Measurement of atrioventricular annular plane displacement has been revived: will it prove to be useful in assessing fetal cardiac function?

Advances in the Application of Artificial Intelligence in Fetal Echocardiography

Congenital heart disease is a severe health risk for newborns. Early detection of abnormalities in fetal cardiac structure and function during pregnancy can help patients seek timely diagnostic and therapeutic advice, and early intervention planning can significantly improve fetal survival rates. Echocardiography is one of the most accessible and widely used diagnostic tools in the diagnosis of fetal congenital heart disease. However, traditional fetal echocardiography has limitations due to fetal, maternal, and ultrasound equipment factors and is highly dependent on the skill level of the operator. Artificial intelligence (AI) technology, with its rapid development utilizing advanced computer algorithms, has great potential to empower sonographers in time-saving and accurate diagnosis and to bridge the skill gap in different regions. In recent years, AI-assisted fetal echocardiography has been successfully applied to a wide range of ultrasound diagnoses. This review systematically reviews the applications of AI in the field of fetal echocardiography over the years in terms of image processing, biometrics, and disease diagnosis and provides an outlook for future research.

Automated quantitative evaluation of fetal atrioventricular annular plane systolic excursion before and after intrauterine blood transfusion in pregnancies affected by red blood cell alloimmunization

INTRODUCTION

Maternal red blood cell alloimmunization during pregnancy can lead to hemolysis and various degrees of fetal anemia, which can be treated with intrauterine blood transfusion (IUT) to prevent adverse outcomes. Knowledge about fetal myocardial function and adaptation is limited. The aim of the present study was to measure fetal atrioventricular plane displacement before and after IUT and compare these measurements with previously established reference ranges.

MATERIAL AND METHODS

An observational study was conducted on pregnant women affected by red blood cell alloimmunization. Fetal echocardiography was performed before and after IUT. The atrioventricular plane displacement of the left and right ventricular walls and interventricular septum, described as mitral, septal, and tricuspid annular plane systolic excursion (MAPSE, SAPSE, and TAPSE, respectively), was assessed using color tissue Doppler imaging with automated analysis software. A Mann-Whitney U test was used to compare the z scores to the normal mean before and after IUT.

RESULTS

Twenty-seven fetuses were included. The mean z score for pre-IUT MAPSE was significantly increased compared with the reference ranges, +0.46 (95% confidence interval [CI] +0.17 to +0.75; p = 0.039), while the mean z scores for post-IUT SAPSE and TAPSE were significantly decreased, -0.65 (95% CI -1.11 to -0.19; p < 0.001) and -0.60 (95% CI -1.04 to -0.17; p = 0.003), respectively. The difference in atrioventricular plane displacement z scores before and after IUT was statistically significant in all three locations. The median difference between the pre-IUT and post-IUT z scores was -0.66 (95% CI -1.03 to -0.33, p < 0.001) for MAPSE, -1.05 (95% CI -1.43 to -0.61, p < 0.001) for SAPSE, and -0.60 (95% CI -1.19 to -0.01, p = 0.046) for TAPSE.

CONCLUSIONS

This study suggests that atrioventricular plane displacement, when determined using automated analysis software, may represent a quantitative parameter, describing fetal myocardial function and adaptation before and after IUT.

Automated quantitative evaluation of fetal atrioventricular annular plane systolic excursion

OBJECTIVES

The primary aim of this study was to evaluate the feasibility of automated measurement of fetal atrioventricular (AV) plane displacement (AVPD) over several cardiac cycles using myocardial velocity traces obtained by color tissue Doppler imaging (cTDI). The secondary objectives were to establish reference ranges for AVPD during the second half of normal pregnancy, to assess fetal AVPD in prolonged pregnancy in relation to adverse perinatal outcome and to evaluate AVPD in fetuses with a suspicion of intrauterine growth restriction (IUGR).

METHODS

The population used to develop the reference ranges consisted of women with an uncomplicated singleton pregnancy at 18-42 weeks of gestation (n = 201). The prolonged-pregnancy group comprised women with an uncomplicated singleton pregnancy at ≥ 41 + 0 weeks of gestation (n = 107). The third study cohort comprised women with a singleton pregnancy and suspicion of IUGR, defined as an estimated fetal weight < 2.5^th centile or an estimated fetal weight < 10^th centile and umbilical artery pulsatility index > 97.5^th centile (n = 35). Cineloops of the four-chamber view of the fetal heart were recorded using cTDI. Regions of interest were placed at the AV plane in the left and right ventricular walls and the interventricular septum, and myocardial velocity traces were integrated and analyzed using an automated algorithm developed in-house to obtain mitral (MAPSE), tricuspid (TAPSE) and septal (SAPSE) annular plane systolic excursion. Gestational-age specific reference ranges were constructed and normalized for cardiac size. The correlation between AVPD measurements obtained using cTDI and those obtained by anatomic M-mode were evaluated, and agreement between these two methods was assessed using Bland-Altman analysis. The mean Z-scores of fetal AVPD in the cohort of prolonged pregnancies were compared between cases with normal and those with adverse outcome using Mann-Whitney U-test. The mean Z-scores of fetal AVPD in IUGR fetuses were compared with those in the normal reference population using Mann-Whitney U-test. Inter- and intraobserver variability for acquisition of cTDI recordings and offline analysis was assessed by calculating coefficients of variation (CV) using the root mean square method.

