What are the two variations of S2 heart sounds?

What are the two variations of S2 heart sounds?

• A. Physiological and fixed
• B. Pathological and paradoxical
• C. Acute and chronic
• D. Early and late

Answer: (B)

S2 splitting depends on the timing of the aortic (A2) and pulmonic (P2) valve closures. The normal, physiologic pattern is a temporary separation that widens with inspiration and narrows with expiration. Beyond this normal variation, two abnormal patterns are commonly described: fixed splitting, where the interval between A2 and P2 stays split no matter whether you breathe in or out (often seen with an atrial septal defect due to constant delay in P2 closure); and paradoxical (reversed) splitting, where the order of closure is flipped—P2 occurs before A2—so the split is more pronounced on expiration and may diminish or disappear with inspiration (occurring with conditions like left bundle branch block or severe aortic valve disease). The term pathological is a broad category for abnormal S2 findings, but the classic distinct variations beyond normal are fixed and paradoxical splitting.

S2 splitting depends on the timing of the aortic (A2) and pulmonic (P2) valve closures. The normal, physiologic pattern is a temporary separation that widens with inspiration and narrows with expiration. Beyond this normal variation, two abnormal patterns are commonly described: fixed splitting, where the interval between A2 and P2 stays split no matter whether you breathe in or out (often seen with an atrial septal defect due to constant delay in P2 closure); and paradoxical (reversed) splitting, where the order of closure is flipped—P2 occurs before A2—so the split is more pronounced on expiration and may diminish or disappear with inspiration (occurring with conditions like left bundle branch block or severe aortic valve disease). The term pathological is a broad category for abnormal S2 findings, but the classic distinct variations beyond normal are fixed and paradoxical splitting.