External drive unit for an implantable heart assist pump

Abstract

The present application relates to an external drive unit (7) for an implantable cardiac assist pump (4). The proposed drive unit (7) includes a motor (35) for driving the cardiac assist pump (4), said motor (35) may be connected to the cardiac assist pump (4) via a drive shaft (3) passing through the skin. The drive unit (7) further includes a heat diffuser (19), said heat diffuser (19) may include a contact surface configured to contact the patient's skin, may be in direct contact with the patient's skin, and may be arranged to lie flat against the patient's skin. The contact surface may be heat-conductively connected to the motor (35) to transfer heat generated by the motor (35) to the patient's tissue (45).

Description

Technology Field

[0001] This application relates to the field of medical technology. This application relates to an external drive unit for an implantable cardiac assist pump, and a cardiac assist device comprising the drive unit and the implantable cardiac assist pump. Background Technology

[0002] Cardiac assist devices for assisting a patient's cardiac function are known by the prior art. Such devices may include an implantable blood pump, which may be inserted into the ventricle by means of minimal penetration. Additionally, an external (or extracorporeal) motor may be provided to drive the blood pump. The motor is connected to the blood pump through the skin by a flexible drive shaft that may be rotatably mounted inside a transcutaneous catheter. The implantable elements of the device may be inserted through a perforation formed in the patient's groin. Related devices are disclosed, for example, in US 8,489,190 B2.

[0003] Problems with such cardiac assist devices arise in relation to the heat dissipated by the external motor. In some cases, the motor may be positioned close to the patient's body during the operation of the blood pump, particularly adjacent to the patient's legs. If the heat generated by the motor is not effectively removed, the motor may overheat, which can cause motor malfunction. Furthermore, if the motor body, heated by overheating, comes into contact with the patient's skin, it can pose a threat to the patient's health, especially if the patient cannot sense the heat and therefore fails to respond appropriately, for example, due to anesthetics. The amount of heat that human skin can safely absorb has been studied in the context of ultrasound and magnetic resonance imaging probes. For example, "Human Skin Temperature Response to Absorbed Thermal Power" (SPIE Proceedings - The International Society for Optical Engineering 3037:129-134, March 1997) discloses a method for determining a safe level of heat absorption.

[0004] To prevent the motor of a cardiac assist device from overheating, the body of such a motor may be equipped with multiple cooling fins to effectively dissipate heat from the motor and disperse it into the surrounding air. However, when the motor is operated in a sealed environment, such as when it is placed under bedding while the patient is resting or under surgical fabric used during surgery, the amount of heat transferable to the air may not be sufficient. Additionally, it is not easy to clean the surface of the body equipped with cooling fins.

[0005] US 20169 / 0213827 A1 discloses a catheter pump comprising a stator assembly and a motor assembly including a heat exchanger located around the stator assembly. The heat exchanger is configured to direct heat radially outward from the stator assembly and may include a tubular body having a lumen. Fluid flows through the lumen to transfer heat from the patient to the outside. The gap between the stator assembly and the external motor body acts as a natural insulator to prevent heat from the stator assembly from being transferred to the outside of the body surface. The problem to be solved

[0006] In light of the aforementioned current state of technology, the present application aims to provide an improved external drive unit for an implantable cardiac assist pump and an improved cardiac assist device.

[0007] Furthermore, the present application relates to an improved method for operating a cardiac assist device. In particular, the present application aims to enable the safe and efficient operation of a cardiac assist device. means of solving the problem

[0008] These objectives are achieved by an external drive unit having an embodiment of independent claim 1 and the method associated therewith. Optional additional embodiments and additional forms of application will become apparent from the dependent claims and the detailed description corresponding to the accompanying drawings.

[0009] The proposed external (external) drive unit for an implantable cardiac assist pump comprises a motor that drives the cardiac assist pump, said motor being connected to or capable of being connected to the cardiac assist pump via a drive shaft passing through the skin. Additionally, the drive unit includes a contact surface configured to contact the patient's skin, and a heat spreader arranged to be in direct contact with the patient's skin or to lie flat against the patient's skin. The contact surface is configured to be connected to or capable of being connected to the motor to enable heat transfer, thereby transferring heat generated by the motor to the patient's tissue.

[0010] The claimed drive unit provides a solution contrary to the conventional belief in prior art that, as in US 2016 / 0213827 A1, the motor of a cardiac assist pump must be driven away from the patient in order to effectively remove heat from it. The process of effectively removing heat in the proposed drive unit is achieved by transferring heat to the patient's tissues. Therefore, during the operation of the cardiac assist pump, heat is transferred from the motor to the contact surface of the heat dissipator. The heat transfer by thermal contact between the motor and the contact surface is sufficiently large to allow heat to be transferred to the patient's tissues via the heat dissipator generated by the motor.