RESULTS

Fetal MAPSE, SAPSE and TAPSE increased with gestational age but did not change significantly when normalized for cardiac size. The fitted mean was highest for TAPSE throughout the second half of gestation, followed by SAPSE and MAPSE. There was a significant correlation between MAPSE (r = 0.64; P < 0.001), SAPSE (r = 0.72; P < 0.001) and TAPSE (r = 0.84; P < 0.001) measurements obtained by M-mode and those obtained by cTDI. The geometric means of ratios between AVPD measured by cTDI and by M-mode were 1.38 (95% limits of agreement (LoA), 0.84-2.25) for MAPSE, 1.00 (95% LoA, 0.72-1.40) for SAPSE and 1.20 (95% LoA, 0.92-1.57) for TAPSE. In the prolonged-pregnancy group, the mean ± SD Z-scores 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 the reference ranges. Twenty-one of the 107 (19.6%) prolonged pregnancies had adverse perinatal outcome. The AVPD Z-scores were not significantly different between pregnancies with normal and those with adverse outcome in the prolonged-pregnancy cohort. The mean ± SD Z-scores for 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 those in the normal reference population, but the differences were not significant when the values were corrected for cardiac size. The interobserver CVs for the automated measurement of MAPSE, SAPSE and TAPSE were 28.1%, 17.7% and 15.3%, respectively, and the respective intraobserver CVs were 33.5%, 15.0% and 17.9%.

CONCLUSIONS

This study showed that fetal AVPD can be measured automatically by integrating cTDI velocities over several cardiac cycles. Automated analysis of AVPD could potentially help gather larger datasets to facilitate use of 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 for cardiac size did not change significantly between 18 and 42 weeks. A decrease was seen in TAPSE and SAPSE in IUGR fetuses, but not after correction for cardiac size. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Longitudinal Reference Ranges for Tricuspid Annular Plane Systolic Excursion and Mitral Annular Plane Systolic Excursion in Normally Grown Fetuses

OBJECTIVES

The aim of this study was to construct reference ranges for fetal tricuspid annular plane systolic excursion (TAPSE) and mitral annular plane systolic excursion (MAPSE) using conventional M-mode ultrasound (US) in the second half of pregnancy.

METHODS

Participants underwent US scans every 4 weeks from 18 weeks' gestation until delivery. The TAPSE and MAPSE were measured by conventional M-mode US at each examination. The relationships between TAPSE and MAPSE and gestational age and estimated fetal weight were modeled by Bayesian mixed effects linear regression.

RESULTS

Positive linear relationships were observed between both MAPSE and TAPSE and gestational age and estimated fetal weight. Reference centiles for TAPSE and MAPSE were developed.

CONCLUSIONS

This simple technique is a useful tool for assessing cardiac function and could be used for quantitative assessments of fetal cardiac function, particularly in high-risk pregnancies such as those complicated by maternal diabetes.

Agreement between anatomical M-mode and tissue Doppler imaging in the assessment of fetal atrioventricular annular plane displacement in uncomplicated pregnancies: A prospective longitudinal study

AIM

To evaluate the level of agreement between M-mode and pulsed-wave tissue Doppler imaging (PW-TDI) techniques in assessing fetal mitral annular plane systolic excursion (MAPSE), tricuspid annular plane systolic excursion (TAPSE) and septal annular plane systolic excursion (SAPSE) in a low-risk population.

METHODS

This prospective longitudinal study included healthy fetuses assessed from 18 to 40 weeks of gestation. Tricuspid annular plane systolic excursion, MAPSE and SAPSE were measured using anatomical M-mode and PW-TDI. The agreement between the two diagnostic tests was assessed using Bland-Altman analysis.

RESULTS

Fifty fetuses were included in the final analysis. Mean values of TASPE were higher than that of MAPSE. There was a progressive increase of TAPSE, MAPSE and SAPSE values with advancing gestation. For each parameter assessed, there was an overall good agreement between the measurements obtained with M-mode and PW-TDI techniques. However, the measurements made with M-mode were slightly higher than those obtained with PW-TDI (mean differences: 0.03, 0.05 and 0.03 cm for TAPSE, MAPSE and SAPSE, respectively). When stratifying the analyses by gestational age, the mean values of TAPSE, MAPSE and SAPSE measured with M-Mode were higher compared to those obtained with PW-TDI, although the mean differences between the two techniques tended to narrow with increasing gestation. Tricuspid annular plane systolic excursion, MAPSE and SAPSE measurements were all significantly, positively associated with gestational age (all P < 0.001).

CONCLUSION

Fetal atrioventricular annular plane displacement can be assessed with M-mode technique, or with PW-TDI as the velocity-time integral of the myocardial systolic waveform. Atrioventricular annular plane displacement values obtained with M-mode technique are slightly higher than those obtained with PW-TDI.

How to Acquire Cardiac Volumes for Sonographic Examination of the Fetal Heart: Part 2

The effective performance of fetal cardiac examination using spatiotemporal image correlation (STIC) technology requires 2 essential steps: volume acquisition and postprocessing. An important prerequisite is training sonologists to acquire high-quality volume data sets so that when analyzed, such volumes are informative. This article is part 2 of a series on 4-dimensional sonography with STIC. Part 1 focused on STIC technology and its features, the importance of operator training/experience and acquisition of high-quality STIC volumes, factors that affect STIC volume acquisition rates, and general recommendations on performing 4D sonography with STIC. In part 2, we discuss a detailed and practical stepwise approach for STIC volume acquisition, along with methods to determine whether such volumes are appropriate for analysis.