Physiologic S2 splitting occurs how?

Physiologic S2 splitting occurs how?

• A. Splits during inspiration and disappears on expiration
• B. Splits during expiration and disappears on inspiration
• C. Fixed splitting
• D. Never splits

Answer: (A)

Normal physiologic S2 splitting arises from the timing difference between the aortic (A2) and pulmonic (P2) valve closures. During inspiration, increased venous return to the right heart lengthens right ventricular systole and delays P2 closure, so A2 and P2 are heard separately as a wider split. During expiration, venous return decreases and the right ventricle finishes earlier, making P2 occur closer to A2 so the sounds fuse and the split disappears. This pattern—split with inspiration that disappears on expiration—is the classic physiologic finding.

Normal physiologic S2 splitting arises from the timing difference between the aortic (A2) and pulmonic (P2) valve closures. During inspiration, increased venous return to the right heart lengthens right ventricular systole and delays P2 closure, so A2 and P2 are heard separately as a wider split. During expiration, venous return decreases and the right ventricle finishes earlier, making P2 occur closer to A2 so the sounds fuse and the split disappears. This pattern—split with inspiration that disappears on expiration—is the classic physiologic finding.