US5540723A
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US
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Method and apparatus for delivering an optimum shock duration in treating cardiac arrhythmias
Assignee: Cardiac Pacemakers Inc
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Filing: 1993-10-06
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Granted: 1996-07-30
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Expires: 2013-10-06
Abstract
Abstract The present invention provides apparatus and methods for delivering an optimum electrical shock in treating cardiac arrhythmias. The invention comprises apparatus for producing an electrical waveform signal at least at two electrodes. The voltage or current of the signal is then detected to determine the signal time constant. The signal time constant is then used in conjunction with a model time constant to determine when the peak amplitude is reached. The waveform is then interrupted when the peak amplitude is reached. Also provided are methods of selecting a cardiac defibrillator by measuring the impedance of implanted electrodes and then selecting a defibrillator having a capacitor which provides an RC time constant equal to that of a model time constant.
Inventors
- 👤 Raymond E. Ideker
- 👤 Gregory P. Walcott
- 👤 Stephen J. Hahn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 17:06
CPC Classifications
A; A61; A61N; A61N1/00; A61N1/18; A61N1/32; A61N1/38; A61N1/39; A61N1/3925; A61N1/3937
Claims Analysis
Total Claims: 33
Claim 1
Independent Claim
134 words
A cardiac arrythmia treatment apparatus, comprising: (a) shock means for delivering a waveform signal to a pair of electrodes; (b) detecting means for detecting an electrical characteristic of said pair of electrodes during delivery of said waveform signal wherein said electrical characteristic is selected from the group consisting of the voltage across said electrodes and the current through at least one of said electrodes; (c) time constant calculating means for determining a waveform time constant (t s ) from said electrical characteristic; (d) storage means for storing a model time constant (t m ); (e) membrane voltage calculating means for determining when a peak membrane voltage is reached from said waveform time constant and said model time constant; and (f) switch means for interrupting said waveform signal when said peak membrane voltage is reached.
Claim 2
Dependent Claim
134 words
A cardiac arrythmia treatment apparatus, comprising: (a) shock means for delivering a waveform signal to a pair of electrodes; (b) detecting means for detecting an electrical characteristic of said pair of electrodes during delivery of said waveform signal wherein said electrical characteristic is selected from the group consisting of the voltage across said electrodes and the current through at least one of said electrodes; (c) time constant calculating means for determining a waveform time constant (t s ) from said electrical characteristic; (d) storage means for storing a model time constant (t m ); (e) membrane voltage calculating means for determining when a peak membrane voltage is reached from said waveform time constant and said model time constant; and (f) switch means for interrupting said waveform signal when said peak membrane voltage is reached.
Claim 3
Dependent Claim
59 words
A cardiac arrythmia treatment apparatus according to claim 1, wherein said apparatus is a biphasic apparatus, said waveform signal is a first waveform signal, and said apparatus further comprising reverse polarity shock means for delivering a second waveform signal after said first waveform signal, with said second waveform signal having a polarity opposite that of said first waveform signal.
Claim 4
Dependent Claim
21 words
A cardiac arrythmia treatment apparatus according to claim 2 wherein said first and second waveform signals are truncated exponential waveform signals.
Claim 5
Dependent Claim
62 words
A cardiac arrythmia treatment apparatus according to claim 1, wherein said apparatus is a biphasic apparatus, said waveform signal is a second waveform signal, and said apparatus further comprising reverse polarity shock means for delivering a first waveform signal prior to said second waveform signal such that the polarity of said first waveform signal is opposite that of the second waveform signal.
Claim 6
Dependent Claim
162 words
A cardiac arrythmia treatment apparatus according to claim 1, wherein: said apparatus is a biphasic apparatus, said waveform signal is a first waveform signal, said apparatus further comprises reverse polarity shock means for delivering a second waveform signal after said first waveform signal, said second waveform signal having polarity opposite that of said first waveform signal; said detecting means detects an electrical characteristic of said pair of electrodes during delivery of said second waveform signal wherein said electrical characteristic is selected from the group consisting of the voltage across said electrodes and the current through at least one of said electrodes; said time constant calculating means determines a waveform time constant (t s ) from said voltage during said second waveform signal; said membrane voltage calculating means determines when the membrane baseline voltage is reached from said second waveform time constant and said model time constant; and said switch means interrupts said second waveform signal when said membrane baseline voltage is reached.
