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US3850169A
Expired / Lapsed
US
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Circuit for detecting initial systole and dicrotic notch
Assignee: National Aeronautics and Space Administration
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Filing: 1973-01-30
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Granted: 1974-11-26
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Expires: 1993-01-30
Abstract
Abstract Circuitry is disclosed for processing an arterial pressure waveform to produce during any one cycle a pulse corresponding to the initial systole and a pulse corresponding to the dicrotic notch. In a first channel, an electrical analog of the arterial pressure waveform is filtered and then compared to the original waveform to produce an initial systole signal. In a second channel, the analog is differentiated, filtered and fed through a gate controlled by pulses from the first channel to produce an electrical pulse corresponding to the dicrotic notch.
Inventors
- 👤 V Gebben
- 👤 J Webb
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 17:34
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/02; A61B5/021; A61B5/72; A61B5/7235; A61B5/7239
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
274 words
Circuitry for producing from a transducer generated electrical analog of an arterial pressure waveform an initial systole spike and a dicrotic notch spike, said circuitry comprising: low pass filter circuit means; a first comparator having a first input adapted to be connected to said transducer and a second input adapted to be connected to said transducer through said low pass filter circuit means; a second comparator having input means and output means; unidirectional low pass filter circuit means; means for connecting said unidirectional low pass filter means between an output of said first comparator and said input means of said second comparator; first unidirectional coupling means having one end connected to said output means of said second comparator to provide discrete initial systole pulses at its other end; a differentiator circuit having input means and output means; a third comparator having input means and output means; a high pass filter connected between said output means of said differentiator and said input means of said third comparator; means for connecting said input means of said differentiator to said transducer; gate means having input means and output means; second unidirectional coupling means connected between said output means of said third comparator and said input means of said gate to supply set pulses to said gate; means for resetting said gate each time the voltage applied to said second input means of said first comparator becomes greater than the voltage applied to said second input means of said first comparator; and third unidirectional coupling means having one end connected to said output means of said gate to produce a dicrotic notch voltage pulse at its other end.
Claim 2
Dependent Claim
274 words
Circuitry for producing from a transducer generated electrical analog of an arterial pressure waveform an initial systole spike and a dicrotic notch spike, said circuitry comprising: low pass filter circuit means; a first comparator having a first input adapted to be connected to said transducer and a second input adapted to be connected to said transducer through said low pass filter circuit means; a second comparator having input means and output means; unidirectional low pass filter circuit means; means for connecting said unidirectional low pass filter means between an output of said first comparator and said input means of said second comparator; first unidirectional coupling means having one end connected to said output means of said second comparator to provide discrete initial systole pulses at its other end; a differentiator circuit having input means and output means; a third comparator having input means and output means; a high pass filter connected between said output means of said differentiator and said input means of said third comparator; means for connecting said input means of said differentiator to said transducer; gate means having input means and output means; second unidirectional coupling means connected between said output means of said third comparator and said input means of said gate to supply set pulses to said gate; means for resetting said gate each time the voltage applied to said second input means of said first comparator becomes greater than the voltage applied to said second input means of said first comparator; and third unidirectional coupling means having one end connected to said output means of said gate to produce a dicrotic notch voltage pulse at its other end.
Claim 3
Dependent Claim
23 words
The circuit of claim 1 wherein each of said first, second and third unidirectional coupling means comprises a serially connected capacitor and diode.
Claim 4
Dependent Claim
69 words
The circuit of claim 1 wherein said differentiator circuit comprises an operational amplifier having first and second inputs and an output; a first capacitor and a first resistor serially connected between said second input of said amplifier and said transducer, said first input being connected to circuit common; a second capacitor and a second resistor connected in parallel between said output and said second input of said operational amplifier.
Claim 5
Dependent Claim
22 words
The circuit of claim 3 and including first and second zener diodes connected in back to back relationship across said second resistor.
Claim 6
Dependent Claim
21 words
The circuitry of claim 1 and including impedance matching means interposed between said first comparator and said unidirectional low pass filter.
Claim 7
Dependent Claim
49 words
The circuitry of claim 1 wherein said unidirectional low pass filter comprises a diode and a resistor connected in parallel relationship between the output of said first comparator and the input of said second comparator, a capacitor being connected from the input of said second comparator to circuit common.
