Related Experiment Videos
Fixed subaortic stenosis: anatomical spectrum and nature of progression
1Cardiothoracic Unit, Hospital for Sick Children, London.
Insights
Fixed subaortic stenosis, a narrowing of the left ventricular outflow tract, can be acquired and progress over time. Echocardiography reveals diverse forms and potential for valve involvement, especially after age three.
Area of Science:
- Pediatric Cardiology
- Cardiovascular Imaging
- Congenital Heart Disease
Background:
- Fixed subaortic stenosis (FAS) is a significant cause of left ventricular outflow tract (LVOT) obstruction in children.
- Understanding the natural history and potential for progression of FAS is crucial for timely intervention.
Purpose of the Study:
- To characterize the types and progression of fixed subaortic stenosis in infants and children.
- To investigate the potential for FAS to be an acquired condition with evolving morphology.
Main Methods:
- Retrospective review of echocardiographic studies in 58 infants and children diagnosed with FAS.
- Analysis of lesion types, associated cardiac abnormalities, and serial changes over time.
Main Results:
- FAS was diagnosed at a mean age of 4.8 years, with 71% having associated cardiac defects.
- Four distinct types of FAS were identified, with short segment being most common (81%).
- Serial echocardiograms showed rapid progression in one patient and aortic/mitral valve tethering in four, primarily after age three.
Conclusions:
- Fixed subaortic stenosis may represent an acquired lesion with potential for morphological changes and LVOT obstruction severity progression.
- Early echocardiographic findings in infancy may not always reveal subsequent FAS development.
- Valve involvement is a significant concern that develops with age in patients with FAS.
Abstract:
Retrospective echocardiographic review identified 58 consecutive infants and children with fixed subaortic stenosis. Mean (SD) age at diagnosis was 4.8 (3.6) years (range two days to 14.7 years), and diagnosis occurred in infancy in eight. Associated cardiac abnormalities were present in 41 (71%) whereas fixed subaortic stenosis was an isolated lesion in 17 (29%). Four types of fixed subaortic stenosis were identified: short segment (47 (81%)), long segment (7 (12%)), posterior displacement of the infundibular septum with additional discrete narrowing of the left ventricular outflow tract (3 (5%)), and redundant tissue arising from the membranous septum (1 (2%)). Echocardiographic studies had been performed before the diagnosis of fixed subaortic stenosis in nine patients, all with associated abnormalities. These were performed in infancy in each and showed a "normal" left ventricular outflow tract in six and posterior deviation of the infundibular septum in three. In 16 patients serial echocardiographic studies had been performed after the diagnosis of fixed subaortic stenosis but before surgery of the left ventricular outflow tract. Rapid evolution of short segment to long segment narrowing was seen in one patient, and tethering of the aortic valve or mitral valve developed in a further four patients. Aortic valve or mitral valve involvement was not seen before the age of three years but was common thereafter (10/40 patients, 25%). Fixed subaortic stenosis may be an "acquired" lesion with the potential for changes in form as well as progression in severity of left ventricular outflow tract obstruction.