Claim 7
Dependent Claim
53 words
A cardiac arrythmia treatment apparatus according to claim 5, wherein said apparatus further comprises second storage means for storing a second model time constant (t m ), and said membrane voltage calculating means determines when the baseline membrane voltage is reached from said second waveform time constant and said second model time constant.
Claim 8
Dependent Claim
22 words
A cardiac arrythmia treatment apparatus according to claim 5 wherein said first and said second waveform signals are truncated exponential waveform signals.
Claim 9
Dependent Claim
19 words
A cardiac arrythmia treatment apparatus according to claim 1 wherein said waveform signal is a truncated exponential waveform signal.
Claim 10
Dependent Claim
20 words
A cardiac arrythmia treatment apparatus according to claim 1, further comprising a pair of electrodes connected to said shock means.
Claim 11
Dependent Claim
28 words
A cardiac arrythmia treatment apparatus according to claim 1, further comprising adjusting means operably connected to said storage means for altering said model time constant (t m ).
Claim 12
Dependent Claim
16 words
A cardiac arrythmia treatment apparatus according to claim 1, wherein said apparatus is an implantable apparatus.
Claim 13
Dependent Claim
17 words
A cardiac arrythmia treatment apparatus according to claim 1, wherein said apparatus is an external defibrillation apparatus.
Claim 14
Dependent Claim
127 words
A cardiac arrythmia treatment method, comprising: delivering a waveform signal to a pair of electrodes, said electrodes positioned for defibrillating the heart of a subject; detecting an electrical characteristic of said pair of electrodes during delivery of the waveform signal wherein the electrical characteristic is selected from the group consisting of the voltage across the electrodes and the current through at least one of the electrodes; determining a first waveform time constant (t s ) from the detected electrical characteristic; providing a first model time constant (t m ) for a model response to the waveform; determining when a peak membrane voltage is reached from the waveform time constant and the model time constant; and then interrupting the waveform signal when the peak membrane voltage is reached.
Claim 15
Dependent Claim
127 words
A cardiac arrythmia treatment method, comprising: delivering a waveform signal to a pair of electrodes, said electrodes positioned for defibrillating the heart of a subject; detecting an electrical characteristic of said pair of electrodes during delivery of the waveform signal wherein the electrical characteristic is selected from the group consisting of the voltage across the electrodes and the current through at least one of the electrodes; determining a first waveform time constant (t s ) from the detected electrical characteristic; providing a first model time constant (t m ) for a model response to the waveform; determining when a peak membrane voltage is reached from the waveform time constant and the model time constant; and then interrupting the waveform signal when the peak membrane voltage is reached.
Claim 16
Dependent Claim
32 words
The method of cardiac arrythmia treatment of claim 13, further comprising the step of delivering a second waveform signal of opposite polarity to the first waveform signal to said pair of electrodes.
Claim 17
Dependent Claim
105 words
The method of cardiac arrythmia treatment of claim 14, further comprising the steps of: detecting an electrical characteristic of said pair of electrodes during delivery of the second waveform signal wherein the electrical characteristic is selected from the group consisting of the voltage across the electrodes and the current through at least one of the electrodes; determining a waveform time constant (t s ) from the electrical characteristic during the second waveform signal; calculating when the membrane baseline voltage is reached from the second waveform time constant and the model time constant; and interrupting the second waveform signal when the membrane baseline voltage is reached.
Claim 18
Dependent Claim
51 words
The method of cardiac arrythmia treatment of claim 15, said method further comprising the steps of: providing a second model time constant (t m ); and wherein said calculating step comprises calculating when the baseline membrane voltage is reached from the second waveform time constant and the second model time constant.
Claim 19
Dependent Claim
24 words
The method of cardiac arrythmia treatment of claim 15 wherein the first waveform signal and the second waveform signal are truncated exponential waveform signals.
Claim 20
Dependent Claim
23 words
The method of cardiac arrythmia treatment of claim 14 wherein the waveform signal and the second waveform signal are truncated exponential waveform signals.
Claim 21
Dependent Claim
24 words
The method of cardiac arrythmia treatment of claim 13, said method further comprising the step of adjusting the model time constant (t m ).
Claim 22
Dependent Claim
19 words
The method of cardiac arrythmia treatment of claim 13 wherein the waveform signal is a truncated exponential waveform signal.
