Left heart hypoplasia in the fetus: Echocardiographic predictors of outcome



Colquitt JL, Loar RW, Bolin EH, Ezon DS, Heinle JS, Morris SA.

Prenat Diagn. 2022 Apr;42(4):447-460. doi: 10.1002/pd.6101. PMID: 35040508


Manoj Gupta

Commentary from Dr. Manoj Gupta (New York City, NY, USA), chief section editor of Pediatric & Fetal Cardiology Journal Watch.


Take Home Points:

  1. Left heart hypoplasia (LHH) with an apex‐forming left ventricle, is a phenotype at risk for neonatal surgical intervention, including single ventricle (SV) palliation in more severe cases; but it is difficult to predict.
  2. Left‐to‐right foramen ovale flow in‐utero predicts need for postnatal arch surgery. The strongest single outcome discriminator was exclusively left‐to‐right flow foramen ovale (FO) flow ≥32 weeks gestational age (GA) (seen in 0% with no surgery, 22% with biventricular surgery, 88% with SV palliation).
  3. At >32 weeks GA, fetuses with right‐to‐left FO flow and aortopulmonary ratio >0.76 had 0% probability of neonatal surgery, while those with left‐to‐right FO flow and mitral valve z‐score < −3.6 had a 70% probability of SV palliation.



A common challenge for fetal care providers is to provide prognostic information for those with a “borderline left heart”, in which there is concern that a newborn may require single ventricle (SV) palliation. The borderline left heart generally presents as one of two phenotypes: (1) Primary valvar aortic stenosis, which is commonly associated with endocardial fibroelastosis, ventricular dysfunction, and an ultimately reduced left ventricular (LV) length, and (2) Left heart hypoplasia (LHH), which is associated with hypoplastic mitral and aortic valve (AV) annuli but with laminar flow, significant aortic arch hypoplasia, and an apex‐forming or near apex‐forming left ventricle with preserved systolic function.



This study demonstrates that (1) fetuses with exclusive right‐to‐left FO flow at either <26 and > 32 weeks do not require SV palliation, and (2) the overall likelihood of a SV outcome is low for this phenotype.

Any left‐to‐right FO (bidirectional or left‐to‐right) flow is an established predictor for neonatal intervention. In a study of fetuses with disproportionately small left ventricles, bidirectional or left‐to‐right FO flow was seen in all patients who required neonatal arch surgery. Any left‐to‐right FO and abnormal aortic arch flow are specific for neonatal intervention but does not identify all fetuses that will need an arch repair as part of a biventricular circulation.



Fetal echocardiographic predictors of postnatal circulation type among fetuses with LHH