Commentary: The heart of symptomatic neonatal Ebstein anomaly: Negative interventricular interaction and ventricular myopathy

Right ventricular myopathy and left ventricular compression of a symptomatic neonate.

Central Message.

Symptomatic newborn infants with Ebstein anomaly have physiologic and anatomic pathology that benefit from Starnes palliation when operative intervention is necessary.

See Article page 128.

Patients with Ebstein anomaly demonstrate a wide array of clinical presentations primarily rooted in their heterogenous anatomy. Severe defects recognized on prenatal ultrasound screening and/or triggering symptoms in the neonatal period are particularly hazardous. Despite modern advances in surgical and critical care, neonatal Ebstein anomaly exhibits a perinatal mortality of 45%.¹ Knott-Craig and Boston² have devoted their careers to the care of these children and contributed enormously to our understanding of the best management strategies. Their article concludes that most symptomatic neonates can undergo biventricular repair but the ideal timing for that operation is at age of 3 to 5 months. This marks an important transition away from their prior reports.3, 4, 5, 6, 7

Symptomatic newborn infants fall into 2 major categories: those who need time to transition from fetal life and those who are unable to survive without intervention. The number of newborn infants in each category is relatively equal.⁸ It has been our experience that children who are able to transition and go home have a reasonable-sized true right ventricle (RV) and/or little to no tricuspid regurgitation. They do not usually develop symptoms or require surgical intervention within their first year of life. Conversely, neonates who need intervention often have tenuous pulmonary blood flow and significant right heart distension that compromises left ventricular (LV) filling and outflow via interventricular septal shift. The most appropriate intervention must secure blood flow and eliminate the cause of septal shift.

Admittedly, our group is biased. It has always been our opinion that features inherent to Ebstein anomaly favor initial Starnes palliation. The most relevant are right ventricular myopathy and failed tricuspid valve delamination.⁹ A myopathic RV is unable to effectively overcome the elevated pulmonary vascular resistance and oft-underdeveloped branch pulmonary arteries of symptomatic neonates. Secondarily, thin and attenuated valvular tissue in newborn infants makes any attempt at effective valve repair impractical. Finally, if the valvular tissue cannot be relocated to the true annulus along with a restoration of valvular competency, an atrialized RV remains at risk for distension with subsequent displacement of the interventricular septum toward the LV.

We congratulate the evolution of the management algorithm presented within this article,² but have several critiques based on the limitations outlined above. Primarily, the presence of LV compression must be accounted for. Isolated Blalock-Taussig shunt does not address this problem. There are several areas where it is recommended, but we caution providers to consider the presence of LV compression before committing to an isolated shunt. In addition, the timing recommended for biventricular repair following neonatal palliation is 3 to 5 months. RV myopathy is of important concern in these newborn infants. Although rehabilitation of this ventricle is feasible for future 1.5- or 2-ventricle repairs, it appears to be a process that takes longer than 3 to 5 months.¹⁰ Waiting longer may also allow for a lesser need for bidirectional Glenn. Overall, our field has come a long way since 1991,¹¹ and the future for these children has never been more optimistic.