[0011] The contact surface may be flat or curved. In typical embodiments, the contact surface is stepless. In preferred embodiments, the contact surface is flexible to ensure maximum contact with tissue. The entire contact surface may come into contact with the skin during use of the actuation unit. The actuation unit may be configured to include a bottom surface comprising the entire area of ​​the actuation unit shaped to come into contact with the patient's skin. The contact surface typically forms a part of the bottom surface. However, in some embodiments, the contact surface constitutes the entire bottom surface.

[0012] Additionally, the present application relates to a cardiac assist device comprising the drive unit described above or below, and further comprising an implantable cardiac assist pump. The cardiac assist device may further comprise a drive shaft passing through the skin. The cardiac assist pump may be connected to the drive unit in a manner inseparably connected, for example, through the drive shaft. In another embodiment, the drive unit may be connected to the drive shaft through a coupling, for example, a magnetic clutch.

[0013] Furthermore, the present application relates to a method of driving a cardiac assist device. In the method, a driving unit drives a cardiac assist pump, and heat generated by a motor is transferred to the patient's tissues by configuring the contact surface of a heat dissipator to be in contact with the patient's skin (or) or to be in direct contact with the patient's skin (or) or to be laid flat against the patient's skin. In most embodiments, the contact surface of the heat dissipator is in direct contact with the patient's skin. However, in some cases, another material, for example, a piece of the patient's clothing, may be interposed between the skin and the contact surface.

[0014] The motor typically comprises a body, and a heat dissipator may be attached to the motor body. In a typical embodiment, the motor body is an external body that is at least partially visible when the drive unit is assembled. The heat dissipator is provided on the outside of the motor body. The heat dissipator is configured to transfer heat from the motor to the patient's tissues. In most embodiments, the heat dissipator is a passive component that does not require a supply of electrical energy. Additionally, in most embodiments, the heat dissipator is not dependent on moving parts and / or moving fluids. The heat dissipator may be connected to the motor body in a fixed or movable manner. In some embodiments, the heat dissipator is connected to the body in a removable manner. For example, it may be convenient for a cardiac assist pump to be implanted in a catheterization lab without being connected to a heat dissipator. In such a situation, the motor body can serve as a handle for the cardiac assist device. After the implantation procedure, the motor body may be connected to the heat dissipator, thereby allowing the heat generated by the motor to be efficiently transferred to the patient's tissues.

[0015] The drive unit may include holding means configured to attach it to the patient's thigh. When the cardiac assist device is used, in a typical application scenario, at least the bottom surface of the drive unit comes into contact with the patient's skin. The contact surface may come into contact with the skin. Then, the proposed drive unit functions to effectively remove heat from the motor during the motor's operation. In this way, overheating of the motor can be prevented.

[0016] In a typical embodiment, cooling fins are not required. Therefore, the proposed drive unit can be designed to be relatively compact, thereby improving the ease of attachment and comfort of wearing. Furthermore, the amount of heat removed from the motor is predictable and does not strongly depend on the ambient temperature or airflow rate. Therefore, the heat management of the drive unit can be reliably controlled. Additionally, since cooling fins are not required, the main body can have a surface that is partially or entirely continuous and / or without steps. Therefore, cleaning of the drive unit can be facilitated.

[0017] Therefore, the drive unit can be advantageously used in different application scenarios.

[0018] First, during the process of implanting a cardiac assist device in a catheterization room, the motor may be placed on a sterile cloth, as the area beneath the cloth may be considered non-sterile. In such a situation, air convection around the motor is possible, thereby reducing the risk of overheating. Furthermore, the probability of the patient unintentionally coming into contact with the motor is low, and even if the user (surgeon) comes into contact with the motor, they are usually wearing gloves. Therefore, the permissible temperature of the motor is higher than in the second application scenario described below. In addition, the risk of contamination of the drive unit is relatively high because the user comes into contact with the motor while wearing contaminated gloves, particularly those heavily soiled with blood.

[0019] Second, it is important that the pump remains in place within the patient's body, especially during patient transport or while the patient is in an intensive care unit. In such situations, the motor must be firmly secured to the puncture site due to its weight. For this reason, the motor is placed under a blanket or quilt. Consequently, heat transfer by convection from the motor is inefficient, and the risk of the motor overheating during operation must be considered. Furthermore, in such scenarios, the pump is prone to direct contact with the patient. Therefore, it is desirable to ensure efficient heat transfer from the motor to the patient's tissues through the proposed drive unit. Additionally, cleaning may be required after prolonged use of the motor, and the surface geometry of the proposed drive unit is more advantageous compared to the designs of conventional known heat sinks that include cooling fins.

