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WO2025108644A1 - Dispositif médical implantable pour réaliser une stimulation cardiaque - Google Patents

Dispositif médical implantable pour réaliser une stimulation cardiaque Download PDF

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Publication number
WO2025108644A1
WO2025108644A1 PCT/EP2024/079683 EP2024079683W WO2025108644A1 WO 2025108644 A1 WO2025108644 A1 WO 2025108644A1 EP 2024079683 W EP2024079683 W EP 2024079683W WO 2025108644 A1 WO2025108644 A1 WO 2025108644A1
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WO
WIPO (PCT)
Prior art keywords
electrical
signal
electrode
electrode pole
stimulation
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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.)
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PCT/EP2024/079683
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English (en)
Inventor
Thomas Dörr
Frank Becker
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.)
Biotronik SE and Co KG
Original Assignee
Biotronik SE and Co KG
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Publication date
Application filed by Biotronik SE and Co KG filed Critical Biotronik SE and Co KG
Publication of WO2025108644A1 publication Critical patent/WO2025108644A1/fr
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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00—Electrotherapy; Circuits therefor
    • A61N1/18—Applying electric currents by contact electrodes
    • A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
    • A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
    • A61N1/362—Heart stimulators
    • A61N1/365—Heart stimulators controlled by a physiological parameter, e.g. heart potential
    • A61N1/36514—Heart stimulators controlled by a physiological parameter, e.g. heart potential controlled by a physiological quantity other than heart potential, e.g. blood pressure
    • A61N1/36521—Heart stimulators controlled by a physiological parameter, e.g. heart potential controlled by a physiological quantity other than heart potential, e.g. blood pressure the parameter being derived from measurement of an electrical impedance
    • 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
    • A61N1/362—Heart stimulators
    • A61N1/37—Monitoring; Protecting
    • A61N1/371—Capture, i.e. successful stimulation
    • A61N1/3712—Auto-capture, i.e. automatic adjustment of the stimulation threshold
    • 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
    • A61N1/362—Heart stimulators
    • A61N1/37—Monitoring; Protecting
    • A61N1/3706—Pacemaker parameters

Definitions

  • Implantable medical device for performing a cardiac stimulation
  • the present invention relates to an implantable medical device for performing a cardiac stimulation according to the preamble of claim 1 and to a method for operating an implantable medical device for performing a cardiac stimulation.
  • An implantable medical device of this kind comprises a generator device comprising processing circuitry for processing electrical signals, an electrode lead connected to the generator device and extending from the generator device, and an electrode pole arrangement comprising at least a first electrode pole and a second electrode pole.
  • the electrode lead comprises a lead body forming a distal end to be arranged on cardiac tissue within a patient’s heart.
  • the processing circuitry is configured to generate an electrical stimulation signal and to provide the electrical stimulation signal to said electrode pole arrangement for stimulating cardiac activity.
  • an injection of stimulation signals generally is possible at the surface of intra-cardiac tissue, an electrode being in contact with intra-cardiac tissue in order to allow an injection of stimulation energy into the tissue.
  • LBBAP left bundle branch area pacing
  • an electrode pole arranged on an electrode lead shall engage with intra-cardiac tissue in the range of the septum of the heart in the vicinity of the left bundle branch.
  • a stimulation signal is generated at an energy that allows for a reliable stimulation by coupling to the conductive structure of the left bundle branch and by hence stimulating the left ventricle.
  • a so-called capture threshold test is performed in which the signal energy of the stimulation signal is adaptively changed to determine such minimum signal energy which still allows for a reliable capture, i.e., a coupling of energy to the conductive structure to allow for an effective stimulation.
  • the signal energy of the stimulation signal is progressively reduced from a maximum starting energy until no capture is observed any longer.
  • the value of the signal energy at which no capture is observed any more is determined to correspond to a capture threshold.
  • WO 2008/058265 A2 discloses a cardiac stimulation system and method which allow to deliver a left ventricle stimulator from a right ventricle lead system in the right ventricle chamber, into a right side of the septum at a first location, and transmuscularly from the first location to a second location along the left side of the septum.
  • the left ventricle stimulator is fixed at the second location for transmuscular stimulation of the left ventricular conduction system.
  • a biventricular stimulation system further includes a right ventricle stimulator also delivered by the right ventricle lead system to the first location along the right side of the septum for right ventricular stimulation.
  • US 2009/0276000 Al discloses a method for delivering physiological pacing by selecting an electrode implant site for sensing cardiac signals, which is in proximity to the hearts intrinsic conduction system.
  • An arrangement of multiple electrodes herein is arranged on a tip of a lead.
  • an implantable medical device for performing a cardiac stimulation comprises a generator device comprising a processing circuitry for processing electrical signals, an electrode lead connected to the generator device and extending from the generator device, the electrode lead comprising a lead body forming a distal end to be arranged on cardiac tissue within a patient’ s heart, in particular in the septum of a patient’ s heart, and an electrode pole arrangement comprising at least a first electrode pole and a second electrode pole, wherein the processing circuitry is configured to generate an electrical stimulation signal and to provide the electrical stimulation signal to said electrode pole arrangement for stimulating cardiac activity.
