WO2012147061A2 - Défibrillateur et procédé associé - Google Patents

Défibrillateur et procédé associé Download PDF

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Publication number
WO2012147061A2
WO2012147061A2 PCT/IB2012/052127 IB2012052127W WO2012147061A2 WO 2012147061 A2 WO2012147061 A2 WO 2012147061A2 IB 2012052127 W IB2012052127 W IB 2012052127W WO 2012147061 A2 WO2012147061 A2 WO 2012147061A2
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WO
WIPO (PCT)
Prior art keywords
pulse
primary coil
circuitry
coil
implantable
Prior art date
Legal status (The legal status 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 status listed.)
Ceased
Application number
PCT/IB2012/052127
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English (en)
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WO2012147061A3 (fr
Inventor
Janice ANDERSON
Omar Jacinto Escalona
Ganesh MANOHARAN
John Mccune Anderson
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Ulster University
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Ulster University
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Publication of WO2012147061A2 publication Critical patent/WO2012147061A2/fr
Publication of WO2012147061A3 publication Critical patent/WO2012147061A3/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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
    • A61N1/38—Applying electric currents by contact electrodes alternating or intermittent currents for producing shock effects
    • A61N1/39—Heart defibrillators
    • A61N1/3956—Implantable devices for applying electric shocks to the heart, e.g. for cardioversion
    • 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
    • A61N1/38—Applying electric currents by contact electrodes alternating or intermittent currents for producing shock effects
    • A61N1/39—Heart defibrillators
    • A61N1/3975—Power supply
    • 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
    • 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
    • A61N1/38—Applying electric currents by contact electrodes alternating or intermittent currents for producing shock effects
    • A61N1/39—Heart defibrillators
    • A61N1/395—Heart defibrillators for treating atrial fibrillation
    • 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
    • A61N1/38—Applying electric currents by contact electrodes alternating or intermittent currents for producing shock effects
    • A61N1/39—Heart defibrillators
    • A61N1/3968—Constructional arrangements, e.g. casings

Definitions

  • the present invention relates to cardiac defibrillation, and in particular to apparatus and methods for delivering an electrical defibrillation signal to a heart transcutaneously. While the present invention will be described by particular reference to atrial defibrillation, it will be appreciated that the apparatus and methods of the present invention in its various embodiments are equally applicable to ventricular defibrillation.
  • Atrial fibrillation is the most commonly encountered form of cardiac arrhythmia.
  • AF Atrial fibrillation
  • the incidence and prevalence of AF increases with age. AF may have certain consequences including an increased risk of stroke.
  • AF AF pharmacological cardioversion
  • electrical cardioversion pacemaker based therapies
  • atrial ablation techniques Various techniques are used to treat AF, including pharmacological cardioversion, electrical cardioversion, pacemaker based therapies and atrial ablation techniques.
  • Ablation procedures are sti!l under development and require access to skilled practitioners and a specialised catheter lab.
  • Electrical cardioversion may be delivered in a number of different ways. While effective, one drawback of conventional electrical cardioversion is that it typicaily must be delivered under sedation. Automatic atrial defibrillators which automatically detect an episode of AF and deliver a defibrination signal have also been used to treat AF. However, arrhythmia tends to recur frequently when such devices are used, and the administration of such shock-based therapy when the patient is not under sedation may be unpleasant, and can lead to anxiety or depression over time. Another problem with implanted automatic defibrillation devices is that they may have limited longevity, for example due to limited battery life, necessitating periodic surgical intervention. Such devices may also be relatively costly.
  • a cardiac defibrillation apparatus which includes an implanted receiver part and an external transmitter part.
  • the implanted receiver is connected to electrodes implanted in the heart.
  • a RF pulse is transmitted wireless!y from the external transmitter part through the skin to the implanted receiver part via induction between respective coils of the transmitter and receiver parts to cause the receiver to deliver a shock pulse via the electrodes to the heart.
  • An apparatus of this type is described in US 7,1 10,812 B1 , entitled “Cardiac defibrillation".
  • Such devices relying upon transcutaneous energy transfer by induction are advantageous in that they may reduce or eliminate the need for the implanted apparatus to include active components, and hence an internal power supply.
  • transcutaneous defibrillation apparatus have certain limitations.
  • the efficiency of energy transfer from the external transmitter part to the internal receiver part is relatively low.
  • the external part of the apparatus must be relatively heavy and bulky, and the external circuitry relatively complex.
  • the external part typically includes many batteries in order to provide an adequate power level, for example at least ten 12V batteries may be required.
  • known cardiac defibrillation apparatus relying upon transcutaneous energy transfer by induction have not been portable.
  • defibrillation apparatus which operates by transcutaneous energy transfer from an external apparatus to an implanted apparatus, and in particular for an improved externa! transmitter part for such an apparatus.
  • the present invention seeks to provide such an apparatus.
  • an external transmitter apparatus for a cardiac defibrillator apparatus for a cardiac defibrillator apparatus
  • the external transmitter apparatus being operable in use to transmit a radio frequency (RF) pulse which may be received transcutaneously by an implantable receiver apparatus of the cardiac defibrillator apparatus and used by the implantable receiver apparatus to apply a defibri!lating pulse to implantable electrodes connected to the implantable apparatus to enable a defibrillating pulse to be delivered to a heart when the electrodes are implanted in a heart in use;
  • RF radio frequency
  • the external transmitter apparatus comprises a capacitor arrangement, and charging circuitry operable to charge the capacitor arrangement to thereby store energy in the capacitor arrangement,
  • the external transmitter apparatus further comprises a primary coil and circuitry operable to apply a RF pulse to the primary coil to energise the primary coil and cause the primary coil to transmit a RF pulse which may be received by a secondary coil of an implantable receiver apparatus when the primary coil of the external transmitter apparatus is in proximity to a secondary receiver coil of the implantable receiver apparatus in use, wherein the circuitry of the externa! transmitter apparatus is arranged to energise the primary coil for transmitting a RF pulse to the secondary coil using energy stored by the capacitor arrangement.
  • the external apparatus of the present invention forms part of a defibrillation apparatus in which a RF pulse is transmitted wireiessly to an implantable apparatus to enab!e a defibrillating pulse to be applied to the heart.
  • the present invention extends to a cardiac defibrillation apparatus comprising the external transmitter apparatus of the invention in accordance with any of the embodiments of the invention and an implantable receiver apparatus.
  • the implantable receiver apparatus comprises a secondary coil for receiving a RF pulse transmitted transcutaneously by the external transmitter apparatus when the secondary coi! is in proximity to the primary coil of the externa! transmitter apparatus, and circuitry for using the received RF pulse to deliver a defibri!lating pulse to a heart via implantable electrodes connected to the implantable apparatus.
  • a cardiac defibrillator apparatus comprising an external transmitter apparatus and an implantable receiver apparatus,
  • implantable receiver apparatus is arranged to receive a RF pulse
  • the external transmitter apparatus comprises a capacitor arrangement, and charging circuitry operable to charge the capacitor arrangement to thereby store energy in the capacitor arrangement,
  • the external transmitter apparatus further comprising a primary coil and circuitry operable to apply a RF pulse to the primary coil to energise the primary coil and cause the primary coil to transmit a RF pulse which may be received transcutaneously by a secondary coil of the implantable receiver apparatus when the primary coil of the external transmitter apparatus is in proximity to a secondary receiver coi! of an implantable receiver apparatus in use,
  • circuitry of the external transmitter apparatus is arranged to energise the primary coil for transmitting a RF pulse to the secondary coil using energy stored by the capacitor arrangement
  • implantable receiver apparatus further comprises circuitry for using a RF pulse transmitted transcutaneously by the primary coil and received by the secondary coil to deliver a defibrillating pulse to a heart via implantable electrodes connected to the implantable apparatus.
  • the present invention also extends to a kit of parts for the defibrillator apparatus of the invention comprising the external transmitter apparatus and the implantable apparatus.
  • the present invention in accordance with the second aspect may include any or all of the features described in relation to any of the embodiments of the first aspect of the invention to the extent they are not mutually inconsistent therewith, and vice versa.
  • the apparatus of the second aspect may include an external transmitter apparatus in accordance with any of the embodiments described herein, and the apparatus of the first aspect of the invention in any of its embodiments may be used with an implantable receiver apparatus in accordance with any of the embodiments described.
