Apparatus for cardiac assist

Abstract

A cardiac assist device is disclosed. A cardiac assist device according to an embodiment of the present invention comprises an electroactive polymer and a spring coupled to the lower side of the electroactive polymer, wherein when voltage is applied, the rigidity of the electroactive polymer weakens so that the compressed spring is restored and pushes the electroactive polymer to perform cardiac compression, and when voltage supply is interrupted, the rigidity of the electroactive polymer strengthens so that the spring is compressed and cardiac relaxation is performed, and an interface that transmits the force generated by the driving unit to the heart when voltage is applied to press the heart.

Description

Technology Field

[0001] The present invention relates to a cardiac assist device, and more specifically, to a cardiac assist device that assists in the reduction of cardiac contractile function by applying external pressure to the heart.

[0002] This invention was carried out with support from the Seoul National University Bio-Connect Support Project (research period 2022.05.10~2023.05.09) and the Seoul National University Creative Leading Young Researcher Support Project (Project No. 0420-20240115).

[0003] This invention was made under the supervision of Seoul National University Bundang Hospital with the support of the following in-hospital research project.

[0004] MSRI project number is 16-2022-0002, the research management agency is Seoul National University Bundang Hospital, the project name is “Right ventricular assist device using electroactive polymer”, the lead institution is Seoul National University Bundang Hospital, and the research period is 2022-05-10~2024-12-31. Background Technology

[0005] Heart failure (HF) is a condition in which the heart is unable to supply sufficient blood to the body due to a decline in its systolic function. Patients with heart failure continuously experience chronic symptoms such as shortness of breath, fatigue, exercise intolerance, and edema. Therefore, there is a need to support the reduced systolic function by directly circulating blood or applying external pressure to the heart.

[0006] In the past, mechanical circulatory assist devices (MCS), such as left ventricular assist devices (LVADs) and total artificial hearts (TAHs), have been developed.

[0007] Since these mechanical circulation aids use a method of circulating blood by driving a rotor with a motor, direct contact occurs between the rotor and the blood. Consequently, there was a risk of serious side effects such as the formation of blood clots, stroke, or infection.

[0008] In addition, the need for high power consumption and the necessity of heavy battery packs and thick power supply cables increased the risk of infection and became a factor that made clinical application more difficult. Prior art literature

[0009] Korean Registered Patent No. 1679221 (Title of Invention: Cardiac pacemaker using electroactive polymer and cardiac pacemaker using the same, Registration Date: November 18, 2016) The problem to be solved

[0010] The objective of the present invention is to solve these conventional problems by providing a cardiac assist device that can efficiently assist the heart with low power consumption while minimizing contact with blood, by allowing the stiffness of the electroactive polymer to weaken when voltage is applied, thereby restoring the compressed spring to push the electroactive polymer out to perform cardiac compression, and allowing the stiffness of the electroactive polymer to strengthen when voltage is stopped, thereby compressing the spring to perform cardiac relaxation.

[0011] The problems of the present invention are not limited to those mentioned above, and other problems not mentioned will be clearly understood by a person skilled in the art from the description below. means of solving the problem

[0012] To solve the above-mentioned problem, a cardiac assist device according to one aspect of the present invention comprises an electroactive polymer and a spring coupled to the lower side of the electroactive polymer, wherein when voltage is applied, the rigidity of the electroactive polymer weakens so that the compressed spring is restored and pushes the electroactive polymer to perform cardiac compression, and when voltage supply is interrupted, the rigidity of the electroactive polymer strengthens so that the spring is compressed and cardiac relaxation is performed, and an interface that transmits the force generated by the driving unit to the heart when voltage is applied to press the heart.

[0013] The electroactive polymer can be provided with a structure in which a flexible electrode is coated on a dielectric elastomer so that the rigidity weakens when voltage is applied and strengthens when voltage supply is stopped.

[0014] It may further include an electrical connection line connecting the electroactive polymer and the voltage source.

[0015] The spring may include a negative bias spring.

