Page 98 - Clinical Pearls in Cardiology

86 Clinical Pearls in Cardiology

4. How do you clinically identify widely split S2?
For A2 and P2 to be heard as separate sounds, there
should be an interval of at least 30 milliseconds between
them. In normal persons, the splitting of S2 (A2–P2 split)
in the pulmonary area is obvious only during inspiration
because of the prolonged pulmonary hangout interval
and increased venous return during inspiration (Fig. 3).
During expiration, S2 is normally heard as a single sound
because the A2 and P2 components are separated by less
than 20 milliseconds. If the A2 and P2 components are
heard as separate components in the pulmonary area
during expiration (especially in the sitting or standing
posture), then the A2–P2 split is said to be wide (Fig. 4). This
wide splitting can be either mobile or fixed depending on
whether the normal inspiratory variation (i.e. increase
of split with inspiration) is present or not.

Fig. 3: A2–P2 split during inspiration

Fig. 4: A2–P2 split during expiration