  • the invention in its first aspect relates to the external transmitter part of the defibrillator apparatus, and does not, at least in some embodiments, require the presence of the implantable receiver apparatus.
  • the implantable apparatus is described herein for use in accordance with embodiments in which the implantable apparatus is provided, and in accordance with the second aspect of the invention, this does not imply that the implantable apparatus is an essential feature of the first aspect of the invention.
  • the external transmitter apparatus of the first aspect is arranged to be suitable for use with the implantable apparatus in any of the embodiments described.
  • the apparatus is described as being connected to electrodes for applying a defibrillation pulse to a heart
  • the invention extends to an implantable apparatus providing an output defibrillation signal for application to electrodes implantable in a heart, and extends to an implantable apparatus which is connectable to electrodes implantable to a heart.
  • the energy required for the external transmitter apparatus to transmit a RF pulse for reception by an implanted receiver apparatus for use in providing a defibrillating pulse to the heart is provided by a capacitor arrangement of the external transmitter apparatus.
  • the capacitor arrangement directly provides the power source for energising the primary coil. This enables the size and weight of the external transmitter apparatus to be reduced in comparison to prior art external transmitter apparatus which relied upon large numbers of batteries to power pulse transmission.
  • the capacitor arrangement may be charged to a suitable level for delivering a RF pulse of a given energy level, and may store the energy until the externa! transmitter apparatus is operated to deliver a RF pulse.
  • a power source such as a battery may be used to charge the capacitor which then powers the pulse generation circuitry.
  • the power source does not directly provide energy to the primary coil in contrast to prior art arrangements.
  • the power source may be of a relatively low voltage level, such as a relatively low voltage battery or relatively fewer batteries.
  • the primary coil is arranged to transmit a RF pulse to the secondary coil by induction.
  • the primary coil is an induction transmitting coil
  • the secondary coil is an induction receiving coil
  • the primary coil is arranged to inductively couple to the secondary coil when in proximity thereto for transmitting a RF pulse to the secondary coi!.
  • the primary and secondary coils may be arranged to inductively couple to one another at a resonant frequency as described below.
  • the energy required to deliver a defibri!lating pulse to the heart is provided by the capacitor arrangement, and preferably entirely by the capacitor arrangement.
  • the primary coil is energised for transmitting a RF pulse to the secondary coil using only energy stored by the capacitor arrangement of the external transmitter apparatus.
  • ail of the energy required to induce a RF pulse in the secondary coil of the implantable apparatus is obtained from the charged capacitor arrangement.
  • the energy stored by the capacitor arrangement is used to directiy power the primary coil.
  • energy is transferred from the capacitor arrangement to the implantable apparatus to enable a defibrillating pulse to be delivered to a heart via the implantable electrodes connected to the implantable apparatus when the electrodes are implanted in a heart in use.
  • the energy required to deliver a defibrillating pulse to the electrodes (and hence heart) is obtained solely from the external apparatus, and preferably solely from the capacitor arrangement thereof.
  • the capacitor arrangement is connected to an input of the primary coil or of a circuit e.g. a resonant circuit including the primary coil for supplying energy thereto.
  • the capacitor arrangement of the external transmitter apparatus may include one or more capacitors. Any arrangement may be used to result in a desired level of capacitance.
  • the arrangement may consist of a single capacitor, or an array of two or more capacitors.
  • the array is preferably an array of capacitors connected in parallel.
  • the capacitor arrangement consists of a single capacitor or an array of from two to four, and most preferably two capacitors.
  • the or each capacitor of the capacitor arrangement is an electrolytic capacitor
  • the capacitance of the capacitor arrangement may be selected to minimise the voltage drop experienced over the primary coil during the delivery of a RF pulse.
  • the level of capacitance should therefore be selected by reference to the intended duration and energy level of the pulse that the external apparatus is to deliver, and the voltage or voltages at which the capacitor arrangement is to be charged.
  • the capacitance of the capacitor arrangement is at least 1000pF, or at least 1200 pF, or at least 1500 pF, or at least 1800 pF, or at least 2000 pF. In embodiments the capacitance of the capacitor arrangement is less than 3000 pF, or less than 2500 pF or less than 2200 pF.
  • the external apparatus comprises a power source and the circuitry of the external apparatus comprises an intermediate arrangement to step up the voltage provided by the power source to a given level for charging the capacitor arrangement.
  • the intermediate arrangement is preferably a DC to DC converter.
  • the DC to DC converter is a high voltage DC to DC converter.
  • the intermediate arrangement e.g. DC to DC converter has an input connected to the power source of the external apparatus and an output connected to the capacitor arrangement.
  • the circuitry of the external apparatus is arranged such that the capacitor arrangement e.g. the input thereof is connected to the power source during charging of the capacitor and is not connected to the charging arrangement during RF pu!se delivery.
  • the output of the intermediate arrangement e.g. DC to DC converter is additionally connected to an input of a tuned circuit including the primary coil.
  • the circuitry of the external apparatus is preferably arranged such that the capacitor arrangement is disconnected, preferably automatically, from the charging circuit when fully charged.
  • the power source of the external apparatus is a DC power source.
  • the power source may be a low voltage power source, in embodiments the power source has a voltage of less than 50 V, or less than 25V, or less than 20 V, or less than 15 V, and preferably less than 10V or !ess than 5 V.
  • the power source comprises a battery, most preferably is a single battery, in some embodiments the or each battery is a lithium ion battery.
  • the battery is preferably a rechargeable battery.
  • the charging circuitry of the external apparatus is operable to charge the capacitor arrangement at a voltage of at least 250V, at least 300V, or at least 400V or at least 500V.
  • the charging circuitry may be selectively operable to charge the capacitor arrangement at one or more voltages in a range or ranges of up to a maximum voltage of 50 V or greater, 100V or greater, 150V or greater, 200V or greater, 250V or greater, 300V or greater, or 400V or greater, or 500V or greater. By this it is meant that the maximum charging voltage available is e.g. 50V or greater.
  • the charging circuitry of the external apparatus is selectively operable to charge the capacitor arrangement at one or more voltages In the range of from 20 V to 500 V, or in the range of from 50 V to 500 V, or from 50 V to 350 V, or in the range of from 150V to 300V.
  • the voltage at which the capacitor is charged will define the voltage across the primary coii during RF pulse transmission. Selection of a voltage in these ranges may enable a shock pu!se of up to 160V to be delivered to the heart.
  • the circuitry may be selectively operable to charge the capacitor arrangement at a voltage of less than 100V.
  • the circuitry may be selectively operable to charge the capacitor arrangement at a higher voltage e.g. 250V or greater in some situations, or less than 100V in other situations.
  • the charging circuitry of the external apparatus is operable to charge the capacitor arrangement at a voltage selected from two or more different voltages, and preferably three, four or five or more different voltages.
  • the voltages may lie in any one of the above ranges.
  • the voltage at which the capacitor arrangement is charged will be chosen with regard to the energy level of the RF pulses to be delivered by the external apparatus. Lower voltages may be chosen in some situations to reduce the likelihood of pain being experienced by the patient as a result of the corresponding shock pulse generated, or the need for sedation.
  • the voltage at which the capacitor arrangement is charged may be selectable by a user, it is of course envisaged that the charging circuitry might be operable at only a single charging voltage.
  • the charging circuitry is manually operable to charge the capacitor arrangement.
  • a user may operate a switch or button to initiate charging or recharging.
  • a single touch operation may be used, in other arrangements it is envisaged that the charging circuitry may be controlled by a microprocessor and the circuitry of the external apparatus may comprise a microprocessor for controlling charging of the capacitor
  • charging of the capacitor arrangement may proceed automatically after RF pulse delivery. Charging may be triggered automatically by the microprocessor.
  • the voltage at which the capacitor arrangement is charged may be user selectable in embodiments in which the charging circuitry is controlled automatically or could be controlled automatically.
  • the charging circuitry of the externa! apparatus and the circuitry operable to cause a RF pulse to be transmitted by the primary coil are independently operable.
  • the charging circuitry and the circuitry operable to cause a RF pulse to be transmitted i.e. to apply a RF pulse to the primary circuit for transmission, may be operable to charge the capacitor arrangement or cause a RF pulse to be transmitted respectively in response to user intervention.
  • the apparatus may comprise independently operable user operable controis for each purpose.
  • the controis may be one touch operated controls.
  • the controls may be buttons etc.
  • operation of the charging circuitry may be controlled by a microprocessor as described above.