[0016] The spring is provided with a curved shape symmetrical with respect to the center, so that symmetrical deformation can occur simultaneously when voltage is applied or voltage supply is interrupted.

[0017] The spring, the electroactive polymer, and the center of the interface are connected to each other and may further include a central axis that transmits the force generated by the driving unit to the heart in a vertical direction.

[0018] The electroactive polymer is provided with an inner holder in a through hole formed in the center, and the central axis is coupled to the spring center and the inner holder to connect the spring and the electroactive polymer.

[0019] It may further include a housing in which a spring is placed, and an outer holder coupled to the upper part of the housing and supporting the outer circumference of an electroactive polymer.

[0020] It may further include a sleeve that wraps around the outer surface of the housing and surrounds the heart, allowing the interface to remain in contact with the heart.

[0021] The interface can have a concave circular shape to adhere closely to the outer wall of the heart.

[0022] The electroactive polymer may have a structure in which multiple layers are stacked. Effects of the invention

[0023] According to the cardiac assist device of the present invention, the following effects are achieved.

[0024] First, it can assist in the reduction of cardiac contractile function by compressing the heart externally with low power consumption while minimizing contact with blood.

[0025] Second, by securely attaching a cardiac assist device to the outer wall of the heart and applying direct pressure to the heart, the effect of alleviating heart failure symptoms can be enhanced.

[0026] Third, it can lower the risk of infection and effectively support heart function tailored to the characteristics of the heart, such as its size, shape, and condition.

[0027] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by a person skilled in the art from the description in the claims. Brief explanation of the drawing

[0028] FIGS. 1 and FIGS. 2 are perspective views of a cardiac assist device attached to the outer wall of the heart according to one embodiment of the present invention. Figure 3 shows the arrangement of several cardiac assist devices shown in Figure 1 placed on a sleeve. Figure 4 shows a disassembled view of a cardiac assist device according to one embodiment of the present invention. Figure 5 shows a spring coupled to the lower side of an electroactive polymer according to one embodiment of the present invention mounted in a housing. FIG. 6 is a perspective view showing the operation of a cardiac assist device attached to the outer wall of the heart according to one embodiment of the present invention. Figure 7 is a conceptual diagram showing the operation of the driving unit to explain the operation of the heart assist device of Figure 6. FIG. 8 illustrates the process of manufacturing an electroactive polymer for a cardiac assist device according to one embodiment of the present invention. Figure 9 shows the results of a performance test of a cardiac assist device according to one embodiment of the present invention. FIG. 10 shows the results of applying a cardiac assist device according to one embodiment of the present invention to a pig heart (Ex-vivo) to perform compression assistance and measuring the power consumption resulting from the compression assistance. Specific details for implementing the invention

[0029] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Throughout the specification, the same reference numerals refer to the same components.

[0030] The size or shape of components depicted in the drawings attached to this specification may be exaggerated for clarity and convenience of explanation. It should be noted that identical components in each drawing may be depicted with the same reference numeral. Furthermore, detailed descriptions of functions and configurations of known technology that are deemed to unnecessarily obscure the essence of the invention may be omitted.

[0031] The terms used herein are for describing specific embodiments and are not intended to limit the invention. As used herein, the singular form may include the plural form unless the context clearly indicates otherwise. Furthermore, throughout this specification, when a part is described as "comprising" a certain component, it means that it may include additional components unless specifically stated otherwise.

[0032] When it is stated that one component is "connected" or "connected" to another component, it should be understood that while it may be directly connected or connected to that other component, there may also be other components in between. Conversely, when it is stated that one component is "directly connected" or "directly connected" to another component, it should be understood that there are no other components in between. Other expressions used to describe relationships between components should be interpreted in the same way.

[0033] Terms such as top, bottom, upper surface, lower surface, or upper, lower, used in this specification are used to distinguish relative positions among components. For example, while the upper part of a drawing may be designated as the upper part and the lower part as the lower part for convenience, in practice, the upper part may be designated as the lower part and the lower part as the upper part without departing from the scope of the present invention.

