Maternal hyperoxygenation improves left heart filling in fetuses with atrial septal aneurysm causing impediment to left ventricular inflow

Prenatal Diagnosis of Congenital Heart Disease: The Crucial Role of Perinatal and Delivery Planning

Although most congenital heart defects (CHDs) are asymptomatic at birth, certain CHD lesions are at significant risk of severe hemodynamic instability and death if emergent cardiac interventions are not performed in a timely fashion. Therefore, accurate identification of at-risk fetuses and appropriate delivery resource planning according to the degree of anticipated hemodynamic instability is crucial. Fetal echocardiography has increased prenatal CHD detection in recent years due to advancements in ultrasound techniques and improved obstetrical cardiac screening protocols, enabling the prediction of newborns' hemodynamic status. This assessment can guide multidisciplinary resource planning for postnatal care, including selection of delivery site, delivery room management, and transport to a cardiac center based on CHD risk severity. This review will discuss fetal cardiovascular physiology and the circulatory changes that occur at the time of and immediately following birth, outline fetal echocardiographic findings used to risk-stratify newborns with CHDs, and outline principles for neonatal resuscitation and initial transitional care in neonates with these complex CHD lesions.

Fetal cardiac magnetic resonance imaging of the descending aorta in suspected left-sided cardiac obstructions

Background

Severe left-sided cardiac obstructions are associated with high morbidity and mortality if not detected in time. The correct prenatal diagnosis of coarctation of the aorta (CoA) is difficult. Fetal cardiac magnetic resonance imaging (CMR) may improve the prenatal diagnosis of complex congenital heart defects. Flow measurements in the ascending aorta could aid in predicting postnatal CoA, but its accurate visualization is challenging.

Objectives

To compare the flow in the descending aorta (DAo) and umbilical vein (UV) in fetuses with suspected left-sided cardiac obstructions with and without the need for postnatal intervention and healthy controls by fetal phase-contrast CMR flow. A second objective was to determine if adding fetal CMR to echocardiography (echo) improves the fetal CoA diagnosis.

Methods

Prospective fetal CMR phase-contrast flow in the DAo and UV and echo studies were conducted between 2017 and 2022.

Results

A total of 46 fetuses with suspected left-sided cardiac obstructions [11 hypoplastic left heart syndrome (HLHS), five critical aortic stenosis (cAS), and 30 CoA] and five controls were included. Neonatal interventions for left-sided cardiac obstructions (n = 23) or comfort care (n = 1 with HLHS) were pursued in all 16 fetuses with suspected HLHS or cAS and in eight (27%) fetuses with true CoA. DAo or UV flow was not different in fetuses with and without need of intervention. However, DAo and UV flows were lower in fetuses with either retrograde isthmic systolic flow [DAo flow 253 (72) vs. 261 (97) ml/kg/min, p = 0.035; UV flow 113 (75) vs. 161 (81) ml/kg/min, p = 0.04] or with suspected CoA and restrictive atrial septum [DAo flow 200 (71) vs. 268 (94) ml/kg/min, p = 0.04; UV flow 89 vs. 159 (76) ml/kg/min, p = 0.04] as well as in those without these changes. Adding fetal CMR to fetal echo predictors for postnatal CoA did not improve the diagnosis of CoA.

Conclusion

Fetal CMR-derived DAo and UV flow measurements do not improve the prenatal diagnosis of left-sided cardiac obstructions, but they could be important in identifying fetuses with a more severe decrease in blood flow across the left side of the heart. The physiological explanation may be a markedly decreased left ventricular cardiac output with subsequent retrograde systolic isthmic flow and decreased total DAo flow.

Maternal hyperoxygenation during pregnancy as a tool in fetal disease diagnosis and treatment

Maternal hyperoxygenation (MHO) consists of giving pregnant women (60% to 100%) oxygen through a facemask and using ultrasound assess or monitor the influence on fetal cardiovascular circulation. This review discusses the findings and the utility of acute and chronic MHO in various fetal diseases.

Utility of Fetal Echocardiography with Acute Maternal Hyperoxygenation Testing in Assessment of Complex Congenital Heart Defects

Fetal echocardiography is an excellent tool for accurately assessing the anatomy and physiology of most congenital heart defects (CHDs). Knowledge gathered from a thorough initial fetal echocardiogram and serial assessment assists with appropriate perinatal care planning, resulting in improved postnatal outcomes. However, fetal echocardiography alone provides limited information about the status of the pulmonary vasculature, which can be abnormal in certain complex CHDs with obstructed pulmonary venous flow (hypoplastic left heart syndrome with restrictive atrial septum) or excessive pulmonary artery flow (d-transposition of the great arteries, usually with a restrictive ductus arteriosus). Fetuses with these CHDs are at high risk of developing severe hemodynamic instability with the immediate transition from prenatal to postnatal circulatory physiology at the time of birth. Adjunctive use of acute maternal hyperoxygenation (MH) testing in such cases can help determine pulmonary vascular reactivity in prenatal life and better predict the likelihood of postnatal compromise and the need for emergent intervention. This comprehensive review discusses the findings of studies describing acute MH testing in a diverse spectrum of CHDs and congenital diagnoses with pulmonary hypoplasia. We review historical perspectives, safety profile, commonly used clinical protocols, limitations, and future directions of acute MH testing. We also provide practical tips on setting up MH testing in a fetal echocardiography laboratory.

