ABSTRACT
The term hypoplastic left heart syndrome (HLHS) has been used to describe a group of cardiac malformations that consists of hypoplasia or absence of the left ventricle and hypoplasia of the ascending aorta. In the most extreme form, HLHS refers to aortic valvar atresia, with a very diminutive ascending aorta and diminutive left ventricle. Like other single ventricle malformations of the heart, HLHS has a circulation dependent on patency of the ductus arteriosus and obligatory mixing of pulmonary and systemic venous blood. The single ventricle (in this case, an anatomic right ventricle (RV)) supplies the pulmonary circulation by the branch pulmonary arteries (PAs) and the systemic circulation via the patent ductus arteriosus. Flow in the ascending aorta is usually primarily retrograde, and in aortic atresia, the ascending aorta acts as a common coronary artery supplying coronary perfusion.
