Pacemaker rate control using amplitude and frequency of activity signal
First Claim
1. An implantable variable rate pacemaker adaptive to patient exercise, comprisingmeans for detecting movements of the patient,means responsive to the detection of such movements for discriminating between those of the detected movements which arise from physical exercise by the patient and those of the detected movements which are unrelated to physical exercise,means responsive to such discrimination of the detected movements for generating an electrical signal representative of the detected movements which arise from physical exercise,means responsive to said electrical signal for sampling thereof in successive predetermined equal intervals of time to determine from each sample the maximum and minimum values of the amplitude of said signal in each interval, andmeans responsive to such determination of the maximum and minimum values of amplitude for ascertaining therefrom both the magnitude and the relative frequency of the detected movements which arise from physical exercise, to control the rate of said pacemaker according to both the ascertained magnitude and relative frequency.
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Accused Products
Abstract
A variable rate pacemaker responsive to patient exercise senses physical activity of the patient by motion detection and generates a corresponding electrical signal. The pacemaker circuitry detects maximum and minimum values of the amplitude of the electrical signal in equal intervals of time. These time intervals are selected to be shorter than the shortest possible interval between repetitions or of the cycle representing speed of the physical activity. Only one parameter is calculated, namely the difference in maximum and minimum amplitude within each time interval, to determine both the amplitude of the signal corresponding to intensity of the exercise and, indirectly, the frequency of the signal corresponding to exercise speed and repetition rate, for use in pacemaker rate control. In a specific embodiment, the data of successive time intervals is averaged into data blocks, and a first-in, first-out technique is applied to the averaged data blocks for use in the desired pacing rate control.
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Citations
31 Claims
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1. An implantable variable rate pacemaker adaptive to patient exercise, comprising
means for detecting movements of the patient, means responsive to the detection of such movements for discriminating between those of the detected movements which arise from physical exercise by the patient and those of the detected movements which are unrelated to physical exercise, means responsive to such discrimination of the detected movements for generating an electrical signal representative of the detected movements which arise from physical exercise, means responsive to said electrical signal for sampling thereof in successive predetermined equal intervals of time to determine from each sample the maximum and minimum values of the amplitude of said signal in each interval, and means responsive to such determination of the maximum and minimum values of amplitude for ascertaining therefrom both the magnitude and the relative frequency of the detected movements which arise from physical exercise, to control the rate of said pacemaker according to both the ascertained magnitude and relative frequency.
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7. A variable rate pacemaker responsive to patient exercise, comprising
motion sensing means for sensing physical activity of the patient and producing an electrical signal having amplitude maximum and minimum values representative of the repetitions and intensity of said physical activity, means for detecting said amplitude maximum and minimum values of said electrical signal in each interval of a train of predetermined equal intervals of time, and means for comparing the difference between the amplitude maximum and minimum values in different ones of said intervals of time to determine the relative repetitions of said physical activity in the compared intervals, for use in controlling the rate of said pacemaker.
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11. A process for controlling the heart rate of a patient by artificial stimulation of the heart at a variable rate according to patient exercise, comprising the steps of
detecting movements of the patient, discriminating between those of the detected movements arising from physical exercise by the patient and other detected movements of the patient, and scanning the detected movements arising from physical exercise in successive preselected equal intervals of time to assess from amplitude maxima and minima therein the relative rapidity of the physical exercise from one interval to the next, to adjust the stimulation rate according to that relative rapidity.
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15. A method for controlling the heart rate of a patient by artificial stimulation of the heart at a variable rate according to patient exercise, comprising the steps of
detecting movements of the patient representative of the exercise, and comparing the maximum and minimum magnitudes of the detected movements in successive equal time intervals to determine therefrom the relative frequency of the physical exercise in said time intervals, for use in controlling the stimulation rate.
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19. An implantable activity-sensing, rate adaptive pacemaker for use in a patient, comprising
means for detecting repetitive movements of the patient indicative of true exercise, and means responsive to detection of such repetitive movements for comparing the maximum and minimum amplitudes of the detected movements in each of successive equal intervals of time to determine therefrom the relative frequency of the repetitions over multiple ones of said time intervals, for use in controlling the stimulation rate of the pacemaker.
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24. In combination with a sensor for sensing a biological parameter of a patient indicative of the patient'"'"'s metabolic rate, a variable rate pacemaker adaptive to various hemodynamic conditions, comprising
means responsive to the sensing of said biological parameter for producing an electrical signal having amplitude and frequency content representative of changes in said biological parameter, and means responsive to detection of only the amplitude of said electrical signal for determining therefrom both relative amplitude and frequency of said signal representative of changes in said biological parameter for use in controlling the rate of said pacemaker.
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28. A method for controlling the heart rate of a patient by artificial stimulation of the heart at a variable rate according to various hemodynamic conditions, comprising the steps of
detecting a biological parameter of the patient indicative of the patient'"'"'s present metabolic state, converting the detected biological parameter to a signal having an amplitude and frequency content representative of changes in the biological parameter, determining the frequency of said signal from only the amplitude of said signal, and using both the amplitude of the signal and the frequency determined from the amplitude to control the patient'"'"'s heart rate.
Specification