WO2012013201A1 - Dispositif à électrodes implantable, en particulier pour un stimulateur cardiaque - Google Patents

Dispositif à électrodes implantable, en particulier pour un stimulateur cardiaque Download PDF

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Publication number
WO2012013201A1
WO2012013201A1 PCT/EP2010/004586 EP2010004586W WO2012013201A1 WO 2012013201 A1 WO2012013201 A1 WO 2012013201A1 EP 2010004586 W EP2010004586 W EP 2010004586W WO 2012013201 A1 WO2012013201 A1 WO 2012013201A1
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WO
WIPO (PCT)
Prior art keywords
electrode device
magnetic field
coil
electrode
energy
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PCT/EP2010/004586
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English (en)
Inventor
Erhard Kisker
Original Assignee
Universität Duisburg-Essen
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by Universität Duisburg-Essen filed Critical Universität Duisburg-Essen
Priority to PCT/EP2010/004586 priority Critical patent/WO2012013201A1/fr
Priority to PCT/EP2011/003763 priority patent/WO2012013342A2/fr
Publication of WO2012013201A1 publication Critical patent/WO2012013201A1/fr

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00—Electrotherapy; Circuits therefor
    • A61N1/18—Applying electric currents by contact electrodes
    • A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
    • A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
    • A61N1/372—Arrangements in connection with the implantation of stimulators
    • A61N1/375—Constructional arrangements, e.g. casings
    • A61N1/3756—Casings with electrodes thereon, e.g. leadless stimulators
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00—Electrotherapy; Circuits therefor
    • A61N1/18—Applying electric currents by contact electrodes
    • A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
    • A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
    • A61N1/372—Arrangements in connection with the implantation of stimulators
    • A61N1/37205—Microstimulators, e.g. implantable through a cannula
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00—Electrotherapy; Circuits therefor
    • A61N1/18—Applying electric currents by contact electrodes
    • A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
    • A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
    • A61N1/372—Arrangements in connection with the implantation of stimulators
    • A61N1/378—Electrical supply
    • A61N1/3787—Electrical supply from an external energy source
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
    • H02J50/10—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
    • H02J50/20—Circuit arrangements or systems for wireless supply or distribution of electric power using microwaves or radio frequency waves
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/007—Regulation of charging or discharging current or voltage
    • H02J7/00712—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2310/00—The network for supplying or distributing electric power characterised by its spatial reach or by the load
    • H02J2310/10—The network having a local or delimited stationary reach
    • H02J2310/20—The network being internal to a load
    • H02J2310/23—The load being a medical device, a medical implant, or a life supporting device
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters

Definitions

  • Implantable electrode device in Particular for a Cardiac Pacemaker
  • the present invention relates to an implantable electrode device, a stimulation system and a method for operating at least two implantable electrode devices.
  • the focus is primarily on a cardiac pacemaker.
  • the present invention is not restricted to this particular solution, but in general can be applied to other stimulation devices which operate electrically and in particular deliver electrical impulses for stimulation.
  • Cardiac pacemakers stimulate the heart beat by means of electrical impulses which are introduced into the muscle tissue of the heart.
  • a cardiac pacemaker is usually implanted, for example, near the shoulder of the thoracic cage, at least one probe or electrical lead being guided from the implanted cardiac pacemaker via a vein into the atrium or the chambers of the heart and anchored there.
  • the electrical lead is problematical or disadvantageous. This runs over a length of about 30 cm in the blood circulation system and can thereby cause undesirable or even fatal physical reactions.
  • the risk of failure of the probes or leads due to material fatigue as a result of the severe me- chanical stressing during body movements is particularly high. Another complication frequently encountered is dislocation of the probes triggered by movements of the patient.
  • US 5,41 1 ,535 A discloses a cardiac pacemaker with an implantable control de- vice and a separate electrode device. Electrical signals of 10 MHz to a few GHz in particular are transmitted without wires between the control device and the electrode device for controlling the electrode device. The actual power supply of the electrode device is provided via a battery integrated in the electrode device. Such cardiac pacemakers with a separate electrode device have not been widely accepted so far. This may be because the electrode device is of a considerable size and has a limited operating time because of the battery.
  • JP 06 079 005 A discloses an implantable cardiac pacemaker whose battery can be inductively recharged from outside via a coil.
  • US 5,405,367 A discloses an implantable microstimulator.
  • the microstimulator comprises a receiving coil , an integrated circuit and electrodes. It can be supplied with energy and with control information via an external magnetic field generated by an external coil having an allocated oscillator and an allocated stimulation control device.
  • Such a microstimulator is not suitable for cardiac stimulator or as a cardiac pacemaker since it is relatively large for sufficient capacity and requires an external energy supply.
  • WO 2006/045075 A l relates to various configurations of systems that employ leadless electrodes to provide pacing therapy.
  • a single magnetic pulse is used to generate an electrical pulse in an electrode device. This is problematic, in particular due to magnetic saturation.
  • US 2009/0024180 A l discloses a stimulation system comprising an implantable electrode device. The electrode device is supplied with energy and controlled in an exclusively wireless manner via a time-variable magnetic field generated by an implanted control device.
  • Stimulation systems comprising a wireless transmission of energy known in the art are limited in performance by their power consumption. Furthermore, these systems may suffer from a low stimulation efficiency.
  • the object of the present invention is to provide an electrode device, a stimulation system or a method, wherein the reliability, efficiency and/or effectivity can be improved.
  • an implantable electrode device for a stimulation system according to claim 1 by a stimulation system according to claim 12 or by a method for operating at least two implantable electrode devices according to claim 16.
  • Advantageous embodiments are subject of the subclaims.
  • an implantable electrode de- vice for a stimulation system preferably a cardiac pacemaker.
  • the electrode device is adapted for generating electrical impulses, wherein the electrode device is configured as a wireless and/or compact structure unit and can be supplied with energy and/or controlled by means of a time-varying magnetic field.
  • the electrode device can be controlled by means of the time-varying magnetic field additionally or alternatively to the supply of energy by such a field.
  • magnetic field preferably covers electro-magnetic fields or waves.
  • fields, waves or the like with any kind of magnetic component can be “magnetic fields” in the sense of the present invention as well.
  • the electrode device comprises a rectifier, wherein, preferably, the rectifier comprises semiconductor switches with a control port for commutation.
  • these semiconductor switches with control ports are transistors, in particular MOSFETs, wherein the control port an be their gate.
  • semiconductor switches are IGBTs, four-layer-elements or any kind of semiconductor devices with controllable impedance.
  • the rectifier comprises semiconductor switches in a (H-) bridge configuration.
  • the term "commutation" preferably is understood as switching an output from one to another (input-) phase, e.g.
  • a rectifier comprising semiconductor switches leads to an efficient rectifying i .e. low losses, as semiconductor switches can provide a low impedance, in particular at low operation voltages.
  • the electrode device comprises a delay means for generating a delay between reception of energy and the generation and/or delivery of at least one of the electrical impulses.
  • a time for generating and/or for emitting and/or delivering an electrical impulse can be defined more precisely. This is advantageous for an exact and reliable stimulation.
  • the electrode device comprises a protection means to prevent or block generation or delivery of electrical impulses for a time span after a first electrical impulse has been generated.
  • a protection means to prevent or block generation or delivery of electrical impulses for a time span after a first electrical impulse has been generated.
  • a second aspect of the present invention that can be realized independently as well , relates to a stimulation system, in particular a cardiac pacemaker, comprising an implantable control device and at least a first implantable electrode device according to the first aspect of the present invention .
  • a stimulation system can be much more efficient and reliable, in particular benefiting from the advanced electrode device. With improvements in efficiently, portable systems can provide an extended life time until recharge is necessary . In addition, a better and/or more powerful stimulation can be reached.
  • the stimulation system can comprise at least a second electrode device which may be an electrode device according to the first aspect of the present invention also, but does not need to.
  • the second electrode device is implantable and configured as a wireless and/or compact structure unit an can be supplied with energy and, preferably, controlled by means of a vary magnetic field.
