Color Tissue Doppler to Analyze Fetal Cardiac Time Intervals: Normal Values and Influence of Sample Gate Size.

PURPOSE: To assess the time intervals of the cardiac cycle in healthy fetuses in the second and third trimester using color tissue Doppler imaging (cTDI) and to evaluate the influence of different sizes of sample gates on time interval values. MATERIALS AND METHODS: Time intervals were measured from the cTDI-derived Doppler waveform using a small and large region of interest (ROI) in healthy fetuses. RESULTS: 40 fetuses were included. The median gestational age at examination was 26 + 1 (range: 20 + 5 - 34 + 5) weeks. The median frame rate was 116/s (100 - 161/s) and the median heart rate 143 (range: 125 - 158) beats per minute (bpm). Using small and large ROIs, the second trimester right ventricular (RV) mean isovolumetric contraction times (ICTs) were 39.8 and 41.4 ms (p = 0.17), the mean ejection times (ETs) were 170.2 and 164.6 ms (p < 0.001), the mean isovolumetric relaxation times (IRTs) were 52.8 and 55.3 ms (p = 0.08), respectively. The left ventricular (LV) mean ICTs were 36.2 and 39.4 ms (p = 0.05), the mean ETs were 167.4 and 164.5 ms (p = 0.013), the mean IRTs were 53.9 and 57.1 ms (p = 0.05), respectively. The third trimester RV mean ICTs were 50.7 and 50.4 ms (p = 0.75), the mean ETs were 172.3 and 181.4 ms (p = 0.49), the mean IRTs were 50.2 and 54.6 ms (p = 0.03); the LV mean ICTs were 45.1 and 46.2 ms (p = 0.35), the mean ETs were 175.2 vs. 172.9 ms (p = 0.29), the mean IRTs were 47.1 and 50.0 ms (p = 0.01), respectively. CONCLUSION: Isovolumetric time intervals can be analyzed precisely and relatively independent of ROI size. In the near future, automatic time interval measurement using ultrasound systems will be feasible and the analysis of fetal myocardial function can become part of the clinical routine.

Endocardial Fibroelastosis of the Left Ventricle Affects Right Ventricular Performance in Fetuses with Hypoplastic Left Heart Syndrome: A Prospective Study Using M-Mode, PW- and Tissue Doppler Techniques.

PURPOSE: Myocardial function (MF) of the systemic right ventricle (RV) influences the postnatal course of neonates with hypoplastic left heart syndrome (HLHS). Our study examines whether the presence of endocardial fibroelastosis of the left ventricle (LV EFE) influences MF of the RV in HLHS fetuses. MATERIALS AND METHODS: A prospective study was conducted including 10 controls (group 1), 10 HLHS fetuses with (group 2) and 10 without LV EFE (group 3) - all matched for gestational age. M-mode was used to assess tricuspid plane systolic excursion (TAPSE) and the shortening fraction (SF). PW-Doppler-derived and PW-TDI-derived velocities were assessed. E/A, E/e', e'/a' ratios and the myocardial performance index (mpi') were calculated. RESULTS: The examination of MF revealed significantly lower s' velocities (p < 0.05) and higher values for SF in group 2 compared to group 3. e'/a' ratio, et' (ejection time), E wave velocity, E/e' and SF showed significantly higher values in group 2 compared to group 1. In group 2 a' velocity increased significantly over gestational age. In group 3 but not in group 2, TAPSE increased during gestation. CONCLUSION: These significant differences in MF between the groups might lend support to the notion of negative ventricular-ventricular interaction in the case of HLHS with LV EFE possibly influencing surgical outcomes.

Fetal colour tissue Doppler imaging (cTDI): biventricular reference ranges for the time segments of the cardiac cycle in second and third trimesters of gestation.

PURPOSE: To construct biventricular reference ranges for isovolumic time intervals (isovolumic contraction time, ICT; isovolumic relaxation time, IRT) and ejection time (ET) for colour tissue Doppler imaging (cTDI) between 15 and 37 weeks' in healthy fetuses. METHODS: This was a prospective multicentre cross-sectional study involving 160 singleton pregnancies between 15 and 37 weeks of gestation, using cTDI. ICT, ET, IRT and myocardial performance index (MPI) were analysed offline using a small region of interest (ROI) within the basal part of the right and left ventricular wall immediately distal to the annulus. Regression analysis was used to determine gestational age-adjusted reference ranges and to construct nomograms for cTDI parameters. RESULTS: Right and left ventricular ICT (p = 0.004 and p < 0.001) and ET (p = 0.011 and p = 0.050) increased, whereas IRT (p = 0.862 and p = 0.067) and MPI (p = 0.476 and p = 0.777) remained constant with gestational age. CONCLUSIONS: This is the first study to evaluate fetal isovolumic time intervals in the second and third trimesters of gestation using cTDI. Normal data for fetal isovolumic time intervals and biventricular MPI by colour tissue Doppler imaging are provided. The reference ranges may be useful in research or clinical studies and can be used in fetuses with compromised cardiac function.