth material to embed the stiffening structure into the body of the cannula. The stiffening structure may be formed along a helical path or may be any other suitable structure, such as longitudinal or circumferential pillars or lattice structures. The fourth material preferably has a higher Young's modulus (elastic modulus) than the first and second materials in order to provide sufficient strength to form the stiffening structure. For example, the fourth material of the stiffening structure may be rigid polyurethane, while the first and second materials may be flexible polyurethane, polyethylene, or silicone. This means that the elongated tubular body of the cannula may contain an embedded stiffening structure made of a plastic material, rather than embedding a stiffening structure made of metal. Alternatively, or additionally, the body of the cannula may include a stiffening structure comprising a thread or wire, which may be made of metal, preferably a shape-memory material such as nitinol, or a polymer. The wire may extend in a helical shape around the cannula. If the wire is metal, it may be pre-wound before being added to the cannula. Alternatively, if the thread or wire is made of polymer, for example, it may be wound around a core along a helical path or in another preferred pattern, such as two opposing helical paths intersecting each other, or in another braided pattern. For example, the helical wire may be embedded in the body of the cannula between a layer of the first material and a layer of the second material.

[0017] Advantageously, at least one of the first and second liquid materials contains a solvent that evaporates after the first and second liquid materials are dispensed, respectively, and the proportion of the solvent is at least 70%, preferably at least 80%, and more preferably at least 90%. The proportion of the solvent is preferably measured in volume percent (vol%), but alternatively, where appropriate, it may be measured in weight percent. The solvent preferably evaporates, but alternatively or additionally, may be absorbed by a core, which may be provided with a porous structure for this purpose. The first and second materials may contain the same proportion or different proportions of solvent that mix with each other in the transition region. If the proportions of solvent are different, this will result in different wall thicknesses or respective regions after the solvent has evaporated, i.e., dried.

[0018] Providing a solvent within the liquid material facilitates the production of ultrathin layers, as the majority of the coated material evaporates after dispensing onto the mandrel. This means that a layer of liquid material "physically dries" on the mandrel before another layer of liquid material is dispensed. However, the layer should not be completely dry and cured before the subsequent layer is dispensed in order to ensure that the subsequent layer is sufficiently mixed to form an elongated tubular body. Preferably, at least one of the first and second axial sections is formed by dispensing at least 5, preferably at least 10, and up to 20 layers of the first and second liquid materials, respectively. This can result in a cannula having an elongated tubular body with a wall thickness ranging from about 50 μm to about 500 μm after drying and curing of the material. In general, any number of layers, different materials, axial sections, etc., can be produced as desired. Additional layers may be created by at least partially immersing the cannula produced by the described dispensing method in the liquid material.

[0019] In one embodiment, the spindle may have a circumferential shoulder connecting two axially adjacent portions of the spindle having different diameters, and the two axially adjacent portions of the spindle are preferably separated from each other to remove the cannula from the spindle. Thus, the elongated tubular body of the cannula may have a circumferential shoulder connecting two axially adjacent regions of the body having different diameters.

[0020] The method may further include the step of forming at least one marker to be placed on the body of the cannula, the at least one marker may be visually perceptible, for example, by exhibiting a different color from the body of the cannula, or it may be radiopaque, so as to be visible under X-rays. Preferably, the at least one marker is formed by dispensing a liquid material using a dispenser. The at least one marker may extend on an elongated tubular body or be embedded in an elongated tubular body. For example, the marker may be a colored band extending around the body of the cannula.

[0021] The method may further include the step of forming a lumen extending within the wall of the cannula body by embedding an elongated element into the wall of the cannula body. The elongated element may be a hollow tubular element that remains inside the cannula body to form the lumen. Alternatively, the elongated element may be a solid filament that is removed from the cannula body to form the lumen.

[0022] The method further includes the step of forming at least one hole in the body of the cannula by dispensing a liquid material onto a mandrel, either without optionally rotating the mandrel or while rotating the mandrel very slowly during the dispensing of the liquid material. In particular, the cage structure at one end of the cannula may be formed by dispensing material onto a mandrel, which is similar to a 3D printing process. The viscosity of the material is selected to prevent dripping of the material but to allow fusion with other printed areas or with layers of the cannula body that are dispensed earlier or later. Thus, the structure printed in this manner is attached to the body of the cannula and forms an integral part of the cannula.