  • the second electrode device With at least two electrode devices it is possible to realize a much more efficient stimulation, in particular by stimulating different areas. It can be useful to realize a time delay between electrical impulses of the different electrode devices. Hence, it can be particularly advantageous to make use of the delay means of the at least one electrode device according to a first aspect of the present invention.
  • a method for operating at least two implantable electrode devices is provided. These devices preferably are used in a cardiac pacemaker system and/or for generating electrical impulses.
  • the electrode devices are supplied with energy exclusively in a wireless manner, and electrical impulses are generated by the electrode devices with a particular time delay.
  • the time delay is controlled and/or modified by means of the magnetic field, in particular wherein the electrode devices are triggered by magnetic fields of different strength. Controlling or modifying the time delay between the electrical impulses generated by each of the electrode devices can lead to an optimized stimulation result.
  • an implantable electrode device comprises a delay means as well as protection means, wherein both of them can make use of a common switch in series with the electrode, preferably a semiconductors switch, in particular a MOSFET.
  • a supervisory component can be adapted to control the switch for the delay and/or the protection functions.
  • the delay means and/or the protection means can be realized separately, too.
  • Another aspect of the present invention resides in the fact that the implantable electrode device for generating electrical impulses can be supplied with energy and/or preferably directly controlled in an exclusively wireless or leadless manner by means of a time-varying magnetic field.
  • the magnetic field is preferably generated by an, in particular implantable, control device so that an external controller can be avoided. This is particularly desirable when the stimulation system is used as a cardiac pacemaker and is sub- 15 stantially more reliable in use than control by an external , i .e. non-implanted, control device.
  • the electrode device is particularly preferably controlled directly by the time- varying magnetic field.
  • "Direct" control is to be understood in the present patent 0 application in that the electrical impulses are generated in direct dependence on the magnetic field, for example, depending on the magnitude of the magnetic field, the polarity of the magnetic field and/or the rate of change of the magnetic field, in particular without any active electronic component being interposed in the electrode device. Consequently, in the preferred direct control , electrical im- 5 pulses or stimulations are generated so that they are only temporally correlated to the magnetic field. This also permits a very simple and in particular compact structure of the electrode device and/or a very reliable defined control .
  • Another aspect of the present invention includes configuring the electrode device 30 such that an electrical impulse is only generated when a minimum field strength of the magnetic field is exceeded.
  • This very simply measure permits reliable control which in particular is not sensitive to interference when the minimum field strength is selected as suitably high, since strong magnetic fields occur very rarely but alternating electromagnetic fields having various frequencies are very 35 common.
  • a first electrode device can be configured to generate and electrical impulse, if a first, minimum field strength of the magnetic field is exceeded and a second electrode device is configured to generate an electrical impulse, if a sec- ond minimum field strength of the magnetic field is exceeded.
  • the first and the second minimum field strength can be different such that the electrical impulses can be controlled independently using magnetic fields of different strength.
  • a time delay between two or more electrical impulses of different electrode devices can be obtained and/or controlled.
  • the electrode device must first be activated before a further electrical impulse can be generated.
  • This activation is effected in particular by another signal , preferably by the opposite field direction of the magnetic field, shortly before triggering and generating the next electrical impulse.
  • two-stage triggering or signal generation is required to generate an electrical impulse by means of the electrode device.
  • This two-stage property results in particularly reliable triggering, i.e., not sensitive to interference.
  • the protection means can be used to prevent or block the generation and/or delivering of an electrical impulse, in particular by deactivating a trigger function, by decoupling electrodes or the like.
  • a coil device having a high number of turns that is a coil having many turns, is used to generate an electrical impulse having a high voltage of at least 0.5 V, preferably substantially 1 V or more and having a relatively long duration of at least 0.05 to 2 ms.
  • the coil device can in particular have a soft-magnetic or ultrasoft magnetic core.
  • the high number of turns, in particular at least 1 ,000 turns, of a suitably insu- lated wire made of, for example, Cu, Ag or Al in particular having a diameter of about 0.01 to 0.1 mm permits the generation of a strong and long electrical impulse in said sense.
  • no continuous or persistent, for example, sawtooth-shaped ascending magnetic field pulse is generated by the control device but a plurality of short magnetic field pulses, in particular so that the core of the coil device or electrode device always varies its magnetization far below the saturation state.
  • a minimal energy consumption can be achieved, in particular if the largest possible temporal flux variation takes place in the core of the coil device or electrode device throughout the entire duration of the stimulating pulse (optionally a contiguous sequence of electrical impulses of the electrode device; in the present invention, this sequence is considered as a single electrical impulse for stimula- tion). This can be achieved by short magnetic field pulses.
  • the magnetic field pulses can be unipolar or bipolar when using soft-magnetic core material .
  • bistable materials in particular Wiegand or pulsed wires
  • bipolar magnetic fields must be used.
  • an implantable stimulation device comprises the magnetisable, preferably ferromagnetic element, the magnetization of the element being varied by an external or varying magnetic field so that the magnetic leakage flux of the element results in the desired electrical stimulation or generation of an electrical impulse in the surrounding tissue. This permits a particularly simple structure where electrical contact electrodes are omitted and the associated problems can be avoided.
  • the proposed electrode device or another electrode device can be used alterna- tively or additionally to convert the self-action of the heart, in particular a movement of the heart and/or electrical activity of the heart, into a magnetic impulse or another, in particular, electrical signal which can preferably be detected by the stimulation system or another receiving unit.
  • the implantable electrode device is used in particular for generating electrical signals to stimulate the heart.
  • the present invention is not restricted to this. Rather, the electrode device can generally generate any type of electrical impulse(s) or electrical signals in the human or animal body.
  • the terms "electrode device” and “stimulation system” should ac- cordingly be understood in a very general sense so that other applications and uses, such as for example to influence the brain, can also be understood.
  • Fig. 1 is a schematic diagram of a proposed stimulation system comprising a control device and an electrode device in the implanted state according to this invention
  • Fig. 2 is a schematic view of the control device according to this invention
  • Fig. 3 is a schematic view of the electrode device according to this invention.
  • Fig. 4 is a block diagram of the electrode device according to this invention.
  • Fig. 5 is a schematic section view of a core element of the electrode device according to this invention.
  • Fig. 6 is a schematic diagram of a magnetization curve of a coil device of the electrode device according to this invention
  • Fig. 7 is a schematic diagram of the time profile of a magnetic field and an induced voltage according to this invention
  • Fig. 8 is a schematic section of another electrode device according to this invention.
  • Fig. 9 is a schematic section of another stimulation or electrode device according to this invention.
  • Fig. 10 is a schematic block diagram of a further proposed stimulation sys- tern comprising control device and electrode device as well as comprising a charging device according to this invention
  • Fig. 1 la-c is a schematic diagram of the time profile of trigger pulses, a generated magnetic field and a generated electrical impulse according to this invention
  • Fig. 12 illustrates an example of preferred magnetization according to this invention
  • Fig. 13 is a diagram for choosing optimized operation parameters
  • Fig. 14 is a schematic diagram of a preferred circuit of the electrode device according to the present invention.
  • Fig. 15 is a block diagram of the electrode device
  • Fig. 16 is a rectifier circuit of the electrode device
  • Fig. 17 is a schematic of a rectifier circuit of the electrode device
  • Fig. 18 is a block diagram of the electrode device
  • Fig. 19 is a block diagram of the electrode device.
  • Fig. 20 is a timing diagram for the supervisory component.
  • Figure 1 is a schematic sectional view of a proposed stimulation system 1 which is in particular configured as or works as a cardiac pacemaker in the example shown.
  • the stimulation system 1 can additionally or alternatively operate as a defibrillator or be used for other purposes and at other locations in the human or animal body.
  • the stimulation system 1 preferably comprises an implantable control device 2 and an implantable electrode device 3 separate therefrom.
  • the control device 2 is implanted, in particular in the thoracic cage between the skin 4 and the ribs 5.
  • the control device 2 can be implanted as in present-day cardiac pacemakers. However, it is not absolutely essential to implant the control device 2.
  • the control device 2 can also be used in the non-implanted state, that is, as an external device for controlling the electrode device 3.
