Patent EP0338364A2 successfully refreshed from Google Patents.
EP0338364A2
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EP
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Lead impedance scanning system for pacemakers
Assignee: St Jude Medical AB
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Filing: 1989-04-10
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Granted: —
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Expires: 2009-04-10
Abstract
Abstract A pacemaker lead analyzer for measuring impedance during standard operation of an implanted pacemaker. The analyzer makes separate measurements of lead impedance during each heart signal and each pacing pulse. A moving average of measured parameters is maintained and recurring deviations from the norms are noted in separate event counters for subsequent analysis of the noted events as possible indications of impending failure of an implanted lead.
Inventors
- 👤 Christer Dipl.-Ing. Ekwall
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 09:37
CPC Classifications
G; G01; G01R; G01R27/00; A; A61; A61N; A61N1/00; A61N1/18; A61N1/32; A61N1/36; A61N1/362; A61N1/37; A61N1/3706
Claims Analysis
Total Claims: 35
Claim 1
Independent Claim
60 words
A lead impedance scanning system for an implantable stimulation device comprising: means for making lead impedance measurements during operation of the device; means for comparing said impedance measurements with a preselected reference; and means responsive to the detection of measurement deviations which deviate from said reference by a predetermined amount for indicating the occurrence of a change in lead impedance.
Claim 2
Dependent Claim
60 words
A lead impedance scanning system for an implantable stimulation device comprising: means for making lead impedance measurements during operation of the device; means for comparing said impedance measurements with a preselected reference; and means responsive to the detection of measurement deviations which deviate from said reference by a predetermined amount for indicating the occurrence of a change in lead impedance.
Claim 3
Dependent Claim
34 words
The system of claim 1 wherein the device is a pacemaker and the means for making lead impedance measurements comprise means for measuring the energy delivered to a pacing lead during a stimulation pulse.
Claim 4
Dependent Claim
31 words
The system of claim 2 wherein said last-mentioned means include sampling means for sampling the energy level of the source of stimulation pulses before and after delivery of a stimulation pulse.
Claim 5
Dependent Claim
75 words
The system of claim 3 wherein sample voltages from the sampling means are used to provide a measurement of impedance in accordance with the following equations: R = -Tp/Cl 1n(1-dV/Vo)) where R respresents lead impedance, Tp is the stimulation pulse duration, Cl is the storage capacitor source for the stimulation pulse, Vo is the source voltage, and dV is the voltage difference between two voltage samples taken before and after delivery of a stimulation pulse.
Claim 6
Dependent Claim
26 words
The system of claim 3 further including means for developing a moving average of impedance measurements as said preselected reference for comparison with individual impedance measurements.
Claim 7
Dependent Claim
42 words
The system of claim 5 further including counter means for counting events corresponding to measurement deviations for subsequent analysis as an indication of a possibly defective lead, and means for advancing the counter means under predetermined conditions related to said measurement deviations.
Claim 8
Dependent Claim
35 words
The system of claim 6 wherein the means for advancing the counter means include means for establishing a counter advancing signal only upon the occurrence of a predetermined number of said measurement deviations in succession.
Claim 9
Dependent Claim
30 words
The system of claim 7 wherein said last-mentioned means comprises a three-bit shift register for developing a counter advancing signal only upon the occurrence of three measurement deviations in succession.
Claim 10
Dependent Claim
33 words
The system of claim 5 further including means for detecting the direction of change of impedance relative to said reference and for providing an indication of said detected direction of change of impedance.
Claim 11
Dependent Claim
23 words
The system of claim 1 wherein the means for making lead impedance measurements include means for measuring lead impedance from detected heart signals.
Claim 12
Dependent Claim
28 words
The system of claim 10 wherein the means for making lead impedance measurements further include means for developing signals corresponding to the slope of detected heart signal waveforms.
Claim 13
Dependent Claim
42 words
The system of claim 11 further including counter means for counting events corresponding to measurement deviations for subsequent analysis as an indication of a possibly defective lead, and means for advancing the counter means under predetermined conditions related to said measurement deviations.
Claim 14
Dependent Claim
35 words
The system of claim 11 wherein the comparing means comprise means for comparing said slope signals with a selected voltage reference and advancing the counter means only when a slope signal exceeds said voltage reference.
Claim 15
Dependent Claim
24 words
The system of claim 13 further including means for indicating the polarity of said slope signals to show the direction of change of impedance.
Claim 16
Dependent Claim
34 words
The system of claim 1 wherein the means for making lead impedance measurements include means for measuring impedance during the application of a stimulation pulse and means for measuring impedance from detected heart signals.
