fixed subaortic stenosis
Findings
No curated finding names fixed subaortic stenosis yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.
Definition
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.
Definition from the Mondo Disease Ontology (MONDO:0017727), read 2026-09-29. CC BY 4.0.
Features
28 features
What the disease is reported to present with, and how often among people who have it — never how often a feature means the disease. HPO, annotations 2026-09-02.
- Abnormal heart morphologyHPOHP:0001627
- Frequent (30% to 79% of cases)
- Aortic regurgitationHPOHP:0001659
- Frequent (30% to 79% of cases)
- Congestive heart failureHPOHP:0001635
- Frequent (30% to 79% of cases)
- Diastolic heart murmurHPOHP:0031668
- Frequent (30% to 79% of cases)
- DyspneaHPOHP:0002094
- Frequent (30% to 79% of cases)
- Exertional dyspneaHPO
Where it sits
- Narrower terms (2)