[0020] The surface area of ​​the contact surface of the heat spreader may be larger than the surface area of ​​the motor housing surface. The surface of the housing may be the surface of the housing that comes into contact with the patient. The heat spreader may have a size sufficient to extend far from the motor housing. In some embodiments, the surface area of ​​the contact surface is at least 25 cm² 2 , preferably at least 50cm 2 or at least 100cm 2 It is. Typically, the surface area is 400 cm² 2 It is smaller than. A sufficiently large surface area is essential because it enables efficient heat transfer from the motor to the patient's tissue. Furthermore, it is important to have a sufficiently large surface area to prevent localized overheating of the tissue and subsequent tissue damage. The amount of heat transferred to the patient's tissue is cm² 2 Up to 80mW per unit, preferably cm 2 Up to 60mW or cm per unit2 The maximum power per unit is 40mW, based on the surface area of ​​the contact surface. Additionally, when designing the thermal management of the drive unit, the surface area constitutes an important factor and ensures that the motor operates at a desirable temperature. In most embodiments, during the operation of the drive unit, the ratio of the surface area of ​​the contact surface to the heat emitted by the motor is at least 13cm² 2 / W, preferably 25cm 2 / W, more preferably 50cm 2 / W, and thereby prevents localized overheating of the tissue.

[0021] It is preferable that the heat diffuser be flexible, at least locally. This allows the contact surface to conform to the contours of the skin. For example, if the drive unit is attached to a patient's thigh, the contact surface can conform to the shape of the thigh. This allows the drive unit to be worn more comfortably and ensures thermal contact between the heat diffuser and the patient's skin. The heat diffuser may have flexibility over its entire surface.

[0022] The heat transferred to the tissue is generally not used for therapeutic purposes. In order to effectively transfer heat from the motor to the patient's tissue, it is desirable that the heat exchanger be composed of a material having relatively high thermal conductivity, at least partially. This area can be sufficiently extended across the entire contact surface. The thermal conductivity in the said area may be at least 1 W / (m·K), preferably at least 10 W / (m·K), at least 50 W / (m·K), or at least 100 W / (m·K). In a preferred embodiment, the thermal conductivity of the heat disperser is higher in the direction parallel to the contact surface of the heat disperser than in the direction perpendicular to the contact surface of the heat disperser, so that thermal energy is widely dispersed across the surface and to prevent the formation of hot spots.

[0023] To safely and effectively transfer heat from the motor to the patient's tissue, the heat distribution across the surface area is of the utmost importance; therefore, the heat diffuser is designed to have a flat shape, which can reduce the weight of the unit and the amount of material required. Thus, the heat diffuser can be configured to have a thickness of less than 2 cm, specifically less than 1 cm or 0.5 cm. For example, the heat diffuser can be a foil.

[0024] The heat disperser may include a heat-conducting layer. The heat-conducting layer enables heat to be transferred quickly and effectively over the entire surface area of ​​the contact surface, thereby preventing overheating of the skin. The heat disperser may further include a carrier layer. The carrier layer may have a lower thermal conductivity than the heat-conducting layer. The carrier layer may contain an elastomer and / or plastic. In this way, the heat-conducting layer, particularly a relatively thin and / or flexible layer, can conduct heat sufficiently, and the carrier layer ensures that the heat disperser has sufficient mechanical stability. The heat-conducting layer may contain a metal, particularly copper, aluminum, and / or pyrolytic carbon. In some embodiments, the heat disperser may be configured to include at least one heat-conducting layer.

[0025] In addition, the heat disperser may include a biocompatible coating layer. For example, the contact surface of the heat disperser may include a biocompatible coating layer. The coating layer may be formed on a portion of the bottom surface of the heat disperser or on the entire surface. The coating layer may cover or surround a heat conductive layer. In particular, if the heat disperser or its heat conductive layer contains harmful components that may be dissolved by sweat, the coating layer may be introduced in such cases. This allows the coating layer to prevent harmful components from reaching the patient's skin. For example, the biocompatible coating layer may include biocompatible materials such as parylene, polyurethane, silicone, PEEK, or, for example, implantable metal. The biocompatible coating layer may have a thickness of less than 2 mm, preferably less than 0.5 mm or less than 0.1 mm. The biocompatible coating material may be the same as the carrier material that implements the biocompatible carrier.

[0026] Additionally, the motor and / or motor body may have an elongated shape. When the drive unit is attached to the patient's thigh, the motor may be formed elongated so that the longitudinal direction of the motor and / or motor body aligns with the axial direction of the thigh. A fixing means is typically connected to the motor body. The fixing means of the drive unit may include strap and / or hook-and-loop fastening means. The fixing means may further include an adhesive. When the drive unit is attached to the thigh with an adhesive, the drive unit is fixed particularly reliably to the puncture site. In particular, when the drive unit is attached to the patient's thigh, fixing it with an adhesive serves as an effective fixing means to prevent the drive unit from sliding down from the thigh toward the tapered portion toward the knee. For example, mechanical stress acting on the puncture site can be reduced by the proposed fixing means. In some embodiments, the heat dissipator includes an adhesive surface that allows it to be attached to the skin. For example, the heat dissipator may be formed by an adhesive patch. According to such embodiments, heat generated by a motor can be transferred to the patient's tissue through the patch. The thermal conductivity of the patch is sufficiently high so that heat is effectively transferred to the tissue. The adhesive surface may be formed on part and / or the entire contact surface. The adhesive may be a biocompatible adhesive, for example, widely known from wound closure adhesive patches.

