Development of the Z-score for the measurement of myocardial thickness by two-dimensional echocardiography in normal fetuses

Abstract

Background: In the current literature, there is a tendency to describe normal values of echocardiographic measurements by means of the Z-score. In fetal cardiology, these Z-score equations are still being established. Measurement of myocardial thickness is an important assessment, especially in fetuses of diabetic mothers, because of the risk of developing myocardial hypertrophy secondary to elevated maternal blood glucose levels.

Objective: To determine the percentiles and to develop the Z-score equations of right and left ventricular lateral walls and interventricular septum measurements using two-dimensional echocardiography in normal fetuses between 24 and 34 weeks of gestation.

Methods: This is a prospective cross-sectional study that was performed in single fetuses with normal heart from nondiabetic pregnant women. Measurements of the lateral walls of the right and left ventricles and the interventricular septum were made.

Results: Eight hundred and seventy three pregnant women were included. We determined the percentiles of the measurements for each gestational age. The Z-score equation was developed for each of the measurements: right ventricular lateral wall measurement [RVLW = x-(-1 + 0.109 * GA)/0.4], left ventricle lateral wall measurement [LVLW = x-(-1.366 + 0.12 * GA)/0.43], and interventricular septum, both at the four-chamber view [IVS_4ch = (x-(-1.113 + 0.107 * GA)/0.4] and at the left ventricular outflow tract plane [IVS_LVOT = (x-(-0.581 + 0.084 * GA)/0.35].

Conclusion: The present study allowed the demonstration of the percentiles and the Z-score equations for each of the measurements studied.

Keywords: echocardiography; fetal echocardiography.