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WO1995027531A1 - Stimulateur cardiaque a commande physiologique et son procede - Google Patents

Stimulateur cardiaque a commande physiologique et son procede Download PDF

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Publication number
WO1995027531A1
WO1995027531A1 PCT/US1995/003642 US9503642W WO9527531A1 WO 1995027531 A1 WO1995027531 A1 WO 1995027531A1 US 9503642 W US9503642 W US 9503642W WO 9527531 A1 WO9527531 A1 WO 9527531A1
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WO
WIPO (PCT)
Prior art keywords
cardiac
detecting
implantable
stimulating device
heart
Prior art date
Application number
PCT/US1995/003642
Other languages
English (en)
Inventor
Kelly H. Mcclure
Lisa P. Weinberg
Original Assignee
Pacesetter, Inc.
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 Pacesetter, Inc. filed Critical Pacesetter, Inc.
Priority to AU22296/95A priority Critical patent/AU2229695A/en
Publication of WO1995027531A1 publication Critical patent/WO1995027531A1/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
    • 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
    • A61N1/36585—Heart stimulators controlled by a physiological parameter, e.g. heart potential controlled by two or more physical parameters
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00—Electrotherapy; Circuits therefor
    • A61N1/18—Applying electric currents by contact electrodes
    • A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
    • A61N1/38—Applying electric currents by contact electrodes alternating or intermittent currents for producing shock effects
    • A61N1/39—Heart defibrillators
    • A61N1/3956—Implantable devices for applying electric shocks to the heart, e.g. for cardioversion
    • A61N1/3962—Implantable devices for applying electric shocks to the heart, e.g. for cardioversion in combination with another heart therapy
    • A61N1/39622—Pacing therapy
    • 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
    • A61N1/36571—Heart stimulators controlled by a physiological parameter, e.g. heart potential controlled by a physiological quantity other than heart potential, e.g. blood pressure controlled by blood flow rate, e.g. blood velocity or cardiac output
    • 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
    • A61N1/36578—Heart stimulators controlled by a physiological parameter, e.g. heart potential controlled by a physiological quantity other than heart potential, e.g. blood pressure controlled by mechanical motion of the heart wall, e.g. measured by an accelerometer or microphone

Definitions

  • This invention relates generally to irnplantable cardiac stimulating devices, and particularly to irnplantable stimulating devices that include sensors for detecting mechanical cardiac contractions in a patient. More particularly, this invention is directed toward a demand-type irnplantable cardiac stimulating device and a method of stimulating the heart which uses a mechanical contraction detector to determine whether to inhibit the generation of stimulation pulses.
  • a pacemaker is an irnplantable medical device which delivers electrical stimulation pulses to cardiac tissue to relieve symptoms associated with bradycardia — a condition in which a patient cannot maintain a physiologically acceptable heart rate.
  • Early pacemakers delivered stimulation pulses at fixed intervals in order to maintain a predetermined heart rate, which was typically set at a rate deemed to be appropriate for the patient at rest. The predetermined rate was usually set at the time the pacemaker was implanted, and in more advanced devices, could be set remotely by a medical practitioner after implantation.
  • the electrical cardiac signals include, for example, P-waves and R-waves corresponding to the depolarization of the atria and the ventricles, respectively.
  • Demand pacemakers are capable of detecting spontaneous electrical cardiac signals which occur within a predetermined time period (commonly referred to as the "alert period").
  • an escape interval is started.
  • the escape interval is comprised of a refractory period and an alert period.
  • the pacemaker ceases to be responsive to incoming signals. It is during the alert period that a naturally occurring electrical cardiac signal can be detected and a stimulation pulse will be inhibited.
  • a demand pacemaker will generate a stimulation pulse at the end of the escape interval.
  • Demand pacemakers proved to be extremely beneficial in that they successfully reduced or eliminated seriously debilitating and potentially lethal effects of bradycardia in many patients.
  • the demand pacemaker has the advantages of conserving current drain by allowing the patient's natural rhythm to occur and, more importantly, of potentially preventing the acceleration of an arrhythmia by not competing with the patient's natural rhythm.
  • Pacemakers that perform electrogram sensing for purposes of demand pacing present several drawbacks, particularly relating to signal processing, which have proven difficult to overcome. For example, it is extremely difficult to accurately sense the IEGM in the presence of noise or electromagnetic interference.
  • a burst or pulse of high frequency noise or EMI will falsely inhibit the pacemaker (i.e., a burst of noise is effectively envelope detected, resembling a single pulse, thereby mimicking an R-wave) .
