Prelabour myocardial deformation and cardiac output in fetuses that develop intrapartum compromise at term: a prospective observational study

Myocardial strain assessment in the human fetus by cardiac MRI using Doppler ultrasound gating and feature tracking

OBJECTIVES

Assessment of myocardial strain by feature tracking magnetic resonance imaging (FT-MRI) in human fetuses with and without congenital heart disease (CHD) using cardiac Doppler ultrasound (DUS) gating.

METHODS

A total of 43 human fetuses (gestational age 28-41 weeks) underwent dynamic cardiac MRI at 3 T. Cine balanced steady-state free-precession imaging was performed using fetal cardiac DUS gating. FT-MRI was analyzed using dedicated post-processing software. Endo- and epicardial contours were manually delineated from fetal cardiac 4-chamber views, followed by automated propagation to calculate global longitudinal strain (GLS) of the left (LV) and right ventricle (RV), LV radial strain, and LV strain rate.

RESULTS

Strain assessment was successful in 38/43 fetuses (88%); 23 of them had postnatally confirmed diagnosis of CHD (e.g., coarctation, transposition of great arteries) and 15 were heart healthy. Five fetuses were excluded due to reduced image quality. In fetuses with CHD compared to healthy controls, median LV GLS (- 13.2% vs. - 18.9%; p < 0.007), RV GLS (- 7.9% vs. - 16.2%; p < 0.006), and LV strain rate (1.4 s-1 vs. 1.6 s-1; p < 0.003) were significantly higher (i.e., less negative). LV radial strain was without a statistically significant difference (20.7% vs. 22.6%; p = 0.1). Bivariate discriminant analysis for LV GLS and RV GLS revealed a sensitivity of 67% and specificity of 93% to differentiate between fetuses with CHD and healthy fetuses.

CONCLUSION

Myocardial strain was successfully assessed in the human fetus, performing dynamic fetal cardiac MRI with DUS gating. Our study indicates that strain parameters may allow for differentiation between fetuses with and without CHD.

CLINICAL RELEVANCE STATEMENT

Myocardial strain analysis by cardiac MRI with Doppler ultrasound gating and feature tracking may provide a new diagnostic approach for evaluation of fetal cardiac function in congenital heart disease.

KEY POINTS

• MRI myocardial strain analysis has not been performed in human fetuses so far. • Myocardial strain was assessed in human fetuses using cardiac MRI with Doppler ultrasound gating. • MRI myocardial strain may provide a new diagnostic approach to evaluate fetal cardiac function.

Sleep in the Supine Position during Pregnancy Is Associated with Fetal Cerebral Redistribution

The supine sleep position in late pregnancy is a major risk factor for stillbirth, with a population attributable risk of 5.8% and one in four pregnant women reportedly sleeping in a supine position. Although the mechanisms linking the supine sleep position and late stillbirth remain unclear, there is evidence that it exacerbates pre-existing maternal sleep disordered breathing, which is another known risk factor for adverse perinatal outcomes. Given that maternal sleep position is a potentially modifiable risk factor, the aim of this study was to characterize and correlate uteroplacental and fetal hemodynamics, including cardiac function, in a cohort of women with apparently uncomplicated pregnancies with their nocturnal sleep position. This was a prospective observational cohort study at an Australian tertiary obstetric hospital. Women were asked to complete a series of questions related to their sleep position in late pregnancy after 35 weeks of completed gestation. They also underwent an ultrasound assessment where Doppler indices of various fetoplacental vessels and fetal cardiac function were measured. Regional cerebral perfusion was also assessed. Pregnancy outcome data was extracted from the electronic hospital database for analysis. A total of 274 women were included in the final analysis. Of these, 78.1% (214/274) reported no supine sleep, and 21.9% (60/274) reported going to sleep in a supine position. The middle cerebral artery, anterior cerebral artery, and vertebral artery pulsatility indices were all significantly lower in the supine sleep cohort, as was the cerebroplacental ratio. There were no significant differences in the mode or indication for delivery or in serious neonatal outcomes, including 5-min Apgar score < 7, acidosis, and neonatal intensive care unit admission between cohorts. Women in the supine cohort were more likely to have an infant with a BW > 90th centile (p = 0.04). This data demonstrates fetal brain sparing in association with the maternal supine sleep position in a low-risk population. This data contributes to the growing body of literature attempting to elucidate the etiological pathways responsible for the association of late stillbirth with the maternal supine sleep position.

Feto-placental Dopplers are not altered in women with obstructive sleep apnoea symptoms

BACKGROUND

Snoring, gasping or choking during sleep are common symptoms of sleep-disordered breathing and are associated with multiple adverse maternal and obstetric outcomes. The mechanisms responsible remain unknown; however, placental dysfunction is suspected.

AIMS

The aim of this study was to investigate feto-placental and fetal cardiac function in women with pregnancies complicated by obstructive sleep apnoea symptoms.

MATERIALS AND METHODS

This was a prospective observational cohort study at a large tertiary obstetric hospital in Australia. Women were asked to complete a questionnaire relating to the presence and severity of obstructive sleep apnoea symptoms. They also underwent an ultrasound scan where Doppler indices of various feto-placental vessels and fetal cardiac function were measured. Regional cerebral perfusion was also assessed.

RESULTS

A total of 255 women were included in the final analysis. Of these, 36.1% (92/255) of women reported no obstructive sleep apnoea symptoms; 63.9% (163/255) reported they experienced some form of obstructive sleep apnoea symptoms that included any frequency of snoring or choking/gasping, while 42.0% (107/255) complained of severe obstructive sleep apnoea symptoms (snoring ≥ 3 times a week or choking/gasping). There were no significant differences in feto-placental Dopplers or fetal cardiac function parameters in women with obstructive sleep apnoea symptoms. There were also no differences in regional cerebral blood flow between groups, or any correlation with severity of symptoms.

CONCLUSIONS

Our data challenge the current perspective that adverse perinatal outcomes in women with obstructive sleep apnoea symptoms are related primarily to placental dysfunction and fetal compromise.