[0023] The method may further include the step of attaching a cannula to the housing of a pump device of an intravascular blood pump, i.e., the present invention also relates to an intravascular blood pump for percutaneous insertion into a patient's blood vessel, comprising the cannula obtained by the above method.

[0024] The foregoing summary, as well as the following detailed description of the preferred embodiments, will be better understood when read in conjunction with the accompanying drawings. For purposes of illustration of the present disclosure, reference is made to the drawings. However, the scope of the present disclosure is not limited to the specific embodiments disclosed in the drawings.

Brief Description of the Drawings

[0025] [Figure 1] A diagram showing the heart of a patient in a state where an intravascular blood pump is inserted into the left ventricle through the aorta. [Figure 2] A diagram showing an enlarged view of the interface between the cannula and the housing of the pump device of the intravascular blood pump. [Figure 3a] A diagram showing the steps of a method for manufacturing a cannula. [Figure 3b] A diagram showing the steps of a method for manufacturing a cannula. [Figure 3c] A diagram showing the steps of a method for manufacturing a cannula. [Figure 3d]This diagram shows the steps involved in manufacturing a cannula. [Figure 4a] This figure shows the steps of a method for manufacturing a cannula according to another embodiment. [Figure 4b] This figure shows the steps of a method for manufacturing a cannula according to another embodiment. [Figure 4c] This figure shows the steps of a method for manufacturing a cannula according to another embodiment. [Figure 4d] This figure shows the steps of a method for manufacturing a cannula according to another embodiment. [Figure 5a] This figure shows the steps of a method for manufacturing a cannula according to yet another embodiment. [Figure 5b] This figure shows the steps of a method for manufacturing a cannula according to yet another embodiment. [Figure 5c] This figure shows the steps of a method for manufacturing a cannula according to yet another embodiment. [Figure 5d] This figure shows the steps of a method for manufacturing a cannula according to yet another embodiment. [Figure 6] This figure shows the layers of the cannula before and after solvent evaporation. [Figure 7] This is a diagram showing a cannula with a stiffening structure. [Figure 8] This is a diagram showing a cannula with a label. [Figure 9] This figure shows a cannula on a spindle having a circumferential shoulder portion. [Figure 10] This diagram shows the details of the lumen inside the cannula during the manufacturing process. [Figure 11] This figure shows a perspective view of the 3D printing process for the cannula inlet cage. [Modes for carrying out the invention]

[0026] Figure 1 illustrates a blood pump inserted into a patient's heart H. More specifically, the blood pump comprises a pump device 1 attached to a catheter 10, through which the pump device 1 is inserted into the left ventricle LV of the patient's heart H via the aorta AO, which includes the descending aorta DA and the aortic arch AA. The catheter 10 has a distal end 10a and a proximal end 10b. The pump device 1 has a blood outlet 3 located outside the patient's heart H within the aorta AO, while the blood inlet 2 is in communication with a cannula 4 located inside the left ventricle LV. An impeller (not shown) is provided within the housing 1a of the pump device 1 to induce blood flow from the blood inlet 2 to the blood outlet 3. The distal end of the blood pump is fitted with a soft tip 5, such as a pigtail or J-shaped tip, to facilitate insertion of the blood pump into the patient's heart H without causing any damage to surrounding tissue. The soft tip 5 also helps to keep soft tissue away from the cannula 4.

[0027] Figure 2 shows an enlarged schematic cross-sectional view of the interface 6 between the housing 1a of the pump device 1 and the cannula 4. The housing 1a and the cannula 4 are stepped at their respective ends 22, 23 where they will be fitted together. The housing 1a of the pump device 1 may be made of metal, while the cannula 4 may be made of a plastic material such as silicone, polyethylene, or polyurethane. At the interface 6 between the relatively rigid material of the housing 1a of the pump device 1 and the relatively soft material of the cannula 4, the load during operation of the blood pump may cause cracks in the material of the cannula 4. Therefore, it is desirable to increase the bending stiffness of the cannula 4 in the area of ​​interface 6. However, the rest of the cannula 4 must be softer to avoid damage to surrounding tissues such as the lobes of the heart valve.

