Active implantable medical device

Abstract

The invention relates to an active implantable medical device, AIMD for short, comprising an implantable pulse generator, IPG for short, which is connected via an energy supply structure to an implantable electrical functional unit which is formed separately from the IPG and which comprises at least an electrode and / or an actuator system, with the electrode establishing electrical contact with an intracorporeal periphery, wherein the energy supply structure has at least one optical signal transmission path, and the IPG and the implantable electrical functional unit each comprise an optical transducer unit that is optically coupled to the optical signal transmission path. The invention is distinguished in that the at least one optical signal transmission path is designed in the form of an optically conductive fluid channel filled with a biocompatible, chemically inert liquid.

Description

[0001] Active implantable medical device

[0002] Technical field

[0003] The invention relates to an active implantable medical device, abbreviated AIMD, comprising an implantable pulse generator, abbreviated IPG, which is connected via an energy supply structure to an implantable electrical functional unit designed separately from the IPG, which has at least one electrode and / or actuator that comes into electrical contact with an intracorporeal periphery.

[0004] State of the art

[0005] Active implantable medical devices (AIMDs) are medical devices that, after being inserted into the human body, usually via a surgical procedure, remain there for at least 30 days. They serve the purpose of supporting the body's own organ and / or regulatory functions, the intracorporeal local application of medical agents, and / or the sensory monitoring of physiological parameters and / or biochemical components in body fluids. AIMDs generally have a self-contained housing containing at least one electrical power source and an associated electrical control unit, typically referred to as an implantable pulse generator (IPG). Depending on the type and function of the AIMD, the IPG is electrically connected to at least one electrode and / or actuator. The at least one electrode or actuator, for example,in the form of a blood pump or drug delivery unit, but is not necessarily often used as a separate unit for the IPG and via a [unclear context].

[0006] * in office shared with / office shared with energy, mostly electrical supply structure, functional unit connected to the electrical control unit.

[0007] AIMDs serve, for example, the purpose of electrical stimulation of local intracorporeal areas, such as for cardiac therapeutic defibrillation, pacemaker and resynchronization applications, for neurostimulation therapeutic measures, such as spinal cord stimulation, brain stimulation or vagus nerve stimulation.

[0008] Depending on the technical complexity of the implantable functional unit, a multitude of individual electrical connection lines are required for its electrical control and power supply. These lines are combined into a unified electrical supply structure and can extend between the IPG and the implantable functional unit over a length of a few centimeters to several decimeters. The unified electrical supply structure is preferably designed as a cable bundle with the thinnest possible cross-section and is connected to the IPG on one side and the implantable functional unit on the other. For reasons of minimally invasive implantation and also to allow for the possibility of separate, modular replacement of the IPG and the implantable functional unit, it is advantageous to design the electrical supply structure to be detachably and permanently connected to the IPG, e.g.,...via a plug-socket interface, as can be seen, for example, in the documents WO 2021 / 219344 A1 or US 2008 / 0077190 A1.

[0009] As an example of the many known AIMDs, the publication EP 3204 111 B1 may be mentioned, which discloses an implantable device for the site-selective acquisition of neuronal electrical signals propagating along at least one nerve fiber contained in a nerve fiber bundle, as well as for the selective electrical stimulation of the at least one nerve fiber. The implantable device comprises an implantable ganglion (IPG) and an implantable functional unit in the form of a cuff electrode arrangement, or cuff electrode, connected to the IPG via an electrical supply structure. The cuff electrode is designed to be wrapped around a nerve fiber bundle, preferably the vagus nerve. The cuff electrode provides a plurality of individual electrodes that, in the implanted state, make contact with the nerve fiber.The multitude of electrodes is each individually connected to an electrical conductor, all of which are grouped together in a conductor arrangement implemented in a foil-like, flat substrate. To minimize the cross-sectional area of ​​the electrical supply structure connecting the IPG and the cuff electrode, the electrical conductors implemented in the conductor arrangement must each be contacted with the thinnest possible conductor wire of the energy supply structure. This is achieved, for example, using a ceramic plate (see also publication WO 2018 / 224341 A1) on which the ends of the electrical conductors are connected, preferably by soldering or bonding, to a microflex contact. A further implantable electrical contact arrangement of this kind is described in publication WO 2024 / 056426 A1.

