P08.04: The relationship between cardiomegaly and global strain in fetuses with intrauterine growth restriction (IUGR)

Abstract

During the screening examination of the fetal heart cardiomegaly can be identified by computing the area of the 4-chamber view (4CV). The purpose of this study was to compare the relationship between cardiomegaly of the 4CV and global strain of the right (RV) and left (LV) ventricles. 30 fetuses with growth restriction (EFW < 10th centile) were evaluated between 25 and 37 weeks of gestation. The 4CV was identified at end-diastole and the longest basal-apical and transverse lengths were measured, followed by computation of the area. Using previously published criteria, cardiomegaly was defined as an area >90% for the estimated fetal weight (EFW). Global strain was computed using speckle tracking software in which the endocardial length was measured at end-diastole and end-systole from the RV and LV. From these measurements the global strain was computed as follows: [(end-systolic length-end-diastolic length)/end diastolic length) x 100] . Abnormal global strain was defined as values >90th centile derived from Z score computation using data from 200 control fetuses. The mean global strain for the RV was -23 (3.9) and the LV -23 (3.7). Cardiomegaly was present in 46% (14/30) of fetuses with IUGR. Fifty percent of fetuses with cardiomegaly (7/14) had abnormal global strain of the LV, and 64% (9/14) had abnormal global strain of the RV. Abnormal global strain of either the right and/or left ventricles was present in 71% (10/14). A simple method to detect cardiomegaly is to compute the area of the 4CV. If abnormally increased in size, evaluation of global strain of the RV and LV should be considered as it reflects early ventricular dysfunction. While global strain was computed in this study using speckle-tracking software, the end-diastolic and end-systolic endocardial lengths of the ventricular chambers can be measured using generic length measurement software present on most ultrasound machines. From these measurements the global strain can be computed.