JP2006000631A - Internally implantable auxiliary artificial heart - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internally implantable auxiliary artificial heart device providing physiologic pulsatile flow and capable of being implanted in a diminutive body such as a Japanese. <P>SOLUTION: The internally implantable auxiliary artificial heart device providing the physiologic pulsatile flow employs an undulation pump and a developed technique for miniaturization and higher performance thereof. The device comprises the undulation pump 5, a drive shaft 6 with a swinging mechanism 14, and a motor 7. The undulation pump has a polyurethane housing 10 made by vacuum casting, a titanium disc 8, and a polyurethane membrane 9 for sealing the drive shaft 6. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

Detailed Description of the Invention

  The present invention relates to an implantable auxiliary artificial heart that is used by being attached to a failing heart in a state of being implanted in the body for assisting cardiac function of a patient with severe end-stage heart failure.

Prior art and its problems

  As a conventional implantable auxiliary artificial heart, an auxiliary artificial heart of a type that drives a sac type and a diaphragm type positive displacement pump by a mechanical method or an electromagnetic fluid method has been put into practical use. These assistive artificial hearts are very good in that they can achieve physiological pulsatile flow, but they are only developed in the United States and are large in size because they are intended for Westerners. There is a problem that adaptation is limited to people with a small physique. On the other hand, with the aim of miniaturization of implantable auxiliary artificial hearts, centrifugal pumps and axial flow pumps are in the clinical trial stage, but it is difficult to create pulsatile flow with these auxiliary artificial hearts. There is a problem that it can only be used as a non-physiological continuous flow auxiliary artificial heart.

Problems to be solved by the invention

  Therefore, there is a long-awaited realization of an implantable auxiliary artificial heart with a physiological pulsatile flow that can be embedded in a small physique such as the Japanese.

Means for solving the problem

  In order to realize this, the present invention uses a wave pump (general name of the pump described in Japanese Patent No. 3285386 previously invented by Yusuke Abe, one of the present inventors), which is reduced in size and highly durable. To develop a pulsatile and implantable assistive heart by developing a technology to improve the performance and performance.

  The basic configuration of the implantable auxiliary artificial heart includes a wave pump, a drive shaft, and a motor.

  A wave pump is a pump in which a disk with a notch on one side is installed in a chamber with a partition so as to engage with the notch, and an input / output port opens across the partition. This is a volume-moving continuous flow pump that converts fluid from an input port to an output port by converting it into a rocking motion of a disk.

  A feature of the wave pump is that a physiological pulsatile flow can be ejected by controlling the rotation of the motor. Utilizing this feature, the present invention uses a wave pump in a pulsatile flow mode.

  In order to reduce the size, durability, and performance of wave pumps, it was necessary to simultaneously improve the durability and manufacturing accuracy of the pump itself. In the past, polyurethane resin discs were used and the membrane was bonded, but this limited the durability and manufacturing accuracy of the membrane adhesion part, and the disc also deformed after resin molding. As a result, there was a problem that the yield was poor. As a method for improving this, a thermoplastic material or segmented polyurethane was used, and a disk was inserted and the film was integrated with the disk and injection molded successfully. As the thermoplastic material, it was found that thermoplastic elastomers are good, urethane type is particularly suitable, and ester elastomers, ether elastomers, and polycarbonate elastomers can be used. Other thermoplastic elastomers that can be used include vinyl chloride, styrene, oliffin, and fluorine. In addition, the drive shaft was completely sealed by a method in which the surface of the disk was covered with a film material continuously from the film. Furthermore, in order to reduce the size of the wave pump, it is necessary to increase the pump efficiency, but in polyurethane resin, the phenomenon that the pump efficiency decreases due to the bending and deformation of the disk due to the rocking motion of the disk may occur. It turns out that the rigidity of the disk is very important. As a method of dealing with this problem, the material of the disk is a composite material added with glass fiber, carbon fiber, calcium titanate, etc. PBT (polybutylene terephthalate), POM (polyoxymethylene), PP (polypropylene), It has been found that a rigid material such as TPU (thermoplastic polyurethane) or a metal such as titanium, stainless steel, iron or aluminum may be used.

  The drive shaft also needed to be small and highly durable. Conventionally, the drive shaft is configured by concentrically arranging the rotation prevention mechanism and the swing mechanism at the center of the wave pump. However, this increases the diameter of the drive shaft, so the space at the center of the wave pump is increased. And the performance of the pump is reduced. In order to improve the performance of the pump, it is necessary to reduce the space at the center of the wave pump. To achieve this, the diameter of the drive shaft must be reduced. Moreover, in the conventional drive shaft structure, since a ring is used for the rotation prevention mechanism, sufficient durability cannot be obtained for the drive shaft. As a method to improve the performance of the pump and the durability of the drive shaft at the same time, the rotation prevention mechanism and the swing mechanism are separated, and only the rotation prevention mechanism is installed at the center of the wave pump. Has devised a structure in which the drive shaft is configured in series with an anti-rotation mechanism.