[0010] It is obvious that with an increasing degree of functional density, particularly on the part of the implantable functional unit, the number of electrical wires required for the operation, control, and power supply of the implantable functional unit increases accordingly. However, the higher the number of wires and the associated electrical contacts, the thicker and less flexible the electrical supply structure, i.e., the cable harness, becomes. This also leads to an increase in interactions and unavoidable side effects with the biological tissue, as well as an increased probability of cable harness breakage. Publication WO 2019 / 042553 describes a generic active implantable medical device in which light is used for optical signal and energy transmission between the implantable medical device and an energy supply structure.For this purpose, an optical fiber is used between the electrical supply structure and an AIMD, for example in the form of a cuff electrode. A photovoltaic cell is used within an optoelectronic module to convert electrical signals into optical signals and vice versa.

[0011] A comparable arrangement can be found in US patent 2005 / 0070987 A1, which describes an IPG in which electrical signals are converted into optical signals using light sources. An optical fiber array can be inserted into the IPG, the individual optical fibers of which are connected distally to photodiodes that convert the light signals into electrical signals, which are ultimately applied to electrodes.

[0012] After reviewing all other claims, it must be noted that the alternative feature disclosed in claim 5, namely that the optical signal transmission path is designed in the form of an optically conductive fluid channel, cannot be derived from the aforementioned cited documents.

[0013] Description of the invention

[0014] The invention is based on the objective of further developing an active implantable medical device, abbreviated AIMD, comprising an implantable pulse generator, abbreviated IPG, which is connected via an energy supply structure to an implantable electrical functional unit designed separately from the IPG, which has at least one electrode that comes into electrical contact with an intracorporeal periphery and / or an actuator, wherein the energy supply structure has at least one optical signal transmission path and the IPG and the implantable electrical functional unit each have an optical converter unit optically coupled to the optical signal transmission path, in such a way as to avoid the aforementioned disadvantages.In particular, measures are to be taken to modify the electrical supply structure in such a way that virtually unlimited scalability of the number of individual transmission paths between the IPG and the implantable functional unit becomes possible, without having to accept limitations with regard to the mechanical properties of the supply structure. The solution to the problem underlying the invention is specified in claim 1. Advantageously developing features of the invention are to be found in the dependent claims and the further description, in particular with reference to specific illustrated embodiments.

[0015] The AIMD solution according to the features of the preamble of claim 1 is characterized in that the at least one optical signal transmission path is designed in the form of an optically conductive fluid channel which is filled with a biocompatible, chemically inert liquid.

[0016] The proposed solution involves at least a partial substitution of the individual electrical wires in a known energy supply structure (i.e., an electrical supply structure) between an IPG and an implantable functional unit by at least one optical signal transmission path. This optical signal transmission path is designed as an optically conductive fluid channel through which optical signals can be transmitted. The use of an optical signal transmission path, compared to conventional wired electrical signal transmission, offers advantages, such as the elimination or significant minimization of conducted electrical impedances and the associated reduced susceptibility to interference from external energy fields.Light-based signal transmission between the IPG and the implantable functional unit enables the AIMD to be designed as an MRI-compatible implant. By utilizing established multiplexing techniques, a large number of individual and separable data transmission channels can be transmitted via a common optical signal transmission path, allowing for a reduced conductor cross-section in the form of an optically conductive fluid channel. This, in turn, reduces the disturbance or stress on the patient's own tissue along the conductor path between the IPG and the implantable functional unit. The optical signal transmission path is designed as an optically conductive fluid channel filled with a biocompatible, chemically inert fluid.The transmission of the fluid and the wavelength of the light passing through the optically conductive fluid channel are matched to minimize optical losses along the light path through the optically conductive fluid channel. Preferably, the biocompatible, chemically inert fluid is optically transparent. Fluorinert 77 (“Fluorinert” is a registered trademark of 3M) is a suitable example of a preferred fluid.

[0017] In particular, when using an optical fluid channel filled with fluid, no material-related fatigue occurs, which significantly increases the service life of the AIMD in general and the energy supply structure in particular compared to wired supply structures, especially since the latter are subject to continuous wire deformation due to the patient's own intracorporeal movements. In the case of an optical fluid channel, such intracorporeal movements have no lasting effect on the fluid contained within the channel.