  • a narrow bandpass filter e.g. 40-80 Hz
  • Residual polarization effects as a result of a stimulation pulse being delivered, also affect the electrogram sense amplifier's ability to sense properly. Residual polarization effects (commonly known as "afterpotentials") occur in the immediate vicinity of the pacing electrodes and depend largely on the implanted electrode's composition, size and surface area, in addition to, the energy content of the stimulation pulse. Indeed, most pacemakers enter a blanking period immediately after a stimulation pulse is delivered, during which time the sensing circuitry is deactivated for the specific purpose of avoiding undesirable sensing of afterpotentials. However, if the blanking interval is too short, or if the afterpotential is unduly large, the pacemaker will sense the afterpotential (also known as oversensing) and falsely inhibit the pacemaker.
  • afterpotentials also known as oversensing
  • a lead undergoes numerous changes at the point of contact with the cardiac tissue (also known as the site of injury) .
  • the body reacts to the lead electrode as it would any other foreign body by building up a capsule of fibrous, scar tissue around the lead electrode, effectively encapsulating and, advantageously, anchoring it in place.
  • changes in sensing thresholds can occur abruptly during the acute phase (that is, during at least the first month post- implant) , and gradually during the chronic phase of the lead. If the electrogram sense amplifier does not have an adequate safety margin, the pacemaker will not sense a true cardiac signal (also known as undersensing) .
  • Cross-sensing of electrical signals can also arise whenever a signal from one chamber is so large that it is sensed in the opposite chamber. For example, "far-field" R-waves originating from the ventricles are often observed on the atrial lead. Also, large output stimuli from one chamber may be cross-sensed by the other chamber. In either case, false inhibition may result.
  • unipolar-tip sensing occurs from the distal tip electrode to the pacemaker case.
  • Unipolar-ring sensing occurs from the distal ring electrode to the pacemaker case.
  • Bipolar sensing occurs between the distal tip and the distal ring electrode.
  • bipolar sensing is often chosen since it inherently has superior noise immunity to external interference signals, such as, myopotentials, EMI and noise.
  • bipolar sensing can also suffer from low amplitude signals if positioned poorly or oriented perpendicular to the electrical wavefront (effectively nulling the difference signal) .
  • arrhythmias such as low amplitude fibrillation
  • the irnplantable stimulation device incorporates automatic gain adjustment, or other types of automatic calibration and signal processing routines.
  • EMI and noise can corrupt these automatic routines.
  • pharmacological therapy, exercise and diurnal variations will also affect the amplitude of the IEGM.
  • Pacemakers which perform electrogram sensing must therefore make certain accommodations (e.g., additional blanking/refractory circuitry, discharge circuitry, software checking, etc.) to overcome the difficulties described above.
  • a mechanical contraction detector is provided which senses natural and evoked cardiac contractions and couples this information to control logic and timing circuitry within the implantable cardiac stimulating device to provide demand pacing therapy.
  • the term "depolarization” refers to the propagation of electrical activity in the cardiac muscle cells. That is, during each cardiac cycle, an action potential is spontaneously generated in the S-A node, or may be artificially generated by a stimulation pulse. The action potential then propagates through both atria, the A-V bundle and into the ventricles. Thus, a P-wave is caused by the propagation of the action potential as the atria depolarize prior to contraction, and an R-wave is caused by the propagation of the action potential as the ventricles depolarize prior to contraction.
  • the physical or "mechanical contraction" of the cardiac muscle begins a few milliseconds after this action potential begins and continues to contract for a few milliseconds after the action potential ends.
  • the present invention allows the implantable cardiac stimulating device to provide demand pacing therapy without the need for an electrogram sense amplifier.
  • the mechanical contraction detector can be used as the primary sensor, with an electrogram sense amplifier as a secondary sensor or for purposes of redundancy or waveform analysis.
  • the functional result of the mechanical contraction-based demand pacing system of the present invention is similar to the prior art electrogram-based demand pacing system, but does not suffer from the problems of electrogram sensing. That is, the present invention delivers stimulation pulses to the patient's heart in the absence of mechanical contractions, and inhibits stimulation pulses in the presence of detected mechanical contractions.
  • the present invention includes single-chamber pacing (e.g., WI or AAI modes), dual-chamber pacing (e.g., DDD, DDI mode, etc.), and atrial tracking modes (e.g., VDD mode) .
  • the present invention comprises a cardiac wall motion sensor to detect the physical or mechanical contraction of the heart.
  • the present invention preferably includes an accelerometer placed on one of a patch lead, a myocardial lead or an endocardial lead.
  • the output of the accelerometer can be used directly to detect cardiac wall motion, or can be processed to provide velocity (corresponding to contractility and sympathetic tone) or cardiac wall displacement (corresponding to blood flow and stroke volume) .
  • Other direct mechanical sensors that may be used to detect cardiac contractions include, for example, stroke volume (impedance sensors) , thermodilution, heart sounds, ventricular pressure, atrial pressure, or aortic pressure, etc.