[0028] A method for manufacturing cannulas 4 that can exhibit different properties along their length, particularly different bending stiffnesses, is schematically shown in Figures 3a to 3d. The core concept of this method is that the cannula is produced by dispensing a liquid material onto an elongated element such as a spindle, rather than by fitting different sections together. The following steps are schematically shown and not to scale for illustrative purposes. In particular, for simplicity, the steps are shown only for a single layer within each axial section. However, it should be understood that two or more, up to 20 or more layers, may be applied within each axial section.

[0029] In the first step shown in Figure 3a, the base layer 10 is applied onto the mandrel 7. To create the base layer 10, a liquid material is applied onto the mandrel 7 using a dispenser 8 having at least one nozzle 9 for dispensing the liquid material. While dispensing the liquid material, the mandrel 7 is rotated about a longitudinal axis L that coincides with the longitudinal axis L of the cannula 4. The mandrel 7 may be rotated using a suitable device such as a lathe (not shown). The rotational speed may be about 12 rpm. The dispenser 8 is moved axially along the length of the mandrel 7. The axial speed of the dispenser 8 and the rotational speed of the mandrel 7 are selected so that a continuous layer of the liquid material can be applied along the length and around the circumference of the mandrel 7. The final base layer 10, i.e., after drying and curing, may have a thickness of about 50 μm to 100 μm.

[0030] After the base layer 10 has been completely coated onto the mandrel 7 and dried to the desired extent, a layer 11 of liquid material is applied in the same manner as the base layer 10, i.e., by moving the dispenser 8 along the longitudinal direction of the mandrel 7 while rotating the mandrel 7, as shown in Figure 3b. The liquid material of layer 11 may be the same material as the base layer 10, or a different material. The same dispenser 8 may be used. In particular, if the materials are different, the materials may be dispensed by a different nozzle of the dispenser 8, or possibly a different dispenser. Layer 11 is the portion of the first axial section 13 of the cannula 4 (see Figure 3d) and is applied only along the length of the mandrel 7.

[0031] As shown in Figure 3c, another layer 12 of liquid material is applied onto the cannula 7 adjacent to layer 11 in the axial direction by moving the dispenser 8 along the longitudinal direction of the cannula 7 while rotating the cannula 7, in the same manner as described above. The material of layer 12 may be different from the material of layer 11. As shown in Figure 3c, layer 12 is thicker than layer 11. Layer 12 is part of the second axial section 15 of the cannula 4 (see Figure 3d) and is applied only along the length of the cannula 7. Layers 11 and 12 overlap and mix with each other to form a smooth transition region 14 between the first axial section 13 and the second axial section 15, extending over a length of at least 10 μm.

[0032] By appropriately selecting the material and wall thickness of layers 11 and 12, the bending stiffness of the first and second axial sections 13 and 15 can be adjusted as desired. It should be understood that each of the first and second axial sections 13 and 15 preferably includes two or more material layers. In other words, two or more layers 11 and two or more layers 12 are applied onto the mandrel 7 to form the first axial section 13 and the second axial section 15, respectively. In addition, three or more axial sections connected by their respective transition regions may be created on the mandrel 7. For example, to create a cannula with a rigid section connected by a bent section, sections with low bending stiffness may be created to alternate with sections with high bending stiffness. After the desired amount of material has been applied onto the mandrel 7 and has hardened sufficiently, the mandrel 7 is removed from the cannula 4 as shown in Figure 3d.

[0033] Figures 4a to 4d show substantially the same method as Figures 3a to 3d. The only difference is that the material of layer 12 is the same as the material of layer 11. The different bending stiffnesses of the first axial region 13 and the second axial region 15 result from the different wall thicknesses. Figures 5a to 5d show substantially the same method as Figures 3a to 3d. In this embodiment, the materials of layers 11 and 12 are different, but the wall thickness is constant along the length of the cannula 4, i.e., the wall thicknesses of the first axial region 13 and the second axial region 15 are the same. The different bending stiffnesses result from the different materials. As specifically shown in Figure 5d, the different materials of the first and second axial regions 13 and 15 are mixed with each other in the transition region 14. Alternatively, also referring to Figures 5a to 5d, the materials of layers 11 and 12 may be the same, but may contain different proportions of solvent and be mixed with each other in the transition region 14. For example, layer 11 may contain less solvent than layer 12, which will result in different wall thicknesses for layers 11 and 12 (i.e., the first and second axial regions 13 and 15) after curing (not shown).