[0018] To control the implantable functional unit using the electrical control signals generated within the IPG, an optical converter unit is provided within the IPG. This unit is connected to an electrical control circuit located within the IPG, which is typically implemented as a chip-based ASIC circuit. The optical converter unit, designed as an electrically controllable light source, e.g., in the form of an LED or a semiconductor laser, is capable of converting the multitude of control signals required for the operation of the implantable functional unit and generated by the electrical control circuit into light or photons. A multiplexer, located between the electrical control circuit and the optical converter unit, processes the numerous different control signals generated by the electrical control circuit as parallel control signal data streams. Each of these data streams is used to control, for example, the implantable functional unit.Each electrode attached to the implantable functional unit serves as the source of the electrical signal. The resulting data stream is then converted into a serial control signal. This serial control signal is fed to the optical converter unit, either directly or via an intermediate amplifier unit, such as an operational amplifier. The optical converter unit then converts the electrical control signals into optical control signals, which are subsequently coupled into at least one optical signal transmission path of the optical supply structure for transmission to the implantable functional unit.

[0019] On the receiving side, i.e., at the location of the implantable functional unit, an optical converter unit, e.g., in the form of a photodiode, is coupled to the optical signal transmission path to convert the optical control signals into a serial electrical control signal data stream. This data stream is then fed to an operational amplifier, preferably for amplification. A downstream demultiplexer recovers the multitude of different control signals originally generated by the electrical control circuit, each in the form of parallel control signal data streams, and selectively applies them to the electrodes arranged in the implantable functional unit.

[0020] Preferably, the optical signal transmission path of the energy supply structure is bidirectional, so that electrical signals from the implantable functional unit, e.g., in the form of sensor signals, can also be transmitted to the IPG for further analysis and forwarding. For this purpose, the implantable functional unit requires a circuit for converting electrical signals into optical signals, as described above in connection with the IPG. Furthermore, the IPG must be equipped with all the circuit components necessary for the reverse conversion of optical signals into electrical signals, as described above in connection with the implantable functional unit.

[0021] All components required for converting electrical control signals into optical control signals and vice versa—i.e., optical converters, operational amplifiers, and multiplexers / demultiplexers—are preferably implemented as integrated circuits (ICs) to minimize space and power consumption at the location of the implantable functional unit (IPG), and especially at the location of the implantable functional unit. For example, a separate power supply from the IPG's electrical energy storage unit to the implantable functional unit is required to provide voltage and power to the IC at the implantable functional unit, particularly since there is no dedicated electrical energy storage unit at the implantable functional unit, not least due to space constraints.

[0022] In principle, a direct optical energy transfer to and supply of the integrated circuit (IC) via a high-power diode attached to the IPG would be advantageous. The light from this diode could then be transmitted to the IC on the implantable functional unit via the optical signal transmission path. However, coupling losses are problematic in this context, as they are higher in power optics than the ohmic resistance of two metallic conductors. Furthermore, power diodes also generate heat, which is problematic in the body.

[0023] For this reason, a preferred embodiment provides, in addition to at least one optical signal transmission path along the power supply structure, at least two electrical conduction paths in the form of two electrical wires, via which the IC attached to the implantable functional unit can be directly supplied with electrical energy. The two electrical wires do not impair, or only insignificantly impair, the advantages mentioned in connection with optical signal transmission, but contribute considerably to the functionality and safety of the IC at the location of the implantable functional unit.

[0024] In a further preferred embodiment, the IPG and the implantable electrical functional unit each have an electrode unit that additionally electrically contacts the optical signal transmission path. This enables the unidirectional or bidirectional transmission of electrical signals and / or electrical energy between the IPG and the implantable electrical functional unit, in addition to the optical signal and energy transmission. This requires, in addition to the liquid being transparent (preferably optically transparent) to the respective wavelength of light used, electrical conductivity. Suitable liquids for this purpose include, for example, sterilized water, FC77, biocompatible ionic liquids (bio-ILs), such as choline acetate, ion gels, and hydrogels.

