Second Heart Sound - Physiologically Split 1

Description

The second heart sound (S2) is a short burst of auditory vibrations of varying intensity, frequency, quality, and duration. It has two audible components, the aortic closure sound (A2) and the pulmonic closure sound (P2), which are normally split on inspiration and virtually single on expiration. S2 is produced in part by hemodynamic events immediately following closure of the aortic and pulmonic valves. The vibrations of the second heart sound occur at the end of ventricular contraction and identify the onset of ventricular diastole and the end of mechanical systole. The second heart sound is of shorter duration and higher frequency than the first heart sound. It has two audible components, the aortic closure sound (A2) and the pulmonic closure sound (P2), which must be separated by more than 20 msec (0.20 sec) in order to be differentiated and heard as two distinct sounds. It is clinically very important to determine the presence and degree of respiratory splitting and the relative intensities of A2 and P2.
Splitting is best identified in the second or third left ICS, since the softer P2 normally is confined to that area, whereas the louder A2 is heard over the entire precordium, including the apex. In order to appreciate splitting of S2, it may be useful to gradually move the stethoscope ("inching") from the second right ICS to the fourth left ICS.
Second Heart Sound - Physiologically Split 1

Maneuver: Supine
Chestpiece Position: Pulmonic
Chestpiece: Diaphragm

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