  • the mechanical contraction detectors used in accordance with the present invention are not susceptible to interference from pulse-induced afterpotentials, noise, electromagnetic interference, cross-sensing, undersensing, oversensing, drugs, exercise, arrhythmias or diurnal variations.
  • the present invention further includes a method of stimulating the heart using a mechanical contraction detector for detecting natural cardiac contractions and inhibiting the output of stimulation pulses in the presence of a naturally occurring natural cardiac contractions.
  • Fig. 1 is a block diagram of an implantable cardiac stimulating device that is capable of providing demand pacing therapy based on mechanical contraction in accordance with the principles of the present invention
  • Fig. 2 shows a variety of locations for a mechanical contraction detector in combination with a variety of leads in contact with a patient's heart
  • Fig. 3 depicts a simplified flow diagram for controlling the calibration of the adaptive bandpass filter
  • Fig. 4 illustrates how intrinsic and evoked R-waves are observed on a surface electrocardiogram (ECG) , on an intracardiac ventricular electrogram (VTR EGM) , and at the output of the cardiac wall motion sensor, along with basic timing diagrams; and
  • Fig. 5 is an illustration of the relationship of the surface electrocardiogram (ECG) with other physiological events that occur during the cardiac cycle.
  • a block diagram is shown representing an implantable cardiac stimulating device 50 which performs mechanical contraction detection in accordance with the principles of the present invention.
  • the implantable cardiac stimulating device 50 as described below, is a combined pacing and cardioverting/defibrillator device capable of providing demand pacing therapy as well as higher energy therapies, such as cardioversion and defibrillation shocks.
  • mechanical contraction-based demand pacing can be easily implemented in a simpler device, such as a dedicated demand pacemaker, in view of the description below.
  • the implantable cardiac stimulating device 50 delivers therapeutic electrical stimulation to a patient's heart (not shown) through a pacing lead 52 and a shocking lead 62, proximal ends of which are connected to the implantable cardiac stimulating device 50, and distal ends being in contact with a selected region of cardiac tissue (not shown) .
  • a pacing lead 52 is used to deliver stimulation pulses generated by a pulse generator 54 (which may be conventional) in accordance with instructions provided by a control logic and timing circuitry 56.
  • a pulse generator 54 which may be conventional
  • the shocking lead 62 may be a single lead with two spaced-apart endocardial electrodes, or may take the form of two shocking leads attached to the myocardium.
  • the implantable cardiac stimulating device 50 operates as a demand pacemaker, in that the delivery of a stimulation pulse provided by the pulse generator 54 may be inhibited by a spontaneous cardiac contraction which occurs during an alert period determined by the control logic and timing circuitry 56.
  • the mechanical contraction detector 58 provides a control signal to the control logic and timing circuitry 56, indicative of whether a mechanical cardiac contraction has occurred.
  • the control logic and timing circuitry 56 determines if a sensed mechanical contraction occurred within the alert period, and if so, inhibits the pulse generator 54 from generating a stimulation pulse. Otherwise, stimulation pulses continue to be administered at the programmed rate.
  • the mechanical contraction detector 58 is a cardiac wall motion sensor.
  • the mechanical contraction detector 58 is shown in Fig. 1 as a separate element (e.g., a separate "sensor only" lead) , in the preferred embodiment, the mechanical contraction detector 58 is mechanically coupled to the patient's heart by a lead that is also used to administer therapeutic electrical stimulation (e.g., either the pacing lead 52 or the shocking lead 62) .
  • therapeutic electrical stimulation e.g., either the pacing lead 52 or the shocking lead 62
  • the pacing lead 52 and the shocking lead 62 are shown as physically separate leads, their respective electrodes may also be provided by a single lead (not shown) which includes a pacing, sensing, and shocking electrodes, as well as, a mechanical contraction detector.
  • the lead which contains the cardiac wall motion sensor may contain at least one (and perhaps all) of the electrodes that are used to deliver stimulation pulses, thereby advantageously reducing the number of leads that need to be implanted in the patient's body.
  • a variety of locations for a cardiac wall motion sensor are shown in combination with a variety of leads in contact with a patient's heart 78.
  • a mechanical contraction detector 58 (Fig. 1) could be employed at the distal end 82 of a ventricular endocardial lead 80, the distal end 92 of an atrial endocardial lead 90, or at the distal ends 98, 99 of an epicardial lead, such as, patch leads 94 or 96, respectively.
  • the preferred location would be the distal ends 82 and 92 of the ventricular and atrial leads 80 and 90, respectively.
  • One or more mechanical contraction detectors could also be located on a lead so that both the atrial and the ventricular physical muscle contractions can be detected.
  • a single lead is desirable to minimize the number of leads implanted.