  • the charging circuitry is arranged such that the capacitor arrangement may be fully charged from an uncharged condition in a time of less than 5 minutes at the or each available charging voltage, and preferably less than 4 minutes, in embodiments the charging circuitry is arranged such that the capacitor arrangement may be fully recharged subsequent to delivery of a RF pulse in a time of less than 45 seconds, or less than 30 seconds, or more preferably less than 20 seconds.
  • the primary coil is an air core coil.
  • the secondary coil is preferably an air core coil.
  • air core coil refers to an induction coil that does not use a magnetic core made of a ferromagnetic material. The term encompasses coifs wound on plastic, ceramic, or other non magnetic forms, as wel! as those having air inside the windings of the coil.
  • air core coils has also been found to be particularly beneficial, as it may result in greater levels of efficiency of transfer of energy from the primary coil to the secondary coil in use.
  • air cored coils used in the prior art
  • Air core coils are small and lightweight in comparison to the conventional ferrite core coils.
  • the air cored coils may also provide greater levels of efficiency of energy transfer than the ferrite cored coils disclosed in the US 7110812 arrangement, and may result in transfer with greater reliability over iarger air gaps and hence skin thicknesses between the primary and secondary coils in use.
  • By increasing the energy transfer efficiency the frequency and energy of the RF pulse applied to the primary coil may be reduced while still resulting in a shock pulse of an energy level suitable for defibrillation being applied to the heart.
  • the use of air core coil also provides a more biocompatible approach.
  • the primary and secondary coils together provide an RF transformer.
  • the primary coil is arranged to provide a resonant coupling to the secondary coil at the operating frequency of the system i.e. at the frequency of the RF pulse applied to the primary coil.
  • the primary coil forms part of a tuned circuit of the transmitter apparatus circuitry.
  • the tuned circuit is tuned to an operating frequency of the system.
  • the tuned circuit is tuned to the frequency of the RF pulse applied to the primary coil.
  • the secondary coil forms part of a tuned circuit of the receiver circuitry.
  • the tuned circuit of the receiver apparatus is tuned to an operating frequency of the system.
  • the tuned circuit is tuned to the frequency of the RF pulse applied to the primary coil.
  • the transmitter and receiver apparatus tuned circuits are tuned to the same frequency.
  • the tuned circuit of the transmitter apparatus and/or the receiver apparatus may be a series or a parallel tuned circuit.
  • the tuned circuits of the transmitter apparatus and the receiver apparatus are both parallel tuned circuits.
  • the or each tuned circuit is preferably an LC tuned circuit.
  • the receiver apparatus may be arranged to carry out some processing e.g. rectification and/or filtering of the RF pulse received by i.e. induced in the secondary coil to obtain a defibri!lating pulse suitable for delivery to a heart via the electrodes.
  • the circuitry of the receiver apparatus is arranged to provide a DC shock pulse for delivery to the heart via the electrodes.
  • the shockmodule may be a rectilinear low tilt pulse.
  • the circuitry of the receiver apparatus comprises rectification circuitry for rectifying RF pulses received by the secondary coil from the primary coil.
  • the circuitry of the receiver apparatus may further comprise filtering circuitry for filtering e.g. smoothing an output of the rectification circuitry.
  • the circuitry of the receiver apparatus comprises a rectification circuit having an input connected to the secondary coil and an output driving the implantable electrodes for delivering defibrillation signals to the heart, optionally via filtering circuitry.
  • the filtering circuitry is arranged to smooth the output of the rectifying circuit.
  • the circuitry of the implantable apparatus includes only passive components.
  • the circuitry of the implantable apparatus includes only the secondary coil, rectification and optionally filtering circuitry.
  • the circuitry of the implantable apparatus may include only small value capacitors required for example to carry out filtering.
  • the circuitry of the implantable apparatus does not include a capacitor of greater than 1 pF capacitance.
  • the secondary coil has a size constrained by the need for the receiver apparatus to be implanted in the body.
  • the secondary coil has an outer diameter of less than 60 mm, and preferably less than 50 mm or less than 40 mm.
  • the secondary coil may be a double layer coil.
  • the primary coil has an outer diameter within the same range as the ranges given for the secondary coil.
  • the primary and secondary coils may be of equal outside diameter.
  • the pulse transmitted by the primary coil of the external transmitter arrangement must be capable of being received transcutaneously by the secondary coil of the implantable receiver arrangement.
  • the apparatus of the present invention may transfer a pulse transcutaneously with greater efficiency than was possible in prior art arrangements, such as that disclosed in US 71 10812.
  • Such apparatus were typically limited to an air gap of no greater than about 15 mm. This makes it possible for a defibrillation pulse to more reliably be induced in the implanted apparatus through the skin, even for patients with relatively greater chest dermal thickness due to adipose tissue.
  • the RF pulse transmitted by the primary coil is receivable by the secondary coil for providing a defibrillation signal via the electrodes when the primary coil and the secondary coil are separated by an air gap of at least 15 mm, or at least 20 mm or at least 25mm.
  • the RF pulse transmitted by the primary coil is receivable by the secondary coil for providing a defibrillation pulse via the electrodes when the primary coil and the secondary coil are separated by an air gap in the range of from 15mm to 30mm.
  • the radio frequency (RF) pulse applied to the primary coil is of an energy level suitable for causing defibrillation of the heart.
  • the RF pulse may then be received by the implantable receiver apparatus and used to apply a defibrillation pulse to a heart via electrodes connected to the receiver apparatus.
  • the frequency of the RF pulse is less than 1 MHz. Using RF in this range enables a smaller and simpler switching arrangement to be used as described below. This may further enhance portability of the external apparatus.
  • the frequency of the RF pulse is less than 0.5 MHz, or less than 0.3 MHz.
  • the frequency of the RF pu!se is in the range of from 100 kHz to 400kHz, or preferably from 200kHz to 300kHz.
  • the circuitry of the external apparatus is arranged to provide an RF pulse of energy less than 5 J, or less than 4J or less than 3J, and preferably in the range of from 0.2J to 5J for transmission to the implantable apparatus.
  • the circuitry of the external apparatus is arranged to provide an RF pulse of energy at least 0.1 J and preferably at least 0.25J for transmission to the implantable apparatus.
  • the pulse transmitted by the external apparatus may be of lower energy in accordance with the invention than was possible with prior art apparatus due to the greater energy efficiency that the apparatus of the present invention provides.
  • the inventors have found that an efficiency of up to 55% can been achieved in some exemplary arrangements.
  • the devices disclosed in US 71 10812 may only have an energy transfer efficiency of around 10% from the primary coil to the secondary coil, with the result that the RF pulse applied to the primary coil must be of greater energy level e.g. at least 5 times greater than with the apparatus of the present invention, to result in a RF pulse of an energy level suitable for defibrillation being generated in the implantable apparatus.
  • the circuitry of the external apparatus is arranged to apply an RF pulse to the primary coil having duration of less than 15 ms.
  • the circuitry of the apparatus is arranged to provide RF pulses having duration of at least 5 ms. In some preferred
  • the duration of the RF pulse is in the range of from 6 ms to 12 ms.
  • the circuitry of the external apparatus is selectively operable e.g. by a user to provide RF pulses having one or more different durations in the above range to the primary coil.
  • the external apparatus is operable to provide a RF pulse having duration of one or both of 6ms and 12 ms duration.
  • the RF pulse applied to the primary coil has a waveform i.e. an envelope waveform that is rectangular or rectilinear low tilt, preferably rectilinear low tilt.
  • the shock pulse delivered to the heart will be monophasic. This may correspond to a simple mode of operation. In other embodiments the shock pulse delivered to the heart may be biphasic. In these embodiments a timed polarity reversal circuit should be incorporated in the implanted apparatus.
  • the circuitry of the external transmitter is arranged such that the capacitor arrangement discharges through the primary coil to energise the primary coil. In this way, the energy stored by the capacitor arrangement is used to energise the primary coii, and will be transferred to the secondary coi! when in proximity to the primary coil.
  • an input of the primary coil or of a tuned circuit including the primary coil is connected to the output of the capacitor arrangement.
  • the capacitor arrangement will provide a DC voltage.
  • the DC voltage is converted to a quasi AC voltage at the RF frequency for energising the primary coil.
  • circuitry of the external transmitter apparatus comprises a switching arrangement drivable at the RF frequency of the RF pulse to be applied to the primary coil to alternately allow and not allow the capacitor arrangement to discharge through the primary coil for energising the coil over a period corresponding to the duration of the pulse to be applied to the coil to thereby apply the RF pulse to the primary coil.
