Fetal cardiac filling and ejection time fractions by pulsed-wave Doppler: reference ranges and potential clinical application

Understanding the hemodynamic changes in fetuses with coarctation of the aorta using a lumped model of fetal circulation

Coarctation of the aorta (CoA) is a common congenital heart defect characterized by aortic narrowing. Prenatally, it has mild hemodynamic effects as right ventricular disproportion and ductus arteriosus (DA) dilation occur as adaptive mechanisms, but their impact on CoA hemodynamics remains poorly understood. To investigate this, we built a closed 0D computational model of fetal circulation and simulated different CoA cardiovascular remodeling patterns, including aortic isthmus (AoI) narrowing, ventricular disproportion, and DA dilation. Our results showed mild AoI narrowing (80% of reference diameter) required up to 1.7 right/left ventricular end-diastolic volume ratio and 115% DA dilation to maintain physiological pressures, wall shear stresses, and organ perfusion. In contrast, severe narrowing (20% of reference AoI diameter) required up to 5 right/left ventricular end-diastolic volume ratio and 125% DA dilation, highlighting the necessity of co-occurrence of prenatal ventricular disproportion and DA dilation to compensate for AoI narrowing. These physiological regions were validated with ultrasonographic measurements from 7 controls and 9 CoA patients. We compared blood pressures, velocities, and volumetric flow rates across different fetoplacental anatomical sites. AoI velocity showed a delayed retrograde flow peak and increased antegrade diastolic velocity with greater AoI narrowing, which may aid in diagnosing CoA. Minimal differences were observed in other velocities and pressures. Volumetric flow rates across varying degrees of AoI narrowing decreased in the AoI and mitral and aortic valves, remained stable in the middle cerebral and umbilical arteries, and increased in the DA and tricuspid and pulmonary valves. Therefore, we corroborated that in fetal CoA a redistribution of blood flow occurs to ensure perfusion of the brain and placenta, without a significant alteration in fetal hemodynamics (blood pressure and velocities) except for increased diastolic velocities in the AoI.

Sensitive detection of hemodynamic changes after fetoscopic laser photocoagulation by assessing intraventricular pressure difference in fetuses with twin-to-twin transfusion syndrome

OBJECTIVES

To assess the hemodynamics of twin-to-twin transfusion syndrome (TTTS), we measured the intraventricular pressure difference (IVPD), a sensitive marker of myocardial diastolic function, using fetal echocardiography.

METHODS

We included 28 monochorionic diamniotic (MD) twins diagnosed with TTTS who underwent fetoscopic laser photocoagulation (FLP) between 2018 and 2022. Color M-mode Doppler images of both cardiac ventricles were obtained before and after FLP. According to this evaluation, the IVPDs were divided into three groups; those with total, basal, and mid-apical IVPD.

RESULTS

Of the 28 twins, 21 were available for analysis (including eight, eight, three, and two cases in stages Quintero Ⅰ, Ⅱ, Ⅲd, and Ⅲr, respectively). Comparing the pre and postFLP results, significant increases in total and mid-apical IVPD in the left ventricle (LV) of recipient twins were noted (total and mid-apical IVPD: p=0.026 and 0.013, respectively). In the LV of the donor twins, all IVPDs were significantly increased after FLP (total, basal, and mid-apical IVPD: p=0.003, 0.001, and 0.022, respectively). In addition, comparisons between the donor and recipient groups did not show significant differences in either ventricle before FLP.

CONCLUSIONS

IVPD detected subtle hemodynamics changes, such as volume overload and diastolic dysfunction in TTTS before and after FLP. Therefore, IVPD may be a useful marker for monitoring myocardial diastolic function in TTTS.

An intelligent quantification system for fetal heart rhythm assessment: A multicenter prospective study

BACKGROUND

The motion relationship and time intervals of the pulsed-wave Doppler (PWD) spectrum are essential for diagnosing fetal arrhythmia. However, few technologies currently are available to automatically calculate fetal cardiac time intervals (CTIs).

OBJECTIVE

The purpose of this study was to develop a fetal heart rhythm intelligent quantification system (HR-IQS) for the automatic extraction of CTIs and establish the normal reference range for fetal CTIs.

METHODS

A total of 6498 PWD spectrums of 2630 fetuses over the junction between the left ventricular inflow and outflow tracts were recorded across 14 centers. E, A, and V waves were manually labeled by 3 experienced fetal cardiologists, with 17 CTIs extracted. Five-fold cross-validation was performed for training and testing of the deep learning model. Agreement between the manual and HR-IQS-based values was evaluated using the intraclass correlation coefficient and Spearman's rank correlation coefficient. The Jarque-Bera test was applied to evaluate the normality of CTIs' distributions, and the normal reference range of 17 CTIs was established with quantile regression. Arrhythmia subset was compared with the non-arrhythmia subset using the Mann-Whitney U test.