[0034] Terms including ordinal numbers, such as "the first," "the second," etc., as described in this specification may be used to describe various components, but said components are not limited by said terms. These terms are used merely to distinguish that each component is a different component and are not bound by the order of manufacture; furthermore, the names may not match between the detailed description of the invention and the claims.

[0035] All terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains, unless otherwise defined. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this specification.

[0036] The symbols attached to each step are used to identify each step and do not indicate the order of the steps relative to one another; the steps may be performed differently from the specified order unless a specific order is clearly indicated in the context.

[0037] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0038] FIGS. 1 and 2 are perspective views of a cardiac assist device attached to the outer wall of a heart according to an embodiment of the present invention. FIG. 3 shows a plurality of cardiac assist devices shown in FIG. 1 arranged on a sleeve, and FIG. 4 shows a disassembled view of a cardiac assist device according to an embodiment of the present invention. FIG. 5 shows a spring coupled to the lower side of an electroactive polymer according to an embodiment of the present invention mounted on a housing. In FIG. 2, the appearance of the heart is omitted for ease of understanding.

[0039] Referring to FIGS. 1 to 4, a cardiac assist device (100) according to an embodiment of the present invention comprises an electroactive polymer (110) and a spring (120) coupled to the lower side of the electroactive polymer (110). When voltage is applied, the rigidity of the electroactive polymer (110) weakens, causing the compressed spring (120) to be restored and push the electroactive polymer (110) out, thereby transmitting force to the heart and causing cardiac compression. When voltage supply is interrupted, the rigidity of the electroactive polymer (110) strengthens, causing the spring (120) to be compressed and causing cardiac relaxation. The device also includes an interface (130) that transmits the force generated by the driving device to the heart to press the heart, and a central axis (140) that is connected so that the central parts of the spring (120), the electroactive polymer (110), and the interface (130) are connected to each other, and transmits the force generated by the driving device to the heart in a vertical direction.

[0040] Additionally, the cardiac assist device (100) may include an inner holder (150), a housing (160), an outer holder (170), and a sleeve (180). The electroactive polymer (110), interface (130), inner holder (150), housing (160), and outer holder (170) may be provided in a circular shape, for example, but are not limited thereto, and may be modified considering the condition, size, surface (outer wall), direction of force transmission, etc. of the heart.

[0041] A cardiac assist device (100) according to an embodiment of the present invention assists in reducing the contractile function of the heart by compressing the heart from outside the heart, and can reduce the risk of complications by minimizing direct contact with blood.

[0042] The number of heart assist devices (100) attached to the heart may vary depending on the size and condition of the heart.

[0043] The cardiac assist device (100) provides a non-blood contact and low-power solution that does not require anticoagulant therapy, thick drive lines, and bulky battery packs, and can be manufactured to fit the mechanical properties of the heart with a small and lightweight biomimetic design.

[0044] The heart assist device (100) can be placed in an optimal position by applying a biomimetic design to reflect differences in mechanical strength between parts of the heart.

[0045] The heart assist device (100) can assist in reducing the heart's contractile function by applying voltage to an electroactive polymer (110) (EAP) when the heart contracts (systole), and can induce normal relaxation of the heart by cutting off the voltage when the heart relaxes (diastolic).

[0046] The electroactive polymer (110) may be provided with a structure in which a stretchable electrode is coated on a dielectric elastomer so that the rigidity weakens when voltage is applied and strengthens when voltage supply is stopped. At this time, the stretchable electrode may be coated on the dielectric elastomer while the dielectric elastomer is stretched. The dielectric elastomer may include an acrylic elastomer.

[0047] The electroactive polymer (110) may be provided in a donut shape with a through hole formed in the center. An inner holder (150) is provided in the through hole formed in the center of the electroactive polymer (110), and the outer circumference of the electroactive polymer (110) may be supported by an outer holder (170).

[0048] The electroactive polymer (110) may be provided in a stacked structure, and each electroactive polymer (110) may be connected to a voltage source by an electrical connection line (115). The voltage source may include a battery or a power supply means that supplies a constant voltage.