  • the switching arrangement may be such that the capacitor arrangement is connected to earth to allow it to discharge through the primary coil.
  • the frequency of the RF pulse to be applied and the duration of the RF pulse to be applied to the primary coil refer to the desired or intended frequency and duration of the defibrtllating pulse to be applied.
  • the arrangement is driven may be controlled by a keying pulse.
  • the keying pulse will be chosen to have a duration corresponding to the desired duration of the RF pulse to be applied to the coil. That is, the term “keying pulse” refers to an RF pulse enabling time signal. The keying pulse determines the time duration of the RF pulse that is applied to the primary coil.
  • the circuitry of the external apparatus thus comprises a switching arrangement switchable between a first configuration in which the capacitor arrangement may not discharge through the primary coil and a second configuration in which the capacitor arrangement may discharge through the primary coii for energising the coil.
  • the switching arrangement is a high speed switching arrangement.
  • the switching arrangement may comprise an Insulated Gate Bipolar Transistor (!GBT) or OSFET or any other high speed power switching arrangement, in some embodiments the output of the primary coll or of a tuned circuit including the primary coil is connected to the switching arrangement.
  • the circuitry of the externa! apparatus further comprises driver circuitry for driving the switching arrangement at a frequency corresponding to the frequency of the RF pulse to be applied to the primary coil over a keying period corresponding to the duration of the pulse to be applied to the p imary coil to thereby apply the RF pulse to the primary coil.
  • the driver circuitry drives the switching arrangement between the first and second configurations to apply the RF pulse to the primary coil.
  • the driver circuitry is arranged to drive the switching arrangement between the first and second configurations at the RF frequency of the RF pulse to be generated over a period corresponding to the duration of the pulse to be generated.
  • the driver circuitry may comprise an IGBT or MOSFET driver.
  • the driver circuitry may comprise an arrangement for generating an RF pulse for driving the switching arrangement.
  • the driver circuitry may comprise an oscillator for providing a waveform of the RF frequency of the pulse to be applied to the primary coil and an arrangement for generating a keying pulse of the duration of the RF pulse to be applied to the primary coil from the output of the oscillator for driving the switching arrangement. It will be appreciated that some shaping of the RF pulse may be carried out.
  • operation of the external transmitter apparatus to apply the RF pulse to the primary coil for transmission to the implantable apparatus causes the driver arrangement to drive the switching arrangement to thereby initiate application of the RF pulse to the primary coil.
  • operation of the device to cause a RF pulse to be transmitted by the primary coil causes the driver circuitry to generate a pulse of the RF frequency and duration of the pulse to be applied to the primary coil.
  • the circuitry of the external apparatus is operable by a user to cause a RF pulse to be applied to the primary coil.
  • the circuitry may be connectable to the output of an e!ectrocardiagram apparatus (ECG) for providing a trigger signal for initiating shock pulse application in synchronisation with the ECG.
  • ECG e!ectrocardiagram apparatus
  • the primary coil is mounted to a paddle to facilitate placement on a patient's body.
  • the external apparatus is in the form of a portable unit, most preferably a hand held unit.
  • the external apparatus may comprise a housing for the circuitry of the external apparatus, the primary coil being located outside the housing for location on a patient's body and being connected to the circuitry within the housing.
  • the primary coil may be connected thereto by a flexible connector.
  • the components of the external apparatus other than the coil may be provided within a housing.
  • the present invention extends to an apparatus in accordance with the invention in which the implantable receiver apparatus is implanted in a body and the electrodes are implanted in a heart.
  • a single external apparatus could be shared by multiple patients e.g. at an AF treatment centre.
  • the present invention provides an external apparatus for a defibrillation apparatus which may be made more compact and lightweight than could be achieved using prior art arrangements.
  • the present invention extends, in further aspects, to the use of the apparatus of the invention in accordance with any of its aspects or embodiments to deliver cardiac defibrillation.
  • the method comprises the steps of operating the charging circuitry of the external transmitter apparatus to charge the capacitor arrangement, locating the primary coil in proximity to the secondary coil of the implantable apparatus, and causing the circuitry of the external transmitter apparatus to apply a RF pulse to the primary coil to cause the implantable apparatus to deliver a defibrillating shock pulse via the electrodes.
  • the step of causing the charging circuitry to charge the capacitor arrangement is a separate step carried out prior to the step of causing the circuitry to apply a RF pulse to the primary coil.
  • the shock pulse delivery operation may be carried out at a different time or place to the capacitor charging step.
  • One or both of the steps may be initiated in response to a manual operation by a user or may be initiated automatically,
  • the apparatus may be arranged such that one touch operations may be used to initiate one or both of the charging and shock pulse delivery steps.
  • the implantable apparatus is implanted in the body of a patient, and the electrodes implanted in a heart.
  • the method may further include the step of implanting the implantable apparatus in the body of a patient, and may comprise the step of implanting the electrodes in the heart.
  • the apparatus could be used to provide ventricular defibrillation.
  • higher levels of energy would need to be transmitted from the external apparatus to the implantable apparatus e.g. around 20 J.
  • the pulse transmitted from the external transmitter apparatus to the implantable receiver apparatus is an RF pulse.
  • the pulse applied to the primary coil to energise the primary coil is an RF pulse.
  • the RF pulse transmitted by the primary coil and which may be or is received by a secondary receiver coil of an implantable receiver apparatus is an RFinstalle.
  • the term "RF pulse” (“radio frequencytracke”) refers to a burst of alternating current (AC) radio frequency signal.
  • the pulse is typically of a relatively short duration, such as a few milliseconds.
  • the RF pu!se applied in accordance with the invention has a duration of from 6-12 ms.
  • shock pulse The pulse caused by the implantable apparatus to be delivered to a heart via the implantable electrodes is a shock or defibrillating pulse.
  • anoie delivered to a heart will refer to a shock pulse.
  • shock pulse and “defibrillating pulse” are used interchangeably herein.
  • a shock pulse is a shock pulse which is intended to have a defibrillating effect when delivered to a heart.
  • the term "shock pulse” refers to an "ON" state of a DC voltage applied to the heart.
  • the DC voltage will be a high DC voltage.
  • the shock pulse will typically be of relatively short duration. In some exemplary embodiments the duration of the shock pulse in accordance with the invention may be in the range of from 6 ms to 12 ms.
  • the related energy of a shock pulse will be proportional to the square of the voltage level (V 2 ) of the shock pulse and the defibrillating pulse duration. For this reason, the shock pulse may sometimes be referred to as an "energy shock" delivered to a heart.
  • references to a "coil” herein refer to a complete coil assembly including its associated electrical connection terminals.
  • a coil may also be known as an inductor L which may have a particular inductance value (in Henrys H).
  • Windings refers to the wire turns of the coil i.e. to a building element of a coil.
  • Figure 1 is a schematic diagram of an exemplary circuit arrangement of an experimental arrangement of a defibrillator apparatus in accordance with one embodiment of the invention
  • Figure 2 illustrates schematically a system including the defibrillator apparatus in accordance with the invention
  • Figure 3 illustrates the output voltage pulse obtained across a 50 Ohm load in one example arrangement
  • Figure 4 illustrates schematically a prototype system used in a bench test with a 26 mm air gap
  • Figures 4A is a photograph of a typical test set up
  • Figure 4B shows the transmitter board used
  • Figure 4C shows the receiver board used
  • Figure 5 shows a typical IGBT gate signal at approximately 180 kHz switching frequency
  • Figures 6-12 illustrate example waveforms obtained when the capacitor was charged at approx 340 V DC.
  • Figures 13-15 illustrate waveforms obtained when the capacitor was charged to approx 200V DC;
  • FIGS 16-18 illustrate waveforms obtained when the capacitor array was charged to approximately 100V DC
  • Figures 19 and 20 illustrate waveforms obtained when the capacitor was charged to approx 340 V Dc in open and short circuit conditions
  • Figure 21 illustrates schematically a test set up used in bench testing of a prototype system using a body skin model
  • Figure 22 illustrates the test set up showing the skin model
  • Figures 23-31 show output voltage and current waveforms obtained at the 50 Ohm dummy load
  • Figure 32 shows the output ripple on the output voltage and current in more detail
  • Figures 33-35 illustrate the results of open and short circuit tests carried out at the output of the receiver
  • Figure 36 illustrates a test set up used for bench tests using a skin model and a different prototype system
  • Figures 37-45 show the output voltage and current waveforms obtained at the 50 Ohm dummy load
  • Figure 46 shows the output ripple on the output voltage and current in more detail
  • FIGS 47-49 illustrate the results of open and short circuit tests.