RESULTS

Significant positive correlation (P <.001) and moderate-to-excellent consistency (P <.001) between the manual and HR-IQS automated measurements of CTIs was found. The distribution of CTIs was non-normal (P <.001). The normal range (2.5th to 97.5th percentiles) was successfully established for the 17 CTIs.

CONCLUSIONS

Using our HR-IQS is feasible for the automated calculation of CTIs in practice and thus could provide a promising tool for the assessment of fetal rhythm and function.

Assessment of fetal cardiac function in early fetal life: feasibility, reproducibility, and early fetal nomograms

BACKGROUND

Fetal cardiology has shown a rapid development in the past decades. Fetal echocardiography is not only used for the detection of structural anomalies but also to assess fetal cardiac function. Assessment of the fetal cardiac function is performed mostly in the second and third trimesters. The study of fetal cardiac function at the end of first trimester has not been investigated properly, and there is a lack of reference values at early gestational weeks.

OBJECTIVE

This study aimed to assess if the measurement of time-related parameters of cardiac function in the left ventricle of the fetal heart is feasible and reproducible at the end of the first trimester. If possible, we provide nomograms of these parameters from 11 to 13+6 gestational weeks.

STUDY DESIGN

We conducted a prospective observational study from March to September 2022. The study was carried out in 2 hospitals (Hospital Universitari Dexeus, Barcelona, and Hospital VITAHS 9 Octubre, Valencia, Spain). The scans were performed by 3 specialists in fetal medicine. The exclusion criteria were fetal cardiac rhythm abnormalities, abnormal nuchal translucency, abnormal ductus venosus, fetal malformations, stillbirth, estimated fetal weight <10 percentile, diabetes, and gestational hypertensive disorders. The cardiac function parameters studied in the left ventricle were isovolumetric contraction time, isovolumetric relaxation time, ejection time, filling time, cycle time, myocardial performance index, ejection time fraction, and filling time fraction. We study the feasibility and intra- and interobserver reproducibility of these parameters using the interclass correlation coefficient. Nomograms were created and the percentiles of the values of the different parameters were calculated.

RESULTS

A total of 409 cases were recruited but only 296 could be included in the statistical analysis once the exclusion criteria were applied. The intraobserver reproducibility study was excellent (interclass correlation coefficient >0.900), and the interobserver reproducibility study was good (interclass correlation coefficient >0.700). The data regression analysis showed that cycle time, filling time, isovolumetric contraction time, and filling time fraction increased with gestational age, whereas ejection time fraction decreased with gestational age and myocardial performance index (mean, 0.43±0.08), isovolumetric relaxation time (mean, 0.04±0.01), and ejection time (mean, 0.16±0.01) remained constant from 11 to 13 weeks.

CONCLUSION

The study of fetal cardiac function is feasible and reproducible at 11 to 13+6 gestational weeks. Nomograms of the studied parameters are provided.

Fetal Cardiac Inflow Characteristics in Response to Fetal Anemia: Based on Fetal Hemoglobin Bart's Disease at Mid-Pregnancy

OBJECTIVES

To identify the inflow (filling time fraction [FTF] and E/A ratio) characteristics of fetuses with anemia, and to evaluate the performance of the inflow markers in predicting the affected fetuses.

METHODS

Fetuses at risk of hemoglobin (Hb) Bart's disease at 17-22 weeks were prospectively recruited to undergo echocardiography before diagnostic cordocentesis. Cardiac Doppler images were digitally stored for off-line blinded measurements of FTF and E/A ratio.

RESULTS

A total of 428 fetuses at risk of Hb Bart's disease were analyzed, including 88 affected fetuses (20.6%). The mean gestational age at the time of diagnosis was 19.43 ± 1.5 weeks. The FTFs in both sides were significantly lower in the affected fetuses, whereas the E/A ratios of both sides were significantly higher in the affected group. According to the receiver operating characteristic curves, the performance of the FTF of the right side in predicting affected fetuses was slightly better than that of the left side (area under curve: 0.707 versus 0.680, P < .001). Likewise, the performance of the E/A ratio of the tricuspid valve was slightly better than that of the mitral valve. Also, FTF was superior to E/A ratio in predicting the affected fetuses.

