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WO2001089629A1 - Systeme de stimulation des racines sacrales moyennant un implant a alimentation radioelectrique - Google Patents

Systeme de stimulation des racines sacrales moyennant un implant a alimentation radioelectrique Download PDF

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Publication number
WO2001089629A1
WO2001089629A1 PCT/ES2001/000213 ES0100213W WO0189629A1 WO 2001089629 A1 WO2001089629 A1 WO 2001089629A1 ES 0100213 W ES0100213 W ES 0100213W WO 0189629 A1 WO0189629 A1 WO 0189629A1
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WO
WIPO (PCT)
Prior art keywords
implant
stimulation
portable
current
external unit
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/ES2001/000213
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English (en)
Spanish (es)
Inventor
David MARÍN LOZANO
Isaac MARTÍNEZ SABATÉ
Enrique CALDERÓN OLIVERAS
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Villa Sanz Rosa Maria
Consejo Superior de Investigaciones Cientificas CSIC
Original Assignee
Villa Sanz Rosa Maria
Consejo Superior de Investigaciones Cientificas CSIC
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.)
Filing date
Publication date
Application filed by Villa Sanz Rosa Maria, Consejo Superior de Investigaciones Cientificas CSIC filed Critical Villa Sanz Rosa Maria
Priority to AU62357/01A priority Critical patent/AU6235701A/en
Publication of WO2001089629A1 publication Critical patent/WO2001089629A1/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
    • A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
    • A61N1/372—Arrangements in connection with the implantation of stimulators
    • A61N1/37211—Means for communicating with 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
    • A61N1/36007—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation of urogenital or gastrointestinal organs, e.g. for incontinence control
    • 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
    • A61N1/37211—Means for communicating with stimulators
    • A61N1/37235—Aspects of the external programmer
    • A61N1/37247—User interfaces, e.g. input or presentation means

