Average amplitude controlled rate-responsive pacemaker having automatically adjustable control parameters
First Claim
1. A rate-responsive pacemaker comprising:
- pulse generating means for generating stimulating pulses;
control means for controlling the rate at which said pulse generating means generates said stimulating pulses;
sensor means for sensing a physiological parameter and for generating an electrical signal representative of said sensed physiological parameter; and
signal processing means for processing said electrical signal and for generating a control signal representative of the average amplitude of said electrical signal, said control signal being applied to said control means, and said control means being responsive at least in part to said control signal in controlling the rate at which said stimulating pulses are generated, wherein said signal processing means comprises;
rectifying amplifier means for amplifying and rectifying said electrical signal;
voltage controlled oscillator means coupled to the output of said rectifying amplifier means for generating an oscillator signal having a frequency that varies as a function of the signal output from said rectifying amplifier means; and
measurement means for measuring the frequency of said oscillator signal over a prescribed time interval, said frequency measurement comprising said control signal.
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Accused Products
Abstract
A device for use as a rate-responsive pacemaker is disclosed in which the pacing interval is controlled by the average amplitude of a raw signal generated by a suitable physiological sensor and processed by an average amplitude converter to generate an output average amplitude signal coupled to the pacemaker control circuits to adjust the pacing interval. The average amplitude converter may be a rectifying amplifier and an integrating circuit, a voltage controlled oscillator whose frequency is measured over a suitable time interval using a time interval generator and a counter with the output of the counter being used by the control circuits of the pacemaker to vary its pacing interval, or means for measuring average amplitude of the raw signal and storing that measurement in memory and periodically processing it to alter the transfer characteristics of the rate-responsive pacemaker.
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Citations
23 Claims
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1. A rate-responsive pacemaker comprising:
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pulse generating means for generating stimulating pulses; control means for controlling the rate at which said pulse generating means generates said stimulating pulses; sensor means for sensing a physiological parameter and for generating an electrical signal representative of said sensed physiological parameter; and signal processing means for processing said electrical signal and for generating a control signal representative of the average amplitude of said electrical signal, said control signal being applied to said control means, and said control means being responsive at least in part to said control signal in controlling the rate at which said stimulating pulses are generated, wherein said signal processing means comprises; rectifying amplifier means for amplifying and rectifying said electrical signal; voltage controlled oscillator means coupled to the output of said rectifying amplifier means for generating an oscillator signal having a frequency that varies as a function of the signal output from said rectifying amplifier means; and measurement means for measuring the frequency of said oscillator signal over a prescribed time interval, said frequency measurement comprising said control signal. - View Dependent Claims (2, 3)
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4. A rate-responsive pacemaker comprising:
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pulse generating means for generating stimulating pulses; control means for controlling the rate at which said pulse generating means generates said stimulating pulses; sensor means for sensing a physiological parameter and for generating an electrical signal representative of said sensed physiological parameter; and signal processing means for processing said electrical signal and for generating a control signal representative of the average amplitude of said electrical signal, said control signal being applied to said control means, and said control means being responsive at least in part to said control signal in controlling the rate at which said stimulating pulses are generated, wherein said signal processing means comprises; rectifier means for rectifying said electrical signal generated by said sensor means; and integrating means for integrating the rectified signal obtained from said rectifier means and for generating an output signal representative of the integration of said rectified signal, said output signal comprising the control signal that is applied to said control means. - View Dependent Claims (5, 6)
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7. In a rate-responsive pacemaker adapted to provide stimulating pulses to a heart at a controlled rate, which controlled rate includes the ability to vary an escape interval when said pacemaker is operating in a demand mode of operation, and which controlled rate is controlled at least in part by a control signal, a signal processing system for generating said control signal as a function of a raw signal outputted from a physiological sensor, said raw signal having an average amplitude indicative of a physiological parameter sensed by said physiological sensor, said signal processing system comprising:
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amplifier means for amplifying said raw signal and for producing an amplified raw signal, said amplified raw signal having an average amplitude associated therewith proportional to the average amplitude of said raw signal; and control signal generating means responsive to said amplified raw signal for generating said control signal as a function of the average amplitude of said amplified raw signal. - View Dependent Claims (8, 9, 10, 11)
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12. A method of processing a raw signal obtained from a physiological sensor used with a rate-responsive pacemaker to produce a control signal, said control signal being used by said pacemaker to control the pacing interval thereof, said method comprising the steps of:
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(a) determining the amount of average amplitude of said raw signal; and (b) generating said control signal as a function of the average amplitude determined in step (a). - View Dependent Claims (13)
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14. In a rate-responsive pacemaker adapted to provide stimulating pulses to a heart at a controlled rate on demand as a function of sensed physiological need, and wherein the controlled rate is determined by a prescribed transfer function that relates the sensed physiological need to the pacing rate, an adaptive system for automatically altering the prescribed transfer function comprising:
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means for sensing a physiological need of a user of said rate-responsive pacemaker at prescribed intervals, and for generating a physiological signal indicative of such need during said prescibed intervals, each physiological signal thus generated having an average amplitude associated therewith; pulse generating means for producing stimulating pulses on demand at a rate controlled by a rate control signal; control means for generating said rate control signal during a given interval as a function of the average amplitude of the physiological signal corresponding to said given interval, the relationship between said rate control signal and the average amplitude of said physiological signal comprising said prescribed transfer function, said prescribed transfer function being alterable as a function of at least one transfer-function control parameter; memory means for selectively storing said physiological signals; trend processing means for identifying trends in the physiological signals stored in said memory means over a plurality of said prescribed intervals; and means for altering said at least one transfer-function control parameter as a function of the trends identified by said trend processing means; whereby the prescribed transfer function of said rate-responsive pacemaker is automatically altered as a function of identified trends in the physiological needs of said user. - View Dependent Claims (15, 16, 17)
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18. A rate-responsive pacemaker comprising:
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stimulating means for selectively generating stimulating pulses on demand in response to a control signal; first sensing means for sensing natural cardiac activity; second sensing means for sensing physiological need, said second sensing means comprising; transducer means for converting physical forces applied thereto to an electrical output signal, and signal processing means for determining the average amplitude of said electrical output signal and for generating an average amplitude signal representative of said average amplitude; and control means responsive to said first and second sensing means for generating said control signal as a function of sensed cardiac activity and said average amplitude signal in accordance with a prescribed transfer function, and for identifying trends in cardiac activity and physiological need sensed over a prescribed time period, and for altering said prescribed transfer function in response to the identification of said trends. - View Dependent Claims (19, 23)
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20. A rate-responsive pacemaker comprising:
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stimulating means for selectively generating stimulating pulses on demand in response to a control signal; sensing means for sensing physiological need, said sensing means including means for generating a raw signal having an average amplitude indicative of physiological need; and control means responsive to said sensing means for generating said control signal as a function of a prescribed transfer function between said control signal and the average amplitude of said raw signal, said control means including; trend identification means for identifying trends in physiological need sensed over a prescribed time period, and control signal altering means for altering the prescribed transfer function in response to the identification of said trends by said trend identification means.
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21. A rate-responsive pacemaker including means for generating stimulating pulses on demand as a function of sensed physiological need, the improvement comprising:
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sensor means for generating a raw signal, said raw signal having an average amplitude that varies as a function of at least one physiological parameter; and processing means for determining the average amplitude of said raw signal, said average amplitude being used thereafter by said rate-responsive pacemaker as an indicator of physiological need. - View Dependent Claims (22)
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Specification