The Mechanism of the Physiologic Disappearance of the Third Heart Sound with Aging
The third heart sound (S3) is often present in children and adolescents but is not present in most adults. Applying at the left ventricle a mathematical model, the mechanism of the disappearance of S3 was studied employing the frequency analysis of the sound and echocardiographic data. The existence...
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Published in | Japanese Heart Journal Vol. 37; no. 2; pp. 215 - 226 |
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Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
Tokyo
International Heart Journal Association
1996
Japanese Heart Journal Association |
Subjects | |
Online Access | Get full text |
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Summary: | The third heart sound (S3) is often present in children and adolescents but is not present in most adults. Applying at the left ventricle a mathematical model, the mechanism of the disappearance of S3 was studied employing the frequency analysis of the sound and echocardiographic data. The existence of a significant correlation between the spectrum energy of S3 and the diameter and thickness of the left ventricle at the moment of S3 in 25 healthy subjects (aged 21±7 years) allowed us to interpret the origin of S3 based on a viscoelastic oscillating system. Once the left ventricle starts vibrating it behaves as a simple physical model composed of a mass (m), a spring (k) and a viscous element. The abrupt deceleration of the blood mass (m) against the left ventricular walls (k) triggers the vibration of the system according to the equation Fd=1/2π√4k/m•√1-ξ2, where Fd is the natural damped frequency and ζ is the damping factor. The equation shows that the vibrating system can oscillate only if ζ is <1. During the growth of the individual the increased myocardial mass may lead to augmented viscous forces causing a gradual increase in ζ until the system becomes overdamped and consequently unable to vibrate causing the disappearance of S3. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0021-4868 1348-673X |
DOI: | 10.1536/ihj.37.215 |