  • the electrode device 3 can also be used independently of the control device 2.
  • the electrode device 3 can be supplied with energy and/or controlled by another de- vice, optionally even by a nuclear spin tomograph or the like, with suitable matching.
  • the electrode device 3 is preferably implanted in the heart 6 or the heart muscle of the patient, who is shown only schematically and in part.
  • the electrode device 3 can be implanted, for example, as described in US 5,41 1 ,535 A.
  • FIG. 2 is a schematic sectional view of the control device 2.
  • the control device 2 comprises a coil 7 for generating a magnetic field H, a control 8 and preferably an energy storage device 9 such as a rechargeable battery.
  • the coil 7 can optionally be provided with a ferromagnetic, soft-magnetic or ultrasoft magnetic core or a half-sided cladding or another shoe or conducting element to concentrate the magnetic flux.
  • the control device 2 or control 8 can preferably receive or take up the required heart information via means not shown and/or via the coil 7 so that the generation of electrical impulses by the electrode device 3 to stimulate the heart 6 can be controlled in the desired manner.
  • the electrode device 3 to stimulate the heart 6 can be controlled in the desired manner.
  • electrodes, not shown, can also be connected directly to the control device 2, in particular to detect ECG signals or the like.
  • control device 2 or its energy storage device 9 can be inductively recharged in the implanted state.
  • the coil 7 provides a way to generate the magnetic field H, and is preferably used for the inductive charging.
  • another induction device not shown can also be used for charging.
  • FIG. 3 shows the proposed electrode device 3 in a schematic sectional view.
  • the electrode device 3 in particular can be constructed only of passive structural elements and/or without an energy storage device such as a battery. Nevertheless, in a preferred alternative, the electrode device 3 comprises an energy buffer, preferably for storing energy received in wireless manner, in particular a capacitor.
  • the electrode device preferably comprises a coil device 10, an optional pulse forming device 1 1 and preferably at least one electrode
  • the components and electrodes 12 are preferably integrated in the electrically insulated housing 13 or attached thereon.
  • the electrode device 3 is very compact and in particular is configured as substantially rod-shaped or cylindrical .
  • the length is 10 to 20 mm, in particular substantially 15 mm or less.
  • the diameter is preferably at most 5 mm, in particular substantially 4 mm or less.
  • a retaining device can be attached to the electrode device 3, preferably an anchor or a screw which allows the electrode device 3 to be anchored in the heart muscle.
  • the electrode device 3 is configured to generate electrical impulses for the desired stimulation or signal generation.
  • the electrical impulses are delivered, for example, via the electrodes 12.
  • the electrodes 12 are located on opposite sides. However, the electrodes 12 can also be arranged concentrically or otherwise, for example, at one end or at the opposite ends of the electrode device 3 or the housing 13.
  • FIG. 4 shows a schematic block diagram of the electrode device 3 according to the described and preferred exemplary embodiment.
  • the pulse forming device 1 1 preferably comprises an energy buffer, in particular in the form of a capacitor 14, and a resistance 15. Additionally or alternatively, an inductance not shown, such as a coil can also be used for pulse forming.
  • the pulse forming device 1 1 is used for forming or reforming a pulse-like induction voltage which is generated or delivered under certain circumstances, as will be described in further detail hereinafter, by the induction or coil device 10. The reformed electrical impulse can then be output directly for stimulation via the connected electrodes 12.
  • the electrode device 3 preferably comprises a rectifier for rectifying energy received by the coil device 10, a delay means for generating a delay between reception of the energy and generation of the electrical impulse, and/or a protection means to prevent or block generation or delivery of electrical impulses when delivery is not intended. Furthermore, the electrode device 3 can also be implemented by other structural elements having a corresponding function.
  • the induction or coil device 10 is preferably configured such that a pulse-like induction voltage is generated when a minimum field strength of the, i.e., external magnetic field acting on the electrode device 3 or coil device 10 is exceeded.
  • the coil device 10 particularly preferably has a coil core 16 which exhibits an abrupt change in the magnetization, i.e.
  • the coil core 16 is preferably constructed of at least one core element 18, preferably of a plurality of core elements 18.
  • the core elements 18 preferably run parallel to one another so that the coil core 16 has a bundle-like structure of the core elements 18. If necessary, however, only a single core element 18 can be used to form the coil core 16, especially if the energy of the electrical impulse to be generated is relatively low or a different arrangement, for example, comprising a plurality of coil devices 10 is used.
  • Figure 5 shows a preferred exemplary embodiment of the core element 18 in a sectional schematic view.
  • the core element 18 is preferably configured as wirelike.
  • the electrode device 3 for generating electrical impulses is preferably supplied with energy and/or controlled by means of a magnetic field H which can be generated in particular by the control device 2 in an exclusively wireless manner.
  • the electrode device 3 requires no energy storage device such as a battery which restricts the lifetime of usability of the electrode device 3.
  • the electrode device 3 may comprise an energy buffer such as a capacitor for short term storage of energy, preferably transferred in a wireless manner.
  • Such a energy buffer may be adapted for storing energy for five electrical impulses or less, in particular for one electrical impulse only.
  • further energy storing devices as capacitors or inductors may be used for filtering pur- poses, pulse forming or the like.
  • the electrode device 3 is configured such that an electrical impulse is only generated and delivered when a (first) minimum field strength of the magnetic field is exceeded. Furthermore, this or another pulse generation or triggering is pref- erably only made possible after respective previous activation.
  • the impulse generation and triggering preferably takes place as a result of the external magnetic field H acting on the coil device being varied in time so that when the first minimum magnetic field strength H I is exceeded, an abrupt change in the magnetization of the core elements 18 or the coil 16 takes as shown in the schematic magnetization curve according to Fig. 6.
  • this abrupt change in the magnetization results in a pulse-shaped induction voltage (pulse P in Fig. 7) in the allocated coil 1 1.
  • This first minimum field strength H I is therefore a switching threshold.
  • a delay means in particular a reed relay, and/or a protection means may be activated or controlled by the first minimum magnetic field strength H 1 .
  • the induced voltage pulses P can have an amplitude of up to about 5 V and are about 5 to 100 //s long.
  • the optional pulse forming device 1 1 is preferably used.
  • the induced voltage pulse P can thus in particular be stretched in time.
  • a longer pulse duration can also be achieved by bundling a plurality of core elements 18 in the coil 17, in particular so that the pulse forming device 1 1 can be completely omitted.
  • Additional core elements 18 can be provided in the coil core 16 to increase the pulse power.
  • a plurality of coil devices 10 can be connected in parallel or in series to increase the pulse power.
  • the coil core 16 can be used in the coil core 16 to achieve the respectively desired magnetic properties of the coil core 16.
  • the magnitude of the minimum field strength H I depends on various factors, in particular the manufacturing conditions of the core elements 18.
  • the minimum field strength H I is preferably between 0.5 and 20 mT, in particular between 1 to 10 mT and is quite particularly preferably about 2 mT.
  • the individual core elements 18 or the coil core 16 having the bistable magnetic properties can be used in various ways.
  • asymmetrical behavior is achieved on running through the magnetization curve or hysteresis.
  • the polarity of the coil core 16 is (completely) reversed by the external magnetic field H having the opposite direction when the second minimum field strength H2 is exceeded, as can be deduced from the magnetization curve in Fig. 6.
  • the external magnetic field H in particular generated by the control device 2, is used both for controlling (triggering) the generation and delivery of an electrical impulse by the electrode device 3 and also for supplying the electrode device 3 with the energy necessary for generating the electrical impulse.
  • the magnetic field H is preferably also used for said activation of the electrode device 3 for the possible generation of the next electrical im- pulse.
  • this can be also be effected in another manner or by another signal .
  • the external magnetic field H preferably runs at least substantially parallel to the longitudinal direction of the coil core 16 or the core elements 18.
  • Figure 7 shows schematically a preferred time profile V I of the external magnetic field H acting on the electrode device 3 and the corresponding time profile V2 of the voltage U induced in the electrode device 3 or its coil 17.
  • the magnetic-field H is preferably generated intermittently and/or as an alternating field.
