US4880004A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Implantable cardiac stimulator with automatic gain control and bandpass filtering in feedback loop
Assignee: Intermedics Inc
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Filing: 1988-06-07
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Granted: 1989-11-14
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Expires: 2008-06-07
Abstract
Abstract An implantable cardiac stimulator for detecting and treating cardiac arrhythmias includes a sense amplifier responsive to sensed cardiac signals for detecting and distinguishing normal and abnormal cardiac activity within the sensed signals. The sense amplifier includes an automatic gain control amplifier, a filter and quad comparator having a pair of signal channels for processing the sensed signals according to different frequency bandpass characteristics to establish sensing thresholds, margins and signal gain. The sense amplifier has a feedback loop containing a microprocessor which implements preselected algorithms in conjunction with the outputs of the quad comparator to variably adjust the amplifier gain and to programmably control the sensing margin.
Inventors
- 👤 Ross G. Baker, Jr.
- 👤 Richard V. Calfee
- 👤 Edward A. Haluska
- 👤 Stephen J. Whistler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 20:28
CPC Classifications
A; A61; A61N; A61N1/00; A61N1/18; A61N1/32; A61N1/36; A61N1/362; A61N1/3621; A61N1/37; A61N1/3702; A61N1/3704; A61N1/3706; A61N1/38; A61N1/39; A61N1/3956; A61N1/3962; A61N1/39622
Claims Analysis
Total Claims: 42
Claim 1
Independent Claim
77 words
Apparatus for detecting cardiac arrhythmias by analyzing ECG signals produced by the heart, comprising: filter means forming dual signal paths having different bandpass characteristics for receiving said ECG signals, one of said signal paths constituting means for determining a sensing level for the ECG signals, and the other of the signal paths constituting feedback loop means for determining ECG signal gain and a sensing margin which is a function of the frequency content of the ECG signal.
Claim 2
Dependent Claim
77 words
Apparatus for detecting cardiac arrhythmias by analyzing ECG signals produced by the heart, comprising: filter means forming dual signal paths having different bandpass characteristics for receiving said ECG signals, one of said signal paths constituting means for determining a sensing level for the ECG signals, and the other of the signal paths constituting feedback loop means for determining ECG signal gain and a sensing margin which is a function of the frequency content of the ECG signal.
Claim 3
Dependent Claim
15 words
The invention according to claim 1, further comprising: a microprocessor in said feedback loop means.
Claim 4
Dependent Claim
19 words
The invention according to claim 1, further comprising: means in said feedback loop maintaining a user selectable sensing margin.
Claim 5
Dependent Claim
32 words
The invention according to claim 1, in which said feedback loop means includes means for maintaining said sensing margin at a ratio of peak signal amplitude-to-sensing threshold level of at least 2-to-1.
Claim 6
Dependent Claim
19 words
The invention according to claim 4, further including: means in said feedback loop means for programming said sensing margin.
Claim 7
Dependent Claim
41 words
The invention according to claim 1, in which said filter means forming dual signal paths includes means for adjusting bandpass characteristics of each said paths such that low frequencies are de-emphasized in the path that determines signal gain and sensing margin.
Claim 8
Dependent Claim
129 words
Implantable apparatus for detecting cardiac arrhythmias, comprising: electrode means for sensing electrical activity of a patient's heart, and processing means responsive to the sensed electrical activity for determining whether sensed events are indicative of arrhythmias, said processing means including target means establishing at least one reference level against which the amplitudes of predetermined sensed events are compared, gain control means controllably varying sensitivity of the processing means according to the amplitude of each sensed event relative to said at least one reference level, and comparison means responsive to said gain control means being adjusted in sensitivity in one direction immediately following an adjustment in the other direction for counting the number of times the sensed event crosses the reference level as an indication of the nature of the arrhythmia.
Claim 9
Dependent Claim
129 words
Implantable apparatus for detecting cardiac arrhythmias, comprising: electrode means for sensing electrical activity of a patient's heart, and processing means responsive to the sensed electrical activity for determining whether sensed events are indicative of arrhythmias, said processing means including target means establishing at least one reference level against which the amplitudes of predetermined sensed events are compared, gain control means controllably varying sensitivity of the processing means according to the amplitude of each sensed event relative to said at least one reference level, and comparison means responsive to said gain control means being adjusted in sensitivity in one direction immediately following an adjustment in the other direction for counting the number of times the sensed event crosses the reference level as an indication of the nature of the arrhythmia.
Claim 10
Dependent Claim
38 words
The invention according to claim 7, further comprising: means responsive to said processing means determining presence of an arrhythmia for delivering a therapy to the heart specifically for the treatment of that arrhythmia to restore normal sinus rhythm.