  In order to realize an implantable auxiliary artificial heart, it is important to reduce the operating noise as well as to make the drive shaft smaller and more durable, and it is necessary to prevent the generation of noise from the body. Previously, a part of the bearing that supported the drive shaft was installed outside the drive shaft, and the bearing was fixed to the stator part of the motor. However, there is a difference in accuracy when the stator is fixed to the pump. An operating noise occurred. In order to prevent this, the operation noise due to the difference in accuracy has been greatly reduced by incorporating all the bearings in the drive shaft.

  In order to reduce the size of the auxiliary artificial heart, it was necessary to reduce the size of the motor. As a method for realizing this, a motor was constructed using a flat stator that was integrated with a swing mechanism and connected to a wave pump.

  Further, an important performance as an artificial heart is antithrombogenicity, and it is necessary to impart antithrombogenicity to the blood contact surface in the wave pump. As a method, all blood contact surfaces in the wave pump were coated with an antithrombotic material. As the antithrombogenic coating material, segmented polyurethane, MPC polymer, heparin coating, gelatin coating and the like can be used. Under short-term use conditions, either may be used, but it has been found that it is better to coat with segmented polyurethane or MPC polymer to obtain long-term antithrombogenic properties on the order of several months. The method of multilayer coating of segmented polyurethane and MPC polymer was also successful.

  Regarding the rotation prevention mechanism, conventionally, gear meshing and a universal joint using a ring and a bearing have been used. However, the operation noise is large in the gear, and there is a problem in durability in the ring and the bearing. Finally, these problems were solved by devising an anti-rotation mechanism composed of a cross-shaped shaft and bush.

  The balance of the drive shaft was also an important issue. Conventionally, the anti-rotation mechanism and the oscillating mechanism were concentrically arranged at the center of the wave pump to configure the drive shaft, so the dynamic balance was automatically taken, but the anti-rotation mechanism and the oscillating mechanism were separated, Due to the connection in series, the dynamic balance was not automatically achieved and vibration occurred. In order to prevent vibration, a weight was embedded inside the swing mechanism to achieve a dynamic balance.

  As the auxiliary artificial heart becomes smaller and more efficient, heat generation of the motor becomes a problem. Therefore, a heat sink is embedded in the housing of the wave pump, and the heat of the motor is induced to cool the blood.

  With the above configuration, the implantable auxiliary artificial heart has achieved significant size reduction, high durability, and high performance, and can be implanted into a person with a small physique such as the Japanese. I was able to realize the heart.

Embodiments of the Invention

  Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings.

  An implantable assistive heart system as shown in FIG. 1 is configured. This auxiliary artificial heart system assists the pumping function of the left ventricle. The implantable auxiliary artificial heart 1, the implantable control device 2 incorporating the battery and the transcutaneous information transmission system, and the transcutaneous energy transmission system. 3 and the extracorporeal system 4. The implantable auxiliary artificial heart 1 is connected to the left ventricle. When a system for assisting both the left heart and the right ventricle is configured, two implantable auxiliary artificial hearts 1, an implantable control device 2, a transcutaneous energy transmission system 3, and an extracorporeal system are used. 4 may be used. In this case, the two implantable auxiliary artificial hearts 1 are connected to the left ventricle and the right ventricle, respectively. The present invention relates to an implantable auxiliary artificial heart 1.

  Hereinafter, description will be made with reference to FIGS. 2, 3, and 4. The implantable auxiliary artificial heart 1 includes a wave pump 5, a drive shaft 6 and a motor 7.

  The disc 8 of the wave pump 5 was made of titanium. A polyurethane membrane 9 for sealing the drive shaft is integrally formed on the disk 8, and at the same time, the blood contact surface portion of the disk is coated with polyurethane of the same material with a thickness of about 0.5 mm. Polyurethane was injection-molded integrally by inserting a disc. As the material of the membrane, thermoplastic elastomer (trade name: Milactolan, Nippon Milactolan) or segmented polyurethane (trade name: Cardiomat or K-3, Nippon Zeon) was used.

  The housing 10 was made by vacuum casting using polyurethane. A heat sink 11 was embedded on one side of the housing facing the motor stator.

  The drive shaft sealing film 9 formed integrally with the disk 8 was fixed to the housing with a ring 12, and the same part was bonded using a solvent.

  The blood contact surface portion inside the pump was coated with segmented polyurethane (trade name: K-3) with a thickness of about 20 microns. When the segmented polyurethane was not coated, the MPC polymer was coated. Further, in the case of covering both in combination, after coating with segmented polyurethane, the MPC polymer was further coated.

  The drive shaft 6 includes a rotation prevention mechanism 13 and a swing mechanism 14. The anti-rotation mechanism 13 is positioned at the center of the disk 8 and uses a cross-shaped shaft 15 and a bush 16 at the center in the form of a universal joint, one orthogonal axis is the disk 8 and the other is the housing 10. Fixed to.

  In the swing part 14, the rotational motion of the motor 7 is converted into a swing motion using the bearing 17. Since the portion of the rotation preventing mechanism 13 fixed to the disk 8 is simultaneously connected to the swing mechanism 14, the motion of the swing mechanism 14 is converted into the swing motion of the disk 8. The swing mechanism 14 was fixed to be freely rotatable by a bearing 19 built in the base 18, and the base 18 was fixed to the housing 10. The swing mechanism 14 is embedded with a tungsten weight 20 for dynamic balance.