Definitions

  • Sacral root stimulation system by implant fed by radio frequency.
  • Implantable medical product for the control of urination, defecation and erection in patients with neuropathies.
  • the present invention relates to the use of stimulation systems based on implants fed by radio frequency for the control of urination, defecation and erection in patients with neuropathies and, in particular, for spinal cord injuries.
  • the application of electrical impulses to the sacral roots allows patients with neuropathies to control the anal and bladder sphincters. Such stimulation allows emptying of urine from the bladder or its controlled retention. On the other hand, it is also possible to control defecation and in the case of men, erection.
  • the main advantage of controlled stimulation of the sacral roots is the decrease in the necessary currents and their greater dissociation from the sensory fibers whose stimulation is normally associated with pain sensation.
  • the state of the art associated with the present invention focuses on urinary control based on the stimulation of the sacral roots that Brindley developed in the 70s described in patent US3870051.
  • the implantable stimulator generates stimulation pulses in voltage of width and duration related to the radio frequency signal that it receives from an inductive coupling between coils.
  • Each stimulation channel is associated with a coil, the voltage stimulation being dependent on the inductive coupling between the implant coils and the external unit and on the impedance of the electrode-tissue interface itself.
  • the inductive coupling depends on the position and distance between the external coils and the implanted ones, obtaining a non-linear relationship between the programming of the pulses in the external unit and the pulses that are generated in the implant.
  • the position between coils basically depends on how the patient adjusts the external coils with the internal coils that he does not see.
  • the distance depends on the place of the implant and the thickness of the tissue.
  • the object of the invention shares with patent US3870051, the sacral root stimulation technique based on the control of stimulation pulses and stimulation frequencies and the use of implanted electrodes, although not limited to this.
  • the system object of the invention of this patent solves the problems derived from voltage stimulation by generating current stimulation pulses starting from a voltage high enough to guarantee the injection of controlled charge.
  • the generation of the stimulation pulses does not depend on the telemetric link between coils, this being independent of the position and distance between the implanted and external coils.
  • the accuracy and repeatability of the pacing waveforms is ensured by digital programming of the pacing parameters and generation of the pacing pulses in the implant using a 7-bit digital-to-analog (D / A) converter and a crystal controlling the duration of the pulses.
  • the impedance of the electrode-tissue interface can be monitored to determine its variations after implantation and subsequently during the years that the implant must remain in the patient's body. It also incorporates a system to ensure that the energy received in the implant is sufficient for the stimulation requested according to the stimulation parameters that are transmitted from the outside. This system allows the reduction of the power to be transmitted through the skin according to the frequencies and characteristics of the stimulation pulses that are being used. 4. Description of the invention
  • Said system is constituted according to the diagram of figure 1, by two subsystems, one implanted and the other external to the patient.
  • the implanted or implantable system is made up of an implantable stimulator (1) with connection to electrodes (11).
  • the external system is made up of a portable external unit (15) and programming hardware (13) of the portable external unit using specific software (12).
  • the programming software and hardware (12,13) allow the physician to adjust the stimulation and configuration parameters of the portable external unit.
  • the set of stimulation parameters definable by the doctor regarding the stimulation waveforms are at least the following: stimulation frequencies, amplitude of the stimulation current, slope of the stimulus current pulses and duration of the pulses. These parameters are independent between the various stimulation channels of the implantable stimulator (1). Furthermore, it is possible to control time bursts with or without pacing pulses and the maximum time that the patient can use these sequences.
  • the set of stimulation sequences defined by the doctor are associated with different programs which, in turn, are related to the independent control of urination, defecation or erection. Said parameters are sent and stored in the portable external unit (15) by means of non-volatile memory.
  • the portable external unit (15) has the capacity to store the programs defined by the software (12) and transferred from the programming hardware (13) to the portable external unit through the link (14).
  • Said link (14) can be by cable, infrared or wireless data transmission systems.
  • This portable external unit is used by the patient to control his urination, defecation or erection, at his own discretion using the programs and parameters defined by his medical team.
  • the activation and activation of the buttons (17) of the portable external unit supposes the start of the transmission of energy to the implant by inductive coupling between the coils of said unit (18) and the coils (7) of the stimulator implantable (1). The correct alignment between said coils, is notified to the patient by means of light signals or hums coming from the portable external unit.
