Physiological Splitting of Second Heart Sound
Components 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)
The Mechanism of Splitting
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
Accentuation of Splitting During Deep Inspiration
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