Left Ventricular End-Systolic Eccentricity Index for Assessment of Pulmonary Hypertension in Infants

Background: Pulmonary hypertension (PH) is a common problem in the neonatal intensive care unit and is associated with significant morbidity and mortality. The aim of this study was to identify a quantitative echocardiographic marker of septal curvature that can be used to accurately identify PH in NICU infants with concern for PH.

Methods: Echocardiograms of infants who were prematurely born and infants with persistent pulmonary hypertension of the newborn were performed using a defined protocol for evaluation of PH. Qualitative assessment by a single pediatric cardiologist was used as a reference standard. Qualitative and quantitative parameters of right ventricular (RV) size, pressure, and function were documented. Left ventricular end-systolic eccentricity index (EI) was defined as the ratio of the anterior-inferior and septal-posterolateral cavity dimensions at the mid-ventricular level.

Results: A total of 216 infants at risk for PH were included in this study. One hundred forty-three (66%) had an interpretable tricuspid regurgitation jet velocity. While systolic septal flattening was recognized at EIs ≥ 1.15, more than half-systemic RV pressure became apparent at EIs ≥ 1.3. Unlike qualitative assessment of septal flattening, there was high inter-observer agreement for EIs. Quantitative parameters of RV systolic function were impaired only at EIs ≥ 1.3.

Conclusions: We suggest that EIs should be incorporated into routine protocols when there is a concern for PH in neonates. This may lead to a more reliable assessment of PH and may reduce inter-observer variability. Correlation of EIs with invasive hemodynamic data is needed to validate our results.