Claim 11
Dependent Claim
67 words
An implantable stimulator for detecting and treating cardiac arrhythmias, comprising: sensing means responsive to electrical activity of a heart and adapted to produce electrical signals representative of electrical activity of the heart, and signal processing means forming dual signal paths with different bandpass characteristics and responsive to the electrical signals for programmably controlling the sensing margin of the stimulator to components of said signals indicative of arrhythmia.
Claim 12
Dependent Claim
67 words
An implantable stimulator for detecting and treating cardiac arrhythmias, comprising: sensing means responsive to electrical activity of a heart and adapted to produce electrical signals representative of electrical activity of the heart, and signal processing means forming dual signal paths with different bandpass characteristics and responsive to the electrical signals for programmably controlling the sensing margin of the stimulator to components of said signals indicative of arrhythmia.
Claim 13
Dependent Claim
30 words
The implantable stimulator of claim 9, wherein said signal processing means comprises: amplifier means adapted to variably adjust the amplification of the electrical signals whereby detection of arrhythmias is enhanced.
Claim 14
Dependent Claim
37 words
The implantable stimulator of claim 10, wherein said signal processing means further comprises: a feedback loop for said amplifier means; and microprocessor means in said feedback loop adapted to control said amplifier means according to preselected algorithms.
Claim 15
Dependent Claim
28 words
The implantable stimulator of claim 11, wherein aid signal processing means further comprises: means for filtering said electrical signals passing only those signals in a predetermined frequency band.
Claim 16
Dependent Claim
65 words
Method of detecting cardiac arrhythmias, comprising the steps of: providing means for detecting electrical activity of a heart including both sinus rhythm and arrhythmias and producing electrical signals representative of that activity; and processing the electrical signals along dual signal paths having different bandpass characteristics while variably controlling sensitivity in response to selected components of said signals whereby detection of arrhythmias of interest is enhanced.
Claim 17
Dependent Claim
65 words
Method of detecting cardiac arrhythmias, comprising the steps of: providing means for detecting electrical activity of a heart including both sinus rhythm and arrhythmias and producing electrical signals representative of that activity; and processing the electrical signals along dual signal paths having different bandpass characteristics while variably controlling sensitivity in response to selected components of said signals whereby detection of arrhythmias of interest is enhanced.
Claim 18
Dependent Claim
76 words
An implantable defibrillator for automatically treating cardiac abnormalities, comprising: means for detecting electrical activity representing cardiac abnormalities of a heart; and means defining dual signal paths having different bandpass characteristics and responsive to the detected electrical activity for enhancing the frequency characteristics thereof and the amplitude of preselected frequency content indicative of designated cardiac abnormalities relative to predetermined threshold levels, to distinguish various abnormalities from one another including fibrillation, bradycardia, and tachycardia, to treat said abnormality.
Claim 19
Dependent Claim
76 words
An implantable defibrillator for automatically treating cardiac abnormalities, comprising: means for detecting electrical activity representing cardiac abnormalities of a heart; and means defining dual signal paths having different bandpass characteristics and responsive to the detected electrical activity for enhancing the frequency characteristics thereof and the amplitude of preselected frequency content indicative of designated cardiac abnormalities relative to predetermined threshold levels, to distinguish various abnormalities from one another including fibrillation, bradycardia, and tachycardia, to treat said abnormality.
Claim 20
Dependent Claim
95 words
An implantable cardiac stimulator for detecting cardiac arrhythmias, comprising: means for sensing cardiac signals; amplifier means responsive to sensed cardiac signals for detecting and distinguishing normal and abnormal cardiac activity therefrom, said amplifier means including; means defining dual signal paths for processing portions of the sensed signals representative of cardiac activity in two frequency bands each having different bandpass characteristics, and means in one of said signal paths for automatically adjusting the gain of the amplifier means according to the amplitude of the signals in one said frequency band to detect abnormal cardiac activity therefrom.
Claim 21
Dependent Claim
95 words
An implantable cardiac stimulator for detecting cardiac arrhythmias, comprising: means for sensing cardiac signals; amplifier means responsive to sensed cardiac signals for detecting and distinguishing normal and abnormal cardiac activity therefrom, said amplifier means including; means defining dual signal paths for processing portions of the sensed signals representative of cardiac activity in two frequency bands each having different bandpass characteristics, and means in one of said signal paths for automatically adjusting the gain of the amplifier means according to the amplitude of the signals in one said frequency band to detect abnormal cardiac activity therefrom.
Claim 22
Dependent Claim
25 words
The implantable cardiac stimulator of claim 15, further comprising: means responsive to abnormal cardiac activity for delivering a therapy appropriate to restore normal cardiac activity.
Claim 23
Dependent Claim
56 words
The implantable cardiac stimulator of claim 15, wherein said gain adjusting means comprises: means defining a feedback loop for said amplifier means, and microprocessor means in said feedback loop varying the gain of the amplifier means according to at least one predetermined algorithm selected to enhance the detection of a particular episode of abnormal cardiac activity.
