A single ventricle is a congenital heart defect that occurs due to
abnormal development of the fetal heart during the first eight weeks
of pregnancy. There are many types of single ventricles including
double inlet left ventricle, hypoplastic left heart syndrome, mitral
atresia, tricuspid atresia, and common AV valves with only one
Because of the improper development of the fetal heart, the left or
right ventricle may be underdeveloped. Openings may be present in the
atrial and/or ventricular walls allowing oxygen-poor (blue) blood and
oxygen-rich (red) blood to mix with each other. A series of operations
are necessary in order to re-route the blood so that enough oxygen is
provided to the child.
Why is single ventricle a concern?
This heart defect causes children to be cyanotic (blue) since a
combination of oxygen-poor (blue) and oxygen-rich (red) blood leaves
the heart and goes to the body. Just how much oxygen or how little
oxygen will be in the bloodstream depends on a number of factors. Some
children will only be mildly cyanotic, while others will not have
enough oxygen in the blood to meet the body's needs.