Patent US5578064A successfully refreshed from Google Patents.
US5578064A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Rate responsive cardiac pacemaker with impedance sensing
Assignee: Intermedics Inc
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Filing: 1994-08-11
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Granted: 1996-11-26
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Expires: 2014-08-11
Abstract
Abstract An implantable, rate responsive pacemaker, sensitive to impedance changes in the heart as an indicator of cardiac stroke volume, wherein the baseline impedance is eliminated from the measurement of impedance. In one embodiment, an adaptively controlled, balanced bridge is utilized to eliminate the baseline. A Wein bridge is provided having a variable reactance whose impedance is controlled continuously. In another embodiment, an impedance measurement is modified by a signal conditioner providing an appropriate varying offset through the use of a sample and hold circuit and other signal modifying circuits prior to converting the impedance measurement to digital information. In a third embodiment, a sample and hold circuit may be used to provide digital information through an A to D converter to a microprocessor which directly controls a variable reactance. The end voltage of a pacing capacitor is used as an indication of a baseline impedance.
Inventors
- 👤 David Prutchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-10 01:06
CPC Classifications
A; A61; A61N; A61N1/00; A61N1/18; A61N1/32; A61N1/36; A61N1/362; A61N1/365; A61N1/368; A61N1/36514; A61N1/36521; A61B; A61B18/00; A61B2018/00636; A61B2018/00773; A61B2018/00875; Y; Y10; Y10S; Y10S128/00; Y10S128/901
Claims Analysis
Total Claims: 48
Claim 1
Independent Claim
130 words
A rate responsive cardiac pacemaker comprising pulse generator means for stimulating the heart of a patient to contract; means for controlling the rate of pulse generation by said pulse generator means; means for producing an electrical signal proportional to a changing impedance within the body of the patient, at least part of said changing impedance being caused by action of the heart; means for adaptively selecting a portion of said signal, said adaptively selected portion being related to non-cardiac factors in the body of the patient; means for attenuating said adaptively selected portion to produce an adaptively filtered signal; means for amplifying said adaptively filtered signal to produce an amplified adaptively filtered signal; and means for adjusting said rate controlling means as a function of said amplified adaptively filtered signal.
Claim 2
Dependent Claim
130 words
A rate responsive cardiac pacemaker comprising pulse generator means for stimulating the heart of a patient to contract; means for controlling the rate of pulse generation by said pulse generator means; means for producing an electrical signal proportional to a changing impedance within the body of the patient, at least part of said changing impedance being caused by action of the heart; means for adaptively selecting a portion of said signal, said adaptively selected portion being related to non-cardiac factors in the body of the patient; means for attenuating said adaptively selected portion to produce an adaptively filtered signal; means for amplifying said adaptively filtered signal to produce an amplified adaptively filtered signal; and means for adjusting said rate controlling means as a function of said amplified adaptively filtered signal.
Claim 3
Dependent Claim
38 words
The cardiac pacemaker according to claim 1 further comprising sensor means for detecting a non-impedance parameter correlated to physiologic need of said patient and means for adjusting said rate controlling means as a function of said detected parameter.
Claim 4
Dependent Claim
14 words
The cardiac pacemaker according to claim 2 wherein said sensor means is an accelerometer.
Claim 5
Dependent Claim
15 words
The cardiac pacemaker according to claim 2 wherein said sensor means is a temperature sensor.
Claim 6
Dependent Claim
22 words
The cardiac pacemaker according to claim 1 wherein said means for adaptively selecting a portion of said signal comprise a Wein bridge.
Claim 7
Dependent Claim
15 words
The cardiac pacemaker according to claim 5 wherein said Wein bridge comprises a variable reactance.
Claim 8
Dependent Claim
38 words
The cardiac pacemaker according to claim 6 further comprising sensor means for detecting a non-impedance parameter correlated to physiologic need of said patient and means for adjusting said rate controlling means as a function of said detected parameter.
Claim 9
Dependent Claim
14 words
The cardiac pacemaker according to claim 7 wherein said sensor means is an accelerometer.