  • the transmission of the stimulation parameters and the control of the stimulation sequences begins, initiating the stimulation sequence.
  • the patient can end the stimulation sequence using the buttons or moving the portable external unit away from the vicinity of the implantable stimulator.
  • the implantable stimulator (1) is responsible for generating the current stimulation pulses, and the measurements of the electrode-tissue impedance for each of the channels. stimulation and measurement of the induced voltage in the implant coils (7) to ensure that the current stimulation is correct.
  • Most of these electronic circuits are implemented in a specific application integrated circuit that we call with the generic name of ASIC (8). This has the advantage of reducing the area allocated to electronic components as well as consumption and increasing benefits.
  • the system object of the invention has as advantages over other implantable stimulators, the use of step-down type DC DC power converters in a single coil system for receiving energy. This supposes a decrease in the power necessary to achieve, on the one hand, the regulated voltage or voltages necessary for current stimulation circuits and, on the other hand, the regulated voltage for components that do not require a high supply voltage such as the integrated circuit specific application.
  • FIG. 1 It is an overview of the stimulation system object of this patent. Three major blocks are distinguished: 1) The part implanted in the patient consisting of the implantable stimulator (1) and the electrodes (11), 2) the portable external unit (15) and 3) the programming software and hardware (12, 13). - Implantable stimulator (1) - Fabric (3)
  • FIG. 2 It is a block level diagram of the implantable stimulator (1) and the electrodes (11). In this scheme, some of the basic elements for the control of the stimulation are shown (37, 38, 39), the regulation system of the supplies necessary for the operation of the stimulator (29, 30 and 9) and the blocks associated with wireless communication via telemetry for data reception and transmission (7, 33 and 34).
  • Figure 3 Shows the possible implementation of the current output D / A converter (37) based on a stable current source controlled by a stable voltage reference VBG and multiplexing (38) of the output current of the D / A converter he made the output stages of each stimulation channel (II, 12, 13).
  • the control for switching between channels appears in the multiplexer, consisting of the CtrlP switch and the Rp resistance, preventing the appearance of current peaks at the output due to the variation in the impedance that the converter A at each moment has. .
  • Figure 4 Shows the current amplification stage of one of the stimulation channels. This stage amplifies the current coming from the D / A converter in figure 3.
  • a regulated voltage (Vstim) greater than the regulation voltage with which the A / D converter works is used due to the impedance of the electrodes and the electrode interface. tissue, and by the necessary currents of stimulation.
  • the SI and S2 switches are used for the injection of the current to the electrode and for its recovery.
  • the output node Vmeasured refers to the node whose voltage is measured to characterize the electrode-tissue impedance.
  • Figure 5 It is a simplification of the scheme for the impedance meter (40).
  • the stimulation channels are multiplexed to decrease the necessary circuitry, using only a voltage comparator whose supply is that of the amplification stage of Figure 4, and a level displacer connected to the digital control logic (36).
  • FIG. 6 It is a simplified diagram of the implantable stimulator's voltage regulation system (1).
  • the energy receiving coil system (7) is connected to an AC / DC rectifier (29) whose maximum voltage is limited by a voltage limiter (30) connected to a voltage meter (31) that It compares according to a programmable value from the digital control logic (36) and whose objective is to control the power transmission from the portable external unit.
  • the voltage limited by (30) is regulated by a normally linear type regulator
  • Figure 7 Shows the connection between the coil system (7) of the implantable stimulator (1) and the transmitter (33) and receiver (34) included in it, responsible for the transmission and reception of data, respectively, between the implantable stimulator (1) and the portable external unit (15) of figure 1. It goes without saying that the receiver is It is connected to the same coil as the one used in figure 6 for energy reception.
  • a control system of the functions of urination, defecation and erection is described, which we will call control functions, in patients with neuropathies and specifically, for spinal cord injuries.
  • Said system (figure 1) is based on three parts: portable external unit (15), programming software and hardware (12, 13) and implantable stimulator (1) with connection to electrodes (11) through a connector (10).
  • the software (12) is used by the medical equipment for the adjustment of the stimulation parameters and is executed on a hardware (13), this being normally a personal computer.
  • one or more pacing programs defined by one or more pacing sequences are defined for the control functions.
  • the stimulation sequences are characterized by: a) the definition of the stimulation pulses for each of the stimulation channels of the implantable stimulator (1), b) the stimulation frequencies, whether or not they are independent for each stimulation channel and c ) the duration of these sequences.
  • the definition of the pulses is characterized, although not limited, to the definition of the type of current pulse to be applied, containing a monophasic pulse with exponential recovery or a biphasic pulse. Additionally, each stimulation pulse may have one or more controlled current and step slopes associated, forming trapezoidal-looking pulses. For each pulse, the duration and amplitude of the current to be applied are specified.
