Fetal cardiac assessment
The methodology was described in detail previously (2, 3). Essentially, fetal heart was assessed using Canon Aplio i900 machines equipped with a convex transducer (10C3 and i8CX1). Left and right ventricular sphericity indices were measured on images from an apical 4-chamber view at end-diastole. Left myocardial performance index was obtained using pulsed wave Doppler. Systolic functional assessment included tricuspid annular plane systolic excursion (TAPSE) using M-Mode, isovolumic contraction (IVCT) from Doppler waveforms of blood flow. Diastolic function was assessed with Doppler waveforms of blood flow and tissue Doppler. Measurements included E/A ratio, E/e’, isovolumic relaxation time (IVRT). Myocardial deformation of the left and right ventricle was measured in the apical 4-chamber view. All images were acquired at 100-160 frames per second as per recent guidelines (14) and analysed using special speckle tracking software (Vitrea, Canon) as previously described (3). Global longitudinal strain (GLS) and diastolic peak strain rate (E and A), from the right and left ventricle, were measured.