Hypoplastic left heart syndrome in the fetus: Diagnostic features prior to birth and their impact on postnatal outcome

Hypoplastic left heart syndrome encompasses a diverse group of heart defects that share the common feature of underdevelopment of the left heart. There are multiple anatomic substrates involved in the development of hypoplastic left heart syndrome, as well as variants of classic hypoplastic left heart, that may signify unique risks and benefits. Additionally, other functional and anatomic cardiac findings as well as extracardiac anomalies are frequently associated with hypoplastic left heart syndrome and have significant impact on outcome. Through a careful, systematic approach, fetal echocardiography can detect many of the anatomic and functional details that contribute to outcomes. Detailed fetal ultrasound and fetal karyotype will diagnose many of the non-cardiac lesions that can be found with hypoplastic left heart syndrome. Parents must also be counseled of risk factors that may not be detected in utero. Knowledge of the specific diagnostic features that can affect outcome allows the fetal cardiologist to obtain all the necessary details, and provides the most accurate assessment of probable outcome in each individual patient.