  • Each pacing channel has an associated pacing rate also definable in the software (12).
  • the stimulation sequences allow specifying durations for each stimulation channel or a set of them, without containing stimulation pulses constituting burst stimulation.
  • the software (12) allows to visualize on a screen associated with the programming hardware (13), the waveforms of the pulses in current and to maintain an associated database to the sequences defined for the control functions for each of the patients using the system object of the invention of this patent.
  • the stimulation control parameters defined by the software (12) are transferred to the outdoor unit (15) via the link (14).
  • Said link allows data transfer from the programming hardware (13) and the portable external unit (15) using a wired, infrared or wireless link by telemetry, or any combination of the mentioned methods.
  • the software (12) allows the medical team to interrogate the implantable stimulator (1) to check the impedance of the interface between the electrodes and the tissue, detecting, when this happens, the total or partial breakage of the electrode or the connector associated with said electrode by large variation of measured impedance. This measure also allows evaluating the evaluation of the electrodes after implantation during the maturation time of the implant and its evolution with implantation time.
  • the interrogation of the electrode impedance measurement is carried out by means of a command transmitted from the programming hardware (13) to the portable external unit (15) through the link (14) and the interrogation from the portable external unit (15) the implantable stimulator (1) by inductive coupling (19).
  • the response from the implantable stimulator follows the opposite path.
  • the external portable unit (15) is the command that the patient uses at will to initiate control functions and which, in turn, is used by the medical team to determine the most appropriate parameters and stimulation sequences.
  • Said unit is of reduced size and light weight powered by one or more batteries (16), these being rechargeable or not as required. In the case of rechargeable batteries, it allows the connection of a battery charger through a conventional connector that makes it impossible to use the external portable unit to control the implantable stimulator (1) during recharging.
  • the external portable unit (15) contains several pushbuttons (17) and switches allowing its ignition and the start of the transfer of energy and information to and from the implantable stimulator (1) by means of the inductive coupling (19) between coil or coils (18 ) of the portable external unit (15) and coil or coils (7) of the implantable stimulator (1), through the skin and tissue that separate the two subsystems. Said inductive coupling is carried out using LC type series or parallel resonant circuits.
  • the portable external unit (15) is normally controlled by a low consumption microprocessor that also manages the writing and reading of non-volatile memory. Said memory stores the information regarding the sequences that must be controlled according to the control functions and statistical information on the use of the implant by the patient.
  • control that the patient has over his control functions does not depend on the programming software or hardware (12 and 13). Additional characteristics of this unit are LEDs indicating the required control functions and the indication by LED or buzzer of a correct positioning of the command (15) with respect to the implantable stimulator (1) guaranteeing sufficient energy in the implant and correct bidirectional communication.
  • the implantable part of the system constitutes the controller for the stimulation of sacral roots.
  • the different stimulation channels of the implantable stimulator (1) are connected to the electrodes by means of a connector or connectors (10), preferably of the pacemaker type, which makes it easier for the medical team in charge of implantation of the implantable stimulator (1).
  • Said stimulator is encapsulated using biocompatible materials, preferably using a ceramic encapsulation allowing the electronic components to be together with the coil system or coils (7) for energy reception and data reception and transmission, reducing the total size of the implant.
  • the coil or coils for the reception of energy in the implantable stimulator must be located in such a way that the possible effect of energy reduction is diminished due to the interference of the magnetic field with titanium in the inductive coupling between the coil system (18) of the portable external unit and the coil system for receiving energy from the implantable stimulator (1).
  • the electronic components of the implantable stimulator are positioned on a printed circuit board or substrate (6).
  • the communication control and control of the stimulation channels are governed by an integrated circuit of specific application, which we call with the generic name of ASIC (8).
  • Said ASIC may contain part or all of the regulation system (9), transmitter and receiver, and stimulation circuit.
  • the implantable stimulator (1) is not limited to the use of specific application circuits or integrated circuits and one or more microcontrollers can be used additionally or as a complement. In any case, it is necessary that the controller be of low consumption to decrease the energy transfer from the portable external unit (15) to the implantable stimulator (1).
  • the main advantages of using an ASIC to control the implant are, in addition to the possible low consumption, the reduction of the total size of the implant.