  • a mechanical contraction detector 58 located at the distal end 82 of the ventricular lead 80 could pick up atrial contractions, it may be desirable to move the mechanical contraction detector 58 below (or near) the A-V valve, e.g., at location 84.
  • ventricular lead 80 it may be necessary to place two mechanical contraction detectors on the single ventricular lead, e.g., by placing one detector in the atrium at location 86 and one detector in the ventricle at location 82 or 84.
  • conventional electrogram sensing could be added as a redundant sensor or for waveform analysis.
  • ring electrodes could be added to the distal ends 82 or 92 of the ventricular or atrial lead, respectively, or a pair of electrodes could be located floating in the atrium at the proximal end (e.g., at location 86) of the ventricular lead 80.
  • electrogram sensing could be used in combination with a mechanical contraction sensor.
  • ring electrodes could be located in one chamber of the heart, either the ventricle or the atrium, and a mechanical contraction detector 58 could be used in the other chamber.
  • lead configurations may be used in accordance with the principles of the present invention, so as to not diminish the flexibility that a medical practitioner normally has when selecting leads that meet the needs of a particular patient.
  • other mechanical contraction detectors that may be used to detect physical cardiac contractions include, for example, stroke volume, thermodilution, heart sounds, ventricular pressure, atrial pressure, or aortic pressure, etc. These other sensors will be discussed below in conjunction with FIG. 5.
  • signals from the mechanical contraction detector 58 are received by a preamplifier and bandpass filter 60 within the implantable cardiac stimulating device 50.
  • the bandpass filter is an adaptive bandpass filter with is tunable to different center frequencies and/or bandwidths so that noise and other artifact signals, such as valve sounds, can be eliminated.
  • the preamplifier and bandpass filter 60 are tuned by the control logic and timing circuitry 56 to select relatively large amplitude, high slew rate signals that are associated with coherent cardiac contractions, and to reject signals caused by patient movements.
  • the preamplifier and bandpass filter 60 may further process the signals using conventional techniques, such as noise filtering, averaging, integrating or double-integrating.
  • the integral and double-integral of, for example, cardiac wall motion accelerations correspond to velocity and cardiac displacement, as described in commonly assigned, copending U.S. Patent Application Serial No. 08/154,800, filed 11/16/93, entitled "SYSTEM AND METHOD FOR DERIVING HEMODYNAMIC SIGNALS FROM A CARDIAC WALL MOTION SENSOR SIGNAL,” which is hereby incorporated by reference in its entirety.
  • the filtered signals are then provided as the input to a detector circuit 62 and the resulting output indicative of cardiac contractile activity is provided to the control logic and timing circuitry 56.
  • the detector circuit 62 could be a simple threshold detector or, as in the preferred embodiment, it could be a sample-and-hold circuit followed by an analog-to- digital converter and a comparator (not shown) , as is known in the art.
  • the control logic and timing circuitry 56 executes a program (the program code being stored in the memory 64) to perform demand pacing based on the mechanical contraction detector 58.
  • the control program of Fig. 3 illustrates a simplified flowchart to automatically calibrate the bandpass filter 60 (shown in Fig. 1) .
  • the bandpass filter 60 will be calibrated using an "evoked" contraction, based on the assumption that an intrinsic contraction has approximately the same response.
  • the calibration routine paces at the maximum amplitude which, in most cases will cause capture (barring, of course, any severe arrhythmia, e.g., fibrillation).
  • the advantage of using the evoked contraction is that the system will calibrate to signals representative of cardiac contractions caused by the application of the maximu amplitude stimulation pulse, and not, for example, body motion.
  • the calibration routing begins at start 100, which is followed by step 102, wherein the pulse generator 54 is adjusted to generate stimulation pulses having a predetermined maximum amplitude (e.g., 5 volts) .
  • the predetermined maximum amplitude is stored as a parameter in the memory 64.
  • the pulse generator 54 generates a stimulation pulse having the maximum amplitude at a rate which is programmed to be faster than the patient's intrinsic heart rate. Both the number of pulses and the pulse rate may be stored as parameters in the memory 64. Since the rate is set to be faster than the patient's natural rhythm, a contraction should be detected by the mechanical contraction detector 58 soon after the stimulation pulse is delivered.
  • the control logic and timing circuitry 56 tunes the preamplifier and bandpass filter 60 so that an expected excursion appears in the signal provided by the mechanical contraction detector 58 within a predetermined period of time following each maximum amplitude pacing pulse delivered at the step 104.
  • the control logic and timing circuitry 56 determines whether the calibration phase has been completed. Under most circumstances, sixty maximum amplitude stimulation pulses should be sufficient to properly calibrate the preamplifier and bandpass filter 60; however, this number can be stored as a parameter in the memory 64, and can be adjusted by the medical practitioner as needed. Until the calibration phase is completed, the program repeatedly loops back to the step 104, where the control logic and timing circuitry 56 causes the pulse generator 104 to generate another maximum amplitude stimulation pulse.