Claim 10
Dependent Claim
15 words
The cardiac pacemaker according to claim 7 wherein said sensor means is a temperature sensor.
Claim 11
Dependent Claim
16 words
The cardiac pacemaker according to claim 6 wherein said variable reactance comprises a switched capacitor circuit.
Claim 12
Dependent Claim
16 words
The cardiac pacemaker according to claim 6 wherein said variable reactance comprises an operational transconductance amplifier.
Claim 13
Dependent Claim
33 words
The cardiac pacemaker according to claim 6 wherein said means for adaptively selecting a portion of said signal further comprise a differential amplifier connected in a feed back loop to said variable reactance.
Claim 14
Dependent Claim
25 words
The cardiac pacemaker according to claim 12 wherein said means for adjusting said rate controlling means comprise a microprocessor electrically connected to said differential amplifier.
Claim 15
Dependent Claim
17 words
The cardiac pacemaker according to claim 13 wherein said feed back loop comprises a band-pass filter circuit.
Claim 16
Dependent Claim
38 words
The cardiac pacemaker according to claim 14 further comprising sensor means for detecting a non-impedance parameter correlated to physiologic need of said patient and means for adjusting said rate controlling means as a function of said detected parameter.
Claim 17
Dependent Claim
14 words
The cardiac pacemaker according to claim 15 wherein said sensor means is an accelerometer.
Claim 18
Dependent Claim
15 words
The cardiac pacemaker according to claim 15 wherein said sensor means is a temperature sensor.
Claim 19
Dependent Claim
31 words
The cardiac pacemaker according to claim 1 wherein said means for adaptively selecting a portion of said signal comprise means for adjusting an impedance signal to off set said baseline impedance.
Claim 20
Dependent Claim
29 words
The cardiac pacemaker according to claim 18 wherein said means for adjusting said impedance signal comprise an off-set controlled operational amplifier and a feed-back loop for controlling said off-set.
Claim 21
Dependent Claim
25 words
The cardiac pacemaker according to claim 19 wherein said means for adjusting said rate controlling means comprise a microprocessor electrically connected to said operational amplifier.
Claim 22
Dependent Claim
38 words
The cardiac pacemaker according to claim 20 further comprising sensor means for detecting a non-impedance parameter correlated to physiologic need of said patient and means for adjusting said rate controlling means as a function of said detected parameter.
Claim 23
Dependent Claim
14 words
The cardiac pacemaker according to claim 21 wherein said sensor means is an accelerometer.
Claim 24
Dependent Claim
15 words
The cardiac pacemaker according to claim 21 wherein said sensor means is a temperature sensor.
Claim 25
Dependent Claim
18 words
The cardiac pacemaker according to claim 20 wherein said feed-back loop further comprises a sample and hold circuit.
Claim 26
Dependent Claim
16 words
The cardiac pacemaker according to claim 20 wherein said feed-back loop further comprises a band-pass filter.
Claim 27
Dependent Claim
18 words
The cardiac pacemaker according to claim 25 wherein said feed-back loop further comprises a sample and hold circuit.
Claim 28
Dependent Claim
39 words
The cardiac pacemaker according to claim 1 wherein said means for adaptively selecting a portion of said signal comprises means electrically connected to said pulse generator means for detecting charge remaining in said pulse generator means after a pulse.
Claim 29
Dependent Claim
19 words
The cardiac pacemaker according to claim 27 wherein said means for detecting charge comprise a sample and hold circuit.
Claim 30
Dependent Claim
39 words
The cardiac pacemaker according to claim 27 wherein said means for adjusting said rate controlling means comprise a Wein bridge having a variable reactance and means for controlling said variable reactance as a function of said detected remaining charge.
Claim 31
Dependent Claim
33 words
The cardiac pacemaker according to claim 29 wherein said means for adjusting said rate controlling means further comprise a differential amplifier connected to said Wein bridge for providing said amplified adaptively filtered signal.