  • the design of the ASIC using CMOS technologies compatible with bipolar processes (BiCMOS) and DMOS allows a greater integration of the components of the implantable stimulator (1) by allowing higher control voltages in the devices.
  • the maximum currents necessary for stimulation of the sacral roots and the electrode-tissue impedance implies the use of relatively high voltages with respect to the maximum drain-jet voltage of conventional CMOS technologies.
  • the implantable stimulator (1) is characterized, according to figure 2, by a system of coil or coils (7) that constitute typically coil-inductor (LC) resonant circuits that are used for receiving energy and data.
  • the radiofrequency signal generated from the portable external unit through a power amplifier connected to the coil system (18), is received in the coil system (7) of the implant and rectified by a rectifier bridge (29) connected to capacity or capacities. of storage.
  • the bridge rectifier is a full wave rectifier or a voltage bender.
  • a voltage limiter (30) Associated with this voltage at the output of the rectifier bridge (29) we have a voltage limiter (30) that protects the devices, including the associated capacities, from overvoltage.
  • the voltage limiter (30) is characterized by having a behavior similar to a zener and its implementation may vary.
  • the implantable stimulator (1) Due to the control for the reduction of energy transmitted through the skin carried out by the portable external unit (15), the implantable stimulator (1) has a system for measuring the voltage (31) associated with the rectifier bridge. Said system allows comparing with one or several reference levels, notifying by communication from the implantable stimulator (1) to the external portable unit, the result of said comparison.
  • the programming or setting of the comparison levels used in the voltage meter (31) as well as the interrogation of said levels by the external portable unit allows to decrease and control the necessary transmission power according to the operation in each case that has the implantable stimulator and in the distance and alignment situation between coils (7 and 19) that exist.
  • said control allows the patient to know, by means of a buzzer or a led, that the coils have been correctly aligned, being the power received in the implant sufficient for its operation.
  • the implantable stimulator (1) although it may be partially powered by a rechargeable battery, requires the transmission of energy from the portable external unit (15), it has a power-on-reset circuit to ensure its power on.
  • the implementation of said system could be, using a simple RC resistor-capacitor circuit connected to the ASIC reset signal.
  • the circuitry guarantees, although the control logic (36) is not sufficiently powered, voltages that do not exceed the maximum voltages allowed by the devices.
  • the implantable stimulator (1) has a transmitter (33) and receiver (34).
  • the receiver (34) demodulates and decodes the transmitted information, being interpreted by the control logic (36) as commands to control the stimulation, configuration parameters of the implanted system, and requests for information from the implantable stimulator (1).
  • the commands for stimulation control are basically: the start of the generation of the current stimulation pulses for one or more stimulation channels, enabling and disabling channels, definition of the stimulation waveforms and, enabling and disabling of the impedance measurement of the electrode-tissue interface.
  • the configuration commands are mainly intended to control the comparison levels of the voltage meter (31) to control the power delivered to the implant and to fine-tune the stable reference voltage (35) used in analog parts of the ASIC ( 8).
  • the bidirectional communication between the implantable stimulator (1) and the portable external unit (15) is defined synchronously between both systems so that the demodulation and decoding circuits are simplified and avoids or reduces possible interferences between both transmission channels.
  • it is modulated in both cases by modulation in carrier amplitude.
  • the carrier for the transfer of information and data from the external portable unit (15) to the implantable stimulator (1) is of a higher frequency than that used for data transmission from the implantable stimulator. Said system prevents the high power signal transmitted from the portable external unit and / or its harmonics from interfering with the demodulation process of the low power signal transmitted from the implantable stimulator.
  • the voltage regulation system (9) in the implantable stimulator (1) is made up of linear regulators and step-down DC / DC power converters.
  • the regulated voltage for the output stage of the stimulation circuit (90) comes from the output of the rectifier bridge (29) and limited by (30). In this regulation, linear regulators and storage and filtering capacities are used at the output.
  • Control of the voltage at the output of the rectifier bridge (29) by means of the voltage meter (31) and control of the output power of the transmitter of the external portable unit (15) allows the increase in power efficiency of the stimulator regulator (90).
  • the output of the stimulator regulator (90) is associated with one or more step-down type DC / DC power converters (91) to regulate the voltages necessary for the control logic (36) and analog parts of the ASIC (8) or necessary discrete components, and there may be, between said regulated voltages, other regulation systems or level shifters for the control of parts of the implantable stimulator (1).
  • step-down type DC / DC power converters increases the power efficiency of the system due to the difference in voltage between the voltage necessary to generate the current stimulation and the voltage necessary to supply the control logic, this being typically greater than 10 Volts.