[0027] Additionally, the driving unit may further include a fixing means to prevent it from being repositioned elsewhere on the patient's skin. For example, the fixing means may include a region made of rubber. The bottom surface of the driving unit may further include a nub.

[0028] The heat dissipator may include openings or recesses, particularly through holes or grooves, thereby allowing sweat to evaporate from the skin. The openings or recesses may be located at least partially adjacent to the contact surface. In a typical embodiment, the heat dissipator includes at least three, at least five, or at least eight openings or recesses. Heat transferred to the patient's tissues during the motor's operation promotes perspiration. Therefore, the openings or recesses can significantly improve the comfort of wearing the drive unit. The smallest or uniform diameter of the openings or recesses to allow sufficient vapor transfer to the atmosphere is typically at least 1 mm or at least 5 mm. The largest or uniform diameter of the openings or recesses is typically up to 20 mm or 80 mm.

[0029] In some embodiments, the openings form a slender shape. The ratio of the largest diameter to the smallest diameter may be at least 1.2 or at least 2. In this way, sweat (in the form of vapor) can be efficiently transferred from the body to the atmosphere. At this time, sufficient mechanical stability and efficient two-dimensional heat conduction are ensured in the heat diffuser. For example, the openings may be formed slender, so that when the drive unit is attached to the patient's thigh, the openings have a larger diameter in the circumferential direction of the thigh and a smaller diameter in the axial direction of the thigh. When the motor has a slender shape in the axial direction, the slender holes allow heat to be effectively transferred in the circumferential direction while vapor is effectively removed from the skin.

[0030] In some embodiments, the heat disperser includes pores to function to transfer evaporated sweat from the skin to the atmosphere. The heat disperser includes a membrane having pores. The pores may have a size of at least 0.02 µm and / or up to 0.3 µm.

[0031] The heat diffuser may include a sweat-absorbing material, which may be fabric or cotton. The sweat-absorbing material may be formed on a portion of the bottom surface of the heat diffuser. The sweat-absorbing material absorbs sweat from the patient's skin and thus improves the wearability of the drive unit.

[0032] In some embodiments, the heat diffuser includes a heat pipe. The heat pipe may be flat. For example, the heat pipe may be a heat diffusor. Typically, the bottom surface of the heat pipe comes into contact with the patient's skin. In other embodiments, the heat pipe may be positioned between a motor and a heat diffusor and connected to them. The top surface of the heat pipe may be in thermal contact with the motor. The heat pipe may be capable of effectively transferring heat from the motor to the tissue or contact surface.

[0033] The motor may include a stator and a rotor. The rotor typically includes a magnet, in particular a permanent magnet. The stator may include multiple windings. The stator usually surrounds the rotor, thereby creating a magnetic gap between the rotor's magnet and the stator's windings. The rotor may be rotatably mounted. The motor may be connectable to or connected to a drive shaft. In some embodiments, a fluid gap is formed between the rotor and the stator. The fluid gap may be connected in the fluid to a purge opening for injecting a purge medium into the fluid gap. The purge medium may be a solution, namely a glucose solution or a saline solution. Typically, the cardiac assist device includes a catheter surrounding the drive shaft. The purging medium can be injected into the fluid gap and the lumen of the catheter, for example, the space between the catheter and the drive shaft. Therefore, the motor may be a purged motor. The cardiac assist device and / or drive unit may include a fluid transfer port, i.e., a pump, and the pump is arranged to allow the purging medium to flow in the distal direction of the fluid gap.

[0034] When a non-purged motor is used, a sealant may be required to isolate the motor from the space. This space is the area between the catheter and the drive shaft, and the sealant is intended to prevent air from entering this space and, ultimately, the patient. A purged motor may not require a complex sealant to isolate the motor from the space between the catheter and the drive shaft, and thus has an advantage in this regard. Therefore, the motor may be easier to manufacture, and friction losses may be reduced, allowing the motor to be driven more efficiently. However, compared to a non-purged motor, the efficiency of a purged motor may be reduced due to friction losses within the purging medium. Surprisingly, the disadvantageous low efficiency of the motor can be avoided by one of the embodiments described below and combinations thereof.

[0035] The width of the fluid gap can be at least 0.1 mm, preferably 0.2 mm. At the same time / or, the width of the fluid gap can be up to 1 mm, preferably 0.5 mm or 0.3 mm. It should be considered that the minimum size of the magnetic gap is limited by the size of the fluid gap. Typically, the rotor and / or stator includes a sleeve or coating layer that can define the range of the fluid gap. The surfaces defining the range of the fluid gap can be flat and / or stepless, preventing undercutting of the surface that reliably ensures the air circulation process. This allows the rotor magnets and / or stator windings to avoid the effects of corrosion from the purge medium. Consequently, the magnetic gap is usually larger than the fluid gap. Although magnetic losses are expected to increase as the width of the fluid (and magnetic) gap increases, it has been discovered that the overall efficiency of the motor improves when the width of the fluid gap is relatively large. Such improvements are related to a reduction in frictional losses in the purging medium.

