Fig. 1From: Reference values for fetal Doppler-based cardiocirculatory indices in monochorionic-diamniotic twin pregnancyA Early diastolic filling time measured in ductus venosus Doppler waveforms (DV-E) (S = systolic wave, D = diastolic wave, and a = atrial wave); B Left myocardial performance index (LV-MPI) Doppler waveforms, 1 = mitral valve closure click, 2 = aortic valve opening click, 3 = aortic valve closure click, and 4 = mitral valve opening click (E = peak velocity in early diastole, A = peak velocity in late diastole by atrial contraction)Back to article page