Echocardiographic Left Ventricular Z-Score Utility in Predicting Pulmonary-Systemic Flow Ratio in Children with Ventricular Septal Defect or Patent Ductus Arteriosus

Background: The correlation between the Z-score of the left ventricular (LV) diameter and the LV volume-overload due to pulmonary over-circulation in children with ventricular septal defect (VSD) or patent ductus arteriosus (PDA) remains unclear. Methods and Results: The present, retrospective study enrolled 70 children (aged 0.3–16.8 years; 33 males, 37 females) with a diagnosis of isolated VSD and/or PDA who underwent cardiac catheterization (CC) between 2015 and 2019. Patients with chromosomal/genetic anomalies, growth disorder, right-ventricular enlargement or other conditions causing LV enlargement were excluded. Echocardiographic parameters were retrospectively evaluated from the medical records, converted to a Z-score, then compared with CC data. The pulmonary-systemic flow ratio on CC (cQp/Qs) correlated significantly with the Z-score of both the LV end-diastolic diameter (Zd) (r=0.698, P<0.0001) and LV end-systolic diameter (r=0.593, P<0.0001). Regression analysis and curve-fitting were used to predict the cQp/Qs based on the Zd, and a significant regression equation was found on cubic regression (R² of 0.524, P<0.0001) showing a strong correlation with the cQp/Qs (r=0.724, P<0.0001). Conclusions: The Z-score of the LV diameter can be a useful, non-invasive marker for evaluating LV volume overload and determining the surgical indications in children with VSD or PDA because of its strong correlation with the cQp/Qs.