  • the mechanical contraction detector 58 can detect both evoked (stimulated) contractions and intrinsic (spontaneous) contractions.
  • the implantable cardiac stimulating device does not have to enter a blanking or a refractory period due to the amplifiers saturating in response to a stimulation pulse, as is done in EGM- based demand pacing.
  • the mechanical contraction-based demand pacemaker does not have to make special accommodations (e.g., separate sensing leads, circuitry to remove polarization or specialized sensing circuitry) in order to discern an evoked R-wave over the pulse-induced afterpotential.
  • the implantable cardiac stimulating device 50 may be capable of providing higher energy shock therapies to interrupt more severe cardiac arrhythmias.
  • cardioversion shocks may be administered to convert ventricular tachycardia (VT)
  • defibrillation shocks may be administered to convert ventricular fibrillation (VF) .
  • VF ventricular fibrillation
  • higher energy shock therapies are administered under the control of the control logic and timing circuitry 56.
  • the control logic and timing circuitry 56 may receive a signal indicative of whether the patient is experiencing a severe arrhythmia (e.g., VT or VF) based on the rate of the signals detected by the mechanical contraction detector 58, without relying on the IEGM signal.
  • a severe arrhythmia e.g., VT or VF
  • the control logic and timing circuitry 56 causes the high energy shock generator 70 (which may be conventional) to generate a therapeutic shock of an appropriate energy content to convert the particular type of arrhythmia detected. These higher energy shocks are generated and delivered to the patient's heart through at least one shocking lead 62.
  • the present invention can discriminate between arrhythmias based on the behavior of the mechanical contraction detector 58. Discrimination of cardiac arrhythmias base on, for example, cardiac wall motion sensor signals is also disclosed in the above- incorporated U.S. Patent Application No. 08/154,800.
  • the '800 patent application discloses a variety of hemodynamic signals that can be derived from a cardiac wall accelerometer sensor, including contractility, sympathetic tone, blood flow, fluid displacement and stroke volume.
  • the signals provided by the accelerometer-based cardiac wall motion sensors may be used by the control logic and timing circuitry 56 as a substitute for, or in combination with, the patient's IEGM for detecting hemodynamically stable and unstable tachycardias, in addition to detecting fibrillation.
  • the manner by which the implantable cardiac stimulating device 50 delivers pacing therapy and higher energy shock therapies is controlled by the control logic and timing circuitry 56 in accordance with parameters stored in a memory 64.
  • parameters are known in the art (e.g., escape interval, refractory period, cardioversion shock energy, defibrillation shock energy, etc.), and they may be programmed by a medical practitioner using a programming unit 72 that communicates with the control logic and timing circuitry 56 through a telemetry circuit 66.
  • control logic and timing circuitry 56 could be a microprocessor, a state machine or dedicated logic circuitry.
  • U.S. Patent Nos. 4,390,022 and 4,404,972 both disclose a microprocessor based implantable stimulation system, including high energy shocking systems.
  • U.S. Patent Nos. 4,712,555 and 3,595,242 illustrate state machines and dedicated circuitry, respectively, for controlling a demand pacemaker.
  • U.S. Patent Nos. 4,390,022; 4,404,972; 4,712,555; and 3,595,242 are all incorporated herein by reference in their entirety.
  • control logic and timing circuitry 56 evaluates the signal provided by the mechanical contraction detector 58 to control the implantable stimulation device may be fully appreciated by reference to the waveforms shown.
  • a surface ECG waveform 200, a ventricular electrogram (VTR EGM) waveform 300, and a cardiac wall motion signal 400 are shown synchronously in time.
  • the surface electrocardiogram (ECG) waveform 200 depicts two intrinsic beats, followed by two evoked, or stimulated, beats.
  • the intrinsic beats are comprised of a P-wave 202 and an R-wave 204.
  • the waveforms in Fig. 4 assume that an atrial stimulation lead has been implanted in the right atrium to provide dual-chamber pacing.
  • the evoked beats are comprised of an atrial stimulation pulse 220, followed by an evoked P-wave 222, and a ventricular stimulation pulse 224 followed by an evoked R-wave 226.
  • the ventricular electrogram waveform (VTR EGM) 300 is included for illustration purposes to show what an intracardiac electrogram sense amplifier of the prior art would see. It should be noted that P-waves are typically not seen on the ventricular electrogram.
  • the waveform 400 illustrates the output of the preferred mechanical contraction detector, i.e., a cardiac wall motion sensor.