[0049] The electrical connection lines (115) are provided to correspond to each electroactive polymer (110) and can be connected in pairs on both sides of the electroactive polymer (110). Depending on the stacked structure of the electroactive polymer (110), the electrical connection lines (115) can also be arranged in a stacked form.

[0050] Specifically, a plurality of electroactive polymers (110) can be stacked in such a manner that an inner holder (150) is provided between two outer holders (170) and an electrical connection line (115) is connected to both sides of the electroactive polymer (110).

[0051] Since the electroactive polymer (110) can operate with low power, it can maintain low power consumption (<0.3W), and thus the electrical connection line (115) that performs power supply can be designed to be very thin (e.g., OD = 0.3mm).

[0052] The electroactive polymer (110) can have a human-friendly and flexible structure. The process of manufacturing the electroactive polymer (110) according to an embodiment of the present invention will be explained in detail in FIG. 8.

[0053] The spring (120) may include a negative bias spring (NBS). Unlike a standard spring, a negative bias spring has the characteristic of becoming stronger as it returns to its original state. By utilizing this characteristic, pressure and volume changes, which are unique characteristics of the heart, can be effectively simulated. Efficient mechanical operation is possible by using a negative bias spring.

[0054] The heart assist device (100) can assist in compressing the heart by utilizing the force of the compressed negative bias spring returning to its original state (upwardly convex shape) when voltage is applied.

[0055] The spring (120) can be arranged in a stacked structure, taking into account the magnitude of the force to be transmitted to the heart.

[0056] The spring (120) can be manufactured by cutting a spring steel of a set thickness using a UV laser marking system.

[0057] Referring to FIGS. 4 and FIGS. 5, the spring (120) according to an embodiment of the present invention is provided with a symmetric curved shape in the shape of a double wave with respect to the center, so that symmetric deformation can occur simultaneously when voltage is applied or voltage supply is interrupted.

[0058] The spring (120) can be fitted onto the top of the housing (160), and the housing (160) has a symmetrical spring placement space (161) formed according to the shape of the spring (120).

[0059] The spring (120) placed in the housing (160) can be maintained with both ends clamped to the housing (160) by a fixing member (165) to maintain the center alignment and direction of the spring (120).

[0060] A central axis (140) is inserted into a coupling hole (162) formed in the center of the housing (160) and passes through a hole formed in the inner holder (150) of the spring (120) and the electroactive polymer (110) to be fastened (coupled) to the center of the interface (130).

[0061] When the spring (120) and the electroactive polymer (110) are used together, the movement of the electroactive polymer (110) can be induced in a direction perpendicular to the plane.

[0062] The spring (120) can be provided in an optimized form by considering one or more of the deformation shape, minimization of interference with the electroactive polymer (110), stiffness, and hysteresis.

[0063] The spring (120) according to an embodiment of the present invention is provided with a double wave-shaped symmetric curved surface with respect to the center, thereby providing symmetric deformation and minimizing interference with the electroactive polymer (110), so that the heart assist device (100) can maintain a compact form while reducing damage to the electroactive polymer (110).

[0064] In addition, since the spring (120) is provided with a double wave-shaped symmetrical curved surface, it can press the heart without moving to the sides when transmitting force to the heart in the vertical direction, thereby performing an effective heart compression assist role.

[0065] The interface (130) is located between the driving unit and the heart and can be formed in a shape that is sufficiently in contact with the surface (outer wall) of the heart for efficient power transmission.

[0066] The interface (130) can, for example, form a concave circular shape on the central side so as to be in close contact with the outer wall of the heart.

[0067] The interface (130) can be designed in shape and size by taking into account one or more of the shape, size, and condition of the heart so that the power of the driving unit can be evenly transmitted to the heart.

[0068] The interface (130) may have a structure in which a fiber-reinforced plastic (FRP) layer and a concave silicone layer are combined.