  The motor 7 is configured so as to partially cover the pedestal 18 and includes a mover 21 integrated with the swing mechanism 14 and a flat stator 22 connected to the wave pump 5. The mover 21 was manufactured by soft iron as a core and a plurality of neodymium iron magnets adhered, and the surface was coated with titanium nitride to prevent rust. The stator 22 was embedded with epoxy. In addition, a heat sink 23 and a temperature sensor 24 are incorporated in the stator 22. Since the heat sink 23 is in contact with the pedestal 18 and the pedestal 18 is in contact with the heat sink 11 of the housing 10, the heat generation of the stator 22 can be cooled with blood.

  With the above configuration, the size is 69 mm and the width is 35 mm, and the implantable auxiliary artificial heart has been significantly reduced in size. As shown in FIG. 5, a continuous flow output of about 13 liters per minute is obtained with a normal average blood pressure pressure load as shown in FIG. 5, and the pulsating flow has sufficient performance. With regard to antithrombogenicity, in animal experiments up to now, the electrical system troubles have not been completely solved, so the experimental animals have survived for about two months, but both anticoagulant therapy and antiplatelet have not been applied. Even did not see the formation of blood clots. Empirically, the segmented polyurethane alone should provide about 10 months, the MPC polymer alone about 7 months, and the MPC polymer and segmented polyurethane composite can provide yearly antithrombogenicity.

The invention's effect

  As described above, according to the present invention, an implantable auxiliary artificial heart with a physiological pulsatile flow of a size that can be embedded in a person with a small physique such as a Japanese can be realized. In spite of being able to do so, it is possible to save the lives of patients with end-stage severe heart failure who have died waiting for heart transplantation in Japan, where heart transplantation is not established due to a significant donor shortage.

Other

  The basic research on which the present invention was based was carried out by a research grant through the Basic Research Promotion Project in the Pharmaceuticals and Medical Devices Agency / Health and Medical Field.

  1 is a schematic diagram of an implantable assistive heart system. FIG.   It is an assembly schematic diagram of an implantable auxiliary artificial heart.   It is sectional drawing of an implantable auxiliary artificial heart.   It is the front and sectional drawing of a drive shaft.   It is a performance figure of an implantable auxiliary artificial heart.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Implantable auxiliary artificial heart 2 Implantable control apparatus 3 Transcutaneous energy transmission system 4 Extracorporeal system 5 Wave pump 6 Drive shaft 7 Motor 8 Disc 9 Membrane 10 Housing 11 Heat sink 12 Ring 13 Anti-rotation mechanism 14 Oscillation Mechanism 15 Cross-shaped shaft 16 Bush 17 Bearing 18 Base 19 Bearing 20 Weight 21 Movable element 22 Stator 23 Heat sink 24 Temperature sensor

Claims (15)

  A disc with a notch in one place is placed in a chamber that has a shape that surrounds the movement range when the disc is swung, and the chamber corresponds to the notch in the disc. A wave pump in which a pump chamber is formed by a pair of membranes, a disk and a chamber formed integrally with a disk, and a rotation installed at the center of the disk Implantable auxiliary artificial heart characterized by comprising a drive shaft constituted by a swing mechanism connected in series to the prevention mechanism and the rotation prevention mechanism, and a motor arranged in the swing mechanism portion of the drive shaft .   2. The implantable assistive heart according to claim 1, wherein a membrane material covers the surface of the disk continuously with the membrane.   The implantable auxiliary artificial heart according to claim 2, wherein a rigid material is used for the disc.   The implantable auxiliary artificial heart according to claim 2, wherein a metal is used for the disc.   2. The implantable auxiliary artificial heart according to claim 1, further comprising an anti-rotation mechanism including a cross-shaped shaft and a bush.   2. The implantable assistive heart according to claim 1, wherein the wave pump has a film made of a thermoplastic elastomer material.   2. The implantable auxiliary artificial heart according to claim 1, wherein the wave pump has a membrane made of segmented polyurethane.   2. The implantable auxiliary artificial heart according to claim 1, wherein the wave pump has a blood contact surface coated with an antithrombotic material.   The implantable artificial heart according to claim 8, wherein segmented polyurethane is used as the antithrombotic material.   9. The implantable assistive heart according to claim 8, wherein MPC polymer is used as an antithrombotic material.   2. The implantable auxiliary artificial heart according to claim 1, wherein the motor is composed of a mover integrated with the swing mechanism and a flat stator connected to the wave pump.   13. The implantable auxiliary artificial heart according to claim 12, which has a mover having soft iron as a core, a plurality of magnets adhered, and coated with titanium nitride.   2. The implantable auxiliary artificial heart according to claim 1, wherein a weight for dynamic balance is embedded in the swing mechanism.   2. The implantable auxiliary artificial heart according to claim 1, wherein a bearing is built in the drive shaft and no bearing is installed outside the drive shaft.   2. The implantable auxiliary artificial heart according to claim 1, wherein a heat sink is built in the housing of the wave pump.

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