[0036] As described above, the proposed drive unit enables precise control of motor thermal management in various application scenarios. In particular, it is possible to precisely control the temperature of the purge medium in the fluid gap. According to a typical embodiment, the temperature of the purge medium in the fluid gap is at least 50°C, preferably 60°C, under normal operating conditions. Additionally, the temperature of the purge medium in the fluid gap is up to 100°C, preferably up to 90°C, under normal operating conditions. By controlling the temperature of the purge medium, the temperature of the purge medium can be maintained at a level safe for the patient, and thus the viscosity of the purge medium can be reduced within a non-boiling range. Therefore, by controlling the temperature of the purge medium to lower friction losses in the fluid, the motor can be operated particularly efficiently.

[0037] To precisely control the temperature of the purge fluid, heat transfer between the fluid gap and the patient's skin must be analyzed and designed. For example, heat transfer from the fluid gap to the heat dissipator may be influenced by the material of the motor body. The body may be manufactured from or contain plastic materials, namely PEEK or ABS. Plastic materials are particularly suitable for enabling the motor to operate within a desired temperature range. In some embodiments, the motor body is shaped so that it can be used as a handle for the drive unit.

[0038] According to aspects described below, the driving unit may not include a heat dissipator as described above or below, or the driving unit may include a heat dissipator that prevents contact with the patient's skin. A method for removing heat from the motor can be implemented, for example, by a heat dissipator as described above or below, cooling fins attached to the motor body, or a heat pipe connected to the motor for the purpose of heat conduction. Additional embodiments become apparent by combining these aspects or from aspects described above or below.

[0039] In particular, the present application is related to the following aspects, among others.

[0040] 1. A method of driving a cardiac assist device comprising an external drive unit and an implantable cardiac assist pump, wherein the drive unit comprises a motor for driving the cardiac assist pump, the motor is connected to the cardiac assist pump through a drive shaft passing through the skin, the motor comprises a rotor rotatably mounted and connectable to a stator and a drive shaft, the fluid gap is formed between the rotor and the stator, the fluid gap is connected in the fluid to a purge opening for injecting a purge medium into the fluid gap, the cardiac assist device comprises a catheter surrounding the drive shaft, and the purge medium is injected into the fluid gap and the space between the catheter and the drive shaft.

[0041] 2. In the method of aspect 1, the temperature of the purging medium in the fluid gap is at least 50°C, preferably at least 60°C, under normal operating conditions.

[0042] 3. In any one of the aforementioned aspects, the temperature of the purging medium within the fluid gap is at most 100°C, preferably at most 90°C, under normal operating conditions.

[0043] 4. In any one of the aforementioned aspects, the purging medium is a glucose solution or saline solution.

[0044] 5. An external drive unit for an implantable cardiac assist pump includes a motor for driving the cardiac assist pump, said motor is connected to or can be connected to the cardiac assist pump through a drive shaft passing through the skin, and said drive unit includes a heat pipe connected to the motor in a heat-conducting manner.

[0045] 6. In the driving unit of aspect 5, the driving unit includes a motor body and a heat pipe connected to the body in a manner that allows for thermal conduction.

[0046] 7. A heart assist system comprising a drive unit of either aspect 5 or 6, and further comprising a console or controller unit having a heat sink, wherein a portion of the heat pipe is connected to the heat sink in a heat-conducting manner to remove heat from the motor. Effects of the invention

[0047] As described above, the proposed drive unit enables precise control of motor thermal management in various application scenarios. In particular, it is possible to precisely control the temperature of the purge medium in the fluid gap. Brief explanation of the drawing

[0048] FIG. 1 is a schematic diagram of a cardiac assist device comprising an implantable cardiac assist pump and an external drive unit. FIG. 2 is a schematic diagram of the above-mentioned driving unit, FIG. 3 is another schematic diagram of the above-mentioned driving unit, FIG. 4 is another schematic diagram of the above-mentioned driving unit, FIG. 5 is a schematic diagram showing a cross-section of a heat disperser and a motor body, FIG. 6 is a schematic diagram showing a cross- section of the heat disperser, and Figure 7 is a schematic diagram showing the motor body and a cross-section of the motor. Specific details for implementing the invention

[0049] Preferred embodiments are described together with the embodiments described below.

[0050] A schematic diagram of a cardiac assist device (1) is shown in FIG. 1. The cardiac assist device (1) includes a catheter (2). A flexible drive shaft (3) is guided within the catheter (2). The distal end (13) of the catheter (2) and the drive shaft (3) is connected to the pump head of a cardiac assist pump (4). The cardiac assist pump (4) includes a main body (5) and a propeller (6). The propeller (6) is connected to the distal end (13) of the drive shaft (3). The proximal end (14) of the drive shaft (3) is connected to an external drive unit (7) equipped with a motor (35). The drive unit (7) is configured to drive the rotational movement of the propeller (6) to move the patient's blood.