[0069] The interface (130) can be processed, for example, using a UV laser marking system, into a shape that adheres sufficiently to the surface of the heart.

[0070] The central axis (140) is connected so that the center of the spring (120), the electroactive polymer (110), and the interface (130) are connected to each other, and the force generated by the driving unit is transmitted to the heart in a vertical direction.

[0071] The central axis (140) may be in the shape of a stepped vertical bar, having a leading fastening part (141) that passes through a hole formed in the inner holder (150) of the spring (120) and the electroactive polymer (110) and is fastened to the center of the interface (130), and a lower support part (142) having a larger diameter than the leading fastening part (141) integrally provided.

[0072] The leading fastening part (141) can be provided in the form of a headless screw, for example, and can be in the form of a cylinder of the same diameter.

[0073] A non-lubricating bushing member (145) may be coupled to the leading coupling part (141). The bushing member (145) can act as a bearing that reduces friction between parts and smooths the reciprocating motion of the central axis (140).

[0074] The lower support (142) may be provided as a single-arm screw type for rotational axis and may be a cylindrical shape with a larger diameter than the leading lead fastening part (141).

[0075] The lower support member (142) is guided along the coupling hole (162) formed in the center of the housing (160) so that it can move vertically together with the driving unit when the driving unit operates. This prevents the risk of failure, such as the end of the spring (120) damaging the electroactive polymer (110), by causing the central axis (140) to become misaligned or misaligned when the driving unit operates.

[0076] The inner holder (150) is coupled to a through hole formed in the center of the electroactive polymer (110). The central axis (140) is coupled to the center of the spring (120) and the hole formed in the inner holder (150) so that the spring (120) and the electroactive polymer (110) can be connected to each other.

[0077] Since the electroactive polymer (110) is in the form of a thin film, it cannot be directly connected to the spring (120). Accordingly, in an embodiment of the present invention, an inner holder (150) is provided in a through hole formed in the center of the electroactive polymer (110), and the electroactive polymer (110) and the spring (120) can be connected by inserting a central axis (140) into the hole formed in the center of the spring (120) and the hole of the inner holder (150).

[0078] The housing (160) is combined with an outer holder (170) that supports the outer circumference of the electroactive polymer (110). A spring (120) is positioned on the upper side of the housing (160). The center of the spring (120) may be positioned on the central side of the housing (160), and a symmetrical spring placement space (161) is formed on the top of the housing (160) according to the shape of the spring (120) so that the spring (120) can be fitted.

[0079] A central axis (140) is inserted into a coupling hole (162) formed in the center of the housing (160) and passes through a hole formed in the inner holder (150) of the spring (120) and the electroactive polymer (110) to be fastened to the interface (130). The central axis (140) is guided along the coupling hole (162) formed in the center of the housing (160) and can move vertically together with the driving unit during operation.

[0080] The outer holder (170) can serve to support the electroactive polymer (110) so that it does not shrink when voltage is applied and the polymer expands upward. The coupling projection (172) protruding around the outer holder (170) can be coupled to the housing (160) by means of a fastening means (174) such as a bolt and a nut.

[0081] The sleeve (180) wraps around the outer surface of the housing (160) of the heart assist device (100), enveloping the heart and allowing the interface (130) to remain in contact with the heart.

[0082] The sleeve (180) can form a hole in the area where the central axis (140) is located, sized to fit the central axis (140), so as not to interfere with the reciprocating motion of the central axis (140).

[0083] The sleeve (180) may include a flexible thermoplastic polyurethane (TPU) sleeve. Although not illustrated, Velcro-type fasteners may be provided at both ends of the sleeve (180) to connect the ends of the sleeve (180) when attaching the sleeve (180) to the heart.

[0084] The length of the sleeve (180) can be designed considering the thickness of the drive unit and the circumference of the heart, and can be manually adjusted.

[0085] The sleeve (180) can enhance the effect of alleviating heart failure symptoms by allowing the heart assist device (100) to directly compress the outer wall of the heart.