  • the processing circuitry is configured to measure, using said electrode pole arrangement, an impedance curve indicative of a stimulated cardiac activity in response to said electrical stimulation signal and to derive information indicative of a stimulation effectiveness of said electrical stimulation signal based on said impedance curve.
  • the implantable medical device comprises a generator device and an electrode lead connected to the generator device.
  • the electrode lead extends from the generator device and comprises a lead body forming a distal end to be arranged on cardiac tissue within a patient's heart, in the septum of a patient’s heart.
  • An electrode pole arrangement comprising electrode poles arranged on the electrode lead and/or on the generator device, is used to output electrical stimulation signals such that by means of the electrode pole arrangement an electrical stimulation of a desired cardiac region may be achieved.
  • the processing circuitry generates, during operation, electrical stimulation signals and provides the electrical stimulation signals to the electrode pole arrangement for stimulating cardiac activity.
  • a cardiac stimulation in particular a cardiac pacing
  • the implantable medical device for example functioning as a CRT device, in particular a CRT-P or CRT-D device (CRT: cardiac resynchronization therapy).
  • the implantable medical device may function as an IPG or ICD device (IPG: implantable pulse generator; ICD: implantable cardioverter defibrillator).
  • a cardiac stimulation of a desired kind Prior to operation, in an initial calibration phase, or repeatedly during operation it may be desired to evaluate whether a cardiac stimulation of a desired kind is obtained in response to an electrical stimulation signal. It herein is desired to be able to evaluate a cardiac stimulation in order to distinguish between different types of stimulations, for example no capture (corresponding to a situation in which no identifiable stimulation is observed in response to the output of an electrical stimulation signal), a selective left bundle branch area pacing (selective LBBAP, corresponding to a stimulation of only the left bundle branch resulting in a stimulated left ventricular activity), a non-selective left bundle branch area pacing (non- selective LBBAP, resulting in a stimulation of the left bundle branch and the right bundle branch and/or the septum), or a right bundle branch area pacing (RBBAP, corresponding to a stimulation of the right bundle branch and/or or the septum alone, without a stimulation of the left bundle branch).
  • no capture corresponding to a situation in which no identifiable stimulation is
  • LBBAP left bundle branch area pacing
  • the processing circuitry is configured to measure, using the electrode pole arrangement, an impedance curve indicative of a stimulated cardiac activity in response to an electrical stimulation signal and to derive information indicative of a stimulation effectiveness of the electrical stimulation signal based on the impedance curve.
  • an impedance curve is measured, and the impedance curve is evaluated in order to determine, based on the impedance curve, whether the outputting of the electrical stimulation signal results in a desired stimulated cardiac activity.
  • Based on an impedance measurement it hence is assessed whether a particular electrical stimulation signal effectively causes a desired stimulation, wherein based on the assessment a subsequent electrical stimulation signal may be adapted in order to establish a reliable stimulation, for example within a capture threshold test.
  • an impedance measurement is performed, and based on the impedance measurement a stimulated cardiac activity is evaluated.
  • the impedance measurement is carried out using the electrode pole arrangement of the implantable medical device.
  • the same electrode poles may be used for outputting the electrical stimulation signal and for performing the impedance measurement.
  • different sets of electrode poles are used for outputting the electrical stimulation signal and for performing the impedance measurement.
  • an impedance curve is recorded which is correlated with an electrical stimulation signal.
  • An electrical stimulation signal may for example cause cardiac activity, which is identifiable in an electrocardiogram, for example in the shape of a so-called QRS complex.
  • the impedance measurement may be synchronized to an electrocardiogram signal, such that the impedance measurement is correlated and synchronized with a cardiac contraction event in the electrocardiogram signal, for example a QRS complex in the electrocardiogram signal corresponding to a ventricular contraction event.
  • the stimulation effectiveness may in particular be determined by assessing a shape of the impedance curve. This is based on the finding that different types of ventricular contractions result in different impedance curves, e.g. a synchronous right and left ventricular contraction resulting in a different impedance curve than an asynchronous right and left ventricular contraction or a sole right ventricular contraction.
  • information may be derived indicative of a stimulation effectiveness, indicating e.g. whether a desired capture of the left bundle branch is obtained to cause a left bundle branch area pacing for stimulating in a left ventricular activity.
  • a signal processing of the impedance curve may be applied to determine one or multiple characteristic metrics.
  • a maximum or minimum amplitude of the impedance curve may be determined.
  • a temporal location of a maximum or minimum amplitude of the impedance curve may be determined.
  • an area under the impedance curve may be determined.
  • a signal width of a defined portion of the impedance curve may be determined, for example a temporal width in between zerocrossings of the impedance curve.
  • a derivative of the impedance curve may be determined, for example a maximum or minimum derivative value of the impedance curve to assess a steepness of the curve.
  • characteristic metrics of the impedance curve may be determined and assessed, for example relating to the positions of zero-crossings, maximum or minimum values, area values under certain portions of the curve, first, second or third derivative values or the like.
