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Time-frequency transforms: a new approach to first heart sound frequency dynamics
J C Wood1, A J Buda, D T Barry
1Department of Internal Medicine, University of Michigan Medical School, Ann Arbor 48109.
IEEE Transactions on Bio-Medical Engineering
|July 1, 1992
Summary
The first heart sound frequency increases during the isovolumic contraction period. New time-frequency analysis reveals rapid frequency dynamics, improving cardiac mechanical assessment.
Area of Science:
- Cardiology
- Biomedical Engineering
- Signal Processing
Background:
- The first heart sound (S1) originates from complex cardiac events.
- Understanding S1 frequency dynamics is crucial for assessing cardiac mechanics.
- Traditional analysis methods struggle with the rapid frequency changes in S1.
Purpose of the Study:
- To test the hypothesis that first heart sound frequency rises during isovolumic contraction.
- To evaluate the efficacy of the Binomial joint time-frequency transform for analyzing S1.
- To explore the potential of time-frequency analysis for mechanical assessment of cardiac structures.
Main Methods:
- Utilized the Binomial joint time-frequency transform, a novel analytical tool.
- Recorded cardiac vibrations from eight open-chest dogs using epicardial accelerometers.
- Ensured a wide frequency response (0.1-400 Hz) for the recording system.
Main Results:
- Identified three distinct time-frequency spectral patterns in S1.
- Observed a frequency rise from 40-140 Hz post-ECG R-wave within 30-50 ms.
- Detected a secondary 60-100 Hz component during mid-isovolumic contraction.
Conclusions:
- The Binomial transform offers superior resolution compared to spectrographs and spectrograms.
- Rapid frequency dynamics of S1 necessitate advanced non-stationary analysis techniques.
- Time-frequency transforms can reveal S1 frequency onset and dynamics for mechanical cardiac assessment.