[0034] Referring now to Figure 6, as briefly explained above, the liquid material preferably contains a solvent. The proportion of solvent in each material may be greater than 80 vol%, preferably greater than 90 vol%. The principle is illustrated in Figure 6 with respect to layer 11. Figure 6 shows layer 11 applied to the mandrel 7 before (left) and after (right) evaporation of the solvent. After evaporation of the solvent, which can also be described as "physically drying," the thickness of the application is reduced by approximately the amount of solvent. Using a high proportion of solvent facilitates the production of ultrathin layers, as most of the applied material evaporates. In other words, a relatively large amount of material can be dispensed, while only a small amount of material remains in the finished cannula 4. This is simpler than applying a small amount without solvent to create a thin layer and does not require as much precision from the dispenser.

[0035] Figures 7–11 show different embodiments of cannula 4, either individually or in any combination. For simplicity, cannula 4 is shown as a single unit in Figures 7–11. However, cannula 4 includes different layers and axial sections, as described above.

[0036] The cannula 4 shown in Figure 7 includes a stiffening structure 16 embedded in the wall of the cannula 4. The stiffening structure 16 may have a helical shape extending around the cannula 4, or it may form any other suitable pattern that reinforces the cannula 4. The stiffening structure 16 may be created by dispensing a liquid material using a dispenser 8. However, rather than creating continuous layers as described above, the liquid material for the stiffening structure 16 is applied onto the mandrel 7 along a helical path. This material is applied on top of the previously created layers and covered by subsequent layers so that the stiffening structure 16 is embedded in the wall of the cannula 4. For example, the stiffening structure 16 may be made of polyurethane, while the surrounding material is polyethylene, which is softer than polyurethane. In particular, the stiffening structure 16 has a higher modulus of elasticity than the rest of the wall of the cannula 4.

[0037] Alternatively, or additionally, the cannula may include a stiffening structure formed of a helical nitinol wire that is pre-wound and incorporated into the cannula 4 during the dispensing process to be embedded in the wall of the cannula 4. Further alternatively, polymer thread may be wound around a core between the material layers of the cannula. As described above, any of the above stiffening structures are advantageously embedded between the layers of the cannula 4. For example, a stiffening structure may follow the application of a first material layer (e.g., liquid material along the path, pre-wound nitinol wire, or polymer thread), and this stiffening structure may then be covered by one or more further material layers. This is illustrated by layers 10 and 11 in Figure 7. It should be understood that the cannula 4 may include more layers than layers 10 and 11 in Figure 7.

[0038] Referring now to Figure 8, the cannula 4 is shown having a label 17 that is visible to the human eye, for example, by exhibiting a different color from the surrounding material, or visible under X-rays, i.e., radiopaque. The label 17 may be coated onto the cannula 4 or embedded in the cannula 4. The label may extend along a helical path or along any other desired path. The label may be manufactured by dispensing a liquid material as described above with respect to the stiffening structure 16. Alternatively, a wire or thread, as described above, may be accompanied by a label. For example, the wire or thread may be radiopaque.

[0039] Figure 9 shows a cannula 4 having a circumferential shoulder portion 18, i.e., the cannula 4 has sections 25 and 26, each of which has a different inner and outer diameter. Thus, the shaft 7 has circumferential shoulder portions 24 connecting two shaft sections 7a and 7b having different diameters. To facilitate the removal of the shaft 7 from the final cannula 4, sections 7a and 7b are separable.

[0040] The cannula 4 shown in Figure 10 has a lumen 19 extending through the wall of the cannula 4. The lumen 19 can be created by incorporating a filament 20 during the dispensing method described above. If the filament 20 is solid, it will be withdrawn from the cannula 4 after the formation of the cannula 4 is complete and the lumen 19 has been formed. Alternatively, a hollow filament may be used that is embedded in the cannula 4 to form the lumen 19.