  • FIG. 1 is a schematic diagram of an exemplary circuit arrangement of a defibrillator apparatus 1 including an external transmitter part 5 and implantable receiver part 3 in accordance with one embodiment of the invention.
  • the apparatus is a transcutaneous wireless instant power transmission system which may deliver a shock pulse internally into the heart.
  • This Figure illustrates an experimental laboratory arrangement. Rather than being implanted in the body, the implantable apparatus is shown as being arranged such that its secondary coil is separated by an air gap from the primary coil of the transmitter apparatus. In reality, rather than there being an air gap, the skin of the patient would be present in this region separating the coils.
  • the output of the implantable apparatus is shown as being applied over a 50 Ohm load, representative of the resistance of a heart. In practice the output would be applied to electrodes implanted in a heart for applying a shock thereto.
  • the defibrillator apparatus 1 includes an external transmitter part 5, which comprises the components to the left of the air gap 29 in Figure 1 , denoted “outside T x ".
  • the implantable receiver part 3 comprises the components located on the right-hand side of the air gap in Figure 1 , being those parts on the side labelled "implant side R x ".
  • the implantable receiver part 3 may be provided as a single implantable unit.
  • the external transmitter part 5 would be provided as a single unit.
  • the implantable receiver apparatus will be described first.
  • the implantable receiver apparatus 3 includes a secondary coil 30.
  • the secondary coil 30 L s is configured as a double layer of spiral coils L S1 and L S2 .
  • the spiral coils were arranged in parallel, being flat and close to one another, but electrically isolated by a thin non-conductive sheet between the coils.
  • the coils were arranged side by side.
  • the coils are air core coils. Such coils are believed to improve the operating efficiency of the apparatus as well as reducing the size and weight of the coils in comparison to ferrite cored coils.
  • the secondary coii 30 forms part of a resonant circuit with the capacitor 31 C s which is connected in series therewith.
  • the receiver apparatus 3 also includes rectification circuitry 32 for rectifying the voltage induced in the secondary coil 30.
  • the rectification circuitry 32 includes two rectifying diodes D 3 ⁇ 4 and D 2 in a voltage doubler mode with capacitor 31 C s .
  • the receiver apparatus 3 also includes filtering circuitry 34 for filtering the rectified output voltage.
  • the filtering circuitry includes capacitor C F which filters the rectified output voltage V L to extract its DC component.
  • the output of the implantable receiver apparatus 3 would, in reality, be delivered to a heart via electrodes.
  • the output from the receiver circuitry is delivered to a nominal 50 Ohm dummy load 36 which simulates impedance of the heart.
  • the externa! transmitter part of the defibrillator apparatus is designated 5 in Figure 1.
  • the externa! transmitter part 5 is intended to be located external to the body in use.
  • the implantable and external parts are shown to be separated by an air gap 29.
  • the air gap in the example is of 26 mm and simulates a worst case skin thickness scenario in a laboratory setting.
  • the skin of the patient would occupy this space between the primary and secondary coils of the externa! and implanted parts of the apparatus.
  • energy will be transferred transcutaneously between the external and internal parts of the apparatus.
  • the external part of the apparatus includes a power source in the form of a battery 2.
  • the battery has a comparatively low vo!tage as exemplified below.
  • the battery may be a single 4.8 V battery.
  • the battery 2 is connected via a switch 4 S1 to a high voltage DC to DC converter 6.
  • the output of the high voltage DC to DC converter 6 is connected to an energy storing capacitor arrangement C E (8).
  • the capacitor arrangement CE will be referred to as the capacitor C E herein for brevity but may comprise one or more capacitors. It has been found that one or two electrolytic capacitors in parallel providing may be suitable for providing the capacitor arrangement CE.
  • the capacitance C E is, in one example, 2000pF. in practice, other values of the capacitance may be used, but it has been found that a capacitance of at least 1400 pF is advantageous.
  • the output of the capacitor C E is connected to the input of a para!lel LC resonant circuit 10.
  • the resonant circuit includes a capacitor C P (14) connected in parallel with a primary coi! (12) Lp.
  • the primary coil is an air core coil, and is located to facilitate placement on the body of a wearer e.g. by being located on a paddle.
  • the resonant frequency of the resonant circuit 10 is the same as the resonant frequency of the resonant circuit of the implantable apparatus 3.
  • the primary coil 12 is arranged to inductively couple to the secondary coil 30 when excited by an RF signal.
  • the output of the resonant circuit 10 is connected to a high speed switching
  • the switch is movable between a position which enables the capacitor 8 C1 ⁇ 2 to discharge through resonant circuit 10 and primary coil 12 to earth and a position in which the capacitor 8 C E may not discharge therethrough.
  • Driver circuitry is provided for driving the transistor 16 at an RF chopping frequency of the same value as the resonant frequency of the parallel LC circuit.
  • the driver circuitry includes an IGBT driver 18 and a iogic gate 20 for controlling application of an RF chopping signal to the IGBT 16.
  • the RF chopping signal is generated in the following manner.
  • the inputs of the logic gate 20, which is in the form of an AND gate, are connected to the output of an oscillator 22 and a keying unit 24 respectively.
  • the oscillator 22 is arranged to provide an output in the form of an RF signal set at the resonant frequency of the circuit 10.
  • the oscillator 22 is arranged to always be on from the time the apparatus is switched on.
  • the oscillator and the keying unit 24 are powered via V ba u (2).
  • the keying unit 24 is arranged to provide an output in the form of a keying pu!se having a duration corresponding to the duration of a shock pulse to be applied using the defibrillator apparatus.
  • the keying unit was arranged to provide a 12 ms keying pulse for locating the chopping signal provided by the oscillator. Another suitable pulse duration would be 6 ms.
  • An exemplary keying unit 24 is a monostabie pulse generator, implemented with a 555 IC.
  • a RF pulse of the RF signal output by the oscillator 22 will be passed through the Iogic gate 20.
  • the RF pulse is arranged to be of a rectangular or low tilt RF waveform.
  • a pulse of the RF signal will therefore be passed via the IGBT driver 18 to the switching arrangement having a duration corresponding to that of the keying unit pu!se.
  • the output of the oscillator 22 is set to provide an RF signal of less than 1 MHz, and suitably in the range of from 200 kHz to 300 kHz.
  • the RF signal has a frequency of 230 kHz, and the operating resonant frequency of the resonant circuit 10 and the resonant circuit of the implantable apparatus 3 are set to the same value. It has been found that using an RF frequency below 1 MHz enables the switching electronics to be kept to a manageable complexity in size.
  • the keying unit 24 may be commanded by an ECG synchronised trigger as will be described in more detail below.
  • a spiral type of winding (disc-shaped) was used for both the primary coil 12 and the secondary coil 30.
  • the overall secondary coil diameter was set at less than 60 mm to enable the implantable device to be made of a size suitable for implanting in the body.
  • the overall inductance value of the secondary coil L s was set to about 100 ⁇ for operating resonant frequency of about 230 kHz.
  • the inner diameter of each of the coils L S i and l_s2 of the secondary coil 30 was set to 20 mm.
  • the primary coil 12 had the same inner diameter as each of the coils L S i and L S 2.
  • the air gap 29 i.e. distance between the primary and secondary coil discs was set to 26 mm.
  • the implantable apparatus 3 is implanted in the body, and its output connected to electrodes implanted in the heart.
  • the charging circuitry of the external transmitter apparatus 5 is operated to charge the energy storing capacitor C E (8). This may be done at any time, e.g. just before using the apparatus, or following use of the apparatus to deliver a shock pulse to ensure that the apparatus is ready for operation when next required, even if this is not or some time.
  • the step of charging the capacitor may be carried out before or after the external apparatus is located in proximity to the body of a patient.
  • the switch Si (4) is closed to enable the battery 2 to charge the energy storing capacitor C E (8) via the high voltage DC to DC converter 6.
  • the output of the battery passes through the high voltage DC to DC converter 6 stepping up the voltage from the relatively low voltage output of the battery to a voltage of a level desired to be used to charge the capacitor C E (8).
