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Updated: Jun 26, 2026
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Semi-automated Optical Heartbeat Analysis of Small Hearts
Published on: September 16, 2009
Detection of the third heart sound using a tailored wavelet approach: method verification
P Hult1, T Fjällbrant, K Hildén
1Department of Biomedical Engineering, Linköpings Universitet, Linköping, Sweden. peter.hult@imt.liu.se
Medical & Biological Engineering & Computing
|May 4, 2005
Summary
A new wavelet-based method effectively detects the third heart sound, often indicative of heart failure, surpassing traditional stethoscope auscultation. This advanced technique improves identification of this subtle cardiac indicator.
Area of Science:
- Cardiology
- Biomedical Engineering
- Signal Processing
Background:
- The third heart sound (S3) is a low-frequency cardiac sound normally present in children but absent in adults.
- S3 can reappear in adults with conditions like heart failure, indicating altered myocardial function.
- Its low amplitude and frequency make S3 difficult to detect with traditional stethoscopes.
Purpose of the Study:
- To evaluate the efficacy of a wavelet-based detection method for identifying the third heart sound in patients with heart failure.
- To compare the wavelet method's performance against conventional auscultation (phonocardiography) and echocardiography.
Main Methods:
- A wavelet-based signal processing technique was employed to detect the third heart sound.
- Study 1 assessed the detection rate, missed sounds, and false positives of the wavelet method.
- Study 2 compared the wavelet method's patient identification rate with that of regular phonocardiography.
Main Results:
- The wavelet method detected 87% of third heart sounds, with 12% missed and 6% false positives in the first study.
- In the second study, the wavelet method identified 87% of patients with the third heart sound.
- Conventional phonocardiography identified only 25% of these patients.
Conclusions:
- The wavelet-based method demonstrates high sensitivity and specificity for detecting the third heart sound in heart failure patients.
- This advanced method significantly outperforms traditional phonocardiography in identifying patients with the third heart sound.
- Wavelet analysis offers a promising tool for non-invasive cardiac assessment, particularly for subtle heart sound abnormalities.
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01:15Heart Sounds
Heart sounds are generated by the turbulence in blood flow due to the closing of heart valves. These sounds are best perceived slightly away from the valves, where the blood flow disseminates the sound.
Auscultation is the process of listening to these internal body sounds using a stethoscope. The heart produces four types of sounds, but only two—S1 and S2—can usually be heard with a stethoscope.
S1, also known as the "lub" sound, is caused by the closure of atrioventricular (A-V) valves at the...
Auscultation is the process of listening to these internal body sounds using a stethoscope. The heart produces four types of sounds, but only two—S1 and S2—can usually be heard with a stethoscope.
S1, also known as the "lub" sound, is caused by the closure of atrioventricular (A-V) valves at the...
01:25Assessment of the Cardiovascular System IV: Auscultation
Cardiac auscultation is a clinical skill used to assess heart function and detect abnormalities. It involves listening to heart sounds at specific anatomical locations through a stethoscope.
Normal Heart Sounds
S1 (First Heart Sound)-
S1 is made by the closure of the mitral and tricuspid valves (atrioventricular valves), marking the beginning of systole.
S2 (Second Heart Sound)-
S2 is made by the closure of the aortic and pulmonic valves (semilunar valves), marking the end of the systole.
Normal Heart Sounds
S1 (First Heart Sound)-
S1 is made by the closure of the mitral and tricuspid valves (atrioventricular valves), marking the beginning of systole.
S2 (Second Heart Sound)-
S2 is made by the closure of the aortic and pulmonic valves (semilunar valves), marking the end of the systole.
01:25Cardiovascular System Abnormal Findings II: Auscultation
Auscultation, an essential part of a heart examination, is done using a stethoscope. It provides crucial information about heart function and possible heart problems. Due to heart problems, abnormal sounds can be heard during systole or diastole. These sounds include S3 and S4 gallops, opening snaps, systolic clicks, and murmurs.
Abnormal Heart Sounds
Gallops:
Abnormal Heart Sounds
Gallops: