Auscultation in Primary Care

First and Second Heart Sounds – Normal and Unsplit

This sound is normal first and second heart sounds at 60 beats per minute


It occurs due to the sudden closure of A-V valves (tricuspid and mitral valves) at the onset of the ventricular systole.


  1. Nature: Dull, low pitched, prolonged duration: 0.15 sec.
  2. Sound like the word: L-U-B.
  3. Frequency: 25-45 HZ
  4. Area: it is best heard over the left 5th inter-coastal space just medial to mid-clavicular line.
  5. It coincides with the apex beat and carotid pulse and the spike of R-wave of ECG.

First and Second Heart Sounds – Reduced Intensity

The decreased intensity of first heart sound (S1) occurs in conditions that cause the Artio-ventricular (AV) valves to close before ventricular systole or if there is a reduction in the rate of intraventricular pressure development.

First-degree heart block is the most common cause of decreased intensity of the first heart sound. The sound can be also produced by the viral infections of the heart and decreased thyroid function. It is due to a decrease in the ability of contraction of the left ventricle.

Second Heart Sound – Splitting

An increase in the magnitude of the sound between the first and second components of heart sound is known as a physiological split of the second heart sound.

This occurs due to the delay in the closure of the pulmonary valve. The inspiration causes prolongation of right ventricular mechanical systole.

However, it seems reasonable from physiologic studies that inspiratory shortening of left ventricular systole resulting in an earlier aortic closure. This not a pathological condition. The early closure of the aortic systole leads to the physiological split of the second heart.

Third Heart Sound Gallop

A low-frequency sound is heard with vibrations for a brief period at the early diastolic period. The term gallop was previously used to define three heart sounds occurring in succession. This is a bruit that completes the triple rhythm of the heart. This happens when the mitral valve opens and the heart starts to fill passively.

The auscultation of the third heart sound is very difficult, and it all depends on the practitioner’s auscultatory skills. This sound has a very low intensity which gets masked easily by external sounds and lung sounds.

This sound has a minimal radiation capacity and thus can be heard only in certain areas. For the auscultation of third heart sound, gallop raise the bed to make it comfortable for the examiner to auscultate. The third heart sound gallop is only heard if the patient is lying on its side.

Fourth Heart Sound Gallop

The fourth heart sound is also called the atrial gallop or presystolic heart sound. This occurs ahead of S1 when the contraction of atria forces the blood into the left ventricle. This is also a low-pitched voice arising shortly before the first heart sound.

This sound is occasionally present in healthy people, but mostly it is associated with the hypertrophy of ventricles, IHD, aortic stenosis, etc. It is a significant sign of diastolic heart failure.

This sound is also heard in older adults with less ventricular compliance. If you can palpate the fourth heart sounds gallop, there might be the risk of hypertension and cardiac pneumonia to the patient. Other causes of this gallop are delays in completion of the heart cycle.

Third and Fourth Heart Sound Gallop

The third and fourth heart sound gallop is heard when the heart is improving from the failure. The frequency of S4 is less than S3. The S3 configuration gives way to an S3 S4 configuration as the patient recovers.

To detect the third and fourth heart sound, gallop the bell of the stethoscope should be used. The practitioner should be skilled because this sound is only for a brief period. Ask the patient to go in the supine position and place the stethoscope bell over the Mitral region. A third and fourth heart sound gallop is heard during the diastole.

Summation Gallop at 120 beats per minute

The diastolic period is shortened when the heart is beating at the rate of 120 beats per minute. This leads to summation gallop. The third and fourth heart sounds get superimposed, and a single large sound is produced. This happens when the left ventricle is enlarged with decreased contraction in the left ventricle. The left atrium is also enlarged to some extent.

For auscultation, the patient should be in a supine position. To auscultate summation gallop, use the diaphragm of the stethoscope. Place the diaphragm over the mitral region and hear the sound. A single large sound is heard.

Second Heart Sound – Fixed Splitting

During heart examination, fixed splitting is not a common finding. But when present, second heart sound fixed splitting is indicative of an atrial septal defect. In atrial septal defect, altered heart hemodynamics produce a fixed split. During inhalation, there is an increased venous return and increased blood flow through the pulmonic valve, which leads to a delay in its closure, producing a fixed split S2.

The aortic valve closes ahead of the pulmonic valve. The delay in the closure of the pulmonic valve results in a fixed split. The closing pressure on the left side is less than that on the right side. Fixed split S2 may also be indicative of the right bundle branch block.

Mid-Systolic Click

Mitral Valve Leaflet Prolapse

Aortic Stenosis (Diamond Shaped Systolic Murmur)

This is a case of mild aortic stenosis in a patient with rheumatism in combination with mild aortic regurgitation.

The first echo of the heart is normal.

The second tone of the heart is high pitched.

An aortic click is made in systematic, followed by a systolic murmur shaped like a diamond.

The first two-thirds of the diastole were occupied by a high-pitched degeneration murmur.

The aortic valve is mildly unstable and the ventricular left of the diastole is slightly rebounded by turbulent flows.

The chaotic flow of blood induces systemic and diastolic whispering.

Aortic Regurgitation (Decrescendo Diastolic Murmur)

The following is an example of aortic and mitral valves’ significant regurgitation.

Due to the minimum closing of the mitral valve leaflets, the first heart son is decreased minimally in early systole. The second sound of the heart is natural.

The rest of the systole is drawn from the rectangular murmur and the decrescendo murmur makes up much of the diastole. Both whisperings are moderately intense.

The mixture of the two whisperings gives a sound character back and forth.

The left atrium and the left ventricle are extended to the tab in anatomy.

The left ventricle (the systolic murmuring) is rejuvenating, chaotic, streaming from the aorta throughout the left ventricular flow (the diastolic whispering). The left flow is tumultuous. It is rejuvenated.

Mitral Regurgitation (pansystolic Murmur)

Mitral regurgitation is the backward blood leakage through the mitral valve. 

See the mitral valve regurgitation animation. 

During contraction, a leaked mitral valve permits the flux of blood in two ways. 

A holosystolic (pansystolic) murmurs are the cardinal sign of mitral regurgitation and are better heard on the apex using the stethoscope diaphragm while the person is on the left side of the decubitus. 

The systolic murmur in mild MR can be abbreviated or can take place late in the systole.

Mitral Stenosis (Diastolic Murmur)

Stenosis of the mitral valve-or mitral stenosis is the closing of the mitral valve of the heart. This irregular release valve does not function correctly and prevents the flow of blood into the heart’s main pumping chamber.

f the withdrawal valve leaflets get moderately thickened, the first heart tone increases in volume. Silent is Systole. When mitral stenosis rises, the original snap happens sooner.

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