Abstract
Hypoplastic left heart syndrome (HLHS) is characterized by underdevelopment of the left-sided heart structures. The prenatal diagnosis of this congenital heart disease is crucial because a newborn with undiagnosed HLHS often presents with clinical signs of low cardiac output once the ductus arteriosus begins to close. With that in mind, the aim of this article was to perform a non-systematic review focusing on the key ultrasound features that can be used in the prenatal diagnosis of HLHS. Severe forms of HLHS are characterized by a markedly abnormal four-chamber view of the fetal heart (small left atrium, hypoplastic left ventricle, or abnormal mitral valve). The left ventricular outflow tract view allows the degree of hypoplasia in the tract to be evaluated and the diameter of the ascending aorta to be measured. The Z-scores are intended to aid in the diagnosis and follow-up of HLHS. In mild forms of HLHS, a right ventricle/left ventricle length ratio > 1.28 was the strongest predictor of a univentricular outcome.