  • the processing circuitry is configured to compare the impedance curve to a reference impedance curve and to derive the information indicative of a stimulation effectiveness of the electrical stimulation signal based on the comparison.
  • the reference impedance curve may for example be predefined and stored within the processing circuitry, namely within an electronic memory of the processing circuitry.
  • the reference impedance curve may correspond to an impedance curve as obtained for one or multiple prior stimulation signals, for example an average of multiple prior impedance curves.
  • certain characteristic measures may be determined indicative of a difference between the impedance curve of the current electrical stimulation signal and the reference impedance curve. For example, a difference in maximum or minimum values, a difference in a temporal location of maximum or minimum values, and/or a difference area in between the impedance curve and the reference impedance curve may be determined.
  • a stimulation of the right bundle branch without an effective stimulation of the left bundle branch may result in an impedance curve in which a maximum is reached at a rather late point in time (during a cardiac cycle, e.g. in correlation to a start of contraction, e.g. the start of a QRS complex in an electrocardiogram signal).
  • a maximum in the impedance curve may occur substantially earlier than for the impedance curve corresponding to the right bundle branch stimulation alone.
  • the measurement of the impedance curve may be synchronized with an electrocardiogram signal and hence with a cardiac rhythm.
  • the measurement of the impedance curve may be synchronized with the output of the electrical stimulation signal, such that the impedance curve is measured within a defined time period in which a stimulated cardiac activity is expected following the outputting of the electrical stimulation signal.
  • the processing circuitry is configured, for deriving said information indicative of a stimulation effectiveness of said electrical stimulation signal, to evaluate based on said impedance curve whether a left ventricular activity is identifiable in response to the electrical stimulation signal.
  • the left ventricular activity may result from a left bundle branch area pacing, that is the coupling of the electrical stimulation signal to the left bundle branch.
  • the left ventricular activity may result from a left ventricular stimulation using a left ventricular electrode lead extending into the left ventricle.
  • the processing circuitry is configured to measure, repeatedly, an impedance curve in response to the outputting of an electrical stimulation signal in a capture threshold test.
  • stimulation energy shall be determined which reliably results in a desired capture and hence a desired stimulated cardiac activity.
  • stimulation signals may for example be repeatedly generated and output, wherein the energy of the stimulation signals may for example be progressively reduced starting from a maximum starting energy, until a capture loss is identified.
  • the signal energy at which (for the first time) a capture loss is observed corresponds to the capture threshold above which it is assumed that a reliable capture may be obtained, such that, during subsequent operation, the signal energy of the stimulation signal is set to a value above the threshold.
  • the processing circuitry is configured, for conducting a capture threshold test, to repeatedly generate an electrical stimulation signal, to provide the electrical stimulation signal to the electrode pole arrangement for stimulating cardiac activity, to measure an impedance curve indicative of a stimulated cardiac activity in response to the electrical stimulation signal and to derive information indicative of a stimulation effectiveness of the electrical stimulation signal based on the impedance curve.
  • a capture threshold test hence, repeated impedance measurements are carried out, wherein for each electrical stimulation signal an impedance curve is recorded and assessed.
  • a capture is obtained resulting in a stimulated left ventricular activity. Only if this is the case the capture is assumed to be effective, such that within the threshold test a signal energy is determined such that a desired capture is reliably obtained.
  • the capture threshold test it hence is not only distinguished between an effective stimulation (resulting in any stimulated activity whatsoever) and a non-effective stimulation, but it may be distinguished between a desired capture corresponding to an effective stimulation of a desired conductive structure, e.g. the left bundle branch, and a capture which does not include a stimulation of the desired conductive structure, e.g. the left bundle branch.
  • the capture threshold test may be automatically conducted by the implantable medical device prior to operation, e.g. in an initial calibration phase upon initial implantation, and/or repeatedly during operation, for example once or multiple times per day.
  • the energy of the electrical stimulation signal may be set such that during subsequent operation a reliable stimulation is obtained.
  • the processing circuitry is configured to adapt a signal strength of a current electrical stimulation signal with respect to a prior electrical stimulation signal during the capture threshold test based on information indicative of a stimulation effectiveness of the prior electrical stimulation signal. By repeating such measurements, for example starting from a maximum starting energy and by progressively reducing the signal energy until a non-effective stimulation of a desired structure is detected, a capture threshold is determined and the signal energy for subsequent operation may be set to a value above the threshold.
  • a capture threshold test it may be observed whether for a current stimulation signal a capture of a desired type is obtained. If this is the case, the signal energy is further reduced, until no effective stimulation of a desired, particular cardiac structure is observed, upon which the threshold is identified and the signal energy for subsequent operation may be set to a value above the threshold.
  • the assessment of a stimulation effectiveness may also be employed during regular operation, outside of a capture threshold test. For example, based on a measured impedance curve, it may be assessed whether during operation a desired stimulation in response to an electrical stimulation signal is obtained during a cardiac cycle, for example a left bundle branch stimulation. If, according to the impedance curve, it is determined that the desired structure (for example the left bundle branch) is not effectively stimulated, a backup pulse of a higher stimulation energy may be output.
  • the signal energy of a stimulation pulse may be adaptively changed and hence automatically adapted during operation.
