YMEC software - ANALYSIS OF NORMAL S1 AND S2 IN APEX AND IN BASE, ABNORMAL HYPERDYNAMIC S1 AND ATTENUATED S1

Some of the original report written in April 2003 is replaced by the new results analyzed by using the latest version of DSSF3.

About heartbeat

S1 (first sound) - Closing sound of a mitral valve and a tricuspid valve. It is heard at the early stage of contraction. It is best heard at apex.
S2 (second sound) - Closing sound of an aortic valve and a pulmonary valve. It is heard at the end of contraction. It is best heard at base.
The main auscultatory sites of a heartbeat are an aortic area (base right: 2nd right intercostal space), a pulmonary area (base left: 2nd left intercostal space), a tricuspid valve area (4th intercostal space, at lower left sternal border), and a mitral area (apex: 5th left intercostal space, 1 cm medial to midclavicular line).

List of cardiac auscultation sounds in .wav format

S1 and S2 in apex	S1 is best heard at apex.
S1 and S2 in base	S2 is best heard at cardiac base.
Hyperdynamic S1	This is a case of mitral stenosis.
Attenuated S1	This is a case of mitral insufficiency.
Split S1	Example of physiological S1 split.
Normal split of S2 during respiration	Normally, this split sound is heard on inspiration and becomes single on expiration.

Right click the above link to save the wave file.

Characteristics of normal heartbeat

S1 and S2 sound is heard like "lub- dub". S1-S2 interval is heard during ventricular contraction and S2-S1 interval is heard during expiration. Usually, S1-S2 interval is shorter than S2-S1 interval.
S1 is best heard at apex and S2 is heard at cardiac base.
S2 is mainly caused by the aortic valve closure (A2) and pulmonic valve closure (P2).
Normally, A2 component is heard first and then P2 is heard. Gap between A2 and P2 components become clear at the end of inspiration during the respiratory cycle, because the intrathoracic pressure drops at that time. This drop permits more blood to return to the right heart. The increased blood volume in the right ventricle results in a delayed pulmonic valva closure. At the same time, the capacity of the pulmonary vessels in the lung is increased which results in a slight decrease in the blood volume returning to the left heart. With less blood in the left ventricle, its ejection takes less time resulting in earlier closing of the aortic valve.

Note: Medical explanation and sound files are thanks to "Online clinical exercise" (in Japanese), which was created to support the medical education.

Sound file S1 and S2 in apex was analyzed by DSSF3 version 5. Wave file is loaded from the Running ACF window. Apex is the point at which the first heart sound is mostly audible.

The data is analyzed by the following conditions. The integration time is set to 0.01 s and the running step is set to 0.005 s.

The next figure is the temporal waveform display. The measurement time is 9.02 s, and the sampling rate is 22050 Hz. The recording level seems too high because some of the data is clipped.

The time axis of the previous graph was zoomed x8. This portion contains the first heart sound and the second heart sound.

The next figure is the time history of the sound level, calculated by means of the ACF. In this analysis, the sound level is calculated as average values of 10 ms. I can see that the duration of the first heart sound is longer than that of the second sound.

The time axis of the above figure was zoomed x16. I can see the first heart sound and the second heart sound.

This result is omitted. If you are interested in, try the analysis by following the procedure above. Hereafter, the original report is shown as it was, because the same analysis is available in both the previous version and the latest version of DSSF3.

This is a case of mitral stenosis. The characteristics of this abnormal sound are interpreted as follows.

In this illustration, OS shows the valve opening sound (opening snap). Heart murmur follows this sound.

Next, two typical characteristics of heart murmur at the time of mitral stenosis are illustrated.

First is a low pitched and rumbling murmur. This is called Mid-diastolic murmur, and starts after an opening snap.

Second is a high-pitched murmur and is usually only heard as the "absence of silence" in early diastole. This is called Early diastolic murmur.

This is a heart murmur measured at the third beat. I think that this characteristic murmur can be analyzed in detail by measuring the timing of a valve movement and its acoustical properties as in Heartbeat Measurement 7.

Next, Attenuated S1 is measured by the running ACF. This is a case of mitral insufficiency.

It was zoomed up further to show only one beat. This seems a typical example of Holosysolic murmur as illustrated below.

Two figures illustrate Holosystolic murmur. It begins with the first sound and extends throughout the systolic (contraction) period.

Reference

THE GUIDE to HEART SOUNDS: Normal and Abnormal
Donald W.Novey,M.D.
Marcia Pencak, R.N.,M.S.
John, M.Stang, M.D.
ISBN: 084930153X

Analysis of normal S1 and S2 in apex and in base, abnormal hyperdynamic S1 and attenuated S1 (Heartbeat Measurement 8)

List of cardiac auscultation sounds in .wav format

Characteristics of normal heartbeat

Analysis of normal S1 and S2 in apex and in base, abnormal hyperdynamic S1 and attenuated S1
(Heartbeat Measurement 8)