If S2 splitting is audible during expiration, this suggests what?

• A. Heart disease
• B. Normal variation
• C. RV failure only
• D. ASD only

Answer: (A)

Audible S2 splitting during expiration is not normal. Normally, S2 splits with inspiration because the pulmonic component (P2) is delayed more as you inhale; on expiration the two components merge into a single sound. If the split persists when you’re exhaling, it means P2 remains delayed even without the inspiratory effect—indicating abnormal right-sided or pulmonary physiology, which points to heart disease affecting the pulmonary circulation or right heart load. That’s why this pattern suggests a cardiac problem rather than a benign variation.

It isn’t simply a normal variation, which would disappear on expiration. It isn’t uniquely diagnostic of right ventricular failure, since that too is a broader process; and while ASD can cause a wide split, it typically presents as a fixed splitting across respiration, not just a split during expiration.