  • the electrical stimulation signal may have the shape of an electrical stimulation pulse.
  • Such pulse may have one or multiple pulse phases of positive and/or negative amplitudes.
  • the processing circuitry in one embodiment is configured to generate electrical excitation signals which are output by means of the electrode pole arrangement.
  • response signals are received, which are processed by the processing circuitry of the generator device.
  • the processing circuitry may be configured to repeatedly generate at least one electrical excitation signal and provide said at least one electrical excitation signal to said electrode pole arrangement for outputting by said electrode pole arrangement, to repeatedly receive, using said electrode pole arrangement, at least one electrical response signal in response to said at least one electrical excitation signal, to derive, from said at least one electrical excitation signal and from said at least one electrical response signal, an electrical impedance value and to determine, based on a multiplicity of electrical impedance values, said impedance curve. Electrical excitation signals hence are repeatedly generated by the processing circuitry and are output via the electrode pole arrangement.
  • the electrical excitation signals preferably have a signal energy below a stimulation threshold, such that the electrical excitation signals used for the impedance measurements do not cause a stimulation of tissue.
  • An electrical excitation signal generated by the processing circuitry for outputting by the electrode pole arrangement may for example be a current signal produced by a defined current source, in which case the electrical response signal is a voltage signal. From the excitation signal and from the associated response signal, hence, an electrical impedance may be computed, wherein the impedance calculation is repeated such that an impedance curve is obtained.
  • an electrical excitation signal generated by the processing circuitry for outputting by the electrode pole arrangement is a voltage signal produced by a defined voltage source, in which case the electrical response signal is a current signal.
  • an impedance value may be computed, wherein the impedance calculation is repeated such that an impedance curve is obtained.
  • electrical excitation signals as generated by the processing circuitry to be output by the electrode pole arrangement are biphasic electrical pulse signals.
  • Such biphasic electrical pulse signals may be formed by a first pulse section having a positive amplitude and a consecutive, second pulse section having a negative amplitude, or vice versa.
  • the first electrode of the electrode pole arrangement is arranged on the distal end of the lead body and is configured to be inserted into cardiac tissue.
  • the first electrode pole is arranged on the distal end of the lead body and is configured to be inserted into cardiac tissue to operatively engage with a conductive structure of the left bundle branch in intra-cardiac tissue.
  • the first electrode pole may for example have the shape of a helical screw which may be inserted into intra-cardiac tissue by screwing the helical screw into tissue.
  • the first electrode pole may have the shape of a pike or a tine protruding from the distal end of the lead body and being configured for insertion into intra-cardiac tissue.
  • the second electrode pole is arranged on the lead body at a location proximal to the first electrode pole or on the generator device. If the second electrode pole is arranged on the lead body proximally with respect to the distal end, the second electrode pole may for example have the shape of a ring electrode extending circumferentially about the lead body. If the second electrode pole is arranged on the generator device, the second electrode pole may for example be formed by the housing or a housing section of the generator device. Further electrode poles may be present and may be arranged on the lead body of the electrode lead or on the housing of the generator device or on another lead connected to the generator device.
  • the first electrode pole and the second electrode pole form a first pair of electrode poles.
  • the processing circuitry herein is configured to repeatedly generate a first electrical excitation signal for outputting by the first pair of electrode poles and to receive, using the first pair of electrode poles, a first electrical response signal in response to the first electrical excitation signal.
  • the processing circuitry is configured to derive a first impedance curve from multiple first electrical excitation signals and multiple first electrical response signals.
  • First electrical excitation signals hence are output using the first pair of electrode poles formed between the first electrode pole, e.g. on the distal end of the lead body, and the second electrode pole, e.g. arranged on the housing of the generator device.
  • the electrode pole arrangement may comprise one or multiple further electrode poles.
  • a first electrode pole may be arranged on the distal end of the lead body
  • a second electrode pole may be arranged on the housing of the generator device
  • a third electrode pole may be arranged at a proximal location on the lead body or on another lead.
  • a second pair of electrode poles may be formed by one of the first electrode pole and the second electrode pole together with the third electrode pole.
  • the processing circuitry may be configured to repeatedly generate a second electrical excitation signal for outputting by the second pair of electrode poles and to receive, using the second pair of electrode poles, a second electrical response signal in response to the second electrical excitation signal.
  • the processing circuitry is configured to derive a second impedance curve from multiple second electrical excitation signals and multiple second electrical response signals.
  • a third pair of electrode poles may be formed by the other of the first electrode pole and the second electrode pole together with the third electrode pole.
  • the processing circuitry is configured to repeatedly generate a third electrical excitation signal for outputting by the third pair of electrode poles and to receive, using the third pair of electrode poles, a third electrical response signal in response to the third electrical excitation signal.
  • the processing circuitry is configured to derive a third impedance curve from multiple third electrical excitation signals and multiple third electrical response signals.
  • impedance curves may be derived and may be assessed.
  • One impedance curve may be indicative of the impedance in between the first electrode pole on the distal end of the lead body and the second electrode pole e.g. formed by the housing of the generator device.