  • a cardiac wall motion sensor located, for example, in the distal end of a ventricular lead, it may possible to detect both the atrial contraction (e.g., at excursion 402) and the ventricular contraction (e.g., at excursion 404). (This would have the advantage of permitting an atrial tracking mode with a single pass lead, thereby eliminating a lead in the atrium.)
  • the present invention could be adapted to include a mechanical contraction detector, such as the cardiac wall motion sensor, into an atrial lead.
  • the A-V delay is the desired conduction time between the atrium and the ventricle.
  • An R-wave which occurs during the A-V delay will inhibit a stimulation pulse in the ventricle.
  • a solid dot and the end of an interval is used to denote a sensed contraction (e.g., at 502) and an arrow denotes a timed-out event without sensing a cardiac contraction (e.g., 504).
  • the atrial escape interval 600 comprises a refractory period 602, 612, 622 (during which time the tissue is deemed incapable of stimulation) and an alert period 604, 614 or 624 (during which time the mechanical contraction detector is enabled) .
  • a P-wave 202 occurs during the alert period 604 of the atrial escape interval 600 (denoted by a solid dot at 606) and elicits an excursion 402 from the cardiac wall motion sensor, thereby initiating an A-V delay.
  • An R-wave 204 occurs during the A-V delay (denoted by the solid dot at 502) and elicits an excursion 404 from the cardiac wall motion sensor, thereby resetting the atrial escape interval 600 at 610.
  • the resetting of the atrial escape interval 600 is shown to occur at the very onset of the excursion 404, however it may be necessary to adjust the timing slightly based on the actual level of detection and the delay in detecting the excursion.
  • the atrial escape interval 600 times-out (denoted by the arrow at 608) without sensing another intrinsic P- wave.
  • a stimulation pulse 220 could be provided in the atrium which elicits the excursion 422 from the cardiac wall motion sensor, indicative of an evoked atrial contraction.
  • the A-V delay times-out (denoted by the arrow at excursion 504) without seeing an R-wave. Therefore, a stimulation pulse 224 is provided in the ventricle which captures the heart (at 226 and 326) and is detected by excursion 426 of the cardiac wall motion sensor.
  • excursion 404 also corresponds to the first cardiac heart sound
  • excursion 406 corresponds to the second heart sound
  • excursion 408 corresponds to the third heart sound.
  • the surface electrogram is shown in its relationship with other physiological signals that may be used for the mechanical contraction detector 58. It can be seen from Fig. 5 that any mechanical sensor which can detect the occurrence of a true ventricular contraction, such as, a sensor which can detect systole, the onset of systole (e.g., the period of isometric contraction) , or the period of ejection (e.g., the period when blood is ejected from the ventricles) would be suitable.
  • Closure of the A-V valve can be achieved by detecting the first heart sound using an acoustic sensor or with a cardiac motion sensor which detects cardiac wall accelerations, as described above, or by using an impedance measuring sensor to detect a change in impedance as the A-V valve closes (or when the aortic valve opens) . It can also be seen in Fig. 4 that a sensor which can detect a sudden increase in ventricular, atrial or aortic pressure could also be used to detect the onset of systole. Also, the peak atrial pressure could be used to detect the onset of systole.
  • any mechanical sensors which could detect the blood flow out of the ventricles also be a reliable detector of ventricular contractions.
  • blood flow sensors that may be used in the present invention would include stroke volume (e.g., impedance) , thermodilution, cardiac wall displacement, cardiac wall accelerations or cardiac wall velocity sensors. Measurement of stroke volume using impedance for purposes of modulating the rate of a pacemaker is known in the art, see for example U.S. Patent Nos.
  • Implantable pressure sensors for treating a malfunctioning heart are also well known in the art, see for example, (Cohen) U.S. Patent No. 4,899,751, which patent is incorporated herein by reference.
  • Piezoelectric pressure sensors for detecting the opening and closing of heart valves, stroke volume, and ejection time for purposes of modulating the rate of a pacemaker are also known in the art, see for example, U.S. Patent Nos. 4,600,017 (Schroeppel) or 4,802,481 (Schroeppel) which patents are hereby incorporated by reference.
  • Piezoresistive pressure transducers are also known for determining ventricular pressure, duration of contraction, ejection time, blood volume and the detection of the pulmonary valve opening and closing, 5 see for example U.S. Patent No. 4,730,619, which patent is incorporated herein by reference.
  • Isovolumic contraction time is also known to be used for modulating the rate of a pacemaker. Isovolumic contraction time is determined by detecting
  • Thermodilution sensors are well known in the
  • the first and second heart sounds 404 and 406, respectively, are available from the cardiac wall
  • a peak ventricular or aortic pressure sensor could also be used to detect the blood flow. In these embodiments, some compensation would be required in the timing circuitry 56 for the associated delay time
  • IEGM-based inhibition systems are overcome by the present invention.