Claim 32
Dependent Claim
38 words
The cardiac pacemaker according to claim 30 further comprising sensor means for detecting a non-impedance parameter correlated to physiologic need of said patient and means for adjusting said rate controlling means as a function of said detected parameter.
Claim 33
Dependent Claim
14 words
The cardiac pacemaker according to claim 31 wherein said sensor means is an accelerometer.
Claim 34
Dependent Claim
15 words
The cardiac pacemaker according to claim 31 wherein said sensor means is a temperature sensor.
Claim 35
Dependent Claim
38 words
The cardiac pacemaker according to claim 30 wherein said means for adjusting said rate controlling means further comprise a microprocessor for receiving said signal from said differential amplifier and providing a control signal to said pulse generator means.
Claim 36
Dependent Claim
38 words
The cardiac pacemaker according to claim 34 wherein said means for adjusting said rate controlling means further comprises impedance measurement means for processing said signal from said differential amplifier and for communicating a processed signal to said microprocessor.
Claim 37
Dependent Claim
18 words
The cardiac pacemaker according to claim 35 wherein said impedance measurement means comprise a sample and hold circuit.
Claim 38
Dependent Claim
16 words
The cardiac pacemaker according to claim 35 wherein said impedance measurement means comprise a band-pass filter.
Claim 39
Dependent Claim
18 words
The cardiac pacemaker according to claim 37 wherein said impedance measurement means comprise a sample and hold circuit.
Claim 40
Dependent Claim
127 words
A rate responsive cardiac pacemaker comprising pulse generator means for stimulating the heart of a patient to contract; means for controlling the rate of pulse generation by said pulse generator means; means for detecting a changing impedance within the body of the patient, at least part of said changing impedance being caused by action of the heart; means for isolating a baseline impedance from said changing impedance, said baseline impedance being related to non-cardiac factors in the body of the patient, said means for isolating said baseline impedance comprising an off-set controlled operational amplifier and a feed-back loop for controlling an off-set of said operational amplifier; means for adjusting said rate controlling means as a function of the difference of said changing impedance and said baseline impedance.
Claim 41
Dependent Claim
127 words
A rate responsive cardiac pacemaker comprising pulse generator means for stimulating the heart of a patient to contract; means for controlling the rate of pulse generation by said pulse generator means; means for detecting a changing impedance within the body of the patient, at least part of said changing impedance being caused by action of the heart; means for isolating a baseline impedance from said changing impedance, said baseline impedance being related to non-cardiac factors in the body of the patient, said means for isolating said baseline impedance comprising an off-set controlled operational amplifier and a feed-back loop for controlling an off-set of said operational amplifier; means for adjusting said rate controlling means as a function of the difference of said changing impedance and said baseline impedance.
Claim 42
Dependent Claim
25 words
The cardiac pacemaker according to claim 39 wherein said means for adjusting said rate controlling means comprise a microprocessor electrically connected to said operational amplifier.
Claim 43
Dependent Claim
38 words
The cardiac pacemaker according to claim 40 further comprising sensor means for detecting a non-impedance parameter correlated to physiologic need of said patient and means for adjusting said rate controlling means as a function of said detected parameter.
Claim 44
Dependent Claim
14 words
The cardiac pacemaker according to claim 41 wherein said sensor means is an accelerometer.
Claim 45
Dependent Claim
15 words
The cardiac pacemaker according to claim 41 wherein said sensor means is a temperature sensor.
Claim 46
Dependent Claim
18 words
The cardiac pacemaker according to claim 40 wherein said feed-back loop further comprises a sample and hold circuit.
Claim 47
Dependent Claim
16 words
The cardiac pacemaker according to claim 40 wherein said feed-back loop further comprises a band-pass filter.
Claim 48
Dependent Claim
18 words
The cardiac pacemaker according to claim 45 wherein said feed-back loop further comprises a sample and hold circuit.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-11-26 | 2000-05-27 | 2000-11-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-11-26 | 2004-05-27 | 2004-11-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-11-26 | 2008-05-27 | 2008-11-26 | $7700.00 | Window Closed / Lapsed |