  • Another impedance curve may be indicative of the impedance between the first electrode pole and the third electrode pole e.g. arranged proximally with respect to the first electrode pole on the lead body.
  • Yet another impedance curve may be indicative of the impedance in between the second electrode pole e.g. formed by the housing of the generator device and the third electrode pole e.g. arranged proximally with respect to the first electrode pole on the lead body.
  • the different impedance curves may be processed each by itself or in a combined fashion.
  • the processing circuitry is configured to generate multiple electrical excitation signals to be output using different pairs of electrode poles of the electrode pole arrangement by employing a time multiplexing.
  • electrical excitation signals for example pulse signals, may be output in an alternating, staggered fashion such that a first electrical excitation signal to be output by a first pair of electrode poles of the electrode pole arrangement is followed by a second electrical excitation signal to be output by a second pair of electrode poles, which again is followed by a third electrical excitation signal to be output by a third pair of electrode poles, upon which again a first electrical excitation signal is produced and output.
  • electrical excitation signals are continuously generated and output in a multiplexed fashion, such that impedance values may be continuously recorded.
  • the different pairs of electrode poles may also be used for outputting electrical stimulation signals for causing a stimulation action, for example to cause a spatially differentiated stimulation of cardiac structures, for example to cause a left bundle branch pacing as well as a stimulation of the cardiac septum and hence a right ventricular stimulation.
  • the processing circuitry may be configured to switch between different pairs of electrode poles for outputting electrical stimulation signals, such that in case of a capture loss it may be switched automatically from one stimulation polarity to another.
  • the processing circuitry may be configured to generate and output electrical stimulation signals using different stimulation vectors spanned by different pairs of electrode poles.
  • an impedance curve may be measured and may be assessed in order to evaluate an obtained capture.
  • that stimulation vector may be used during operation which results in the optimum capture, e.g. that stimulation vector resulting in the narrowest QRS complex indicative of a most effective capture.
  • the implantable medical device may be a one-chamber IPG device.
  • the implantable medical device may be a two-chamber IPG device.
  • the implantable medical device may be a one-chamber ICD device.
  • the implantable medical device may be a two-chamber ICD device.
  • the implantable medical device may be a CRT device (CRT-P or CRT-D).
  • the electrode lead may be a single electrode lead further comprising an atrial dipole for sensing atrial signals, the atrial dipole being floatingly arranged within an atrium of the patient’s heart.
  • the atrial dipole may comprise first and second proximal ring electrodes.
  • a method for operating an implantable medical device for performing a cardiac stimulation comprises: processing electrical signals using a processing circuitry of a generator device of the implantable medical device, wherein an electrode lead is connected to the generator device and extends from the generator device, the electrode lead comprising a lead body forming a distal end to be arranged on cardiac tissue within a patient’s heart, in particular in the septum of a patient’s heart; generating, using the processing circuitry, an electrical stimulation signal and providing the electrical stimulation signal to an electrode pole arrangement for stimulating cardiac activity, the electrode pole arrangement comprising at least a first electrode pole and a second electrode pole; measuring, using the processing circuitry and said electrode pole arrangement, an impedance curve indicative of a stimulated cardiac activity in response to said electrical stimulation signal; and deriving information indicative of a stimulation effectiveness of said electrical stimulation signal based on said impedance curve.
  • Fig. 1 shows a schematic view of an implantable medical device having a generator device and electrode leads
  • Fig. 2 shows a schematic drawing of a distal end of an electrode lead in an implanted state
  • Fig. 3 shows the implantable medical stimulation device
  • Fig. 4 shows an example of impedance curves as measured e.g. during a capture threshold test
  • Fig. 5 shows biphasic excitation pulses as output for performing impedance measurements.
  • Fig. 1 shows, in a schematic drawing, the human heart H comprising the right atrium RA, the right ventricle RV, the left atrium LA and the left ventricle LV.
  • An implantable medical device 1 is implanted in a patient, the implantable medical device 1 comprising a generator 12 connected to leads 10, 11 extending from the generator 12 through the superior vena V into the patient's heart H.
  • leads 10, 11 electrical signals for providing a pacing action in the heart H shall be injected into intra-cardiac tissue potentially at different locations within the heart, and sense signals may be received.
  • Fig. 1 shows, in a schematic drawing, the human heart H comprising the right atrium RA, the right ventricle RV, the left atrium LA and the left ventricle LV.
  • An implantable medical device 1 is implanted in a patient, the implantable medical device 1 comprising a generator 12 connected to leads 10, 11 extending from the generator 12 through the superior vena V into the patient's heart H.
  • leads 10, 11
  • an electrode lead 10 is implanted into the heart H such that it extends into the right ventricle RV of the heart H and, at a distal end 101 of a lead body 100, is arranged on intra-cardiac tissue at the septum M in between the right ventricle RV and the left ventricle LV of the heart H.
  • An electrode lead 11 in turn is implanted such that it reaches into the right atrium RA.
  • An implantable medical device 1 as concerned herein may generally be a cardiac stimulation device such as a cardiac pacemaker device.