[0041] The method for manufacturing the cannula 4 may further include the step of creating at least one opening within the cannula 4, for example, the blood inlet 2 described above, as shown in Figure 11. A cage structure 21 or similar may be created using a dispenser 8 to form the opening 2. For this purpose, the shaft 7 is preferably not rotated or rotated very slowly, depending on the desired shape of the cage structure 21. For example, if a longitudinal column is created, the shaft 7 should not be rotated. The viscosity of the dispensing material of the cage structure 21 is selected so that the material does not drip from the shaft 7 but mixes with the previously or subsequently applied layer of the cannula 4 to form a cohesive body.

[0042] A method for manufacturing a cannula, including the dispensing step described above, enables the manufacture of a cannula having adjustable properties along its length, including any desired structure. The functions described above may be included in the cannula individually or in combination. The wall thickness may be affected by various parameters such as the type of material, the amount of material dispensed, the dispensing rate, the speed of movement of one or both of the shaft and dispenser, and the proportion of solvent in the material. It should be understood that any desired number, order, and arrangement of layers may be included in the cannula. Any number, order, and arrangement of axial sections having different properties, such as bending stiffness, may be created as desired. The embodiments described are for illustrative purposes only and are not intended to limit. The present invention is defined in the appended claims.

Claims

1. A method for manufacturing a cannula (4) for an intravascular blood pump for percutaneous insertion into a patient's blood vessel, wherein the cannula (4) has an elongated tubular body with a blood inlet and a blood outlet, and the method is The steps include: dispensing a first liquid material onto a spindle (7) using at least one dispenser (8), and simultaneously, the spindle (7) and the dispenser (8) moving relative to each other in the axial and circumferential directions of the spindle (7) to form a first axial region (13) of the elongated tubular body; The process includes the step of dispensing a second liquid material onto the spindle (7) using at least one dispenser (8), and simultaneously, the spindle (7) and the dispenser (8) moving relative to each other in the axial and circumferential directions of the spindle (7) to form a second axial region (15) of the elongated tubular body, The first and second axial regions (13, 15) are formed to have different bending rigidities, and the first and second liquid materials are dispensed onto the core (7) such that the first and second liquid materials form a transition region (14). The method further comprises the step of dispensing a third liquid material onto the core (7) to form a base layer (10) that extends along the entire length of the body of the cannula.

2. A method according to claim 1, characterized in that the first and second liquid materials are different, and the different bending stiffnesses are derived from different materials.

3. A method according to claim 1 or 2, characterized in that the central rod (7) is rotated about its vertical axis.

4. A method according to any one of claims 1 to 3, characterized in that the dispenser (8) is moved axially along the shaft (7) while dispensing the first and second liquid materials.

5. A method according to any one of claims 1 to 4, characterized in that the base layer (10) is formed by dispensing a uniform amount of the third liquid material relative to the length of the core (7).

6. A method according to any one of claims 1 to 5, further comprising the step of forming a stiffening structure (16) by dispensing a fourth liquid material onto the core (7) in a helical path.

7. A method according to any one of claims 1 to 6, characterized in that at least one of the first and second liquid materials contains a solvent that evaporates after the first and second liquid materials are dispensed, and the proportion of the solvent is at least 70 vol%.

8. A method according to any one of claims 1 to 7, characterized in that at least one of the first and second axial regions (13, 15) is formed by dispensing at least 5, up to 20 layers of the first and second liquid material, respectively.

9. A method according to any one of claims 1 to 8, characterized in that the spindle (7) has a circumferential shoulder portion (24) that interconnects two axially adjacent portions (7a, 7b) of the spindle (7) having different diameters.

10. A method according to any one of claims 1 to 9, further comprising the step of forming at least one label (17) that is placed on the body of the cannula, wherein the at least one label is visually perceptible or radiopaque.

11. A method according to any one of claims 1 to 10, further comprising the step of embedding an elongated element (20) into the wall of the body of the cannula to form a lumen (19) extending within the wall of the body of the cannula.

12. A method according to any one of claims 1 to 11, further comprising the step of forming at least one hole in the body of the cannula by dispensing a liquid material onto the core (7) without rotating the core (7) while dispensing the liquid material.

