Physiologically responsive pacemaker and method of adjusting the pacing interval thereof
First Claim
1. A cardiac pacemaker for controlling the rate at which a heart beats as a function of physiological need, said heart beat rate defining a cardiac cycle during which atrial and ventricular events occur, said pacemaker comprising:
- means for generating an atrial stimulation pulse (A);
means for delivering said atrial stimulation pulse to an atrium of the heart in order to trigger atrial depolarization (P);
means for sensing the occurrence of said triggered atrial depolarization;
means for measuring the time interval between the generation of said atrial stimulation pulse and said triggered atrial depolarization, said atrial depolarization time interval being referred to as an A-P interval, said A-P interval varying as a function of physiological need; and
means for adjusting the pacemaker-controlled rate as a function of the measured A-P interval;
whereby the pacemaker-controlled rate is adjusted as a function of physiological need as sensed by measuring said depolarization time interval.
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Accused Products
Abstract
A pacemaker and physiological sensor for use therewith that allows the rate at which the pacemaker delivers electrical stimulation pulses to the heart, or the escape interval during which a natural heart event must occur before an electrical stimulation pulse is delivered, to be adjusted as needed in order to satisfy the body'"'"'s physiological needs. The sensor measures the depolarization time interval between an atrial stimulation pulse, A, and the responsive atrial or ventricle depolarization, P or R respectively, as an indication of the physiological demands placed on the heart. The time interval between a ventricular stimulation pulse, V, and the responsive ventricular depolarization, R, may also be measured and used as an indication of physiological need, and hence as an alternative criteria for rate control. Atrial depolarization is sensed by detecting a P-wave, and ventricular depolarization is preferably sensed by detecting an R-wave. A method of measuring A-P, A-R, or V-R intervals is used to ascertain if these intervals are increasing or decreasing. If, over several heart cycles or beats, an increase or decrease in these measurements is detected, the pacing interval set by the pacemaker is adjusted in an appropriate direction in order to adjust the heart stimulation rate accordingly.
505 Citations
47 Claims
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1. A cardiac pacemaker for controlling the rate at which a heart beats as a function of physiological need, said heart beat rate defining a cardiac cycle during which atrial and ventricular events occur, said pacemaker comprising:
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means for generating an atrial stimulation pulse (A); means for delivering said atrial stimulation pulse to an atrium of the heart in order to trigger atrial depolarization (P); means for sensing the occurrence of said triggered atrial depolarization; means for measuring the time interval between the generation of said atrial stimulation pulse and said triggered atrial depolarization, said atrial depolarization time interval being referred to as an A-P interval, said A-P interval varying as a function of physiological need; and means for adjusting the pacemaker-controlled rate as a function of the measured A-P interval; whereby the pacemaker-controlled rate is adjusted as a function of physiological need as sensed by measuring said depolarization time interval. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A cardiac pacemaker having means for generating a stimulation pulse, means for generating a pacing interval, means for controllably delivering said stimulation pulse to a heart at the conclusion of said pacing interval, and means for sensing the physiological need of the heart to be paced at a faster or slower rate, said physiological sensing means comprising:
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sensing means for sensing the occurrence of a cardiac depolarization event, referred to as X, which depolarization event follows the delivery of an atrial stimulation pulse, referred to as A, to the atrium of said heart; timing means for measuring the A-X time interval between the delivery of the stimulation pulse A to the atrium of the heart and the occurrence of the sensed cardiac depolarization event X, said A-X time interval thereby comprising the time it takes the heart to depolarize as measured from the time the stimulation pulse is delivered to the heart, said A-X time interval further representing a measured parameter that varies as a function of the physiological need of the heart to beat at a faster or slower rate; and means for controllably adjusting the pacing interval of the pacemaker as a function of the A-X time interval measured by said timing means, whereby stimulation pulses are controllably delivered to the heart at a rate that corresponds to the physiological need of the heart to beat at a faster or slower rate. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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15. A physiologically-controlled, rate-responsive, demand pacemaker having a pulse generator for selectively generating pacing pulses for delivery to a heart;
- distribution means for selectively controlling the delivery of the pacing pulses to the heart; and
physiological rate adjustment means for adjusting the rate at which the pacing pulses are delivered to the heart as a function of physiological need, said physiological rate adjusting means comprising;timing means for measuring the depolarization time interval between the generation of a given pacing pulse and the subsequent depolarization or contraction of said heart, said depolarization time interval being a parameter that changes as a function of physiological need; and means for automatically adjusting the rate at which the pacing pulses are delivered to the heart by said physiological rate adjustment means as a function of the measured depolarization time interval. - View Dependent Claims (16, 17, 18, 19, 20, 21)
- distribution means for selectively controlling the delivery of the pacing pulses to the heart; and
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22. A pacemaker having sensing and stimulating means coupled to the ventricle of a heart, said pacemaker comprising
means for generating a ventricular stimulation pulse and delivering said pulse to the ventricle through said stimulating means; -
means for measuring the depolarization time of the ventricle, said depolarization time comprising a V-R time interval that equals the time between the delivery of said ventricular stimulation pulse to the ventricle and the sensing, by said sensing means, of an R-wave; means for generating a control signal as a function of said measured V-R time interval; and means for adjusting a pacing rate of said pacemaker as a function of said control signal, said pacing rate controlling the rate a which said heart beats. - View Dependent Claims (23, 24, 25, 26, 27)
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28. A method for physiologically adjusting the pacing interval of a pacemaker, said pacemaker including means for generating an atrial pacing pulse, means for delivering the atrial pacing pulse to the atrium of a heart, and means for sensing the depolarization of the atrium in response to the delivered atrial pacing pulse, said method comprising the steps of:
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(a) generating an atrial pacing pulse and delivering said atrial pacing pulse to the atrium of the heart; (b) sensing the depolarization of the atrium resulting from the delivered atrial pacing pulse; (c) measuring the time interval between the generation of the atrial pacing pulse and the occurrence of the atrial depolarization, said time interval comprising an atrial depolarization time interval; and (d) using the atrial depolarization time interval as a control parameter to adjust the pacing interval of the pacemaker. - View Dependent Claims (29)
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30. A method for physiologically adjusting the pacing interval of a pacemaker, said pacemaker including means for generating a ventricular pacing pulse, means for delivering the ventricular pacing pulse to the ventricle of a heart, and means for sensing the depolarization of the ventricle in response to the delivered ventricular pacing pulse, said method comprising the steps of:
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(a) generating a ventricular pacing pulse and delivering said ventricular pacing pulse to the ventricle of the heart; (b) sensing the depolarization of the ventricle resulting from the delivered ventricular pacing pulse; (c) measuring the time interval between the generation of the ventricular pacing pulse and the occurrence of the ventricular depolarization, said time interval comprising a ventricular depolarization time interval; and (d) using the ventricular depolarization time interval as a control parameter to adjust the pacing interval of the pacemaker. - View Dependent Claims (31)
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32. A method for physiologically adjusting the pacing interval of a pacemaker, said pacemaker including means for generating an atrial pacing pulse, means for delivering the atrial pacing pulse so the atrium of the heart, means for sensing the depolarization of the atrium in response to the delivered atrial pacing pulse, and means for sensing the depolarization of the ventricle following the atrial depolarization, said method comprising the steps of:
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(a) generating an atrial pacing pulse and delivering said atrial pacing pulse to the atrium of the heart; (b) sensing the depolarization of the atrium resulting from the delivered atrial pacing pulse; (c) sensing the depolarization of the ventricle following the atrial depolarization sensed in step (b); (d) measuring the time interval between the generation of the atrial pacing pulse and the atrial depolarization sensed in step (b); (e) measuring the time interval between the generation of the atrial pacing pulse and the ventricular depolarization sensed in step (c); and (f) adjusting the pacing interval of the pacemaker as a function of a specified one of the time intervals measured in step (d) or (e). - View Dependent Claims (33, 34, 35)
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36. A method for physiologically adjusting the pacing interval of a pacemaker, said pacemaker including means for generating an atrial pacing pulse, means for delivering the atrial pacing pulse to the atrium of the heart, means for sensing the depolarization of the atrium in response to the delivered atrial pacing pulse, means for generating a ventricular pacing pulse, means for delivering the ventricular pacing pulse to the ventricle of the heart, and means for sensing the depolarization of the ventricle, said method comprising the steps of:
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(a) generating one of said atrial or ventricular pacing pulses and delivering said pacing pulse to the appropriate chamber of the heart; (b) sensing the depolarization of the heart chamber to which the pacing pulse is delivered; (c) measuring the time interval between the generation of the specified pacing pulse and a specified sensed depolarization, said time interval comprising a depolarization time interval; and (d) adjusting the pacing interval of the pacemaker as a function of the time interval measured in step (c). - View Dependent Claims (37, 38, 39)
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40. A method for measuring the atrial depolarization time of a heart, said atrial depolarization time being referred to as an A-P interval, said heart being stimulated by an atrial stimulation pulse delivered to the atrium of the heart from a pacemaker through an atrial lead, said atrial lead having first and second spaced-apart electrodes in contact with the atrium, said atrial lead providing electrical contact between an atrial stimulation pulse generator within said pacemaker and said first electrode, and said atrial lead further providing electrical contact between a P-wave sensing amplifier within said pacemaker and said second electrode, said measured A-P interval being usable by said pacemaker as a parameter indicative of physiological need, said method comprising the steps of:
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(a) stimulating the atrium with pulses generated by said atrial stimulation pulse generator; (b) monitoring the output of said P-wave sensing amplifier to detect the occurrence of a P-wave in response to the pulse provided in step (a); and (c) measuring the time interval between the occurrence of one of said pulses generated by said atrial stimulation pulse generator and the detection of a P-wave as sensed at the output of said P-wave sensing amplifier in step (b); the time interval measured in step (c) providing a measure of the atrial depolarization time, said atrial depolarization time providing, in turn, a relative measure of physiological need at the time the measurement is made. - View Dependent Claims (41, 42, 43)
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44. A method for measuring the ventricular depolarization time of a heart, said ventricular depolarization time being referred to as a V-R interval, said heart being stimulated by a ventricular stimulation pulse delivered to the ventricle of the heart from a pacemaker through a ventricular lead, said ventricular lead having first and second spaced-apart electrodes in contact with the ventricle, said ventricular lead providing electrical contact between a ventricular stimulation pulse generator within said pacemaker and said first electrode, and said ventricular lead further providing electrical contact between an R-wave sensing amplifier within said pacemaker and said second electrode, said measured V-R interval being usable by said pacemaker as a parameter indicative of physiological need, said method comprising the steps of:
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(a) stimulating the ventricle with pulses generated by said ventricular stimulation pulse generator; (b) monitoring the output of said R-wave sensing amplifier to detect the occurrence of an R-wave in response to the pulse provided in step (a); and (c) measuring the time interval between the occurrence of one of said pulses generated by said ventricular stimulation pulse generator and the detection of an R-wave as sensed at the output of said R-wave sensing amplifier in step (b);
the time interval measured in step (c) providing a measure of the ventricular depolarization time, said ventricular depolarization time providing, in turn, a relative measure of physiological need at the time the measurement is made. - View Dependent Claims (45, 46, 47)
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Specification