[0051] As well as the catheter (2) and the drive shaft (3), the cardiac assist pump (4) is inserted into the patient's femoral artery via a perforation (8) located in the patient's groin. As illustrated, the use of a cardiac assist device (1) to assist the function of the left ventricle (10) of the heart is depicted, and the cardiac assist pump (4) is partially located in the area of ​​the aortic valve (11) of the patient's left ventricle (10). When the cardiac assist device (1) is driven, the drive shaft (3) is driven by the motor (35) of the drive unit (7), and the cardiac assist device (1) transports blood from the left ventricle (10) to the aorta (12). That is, it transports blood from the terminal end (13) of the cardiac assist device (1) toward the terminal end (14). In other embodiments, the cardiac assist device (1) may be configured to transport blood from the base portion (14) of the cardiac assist device (1) toward the distal portion (13). When configured in this way, it is particularly suitable for assisting the function of the right ventricle of the heart.

[0052] As illustrated in FIG. 2, the drive unit (7) can be attached to the patient's thigh (15). The embodiment according to FIG. 2 and the embodiments described below use the same reference numerals. In the illustrated embodiment, the drive unit (7) is positioned and fixed in the perforation (8) by a band (16), i.e., an elastic band. In most embodiments, the length of the band (16) is between 45 and 60 cm. However, other fixing means are possible as described below. The motor (35) is placed within the motor body (17), i.e., an ABS part formed by an injection method. In most embodiments, the surface of the motor body (17) is flat and without steps so that the body (17) is easy to clean and can function as a handle for the cardiac assist device (1). The catheter (2) is firmly connected to the base (14) of the motor body (17) in a fluid-tight manner. Additionally, a supply line (18) is schematically illustrated in the drawing. The supply line (18) is connected to the base portion (14) of the motor body (17) and includes a supply line (18) for supplying power to the motor (35) and a fluid supply line (18) for a purging medium. In other embodiments, the fluid supply line and the power supply line are each guided into the interior of one of a plurality of separate supply lines (18).

[0053] The driving unit (7) further includes a heat diffuser (19). The heat diffuser (19) is firmly connected to the motor body (17) so that heat generated from the motor (35) during operation is transferred to the heat diffuser (19). The heat diffuser (19) may be thin and may have a thickness of 4 mm or less. For example, the heat diffuser (19) may be formed as a patch or as a flat two-dimensional heat pipe as described below. The bottom surface of the heat diffuser (19) is mounted flat while in direct contact with the patient's skin. Thus, heat can be transferred from the heat diffuser (19) to the patient's tissue (45). During the driving process of the motor (35), the outer surface temperature of the body (17) will exceed 43°C before the heat diffuser (19) is fixed to the thigh (15). However, the thermal conductivity of the heat disperser (19) must be ensured so that heat is evenly distributed over a sufficient area of ​​the heat disperser (19) and transferred to the thigh (15), thereby allowing the temperature on the surface of the main body (17) to decrease rapidly to 42°C or lower, which is defined as the critical temperature at which the tissue (45) can be damaged.

[0054] The heat disperser (19) includes a region having a thermal conductivity greater than 100 W / (m·K) so that heat is dispersed to the left and right. This allows heat to be efficiently transferred across the entire contact surface. The surface area of ​​the contact surface is 200 cm² in some embodiments. 2 It can be as large as that. The heat diffuser (19) further includes openings (through holes), two of which are labeled 20 and 20'. The openings function to allow evaporated sweat to be transferred into the atmosphere (46), thereby enhancing comfort of wearing.

[0055] A perspective view of the drive unit (7) is shown in FIG. 3. In the illustrated embodiment, the heat diffuser (19) has a recess (22) for receiving the body (17) of the motor (35). The band (16) includes a hook and loop fastening mechanism, said mechanism having a looped surface (23) for securing a corresponding hooked surface located at the end of the band (16), which is not illustrated. When the heart assist device (1) is used, the motor body (17) is received in the recess (22), and the band (16) wraps around the thigh (15) in the circumferential direction (24), thereby covering the motor body (17) with a part of the band (16) and fixing the drive unit (7) in place.

[0056] The opening of the heat disperser (19) can be shaped to be long and narrow as shown in FIG. 4. In this case, the opening has a larger diameter in the circumferential direction (24) relative to the thigh (15), thereby allowing heat to be efficiently transported in the circumferential direction (24) by the heat disperser (19). The motor body (17) is formed to be long in the vertical direction (25) so as to correspond to the axial direction of the thigh (15).

[0057] The heat diffuser (19) may be implemented in a curved or flexible manner to correspond to the shape of the thigh (15). For example, the heat diffuser (19) may include a foil or a patch. FIG. 5 shows an exemplary cross-sectional view of the heat diffuser (19) and the motor body (17) formed by the first patch (26) and the second patch (27). The patches (26, 27) are each bendable and include an adhesive layer (33) on the bottom surfaces (28, 29). In the illustrated embodiment, the patches (26, 27) surround the motor body (17) thereby efficiently drawing heat from the motor (35). In the illustrated embodiment, the adhesive surfaces of the heat diffuser (19) function as a fixing means for fixing the drive unit (7) in place with respect to the perforation (8). Therefore, other fastening means such as the aforementioned band (16) may be unnecessary, but in some embodiments, the band (16) may still be used.

