Implantable stimulation device having means for optimizing current drain
First Claim
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1. An implantable pacemaker comprising:
- a battery;
pulse generating means for selectively generating electrical stimulation pulses at appropriate times for the purpose of depolarizing cardiac tissue, the electrical stimulation pulses being formed from electrical energy derived from the battery;
means for detecting capture at a patient'"'"'s stimulation threshold; and
pulse setting means, wherein the pulse setting means comprises;
means for determining a plurality of stimulation thresholds at a plurality of pulse widths at which capture is detected corresponding to a strength-duration curve;
means for adding a desired safety factor to the strength-duration curve to produce a plurality of pulse amplitude/pulse width combinations that would ensure capture at the desired safety factor;
means for determining a pacing current drain for each of the plurality of pulse amplitude/pulse width combinations that would ensure capture at the desired safety factor; and
means for selecting an optimal pulse amplitude/pulse width combination corresponding to a pulse amplitude/pulse width combination which ensures capture at the desired safety factor with the lowest pacing current drain.
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Abstract
An implantable pacemaker maintains a prescribed relationship between stimulation pulse amplitude and pulse width so as to provide an adequate safety factor above a stimulation threshold, while minimizing the current drain on the pacemaker battery. A series of stimulation pulse energies, each realized with a prescribed pulse amplitude and pulse width pair, are determined that may be used by the pacemaker as operating points. These operating points are numbered in order of increasing energy, and all adjustments of the pacing energy are made by selecting one of these operating points.
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Citations
33 Claims
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1. An implantable pacemaker comprising:
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a battery; pulse generating means for selectively generating electrical stimulation pulses at appropriate times for the purpose of depolarizing cardiac tissue, the electrical stimulation pulses being formed from electrical energy derived from the battery; means for detecting capture at a patient'"'"'s stimulation threshold; and pulse setting means, wherein the pulse setting means comprises; means for determining a plurality of stimulation thresholds at a plurality of pulse widths at which capture is detected corresponding to a strength-duration curve; means for adding a desired safety factor to the strength-duration curve to produce a plurality of pulse amplitude/pulse width combinations that would ensure capture at the desired safety factor; means for determining a pacing current drain for each of the plurality of pulse amplitude/pulse width combinations that would ensure capture at the desired safety factor; and means for selecting an optimal pulse amplitude/pulse width combination corresponding to a pulse amplitude/pulse width combination which ensures capture at the desired safety factor with the lowest pacing current drain. - View Dependent Claims (2, 3, 4, 5)
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6. An implantable pacemaker comprising:
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a battery; automatic capture detection means, powered by the battery, for detecting capture and for measuring stimulation threshold whenever capture is lost; stimulation means, powered by the battery, for generating electrical stimulation pulses of a prescribed pulse amplitude and width to cardiac tissue, the stimulation pulses being generated from electrical energy stored in the battery; and control means, powered by the battery, for defining a series of optimal pulse amplitude/pulse width combinations corresponding to a plurality of stimulation thresholds, wherein each of the pulse amplitude/pulse width combinations is calculated to minimize current drain on the battery as a function of a prescribed safety factor above a respective stimulation threshold; and selecting means, powered by the battery, for automatically selecting one of the series of optimal pulse amplitude/pulse combinations based on the measured stimulation threshold. - View Dependent Claims (7, 8, 9, 10)
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11. An implantable pacemaker comprising:
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a battery; sensing means, powered by the battery, for sensing a cardiac rhythm; control means, powered by the battery, for analyzing the sensed cardiac rhythm to determine if it is an acceptable rhythm as defined by a set of pre-defined parameters; stimulation means, powered by the battery and controlled by the control means, for generating electrical stimulation pulses of a prescribed pulse amplitude and width that are generated and delivered to cardiac tissue at appropriate times so as to maintain the acceptable rhythm defined by the set of pre-defined parameters, the stimulation pulses being generated from electrical energy stored in the battery; and pulse forming means for defining an optimal pulse amplitude/pulse width combination as a pulse amplitude/pulse width combination that maintains a minimal current drain on the battery, as a function of a first prescribed safety factor when the rhythm is acceptable and as a function of a second prescribed safety factor when the rhythm is not acceptable. - View Dependent Claims (12)
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13. An implantable pacemaker that includes:
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a battery; means for detecting stimulation threshold; pulse generating means, powered by the battery, for selectively generating electrical stimulation pulses, the electrical stimulation pulses having a pulse amplitude and pulse width that is defined by one of a plurality of operating points, each operating point being defined by a specific stimulation pulse amplitude and a specific stimulation pulse width, which pulse amplitude and pulse width have been calculated to provide a minimal pacing current drain on the battery as a function of a desired safety factor above the stimulation threshold. - View Dependent Claims (14)
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15. A pacing system for stimulating cardiac tissue with electrical stimulation pulses, the stimulation pulses having a pulse amplitude and width that assures that a given stimulation pulse, when delivered to the cardiac tissue, is above a stimulation threshold by a prescribed safety factor, the system comprising:
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(1) an implantable pacemaker including; (a) a battery, (b) control means, powered by the battery, for determining capture threshold, and (c) stimulation means, controlled by the control means, for generating electrical stimulation pulses of a prescribed pulse width and amplitude, and for delivering the electrical stimulation pulses to the cardiac tissue at appropriate times, the stimulation pulses being generated from electrical energy stored in the battery; and (2) an external programmer including; (a) means for selectively establishing a communication link with the implantable pacemaker, (b) means for defining, through the communication link, the prescribed pulse amplitude and width of the stimulation pulses to be generated by the stimulation means of the implantable pacemaker, the prescribed pulse amplitude and pulse width being calculated, as a function of a prescribed safety factor, to draw minimal energy from the battery of the implantable pacemaker. - View Dependent Claims (16, 17, 18)
