NCIt definition : An umbrella term used to describe several very different complex congenital heart
defects that share the same problem: the heart has only one functional ventricle (anatomically
right or left or indeterminate) supplying the systemic circulation. These defects
include tricuspid atresia, hypoplastic left or right heart syndrome, double outlet
right ventricle, double inlet left ventricle, and other forms of single ventricle
defects.;