**5.2 Fetal aortic valve stenosis and HLHS**

A group of fetuses with aortic valve stenosis with dilated or normal-sized left ventricles in mid-gestation were found to develop into HLHS [42, 43]. In this group of patients, the aortic stenosis in the developing heart resulted in left ventricular dysfunction, myocardial damage, and decreased left ventricular flow which led to HLHS after birth [43, 44]. However, after successful aortic valvuloplasty for aortic stenosis in human fetus, some patients did not have an improvement in their left ventricle growth and ended up with single ventricle palliation [42]. Therefore, intrinsic defects of left ventricular cardiomyocytes cannot be excluded.
