Method and apparatus for extracting systolic valvular events from heart sounds
First Claim
1. A system for deconvolving the phonocardiogram (PCG) to extract the systolic valvular events, SVE(t), from said PCG for determination of the systolic time intervals (STI), comprising:
- transducer means for converting heart sounds into an electrical phonocardiogram (PCG), electrical means having a transfer function matching the inverse of the Fourier transformation for the transient response wavelet, TRW(f), associated with the fundamental mechanical-acoustical properties of the heart as transduced by said transducer meansmeans applying said PCG to said electrical meansfurther means responsive to signals produced by said electrical means for generating signals corresponding to said SVE(t) to define the temporal boundaries of the STI.
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Abstract
A non-invasive method and means for determining beat-by-beat assessments of a patient'"'"'s cardiac performance by measuring the "pre-ejection phase" (PEP) and the "left ventricular ejection time" (LVET), the aforementioned phrases also being known as the "systolic time intervals" (STI) of the heart. The system accomplishes its function through the following method: transduction of the heart sounds into an electrical phonocardiogram (PCG) signal and controlled amplification thereof; extraction of initial cardiac contraction and aortic valvular events by subjecting the PCG to the general inverse-filtering technique known as "deconvolution"; electronic separation of the PEP, LVET and heart pulse intervals from the deconvolved PCG with microcomputer circuitry comprising microprocessor and digital logic assemblies; precise measurement and simultaneous storage of the PEP, LVET, the PEP/LVET ratio, and the heart rate with the use of electronic digital counters, timers, dividers, and buffer memories after every heart beat; and finally effecting digital readout for instantly displaying the systolic time intervals, their respective ratio, and the heart rate, or for storing them for later use.
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Citations
9 Claims
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1. A system for deconvolving the phonocardiogram (PCG) to extract the systolic valvular events, SVE(t), from said PCG for determination of the systolic time intervals (STI), comprising:
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transducer means for converting heart sounds into an electrical phonocardiogram (PCG), electrical means having a transfer function matching the inverse of the Fourier transformation for the transient response wavelet, TRW(f), associated with the fundamental mechanical-acoustical properties of the heart as transduced by said transducer means means applying said PCG to said electrical means further means responsive to signals produced by said electrical means for generating signals corresponding to said SVE(t) to define the temporal boundaries of the STI. - View Dependent Claims (2, 3, 4)
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8. A method for extracting systolic valvular events, SVE(t), from heart sounds for determination of the systolic time intervals (STI), which comprises:
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(a) transducing the heart sounds into an electrical phonocardiogram signal; (b) deriving from the aforesaid signal the transient response wavelet, TRW(t) and its Fourier transformation, TRW(f), for the heart from the fundamental mechanical-acoustical properties of the biophysical cardiac system; (c) matching said phonocardiogram signal with a system function which is the inverse of said Fourier transformation, TRW(f), over a predetermined range of frequencies, and finally; (d) generating an electrical output from said matched inverse system function which corresponds to the onset of said transient response wavelet, TRW(t), resulting from initial cardial contraction and aortic valvular events that temporally define boundaries for said STI. - View Dependent Claims (5, 6, 7, 9)
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Specification