  • a stimulation device of this kind comprises a generator 12, as shown in Fig. 1, which may be subcutaneously implanted in a patient at a location remote from the heart H, one or multiple leads 10, 11 extending from the generator 12 into the heart H for emitting stimulation signals in the heart H or for obtaining sense signals at one or multiple locations from the heart H.
  • the leads 10, 11 each form a generally longitudinal, tubular body 100, which reaches into the heart H and is anchored at a location of interest within the heart H.
  • the implantable medical device 1 as described herein in particular shall serve to provide a so-called left bundle branch area pacing, in short LBBAP.
  • the electrode lead 10 is implanted such that the lead body 100, with the distal end 101, is placed on tissue on the septum M such that it engages with tissue and reaches into tissue in order to couple to the left bundle branch LBB which, as part of the conductive structure of the patient’s heart H, is coupled via the so-called His bundle HIS to the atrioventricular node AVN and runs in parallel to the right bundle branch RBB.
  • the left bundle branch LBB extends within myocardial tissue around the vertex of the left ventricle LV and conducts excitation signals for exciting tissue in the region of the left ventricle LV.
  • the electrode lead 10 comprises a electrode pole 102 which is arranged on and protrudes from the distal end 101 of the lead body 100.
  • the electrode pole 102 is formed by a helical spiral and is shaped such that it may be screwed into tissue in order to electrically couple to tissue and provide for a mechanical anchoring of the electrode lead 10 on tissue.
  • the electrode lead 10 comprises a another electrode pole 103 which is formed by a ring electrode arranged proximally with respect to the electrode pole 102 on the lead body 100 of the electrode lead 10.
  • the electrode pole 102 formed by the helical spiral is engaged with tissue and reaches into tissue such that it electrically couples to the conductive structure within the myocardial tissue of the septum M, in particular the left bundle branch LBB, in order to enable a stimulation of the conductive structure by coupling stimulation signals to the conductive structure.
  • the electrode pole 103 may electrically contact tissue in that it fully or at least partially rests within tissue and hence electrically couples to tissue.
  • the electrode lead 10 is inserted, from the region of the right ventricle RV, into tissue such that the electrode pole 102 at the distal end 101 reaches a sufficient insertion depth within the tissue in order to couple to a desired conductive structure.
  • the electrode pole 103 shall establish a desired coupling to tissue.
  • electrical stimulation signals shall be output to couple into tissue in particular in the region of the left bundle branch LBB, as shown in Fig. 2, such that a spatially differentiated stimulation of the conductive structure of the left bundle branch LBB is obtained, causing a stimulated left ventricular activity, for example in the context of a cardiac resynchronization therapy (CRT).
  • CRT cardiac resynchronization therapy
  • electrical stimulation signals in particular electrical stimulation pulses having one or multiple phases, exhibiting a signal energy which is sufficient to cause a reliable stimulation of a desired structure, in particular the left bundle branch LBB, while avoiding an excessive load of the electrical energy resources of the implantable medical device 1.
  • a capture threshold test is carried out at the initial startup of the implantable medical device 1 and repeatedly during operation, for example once or multiple times per day, in order to assess and set a signal strength for an electrical stimulation signal to cause a reliable stimulation of a desired structure.
  • electrical stimulation signals are generated and output starting at a maximum start energy, wherein the signal energy is progressively reduced until a capture loss is detected.
  • the signal energy at the capture loss is identified as a capture threshold.
  • the signal energy for the electrical stimulation signal during subsequent operation is then set to a value above the threshold in order to obtain a reliable capture of a desired structure.
  • a spatially dedicated stimulation of a certain conductive structure namely the left bundle branch LBB, shall be established, it is desired to evaluate during the capture threshold test whether a capture of the desired structure is obtained, in comparison to just any capture resulting in any cardiac activity, for example a right ventricular activity.
  • impedance curves which are recorded in response to an electrical stimulation signal in order to evaluate, based on an impedance curve, whether a desired structure is effectively stimulated as a result of the outputting of the electrical stimulation signal. Based on impedance measurements it hence is assessed what type of capture is obtained, such that during a capture threshold test it not only may be assessed whether a capture is obtained at all, but also what type of capture is present.
  • an impedance curve measured in response to an electrical stimulation signal substantially depends on the contraction event resulting from the stimulation. Namely, a stimulation causing a cardiac contraction of both the left ventricle and the right ventricle will result in an impedance curve which substantially differs from an impedance curve for a stimulation resulting in a right ventricular contraction alone or a left ventricular contraction alone.
  • the effectiveness of a stimulation may be assessed, and it may be determined whether a capture of a desired type, namely, in the example of Fig. 2, a capture to the left bundle branch LBB, is obtained.
  • impedance curves may be measured, for example in between the electrode pole 102 and the electrode pole 103 (Zsi P ), between the electrode pole 102 and an electrode pole 121 formed by the housing of the generator device 12 (Z-ri P u) and between the electrode pole 103 and the electrode pole 121 (Zpingu).
  • the impedance measurements are carried out in a connected state of the electrode lead 10 in that the processing circuitry 120 of the generator device 12 generates electrical excitation signals which are output using a respective pair of electrode poles 102, 103, 121.
