Subvalvular aortic stenosis, muscular type
Subvalvular aortic stenosis (SAS) is the second most common type of aortic stenosis, accounting for 14% of left ventricular outflow tract (LVOT) obstruction, with valvular aortic stenosis being the most common cause (70%).1 The prevalence of SAS is 6.5% of all the adult congenital heart diseases.2 It predominantly involves males, with a male‐to‐female ratio of 2:1. SAS is associated with defects such as VSD, AVSD, or conotruncal anomalies in 60% of cases and may develop after patch closure of a perimembranous or malaligned VSD or AVSD.3, 4
SAS is considered an acquired disease. It is rarely diagnosed during infancy, but it often manifests in the first decade of life with features of progressive LVOT obstruction, left ventricular hypertrophy (LVH), and aortic regurgitation (AR).5 A familial form of this disease, Shone syndrome, has also been described