  • the generation of the current stimulation pulses is controlled by the control logic (36).
  • Said logic has the information coming from the portable external unit (15) regarding the waveform of the pulses.
  • the pulses in current are controlled by a D / A converter with current output based on a stable current reference dependent on the reference voltage (35).
  • the output current of the D / A converter (37) is multiplexed according to the stimulation channel to be selected by means of an analog multiplexer (38) towards a current amplifier (39) per channel.
  • Said amplifier constitutes the output stage of each channel and is connected to connector (10) by means of decoupling capabilities, avoiding DC voltages at the electrodes.
  • the pacing pulses may contain slopes forming trapezoidal pacing pulses.
  • pulses are generated by steps increasing the output current based on a programmable factor by means of a simple counter implemented in the control logic (36).
  • the recovery of the charge injected through the electrodes is carried out using controlled current or exponential recovery.
  • the resolution of the duration of the pulses and the output current steps is fixed by the clock frequency of the ASIC (8) or a divisor of this. Said clock comes from a crystal connected to the ASIC (8), usually being 1 MHz in frequency.
  • the parameters that define the stimulation pulses are at a minimum: the duration of the pulses, the magnitude of the output current and the existence or not of current steps and their definition. These parameters are independent for each of the stimulation channels.
  • the control of the stimulation frequencies is controlled by the external portable unit (15) reducing the control logic (36).
  • said command specifies more than one channel to stimulate and the architecture of the implantable stimulator is based on a single D / A converter (37), the stimulation pulses are multiplexed in time. In this case, the priority is set by the order (number) associated with the stimulation channels.
  • - External portable unit (15) powered by a single 9V battery in a plastic box containing three buttons (17) associated with each of the three system control functions and two LEDs.
  • the LEDs indicate that the energy transfer is sufficient and that the data transmission is correct.
  • It incorporates a non-volatile memory of EEPROM type for the storage of programs and stimulation sequences.
  • the management of said memory as well as the communication with the programming hardware and the frequency control is implemented in a microprocessor.
  • There is a second microcontroller in charge of generating the data packets to be transmitted and receiving data from the implantable stimulator (1) communicated with the first one and which also manages the indicator LEDs.
  • Step-down type DC DC power converter supplying regulated 5V for the control logic (36) and analog parts of the ASIC (8).
  • the ASIC (8) clock frequency is 1.00 MHz from a crystal and the duration of the stimulation pulses are defined by 8 bits defining stimulation pulses between 4 us and 1024 us with a step of 4 us set by dividing the crystal frequency by four.
  • the stimulation pulses are single phase with exponential load recovery and the duration of the steps in the trapezoidal pulses are calculated based on an increment defined also with 8 bits.
  • the duration of each step is exactly 4 us and the increase in current is the specified one, the duration being limited by the maximum amplitude or by the duration of the stimulation pulse.
  • the independent information for each channel controlled in the ASIC is the existence or not of steps constituting trapezoidal stimulation pulses, the amplitude or increase of the step and the duration of the pulse.
  • the external portable unit controls the stimulation frequencies and the burst times, enabling or disabling the channels by means of a command through the inductive coupling (19).
  • the stimulation frequencies are based on a 32,768 Khz crystal connected to the first of the microcontrollers, setting stimulation frequencies between 1Hz and 120Hz with a step of lHz.
  • the transmission of power from the portable external unit to the implantable stimulator is carried out by means of an E-class power amplifier using a 6 MHz carrier whose maximum supply voltage is controlled according to the required power control and whose minimum supply voltage is 0V modulating the carrier in amplitude with modulation index 100%.
  • the encoding of the pulses is by pulse width.
  • Figure 3 shows the implementation of the D / A converter with current output whose reference current depends on the stable reference voltage (35), called bandgap voltage (VBG).
  • Switches B6 through B0 are the control bits for the output current.
  • the channel multiplexer (38) is implemented using low resistance analog switches (Chl, Ch2 and Ch3).
  • the resistance Rp and CtrlP allow maintaining an impedance equivalent to what the output of the A / D converter will have when one of the Chl, Ch2 or Ch3 channels is activated.
  • the control sequence is to turn on the current reference, apply the control code with B6 .. B0 and activate Ctrlp. Subsequently, it is switched between CtrlP and one of the Chl, Ch2 or Ch3 channels. This reduces current peaks at the output of the D / A converter.
  • the current outputs II, 12 and 13 are connected to three current amplifiers such as those shown in figure 4. Thus, each stimulation channel has an associated 1: n ratio current mirror implemented with bipolars whose multiplication factor of the current is sufficient to supply 40mA.
  • Figure 4 also shows the connection diagram of said stimulation channel to the bipolar connector used.