  • Many of the advantages of the present invention are achieved through the use of a mechanical contraction detector which is responsive to contractile activity of the patient's heart.
  • the mechanical contraction detector provides a true indication of physical cardiac contractions, which may be processed to determine if a particular stimulation pulse or a naturally conducted cardiac signal evoked a cardiac contraction.

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

Abstract

Stimulateur cardiaque assurant une thérapie de stimulation 'à la demande' (54) commandé par un capteur physiologique (58) fournissant un signal représentatif des contractions mécaniques du coeur et comportant notamment des informations sur les différentes périodes du cycle cardiaque, de leur déclenchement et des pressions associées, ou des mouvements des valvules et de la tunique cardiaque, ou des bruits, ou des variations d'impédance, ou du débit du flux sanguin ou des signaux électriques, etc.
PCT/US1995/003642 1994-04-08 1995-03-27 Stimulateur cardiaque a commande physiologique et son procede WO1995027531A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU22296/95A AU2229695A (en) 1994-04-08 1995-03-27 Cardiac pacemaker with physiological control and method

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US22519494A 1994-04-08 1994-04-08
US08/225,194 1994-04-08

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Cited By (11)

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WO1998006454A1 (fr) * 1996-08-14 1998-02-19 Pacesetter Ab Stimulateur cardiaque
WO1999042169A1 (fr) * 1998-02-23 1999-08-26 Pacesetter Ab Electrode biocompatible, implantable, destinee a la stimulation electrique et mecanique des tissus
WO2007069962A1 (fr) * 2005-12-16 2007-06-21 St. Jude Medical Ab Dispositif medical implantable comprenant une fonctionnalite de commande d'une therapie
EP1049403A4 (fr) * 1998-01-20 2008-04-09 Cardiac Pacemakers Inc A Minne Controle a long terme des signaux d'acceleration pour l'optimisation des therapies par stimulation cardiaque
WO2009102613A3 (fr) * 2008-02-11 2009-11-05 Cardiac Pacemakers, Inc. Procédés de surveillance d'état hémodynamique pour une discrimination de rythme à l'intérieur du cœur
EP2196238A1 (fr) * 2008-12-12 2010-06-16 Ela Medical Dispositif médical actif du type prothèse cardiaque implantable, comprenant des moyens de stimulation auriculaire antitachycardique et de stimulation ventriculaire antibradycardique
WO2012005991A3 (fr) * 2010-06-29 2012-03-15 Cardiac Pacemakers, Inc. Dispositif de surveillance de vibrations mécaniques cardiaques utilisant des informations indicatives d'un mouvement de dérivation
EP2712549A1 (fr) 2012-10-01 2014-04-02 Sorin CRM SAS Dispositif d'évaluation de la désynchronisation ventriculaire temporelle
WO2016106305A1 (fr) * 2014-12-23 2016-06-30 Medtronic, Inc. Détection d'arythmie ventriculaire hémodynamiquement instable
WO2018064533A1 (fr) * 2016-09-29 2018-04-05 Medtronic, Inc. Suivi auriculaire dans un stimulateur ventriculaire intracardiaque
US10449366B2 (en) 2016-09-29 2019-10-22 Medtronic, Inc. Atrial tracking in an intracardiac ventricular pacemaker

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US4802481A (en) * 1984-07-19 1989-02-07 Cordis Leads, Inc. Apparatus for controlling pacing of a heart in response to changes in stroke volume
US4730619A (en) * 1985-04-11 1988-03-15 Telectronics, N.V. Apparatus and method for adjusting heart/pacer rate relative to ejection time to obtain a required cardiac output
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Cited By (36)

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Publication number Priority date Publication date Assignee Title
US6078835A (en) * 1996-08-14 2000-06-20 Pacesetter Ab Pacemaker wherein emission of stimulation pulses is controlled dependent on stretching of the ventricular wall
WO1998006454A1 (fr) * 1996-08-14 1998-02-19 Pacesetter Ab Stimulateur cardiaque
EP1049403A4 (fr) * 1998-01-20 2008-04-09 Cardiac Pacemakers Inc A Minne Controle a long terme des signaux d'acceleration pour l'optimisation des therapies par stimulation cardiaque