Claim 17
Dependent Claim
66 words
The system of claim 15 wherein the comparing means comprise a first comparator for comparing lead impedance measurements derived from energy delivered to the pacing lead during a stimulation pulse with a first reference corresponding to a moving average of such lead impedance measurements and a second comparator for comparing the slope of signal waveforms derived from sensed heart signals with a second predetermined voltage reference.
Claim 18
Dependent Claim
71 words
The system of claim 16 wherein the counter means comprise a first counter for storing a count corresponding to the occurrence of a predetermined number of said measurement deviations in succession which are derived from measurements made during the delivery of a stimulation pulse and a second counter for storing a count corresponding to the detection of rates of change of sensed heart signals in excess of a predetermined reference level.
Claim 19
Independent Claim
48 words
A method of discovering defective leads of an implantable stimulation device comprising the steps of: making lead impedance measurements during operation of the device; comparing said impedance measurements with a preselected reference; and noting the occurrence of measurement deviations which deviate from said reference by a predetermined amount.
Claim 20
Independent Claim
48 words
A method of discovering defective leads of an implantable stimulation device comprising the steps of: making lead impedance measurements during operation of the device; comparing said impedance measurements with a preselected reference; and noting the occurrence of measurement deviations which deviate from said reference by a predetermined amount.
Claim 21
Dependent Claim
41 words
The method of claim 18 further including the step of establishing a count of groups of measurement deviations for subsequent analysis as an indication of a defective lead; wherein a group is defined under predetermined conditions related to said measurement deviations.
Claim 22
Dependent Claim
31 words
The method of claim 18 further including the steps of detecting the polarity of said measurement deviations relative to said reference and providing an indication of direction of change of impedance.
Claim 23
Dependent Claim
29 words
The method of claim 18 wherein the step of making lead impedance measurements comprises measuring the energy delivered to a pacing lead of a pacemaker during a stimulation pulse.
Claim 24
Dependent Claim
25 words
The method of claim 21 wherein the energy measuring step includes sampling the source of stimulation pulses before and after delivery of a stimulation pulse.
Claim 25
Dependent Claim
74 words
The method of claim 22 wherein samples from the sampling step are used to provide a measurement of impedance in accordance with the following equation: R = -Tp/Cl 1n(1-dV/Vo)) where R represent a lead impedance, Tp is the stimulation pulse duration, Cl is the storage capacitor source for stimulation pulse, Vo is the source voltage, and dV is the voltage difference between two voltage samples taken before and after delivery of a stimulation pulse.
Claim 26
Dependent Claim
27 words
The method of claim 22 further including the step of developing a moving average of impedance measurements as said preselected reference for comparison with individual impedance measurements.
Claim 27
Dependent Claim
20 words
The method of claim 24 wherein a group is defined as a predetermined number of said measurement deviations in succession.
Claim 28
Dependent Claim
14 words
The method of claim 25 wherein said group comprises three measurement deviations in succession.
Claim 29
Dependent Claim
21 words
The method of claim 18 wherein the step of making lead impedance measurements includes measuring lead impedance from detected heart signals.
Claim 30
Dependent Claim
26 words
The method of claim 27 wherein the step of making lead impedance measurements further includes developing signals corresponding to the slope of detected heart signal waveforms.
Claim 31
Dependent Claim
34 words
The method of claim 28 wherein the step of comparing comprises comparing said slope signals with a selected voltage reference and counting a measurement deviation only when a slope signal exceeds said voltage reference.
Claim 32
Dependent Claim
31 words
The method of claim 19 wherein the step of making lead impedance measurements includes both measuring impedance during the application of a stimulation pulse and measuring impedance from detected heart signals.
Claim 33
Dependent Claim
59 words
The method of claim 30 wherein the step of comparing comprises both comparing lead impedance measurements derived from energy delivered to the lead during a stimulation pulse with a first reference corresponding to a moving average of such lead impedance measurements and comparing the slope of signal waveforms derived from sensed heart signals with a second predetermined voltage reference.
Claim 34
Dependent Claim
30 words
The method of claim 31 further including the step of providing an indication of the direction of change of lead impedance concurrently with providing an indication of impedance measurement deviations.
Claim 35
Dependent Claim
68 words
The method of claim 31 further including storing a count in a first counter corresponding to the occurrence of a predetermined number of said measurement deviations in succession which are derived from measurements made during the delivery of a stimulation pulse and storing a count in a second counter corresponding to the detection of rates of change of sensed heart signals in excess of a predetermined reference level.
References Cited (Backward Citations)
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