Prenatal Diagnosis of Hypoplastic Left Heart Syndrome: Can We Optimize Outcomes?

The capacity to diagnose congenital heart disease (CHD) through echocardiography before birth has revolutionized the practice of congenital heart care. The term ‘‘birth defect’’ of the heart is now a misnomer, as ‘‘birth’’ is but an arbitrary point in time in the temporal spectrum of care for these conditions. Fetal diagnosis is currently the most common means for first entry into the system of care of CHD.Inthepast,itwastheacutepresentationofasymptomaticnewborn or detection of a murmur that would prompt inquiry and diagnosis of a cardiac structural abnormality. Today, screening obstetric ultrasound and fetal echocardiography as early as the first trimester of pregnancy are common and allow a wealth of benefits. Counseling and education of families can take place, allowing both physical and psychological preparation for the delivery and future care needs of a child with CHD. Knowledge of the presence of a heart defectallows the creation of a smooth transition from prenatal to postnatal life when the cardiovascular system isat risk. Identification of a congenital heart defect on fetal echocardiography provides the opportunity to avoid deleterious manifestations at birth such as severe hypoxemia or cardiovascular collapse, through the immediate initiation of management. Furthermore, prenatal diagnosis provides the opportunity to contemplate fetal treatment and to entertain strategies that may either alter the natural history of the anomaly and modify cardiac structure or perhaps improve the postnatal outcome, either short or long term. In complex CHD, suchas hypoplastic left heart syndrome (HLHS), prenatal diagnosis specifically enables practitioners to provide a seamless transition to extrauterine life by initiating prostaglandin medication at birth to maintain patency of the ductus arteriosus, thus avoiding instability. Numerous studies have highlighted the benefit of prenatal diagnosis on postnatal morbidity and mortality for HLHS. 1-3 In the current issue of the Journal of the American Society of Echocardiography, Markkanen et al. 4 demonstrate the benefits of prenatal diagnosis on postnatal right ventricular (RV) myocardial performance. They retrospectively reviewed a consecutive cohort of 66 infants with HLHS born in Finland between 2003 and 2010, 25 of whom were prenatally diagnosed. Prenatally diagnosed subjects were all delivered at Helsinki University Hospital and were not routinely intubated for mechanical ventilation or administered inotropic support. In contrast, infants who were postnatally diagnosed were transported to Helsinki University Hospital after diagnosis elsewhere and then stabilized for surgical intervention. Study parameters included lowest arterial pH; highest lactate, alanine aminotransferase, andcreatinine levels;and earlymortality to30days afterthefirststage of surgical palliation, the Norwood procedure. RV myocardial performance was evaluated by calculation of the postnatal global and segmental RV fractional area change (FAC), strain rate, and myocardial velocity from an apical four-chamber view using Velocity Vector Imaging (syngo USWP 3.0; Siemens Healthcare, Erlangen, Germany). The investigators found that prenatally diagnosed infants had better cardiac function before surgery compared with postnatally diagnosed infants (RV FAC 28% vs 21%), although there was no difference in RV FAC between surgical survivors and nonsurvivors. Infants diagnosed prenatally also had less acidosis and better end-organ function as determined by lower alanine aminotransferase and creatinine measures.