  • the magnetic field H preferably has a switch-on ratio of less than 0.5, in particular less than 0.25 , particularly preferably substantially 0.1 or less.
  • the field strength of the magnetic field H has a substantially ramp-shaped or sawtooth-shaped time profile, at least during the switch-on times as indicated in Fig. 7.
  • the magnetic field H is alternately generated with an opposite field direction for alternate generation of an electrical impulse and activation of the electrode de- vice 3 before generation of the next electrical impulse.
  • the activation preferably takes place only shortly before generating the next electrical impulse, as indicated in Fig. 7.
  • the frequency of the magnetic field H is preferably only a few Hz, in particular less than 3 Hz and corresponds in particular to the desired frequency of the electrical impulses to be generated.
  • the ramp-shaped increase in the field strength of the magnetic field H is preferably relatively steep in order to achieve only short switch-on times and only a low switch-on ratio. This is advantageous in regard to minimizing the required energy and a defined triggering with few interfering influences.
  • the maximum field strength of the magnetic field H in the region of the electrode device 3 preferably reaches substantially 1 to 20 mT, in particular 2 to 10 mT.
  • a plurality of electrode devices 3 can be used which in particular can be controlled and supplied with energy by a common control device 2.
  • the electrode devices 3 can then be implanted at different locations, for example.
  • different first minimum field strengths H I different coil devices 10 and/or pulse forming devices 1 1 or the like, desired phase shifts, energy differences or the like can then be achieved in the electrical impulses or signals delivered by the individual electrode devices 3.
  • the delay means can be used for synchronizing the electrode device 3.
  • the preferred synchronization of the stimulation of the heart 6 with the heat beat can be achieved, for example, by evaluating the electric voltage induced in the coil 7 of the control device 2 by the movement of the electrode device 3, optionally in conjunction with the ECG voltage which can be de- tected galvanically via the housing of the control device 2 or a relevant electrode.
  • Particular advantages of the invention reside in the possibility that the wireless electrode device 3 can be implanted in more suitable regions for stimulation, in particular, of the heart muscle, than is possible with wire-bound electrodes.
  • a plurality of electrode devices 3 can be implanted at different locations whereby improved stimulation and in particular better cardiac dynamics can be achieved.
  • FIG 8 is a schematic section of a further embodiment of the proposed elec- trode device 3.
  • the coil device 10 can comprise a coil core 16 or core elements 18 made of a soft magnetic material or ultrasoft magnetic material , for example in the form of wires or strips.
  • a material has a very low coactive field strength which corresponds to the minimum field strength H I and in particular is less than 0.1 mT.
  • the saturation field strengths of the material are less than about 0.01 to 3 mT.
  • the coil core 16 consists of non-magnetic or completely or partially of said soft magnetic or ultrasoft magnetic material or a combination of various such magnetic materials.
  • the electrode device 3 or coil device 10 comprises a coil 17 prefera- bly having a high number of turns, in particular at least 1 ,000 turns, particularly preferably 2,000 turns or more.
  • the coil 17 has substantially 3 ,000 turns or more.
  • the coil inside diameter D 10 is preferably 1 to 3 mm
  • the coil outside diameter D20 is preferably 2 to 6 mm
  • the coil length LI is preferably 10 to 30 mm.
  • ferrites or ferromagnetic metal powder materials can be used as core materials or soft magnetic materials.
  • An advantage is that as a result of the poor electrical conductivity, these materials only exhibit low eddy current losses.
  • the proposed electrode device 3 or coil device 10 permits the generation of rela- tively strong electrical impulses, in particular an impulse having a voltage of at least 1 V and a time duration of substantially 0.1 ms or more. This can be achieved in particular by the bobbin-like coil configuration shown and/or by the high number of turns. In particular, this relatively strong and relatively long- lived electrical impulse can also be achieved with the soft magnetic core mate- rial .
  • a magnetic resetting pulse as with the Wiegand wires or the like is not absolutely necessary. However, a combination with the other magnetic materials or structures is possible.
  • the exciting magnetic field H can only increase relatively slowly (typically from 0 to a maximum of, for example, 0.1 to 2 mT in 0.1 to 5 ms).
  • a relatively broad or long-lived impulse having a duration of at least 0.1 ms, in particular of substantially 0.25 to 2 ms, can be generated. This can possibly be attributed to the alternating current properties of the LRC arrangement (or the coil device 10, high inductance and high winding capacity of the coil) and/or to the retroactive effect of the coil current on the core 16.
  • the electrode device 3 described hereinbefore is preferably again combined with the control device 2 already described or another control device 2 and/or is controlled and/or supplied with energy preferably exclusively by means of an external or varying magnetic field H, as already described.
  • Figure 9 shows another embodiment of the proposed electrode device 3. More precisely, this is not an electrode device 3 but a stimulation device 21 since no electrodes 12 are required as in the preceding embodiments. However, the stimulation device 21 can be used instead of the electrode device 3 or for the stimulation system 1 described previously. The reasoning so far relating to the use and insertion of the electrode device 3 therefore fundamentally apply accordingly for the stimulation device 21 .
  • the stimulation device 21 has a magnetisable element 22 which is preferably surrounded by an optional cladding 23. Electrodes 12 or the like as in the electrode device 3 are preferably not required.
  • the element 22 can be magnetized by an external or varying magnetic field H, in particular, the magnetic field H is generated by the control device 2 or in another suitable manner.
  • Variation of the magnetic field H causes a change in the magnetization of the element 22. Accordingly, the magnetic leakage flux of the element 22 in the tissue surrounding the stimulation device 21 in the implanted state, such as the heart 6, varies in time so that an electrical field strength or an electrical stimulation is generated. Consequently, an electrical stimulation or an electrical impulse is generated in the tissue, such as the heart 6, without electrodes 12.
  • the element 22 is preferably ferromagnetic, in particular at least substantially or exclusively made of ferromagnetic material .
  • the element 22 can also be constructed as described with reference to Fig. 5 and/or it can be constructed as a Wiegand wire or the like and/or from a plurality or a bundle of core elements 18.
  • the stimulation device 21 in particular brings about an amplification of the external magnetic field H at the location of the stimulation device 21 , that is at the implanted site. This makes it possible to achieve specific electrical stimulation in the desired area and/or depending on the magnetic field H.
  • Figure 10 shows another embodiment of the proposed stimulation system 1 comprising the control device 2, the electrode device 3 and an external charging device 24 in a schematic diagram similar to a block diagram.
  • a plurality of short magnetic field pulses are generated as a sequence by the control device 2 during the switch-on time of the magnetic field H , i .e. during the switch-on phases.
  • the coil arrangement 10 or its coil core 16 always changes its magnetization far below the saturation state.
  • a minimum energy consumption can be achieved since the largest possible flux variation in the core of the coil arrangement 10 of the electrode device 3 is present or produced during the entire switch-on time of the magnetic field H and therefore substantially during the generation of the electrical impulse.
  • the magnetic field pulses can be unipolar or bipolar when using soft magnetic core materials. Bipolar magnetic field pulses are used when using bistable materials.
  • bipolar magnetic field pulses are preferably generated by means of a bridge of switching transistors Ml to M4 (e.g. MOSFETS, also in complementary design) or other switching semiconductor components.
  • the control 8 can, for example, comprise one or two signal generators V2 and V4.
  • Preferably connected in parallel to the energy storage device 9 is a smoothing capacitor 25.
  • separating electronics 26 such as a switch or the like can be provided.
  • the control device 2 or its coil 7 is preferably configured such that the control device 2 or its energy storage device 9 can be inductively charged in the implanted state, in particular via the coil 7.
  • the charging device 24 is equipped with a suitable coil 27 and a corresponding power supply, in particular an alternating current supply 28.
  • multiple magnetic field pulses are used to control the electrode device 3 and to generate the respectively desired electrical impulses, i .e. multiple magnetic field pulses form one single electric pulse for one stimulation.
  • the electrode device 3 comprises a rectifier (in Fig. 10 formed by the shown diodes or any other components, in particular with a means for smoothing the resulting electrical voltage, here in the form of a capacitance) .