[0058] FIG. 6 shows an exemplary cross-sectional view of a heat disperser (19). The heat disperser (19) may have a multi-layered structure. The heat disperser (19) includes a carrier layer that constitutes the top layer of the heat disperser (19). The carrier layer may be formed by an elastic material and / or a plastic material. To ensure efficient heat transfer across the contact surface area, i.e., in the horizontal direction in the drawing, it may be formed by a thin layer made of a material having high thermal conductivity, namely copper, aluminum, or pyrolytic carbon. One of the two sides of the heat conductive layer (31) may comprise a biocompatible material such as parylene, polyurethane, silicone, PEEK, or, for example, an implantable metal. A biocompatible coating layer (32) may cover the heat conductive layer (31) of the inner wall of the opening of the heat disperser (19). An adhesive layer (33), including, for example, glue, is formed on the flat bottom surface of the heat disperser (19) to fix the heat disperser (19) to the patient's skin.

[0059] Additionally, a schematic diagram of the sweat-absorbing portion (34) of the heat disperser (19) or the driving unit (7) is shown in FIG. 6. The sweat-absorbing portion (34) may be made of, for example, fabric and / or cotton. Additionally, the heat disperser (19) or the driving unit (7) includes a rubberized area (48) having rubber knots (49, 49') to prevent the heat disperser (19) from sliding against the perforation portion (8). The sweat-absorbing portion (34) and the rubberized area (48) may be evenly distributed across the bottom surface of the heat disperser (19).

[0060] FIG. 7 shows a schematic diagram of a motor (35). The motor (35) is placed inside a motor body (17) and includes a rotor (36) equipped with a permanent magnet and a stator (37) equipped with a winding (38). The rotor (36) is rotatably mounted through a first bearing (39) and a second bearing (40) and can rotate when current flows through the winding (38) of the stator (37). The rotor (36) is firmly connected to a drive shaft (3) to drive a propeller (6).

[0061] The catheter (2) is firmly connected to the motor body (17), and a space (41) is provided between the catheter (2) and the drive shaft (3). This space (41) is connected to a fluid gap (43) formed between the rotor (36) and the stator (37) in the fluid, and is equipped with a purge opening (42) and a supply line (18). The width of the fluid gap (43) in the radial direction can be between 0.2 mm and 0.3 mm. When the cardiac assist device (1) is driven, the purge medium, for example as a glucose solution, is supplied through the supply line (18) and flows through the fluid gap (43) and the space between the catheter (2) and the drive shaft (3) (and, eventually, flows from the base (14) of the cardiac assist device (1) to the patient).

[0062] During the operation of the motor (35), power consumption of, for example, 2W occurs, which may cause the motor (35) to heat up. As illustrated by the arrow of reference numeral 44, heat is removed from the motor (35). This is to maintain the temperature of the glucose solution inside the fluid gap (43) at a constant 75°C under normal operating conditions. To remove heat, as described above, heat may be transferred to the patient's tissue (45), for example, through a heat diffuser (19), or transferred to the atmosphere (46), for example, using cooling fins formed on the main body (17), or transferred to a heat sink (47) of a control panel or control unit, for example, through a long, thin heat pipe connected to the main body (17). A combination of these heat removal mechanisms is also possible.

[0063] Additionally, an inductor (50) may be provided to reduce eddy-current losses that occur when the motor (35) is not driven in a complete block commutation state. These inductors (50) may be located inside the motor body (17), but in a preferred embodiment, the inductor (50) is located at the end of the motor supply line (18) connected to the control unit of the motor (35) (or the control unit itself) to prevent additional weight or heat source from being added to the motor (35) and the patient's leg.

[0064] In particular, the present application may be more related to the aspects described below.

[0065] 1. The external drive unit (7) of the implantable heart assist pump is,

[0066] It includes a motor (35) for driving a heart assist pump (4), said motor (35) is connectable to the heart assist pump (4) through a drive shaft passing through the skin, and

[0067] The heat diffuser (19) is characterized by including a contact surface configured to come into contact with the patient's skin, wherein the contact surface is connected to or can be connected to the motor (35) to enable heat transfer in order to transfer heat generated from the motor (35) to the patient's tissue (45).

[0068] 2. The driving unit (7) of aspect 1 has a contact surface area of ​​at least 25 cm 2 , preferably at least 50cm 2 It is characterized by being.

[0069] 3. The driving unit (7) of either aspect 1 or 2 is characterized in that the heat disperser (19) is at least partially flexible.

[0070] 4. Any one of the driving units (7) of aspects 1 to 3 is characterized in that the heat disperser (19) is a foil or a patch.

