Rate responsive cardiac pacemaker
First Claim
1. An implantable variable rate pacemaker adaptive to patient exercise, comprisingmeans for detecting movements of the patient,means responsive to the detected movements for discriminating between those of the detected movements which are related to physical exercise by the patient and those of the detected movements which are not related to physical exercise by the patient,means for sampling the detected movements related to physical exercise in successive equal intervals of time to determine whether the physical exercise is more vigorous or less vigorous than was determined for prior time intervals, andmeans responsive to the determination for adjusting the rate of said pacemaker accordingly.
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Accused Products
Abstract
An activity-based variable rate pacemaker senses motion in a preselected low frequency range to detect physical activity of the patient and produce an electrical signal having amplitude maxima and minima representative of the speed and intensity of the physical activity. The electrical signal is selectively limited to appreciable amplitude values for detected physical activity which is related to true physical exercise by the patient, in contrast to detected physical activity which is related to internal and external disturbances on the patient. The amplitude maxima and minima of the selectively limited signal are detected in successive equal intervals of time, the results obtained for consecutive blocks of time each containing the same number of successive equal intervals of time are compared to determine whether the physical exercise is more vigorous or less vigorous than that determined for a predetermined number of immediately preceding blocks, and the pacing rate is adjusted accordingly. The amplitude maxima and minima are sampled at a relatively low rate to conserve energy, and the time intervals are about 300 milliseconds each.
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Citations
16 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 detected movements for discriminating between those of the detected movements which are related to physical exercise by the patient and those of the detected movements which are not related to physical exercise by the patient, means for sampling the detected movements related to physical exercise in successive equal intervals of time to determine whether the physical exercise is more vigorous or less vigorous than was determined for prior time intervals, and means responsive to the determination for adjusting the rate of said pacemaker accordingly.
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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 speed and intensity of said physical activity, means for selectively limiting said electrical signal to appreciable amplitude values for the detected physical activity which is related to true physical exercise by the patient in contrast to the detected physical activity which is related to internal and external disturbances on the patient not representative of true physical exercise, means for detecting the amplitude maximum and minimum values of said selectively limited electrical signal in successive equal intervals of time, means for comparing the detected values for consecutive blocks of time each containing the same number of successive equal intervals of time to determine from the comparison whether the physical exercise represented by the detected values for the most recent block is more vigorous or less vigorous than the physical exercise represented by the detected values for the immediately preceding block, and means for changing the rate of said pacemaker according to the determination of whether the physical exercise is more vigorous or less vigorous with time.
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15. 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 which are indicative of physical exercise by the patient and those of the detected movements which are not related to physical exercise by the patient, sampling the detected movements which are indicative of physical exercise in sets of successive equal intervals of time, comparing the samples from the most recent sampled set of time intervals with the samples from the immediately preceding sampled set of time intervals to determine whether the physical exercise by the patient is more vigorous or less vigorous with time, and changing the rate of artificial stimulation of the patient'"'"'s heart to reflect changes in the vigorousness of the physical exercise determined from the comparison.
Specification