Second Heart Sound

The second heart sound category of this website will help you to learn about the second heart sound including physiologically split, second heart sound with persistent splitting, second heart sound with fixed splitting, increases the aortic intensity, and more.

Before you take this session, you should have finished the normal heart sounds session and first heart sound sessions. You should feel gratified with your ability to listen and be familiar with normal heart sounds.
Please use good quality headphones or earphones. Computer or phones speakers often fail to reproduce some heart sounds.

The second heart sound is a short burst of auditory vibrations of varying intensity, frequency, quality, and duration. The second heart sound is produced by the closure of the aortic and the pulmonary valve.
A split-second heart sound (S2 heart sound) is best heard at the pulmonic valve listening post, as P2 is much softer than A2. The A2 sound is normally much booming than the P2 due to higher pressures in the left side of the heart.

Heart rate, sex, age, height, and weight had little or no backlash on the splitting pattern of the second heart sound; 15% of the subjects exhibited fixed splitting of the second sound in either, but not both, in a supine or upright position.

In severe HTN (hypertension), a loud second heart sound may be prolonged and slurred-falsely mimicking a split S2.


  1. Nature: High pitched shorter duration (0.12s)
  2. Sounds: D-U-B (loud and sharp)
  3. Frequency: 50 Hz
  4. Area: it is better heard over the left 2nd intercostals space. 1.5 inch away from the midline.
  5. It occurs after the ‘Apex beat” and carotid pulse, the end of the T-wave of ECG.


  • It indicates the end of ventricular systole and the beginning of ventricular diastole.
  • A clear 2nd HS indicates that semilunar valves are closing properly. i.e there is no regurgitation.

In the medical practices, correct diagnosis and understanding of the case are important. So, while doing auscultation hearing the sounds correctly and identifying the abnormalities in it is important. Having prior practice to the sound will be a plus point for you, as we can do better in things we are familiar with.

So, this site will be a friend in gaining practice in auscultation and learning different cases regarding it. So, practice as much you want and gain your self-confidence, and help for your future practices. This site will always be a friend in need in case of learning about heart sounds.

Second Heart Sound – Physiologically Split 2

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.

Second Heart Sound with Persistent Splitting

In general, second heart sound is produced when the aortic and pulmonic valves are closed. The closure of the aortic valve produces a sound called A2, and the closure of the pulmonic valve produces a sound P2. When these sounds are indistinguishable, a split is heard.

This is the second heart sound with a persistent split. On auscultation, a split is heard between the aortic component and the pulmonic component of the heart sound.

This needs to be auscultated very carefully as this is a brief sound. A persistent kind of split is heard on auscultation.

Second Heart Sound with 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.

Second Heart Sound: Fixed Splitting, Increased Aortic Intensity

Second, heart sound fixed splitting, the increased aortic intensity is seen in patients with a history of long-standing hypertension. Due to a long-standing hypertension condition, the aortic pressure is raised. To distinguish Second heart sound fixed splitting, we use fixed splitting of S2 as a reference.

The leading cause of Second heart sound fixed splitting; increased aortic intensity is essential hypertension. There is an increased thickness of the left ventricular wall.

For auscultation, use the diaphragm of the stethoscope and place it over the aortic region. Perform the auscultation while the patient is sitting. The practitioner should know the exact position for auscultation.

Second Heart Sound: Fixed Splitting, Decreased Aortic Intensity

The pulmonic valve closes after the closure of the aortic valve producing a fixed split-second heart sound. The decrease in the afterload leads to a decreased resistance to the flow of blood from the LV through the valve of the aorta. This, in turn, leads to less regurgitation of blood into the mitral valve causing a decrease in the murmur’s intensity. This is indicative of reduced cardiac output. For auscultation, the diaphragm of the stethoscope is used. The patient should be auscultated in a supine position while sitting and leaning forward. The fixed split S2-decreased aortic intensity is best heard in the second intercostal space.

Second Heart Sound and Late Systolic Click

Second heart sound and late systolic click are just like split second heart sound on auscultation. The late systolic click is observed before the S2; thus, it can be mistaken for a split S2.

The main character of second heart sound and late systolic click is that the first half of the pair is heard as a high-frequency sound of a shorter duration.

The late systolic click disappears on the pulmonic area. This is a differentiating point from split S2. The late systolic click occurs as the result of degenerative activity in the mitral valve leaflet. The closing of the leaflets makes a clicking sound.

Second Heart Sound and a Tumor Plop

Second heart sound followed by tumor polp is a heart sound configuration that imitates a split second heart sound. This occurs in the early phase of the diastole.

The tumor plop cannot be heard in the pulmonic area. In case the practitioner can listen to two different heart sounds, there would be a split-second heart sound. Tumor plop mimics thirds heart sound gallop in terms of timing and frequency.

For auscultation, the patient should be in a supine position. By using the diaphragm of the stethoscope auscultate at the mitral region to detect tumor plop.

Opening Snap and Second Heart Sound

The opening snap is a loud diastolic sound generated by the rapid opening of the mitral valve. It may have a mitral origin. In such a case, it is observed at the apex region after the aortic heart sound.

If an opening snap occurs in early diastole and a single second heart sound, it can imitate a split second heart sound.

An opening snap is usually caused by diseases or thick leaflets of the valves. Difficulty in the opening of these leaflets produces a snapping sound. If the thickening is very severe, then the opening snap will be heard very early during the diastole on auscultation.

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