[0086] FIG. 6 is a perspective view showing the operation of a cardiac assist device attached to the outer wall of the heart according to one embodiment of the present invention, and FIG. 7 is a conceptual diagram showing the operation of a driving unit to explain the operation of the cardiac assist device of FIG. 6.

[0087] Referring to FIGS. 6 and 7, when voltage is applied (EAP ON), the rigidity of the electroactive polymer (110) weakens (becomes softer), and the compressed spring (120) is restored, pushing the electroactive polymer (110) out of plane to create a motion that compresses the heart.

[0088] Conversely, when the voltage supply is interrupted (EAP OFF), the rigidity of the electroactive polymer (110) increases (becomes hard), and as the electroactive polymer (110) returns to its original state, the spring (120) is compressed, allowing the heart to relax (also called expansion or dilation).

[0089] That is, the heart assist device (100) can apply voltage to the electroactive polymer (110) when the heart contracts (systole) to assist in reducing the heart's contractile function, and cut off the voltage when the heart relaxes (diastolic) to induce normal relaxation of the heart.

[0090] As described above, in an embodiment of the present invention, the spring (120) may be implemented as a negative bias spring. A negative bias spring exhibits a unique behavior in which the restorative force increases first and then decreases when returning from a compressed state to its original uncompressed state. This is in contrast to a conventional spring, which applies a force that gradually decreases upon restoration.

[0091] Due to the characteristics of this negative bias spring, when the electroactive polymer (110) expands, the negative bias spring can apply a gradually increasing force to the heart, which can effectively mimic changes in the heart's pressure and volume while accommodating the rising ventricular pressure during systole. The negative bias spring can naturally reflect changes in the heart's pressure and volume while maintaining efficient displacement.

[0092] FIG. 8 illustrates the process of manufacturing an electroactive polymer for a cardiac assist device according to one embodiment of the present invention.

[0093] Referring to FIG. 8, to produce an electroactive polymer (110) according to an embodiment of the present invention, an acrylic elastomer is stretched horizontally and vertically and then attached to a temporary acrylic frame (S11, S21).

[0094] Next, a donut-shaped pattern mask is attached to the surface of the stretched elastomer, and a stretchable electrode is applied over it by spraying (S31).

[0095] The electrode can be applied by mixing silicone rubber, carbon black powder, and hexane in a set weight ratio.

[0096] Afterwards, the pattern mask is removed, and the holding frame attachment and wiring work is performed (S41, S51).

[0097] At this point, the pattern mask can be removed, and the electrode can be connected to the double-sided conductive tape. Then, the elastomer can be fixed in a sandwich form between two FRP holding frames, the excess elastomer can be cut off and cleaned, and the enamel-coated copper wire can be connected to the conductive tape.

[0098] FIG. 9 shows the results of a performance test of a cardiac assist device according to one embodiment of the present invention. The force is measured as the difference between the force of the solid line graph and the dotted line graph.

[0099] Referring to FIG. 9, configuration (1) (used in silicon phantom experiments) was observed to have a compression force of 5.78 N and a relaxation force of 5.48 N at a maximum displacement of 1.9 mm, while configurations (2) and (3) (ex-vivo experiments) showed maximum compression forces of 4.6 N at 1.45 mm and 6.64 N at 0.5 mm, respectively.

[0100] During the experiment, the cardiac assist device (100) operated by applying voltage during the systole phase to activate it and stopping the voltage supply during the diastole phase to deactivate it. To assist with both compression and relaxation, the maximum voltage (5.5 kV for configuration (1), 5.3 kV for configurations (2) and (3)) was applied for each configuration during compression, and 0 V was applied during relaxation.

[0101] In the contraction motion, the three configurations produced maximum forces of 5.97N, 4.49N, and 6.7N, respectively, which were very similar to the stiffness measurement results (within a margin of error of 5%), confirming consistent performance under various test conditions.

[0102] FIG. 10 shows the results of applying a cardiac assist device according to one embodiment of the present invention to a pig heart (Ex-vivo) to perform compression assistance and measuring the power consumption resulting from the compression assistance.

