Cardiac pacing responsive to multiple activity types
First Claim
1. A variable rate cardiac pacemaker adapted and configured to be implanted in a human patient, and adaptive in rate to different types of patient exercise such as walking and bicycling, comprising:
- sensor means adapted to respond to physical exercise by the patient for producing an electrical signal representative of the specific type of physical exercise being engaged in by the patient,pulse generator means for controllably generating pacing pulses in a range of rates adapted to stimulate the patient'"'"'s heart,memory means for storing different algorithms denoting heart rate as a function of respective ones of the different types of exercise for a healthy person with a normally functioning cardiovascular system, andcontrol means responsive to signals produced by said sensor means representative of different types of exercise engaged in by the patient for discriminating between specific types of exercise represented by the respective signals produced by said sensor means, including means having access to said different algorithms of said memory means and responsive to the type of exercise determined by the discrimination for selecting the algorithm corresponding to the type of exercise being engaged in by the patient, and including means to control the pacing rate of said pulse generating means according to the selected algorithm.
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Accused Products
Abstract
A variable rate implantable pacemaker responsive to patient exercise senses and distinguishes between distinct and different types of physical activity by the patient, and is programmed to respond by generating different response functions to control the pacing rate according to the specific type of physical activity detected. The response functions are algorithms, taken from the behavior of a healthy person with normally functioning cardiovascular system, of heart rates versus an appropriate parameter of a signal produced by a sensor carried by the patient, for the different types of activity requiring different algorithms, in which the parameter value varies in a predetermined way with exercise. The distinction between the different types of physical activity is derived by techniques including calculation of the absolute level of the sensor signal over time, calculation of the standard deviation relative to the mean of the parameter value of the sensor signal over time, performing pattern recognition by spectral analysis of the sensor signal and organizing different physical stress modes by comparing the various templates so observed with templates representing the different types of physical activity of interest, to determine the specific type of activity in which the patient is engaged, for use in controlling pacing rate.
86 Citations
30 Claims
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1. A variable rate cardiac pacemaker adapted and configured to be implanted in a human patient, and adaptive in rate to different types of patient exercise such as walking and bicycling, comprising:
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sensor means adapted to respond to physical exercise by the patient for producing an electrical signal representative of the specific type of physical exercise being engaged in by the patient, pulse generator means for controllably generating pacing pulses in a range of rates adapted to stimulate the patient'"'"'s heart, memory means for storing different algorithms denoting heart rate as a function of respective ones of the different types of exercise for a healthy person with a normally functioning cardiovascular system, and control means responsive to signals produced by said sensor means representative of different types of exercise engaged in by the patient for discriminating between specific types of exercise represented by the respective signals produced by said sensor means, including means having access to said different algorithms of said memory means and responsive to the type of exercise determined by the discrimination for selecting the algorithm corresponding to the type of exercise being engaged in by the patient, and including means to control the pacing rate of said pulse generating means according to the selected algorithm. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. In combination with an implantable rate responsive pacemaker having a pulse generator adapted to generate pulses for stimulating a patient'"'"'s heart at a variable pacing rate in response to a control signal derived from activity sensing means carried by the patient, the improvement comprising:
control means adapted to respond to each of a plurality of distinct and different activity signals generated by said activity sensing means representing different types of physical activity of the patient, as said control signal, for processing said control signal to detect the specific type of activity being engaged in by the patient and to adjust the pacing rate according to that specific type of activity, said control means including means for storing a plurality of different representations of heart rate as a function of acceleration signals arising from the respective types of physical activity for a healthy person with a normally functioning cardiovascular system, and means for continuously and automatically selecting a particular one of said representations according to the specific type of physical activity detected by said control means from which to adjust the pacing rate. - View Dependent Claims (18, 19, 20)
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21. A method of distinguishing distinct and different types of physical activity, such as walking and bicycling engaged in by a patient, from one another for the purpose of controlling the pacing rate of a variable rate pacemaker carried by the patient according to the specific type of physical activity in which the patient is engaged, which comprises:
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detecting one of an extrinsic parameter and an intrinsic parameter having a variable value representing activity of the patient, generating a control signal indicative of instantaneous value of said parameter, processing the control signal over time to derive therefrom the nature of the physical activity being engaged in by the patient, and controlling the pacing rate of the pacemaker according to the distinguished specific type of activity. - View Dependent Claims (22, 23)
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24. A method for discriminating true and consistent physiological signals such as a patient'"'"'s sinus rhythm having a variable value depending on patient exercise, from inconsistent or noise signals such as intermittent or otherwise faulty sensing, to control the pacing rate of a variable rate pacemaker carried by the patient in response to the variable value of the physiological signals, which comprises the steps of:
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sensing a physiological parameter having a variable value representing the extent of exercise engaged in by the patient, converting the sensed parameter to an output signal indicative of instantaneous value of said parameter and any noise components present thereon, processing the output signal by calculating variances, as the standard deviation, and the mean value of the output signal, and calculating the standard deviation relative to the mean value of the output signal over time to discriminate the true variations of the value of the physiological parameter from noise components of the output signal, and controlling the pacing rate of the pacemaker in response to the processed output signal to vary the pacing rate according to true variations of the value of the physiological parameter while suppressing any contribution attributable to noise components, and thereby, according to true patient exercise.
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25. Apparatus for discriminating true and consistent physiological signals such as a patient'"'"'s sinus rhythm having a variable value depending on patient exercise, from inconsistent or noise signals such as intermittent or otherwise faulty sensing, to control the pacing rate of a variable rate pacemaker carried by the patient in response to the variable value of the physiological signals, comprising:
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sensor means for sensing a physiological parameter having a variable value representing the extent of exercise engaged in by the patient, converting means responsive to the sensed parameter for converting the sensed parameter to an output signal indicative of instantaneous value of said parameter and any noise components present thereon, processing means responsive to the output signal for processing the output signal by calculating variances, as the standard deviation, and the mean value of the output signal, and calculating the standard deviation relative to the mean of the output signal over time to discriminate the true variations of the value of the physiological parameter from noise components of the output signal, and control means for controlling the pacing rate of the pacemaker in response to the processed output signal to vary the pacing rate according to true variations of the value of the physiological parameter while suppressing any contribution attributable to noise components.
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26. A cardiac pacemaker adapted to be carried by a patient and to generate an adjustable pacing rate that recognizes the type and tracks the strenuousness of activity of the patient, comprising:
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sensor means responsive to activity of the patient for producing an output representative thereof and including, as well, components attributable to sensed sources other than pure activity that tend to obscure the type and strenuousness of the activity; control means responsive to the sensor means output for developing a control signal representative of patient activity to adjust the pacing rate based on pure activity of the patient, including means for suppressing a contribution to pacing rate of said components attributable to sources other than pure activity according to the standard deviation relative to the mean of the output, and generator means responsive to said control signal for generating pulses at an adjustable pacing rate having an instantaneous value based on said pure activity of the patient. - View Dependent Claims (27, 28, 29)
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30. A method of adjusting the pacing rate of a cardiac pacemaker to be carried by a patient, according to the type and strenuousness of activity of the patient, including the steps of:
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sensing physical activity of the patient to produce an output representative of said physical activity, and including in said output, as well, components attributable to sensed sources other than pure physical activity that tend to obscure the type and strenuousness of the physical activity; generating pulses at an adjustable rate to set the heart rate of the patient, and adjusting the pacing rate based on the output component attributable to sensed pure activity of the patient and type of such activity to suppress a contribution to pacing rate of said components attributable to sources other than pure physical activity, by calculating the standard deviation and mean value of said output and dividing standard deviation by mean value over time.
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Specification