Patent US5385576A successfully refreshed from Google Patents.
US5385576A
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Method for detecting ventricular fibrillation and apparatus for detecting and treating ventricular fibrillation
Assignee: Pacesetter AB
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Filing: 1993-08-04
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Granted: 1995-01-31
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Expires: 2013-08-04
Abstract
Abstract In a method and apparatus for detecting ventricular fibrillation, a measured impedance signal, dependent on the blood volume in the heart, is evaluated, and ventricular fibrillation is assumed to be present if the level of the measured impedance signal falls below a predetermined threshold. This is based on the perception that as the heart fills with blood, given the presence of ventricular fibrillation, the level of the measured impedance signal will decrease. The apparatus also includes circuitry for treating the detected ventricular fibrillation.
Inventors
- 👤 Kjell Noren
- 👤 Pia Hagel
- 👤 Kurt Hoegnelid
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 10:37
CPC Classifications
A; A61; A61N; A61N1/00; A61N1/18; A61N1/32; A61N1/36; A61N1/362; A61N1/365; A61N1/36514; A61N1/36521; A61B; A61B5/00; A61B5/02; A61B5/026; A61B5/0295; A61N1/38; A61N1/39; A61N1/3956; A61N1/3962; A61N1/39622; A61N1/395
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
52 words
A method for detecting ventricular fibrillation comprising the steps of: evaluating a measured impedance signal obtained from a heart, dependent on blood volume in said heart; and identifying the occurrence of a drop in the level of said measured impedance signal below a prescribed threshold as indicating the presence of ventricular fibrillation.
Claim 2
Independent Claim
52 words
A method for detecting ventricular fibrillation comprising the steps of: evaluating a measured impedance signal obtained from a heart, dependent on blood volume in said heart; and identifying the occurrence of a drop in the level of said measured impedance signal below a prescribed threshold as indicating the presence of ventricular fibrillation.
Claim 3
Dependent Claim
38 words
A method as claimed in claim 1 comprising the additional step of: forming a chronological average of said level of said measured impedance signal; and setting said threshold at a value below said average by a predetermined amount.
Claim 4
Dependent Claim
49 words
A method as claimed in claim 1 comprising the additional steps of: monitoring the speed at which said level of said measured impedance signal drops; and using said speed at which said level of said measured impedance signal drops as a further indication of the presence of ventricular fibrillation.
Claim 5
Dependent Claim
34 words
A method as claimed in claim 1 comprising the additional steps of: monitoring the heartbeat rate of said heart; and using said heartbeat rate as an additional indication of the presence of ventricular fibrillation.
Claim 6
Independent Claim
99 words
An apparatus for detecting and treating ventricular fibrillation comprising: impedance measuring means for acquiring a measured impedance signal from a heart, dependent on the blood volume in said heart; evaluation means connected to said impedance measuring means for evaluating said measured impedance signal and for detecting a drop in the level of said measured impedance signal below a predetermined threshold, said drop being indicative of the presence of ventricular fibrillation; pulse generator means, activatable by said evaluation means, for generating electrical pulses; and electrode means, connected to said pulse generator means, for delivering said electrical pulses to said heart.
Claim 7
Independent Claim
99 words
An apparatus for detecting and treating ventricular fibrillation comprising: impedance measuring means for acquiring a measured impedance signal from a heart, dependent on the blood volume in said heart; evaluation means connected to said impedance measuring means for evaluating said measured impedance signal and for detecting a drop in the level of said measured impedance signal below a predetermined threshold, said drop being indicative of the presence of ventricular fibrillation; pulse generator means, activatable by said evaluation means, for generating electrical pulses; and electrode means, connected to said pulse generator means, for delivering said electrical pulses to said heart.
Claim 8
Dependent Claim
44 words
An apparatus as claimed in claim 5 wherein said evaluation means further includes averaging means for formulating a running chronological average of said level of said measured impedance signal and for setting said threshold to a value below said average by a predetermined amount.
Claim 9
Dependent Claim
70 words
An apparatus as claimed in claim 5 wherein said evaluation means includes further detector means for detecting the speed with which said level of said measured impedance signal drops, and means for logically combining output signals from said detector means and said further detector means for indicating the presence of ventricular fibrillation given the simultaneous presence of an output signal from said detector means and from said further detector means.
Claim 10
Dependent Claim
66 words
An apparatus as claimed in claim 5 further comprising: means for detecting heartbeats of said heart; further evaluation means for identifying a heartbeat rate from said heartbeats; and means for logically combining outputs of said evaluation means and said further evaluation means for indicating the presence of ventricular fibrillation given the simultaneous presence of an output from said evaluation means and from said further evaluation means.
Claim 11
Dependent Claim
39 words
An apparatus as claimed in claim 5 wherein said impedance measuring means comprises means for identifying said measured impedance signal from said electrical pulses generated by said pulse generator means and delivered to said heart via said electrode means.
Claim 12
Dependent Claim
34 words
An apparatus as claimed in claim 9 wherein said pulse generator means comprises means for generating pulses for identifying said measured impedance signal having a pulse amplitude below a stimulation threshold of said heart.
Claim 13
Dependent Claim
52 words
An apparatus as claimed in claim 9 wherein said pulse generator means comprises a stimulation pulse generator for generating pacemaker pulses and defibrillation pulse generator, activatable by said evaluation means, for generating defibrillation pulses, and wherein said electrical pulses generated by said stimulation pulse generator are supplied to said impedance measuring means.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1998-01-30 | 1998-08-01 | 1999-01-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-01-30 | 2002-08-01 | 2003-01-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-01-30 | 2006-08-01 | 2007-01-31 | $7700.00 | Window Closed / Lapsed |