  • a single electrical impulse can be generated as desired, in particular as discussed in the following with regard to Fig. 1 1 .
  • Figure 1 l a) is a schematic diagram showing a possible pulse sequence (voltage over time t) generated by the control 8 and allowing optimum triggering of the bridge.
  • the trigger pulses in this case for the bridge of switching transistors, are preferably only generated during the switch-on time t on to t off , i .e. when the magnetic field H is switched on.
  • the trigger pulses each last less than 50 is.
  • a first pulse 1 shown by the continuous line
  • a certain delay time of, for example, At, of about 1 to 10 / ⁇ s
  • an opposite pulse 2 then follows for the duration t 2 which in particular corresponds to the first duration t, , and which reverse the primary coil voltage (voltage of the coil 7) via the bridge.
  • This alternating generation of trigger pulses is repeated n times until a sufficient number of pulses consisting of positive and negative paired single pulses has been delivered.
  • the trigger pulses or pulse sequences shown results in a sequence of in particular at least substantially sawtooth- shaped, preferably bipolar magnetic field pulses (shown as current through the coil 7 over time t in Fig. 1 1 b) which act on the electrode device 3 or its coil device 10 (secondary coil) as the magnetic field H in the sense of the present invention and there bring about the generation of an electrical impulse (or a sequence of electrical impulses for each single stimulation) for stimulation.
  • Figure 1 1c) shows an electrical impulse (in particular a superposition of partially smoothed individual impulses) generated by the magnetic field pulses or the pulse-like varying magnetic field H as a schematic diagram of voltage over time t.
  • the length of the electrical impulse depends on the length of the switch- on time of the trigger pulses or the magnetic field pulse and substantially corresponds particularly preferably to the switch-on time.
  • energy transmitted via one or more magnetic fields pulses can be buffered using an energy buffer of the electrode device 3.
  • Similar behavior can be achieved with a unipolar sequence of magnetic field pulses.
  • the left part of the bridge and the generator V2 in Fig. 10 as well as the dashed pulse sequence 2 in Fig. 1 1 c) can be omitted.
  • the duration between two trigger pulses At should be selected so that the second pulse is triggered when the primary coil current which initially decreases quasi- linearly towards zero, reaches the zero level . This time interval depends both on the R/L value of the coil 7 and on the R/L value of the secondary circuit, in par- ticular the coil arrangement 10.
  • control device 2 substantially the winding resistance and the inductance of the coil device 10 determine the R/L ratio whilst the resistance of the coil device 10 is determined by the winding resistance and the loading resistance (tissue resistance of the stimulated part of the heart muscle or the like which is present at the electrodes 12) and the inductance is determined by the winding inductance taking into account the preferably ferromagnetic core 16.
  • R designates the electrical resistance in general
  • L designates the inductance.
  • the impulses induced in the coil device 10 at times t or t' have different signs, i.e. a pulse sequence of bipolar pulses is obtained (both in the case of unipolar and bipolar excitation by magnetic field pulses).
  • Unipolar electrical impulses are preferably required and generated for stimulation. These are rectified by a rectifier, in particular a bridge or diode rectifier, in the electrode device 3. Particularly preferably the rectifier comprises semiconductor switches as described in further detail later with regards to Fig. 16 and 17.
  • the rectifier is preferably connected between the connections of the coil device 10 and the electrodes 12, as indicated in Fig. 10. This results in unipolar sequences of electrical impulses with peak values. Between the peak values the voltages can be close to zero.
  • a small energy buffer, in particular smoothing capacitor C2 (of, for example, 1 to 200 nF) connected in parallel to the stimulation electrodes can smooth this pulsating voltage sequence if necessary.
  • the capacitance can be optimally matched to the properties of the entire system.
  • the electrode device 3 is preferably only constructed of passive, in particular, few components such as one or a plurality of diodes, in particular Schottky diodes D2, D5, D8, D9 to form the rectifier and/or the capacitor C2.
  • the diodes may be replaced by semiconductor switches as discussed later.
  • the duration of the respective electrical impulse (a single stimulation) generated by the electrode device 3 depends on the respective switch-on time of the magnetic field H, in particular on the number of trigger pulses generated in a sequence and thus on the number of magnetic field pulses generated by the control device 2. Consequently, the control device 2 controls the generation of the electrical impulse or the electrode device 3 by the magnetic field H directly in the initially specified sense of the present invention.
  • the schematic diagram according to Fig. 1 1 c) shows the influence of the recti- bomb and the R/L ratio of the coil device 10 of the electrode device 3.
  • the coil voltage follows the derivative of the primary coil current dl/dt, which preferably increases or decreases quasi- linearly here as a consequence of the smaller R/L ratio of the primary coil (coil 7) when the polarity of the primary coil voltage is reversed.
  • the induced coil voltage (measured as the voltage at the load resistance of the coil 17 - in particular therefore at the tissue resistance present at the electrodes 12) only increases relatively slowly.
  • the proposed method of using relatively short, closely following, rectified electrical impulses as a result of a sequence of short magnetic field pulses or trigger pulses according to Fig. 1 1 in order to generate an electrical impulse for stimulat- ing a single heart beat or the like offers the possibility of adapting the stimulation pulse duration (the total length of the electrical impulse during a switch-on time of the magnetic field H, substantially the switch-on time t on to t off ) to the needs of a particular patient by suitably adjusting the number n of pulse pairs of the trigger pulses by acting externally on the control 8 equipped with at least one suitable sensor.
  • the stimulation pulse duration the total length of the electrical impulse during a switch-on time of the magnetic field H, substantially the switch-on time t on to t off
  • the control 8 equipped with at least one suitable sensor.
  • other electrical or electrotechnical design solutions are also possible.
  • Fig. 12 shows a B(H) curve (schematic).
  • ⁇ corresponds to the current variation through the primary coil produced by applying a voltage pulse to its leads.
  • Hysteresis effects have been omitted in the drawing since core materials with very small hysteresis are to be preferred to avoid BH-losses.
  • a constant voltage suddenly applied to the primary coil results in a monotoni- cally increasing current through the coil (equ.l ) and hence a proportionally increasing magnetic field at the site of the electrode device 3 the rate governed by the time constant L/R of the coil circuit.
  • the induced voltage in the coil device 10 of the electrode device 3 is pro- portional to the change of the induction dB/dt in the core element 18 which is a function of magnetic field strength, the induced voltage decreases with time during the time the voltage pulse at coil 7 is on. This means a reduction of the efficiency of conversion of the electric power consumed by coil 7 into a voltage occurring at the posts 12 the longer the voltage is applied to coil 7. Therefore, for optimal efficiency, magnetic field strength needs to be kept small which is reached by switching off or reversing the voltage applied to coil 7 by using short pulse duration times.
  • the amplitude and duration of the induced voltage pulse in the coil device 10 is adjusted by choosing a proper pulse voltage applied to coil 7, a suitable pulse duration and frequency.
  • details of the burst pulse sequence are optimized for minimal energy consumption at a desired pacing pulse shape.
  • the energy consumption is given by where U ] is the voltage at the charging capacitor C before firing a pulse burst and U 2 the voltage after firing a pulse burst after the power supply has been disconnected from C.
  • the optimal operation parameters of the pac- ing system have to be determined experimentally. This is performed for a single pacing pulse preferably according to the diagram shown in Fig. 13.
  • the timing sequence of the voltage pulses comprising a burst applied to the coil 7 can be chosen to produce almost arbitrary pacing pulse shapes. For instance, a ramp-like increase of the pacing pulse is obtained with sequentially increased voltage pulse amplitudes.
  • the pacing pulse can be made to change sign for some arbitrary fraction of time.
  • This may be achieved by using a one-way rectifier 29 or diode Dl instead of the bridge rectifier depicted in Fig. 1 1 and attaching / connecting a Zener diode 30 (or other devices exhibiting a breakdown characteristic like four- layer-diodes, thyristors etc.) parallel to the rectifying diode Dl with an adequate Zener voltage larger than that of the normal rectifying diode, as shown in a preferred exemplary embodiment in Fig. 14.