13. A method according to any one of claims 1 to 12, further comprising the step of attaching the cannula (4) to the housing (1a) of the pump device (1) of an intravascular blood pump.

14. A method according to any one of claims 1 to 13, wherein the cannula (4) has an elongated tubular body with a blood inlet and a blood outlet, the body includes a first axial region (13) containing a first material and a second axial region (15) containing a second material, the first and second axial regions (13, 15) having different bending stiffnesses, and the first and second materials being mixed with each other in a transition region (14), A method characterized in that the cannula (4) further comprises a base layer (10) having a third material and extending along the entire length of the main body of the cannula (4).

15. A method according to any one of claims 1 to 14, wherein the cannula (4) has an elongated tubular body with a blood inlet and a blood outlet, the body includes a first axial region (13) comprising a first material and a second axial region (15) comprising a second material, the first and second axial regions (13, 15) having different bending stiffnesses, the first and second materials being different, and overlapping axially in the transition region (14), A method characterized in that the cannula (4) further comprises a base layer (10) having a third material and extending along the entire length of the main body of the cannula (4).

16. A method according to claim 14 or 15, characterized in that the first axial region (13) has a first wall thickness, the second axial region (15) has a second wall thickness, the first and second axial regions (13, 15) differ in at least one of the material and the wall thickness, and the different bending stiffnesses result from at least one of the different material and the different wall thicknesses.

17. A method according to any one of claims 14 to 16, characterized in that the first axial region (13) is the nearest or most distal region of the body of the cannula and has greater bending rigidity than the second axial region (15) or the remainder of the elongated tubular body.

18. A method according to any one of claims 14 to 17, characterized in that the elongated tubular body includes an embedded stiffening structure (16) made of a plastic material.

19. A method according to any one of claims 14 to 18, characterized in that the elongated tubular body includes a helical wire.

20. A method according to any one of claims 14 to 19, comprising at least one marker (17) extending on or embedded in the elongated tubular body, wherein the at least one marker (17) is visually perceptible or radiopaque.

21. A method according to any one of claims 14 to 20, characterized in that the elongated tubular body has a circumferential shoulder portion (18) that interconnects two axially adjacent regions of the elongated tubular body having different diameters.

22. A method according to any one of claims 14 to 21, characterized in that the elongated tubular body includes at least one lumen (19) extending within the wall of the elongated tubular body.

23. A method according to any one of claims 14 to 22, characterized in that the elongated tubular body has a wall thickness in the range of about 50 μm to about 500 μm.

24. A method according to any one of claims 14 to 23, characterized in that the cannula (4) is attached to the housing (1a) of the pump device (1) of an intravascular blood pump.

25. A method according to any one of claims 14 to 24, characterized in that the cannula (4) is provided for use as an intravascular blood pump for percutaneous insertion into a patient's blood vessel.

26. A method according to claim 3, characterized in that the spindle (7) is rotated at a speed of about 10 to 15 rpm.

27. A method according to claim 3, characterized in that the spindle (7) is rotated at a speed of about 12 rpm.

28. A method according to claim 1 or 5, characterized in that the base layer (10) has a thickness of about 50 μm to 100 μm when dry.

29. A method according to claim 6, characterized in that the first and second liquid materials are dispensed both before and after dispensing the fourth material so as to embed the stiffening structure (16) into the body of the cannula.

30. A method according to claim 7, characterized in that the proportion of the solvent is at least 80 vol%.

31. A method according to claim 7, characterized in that the proportion of the solvent is at least 90 vol%.

32. A method according to any one of claims 1 to 7, characterized in that at least one of the first and second axial regions (13, 15) is formed by dispensing at least 10, up to 20 layers of the first and second liquid material, respectively.

33. A method according to claim 9, characterized in that the two axially adjacent portions (7a, 7b) of the spindle (7) are separated from each other in order to remove the cannula (4) from the spindle (7).

34. A method according to claim 10, characterized in that the at least one label (17) is formed by dispensing a liquid material using the dispenser (8).

35. A method according to claim 19, characterized in that the helical wire is made of metal.

36. A method according to claim 19, characterized in that the helical wire is made of nitinol.

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