Fetal colour tissue Doppler imaging (cTDI): biventricular reference ranges for the time segments of the cardiac cycle in second and third trimesters of gestation
BACKGROUND Few studies have investigated the relationship between myocardial tissue Doppler parameters and fetal size adjusted for gestational age and its trend has been controversial. AIMS To investigate fetal cardiac function before birth using tissue Doppler imaging (TDI: indicated by the prime symbol (')) in low-risk term pregnancies by comparing the TDI parameters with gestational age-specific birth weight percentiles and z scores. STUDY DESIGN AND MEASUREMENTS Interventricular septum, left and right ventricular myocardial peak early diastolic (E'), late diastolic (A') and systolic (S') velocities, E'/A' ratios, myocardial performance index (MPI') and umbilical artery pulsatility index were measured within three days before birth in 76 low-risk term pregnancies, including appropriate for gestational age (AGA, n=50), small for gestational age (SGA, n=10), and large for gestational age (LGA, n=16) subjects. RESULTS Myocardial peak velocities showed higher in the LGA and lower in the SGA compared with the AGA group, and All S' positively correlated with birth weight (r=0.51-0.57). All z scores of S' demonstrated a positive correlation with birth weight z score (Spearman r=0.45-0.53). MPI' was significantly higher in the SGA and lower in the LGA compared with the AGA group. All MPI' negatively correlated with birth weight (r=-0.55 to -0.65). All z scores of MPI' showed a negative correlation with birth weight z score (Spearman r=-0.40 to -0.56). CONCLUSIONS Fetal myocardial peak velocities and MPI' physiologically changed in proportion to body size adjusted for gestational age in low-risk term pregnancies.