  • the user may be able to select one of a number of voltages to use to charge the energy storing capacitor C E (8) depending upon the energy of a shock pulse to be delivered to a patient.
  • charging may proceed in response to a manual operation by a user to close the switch (4).
  • the user may also manually select the voltage level for the charging process.
  • charging of the capacitor arrangement cou!d alternatively be carried out under the control of a microprocessor.
  • the microprocessor could automatically charge the capacitor CE (8) when it is determined that it is not fully charged, or after delivery of a shock pulse etc.
  • the microprocessor may control the DC to DC converter 6 to result in charging of the capacitor C E (8) at a given voltage level, for example in response to a selection by a user, or in response to an automatic determination of an appropriate energy level for the shock pulse to be delivered, for example based on analysis of an ECG trace for a patient.
  • the primary coil 12 When it is desired to deliver a defibrillating pulse to a patient, the primary coil 12 is located in proximity to the secondary coil 30 of the implanted apparatus 3.
  • the primary coil 12 may be provided on a paddle to facilitate placement. In use, the primary coil 12 will be separated from the secondary coil 30 by the thickness of the skin of the chest surface. This will be iocated in the region designated "air gap 29" in Figure 1.
  • the apparatus In order to initiate application of amodule to the primary coil 2 for transmission to the secondary coil 30, the apparatus is switched on to energise the oscillator 22.
  • the keying unit 24 is controlled to send a keying pulse to the !ogic gate 20 of a duration corresponding to the intended duration of the shock pu!se to be administered via the implantable apparatus 3. This may be 6 milliseconds or 12 milliseconds for example.
  • the keying unit 24 may be caused to provide such a keying pulse in response to a manual action by a user. For example the user may press a button to initiate delivery of a keying pulse via the keying unit, and hence a defibrillation shockinstalle in this way. This may be a single touch operation. In other
  • operation of the keying unit 24 to deliver a keyingmodule may be triggered automatically by the output of an ECG trace from a patient.
  • Activation of the keying unit 24 to deliver a keying pulse causes the logic gate 20 to be switched to an ON state as both of its inputs, from the keying unit 24 and oscillator 22 will be high. This allows the output of the oscillator to be passed through the AND gate. In this way, the oscillator provides an RF frequency signal output at the operating frequency of the system for the same time duration as the keying pulse duration. This is in the range of less than 1 MHz, and may be in the range of from 200 to 300 kHz in preferred arrangements, and in the example described herein is 230 kHz.
  • the logic gate 20 being an AND gate, will allow a signal to pass to the IGBT driver 18 when the output of both the keying unit 24 and the oscillator 22 are high.
  • this arrangement provides a RF pulse of a chopping signal for controlling the switching arrangement 16 with a RF frequency of the output of the oscillator e.g. 230 kHz.
  • the duration of the pulse corresponds to the duration of a pulse provided by the output of the keying unit e.g.
  • This RF pulse of a RF chopping signal causes the IGBT 16 to move between a position in which the capacitor C E 8 may discharge through the resonant circuit 10 and hence over the coil 12 and in which it is prevented from discharging therethrough at the frequency of the RF chopping signal e.g. 230 kHz over the duration of the pulse.
  • a pulse of quasi AC type voltage is applied to the primary coil 12 thereby energizing the coii at the resonant frequency of the resonant circuit 10.
  • the voltage over the primary coii 12 corresponds to the voltage to which the capacitor C E 8 was charged.
  • the electromagnetic field induced in the primary coil 12 by the RF pulse applied thereto induces a voltage in the secondary coil 30.
  • the induced voltage is rectified by rectification circuitry 32 and filtered by the capacitor C F (34) to produce an output pulse for application to the heart as illustrated in Figure 1.
  • the output pulse is delivered to the nominal 50 Ohm dummy load simulating the impedance of a heart.
  • the RF waveform applied to the primary coil 12 advantageously is a rectilinear low tilt waveform to result in a shock pulse of a rectilinear low tilt shape.
  • the high voltage DC to DC converter 6 is operable to convert the voltage of the battery 2 to aschage for charging the capacitor at up to 400 volts.
  • the charging voltage may be selectable to be at one or more different given voltages within this range.
  • the charging voltage may be selected to be any one of a number of steps in the range of up to 400 volts, such as 25 volts, 50 volts, 70 volts, 100 volts, 150 volts, 200 volts, 250 volts, 300 volts, 350 volts and 400 volts.
  • the apparatus may be arranged such that initial charging of the capacitor C E (8) takes up to 3 minutes.
  • the apparatus should be arranged such that subsequent recharging of the capacitor C E takes no more than 15 seconds after delivery of a shock pulse,
  • the energy stored in the energy storing capacitor arrangement C E (8) is used to deliver the DC shock pulse to the heart via the implanted apparatus.
  • the energy stored in the capacitor arrangement C E is used to energise the primary coil 12. Energy is then transferred subcutaneously to the secondary coil 30.
  • the size of the external transmitter apparatus 5 may be reduced, allowing a more compact and lighter weight apparatus to be provided.
  • the external transmitter apparatus may be provided as a portable, hand-held unit. It will be seen that the implantable apparatus 3 includes only passive components. All of the power requirements for applying a defibrillator shock pulse are supplied by the external transmitter apparatus 5, specifically by the energy storing capacitor C E (8). This enables the complexity and size of the implantable apparatus to be reduced.
  • the external transmitter components may be provided as a unit which will include all of the components shown in Figure 1 , and will include oscillator 22 and keying unit 24.
  • the primary coil will be provided on a paddle connected to the main circuit of the external unit.
  • the system includes a radio frequency externa! transmitter apparatus (100) denoted "RFT” standing for Radio Frequency Transmitter, This corresponds to the external part 5 of the apparatus shown in Figure 1.
  • RFT radio frequency externa! transmitter apparatus
  • this transmitter apparatus 100 is in communication transcutaneously through a skin barrier 101 with an implanted part of the apparatus 102, labelled "PIAD”. This stands for "passive implantable atrial defibrillator”.
  • PIAD implanted part of the apparatus 102
  • the implanted part of the apparatus 102 is connected via defibrillation leads 104 including a right atria! lead (RA) and a coronary sinus !ead (CS) to the heart 106 to enable an output shock pulse provided by the implanted part 102 to be delivered to the heart.
  • defibrillation leads 104 including a right atria! lead (RA) and a coronary sinus !ead (CS) to the heart 106 to enable an output shock pulse provided by the implanted part 102 to be delivered to the heart.
  • RA right atria! lead
  • CS coronary sinus !ead
  • the system also includes an ECG monitor 108 connected to the body surface using standard disposable ECG eiectrodes.
  • An R wave detector 110 is connected to the output of the ECG monitor 108, and an R-R interval/trigger device 1 12 is connected to the output of the R wave detector 1 10.
  • the trigger device 1 12 is operable to cause a RF keying unit 1 14 connected thereto to deliver a keying pulse to initiate a defibrillatingmodule delivery cycle.
  • the keying pulse causes a RF power source 1 16 to energize the oscillator of the external transmitter device to result in a pulse of a radio frequency signal being applied to the primary coil of the external transmitter 100 e.g.
  • the defibrillator apparatus of the present invention does not require any battery or an energy storage device such as a capacitor of high voltage or large value in the implanted device. This is beneficial as such components are bulky, and tend to be expensive and have limited life longevity requiring surgical intervention for their replacement or maintenance,
  • the implanted device part may function with just passive electrical components, such as a pick-up coil, rectifying diodes and small value capacitors of capacitance less than 1 micro farad. This may yield a more robust device with a lower number of electrical components and iower pull of relativity of malfunction. The inherent material manufacturing costs may also be reduced.
  • the external hand-held device which is relatively more complex may be shared among several patients for example at an atrial fibril!ation treatment centre.
  • the defibrillation apparatus is arranged to deiiver rectilinear low tilt defibrination waveforms, which may be more efficacious, in particular at reduced voltage levels such as less than 75 vo!ts, in that pain due to shock delivery has been found to be more tolerable under light sedation or even no sedation.
  • the output pulse at the implanted circuit is also rectilinear low tilt.
  • a spiral type of winding was used for both the primary and secondary coiis (12, 30).
  • the primary and second coils were air cored.
  • the distance between the primary and secondary coil discs (air gap (29, Fig. 1 ) was set to 26 mm.
  • the secondary coil (30) (L s ) was configured as a double layer of spiral coils (L S i and L S2 ) of the same diameter as the primary coil ( 12) (L P ).