  • electrical response signals are received, such that by correlating the electrical excitation signals and the electrical response signals impedance curves for the different pairs of electrode poles 102, 103, 121 may be computed and assessed.
  • a first pair of electrode poles is formed by the electrode pole 102 and the electrode pole 121 (ZTI P U).
  • a second pair of electrode poles is formed by the electrode pole 102 and the electrode pole 103 (ZBI P ).
  • a third pair of electrode poles is formed by the electrode pole 103 and the electrode pole 121 (ZRi ng u).
  • the electrical excitation signals as generated by the processing circuitry 120 to be output by a respective pair of electrode poles 102, 103, 121 are current signals which are generated by a controlled current source.
  • the electrical response signals are voltage signals.
  • the electrical excitation signals as generated by the processing circuitry 120 to be output by a respective pair of electrode poles 102, 103, 121 are voltage signals which are generated by a controlled voltage source.
  • the electrical response signals are current signals.
  • impedance curves are obtained which may be assessed to evaluate a stimulation effectiveness indicative of a capture of a certain cardiac structure.
  • an electrical stimulation signal is generated and is output using the electrode pole arrangement formed by the electrode poles 102, 103, 121, for example by injecting the electrical stimulation signal using a stimulation vector formed by the electrode poles 102, 103 of the electrode lead 10.
  • an impedance curve using a particular pair of electrodes 102, 103, 121 is measured.
  • the impedance curve may then be assessed by evaluating the shape of the impedance curve in order to derive information indicative of a stimulation effectiveness of the electrical excitation signal.
  • different impedance curves in response to an electrical stimulation signal may be measured, wherein the impedance curves may be processed and evaluated in a combined fashion in order to derive information with respect to a stimulation effectiveness from the combination of the impedance curves.
  • the impedance curves Cl, C2 may be measured and recorded in a time range for example corresponding to a QRS complex of a ventricular contraction event V(i), V(i+1) within a cardiac cycle and hence in a time range of ventricular depolarization activity in between a so-called P wave and a subsequent T wave.
  • the impedance curve Cl may for example correspond to a situation in which a capture only to the right bundle branch RBB is obtained, whereas the left bundle branch LBB is not effectively stimulated.
  • the impedance curve C2 in contrast may relate to a situation in which a selective left bundle branch stimulation, corresponding to a stimulation of the left bundle branch LBB alone, or a non-selective left bundle branch stimulation, corresponding to a stimulation of both the left bundle branch LBB and the right bundle branch RBB and/or the septum M, is obtained.
  • the shape of the impedance curves Cl, C2 substantially differs, such that by evaluating the shape of the impedance curves Cl, C2 one capture scenario may be distinguished from another.
  • the impedance curves Cl, C2 in the example of Fig. 4 may for example be evaluated by assessing the maximum amplitude Ml, M2 of the respective curve Cl, C2, the temporal location tMi, tM2 of the maximum amplitude Ml, M2, a signal width W of a signal portion in between zero-crossings of the respective curve Cl, C2, or an area under a curve.
  • a particular curve Cl, C2 may be compared to a reference curve, wherein certain characteristic metrics may be determined based on the comparison, for example a difference area A between the different curves or a difference in the maximum amplitude values Ml, M2, or a difference in their temporal locations tMi, tM2.
  • a reference curve herein may be pre-stored.
  • a current impedance curve Cl, C2 may be compared to a previous impedance curve C2, Cl resulting from a previous stimulation event, such that the previously recorded impedance curve serves as a reference curve.
  • the assessment of a capture may in particular be useful in a capture threshold test in which, during the initial startup of the implantable medical device 1 or repeatedly during operation, a capture threshold is determined indicative of a signal energy below which a capture loss is to be expected.
  • electrical stimulation signals may be repeatedly generated, starting from a maximum signal energy and progressively reducing the signal energy of the electrical stimulation signals.
  • an impedance curve Cl, C2 is measured and evaluated, wherein based on e.g. a change in the impedance curve Cl, C2 from one electrical stimulation signal to another it is determined whether a loss of capture with relation to a desired cardiac region or structure is likely present.
  • an impedance curve similar to the impedance curve C2 indicative of a capture to the left bundle branch LBB may be obtained. If at a certain, reduced signal energy the impedance curve substantially deviates from the impedance curve C2 and approaches for example towards the impedance curve Cl relating to a capture of only the right bundle branch RBB, this may be assumed to indicate a loss of capture to the left bundle branch LBB, such that within the capture threshold test a capture threshold is set. For subsequent operation, then, a signal energy is set above the capture threshold.
  • the impedance curve C2 for example may serve as a reference curve indicative of an effective capture to the left bundle branch LBB.
  • a degree of deviation from the reference curve C2 herein may be assessed for example based on a size change of the difference area A with respect to the reference curve C2, or based on a change of the temporal location of the maximum amplitude with respect to the temporal location tM2 of the maximum amplitude M2 of the reference curve C2.
  • the processing circuitry 120 For measuring an impedance curve Cl, C2, the processing circuitry 120 generates excitation signals to be output by a respective pair of electrode poles 102, 103, 121, and receives corresponding response signals.
