The Mechanism of the Physiologic Disappearance of the Third Heart Sound with Aging.

Abstract

SUMMARYThe 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 217 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=1/24k/m , where Fd is the natural damped frequency and is the damping factor. The equation shows that the vibrating system can oscillate only if is <1. During the growth of the individual the increased myocardial mass may lead to augmented viscous forces causing a gradual increase in until the system becomes overdamped and consequently unable to vibrate causing the disappearance of S3. (Jpn Heart J 1996; 37: 215-226) Key words:Third heart sound Spectral analysis Echocardiography Phonocardiography HE third heart sound (S3) consists of a group of low frequency vibrations, audible or recordable at the point of the maximal apical impulse during early diastole in a high percentage of normal children and healthy young adults; its prevalence characteristically tends to decrease with increasing age.1)Various theories have been proposed to explain both the genesis of S3 and its disappearance with aging.2-6) We already approached the problem of the gen-

Details of left ventricular radial wall motion supporting the ventricular theory of the third heart sound obtained by cardiac MR

“…17 The additional wave of outward radial movement during rapid ventricular filling (wave d in Figures 1-3) corresponds to the expected timing of the third heart sound. Studies involving mechanical correlations have shown that the third heart sound could be related to ventricular wall vibrations during rapid filling, 18,19 and our results support this hypothesis. A schematic representation of LV segments in the cross-section and their relationship to the direction of ventricular inflow is shown in Figure 5.…”

Hemodynamics-driven mathematical model of third heart sound generation

“…Frequency. Figure 2B shows frequency spectrum and relative energy of S3 from experiment ( Longhini et al, 1996 ) and simulation for a healthy subject (with a cardiac output of 5 L/min). Signals were lowpass-filtered with a cutoff frequency of 300 Hz.…”

“…Figure 3A illustrates the relation between the simulated S3 and hemodynamics (pressures, volumes, E and A wave) of one (Liu et al, 2016) and simulation of a healthy subject with a cardiac output of 5 L/min. (B) Frequency spectrum and normalized energy of S3 from experiment (Longhini et al, 1996) and simulation (5 L/min).…”

“…Computational models can help to further understand the mechanisms behind the generation of S3 and provide some insights into these disputes. Several studies ( Held et al, 1984 ; Drzewiecki et al, 1991 ; Longhini et al, 1996 ) constructed models based on the valvular and impact theories, but were then refuted experimentally ( Mehta and Khan, 2004 ). The widely accepted ventricular theory has neither been disproved nor fully corroborated ( Mehta and Khan, 2004 ).…”

A multiple decision trees architecture for medical diagnosis: The differentiation of opening snap, second heart sound split and third heart sound

“…Concerning the (S3), most of the previous research is mainly trying either to explain the mechanism that generates S3, or to find a mathematical model that describes S3 genesis and its physiologic disappearance with aging (Longhini et al, 1996). Additionally some research works try to associate S3 with some heart phenomena, such as ischemic heart disease, transmitral flow etc (Aggio et al, 1990).…”