[0025] The electrode units, which additionally electrically contact the optical signal transmission path, are each connected to a controllable voltage and / or current source known to those skilled in the art for the purpose of electrical signal application, and to a voltage and / or current meter or sensor for signal detection. In this way, in addition to the light signals transmitted via the optical signal transmission path, electrical signals can be transmitted by means of the liquid, which is transparent to the light signals and also possesses electrical conductivity, thereby significantly increasing the amount of information and / or energy that can be transmitted.

[0026] As an alternative to or in combination with the electrode units described above, which electrically contact the optical signal transmission path, a further embodiment provides a sound transducer unit acoustically coupled to the optical signal transmission path on both the IPG and the implantable electrical functional unit. The sound transducer units, preferably in the form of a piezoceramic transducer, are each connected to an electrical control unit that enables the transducers to both transmit and couple sound waves into the biocompatible, chemically inert liquid, as well as to couple sound waves out of the biocompatible, chemically inert liquid and detect them.The biocompatible, chemically inert liquid, which is optionally electrically conductive, has a dynamic viscosity of at least 1 mPa s, comparable to water, but preferably higher viscosity properties, e.g., comparable to oil or honey, i.e., up to 9.5 ■ 10. 5 mPa s. Although the term "liquid" is not technically entirely correct for flowable, highly viscous media such as honey- or syrup-like media, the use of this term will be maintained in the following, which should therefore also include those mentioned above.

[0027] By coupling sound waves into and out of the biocompatible, chemically inert liquid that completely fills the optical signal transmission path, mechanical energy in the form of sound waves is transmitted along the biocompatible, chemically inert liquid in addition to the optical signals and light energy; the liquid is optionally also capable of transmitting electrical energy.

[0028] Brief description of the invention

[0029] The invention is described below by way of example, without limiting the general concept of the invention, with reference to the drawing. It shows:

[0030] Fig. 1 AIMD consisting of an IPG and an implantable functional unit designed as a cuff electrode placed around a nerve cord.

[0031] Ways to implement the invention, industrial applicability

[0032] Figure 1 depicts a solution AIMD consisting of an IPG and an implantable functional unit IF connected to the IPG via an energy supply structure 1. The IF comprises a cuff electrode 2 wrapped around a nerve fiber 3. The cuff electrode 2 has a plurality of individual electrodes (not shown) that locally and separately contact the surface of the nerve fiber 3 to electrically stimulate individual, selected nerve fibers and to selectively detect electrical neuronal signals propagating along selected nerve fibers. Each individual electrode of the cuff electrode 2 is connected to an electrical conductor 4, which extends from the cuff electrode 2 in a conductor arrangement 4' and is connected at its end to an electrical contact 6 on the surface of a ceramic plate 5 opposite the cuff electrode 2.The cuff electrode 2 and the conducting electrical conductors 4, which are contacted on the ceramic plate 5, constitute the implantable functional unit IF.

[0033] An integrated circuit (IC) is mounted on the underside of the ceramic plate 5, comprising an optical converter 7, an operational amplifier 8, and a multiplexer / demultiplexer 9. The optical converter 7, arranged within the IC and preferably consisting of a light-detecting photodiode and / or a light source, e.g., an LED or semiconductor laser, couples with minimal or no loss to an optical signal transmission path 10 of the power supply structure 1. The optical signal transmission path 10 is designed as a fluid-filled, optically conductive fluid channel 11.

[0034] The IPG encloses, within a fluid-tight housing, at least one electrical energy storage device 12, which is typically rechargeable without contact via inductive coupling, and an electrical control circuit 13 in which all control signals required for the safe operation of the cuff electrode 2 are generated and monitored. Additionally, an integrated circuit (IC) is arranged within the IPG, which is connected on one side to the electrical control circuit 13 and on the other side to the optical signal transmission path 10. The integrated circuit (IC) comprises, like the integrated circuit (IC) arranged on the underside of the ceramic plate 5, an optical converter unit 7', an operational amplifier 8', and a multiplexer / demultiplexer 9'. For electrical voltage or...The integrated circuit IC (IC) within the IPG is powered by the electrical energy storage device 12 located within the IPG, which is connected to the IC via the electrical control circuit 13. Two electrical conductors 14 run along the energy supply structure 1 to provide electrical voltage and power to the integrated circuit IC located on the implantable functional unit IF. These conductors supply electrical energy from the electrical energy storage device located within the IPG to the optical converter unit 7, the operational amplifier 8, and the multiplexer / demultiplexer 9. Furthermore, the conductors are designed to be so thin and flexible that they do not have a lifespan-limiting effect on the energy supply structure 1.

