Physiological Splitting of Second Heart Sound

Second heart sound (S2) is produced due to the closure of semilunar valves.
Semilunar valves include:
- Aortic valve: between the left ventricle and aorta
- Pulmonary valve: between the right ventricle and pulmonary artery
So actually there are two components of second heart sound:
- Aortic component (A2)
- Pulmonary component (P2)

Pressure in the aorta is higher than that in the pulmonary artery

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The aortic valve closes slightly before the closure of the pulmonary valve

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The sound of closure of the aortic valve is produced a bit earlier than that of the pulmonary valve

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Splitting of S2 into A2 and P2 components

Deep inspiration

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Intrathoracic pressure becomes more negative

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Venous return to the right heart increases as compared to that in the left heart

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Emptying of the right ventricle takes a little longer than the left ventricle

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Closure of pulmonary valve is delayed

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Accentuation of splitting of second heart sound

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