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19. A method of operating an implantable pacemaker to use optimal stimulation pulse widths and stimulation pulse amplitudes as it performs its stimulation function, the optimal selection being made to minimize the pacemaker current drain while maximizing a safety factor of the pacemaker, the method comprising the steps of:
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(a) determining a stimulation threshold for a particular patient as a function of stimulation pulse width; (b) determining a stimulation pulse amplitude as a function of stimulation pulse width so as to achieve a given safety factor above the stimulation threshold; (c) computing a pacing current drain as a function of the stimulation pulse widths and amplitudes determined in step (b); (d) selecting a stimulation pulse amplitude and pulse width combination that provides a minimal pacing current drain as a function of pacing energy; and (e) programming the pacemaker to use the stimulation pulse amplitude and pulse width combination determined in step (d). - View Dependent Claims (20, 21, 22, 23, 24)
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25. A method of operating an implantable pacemaker to use optimal stimulation pulse widths and stimulation pulse amplitudes as it performs its stimulation function, the optimal selection being made to minimize the pacemaker current drain while maximizing a safety factor of the pacemaker, the method comprising the steps of:
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(a) determining a strength-duration curve for a particular patient; (b) determining an Iso-Safety Factor curve corresponding to a plurality of stimulation pulse amplitude/pulse width combinations which achieve a given safety factor above the strength-duration curve; (c) computing a pacing current drain as a function of the stimulation pulse widths and amplitudes determined in step (b); (d) selecting an optimal stimulation pulse amplitude and pulse width combination that provides a minimal pacing current drain as a function of pacing energy; and (e) programming the pacemaker to use the stimulation pulse amplitude and pulse width combination determined in step (d).
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26. A method of operating an implantable pacemaker, having a discharge circuit, to use optimal stimulation pulse widths and stimulation pulse amplitudes as it performs its stimulation function, the optimal selection being made to minimize the pacemaker current drain while maximizing a safety factor of the pacemaker, the method comprising the steps of:
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(a) determining a strength-duration curve for a particular patient; (b) determining an Iso-Safety Factor curve corresponding to a plurality of stimulation pulse amplitude/pulse width combinations which achieve a given safety factor above the strength-duration curve; (c) computing a pacing current drain as a function of the discharge circuit and stimulation pulse widths and amplitudes determined in step (b); (d) selecting an optimal stimulation pulse amplitude and pulse width combination that provides a minimal pacing current drain; and (e) programming the pacemaker to use the stimulation pulse amplitude and pulse width combination determined in step (d). - View Dependent Claims (27)
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28. An implantable pacemaker comprising:
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a battery; a discharge circuit, comprising a charge pump, output capacitor and pacing load; pulse generating means for selectively generating electrical stimulation pulses at appropriate times for the purpose of depolarizing cardiac tissue, the electrical stimulation pulses being formed from electrical energy derived from the battery; means for detecting capture at a patient'"'"'s stimulation threshold; and pulse setting means, wherein the pulse setting means comprises; means for determining a plurality of stimulation thresholds at a plurality of pulse widths at which capture is detected corresponding to a strength-duration curve; means for adding a desired safety factor to the strength-duration curve to produce a plurality of pulse amplitude/pulse width combinations that would ensure capture at the desired safety factor; means for determining a pacing current drain, as a function of the discharge circuit, for each of the plurality of pulse amplitude/pulse width combinations that would ensure capture at the desired safety factor, wherein said means includes consideration of the charge pump factor, capacitance of the output capacitor and pacing load; and means for selecting an optimal pulse amplitude/pulse width combination corresponding to a pulse amplitude/pulse width combination which ensures capture at the desired safety factor with the lowest pacing current drain.
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29. An implantable pacemaker that includes:
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a battery; means for detecting stimulation threshold; means for determining a stimulation efficacy as a function of the stimulation threshold and a desired safety factor; and pulse generating means, powered by the battery, for selectively generating electrical stimulation pulses, the electrical stimulation pulses having a pulse amplitude and pulse width that is defined by one of a plurality of operating points, each operating point providing a different stimulation efficacy and being defined by a specific stimulation pulse amplitude and pulse width combination that minimizes current drain for that stimulation efficacy. - View Dependent Claims (30)
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31. A pacing system for stimulating cardiac tissue with electrical stimulation pulses, the stimulation pulses having a pulse amplitude and width that assures that a given stimulation pulse, when delivered to the cardiac tissue, is above a stimulation threshold by a prescribed safety factor, the system comprising:
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(1) an implantable pacemaker including; (a) a battery, (b) control means, powered by the battery, for determining capture threshold, and (c) stimulation means, controlled by the control means, for generating electrical stimulation pulses of a prescribed pulse width and amplitude, and for delivering the electrical stimulation pulses to the cardiac tissue at appropriate times, the stimulation pulses being generated from electrical energy stored in the battery; and (2) an external programmer including; (a) means for selectively establishing a communication link with the implantable pacemaker, (b) means for defining, through the communication link, a series of stimulation pulse operating points of increasing stimulation efficacy, each operating point defining a stimulation pulse of increasing stimulation energy that is realized by a specific stimulation pulse amplitude in combination with a specific stimulation pulse width that draws minimal energy from the battery as a function of the prescribed safety factor. - View Dependent Claims (32, 33)
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Specification