Basics of love Sounds – S1 and also S2

There space 2 main heart sound that can be heard throughout auscultation: S1 and also S2, additionally affectionately well-known as ‘lub’ and also ‘dub’ respectively.

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Normal love sounds. Source:University of Michigan Murmur library

S1corresponds come the close up door of the mitral and also tricuspid valves during systole. During systole, ventricular press rises, resulting in opening of the aortic and pulmonary valves as well as closure the the mitral and also tricuspid valves.

S2corresponds come the closeup of the door of the aortic and pulmonary valves in ~ the start of diastole. S2may be subdivided right into aortic (A2) and also pulmonary (P2) sounds as the aortic valve closes slightly prior to the pulmonary valve. The splitting in between A2and P2can it is in exaggerated by inspiration, an especially in young individuals.

The pulse can be felt during systole between S1and S2. This is particularly important because that differentiating in between systolic and diastolic murmurs (covered independently here), as well as identifying any type of pathological love sounds.

Pathological Extra heart Sounds – Clicks, Snaps, S3/S4

Ejection systolic click
Ejection systolic click in aortic stenosis and also pulmonary stenosis

Ejection systolic click v ejection systolic murmur. Source: college of Michigan Murmur library


Mid-systolic click
Mid-systolic click in mitral valve prolapse

Midsystolic click. Source: college of Michigan Murmur library

Cause: Mitral valve prolapse

Opening snap
Opening snap watched in mitral stenosis and tricuspid stenosis

Opening snap with mid-diastolic murmur. Source: university of Michigan Murmur library


S3and S4
Pathological S3 and S4 love sounds

S3 and also S4 room extra heart sounds developing after S2.

S3 heart sound. Source: university of Michigan Murmur library

S3 occurs throughout ventricular filling. It can be a regular finding in civilization aged 40 or under. Pathological causes are mostly related to love failure and include:

Ischaemic love diseaseDilated cardiomyopathyHypertrophic cardiomyopathyMitral regurgitation

S4 heart sound. Source: university of Michigan Murmur library

S4 arises once the atria contract against a stubborn ventricle (such as in claims of ventricular hypertrophy). Reasons include:

HypertensionPulmonary hypertensionAortic stenosisHypertrophic cardiomyopathyTumour plop

A rare diastolic love sound classically associated with the motion of the tumour in atrial myxomas.

Changes in Volume

The loudness of love sounds deserve to be transformed by changes in the pressure of valve closure.

Loud S1


Loud A2

Cause: Systemic hypertension

Loud P2­


Pulmonary hypertension

Pathological transforms inS2

Wide-splitting S2– separating increases v inspiration:

Wide-splitting of S2. Splitting increases with inspiration.


Right bundle branch block

Fixed separating S2– splitting not influenced by breathing:

Fixed dividing of S2. Dividing is not influenced by inspiration.

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Cause:Atrial septal defect

Reversed dividing S2­– separating decreases with catalyst (so much so the it deserve to lead to P2 arising before A2):

Reversed separating of S2. Dividing decreases with impetus (and have the right to lead to P2 occurring before A2).