  • the described possibility might be of advantage since the pacing voltage is reported to increase with time when pacing with unipolar pulses. This potentially undesirable effect is largely reduced by employing a bipolar pacing pulse.
  • the possibility to produce arbitrary bipolar pacing pulses persists when the normal diode Dl is omitted, using the forward and breakdown characteristics of the Zener diode.
  • a preferred implantable electrode device 3 is shown.
  • This electrode device 3 can be used for a stimulation system, preferably a cardiac pacemaker.
  • the electrode device 3 can be supplied with energy by means of a varying magnetic field H.
  • the electrode device 3 preferably comprises means for reception of energy from the varying magnetic field H, in particular a coil device 10 or the like.
  • an electrical impulse can be provided by the implantable electrode device 3 via electrodes 12.
  • the electrical impulse can advantageous be provided between two or more electrodes 12 leading to a current flowing trough an object to be stimulated.
  • the electrode device 3 can comprise a rectifier 31 and/or an energy buffer 32, in particular a capacitor, and/or a delay means 33 for generating a delay between reception of energy and the generation of at least one electrical impulse.
  • the electrode device 3 further can comprise a protection means 34 for preventing or blocking generation of electrical impulses, in particular for a time span after a first electrical impulse has been generated.
  • the electrode device 3 may comprise a pulse forming device 1 1 for forming or shaping the electrical impulse to be delivered by the electrode device 3.
  • the electrode device 3 as well as its components will be described in further detail .
  • the coil device 10 can be provided with energy in a wireless manner, in particular by the time-varying magnetic field H.
  • a current is induced in the coil device 10 by the time-varying magnetic field H.
  • the coil device 10 may comprise an antenna and/or is adapted for receiving energy from electromagnetic waves or the like.
  • Energy received by the coil element 10 preferably is transmitted to the rectifier 31 .
  • the rectifier 31 is adapted to transform energy from a time-varying or alternating nature to a substantially continuous one. In particular, an alternating cur- rent or voltage is rectified.
  • a rectifier 31 preferably comprises semiconductor switches 35 to 38 with a control port for commutation instead or additionally. These can be configured to switch already in the area of a zero-crossing, preferably in contrast to diods having a threshold voltage of about 0.4 to 0.8 Volt.
  • the semiconductor switches 35 to 38, in particular MOSFETs or the like, of the rectifier 31 have a threshold voltage of about zero and/or are biased at about threshold, preferably the threshold voltage and/or an biasing offset from threshold is less than ⁇ 200 mV, in particular less than ⁇ 100 mV or ⁇ 50mV.
  • the rectifier 31 with semiconductor switches 35 to 38 can allow for reduced power losses and/or more efficient rectifying.
  • semiconductor switch 36 preferably a n-channel-MOSFET
  • semiconductor switch 37 preferably a p-channel-MOSFET
  • Semiconductor switches 35 and 38 are non-conducting or having a high resistance and/or impedance as long as the potential of node Kl is higher than the potential of node K2.
  • semiconductor switches 35 and 38 are conducting and semiconductor switches 36 and 37 having a high resistance behavior.
  • node K3 preferably is always connected to the one of the nodes of Kl and K2 with the higher potential and node K4 always this connected to the one of the note of Kl and K2 with the lower potential leading to the rectifying behavior.
  • the control ports or steering ports, in particular gates, of the semiconductor switches 35 to 38 can be connected and/or contacted via inductive elements 43 to 46 as shown in Fig. 17.
  • semiconductor switches comprise a capacitive behavior at their control ports that can be compensated for using the inductive elements 43 to 46.
  • Zehner diods 39 to 42 may be used to prevent over-voltage at the control ports of semiconductor switches 35 to 38.
  • the energy can be stored in the energy buffer 32, in particular a capacitor.
  • the energy buffer 32 is adapted for storing the energy needed for five electric impulses or less, in particular for generating only one single electrical impulse.
  • the energy buffer 32 can be very small, in particular much smaller than a storing device as a battery or the like.
  • the electrode device 3 preferably comprises a protection means 33, in particular with a supervisory component 47 and/or a semiconductor switch 48.
  • the semiconductor switch 48 can be controlled by the supervisory component 47.
  • the semiconductor switch 48 preferably connects the rectifier 31 and/or the storing element 32 to at least one of the electrodes 12.
  • the semiconductor switch 48 can be provided in series with at least one of the electrodes 12.
  • the semiconductor switch 48 has a high resistance state for blocking electrical impulse as well as a low resistance state for generating an electrical impulse or for enabling its generation.
  • the supervisory component 47 preferably is a circuit, in particular an integrated circuit, a microcontroller or the like.
  • the supervisory component 47 preferably comprises a timer. For example, energy is transmitted to the electrode device 3 and a first electrical impulse is generated and/or delivered. As long as this first electrical impulse is generated, the semiconductor switch 48 is conducting and/or the supervisory component 47 generates a corresponding signal that leads to a conducting semiconductor switch 48. After delivery of the first electrical impulse, the supervisory component 47 generates a signal controlling the semiconductor switch 48 such that it changes from a low resistance state to a high resis- tance state for blocking generation and/or delivery of further electrical impulses. Preferably, the supervisory components 47 holds this state for particular time span.
  • the supervisory component 47 can change the control signal in order to switch the semiconductor switch 48 into a low resistance state and the next electrical impulse can be generated and/or delivered.
  • the supervisory component 47 can change the control signal in order to switch the semiconductor switch 48 into a low resistance state and the next electrical impulse can be generated and/or delivered.
  • the protection means 34 is adapted to prevent generation and/or to block delivery of electrical impulses for time span greater than 0.5 ms, preferably greater than 1 ms and/or less than 100 ms, preferably less than 20 ms in particular 10 ms or less.
  • supervisory component 47 and/or semiconductor switch 48 can provide or act as a means for generating a delay between reception of the energy and the generating of at least one of the electrical impulses. If energy is received and preferably rectified, the supervisory component 47 may control the semiconductor switch 48 to get into its high resistance state directly. Afterwards, the energy delivered to the electrode device 3 can be stored in the energy buffer 32 for a particular time span. Afterwards, the semiconductor switch 38 can be switched into its low resistance state, in particular by the supervisory component 47, and the electrical impulse can be generated and/or delivered.
  • the protection means 33 alternatively or additionally can provide the functionality of a delay means as well .
  • the supervisory component 47 can be programmed in advanced and/or by signals transmitted by the magnetic field H accordingly.
  • the supervisory component 47 can comprise a decoding means for decoding a signal provided by the time varying magnetic field H. Therefore, the magnetic field H may comprise modulated information that can be demodulated by the supervisory component 47 and can be used for programming and/or controlling the supervisory component 47.
  • the electrode device 3 may comprise a delay means 34, in particular a reed-switch as shown in Fig. 17.
  • This delay means can block generating and/or delivering the electrical impulse until a particular field strength or minimum field strength HI of the magnetic field H is reached.
  • the delay means 34 preferably is placed in series with at least one electrode 12.
  • the time-varying magnetic field H can provide energy to the elec- trode device 3 using field strengths lower than that needed for controlling or triggering the delay means 34.
  • the magnetic field H can reach or exceed the minimum field strength HI .
  • the supervisory component 47 can be supplied by the energy delivered to the electrode device 3 in a wireless manner and, in particular, stored in the energy buffer 31. Therefore, it is preferred to use a supervisory component 47 with a low power consumption, in particular in the nW regime.
  • Fig. 20A to 20C show a typical timing diagrams of the supervisory component 47.
  • VCC can correspond to the rectified voltage delivered by the rectifier 31.
  • the voltage delivered by rectifier 31 is smoothed by energy buffer 32.
  • Fig. 20A shows an example for the rectified voltage and/or for a voltage associated with the energy buffer 32, which in the following will be called process voltage.
  • Fig. 20B and 20C are showing an inverted and an non-inverted reset signal, respectively.
  • the supervisory component 47 is configured such that the reset signal shown in Fig. 20B keeps low although the process voltage exceeds the pinch of voltage V TH leading to an active reset.
  • the non-inverted reset signal has a high level, leading to an active reset, too.
  • the reset for the supervisory component 47 keeps active.