  • the inductance value L s of the secondary coil was set to about 100 ⁇ for an operating resonant frequency of about 230 kHz.
  • the primary coil 12 and each of the coiis making up the secondary coil had an inner diameter set to 20 mm.
  • the rectifier circuitry of the implantable apparatus used rectifying diodes (D-, and D 2 ) in a voltage doubler mode with C s (see Fig. 1 ).
  • the rectified output voltage (V L ) was filtered by C F to extract its DC component.
  • the chopping signal (set to about 230 kHz) was logic gated via AND gate (20) by a 12 ms keying pulse from a keying unit (24) commanded by an ECG synchronised trigger.
  • VCEO Voltage at which the primary energy capacitor C E is charged.
  • V LMA Maximum voltage across the 50 ⁇ load (V L ) at the secondary side.
  • _ Voltage drop of V L after 12 ms.
  • % Tilt Percentage of waveform tilt, calculated as (AV L / V Lma x) ⁇ 00
  • AECE Total energy withdrawn from C E during the transmission of energy ( 12ms).
  • ⁇ 50 ⁇ Total energy delivered to the 50 ⁇ load at the secondary side.
  • the proposed circuit configuration of the secondary coil performed well and cou!d provide high V Lma x with a low number of components in the rectifying circuit.
  • Figure 3 illustrates an output voltage pulse of 12 millisecond duration across the 50 ohm load (V L ) for a parameter capacitor (C E ) being charged with a voltage of 267.8 volts.
  • Tests were carried out on a prototype system of the type shown schematically in Figure 4, upon which the test points referred to below are labelled.
  • the system included a transmitter board (200) including the IGBT electronic switch. This was connected to a primary coil (240) of a transformer prototype (270). The primary coil (240) was separated from secondary coil (260) of the transformer by a 26 mm air gap. The secondary coil (260) was connected to a receiver board (280) including rectifier and smoothing circuitry. The output of the receiver board (280) was connected to a dummy load (50 Ohm) to simulate impedance of the heart.
  • the components of the transmitter board 200 correspond to the components of the external transmitter apparatus 3 shown in Figure 1 (excluding the primary coil which is illustrated as part of the transformer prototype).
  • the primary coll L p (12) was located away from the transmitter board, being electrically connected thereto by a pair of wires.
  • the primary coii would be located on a paddie for administering a shock pulse to the chest skin area localised over the subcutaneously implanted receiver apparatus in a patient in use.
  • the capacitor C E was in the form of a capacitor array of capacitance 1360 pF.
  • the power source was a lithium ion battery of voltage 15V.
  • the primary and secondary coils were air cored coils.
  • the components of the receiver board 280 correspond to the components of the implantable receiver apparatus 3 shown in Figure 1 (excluding the secondary coil which is illustrated as part of the transformer prototype).
  • Figure 4A is a photograph of a typical test set up.
  • Figures 4B shows the transmitter board with test point A marked.
  • Figure 4C shows the receiver board with test points B, C and D marked.
  • Tektronix PS280 Laboratory DC Power Supply was used in some tests to power the transmitter board.
  • the transformer prototype was constructed using 0.75mm diameter copper enamel wire.
  • the primary winding consists of one coil with 30 turns.
  • the secondary winding consists of two coi!s, each with 30 turns, connected in a centre-tapped configuration.
  • IRG4PH50PPbF International Rectifier
  • Embedded test code on the transmitter board aflowed the charging capacitor array to be manually charged to the desired value.
  • the final embedded code will allow the charging capacitor array to be charged automatically to the desired value.
  • the user could select another test option to switch the Insulated Gate Bipolar Transistor (!GBT) on/off over a 12 ms gating period.
  • the switching frequency of the iGBT was approximately 180 kHz and this enabled the charging capacitor's DC voltage to be converted to a pseudo AC voltage.
  • This action of converting a DC voltage to an AC voltage allowed the stored energy on the transmitter side to be transformed to the receiver side, i.e. wireless power transmission. In practice, not all the energy will be transferred over the wireless link due to losses in the system, e.g. magnetic coupling losses.
  • Figure 5 shows a typical IGBT gate signal at approximately 180 kHz switching frequency.
  • the charging capacitor array was charged to approximately 340V D c-
  • the IGBT was switched on/off at approximately 180 kHz over a 12 ms period.
  • the following results and waveforms were obtained:
  • Figure 6 shows the output voltage measured across tests points C and D (figure 4), i.e. the 50 ⁇ dummy load.
  • the output voltage is approximately 102V DC with a tilt of 2V DC .
  • Figure 7 shows the Collector-Emitter voltage envelope measured across the IGBT junction in the transmitter board.
  • the peak-to-peak voltage is approximately 1.36 kV.
  • Figure 8 shows the Collector-Emitter voltage measured across the IGBT junction in the transmitter board.
  • the time domain is expanded to show waveform detail (time division:
  • Figure 9 shows the current envelope measured at test point A on the transmitter side of the transformer.
  • the peak-to-peak current is approximately 29, 6A.
  • Figure 10 shows the current envelope measured at test point A on the transmitter side of the transformer.
  • the time domain is expanded to show waveform detail (time division: 5ps/div).
  • Figure 1 1 shows the current envelope measured at test point B on the receiver side of the transformer.
  • the peak-to-peak current is approximately 7.92A
  • Figure 12 shows the output voltage (uppermost darker trace) measured across test points C and D (50 ⁇ dummy load) and the load current (lower lighter traces) measured at test point C.
  • the output voltage is approximately 102V D c and the load current 2.1 A.
  • the charging capacitor array was charged to approximately 200V DC .
  • the IGBT was switched on/off at approximately 180 kHz over a 12 ms period. The following results and waveforms were obtained:
  • Figure 13 shows the output voltage measured across tests points C and D (figure 4), i.e. the 50 ⁇ dummy ioad.
  • the output voltage is approximately 59V D c with a tilt of 2.8V DC .
  • Figure 14 shows the current envelope measured at test point A on the transmitter side of the transformer.
  • the peak-to-peak current is approximately 18.6A.
  • Figure 15 shows the current envelope measured at test point B on the receiver side of the transformer.
  • the peak-to-peak current is approximately 4.6A.
  • the charging capacitor array was charged to approximately 100V DC .
  • the iGBT was switched on/off at approximately 180 kHz over a 12 ms period. The following results and waveforms were obtained:
  • Figure 16 shows the output voltage measured across tests points C and D (figure 4), i.e. the 50 ⁇ dummy load.
  • the output voltage is approximate!y 30.5V D c with a tilt of 1.8V D c-
  • Figure 17 shows the current envelope measured at test point A on the transmitter side of the transformer.
  • the peak-to-peak current is approximately 9.28A.
  • Figure 8 shows the current envelope measured at test point B on the receiver side of the transformer.
  • the peak-to-peak current is approximately 2.52A.
  • the charging capacitor array was charged to approximately 340V DC .
  • the IGBT was switched on/off at approximately 180 kHz over a 12 ms period. The following results and waveforms were obtained:
  • Figure 19 shows the output voltage measured across tests points C and D (figure 4) during a no load condition, i.e. open circuit. It can be seen that the output voltage is limited to 150VDC by the transient voltage suppression (TVS) diode across the output terminals of the receiver, see figure AC.
  • TVS transient voltage suppression
  • Figure 20 shows the current envelope measured at test point C/D during a short circuit condition, i.e. 50 ⁇ load replaced by a piece of wire.
  • the peak-to-peak current is approximately 10.4A.
  • the transmitter was used for the tests with a pulse width set to 12 ms.
  • the primary winding consists of one coil with 30 turns encapsulated with Magic RubberTM.
  • the secondary winding consists of two coiis, each with 30 turns, connected in a centre-tapped configuration.
  • the coils were encapsulated with polyurethane resin.
  • the receiver circuit prototype A, employed four MURS480ET3G rectifiers (RS: 463-51 1 ) and a 1 ⁇ , 250V DC (547-7247) filtering capacitor.
  • the receiver circuit was encapsulated with ER1448 RF epoxy resin.
  • a 50 ⁇ resistive load (10W) was used to simulate the impedance of the heart.
  • the 50 ⁇ resistive load (dummy load) across test points C & D ( Figure 21 ) was removed, i.e. no load condition.
  • the 50 ⁇ dummy load across test points C & D ( Figure 21 ) was replaced by a piece of wire.