[0103] Referring to FIG. 10 (a) to (c), when a cardiac assist device (100) was applied to the mid and mid-base regions of the right ventricle of a pig heart, which differed in tissue stiffness by about 1.5 times, the discharge volume increased, and when 24 mL was injected, volume displacement increased by 1.11 times, 1.14 times, and 1.17 times compared to the control group at 0 kV, 4.5 kV, and 5.3 kV, respectively, and it was confirmed that the cardiac compression assist effect could be maximized through this.

[0104] In addition, when the power consumption of the heart assist device (100) according to the embodiment of the present invention was measured during the compression of a pig heart, it was confirmed to be less than 0.3W. Compared to the power consumption of a conventional heart compression device (20.5W) and the power consumption of a general LVAD (5W to 15W), it is a very low level, and it was confirmed that the heart assist device (100) demonstrates excellent energy efficiency even in a situation where the heart is compressed in actual tissue.

[0105] In this way, the cardiac assist device (100) of the present invention can assist in the deterioration of the heart's contractile function by compressing the heart from the outside with low power consumption while minimizing contact with blood, and can enhance the effect of alleviating symptoms of heart failure by applying direct pressure to the heart while being stably attached to the outer wall of the heart. In addition, it can reduce the risk of infection and effectively assist the heart according to characteristics such as the size, shape, and condition of the heart.

[0106] As described above, preferred embodiments of the present invention have been illustrated and described with reference to the drawings; however, the present invention is not limited to the specific embodiments described above. Various modifications are possible by those skilled in the art without departing from the essence of the invention as claimed in the patent claims, and such modifications should not be understood individually from the technical spirit or perspective of the present invention. Explanation of the symbols

[0107] 110: Electroactive polymer 115: Electrical connection line 120: Spring 130: Interface 140: Central axis 141: Lead connecting part 142: Lower support 150: Inner holder 160: Housing 165: Fixed member 170: Outer holder 172: Connecting protrusion 174: Means of fastening 180: Sleeve

Claims

Claim 1 A cardiac assist device comprising: a driving unit comprising an electroactive polymer and a spring coupled to the lower side of the electroactive polymer, wherein when voltage is applied, the stiffness of the electroactive polymer weakens, causing the compressed spring to be restored and push the electroactive polymer to perform cardiac compression, and when voltage supply is interrupted, the stiffness of the electroactive polymer strengthens, causing the spring to be compressed and cardiac relaxation to be performed; and an interface that transmits the force generated by the driving unit to the heart and presses the heart when voltage is applied. Claim 2 A cardiac assist device according to claim 1, wherein the electroactive polymer is provided with a structure in which a flexible electrode is coated on a dielectric elastomer such that the rigidity weakens when voltage is applied and strengthens when voltage supply is interrupted. Claim 3 A cardiac assist device according to claim 1, further comprising an electrical connection line connecting the electroactive polymer and the voltage source. Claim 4 A cardiac assist device according to claim 1, further comprising a central axis connected so as to be connected to the spring, the electroactive polymer, and the center of the interface, and configured to transmit a force generated by the driving unit to the heart in a vertical direction. Claim 5 In paragraph 4, the electroactive polymer is provided with an inner holder in a through hole formed in the center, and the central axis is coupled to the spring center and the inner holder to connect the spring and the electroactive polymer, forming a cardiac assist device. Claim 6 A cardiac assist device according to claim 5, further comprising a housing in which the spring is disposed and an outer holder coupled to the upper part of the housing and supporting the outer circumference of the electroactive polymer. Claim 7 A cardiac assist device according to claim 6, further comprising a sleeve that surrounds the outer surface of the housing and wraps around the heart, thereby maintaining the interface in contact with the heart. Claim 8 In claim 1, the interface is a cardiac assist device having a concave circular shape to adhere to the outer wall of the heart. Claim 9 In claim 1, the above-mentioned electroactive polymer is a cardiac assist device having a structure in which a plurality of layers are stacked.

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