Fetal myocardial deformation measured with two-dimensional speckle-tracking echocardiography: longitudinal prospective cohort study of 124 healthy fetuses

OBJECTIVES: Two-dimensional speckle tracking echocardiography (2D-STE) is a relatively new, promising technique to assess cardiac function in the fetus. Fetal cardiac function can be used in the evaluation of non-cardiac disease states in pregnancy. However, reliable reference values for deformation parameters measured with speckle tracking in the fetus are needed before it can be introduced into clinical practice. This study aimed to obtain reference values for fetal global longitudinal strain (GLS) and strain rate (GLSR) measured with 2D-STE and to compare the right ventricle values to those of the left ventricle.

METHODS: In this longitudinal prospective cohort study, echocardiography was performed four weekly from inclusion (18-21 weeks) until delivery to obtain four-chamber loops of the fetal heart. Left and right ventricular GLS and GLSR were measured with 2D-STE at each examination. Using Bayesian mixed-effects models, reference values with a lower and an upper 5% prediction limit during pregnancy were calculated. Right and left ventricular GLS values during pregnancy were compared with a Wilcoxon signed-rank test.

RESULTS: A total of 592 and 566 assessments of GLS and GLSR for the left and right ventricle respectively, were included. Reference values were obtained for both ventricles per gestational age week for the uncomplicated pregnancy in non-anomalous, appropriately grown fetuses. GLS and GLSR values in both ventricles increased (i.e. mathematical less negative) significantly during pregnancy. Right ventricular GLS and GLSR values were significantly higher (i.e. less negative) than the left ventricular values at every gestational age measured.

CONCLUSIONS: Reference values were obtained for fetal GLS and GLSR. GLS and GLSR values increased significantly for both ventricles from the second trimester until delivery, with significantly higher values for the right ventricle compared to the left ventricle. Future studies are needed to assess whether the obtained reference values are helpful in clinical practice in the assessment of pregnancy complications, such as fetal growth restriction or cardiac anomalies. This article is protected by copyright. All rights reserved.