CONCLUSIONS

New insights leading to a better understanding of the fetal cardiac response to anemia are: 1) the FTFs in both sides were significantly decreased, suggesting some degree of diastolic ventricular dysfunction; 2) the E/A ratios of both sides were significantly increased, indicating volume load; and 3) The inflow parameters may be useful as a new predictor of fetal anemia, especially among pregnancies at risk.

Prenatal Diagnosis of Fetal Heart Failure

Fetal heart failure (FHF) is a condition of inability of the fetal heart to deliver adequate blood flow for tissue perfusion in various organs, especially the brain, heart, liver and kidneys. FHF is associated with inadequate cardiac output, which is commonly encountered as the final outcome of several disorders and may lead to intrauterine fetal death or severe morbidity. Fetal echocardiography plays an important role in diagnosis of FHF as well as of the underlying causes. The main findings supporting the diagnosis of FHF include various signs of cardiac dysfunction, such as cardiomegaly, poor contractility, low cardiac output, increased central venous pressures, hydropic signs, and the findings of specific underlying disorders. This review will present a summary of the pathophysiology of fetal cardiac failure and practical points in fetal echocardiography for diagnosis of FHF, focusing on essential diagnostic techniques used in daily practice for evaluation of fetal cardiac function, such as myocardial performance index, arterial and systemic venous Doppler waveforms, shortening fraction, and cardiovascular profile score (CVPs), a combination of five echocardiographic markers indicative of fetal cardiovascular health. The common causes of FHF are reviewed and updated in detail, including fetal dysrhythmia, fetal anemia (e.g., alpha-thalassemia, parvovirus B19 infection, and twin anemia-polycythemia sequence), non-anemic volume load (e.g., twin-to-twin transfusion, arteriovenous malformations, and sacrococcygeal teratoma, etc.), increased afterload (intrauterine growth restriction and outflow tract obstruction, such as critical aortic stenosis), intrinsic myocardial disease (cardiomyopathies), congenital heart defects (Ebstein anomaly, hypoplastic heart, pulmonary stenosis with intact interventricular septum, etc.) and external cardiac compression. Understanding the pathophysiology and clinical courses of various etiologies of FHF can help physicians make prenatal diagnoses and serve as a guide for counseling, surveillance and management.

Cardiac remodeling from the fetus to adulthood

Prenatal cardiac remodeling refers to in utero changes in the fetal heart that occur as a response to an adverse intrauterine environment. In this article, we will review the main mechanisms leading to cardiac remodeling and dysfunction, summarizing and describing the major pathological conditions that have been reported to be related to this in utero plastic adaptive process. We will also recap the current evidence regarding the persistence of fetal cardiac remodeling and dysfunction, both in infancy and later in adult life. Moreover, we will discuss primary, secondary, and tertiary preventive measures and future clinical and research aspects.

Effect of oval foramen restriction and premature contraction of the arterial catheter on right heart function of fetuses and infants

OBJECTIVE

The effect of fetal oval foramen restriction and premature contraction of the arterial catheter for the right heart function of fetuses and infants was studied by evaluating the right and left ventricular (RV/LV) ratios, the tricuspid annular plane systolic excursion (TAPSE) value, and the Tei index of right heart function parameters.

METHODS

This study was approved by the Ethics Committee of First Affiliated Hospital of Hebei North University (K20190116). We collected 257 fetuses between March 2020 and December 2021. Among these, 98 fetuses that did not have any heart abnormalities were assigned to group A, 91 fetuses with restriction of the left and right atrial channels were assigned to group B, and 68 fetuses with premature contraction of the arterial catheter were assigned to group C. The ventricular transverse diameter, the right heart TAPSE value and the Tei index of fetuses in late pregnancy and 90 days after birth were measured in the three groups, and the diagnostic value of each index for the right heart function injury was evaluated. P < 0.05 indicates significant.

RESULTS

The P-value of the TAPSE value and Tei index of infants in BC and AC groups and postnatal infants were less than 0.05, which was significant. In the BC group, the RV/LV ratio of fetuses was compared when P > 0.05, which was not significant; however, P < 0.05 after birth was considered significant. For fetuses and postnatal infants in the BC group, the RV/LV ratio was negatively associated with the TAPSE value. However, it was positively associated with the Tei index; Diagnostic test results. To predict impaired right heart function after birth, TAPSE had low diagnostic value, RV/LV and Tei index had high diagnostic value.

CONCLUSIONS

Oval foramen restriction and premature contraction of the arterial catheter may affect the right heart function after birth and be related to the degree of the right heart enlargement. Although TAPSE prediction of the fetal and postnatal right heart function is limited, the RV/LV ratio and the Tei index can be used to predict impaired right heart function after birth.

