Rare diseases · Sign or symptom
Paradoxical splitting of the second heart sound
HP:0031663
What it means
Normally, the aortic valve closure (A2) is followed by the pulmonic valve closure (P2) but the A2-P2 interval increases with inspiration and decreases with expiration. With paradoxical splitting, there is a delay in the closure of the aortic valve, so that A2 can follow P2; the individual components can be appreciated at the end of expiration and the interval narrows with inspiration (which is the opposite of the normal pattern).
Rare diseases that can present with this1
The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.
Part of the broader category
Also called: Paradoxical splitting of S2 · Reversed splitting of S2 · Reversed splitting of the second heart sound
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Start free with EleplanThis page uses the Human Phenotype Ontology (2026-06-23) — Human Phenotype Ontology Consortium, hpo.jax.org. Disease associations from Orphanet (INSERM), CC BY 4.0. Content is educational and is not medical advice.