Cardiac pacing system with improved end-of-life detector
First Claim
1. A pacemaker having a battery, pacemaker circuitry for carrying out pacing functions, and an energy consumption detector, said detector comprising(a) accumulating means for accumulating a signal representative of the integral of pacemaker circuitry current over the time since it last started to accumulate said signal;
- (b) readout means for reading out said accumulated signal when it reaches a predetermined threshold and for developing therefrom a measure of battery expenditure over said time;
(c) said readout means having means for zeroing out said accumulated signal so that said accumulating means repeats the function of accumulating a said representative signal from the time of said zeroing out until the time of the next readout; and
(d) means for accumulating signals which have been read out and for storing a signal representative of overall battery expenditure.
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Accused Products
Abstract
A pacemaker is provided having an improved circuit for obtaining a measure of battery end-of-life. The EOL detector includes an input stage with a current mirror output providing a current which is proportional to the current being consumed by the pacemaker circuitry, and thus being expended by the battery. The proportional current is directed to charge a capacitor, which is periodically discharged at a constant current, following which the battery goes through repeated cycles of charging and discharging. A measuring circuit measures the time of capacitor discharge, thereby providing a measure of battery energy discharge during the interval that the capacitor was charging. The interval counts are accumulated to provide an overall count representative of battery expenditure, and thus of pacemaker EOL.
88 Citations
17 Claims
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1. A pacemaker having a battery, pacemaker circuitry for carrying out pacing functions, and an energy consumption detector, said detector comprising
(a) accumulating means for accumulating a signal representative of the integral of pacemaker circuitry current over the time since it last started to accumulate said signal; -
(b) readout means for reading out said accumulated signal when it reaches a predetermined threshold and for developing therefrom a measure of battery expenditure over said time; (c) said readout means having means for zeroing out said accumulated signal so that said accumulating means repeats the function of accumulating a said representative signal from the time of said zeroing out until the time of the next readout; and (d) means for accumulating signals which have been read out and for storing a signal representative of overall battery expenditure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An implantable pacemaker system having a battery for the supply of energy, a pacing subsystem connected to said battery for generating and delivering pacing pulses to a patient, and a circuit for obtaining a measure of battery discharge, said circuit comprising,
sense means for generating a current proportional to the current through said pacemaker subsystem; -
a capacitor connected to receive said proportional current; discharge means for cyclically discharging said capacitor; measure means for determining a measure of the energy discharged from said capacitor each time it is discharged and for generating signals representative of said measure, said signals thus being representative of battery discharge during each charging of said capacitor; and accumulating means for accumulating said representative signals, thereby providing a measure of overall battery discharge. - View Dependent Claims (10, 11, 12)
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13. An implantable pacemaker system having a battery for the supply of energy, a pacing subsystem powered by said battery for generating and delivering pacing pulses to a patient, and a circuit for obtaining a measure of the energy discharge of said battery, said circuit comprising:
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a) a sense circuit for sensing current through said pacemaker circuitry, a capacitor and a charging circuit connecting said sense circuit and said capacitor for charging said capacitor with a charge which is a measure of the integral of said sensed current over time, and thus of battery energy discharge while said capacitor is charging; b) discharge means for discharging said capacitor at a fixed discharge current, whereby the time of discharge is a measure of said integral and independent of the value of said capacitor; and c) a measuring circuit for developing a representative signal representative of said discharge time and thus representative of said integral. - View Dependent Claims (14)
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15. A device having a battery for the supply of energy, a subsystem connected to said battery for performing predetermined functions, and a circuit for obtaining a measure of battery discharge, said circuit comprising,
sense means for generating a current proportional to the current through said subsystem; -
a capacitor connected to receive said proportional current; discharge means for cyclically discharging said capacitor at a constant discharge current; signal means for generating signals representative of the energy discharged from said capacitor each time it is discharged, said signals thus being representative of battery discharge during each charging of said capacitor; and accumulating means for accumulating said representative signals, thereby providing a measure of overall battery discharge. - View Dependent Claims (16, 17)
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Specification