Prescriptive standards of echocardiographic morphometric and functional parameters in uncomplicated monochorionic diamniotic fetuses

Objective To create prescriptive standards of cardiac morphometric and functional parameters in a cohort of uncomplicated monochorionic diamniotic (MCDA) twins. Method Fetal echocardiography was performed in a cohort of uncomplicated monochorionic twin fetuses scanned longitudinally, including comprehensive morphometric and functional parameters, using 2-D imaging, M-mode and conventional Doppler. A multilevel polynomial hierarchical model adjusted by gestational age and estimated fetal weight was used to fit each cardiac parameter. Results The global heart dimensions including the atrial and ventricular areas, the ventricles dimensions and myocardial wall thicknesses and most of the functional parameters, such as the longitudinal myocardial motion and the biventricular cardiac output showed a positive quadratic increment throughout pregnancy. On the other hand, the left ejection fraction, shortening fraction and right fractional area change decreased with gestational age. Scatterplots for the main structural and functional parameters and ratios by gestational age, with mean, 5th, 10th, 90th, and 95th percentiles are provided. Regression equations by estimated fetal weight are also created. Conclusion We provide specific comprehensive echocardiographic prescriptive standards for uncomplicated MCDA twin fetuses following current standardized methodology. The implementation of these charts will potentially help to better identify abnormal cardiovascular parameters associated to monochorionic complications.