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Start free with EleplanFixed subaortic stenosis
ORPHA:3092Morphological anomaly
What it is
Fixed subaortic stenosis (FSS) is a rare heart malformation characterized by the obstruction by membranous or fibromuscular tissue of the left ventricular outflow tract (LVOT) below the aortic valve, that occurs as an isolated lesion or in association with additional cardiac malformations (e.g. ventricular septal defect, patent ductus arteriosus, coarctation of the aorta), that presents in childhood with signs of LVOT obstruction (e.g. dyspnea, chest pain, syncope, palpitations) and that can potentially lead to life-threatening complications (e.g. aortic regurgitation, infective endocarditis). It comprises three anatomical subforms: discrete fixed membranous subaortic stenosis (membranous tissue encircling the LVOT), discrete fibromuscular subaortic stenosis (fibromuscular tissue encircling the LVOT) and tunnel subaortic stenosis (fibromuscular diffuse tunnel-like narrowing of the LVOT), the two latter forms being generally more severe than the membranous form.
Key facts
- Age of onset
- Childhood
- Inheritance
- No data available
- Classified as
- Morphological anomaly
Signs and symptoms
Common30–79%
11These ranges are how often a sign appears across everyone diagnosed, not a prediction for one person — most people have some of these and not others. Orphanet also records findings that are specifically absent in this disease; those are in the data but not listed here.
ICD-10 codes
ICD-10 has no distinct code for most rare diseases, so many are filed under the nearest available one. A shared code identifies the group, not this disease — the ORPHAcode above is what identifies it.
Cross-references
Orphadata Science: Free access data from Orphanet. © INSERM 1999. Data version 2026-06-23. Available under CC BY 4.0. This is a reference, not medical advice.
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