  • the supervisory component 47 can block and/or keep blocking the delivery of an electrical impulse for a particular time span for generating a time delay, preferably by (keep) opening the semiconductor switch 48, and/or the supervisory component 47 can permit generating the electrical impulse, in particular by closing the semiconductor switch 48, and/or the supervisory component 47 can prevent generation of additional electrical im- pulses for a particular time span after a first electrical impulse has been generated by blocking delivery of the electrical impulse, in particular by opening the semiconductor switch 48.
  • a stimulation system 1 for example a cardiac pacemaker, comprising the implantable control device 3 and, preferably, the electrode device 3 comprising a rectifier 32 with semiconductor switches 35 to 38 and/or the delay means 34 and/or a protection means 33 is shown in Fig. 1.
  • the stimulation system can comprise a second electrode device for generating impulses, that can preferably, but does not need to, comprise a rectifier 32 comprising semiconductor switches 35 to 38 and/or the delay means and/or a protection means 33.
  • Using more than one electrode device 3 in a stimulation system 1 can advantageously lead to a better, more efficient and/or adaptive stimulation.
  • different electrode devices 3 in the stimulation system 1 are placed in some distance, in particular in a distance greater than 1 cm, preferably greater than 2 cm and/or less than 20 cm, preferably less than 15 cm. It is particularly preferred that at least one of the electrode devices 3 comprises a delay means 34 for generating a delay between reception of the energy and the generation of at least one of the electrical impulses.
  • different electrode devices 3 can generate electrical impulses with a time lack between a first electrical impulse generated by the first electrode device 3 and a second electrical impulse generated by the second electrode device 3 which preferably comprises the delay means 34 in this example.
  • a common, additive stimulation can be adapted to the natural behavior of an object to be stimulated, e.g.
  • a heart 6 can be stimulated at a first position and, after a short delay, at a second position, preferably according to its typical activation and/or stimulation. Therefore the second electrode device may 3comprise a reed relay as delay means 33 that can block the output and/or generation of the electrical impulse for the particular time span until a minimum field strength HI for triggering is exceeded.
  • a stimulation system with more than two electrode devices 3 it is particularly preferred that all electrode devices 3 or at least one less than the number of electrode devices 3 actually used comprise delay means 34, in particular (micro-) reed relays. Then, different electrode devices 3 can be triggered independently, in particular if, as preferred, I the dif- ferent reed relays of different electrode devices 3 comprising different thresholds, i.e. different minimum magnetic field strengths HI for triggering.
  • the protection means preferably is adapted to prevent generation and/or to block delivery of electrical impulses for time span greater than 0.5 ms, preferably greater than 1.0 ms and/or less than 100 ms, preferably less than 20 ms, in particular 10 ms or less.
  • generation and/or delivery of an electrical impulse can be prevented or blocked during a short time span that has been found to be sufficient for preventing unwanted electrical impulses that may occur due to a disturbance event, and at the same time a generation of a following electrical impulse is not affected.
  • the induction pacemaker technology described can also be used in combination with conventional cardiac pacemaker technology.
  • the use for left- ventricular stimulation within the framework of resynchronization therapy is particularly appropriate.
  • the present invention makes use of energy recovery by the magnetic field.
  • the present invention uses parameters and operations such that core magnetic saturation in the electrode 3 is avoided. This reduces energy consumption sig- nificantly.
  • the pulse shape can be adjusted arbitrary for the most effective stimulation with respect to the pacing pulse height and width by using a programmable sequence of amplitudes, durations and delay times of the individual burst pulse voltages (voltage source 9, our Fig. 10) applied to the primary coil.
  • a programmable sequence of amplitudes, durations and delay times of the individual burst pulse voltages (voltage source 9, our Fig. 10) applied to the primary coil.
  • the importance of choosing an optimal pulse shape has been described in US 5,782,880 A.
  • This very flexible design also provides the possibility to generate bipolar pacing pulses by controlling the di/dt rate and sign of the current sent through the pri- mary coil7 and making use of Zener diodes or other rectifiers with selectable breakthrough voltages.
  • the burst-pulse sequence is optimized with respect to duration, repetition rate and time delay to achieve minimal energy consumption for a given pacing pulse amplitude an duration. If, e.g., the delay times At, or ⁇ 2 are too small, the energy consumption can increase dramatically.
  • Cu cladded Al strand (Litz) wire in the primary coil is preferred and of advantage for significantly reducing the weight of the coil of the electrode device. It also provides -as also does Cu strand wire- a large degree of mechanical flexibility. Due to the skin effect present because of the alternating current sent through coil 7 the effect of the smaller conductivity of the Al as compared that of Cu is reduced but the weight is determined largely by the aluminum. In an ex- periment, the energy consumption using the Co cladded Al Litz wire was close to that of using pure Cu Litz wire with similar dimensions.
  • Metallic soft or ultrasoft magnetic cores might preferably be used for the electrode device and provide a larger saturation magnetization as compared to ferrite. Accordingly, a lower exciting magnetic field will be needed. Due to the transients of the magnetic field pulses eddy current losses occur in the core material. They are essentially reduced by lamination of metallic cores which is preferred.
  • Magnetically soft cores can be achieved in particular by lamination of multiple isolated layers.
  • Magnetically ultra-soft cores can be achieved in particular by using amorphous or nanocrystalline magnetic materials.
  • the control device 2 is preferably in a flexible housing as it should be implanted directly above the heart near the thoracic wall .
  • the control device can be embedded in a silicon cushion, however other soft materials can also be used.
  • a flux concentrator might be used contained within the interior of the inner surface of the preferably soft housing, preferably silicon cushion.
  • a flux concentrator might be used contained within the interior of the inner surface of the preferably soft housing, preferably silicon cushion.
  • Experiments had shown an increase in magnetic field strength at the pacing site when the coil 7 was halfway surrounded by a thin Mumetal cover the collar of which pointing to the pacing site.
  • Other shapes might be used.
  • the power supply should be preferably provided by tailor made, flexible, lithium polymer batteries.
  • other types of power supplies might be used (thermoelectric using body heat, fuel cells, cells using body fluids).
  • the electrode devices 3 comprises a flexible housing and/or means for magnetic field concentration at the inner surface of the housing as described above.
  • stimulation system 1 can be provided, in particular a cardiac pacemaker, comprising an implantable control device 2 and an implantable electrode device 3 for generating electrical impulses, which can be supplied with energy and/or controlled by the control device 2 in an exclusively wireless manner by means of a time-varying magnetic field H, the control device 2 being configured such that the field strength of the magnetic field, at least during switch-on times, has a substantially ramp- HI , H2 or sawtooth-shaped time profile or is bipolar or pulsed.
  • the control device can be configured such that the magnetic field H is generated intermittently and/or wherein the control device is configured such that the mag- netic field H has a switch-on ratio of less than 0.5 , in particular less than 0.25, particularly preferably substantially 0.1 or less.
  • control device 2 can be configured in such a manner that the magnetic field H is alternately generated with an opposite field direction for the alternate generation of an electrical impulse and activating the electrode device 3 before generating the next electrical impulse, in particular wherein the activation takes place shortly before generation of the next electrical impulse.
  • the frequency of the magnetic field can be less than 3 Hz, in particular corresponds to the desired frequency of the electrical impulses to be generated.
  • the stimulation system 1 is configured in such a manner that in the switched-on state the magnetic field H is formed by a plurality of unipolar or bipolar magnetic field pulses and/or that the respective switch-on duration of the magnetic field H controls or determines the length of each electrical impulse of a stimulation generated by the electrode device 3 and/or the magnetic field H is utilized for energy recovery.
  • the control device 2 in particular is configured in such a manner that the field strength of the magnetic field H in the region of the electrode device 3 is substantially 1 to 20 mT, in particular 2 to 10 mT.
  • the control device 2 in the implanted state can be charged inductively from outside.
  • an implantable electrode device 3 for a stimulation system specifically a cardiac pacemaker, for generating electrical impulses
  • the electrode device 3 is configured as a wireless and/or compact structural unit and can be supplied with energy and directly controlled exclusively by means of a varying magnetic field H, the electrode device 3 com- prising only passive components and a rectifier.