[0035] By providing the integrated circuits IC and IC on both the IPG and the implantable functional unit IF, the electrical control signals generated by the IPG can be converted into optical control signals and transmitted via the optical signal transmission path 10 of the energy supply structure 1 to the implantable functional unit IF, where they are converted back into electrical control signals. These signals are ultimately applied as therapeutically effective stimulation signals to an intracorporeal structure, e.g., along nerve tract 3. Conversely, the implantable functional unit IF can be used to process endogenous electrical signals, e.g., ECG or neuronal signals, etc.After conversion to optical signals by means of the integrated circuit (IC), the signals are transmitted via the optical signal transmission path 10 of the power supply structure 1 to the IPG, where they are converted back into electrical signals by the electrical control circuit 13 and can be transmitted for further use and evaluation, e.g., to an extracorporeal unit. Such data transmission from the IPG to an extracorporeal unit is carried out contactlessly, preferably by means of inductive coupling, in a manner known per se.

[0036] The decentralized arrangement and design of the integrated circuits (ICs) on both the IPG and the implantable functional unit (IF), along with the use of optical signal transmission for all control and sensor signals, minimizes electrical impedances. This results in lower energy consumption and thus longer operating times for the AIMD before recharging. Furthermore, the AIMD's design, with its very short and minimal number of electrical signal paths, offers improved MRI compatibility, as the strongest effect of the alternating magnetic fields in an MRI scanner is caused by the length of an electrical cable. This could pave the way for an MRI-compatible implant.

[0037] In an advantageous extension or supplement to the AIMD described above, see Figure 1, an electrically contacting electrode unit 15, 15' is additionally attached to the IPG and the implantable functional unit IF, next to the optical transducer unit 7 and 7' respectively, which couples electrically to the biocompatible, chemically inert liquid within the optical signal transmission path (10).

[0038] In the same way as the electrical control of the optical transducer units 7, 7', the electrically contacting electrode units 15, 15' with the integrated circuits IC and IC are connected to both the IPG and the implantable functional unit IF. Thus, the electrical control signals generated with the aid of the IPG can be transmitted via the electrode unit 15', which is electrically contacted with the biocompatible, chemically inert liquid, to the implantable functional unit IF via the optical signal transmission path 10 of the energy supply structure 1. There, they are applied directly or indirectly as therapeutically effective stimulation signals to an intracorporeal structure, e.g., along the nerve tract 3, via the electrode unit 15, which is electrically contacted with the biocompatible, chemically inert liquid.

[0039] Conversely, the implantable functional unit IF can be used to amplify sensor-detected endogenous electrical signals, e.g., ECG or neuronal signals, etc., and then transmit them via the electrode unit 15, which electrically contacts the biocompatible, chemically inert liquid, to the IPG via the optical signal transmission path 10 of the energy supply structure 1, where they are analyzed within the framework of the electrical control circuit 13 and can be transmitted to an extracorporeal unit for further use and evaluation, e.g.

[0040] In a further advantageous extension or addition, see Figure 1, a sound transducer unit 16, 16', preferably in the form of a piezoceramic oscillator, is additionally arranged on the IPG and on the implantable functional unit IF, next to the optical transducer unit 7 or 7' respectively and optionally next to the optionally provided electrically contacting electrode units 15, 15', which acoustically couples to the biocompatible, chemically inert liquid within the optical signal transmission path (10).

[0041] In the same way as the electrical control of the optical transducer units 7, 7', the sound transducer units 16, 16' with the integrated circuits IC and ICs are connected to both the IPG and the implantable functional unit IF. Thus, the electrical control signals generated with the aid of the IPG can be transmitted as sound waves via the optical signal transmission path 10 of the energy supply structure 1 to the implantable functional unit IF by means of the sound transducer unit 16', which acoustically couples to the biocompatible, chemically inert fluid. There, they are converted back into electrical signals by means of the sound transducer unit 16, which acoustically couples to the biocompatible, chemically inert fluid. These electrical signals are then applied as therapeutically effective stimulation signals to an intracorporeal structure, e.g., along the nerve tract 3.

