Normal First and Second Heart Sounds Unsplit

Reduced Intensity First and Second Heart Sounds

Splitting of the Second Heart Sound

Third Heart Sound Gallop

Fourth Heart Sound Gallop

Third and Fourth Heart Sound Gallop

Summation Gallop at 120 beats per minute

Fixed Splitting of the Second Heart Sound

Mid-Systolic Click

Mitral Valve Leaflet Prolapse

Aortic Stenosis (Diamond Shaped Systolic Murmur)

Aortic Regurgitation (Decrescendo Diastolic Murmur)

Mitral Regurgitation (Pan-systolic Murmur)

Mitral Stenosis (Diastolic Murmur)

Human Chest Littmann Stethoscope

Chestpiece Position: Mitral
Maneuver: Supine

This is a normal first and second heart sound at 60 beats per minute. You are listening at the Mitral valve area (Apex). The first heart sound has slightly greater intensity than the second heart sound.

  • The first heart sound is produced by the closing of the mitral and tricuspid valve leaflets.
  • The second heart sound is produced by the closing of the aortic and pulmonic valve leaflets.
  • The second heart sound is unsplit when the subject is holding his or her breath at peak expiration.

Chestpiece Position: Mitral
Maneuver: Supine

This is a simulation of a first heart sound and a second heart sound with greatly reduced intensity. This can be seen in an obese patient or a patient with emphysema.

It is a challenge to your ability to hear these reduced intensity sounds.

Chestpiece Position: Pulmonic
Maneuver: Supine

This lesson covers physiologic and paradoxical splitting of the second heart sound.

The second heart sound (S2) is created by the closing of the aortic valve and the closing of the pulmonic valve. The difference in timing between the closure of the aortic and pulmonic valves creates a split second heart sound.

Careful analysis of the splitting and intensity of the second heart sound can indicate the presence of many cardiac abnormalities.

In this example splitting varies between zero and eighty milliseconds depending on the phase of the respiratory cycle.

In physiologic splitting the maximum separation between aortic and pulmonic components of the second heart sound occurs at peak inspiration.

In paradoxical splitting the maximum separation occurs at peak expiration.

Paradoxical splitting can occur with left bundle-branch block (LBBB) and aortic stenosis both of which cause the aortic valve closure to be delayed until after the pulmonic valve closure, reversing the normal sequence of events.

Chestpiece Position: Mitral
Maneuver: Supine

A third heart sound occurs early in diastole. In young people and athletes it is a normal phenomenon. In older individuals it indicates the presence of congestive heart failure.

The third heart sound is caused by a sudden deceleration of blood flow into the left ventricle from the left atrium. In the anatomy tab you will see a thin-walled, dilated left ventricle with generalized decreased vigor of contraction.

In the presence of a third heart sound (S3) the first heart sound is decreased in intensity while the second heart sound is increased in intensity.

The third heart sound is a low frequency sound best heard with the bell of the stethoscope pressed lightly on the skin of the chest.

Chestpiece Position: Mitral
Maneuver: Supine

The fourth heart sound occurs in late diastole just prior to the first heart sound. The first heart sound is decreased in intensity and the second heart sound is increased in intensity.

The fourth heart sound is produced by an increase in stiffness of the left ventricle due to scar tissue formation. This may be a manifestation of coronary heart disease.

A fourth heart sound can also be caused by a greatly thickened left ventricular wall such as with essential hypertension or aortic stenosis. This is shown in the anatomy tab.

A fourth heart sound is never heard with atrial fibrillation because atrial contraction is ineffective.

The fourth heart sound is a low frequency sound best heard with the bell of the stethoscope pressed lightly on the skin of the chest.

Chestpiece Position: Mitral
Maneuver: Supine

Both the third and fourth heart sounds (S3 and S4) are low frequency. S4 is lower than S3.

This is a pattern that occurs with improvement of heart failure. That is, an S3 pattern gives way to an S3 S4 pattern as the patient improves.

Chestpiece Position: Mitral
Maneuver: Supine

At a heart rate of 120 beats per minute, the diastolic period is shortened. This causes the third and fourth sound to be superimposed, creating a single loud sound.

The anatomy tab shows an enlarged left ventricle with decreased left ventricular contractility and a minimally enlarged left atrium.

Chestpiece Position: Pulmonic
Maneuver: Supine

This example shows fixed splitting of the second heart sound. The second heart sound remains unchanged through inspiration and expiration at sixty milliseconds in this example.

Fixed splitting of the second heart sound (along with murmurs) indicates the presence of an Atrial Septal Defect, a congenital heart defect in which the intra-atrial septum is incomplete resulting in a hole between the left and right atria.

The murmurs have been eliminated in this lesson so that you can concentrate on the fixed splitting of the second heart sound.

Chestpiece Position: Mitral
Maneuver: Supine

This is an example of a mid-systolic click heard at the mitral valve area.

The first and second heart sounds are normal . The second heart sound is unsplit and no murmur is present so that you can concentrate on the systolic click.

On the anatomy tab you can see that the mitral valve posterior leaflet prolapses. The mid-systolic click is produced by the sudden prolapse of the leaflet.

A mid-systolic click is often followed by a late systolic murmur of mitral valve leaflet prolapse.

Chestpiece Position: Mitral
Maneuver: Supine

This is an example of Mitral Valve Leaflet Prolapse.

A mid-systolic click is followed by a late systolic diamond shaped murmur.

On the animation tab you can see prolapse of both the anterior and posterior mitral valve leaflets and turbulent flow across the incompetent mitral leaflets (murmur of mitral regurgitation).

Chestpiece Position: Aortic
Maneuver: Sitting

This is an example of a diamond shaped systolic murmur usually associated with aortic stenosis.

The first and second heart sounds are normal. The murmur starts shortly after the first heart sound and ends before the second heart sound.

The murmur is mid to high pitched.

The anatomy tab shows a markedly thickened left ventricle. The aortic valve leaflets are thickened and immobile. The murmur is caused by turbulent flow across the aortic valve leaflets.

Chestpiece Position: Erb's Point
Maneuver: Sitting leaning forward

This is an example of a decrescendo murmur starting early in diastole.

The first and second heart sounds are normal.

The decrescendo murmur is high pitched. The anatomy tab shows a enlarged left ventricle with normal contractility. You can see regurgitant flow from the aorta into the left ventricle which causes the murmur.

Chestpiece Position: Mitral
Maneuver: Supine

This is an example of a pan-systolic murmur usually associated with mitral regurgitation.

The first and second heart sounds are normal.

A mid-frequency rectangular murmur fills all of systole.

In the anatomy tab you can see the enlarged left ventricle and left atrium and turbulent flow from the left ventricle into the left atrium which creates the murmur.

Chestpiece Position: Mitral
Maneuver: Supine

This is an example of a diastolic decrescendo murmur occuring after an opening snap. It is associated with mitral stenosis.

The first heart sound is increased in intensity while the second heart sound is normal. An opening snap is present after the second heart sound. The low pitched rumbling murmur starts after the opening snap and lasts until mid diastole.

On the anatomy tab you can see an enlarged left atrium and thickened but mobile mitral leaflets.

Turbulent blood flow from the left atrium into the left ventricle is responsible for the murmur.