  • the electrode device 3 preferably is configured in such a manner that an electrical impulse is only generated when a first minimum field strength H I of the magnetic field H is exceeded, preferably wherein the electrode device is config- ured in such a manner that it generates and delivers an electrical impulse each time the minimum field strength H I is exceeded, preferably only after a respective preceding activation.
  • the electrode device 3 is configured in such a manner that an elec- trical impulse can be generated in each case only following previous activation, in particular by exceeding a second minimum field strength H2 of the magnetic field having the opposite field direction to the field direction for the generation of an electrical impulse, in particular wherein the second minimum field strength H2 is greater than the first minimum field strength H I .
  • the minimum field H2 strength is substantially 0.5 to 20 mT, in particular 1 to 10 mT.
  • the electrode device 3 may comprise a coil device 10 which generates a pulselike induction voltage when a first minimum field strength H I of the magnetic field is exceeded, in particular wherein the coil device 10 has a coil core 16 or a core element 18 having a magnetization which varies abruptly depending on the acting magnetic field strength and/or having an, in particular, wire-like layer arrangement of soft and hard magnetic material.
  • the electrode device 3 comprises a coil device 10, wherein an electrical impulse having a voltage of at least 0.5 V and a time duration of at least 0.05 ms can be generated by the coil device 10 by an external and/or varying magnetic field H having a field strength in the region of the electrode device of at most 10 mT, in particular substantially 2 mT or less and/or wherein the coil device 10 comprises more than 100 turns, at least 1 ,000 turns.
  • the electrode device in particular comprises only a passively operating pulse forming device 1 1 , in particular having an inductance, a capacitance and/or a resistance, and/or that the electrode device 3 is configured as battery-less and/or amplifier-less, and/or that the electrode device 3 comprises a coil device 10 with a magnetic core 19, the core 19 being magnetically soft or ultra-soft.
  • an implantable stimulation device 21 for a stimulation system 1 in particular a cardiac pacemaker, for electrical stimulation can be provided, wherein the stimulation device 21 can be exclusively supplied with energy and in particular controlled by means of an external and/or varying magnetic field H and/or wherein the stimulation device 21 comprises a magnetisable, preferably coil-free element 22 whose magnetization and magnetic leakage flux can be varied by variation of the magnetic field H for indirect, in particular electrode-less electrical stimulation.
  • the element 22 is ferromagnetic or has a magnetization which varies abruptly depending on the acting magnetic field strength.
  • the element 22 comprises an, in particular, wire-like layer arrangement of soft and hard-magnetic material .
  • a method for operating an implantable electrode device 3 for generating electrical impulses can be provided, wherein the electrode device 3 is supplied with energy and directly controlled by means of a magnetic field H to generate the electrical impulses, wherein the magnetic field H in the switched-on state is formed by a plurality of unipolar or bipolar magnetic field pulses and that the respective switch-on time of the magnetic field H controls or determines the length of the electrical impulse respectively gener- ated by the electrode device 3 or during a contiguous sequence of electrical impulses.
  • the number of magnetic field H impulses can be varied for variation of the duration of each electrical impulse or a contiguous sequence of electrical impulses and/or that the magnetic impulses have a substantially sawtooth-shaped profile.
  • the field strength of the magnetic field H can have a substantially ramp- or sawtooth-shaped time profile.
  • the magnetic field H can have a switch-on ratio of less than 0.5, in particular less than 0.25 , particularly preferably substantially 0.1 or less.
  • a method for generating an electrical impulse in tissue, in particular for operating a cardiac pacemaker can be provided, wherein the magnetization of a mag- netisable, preferably ferromagnetic element 22 is varied by an external or vary- ing magnetic field H in order to vary the magnetic leakage flux of the element 22 for direct electrical stimulation or generation of the electrical impulse.
  • a stimulation system 1 in particular a cardiac pacemaker is provided.
  • the stimulation system 1 preferably comprising an implantable control device 2 and an implantable electrode device 3 for generating electrical impulses, which can be supplied with energy and/or controlled by the control device 2 in an exclusively wireless manner by means of a time-varying magnetic field H, at least one of the control device 2 and electrode device 3 comprising a flexible housing.
  • control device 40 37 MOSFET

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  • Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Radiology & Medical Imaging (AREA)
  • Biomedical Technology (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Power Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Magnetic Treatment Devices (AREA)

Abstract

L'invention concerne un dispositif à électrodes implantable, en particulier pour un stimulateur cardiaque, un système de stimulation correspondant et un procédé de commande d'au moins deux dispositifs à électrodes implantables selon l'invention. Une implantation simplifiée, une construction efficace et une commande fiable sont permises parce que le dispositif à électrodes est alimenté en énergie, et de préférence commandé, exclusivement sans fil, via un champ magnétique variable dans le temps. Le champ magnétique est généré par un dispositif de commande de préférence implanté.
PCT/EP2010/004586 2010-07-27 2010-07-27 Dispositif à électrodes implantable, en particulier pour un stimulateur cardiaque WO2012013201A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
PCT/EP2010/004586 WO2012013201A1 (fr) 2010-07-27 2010-07-27 Dispositif à électrodes implantable, en particulier pour un stimulateur cardiaque
PCT/EP2011/003763 WO2012013342A2 (fr) 2010-07-27 2011-07-27 Système de stimulation avec dispositifs à électrodes sans fil synchronisés

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PCT/EP2010/004586 WO2012013201A1 (fr) 2010-07-27 2010-07-27 Dispositif à électrodes implantable, en particulier pour un stimulateur cardiaque

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3290081A1 (fr) * 2016-09-06 2018-03-07 BIOTRONIK SE & Co. KG Stimulateur cardiaque implantable sans contact avec électrode capacitive
WO2019140404A1 (fr) 2018-01-14 2019-07-18 Stimaire, Inc. Stimulateur neuronal sans fil à objet injectable
CN113228464A (zh) * 2018-11-20 2021-08-06 加利福尼亚大学董事会 用于控制无线供电的无引线起搏器的***和方法
WO2023025601A1 (fr) * 2021-08-25 2023-03-02 Walter Mehnert Implant électronique rechargeable
EP4212207A1 (fr) 2022-01-17 2023-07-19 BIOTRONIK SE & Co. KG Dispositif médical implantable pour émettre un signal de stimulation électrique pour effectuer une action thérapeutique
WO2023135054A1 (fr) 2022-01-17 2023-07-20 Biotronik Se & Co. Kg Système de thérapie pour fournir une thérapie cardiaque

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3290081A1 (fr) * 2016-09-06 2018-03-07 BIOTRONIK SE & Co. KG Stimulateur cardiaque implantable sans contact avec électrode capacitive
WO2019140404A1 (fr) 2018-01-14 2019-07-18 Stimaire, Inc. Stimulateur neuronal sans fil à objet injectable
JP2021510575A (ja) * 2018-01-14 2021-04-30 スタイムエアー， インコーポレイテッド 注入可能物を伴う無線神経刺激装置
EP3737458A4 (fr) * 2018-01-14 2021-10-13 Stimaire, Inc. Stimulateur neuronal sans fil à objet injectable
US11504543B2 (en) 2018-01-14 2022-11-22 Stimaire, Inc. Wireless neural stimulator with injectable
JP7382328B2 (ja) 2018-01-14 2023-11-16 スタイムエアー， インコーポレイテッド 注入可能物を伴う無線神経刺激装置
CN113228464A (zh) * 2018-11-20 2021-08-06 加利福尼亚大学董事会 用于控制无线供电的无引线起搏器的***和方法
WO2023025601A1 (fr) * 2021-08-25 2023-03-02 Walter Mehnert Implant électronique rechargeable
EP4212207A1 (fr) 2022-01-17 2023-07-19 BIOTRONIK SE & Co. KG Dispositif médical implantable pour émettre un signal de stimulation électrique pour effectuer une action thérapeutique
WO2023135054A1 (fr) 2022-01-17 2023-07-20 Biotronik Se & Co. Kg Système de thérapie pour fournir une thérapie cardiaque

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