[0071] 5. Any one of aspects 1 to 4, the driving unit (7) is characterized in that the heat disperser (19) includes a heat conductive layer (31), and the heat conductive layer (31) contains a metal, particularly copper, aluminum and / or pyrolytic carbon.

[0072] 6. Any one of aspects 1 to 5, the driving unit (7) is characterized in that the heat disperser (19) includes a biocompatible coating layer (32).

[0073] 7. Any one of aspects 1 to 6, the driving unit (7) is characterized by the heat disperser (19) including an adhesive surface for attaching it to the skin.

[0074] 8. Any one of aspects 1 to 7, the driving unit (7) is characterized by including an opening (40, 40') or a recess (22) that allows the heat diffuser (19) to allow sweat to evaporate from the skin.

[0075] 9. The driving unit (7) of aspect 8 is characterized by having an opening (40, 40') formed to be thin and long.

[0076] 10. Any one of aspects 1 to 9, the driving unit (7) is characterized in that the heat disperser (19) includes a sweat-absorbing material, particularly a fabric.

[0077] 11. Any one of aspects 1 to 10, the driving unit (7) is characterized by a motor (35) comprising a rotor (36) that is connectable to and rotatably mounted on a driving shaft (3), wherein a fluid gap (43) is formed between the rotor (36) and the stator (37), and the fluid gap (43) is connected in the fluid to a purge opening (42) for injecting a purge medium into the fluid gap (43).

[0078] 12. The driving unit (7) of aspect 11 is characterized by the fluid gap (43) having a maximum width of 1 mm.

[0079] 13. The driving unit (7) of aspect 11 or 12 is characterized by having a fluid gap (43) with a width of at least 0.1 mm.

[0080] 14. Any one of the driving units (7) of aspects 1 to 13 is characterized in that the heat disperser (19) includes a heat pipe.

[0081] 15. A cardiac assist device (1) comprising a driving unit of any one of the aforementioned aspects and an implantable cardiac assist pump (4).

[0082] 16. As a method of driving the heart assist device (1) of aspect 15, the heart assist pump (4) is connected to a driving unit (7) through a driving shaft (3), the driving unit (7) drives the heart assist pump (4), and the contact surface of the heat disperser (19) is in contact with the patient's skin so that heat generated by the motor (35) is transferred to the patient's tissue (45).

[0083] 17. As a method of modality 16, the amount of heat delivered to the patient is a maximum of 80 mW / cm² relative to the surface area of ​​the contact surface. 2 am.

[0084] 18. In the method of aspect 16 or 17, the driving unit (7) is the driving unit (7) according to aspect 11, and the cardiac assist device (1) includes a catheter (2) surrounding the driving shaft (3), and the purging medium is injected into the fluid gap (43) and into the lumen of the catheter (2) or the space between the catheter (2) and the driving shaft (3).

[0085] 19. As a method of aspect 18, the temperature of the purging medium in the fluid gap (43) under normal operating conditions is at least 50°C, preferably at least 60°C.

[0086] 20. In the method of aspect 18 or 19, the temperature of the purging medium in the fluid gap (43) under normal operating conditions is at most 100°C, and preferably at most 90°C.

Claims

Claim 1 An external drive unit for an implantable cardiac assist pump comprising a motor for driving a cardiac assist pump, wherein the motor is connectable to or connected to the cardiac assist pump through a drive shaft passing through the skin, and the drive unit comprises a heat pipe connected to the motor in a heat-conducting manner. Claim 2 In claim 1, the driving unit includes a motor housing, and the heat pipe is connected to the housing in a manner that allows for heat conduction. Claim 3 In paragraph 1 or 2, the heat pipe is a flat, driving unit. Claim 4 In paragraph 1 or 2, the heat pipe is a heat diffusing material, and the driving unit. Claim 5 A driving unit configured such that the bottom surface of the heat pipe contacts the patient's skin, in accordance with claim 1 or 2. Claim 6 A drive unit according to claim 1 or 2, wherein the upper surface of the heat pipe is in thermal contact with the motor. Claim 7 A driving unit according to claim 1 or 2, comprising a heat disperser including a contact surface configured to contact the patient's skin, wherein the contact surface is heat-conductingly connected to or connectable to a motor to transfer heat generated by the motor to the patient's tissue. Claim 8 In paragraph 7, the heat pipe is positioned between the motor and the heat disperser and connected to the drive unit. Claim 9 A driving unit according to claim 1 or 2, comprising a fixing means configured to attach the driving unit to the patient's thigh. Claim 10 In paragraph 9, the fixing means is a drive unit connected to the housing of the motor. Claim 11 In claim 9, the fixing means is a drive unit comprising a strap. Claim 12 In claim 9, the fixing means comprises a driving unit including a hook and loop fastening means. Claim 13 In paragraph 9, the fixing means is a driving unit comprising an adhesive. Claim 14 A heart assist system comprising a drive unit of claim 1 or 2, and further comprising a console or control unit having a heat sink, wherein a portion of a heat pipe is heat-conductively connected to the heat sink to remove heat from the motor.

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