Definition:

Univentricular heart is a term used to describe a wide variety of structural cardiac abnormalities associated with a functional single ventricular chamber. Truly solitary ventricles are exceedingly rare. It is generally agreed that the atrioventricular connection is central in defining the univentricular heart. More specifically, the well-developed ventricle may be designated left, right, or indeterminate. Clinical manifestations hinge on the presence or absence of pulmonary outflow obstruction. Without pulmonary stenosis, infants with low pulmonary resistance present with signs and symptoms typical of large left-to-right shunting, ie, congestive heart failure and failure-to-thrive. A certain degree of pulmonary stenosis is physiologically desirable to prevent pulmonary overcirculation. However, severe pulmonary stenosis or atresia may result in profound hypoxemia and cyanosis.