  • Figure 22 is a photograph which illustrates the test set up showing the skin model.
  • Figures 23 to 31 show the output voltage and current waveforms obtained at the 50 ⁇ dummy load.
  • Figure 32 shows the output rippie on the outputireage and current in more detail (time division: 2.5ps/div).
  • Figure 33 shows the output current envelope measured at test point C/D (see Figure 21 ) during a short circuit condition, i.e. 50 ⁇ load replaced by a piece of wire.
  • Figures 34 time: 2.5ms/div
  • 35 time: 250ms/div
  • the output voltage is limited to approximately 150V D c (164V peak) by the transient voltage suppression (TVS) diode across the output termina!s of the receiver.
  • Transmitter prototype was as used in the skin model testing described earlier was used for the tests with a pulse width set to 12 ms.
  • Perspex prototype transformer wound with 0.75 mm diameter copper enamel wire around a 20 mm inner core.
  • the primary coi! has one coil with 30 turns.
  • the secondary coil consists of two coils, each with 30 turns, connected in a centre-tapped configuration. The coils were not encapsulated.
  • the receiver circuit employed four MURS480ET3G rectifiers (RS: 463-51 1 ) and a 470nF, 630V DC (547-7253) filtering capacitor. The receiver circuit was not encapsulated.
  • a 50 ⁇ dummy load was used to simulate the impedance of the heart.
  • the 50 ⁇ dummy load across test points C & D ( Figure 21 ) was removed, i.e. no load condition.
  • the 50 ⁇ dummy !oad across test points C & D ( Figure 21 ) was replaced by a piece of wire.
  • Figure 46 shows the output ripp!e on the output voltage and current in more detail (time division: 2.5ps/div).
  • Voltage level switch setting on transmitter prototype 70V.
  • Figure 47 shows the output current envelope measured at test point C/D during a short circuit condition, i.e. 50 ⁇ load replaced by a piece of wire.
  • Figures 48 time: 2.5ms/div
  • 49 time: 250ms/div
  • the output voltage is measured across tests points C and D during a no load condition, i.e. open circuit. It can be seen that the output voltage is limited to approximately 150V DC by the transient voltage suppression (TVS) diode across the output terminals of the receiver.
  • TVS transient voltage suppression

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  • Health & Medical Sciences (AREA)
  • Cardiology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Engineering & Computer Science (AREA)
  • Biomedical Technology (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Radiology & Medical Imaging (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Electrotherapy Devices (AREA)

Abstract

L'invention concerne un appareil et un procédé permettant de délivrer au coeur (36) par voie transcutanée un signal de défibrillation électrique. L'appareil (1) comprend une partie de transmission externe (5) et une partie de réception implantable (3) agencées de manière qu'une impulsion RF (22, 24) peut être transmise par radio à travers une barrière (29) et reçue en interne pour appliquer une impulsion de défibrillation au coeur (36). L'oscillateur (22) et l'unité de saisie au clavier (24) sont alimentés par une source d'alimentation (2). L'émetteur externe (5) comprend un ensemble condensateur (8) connecté à la source d'alimentation (2) et un convertisseur CC-CC de haute tension (6). Le condensateur (8) est connecté via un circuit résonnant (10) à un circuit (16, 18) ayant pour fonction de décharger le condensateur (8) via le circuit résonnant (10) et d'exciter la bobine primaire (12) et d'engendrer la transmission d'impulsions RF. La bobine primaire (12) est couplé par inductance à la bobine secondaire (30) du récepteur implantable (3) pour permettre une transmission radio instantanée de l'impulsion RF à travers la barrière (29). Le récepteur (3) comporte aussi un circuit résonnant, un circuit de rectification (32), et un circuit de filtrage (34).
PCT/IB2012/052127 2011-04-27 2012-04-27 Défibrillateur et procédé associé Ceased WO2012147061A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB1106982.0A GB201106982D0 (en) 2011-04-27 2011-04-27 Defobrillator apparatus and method
GB1106982.0 2011-04-27

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WO2012147061A2 true WO2012147061A2 (fr) 2012-11-01
WO2012147061A3 WO2012147061A3 (fr) 2012-12-27

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WO2019211413A1 (fr) * 2018-05-02 2019-11-07 Kardion Gmbh Système de transmission d'énergie et unité de réception pour la transmission d'énergie sans fil transcutanée
US10946207B2 (en) 2017-05-27 2021-03-16 West Affum Holdings Corp. Defibrillation waveforms for a wearable cardiac defibrillator
CN113713260A (zh) * 2021-07-26 2021-11-30 上海健康医学院 超短脉冲除颤器
US11368081B2 (en) 2018-01-24 2022-06-21 Kardion Gmbh Magnetic coupling element with a magnetic bearing function
US11699551B2 (en) 2020-11-05 2023-07-11 Kardion Gmbh Device for inductive energy transmission in a human body and use of the device
US11752354B2 (en) 2018-05-02 2023-09-12 Kardion Gmbh Transmitter unit comprising a transmission coil and a temperature sensor
US11881721B2 (en) 2018-05-02 2024-01-23 Kardion Gmbh Wireless energy transfer system with fault detection
US11996699B2 (en) 2018-05-02 2024-05-28 Kardion Gmbh Receiving unit, transmission unit, power transmission system and method for wireless power transmission
US12150647B2 (en) 2016-06-06 2024-11-26 Kardion Gmbh Method for punching a lumen and implanting an implant device
US12230868B2 (en) 2018-05-02 2025-02-18 Kardion Gmbh Device for inductive energy transfer into a human body, for example, and use of said device
US12233250B2 (en) 2018-05-02 2025-02-25 Kardion Gmbh Device for inductive energy transmission into a human body and use thereof
US12403296B2 (en) 2018-05-30 2025-09-02 Kardion Gmbh Apparatus for anchoring a ventricular assist system in a blood vessel, operating method, production method for producing an apparatus and ventricular assist system

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Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US12150647B2 (en) 2016-06-06 2024-11-26 Kardion Gmbh Method for punching a lumen and implanting an implant device
US10946207B2 (en) 2017-05-27 2021-03-16 West Affum Holdings Corp. Defibrillation waveforms for a wearable cardiac defibrillator
US11648411B2 (en) 2017-05-27 2023-05-16 West Affum Holdings Dac Defibrillation waveforms for a wearable cardiac defibrillator
US11804767B2 (en) 2018-01-24 2023-10-31 Kardion Gmbh Magnetic coupling element with a magnetic bearing function
US11368081B2 (en) 2018-01-24 2022-06-21 Kardion Gmbh Magnetic coupling element with a magnetic bearing function
US11881721B2 (en) 2018-05-02 2024-01-23 Kardion Gmbh Wireless energy transfer system with fault detection
US11752354B2 (en) 2018-05-02 2023-09-12 Kardion Gmbh Transmitter unit comprising a transmission coil and a temperature sensor
WO2019211413A1 (fr) * 2018-05-02 2019-11-07 Kardion Gmbh Système de transmission d'énergie et unité de réception pour la transmission d'énergie sans fil transcutanée
US11996699B2 (en) 2018-05-02 2024-05-28 Kardion Gmbh Receiving unit, transmission unit, power transmission system and method for wireless power transmission
US12102835B2 (en) 2018-05-02 2024-10-01 Kardion Gmbh Transmission unit comprising a transmission coil and a temperature sensor
US12230868B2 (en) 2018-05-02 2025-02-18 Kardion Gmbh Device for inductive energy transfer into a human body, for example, and use of said device
US12233250B2 (en) 2018-05-02 2025-02-25 Kardion Gmbh Device for inductive energy transmission into a human body and use thereof
US12476488B2 (en) 2018-05-02 2025-11-18 Kardion Gmbh Energy transfer system and reception unit for the wireless transcutaneous transfer of energy
US12403296B2 (en) 2018-05-30 2025-09-02 Kardion Gmbh Apparatus for anchoring a ventricular assist system in a blood vessel, operating method, production method for producing an apparatus and ventricular assist system
US11699551B2 (en) 2020-11-05 2023-07-11 Kardion Gmbh Device for inductive energy transmission in a human body and use of the device
US12400788B2 (en) 2020-11-05 2025-08-26 Kardion Gmbh Device for inductive energy transmission in a human body and use of the device
CN113713260A (zh) * 2021-07-26 2021-11-30 上海健康医学院 超短脉冲除颤器

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