Claim 8
Dependent Claim
134 words
The circuit of claim 1 wherein said gate means comprises a first multIvibrator having an output, a set input and a reset input, said second unidirectional coupling means being connected to the set input of the first multivibrator, said third unidirectional coupling means being connected to the output of said first multivibrator; and wherein said means for resetting said gate comprises a second multivibrator having an output, a set input and a reset input; fourth unidirectional coupling means connected between the output of said second multivibrator and the reset input of said first multivibrator; fifth unidirectional coupling means connected between the set input of said second multivibrator and said output of said first comparator; and means connecting said other end of said first unidirectional coupling means to the reset input of said second multivibrator.
Claim 9
Dependent Claim
21 words
The circuitry of claim 7 wherein said fourth and fifth unidirectional coupling means each comprise a serially connected capacitor and diode.
Claim 10
Dependent Claim
82 words
The circuit of claim 1 wherein said first and third comparators each comprise an operational amplifier having an output and input means; a resistor and a zener diode serially connected between each amplifier output and circuit common, the output of each comparator being the voltage between the resistor and the zener diode, said input means of the first amplifier being connected to said low pass filter circuit and said input means of the second amplifier being connected to said high pass filter.
Claim 11
Dependent Claim
71 words
The circuit of claim 9 wherein said input means of said first amplifier comprises first and second inputs, and said low pass filter circuit comprises a resistor having one end connected to the second input of said first amplifier to the other end adapted to be connected to said transducer and a capacitor connected from said second input to circuit common; said second input adapted to be connected to said transducer.
Claim 12
Dependent Claim
270 words
Apparatus for processing an electric analog voltage of an arterial pressure wave as generated by a transducer comprising; means for filtering said electrical analog to remove components above a predetermined frequency and to introduce a time lag; means for producing a square voltage pulse each time said electrical analog is greater in magnitude than the filtered analog; means causing the trailing edge of each of said square voltage pulses to decay exponentially; means for producing a square voltage pulse each time said exponential decay goes below a predetermined level and lasting until the occurrence of the leading edge of the next of said first mentioned square pulses; initial systole output means; means for coupling the leading edge of said second mentioned square wave pulses to said initial systole output means; means for differentiating said electrical analog; means for filtering the differentiated analog to remove components below a predetermined frequency, the differentiated and filtered analog being essentially a second derivative waveform with respect to time of said analog; means responsive to said last named means for producing a switching voltage which switches from a high-to-low-to-high value in accordance with changes in slope of said analog; gate means; second coupling means for transmitting said switching voltage to an input of said gate means; means for opening said gate once each cycle for the first pulse received from said second coupling means to produce a square voltage pulse at an output of said gate; dicrotic notch output means; and third coupling means for passing a wave front of predetermined polarity from said output of said gate means to said dicrotic notch output means.
Claim 13
Dependent Claim
270 words
Apparatus for processing an electric analog voltage of an arterial pressure wave as generated by a transducer comprising; means for filtering said electrical analog to remove components above a predetermined frequency and to introduce a time lag; means for producing a square voltage pulse each time said electrical analog is greater in magnitude than the filtered analog; means causing the trailing edge of each of said square voltage pulses to decay exponentially; means for producing a square voltage pulse each time said exponential decay goes below a predetermined level and lasting until the occurrence of the leading edge of the next of said first mentioned square pulses; initial systole output means; means for coupling the leading edge of said second mentioned square wave pulses to said initial systole output means; means for differentiating said electrical analog; means for filtering the differentiated analog to remove components below a predetermined frequency, the differentiated and filtered analog being essentially a second derivative waveform with respect to time of said analog; means responsive to said last named means for producing a switching voltage which switches from a high-to-low-to-high value in accordance with changes in slope of said analog; gate means; second coupling means for transmitting said switching voltage to an input of said gate means; means for opening said gate once each cycle for the first pulse received from said second coupling means to produce a square voltage pulse at an output of said gate; dicrotic notch output means; and third coupling means for passing a wave front of predetermined polarity from said output of said gate means to said dicrotic notch output means.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-11-25 | 1978-05-27 | 1978-11-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-11-25 | 1982-05-27 | 1982-11-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-11-25 | 1986-05-27 | 1986-11-26 | $7700.00 | Window Closed / Lapsed |