Claim 23
Independent Claim
141 words
A method of selecting a cardiac arrythmia treatment apparatus for implantation in a subject, comprising: providing a set of implantable cardiac arrythmia treatment apparatus which deliver a waveform signal, each member of the set having a storage capacitor for delivering the waveform signal, and wherein each member of the set has a storage capacitor with a fixed capacitance different from the other members of the set; implanting a pair of electrodes in a subject, with the electrodes positioned for applying an electric counter-shock to the heart of the subject; then measuring the impedance across the pair of electrodes after implantation; then selecting a cardiac arrythmia treatment apparatus from the set of cardiac arrythmia treatment apparatus based on the impedance and the storage capacitance of the cardiac arrythmia treatment apparatus; and then implanting the selected cardiac arrythmia treatment apparatus in the subject.
Claim 24
Independent Claim
141 words
A method of selecting a cardiac arrythmia treatment apparatus for implantation in a subject, comprising: providing a set of implantable cardiac arrythmia treatment apparatus which deliver a waveform signal, each member of the set having a storage capacitor for delivering the waveform signal, and wherein each member of the set has a storage capacitor with a fixed capacitance different from the other members of the set; implanting a pair of electrodes in a subject, with the electrodes positioned for applying an electric counter-shock to the heart of the subject; then measuring the impedance across the pair of electrodes after implantation; then selecting a cardiac arrythmia treatment apparatus from the set of cardiac arrythmia treatment apparatus based on the impedance and the storage capacitance of the cardiac arrythmia treatment apparatus; and then implanting the selected cardiac arrythmia treatment apparatus in the subject.
Claim 25
Dependent Claim
37 words
The method of selecting a cardiac arrythmia treatment apparatus of claim 21 wherein said selecting step comprises selecting the cardiac arrythmia treatment apparatus having an RC time constant which matches the model time constant of cardiac membrane.
Claim 26
Dependent Claim
59 words
The method of selecting a cardiac arrythmia treatment apparatus of claim 21 wherein said selecting step further comprises the steps of: measuring the model time constant of the cardiac membrane of the subject; and then selecting the cardiac arrythmia treatment apparatus having an RC time constant which matches the model time constant of the cardiac membrane of the subject.
Claim 27
Dependent Claim
25 words
The method of selecting a cardiac arrythmia treatment apparatus of claim 21 wherein said measuring step comprises performing a strength duration analysis of the subject.
Claim 28
Independent Claim
61 words
A method of determining the optimum duration of an electric pulse for electric counter-shock cardiac arrythmia treatment comprising: convolving the waveform of an electric pulse counter-shock signal with the impulse response of a parallel RC circuit having a model time constant to approximate the response of a heart; then determining the peak response time of the waveform from the convolved waveform.
Claim 29
Independent Claim
61 words
A method of determining the optimum duration of an electric pulse for electric counter-shock cardiac arrythmia treatment comprising: convolving the waveform of an electric pulse counter-shock signal with the impulse response of a parallel RC circuit having a model time constant to approximate the response of a heart; then determining the peak response time of the waveform from the convolved waveform.
Claim 30
Dependent Claim
24 words
The method of claim 25 further comprising the step of generating an electric counter-shock pulse having a duration of the determined peak response time.
Claim 31
Independent Claim
63 words
A method of delivering an electric counter-shock pulse to a subject comprising: convolving the waveform of an electric pulse counter-shock signal with the impulse response of a parallel RC circuit having a model time constant to approximate the response of a heart; determining the peak response time of the waveform from the convolved waveform; and delivering said electric counter-shock pulse to a subject.
Claim 32
Independent Claim
63 words
A method of delivering an electric counter-shock pulse to a subject comprising: convolving the waveform of an electric pulse counter-shock signal with the impulse response of a parallel RC circuit having a model time constant to approximate the response of a heart; determining the peak response time of the waveform from the convolved waveform; and delivering said electric counter-shock pulse to a subject.
Claim 33
Dependent Claim
24 words
The method of claim 27 further comprising the step of generating an electric counter-shock pulse having a duration of the determined peak response time.
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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) | 1999-07-30 | 2000-01-29 | 2000-07-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-07-30 | 2004-01-29 | 2004-07-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-07-30 | 2008-01-29 | 2008-07-30 | $7700.00 | Window Closed / Lapsed |