  • the SI switch is connected when the input current (Channel) is enabled, while S2 remains disconnected. In this situation, the input current is maintained for the duration set by the channel parameters, and may also contain variations in channel due to changes in the B6..B0 code of the D / A converter, generating current steps at the output.
  • load recovery SI goes off and switch S2 short circuits both ends of the electrode.
  • the anodes and cathodes of the electrodes are connected to the connector (10).
  • said channel has the electrode anode connected to the midpoint of switches SI and S2.
  • the cathode is associated with the decoupling capacity.
  • the SI switch connects the regulated supply for the 16V stimulator (Vstim) to the anode.
  • the Vmeasure node is used to measure the impedance according to the diagram in figure 5.
  • FIG 5 it is shown how each channel has its own Vmeasure associated and how these are multiplexed by means of three other switches SI, S2 and S3.
  • the impedance measurement can only be performed on a single stimulation channel at a time.
  • the Soff switch ensures the initial input level to the high voltage comparator (16V).
  • Said comparator compares the selected V measurement with a stable voltage that depends on the stable reference voltage (35) of the ASIC (8).
  • the level adapter converts the comparator output into a CMOS compatible logic level signal.
  • Disabling the impedance measurement supposes the disconnection of SI, S2 and S3 and the activation of Soff, as well as the disabling of the comparator and the level adapter. This mechanism supposes the reduction of the consumption of the ASIC. Since the comparator is in fact a 1-bit converter, the measurement of the impedance is made by programming a sequence of stimuli of different amplitude by sweeping and detecting for which current pulse the comparator has switched its result. Impedance measurements are controlled by software (12) using a personal computer (13) connected to the portable external unit by means of a cable through RS-232C serial communication. The software displays and stores the impedance measurements for each of the three channels.
  • the energy receiver circuit It is based on a 6MHz resonant parallel circuit forming part of the coil system (7) of the implantable stimulator (1).
  • the radio frequency signal coming from the class E power amplifier of the portable external unit, is rectified by means of a full-wave rectifier (29), said rectifier has associated with at least a 47uF / 25V storage capacity whose voltage limiter ( 30) avoid voltages greater than 23-24V.
  • the voltage limiter architecture is based on a bipolar chain acting as zeners and a power NMOS. The resistance has a much higher impedance than that of the equivalent zener when the voltage is higher than the limiting one (around 22 V).
  • a node of the bipolar chain of the power limiter is chosen so that it offers a voltage directly proportional and approximately linear to the rectified voltage in the rectifier bridge and whose voltage is below 5V for the maximum voltage allowed by the limiter.
  • This voltage is used by the voltage meter (31) to compare with a variable and selectable reference voltage between two levels that indicate a voltage at the rectifier bridge output less than 14V or greater than 18V. The result of such comparison is sending to the portable external unit when requested.
  • the indication of a voltage not lower than 14V guarantees that the digital and analog part of the ASIC works and the transmitted parameters have not been lost due to lack of power.
  • the voltage indication above 18V indicates that the implant has enough energy to guarantee the wide range of output currents.
  • the output voltage of the rectifier bridge is the input of the 16V linear regulator. This voltage is used for the current stimulator output stage (Vstim). From the Vstim node we connect a step-down type DC / DC power converter whose output feeds the non-power parts in the ASIC.
  • a scheme for the control of reception and transmission of data in the implantable stimulator is shown in Figure 7.
  • the coil associated with the reception of data is the same as that used for the reception of energy.
  • the ASIC incorporates a low pass filter to eliminate the 6MHZ carrier transmitted from the portable external unit.
  • Said filter associated with a comparator, outputs a signal of 0-5V voltage levels depending on the existence or not of the carrier, respectively.
  • the suppression of the carrier supposes a change in the output level of the filter and the count is started in the counter- 1.
  • Each one of the counters in figure 7 has as its output level a logical 'Y' during non-activation and a logical level '0' after the end of the count.
  • the implementation of said counters can be either by means of a counter at the ASIC clock frequency, 1MHZ, or by controlled discharges of a certain capacity at constant current and comparator at its output.
  • figure 7 also shows the connection to a second coil of the coil system (7) of the implantable stimulator with which information is transmitted to the portable external unit.
  • a simple class B power amplifier is used as a transmitter.
  • the logic at the transmitter input ensures that the transmitter is turned off during the ASIC power-on-reset time.
  • the CLK signal references the 1MHz clock itself obtained from the crystal associated with the ASIC.
  • the data to be transmitted enables the transmitter for a certain time set by counter-5.
  • Data from the implantable stimulator is coded using Manchester code. Synchronization between the portable external unit and the implantable stimulator allows the microprocessor of the portable external unit to limit the time to wait for a response and to control transmission and reception errors by forwarding the data packets.