[0042] Conversely, the implantable functional unit IF can be used to amplify sensor-detected endogenous electrical signals, e.g., ECG or neuronal signals, etc., and then transmit them as sound waves to the IPG via the acoustic transducer unit 16, which contacts the biocompatible, chemically inert fluid. After being converted back into electrical signals, these signals are analyzed within the framework of the electrical control circuit 13 and can be transmitted to an extracorporeal unit, for example, for further use and evaluation.

[0043] In this way, signals and energy in three independent energy forms—optical, acoustic, and electrical—can be transmitted bidirectionally between the IPG and the implantable functional unit IF using a single liquid transmission medium that is not subject to degradation.

[0044] 1. Energy supply structure

[0045] 2 Cuff electrode

[0046] 3 nerve strand

[0047] 4 electrical conductors

[0048] 4' conductor track arrangement

[0049] 5 ceramic plates

[0050] 6 electrical contact

[0051] 7. Optical converter unit

[0052] 8, 8' operational amplifier

[0053] 9, 9' multiplexer / demultiplexer

[0054] 10 optical signal transmission path

[0055] 11 optically conductive fluid channel

[0056] 12 electrical energy storage devices

[0057] 13 electrical control circuit

[0058] 14 electrical conductors

[0059] 15, 15' electrically contacting electrode unit 16, 16 transducer unit

[0060] AIMD active implantable medical device IPG Implantable Pulse Generator

[0061] IC, IC' integrated circuit

[0062] IF implantable functional unit

Claims

Patent claims 1. Active implantable medical device, abbreviated AIMD, comprising an implantable pulse generator, abbreviated IPG, which is connected via an energy supply structure (1) to an implantable electrical functional unit (IF) separately configured from the IPG, which has at least one electrode that makes electrical contact with an intracorporeal periphery and / or an actuator, wherein the energy supply structure (1) has at least one optical signal transmission path (10) and the IPG and the implantable electrical functional unit (IF) each have an optical converter unit (7, 7') optically coupled to the optical signal transmission path (10), characterized in that the at least one optical signal transmission path (10) is designed in the form of an optically conductive fluid channel (11) which is filled with a biocompatible, chemically inert liquid.

2. AIMD according to claim 1 , characterized in that the optical converter unit (7, 7') is able to convert optical signals into electrical signals and vice versa.

3. AIMD according to claim 1 or 2, characterized in that the optical converter unit (7. 7') is a light-sensitive photodiode and / or a light source in the form of an LED or a semiconductor laser.

4. AIMD according to claim 3, characterized in that the optical converter unit (7, 7') together with an amplifier (8, 8') and a multiplexer / demultiplexer (9, 9') is designed as an integrated circuit (IC, IC).

5. AIMD according to any one of claims 1 to 4, characterized in that at least one electrical line (14) runs along the energy supply structure (1), which is connected to an electrical energy storage device (12) arranged in the IPG and serves to supply electrical energy to at least the optical transducer unit (7) attached to the implantable functional unit (IF).

6. AIMD according to any one of claims 1 to 5, characterized in that the implantable functional unit (IF) is a cuff electrode (2) that can be wrapped around a nerve strand (3) and provides a plurality of electrodes which, in the implanted state, contact the nerve strand (3), that the plurality of electrodes is each individually connected to an electrical conductor (4), and that the plurality of electrical conductors (4) is connected to the optical transducer unit (7).

7. AIMD according to any one of claims 1 to 5. characterized in that the implantable functional unit (IF) is an electrode unit of a pacemaker, defibrillator or neurostimulator.

8. AIMD according to any one of claims 1 to 7, characterized in that the IPG and the implantable electrical functional unit (IF) each have a sound transducer unit acoustically coupled to the optical signal transmission path (10).

9. AIMD according to one of claims 1 to 8, characterized in that the IPG and the implantable electrical functional unit (IF) each have an electrode unit electrically contacting the optical signal transmission path (10).

10. AIMD according to any one of claims 1 to 9, characterized by the fact that the biocompatible, chemically inert liquid is optically transparent and electrically conductive.

11. AIMD according to any one of claims 1 to 10, characterized by the fact that the biocompatible, chemically inert liquid has a dynamic viscosity q of 1 to 9.5 10 5 mPa s possesses.

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