Physiological splitting of the second heart sound

Phonocardiogram recorded at the left upper sternal border in a healthy child showing physiologic splitting of S₂ that varies with the respiratory cycle. S₂ is split in inspiration and single in expiration.

S₁: first heart sound; S₂: second heart sound; A₂: aortic valve closure sound; P₂: pulmonic valve closure sound.

Graphic 104781 Version 2.0

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