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  • Health & Medical Sciences (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)
  • Gastroenterology & Hepatology (AREA)
  • Electrotherapy Devices (AREA)

Abstract

L'invention concerne un système de régulation de la miction, de la défécation et, dans le cas des hommes, également de l'érection, destiné à des personnes atteintes de neuropathies et en particulier à des personnes souffrant de lésions médullaires. Ce système comprend, selon le schéma de la figure (1), deux sous-systèmes, dont l'un est implanté et l'autre est externe au patient. Le système implanté ou implantable est composé d'un stimulateur implantable (1) relié à des électrodes (11). Le système externe est composé d'une unité externe portative (15) comprenant un matériel de programmation (13) qui utilise un logiciel spécifique (12). Le logiciel et le matériel de programmation (12, 13) permettent au médecin de régler les paramètres de stimulation et de configuration de l'unité externe portative.
PCT/ES2001/000213 2000-05-26 2001-05-25 Systeme de stimulation des racines sacrales moyennant un implant a alimentation radioelectrique Ceased WO2001089629A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU62357/01A AU6235701A (en) 2000-05-26 2001-05-25 Sacral root stimulating system by means of a radio-frequency powered implant

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ES200001343A ES2164017B1 (es) 2000-05-26 2000-05-26 Sistema de estimulacion de raices sacras mediante implante alimentado por radio frecuencia.
ESP200001343 2000-05-26

Publications (1)

Publication Number Publication Date
WO2001089629A1 true WO2001089629A1 (fr) 2001-11-29

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PCT/ES2001/000213 Ceased WO2001089629A1 (fr) 2000-05-26 2001-05-25 Systeme de stimulation des racines sacrales moyennant un implant a alimentation radioelectrique

Country Status (3)

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AU (1) AU6235701A (fr)
ES (1) ES2164017B1 (fr)
WO (1) WO2001089629A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016007912A1 (fr) * 2014-07-10 2016-01-14 Perryman Laura Tyler Circuit pour dispositif implantable

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3650276A (en) * 1969-03-26 1972-03-21 Inst Demedicina Si Farmacie Method and apparatus, including a flexible electrode, for the electric neurostimulation of the neurogenic bladder
US3870051A (en) * 1972-04-27 1975-03-11 Nat Res Dev Urinary control
WO1993024176A1 (fr) * 1992-05-23 1993-12-09 Keith Edward Tippey Stimulation electrique pour le traitement de l'incontinence et d'autres troubles neuromusculaires
ES2137946T3 (es) * 1991-03-11 2000-01-01 Univ Case Western Reserve Dispositivo de ayuda a la miccion.
WO2000015293A1 (fr) * 1998-09-16 2000-03-23 Axon Engineering, Inc. Stimulation combinee des racines sacree ventrale et dorsale destinee a reguler la fonction vesicale
WO2000025859A1 (fr) * 1998-10-30 2000-05-11 Aalborg University Methode permettant de reguler l'hyperactivite de la vessie

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3650276A (en) * 1969-03-26 1972-03-21 Inst Demedicina Si Farmacie Method and apparatus, including a flexible electrode, for the electric neurostimulation of the neurogenic bladder
US3870051A (en) * 1972-04-27 1975-03-11 Nat Res Dev Urinary control
ES2137946T3 (es) * 1991-03-11 2000-01-01 Univ Case Western Reserve Dispositivo de ayuda a la miccion.
WO1993024176A1 (fr) * 1992-05-23 1993-12-09 Keith Edward Tippey Stimulation electrique pour le traitement de l'incontinence et d'autres troubles neuromusculaires
WO2000015293A1 (fr) * 1998-09-16 2000-03-23 Axon Engineering, Inc. Stimulation combinee des racines sacree ventrale et dorsale destinee a reguler la fonction vesicale
WO2000025859A1 (fr) * 1998-10-30 2000-05-11 Aalborg University Methode permettant de reguler l'hyperactivite de la vessie

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016007912A1 (fr) * 2014-07-10 2016-01-14 Perryman Laura Tyler Circuit pour dispositif implantable
US9522270B2 (en) 2014-07-10 2016-12-20 Micron Devices, LLC Circuit for an implantable device
US10493279B2 (en) 2014-07-10 2019-12-03 Stimwave Technologies Incorporated Circuit for an implantable device
US11426586B2 (en) 2014-07-10 2022-08-30 Stimwave Technologies Incorporated Circuit for an implantable device
US12296173B2 (en) 2014-07-10 2025-05-13 Curonix Llc Circuit for an implantable device

Also Published As

Publication number Publication date
ES2164017B1 (es) 2004-06-01
ES2164017R (fr) 2002-08-01
ES2164017A2 (es) 2002-02-01
AU6235701A (en) 2001-12-03

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