  • the processing for deriving impedance curves herein is carried out by the processing circuitry 120 within the generator device 12.
  • the processing circuitry 120 may be configured to communicate information relating to the impedance curves to an external device 2 resting outside of the patient, as is shown in Fig. 3, such that the external device 2 is enabled to process the impedance curves for further evaluation.
  • the processing circuitry 120 may for example produce, as electrical excitation signals, biphasic pulses Pl, P2, P3 to be output by the respective pair of electrode poles 102, 103, 121.
  • the pulses Pl, P2, P3 herein may be time multiplexed in that a first pulse Pl is generated to be output by a first pair of electrode poles 102, 103, 121, subsequently a second pulse P2 is generated to be output by a second pair of electrode poles 102, 103, 121, and subsequently a third pulse P3 is generated to be output by a third pair of electrode poles 102, 103, 121, upon which the sequence starts again.
  • one pulse Pl, P2, P3 is generated and output after the other, and for each excitation pulse Pl, P2, P3 a corresponding response signal is received and processed.
  • the idea underlying the invention is not limited to the embodiments described above, but may be implemented in an entirely different fashion.
  • An electrode pole arrangement of an implantable medical device may comprise two or more electrode poles, e.g. three electrode poles or more than three electrode poles. Hence, a different number of impedance curves may be recorded, wherein it in principle may suffice to record only a single impedance curve to derive information with respect to a stimulation effectiveness.
  • An implantable medical device may be configured for providing for a left bundle branch area pacing, but may, alternatively or in addition, implement different pacing functions.
  • V(i), V(i+1) Ventricular contraction event

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Abstract

Un dispositif médical implantable (1) pour effectuer une stimulation cardiaque comprend un dispositif générateur (12) comprenant un circuit de traitement (120) pour traiter des signaux électriques, un fil d'électrode (10, 11) connecté au dispositif générateur (12) et s'étendant à partir du dispositif générateur (12), le fil d'électrode (10) comprenant un corps de fil (100) formant une extrémité distale (101) à disposer sur un tissu cardiaque à l'intérieur du cœur d'un patient (H), et un agencement de pôles d'électrode comprenant au moins un premier pôle d'électrode (102) et un second pôle d'électrode (103, 121). Le circuit de traitement (120) est configuré pour générer un signal de stimulation électrique et pour fournir le signal de stimulation électrique audit agencement de pôles d'électrode pour stimuler l'activité cardiaque. Le circuit de traitement (120) est en outre configuré pour mesurer, à l'aide dudit agencement de pôles d'électrode, une courbe d'impédance (C1, C2) indicative d'une activité cardiaque stimulée en réponse audit signal de stimulation électrique et pour dériver des informations indiquant une efficacité de stimulation dudit signal de stimulation électrique sur la base de ladite courbe d'impédance (C1, C2).
PCT/EP2024/079683 2023-11-22 2024-10-21 Dispositif médical implantable pour réaliser une stimulation cardiaque Pending WO2025108644A1 (fr)

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5003976A (en) * 1987-09-28 1991-04-02 Eckhard Alt Cardiac and pulmonary physiological analysis via intracardiac measurements with a single sensor
WO2008058265A2 (fr) 2006-11-08 2008-05-15 Emerge Medsystems Llc Dérivations de stimulation cardiaque transmusculaire pour le ventricule gauche et systèmes et procédés apparentés
US20090276000A1 (en) 2002-09-30 2009-11-05 Medtronic, Inc. Pacing method
US20130218222A1 (en) * 2012-02-16 2013-08-22 Biotronik Se & Co. Kg Cardiac stimulator for cardiac contractility modulation
US8965495B2 (en) * 2010-08-30 2015-02-24 Biotronik Se & Co. Kg Implantable electronic therapy device
US20180140847A1 (en) * 2016-11-24 2018-05-24 Biotronik Se & Co. Kg Bi-ventricular implantable medical device
EP2578268B1 (fr) * 2011-10-06 2020-07-22 BIOTRONIK SE & Co. KG Capteur de température pour un appareil médical implantable

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5003976A (en) * 1987-09-28 1991-04-02 Eckhard Alt Cardiac and pulmonary physiological analysis via intracardiac measurements with a single sensor
US20090276000A1 (en) 2002-09-30 2009-11-05 Medtronic, Inc. Pacing method
WO2008058265A2 (fr) 2006-11-08 2008-05-15 Emerge Medsystems Llc Dérivations de stimulation cardiaque transmusculaire pour le ventricule gauche et systèmes et procédés apparentés
US8965495B2 (en) * 2010-08-30 2015-02-24 Biotronik Se & Co. Kg Implantable electronic therapy device
EP2578268B1 (fr) * 2011-10-06 2020-07-22 BIOTRONIK SE & Co. KG Capteur de température pour un appareil médical implantable
US20130218222A1 (en) * 2012-02-16 2013-08-22 Biotronik Se & Co. Kg Cardiac stimulator for cardiac contractility modulation
US20180140847A1 (en) * 2016-11-24 2018-05-24 Biotronik Se & Co. Kg Bi-ventricular implantable medical device

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