WO1999042169A1 (fr) * 1998-02-23 1999-08-26 Pacesetter Ab Electrode biocompatible, implantable, destinee a la stimulation electrique et mecanique des tissus
US6529777B1 (en) 1998-02-23 2003-03-04 Pacesetter Ab Electrode for tissue stimulation
US8060201B2 (en) 2005-12-16 2011-11-15 St. Jude Medical Ab Medical device
WO2007069962A1 (fr) * 2005-12-16 2007-06-21 St. Jude Medical Ab Dispositif medical implantable comprenant une fonctionnalite de commande d'une therapie
WO2009102613A3 (fr) * 2008-02-11 2009-11-05 Cardiac Pacemakers, Inc. Procédés de surveillance d'état hémodynamique pour une discrimination de rythme à l'intérieur du cœur
EP2196238A1 (fr) * 2008-12-12 2010-06-16 Ela Medical Dispositif médical actif du type prothèse cardiaque implantable, comprenant des moyens de stimulation auriculaire antitachycardique et de stimulation ventriculaire antibradycardique
US9084899B2 (en) 2008-12-12 2015-07-21 Sorin Crm S.A.S. Active implantable medical device having antitachycardia atrial and antibradycardia ventricular pacing
US8554319B2 (en) 2008-12-12 2013-10-08 Sorin Crm S.A.S. Active implantable medical device having antitachycardia atrial and antibradycardia ventricular pacing
WO2012005991A3 (fr) * 2010-06-29 2012-03-15 Cardiac Pacemakers, Inc. Dispositif de surveillance de vibrations mécaniques cardiaques utilisant des informations indicatives d'un mouvement de dérivation
WO2012005987A3 (fr) * 2010-06-29 2012-03-15 Cardiac Pacemakers, Inc. Discrimination de rythme à l'aide d'informations indicatives d'un mouvement de dérivation
US8478392B2 (en) 2010-06-29 2013-07-02 Cardiac Pacemakers, Inc. Rhythm discrimination using information indicative of lead motion
US8532770B2 (en) 2010-06-29 2013-09-10 Cardiac Pacemakers, Inc. Cardiac mechanical vibration monitor using information indicative of lead motion
US8649853B2 (en) 2010-06-29 2014-02-11 Cardiac Pacemakers, Inc. Cardiac function monitor using information indicative of lead motion
US8738111B2 (en) 2010-06-29 2014-05-27 Cardiac Pacemakers, Inc. Cardiac contraction detection using information indicative of lead motion
US9272149B2 (en) 2012-10-01 2016-03-01 Sorin Crm S.A.S. Device for assessment and therapy of temporal ventricular desynchronization
US9700727B2 (en) 2012-10-01 2017-07-11 Sorin Crm Sas Device for assessment and therapy of temporal ventricular desynchronization
EP2712549A1 (fr) 2012-10-01 2014-04-02 Sorin CRM SAS Dispositif d'évaluation de la désynchronisation ventriculaire temporelle
CN107206239B (zh) * 2014-12-23 2020-10-23 美敦力公司 血流动力学上不稳定的室性心律失常检测
WO2016106305A1 (fr) * 2014-12-23 2016-06-30 Medtronic, Inc. Détection d'arythmie ventriculaire hémodynamiquement instable
CN107206239A (zh) * 2014-12-23 2017-09-26 美敦力公司 血流动力学上不稳定的室性心律失常检测
US10052494B2 (en) 2014-12-23 2018-08-21 Medtronic, Inc. Hemodynamically unstable ventricular arrhythmia detection
US11103186B2 (en) 2014-12-23 2021-08-31 Medtronic, Inc. Hemodynamically unstable ventricular arrhythmia detection
US10350426B2 (en) 2014-12-23 2019-07-16 Medtronic, Inc. Hemodynamically unstable ventricular arrhythmia detection
WO2018064533A1 (fr) * 2016-09-29 2018-04-05 Medtronic, Inc. Suivi auriculaire dans un stimulateur ventriculaire intracardiaque
US10532212B2 (en) 2016-09-29 2020-01-14 Medtronic, Inc. Atrial tracking in an intracardiac ventricular pacemaker
US10449366B2 (en) 2016-09-29 2019-10-22 Medtronic, Inc. Atrial tracking in an intracardiac ventricular pacemaker
EP3858428A1 (fr) * 2016-09-29 2021-08-04 Medtronic, Inc. Suivi auriculaire dans un stimulateur ventriculaire intracardiaque
CN109789308A (zh) * 2016-09-29 2019-05-21 美敦力公司 心内心室起搏器中的心房跟踪
US11305126B2 (en) 2016-09-29 2022-04-19 Medtronic, Inc. Atrial tracking in an intracardiac ventricular pacemaker
US11357987B2 (en) 2016-09-29 2022-06-14 Medtronic, Inc. Atrial tracking in an intracardiac ventricular pacemaker
CN109789308B (zh) * 2016-09-29 2022-12-27 美敦力公司 心内心室起搏器中的心房跟踪
US12186569B2 (en) 2016-09-29 2025-01-07 Medtronic, Inc. Atrial tracking in an intracardiac ventricular pacemaker
US12214208B2 (en) 2016-09-29 2025-02-04 Medtronic, Inc. Atrial tracking in an intracardiac ventricular pacemaker

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