Automated quantitative evaluation of atrioventricular annular plane systolic excursion in human fetuses.

OBJECTIVES The primary aim of this study was to evaluate the feasibility of measuring fetal atrioventricular plane displacement (AVPD) using an automated analysis software. The secondary objectives were to establish reference ranges for AVPD during the second half of normal pregnancy, assess fetal AVPD in prolonged pregnancies in relation to adverse perinatal outcome and in fetuses with a suspicion of intrauterine growth restriction (IUGR). METHODS The reference population consisted of women with uncomplicated pregnancies at 18-42 weeks of gestation (n=201). The prolonged pregnancy group comprised of women included at ≥ 41+0 weeks of gestation (n=107). In the third cohort, women with singleton fetuses with a suspicion of IUGR defined as an estimated fetal weight 97.5th centile were included (n=35). Cine-loops of four-chamber view of the fetal heart were recorded using color tissue Doppler imaging (cTDI). Regions of interest were placed at the AV-plane and myocardial velocity traces were integrated and automatically analyzed to obtain mitral (MAPSE), septal (SAPSE) and tricuspid annular plane systolic excursion (TAPSE). Gestational age specific reference ranges were constructed and normalized to cardiac size. The correlation between AVPD measurements obtained with cTDI and anatomic M-mode were evaluated and agreement between these two methods was tested using Bland-Altman analysis. The mean z-scores of fetal AVPD in the cohort of prolonged pregnancies were compared between normal and adverse outcome groups, and the mean z-scores of IUGR fetuses were compared with that of the reference population using Mann-Whitney U-test. RESULTS Fetal MAPSE, SAPSE and TAPSE increased with gestational age, but did not change significantly when normalized by cardiac size. The fitted mean was highest for TAPSE followed by SAPSE and MAPSE. There were significant correlations between AVPD measurements obtained by M-mode and cTDI: MAPSE (r=0.64, p<0.001), SAPSE (r=0.72, p<0.001) and TAPSE (r=0.84, p<0.001). The geometric means of ratios between AVPD measured by cTDI and M-mode with 95% limits of agreement were 1.38 (0.84-2.25) for MAPSE, 1.00 (0.72-1.40) for SAPSE and 1.20 (0.92-1.57) for TAPSE. In the prolonged pregnancy group, the mean z-scores ± SD for MAPSE (0.14 ± 0.97), SAPSE (0.09 ± 1.02) and TAPSE (0.15 ± 0.90) did not show any significant difference compared to reference ranges. Twenty-one of 107 (20%) neonates had an adverse perinatal outcome but the AVPD z-scores were not significantly different between the normal and the adverse outcome groups in this cohort. The z-scores ± SD of SAPSE, -0.62 ± 1.07 (p=0.006) and TAPSE -0.60 ± 0.89 (p=0.002) were significantly lower in the IUGR group compared to the normal reference ranges, but the differences were not significant when the values were corrected for cardiac size. The inter-observer CVs for the automated measurement of AVPD were 28.1%, 17.7% and 15.3% and the intra-observer CVs were 33.5%, 15.0% and 17.9% for MAPSE, SAPSE and TAPSE, respectively. CONCLUSIONS This study showed that fetal AVPD can be measured integrating cTDI velocities over several cardiac cycles using an automated analysis software. Potentially, automated analysis of AVPD could help gathering larger data sets to facilitate the use as machine-learning models to study fetal cardiac function. The gestational age associated increase in AVPD is most likely a result of increasing cardiac size as the AVPD normalized by cardiac size did not change significantly between 18-42 weeks. A decrease was seen in TAPSE and SAPSE in IUGR fetuses, but not when corrected for cardiac size. This article is protected by copyright. All rights reserved.