Above. Post-delivery anatomy valvar aortic stenosis (AS). AS is a narrowing or obstruction of the left ventricular outflow tract (LVOT). Valvar AS is a narrowing which occurs at the level of the valve and is the most common type. A normal aortic valve has 3 leaflets or cusps and in 3/4ths of the children with valvar AS, the valve has only 2 leaflets. Over time, the valve becomes calcified and may lead to obstruction. Domed aortic valves occur less commonly but may represent a more serious form.
Above. Post-delivery anatomy subaortic stenosis. (SAS). SAS is defined as narrowing or obstruction below the level of the aortic valve and can be discrete or long-segment (tunnel stenosis). Discrete: A membranous diaphragm is a result of endocardial injury, or subsequent proliferation and fibrosis due to turbulence in an abnormally shaped left ventricular outflow tract. Tunnel: Long, fibromuscular narrowing of the left ventricular outflow tract, which may be present with other left ventricular abnormalities.