Claim 24
Dependent Claim
19 words
The method of claim 13, wherein detection of two low signals in a row causes an increase in gain.
Claim 25
Dependent Claim
16 words
The method of claim 13, wherein detection of one high signal causes a decrease in gain.
Claim 26
Dependent Claim
19 words
The implantable cardiac stimulator of claim 15, wherein said amplifier means detects cardiac arrhythmias in the sensed cardiac signals.
Claim 27
Dependent Claim
29 words
The implantable cardiac stimulator of claim 20, wherein said amplifier means is adapted to distinguish bradycardia, tachycardia and fibrillation among the cardiac arrhythmias detected from the sensed cardiac signals.
Claim 28
Dependent Claim
33 words
The implantable cardiac stimulator of claim 15, wherein said amplifier means further comprises: means for establishing a sensing margin for the amplifier means as a ratio of peak signal amplitude to sensing threshold.
Claim 29
Dependent Claim
15 words
The implantable cardiac stimulator of claim 22, further comprising: means for programming said sensing margin.
Claim 30
Dependent Claim
91 words
An implantable cardiac stimulator for detecting cardiac arrhythmias by analyzing electrical signals produced by the heart, comprising: means for detecting electrical signals produced by the heart; and amplifier means responsive to the detected signals and having dual signal paths for said detected signals, each said signal path having different bandpass characteristics, means defining a feedback loop in one of said paths for automatically adjusting the gain of the amplifier means whereby gain and threshold relationships between said dual signal paths are controlled to produce variable sensing margins for different input waveforms.
Claim 31
Dependent Claim
91 words
An implantable cardiac stimulator for detecting cardiac arrhythmias by analyzing electrical signals produced by the heart, comprising: means for detecting electrical signals produced by the heart; and amplifier means responsive to the detected signals and having dual signal paths for said detected signals, each said signal path having different bandpass characteristics, means defining a feedback loop in one of said paths for automatically adjusting the gain of the amplifier means whereby gain and threshold relationships between said dual signal paths are controlled to produce variable sensing margins for different input waveforms.
Claim 32
Dependent Claim
24 words
An implantable cardiac stimulator according to claim 24, wherein an algorithm controlling gain requires sensing of two lows in a row to increase gain.
Claim 33
Dependent Claim
20 words
An implantable cardiac stimulator according to claim 24, wherein an algorithm controlling gain requires sensing one high to decrease gain.
Claim 34
Dependent Claim
25 words
An implantable cardiac stimulator according to claim 24, wherein an algorithm controlling gain requires a ratio of greater than 1to 1 to avoid T-wave sensing.
Claim 35
Dependent Claim
13 words
An implantable cardiac stimulator according to claim 27, wherein said ratio is 2:1.
Claim 36
Dependent Claim
32 words
An implantable cardiac stimulator according to claim 24, wherein an algorithm controlling gain avoids over-amplification when no valid signal is present, for purpose of noise immunity, and appropriate sensing when signals return.
Claim 37
Dependent Claim
18 words
An implantable cardiac stimulator according to claim 24, wherein an algorithm controls gain to optimize gain tracking responsiveness.
Claim 38
Dependent Claim
18 words
An implantable cardiac stimulator according to claim 24, wherein an algorithm controls gain to interact with arrhythmia detection.
Claim 39
Dependent Claim
76 words
An implantable defibrillator for automatically treating cardiac abnormalities, comprising: means for detecting electrical signals of a heart and distinguishing electrical signals representing cardiac abnormalities; and dual signal path means receiving said detected signals, each said path means having a different bandpass characteristic one said signal path means determining a sensing level for said signals and the other signal path having feedback loop means controlling gain thereby producing different sensing margins for different input electrical signal waveforms.
Claim 40
Dependent Claim
76 words
An implantable defibrillator for automatically treating cardiac abnormalities, comprising: means for detecting electrical signals of a heart and distinguishing electrical signals representing cardiac abnormalities; and dual signal path means receiving said detected signals, each said path means having a different bandpass characteristic one said signal path means determining a sensing level for said signals and the other signal path having feedback loop means controlling gain thereby producing different sensing margins for different input electrical signal waveforms.
Claim 41
Dependent Claim
19 words
An implantable defibrillator according to claim 32, wherein a high level margin is produced to detect erratic fibrillation signals.
Claim 42
Dependent Claim
23 words
An implantable defibrillator according to claim 32, wherein a low level margin is produced to detect QRS complexes while avoiding sensing of T-waves.
References Cited (Backward Citations)
US4406287A
Cited
US4523595A
Cited
US4554921A
Cited
US4766902A
Cited
US4768511A
Cited
US4774950A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-11-13 | 1993-05-15 | 1993-11-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-11-13 | 1997-05-15 | 1997-11-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-11-13 | 2001-05-15 | 2001-11-14 | $7700.00 | Window Closed / Lapsed |