Cord Blood Cardiovascular Biomarkers in Left-Sided Congenital Heart Disease

Fetal echocardiography has limited prognostic ability in the evaluation of left-sided congenital heart defects (left heart defects). Cord blood cardiovascular biomarkers could improve the prognostic evaluation of left heart defects. A multicenter prospective cohort (2013−2019) including fetuses with left heart defects (aortic coarctation, aortic stenosis, hypoplastic left heart, and multilevel obstruction (complex left heart defects) subdivided according to their outcome (favorable vs. poor), and control fetuses were evaluated in the third trimester of pregnancy at three referral centers in Spain. Poor outcome was defined as univentricular palliation, heart transplant, or death. Cord blood concentrations of N-terminal precursor of B-type natriuretic peptide, Troponin I, transforming growth factor β, placental growth factor, and soluble fms-like tyrosine kinase-1 were determined. A total of 45 fetuses with left heart defects (29 favorable and 16 poor outcomes) and 35 normal fetuses were included, with a median follow-up of 3.1 years (interquartile range 1.4−3.9). Left heart defects with favorable outcome showed markedly increased cord blood transforming growth factor β (normal heart median 15.5 ng/mL (6.8−21.4) vs. favorable outcome 51.7 ng/mL (13.8−73.9) vs. poor outcome 25.1 ng/mL (6.9−39.0), p = 0.001) and decreased placental growth factor concentrations (normal heart 17.9 pg/mL (13.8−23.9) vs. favorable outcome 12.8 pg/mL (11.7−13.6) vs. poor outcome 11.0 pg/mL (8.8−15.4), p < 0.001). Poor outcome left heart defects had higher N-terminal precursor of B-type natriuretic peptide (normal heart 508.0 pg/mL (287.5−776.3) vs. favorable outcome 617.0 pg/mL (389.8−1087.8) vs. poor outcome 1450.0 pg/mL (919.0−1645.0), p = 0.001) and drastically reduced soluble fms-like tyrosine kinase-1 concentrations (normal heart 1929.7 pg/mL (1364.3−2715.8) vs. favorable outcome (1848.3 pg/mL (646.9−2313.6) vs. poor outcome 259.0 pg/mL (182.0−606.0), p < 0.001). Results showed that fetuses with left heart defects present a distinct cord blood biomarker profile according to their outcome.

Reference ranges for fetal cardiac, ventricular and atrial relative size, sphericity, ventricular dominance, wall asymmetry and relative wall thickness from 18 to 41 gestational weeks

OBJECTIVE

To construct nomograms for fetal cardiac, ventricular and atrial relative size and geometry parameters from 18 to 41 weeks' gestation using a low-risk population of singleton pregnancies.

METHODS

This was a prospective cohort study of 602 low-risk singleton pregnancies undergoing comprehensive fetal echocardiography, from 18 to 41 weeks of gestation, to assess fetal cardiac, atrial and ventricular relative size and sphericity, ventricular dominance, wall asymmetry and relative wall thickness. Intra- and interobserver measurement reproducibility was evaluated using intraclass correlation coefficients (ICC). In order to construct reference ranges across pregnancy, parametric regressions were tested to model each measurement against gestational age and estimated fetal weight. The measurements evaluated were: cardiothoracic ratio; atrial-to-heart area ratios; ventricular-to-heart area ratios; cardiac, ventricular and atrial sphericity indices; right-to-left basal and midventricular ratios; septal-to-free wall thickness ratios; and relative wall thickness.

RESULTS

Fetal cardiac, ventricular and atrial morphometry for assessing relative size and geometry could be successfully performed in > 95% of the population, with moderate-to-excellent interobserver reproducibility (ICC, 0.623-0.907) and good-to-excellent intraobserver reproducibility (ICC, 0.787-0.938). Cardiothoracic ratio and ventricular right-to-left ratio showed a modest increase throughout gestation. Atrial-to-heart and ventricular-to-heart area ratios, atrial sphericity indices and septal-to-free wall thickness ratios were constant with gestational age. Left and right ventricular basal sphericity indices showed a tendency to decrease at the end of gestation, while left and right midventricular sphericity indices tended to decrease in the second trimester. The cardiac sphericity index and left and right relative wall thickness showed a modest decrease with gestational age. Nomograms across gestation were constructed for all echocardiographic parameters described.

CONCLUSIONS

The assessment of cardiac, ventricular and atrial relative size and geometry is feasible and reproducible in the fetus. We provide standardized reference ranges for these parameters throughout gestation, enabling the accurate assessment of cardiac remodeling patterns during fetal life. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.