Cross-Sectional Observational Study of Typical in utero Fetal Movements Using Machine Learning

Early variations of fetal movements are the hallmark of a healthy developing central nervous system. However, there are no automatic methods to quantify the complex 3D motion of the developing fetus in utero. The aim of this prospective study was to use machine learning (ML) on in utero MRI to perform quantitative kinematic analysis of fetal limb movement, assessing the impact of maternal, placental, and fetal factors. In this cross-sectional, observational study, we used 76 sets of fetal (24-40 gestational weeks [GW]) blood oxygenation level-dependent (BOLD) MRI scans of 52 women (18-45 years old) during typical pregnancies. Pregnant women were scanned for 5-10 min while breathing room air (21% O2) and for 5-10 min while breathing 100% FiO2 in supine and/or lateral position. BOLD acquisition time was 20 min in total with effective temporal resolution approximately 3 s. To quantify upper and lower limb kinematics, we used a 3D convolutional neural network previously trained to track fetal key points (wrists, elbows, shoulders, ankles, knees, hips) on similar BOLD time series. Tracking was visually assessed, errors were manually corrected, and the absolute movement time (AMT) for each joint was calculated. To identify variables that had a significant association with AMT, we constructed a mixed-model ANOVA with interaction terms. Fetuses showed significantly longer duration of limb movements during maternal hyperoxia. We also found a significant centrifugal increase of AMT across limbs and significantly longer AMT of upper extremities <31 GW and longer AMT of lower extremities >35 GW. In conclusion, using ML we successfully quantified complex 3D fetal limb motion in utero and across gestation, showing maternal factors (hyperoxia) and fetal factors (gestational age, joint) that impact movement. Quantification of fetal motion on MRI is a potential new biomarker of fetal health and neuromuscular development.

The Accelerated Right Ventricular Failure in Fetal Anemia in the Presence of Restrictive Foramen Ovale

Objective: To describe serious hemodynamic changes secondary to anemia in the case of restrictive foramen ovale (FO). Case: A 43-year-old pregnant woman, G4P0030, underwent fetal echocardiography at 35 weeks of gestation and was found to have (1) restrictive FO; (2) poor right ventricular function; (3) unbalanced hemodynamics; (4) fetal anemia (high MCA-PSV and hepatosplenomegaly). Acid-elution test indicated feto-maternal hemorrhage. Cesarean section was performed for postnatal blood transfusion. Nevertheless, the newborn developed heart failure and died after partial blood exchanges. Conclusions: Insights gained from this study are as follows: (1) Restrictive FO in structurally normal hearts can modify fetal response to anemia differently, by unequally distributing blood volume, leading to much more deteriorating right ventricular function. (2) To make decisions for intrauterine or extrauterine treatment in cases of anemia-associated heart failure, several factors must be taken into account such as gestational age, fetal cardiac function, and placental function. Because of the hyperdynamic state of newborns immediately after birth, delivery can deteriorate the compromised heart to irreversible failure. Intrauterine transfusion for a well-prepared heart just before delivery may be the best option since the baby should be well oxygenated at the time of delivery.

Fetal Atrial Septal Aneurysm: Follow-Up from Second to Third Trimester

Atrial septal aneurysm (ASA) is a rarely reported fetal finding. Its definition is variable, but the diagnosis is usually made when the foramen ovale flap extends at least halfway across the left atrium. It is considered a transient, self-limiting condition, but on occasion, it can be complicated by fetal arrhythmia or left ventricular (LV) inflow obstruction—if longstanding, this can lead to left heart hypoplasia. We present two cases of ASA diagnosed at the second trimester scan, one of which was subsequently complicated by LV inflow obstruction and prenatal suspicion of hypoplastic aortic arch. This report is a good illustration of how structure follows function: a small LV preload can lead to a decreased LV output, which in turn will end up in a hypoplastic LV and outflow tract—all this is reversible after birth, due to the physiological circulatory modifications that occur in the newborn.

Fetal aortic coarctation: A combination of third-trimester echocardiographic parameters to improve the prediction of postnatal outcome

OBJECTIVES

This study aims to determine a combination of third-trimester echocardiographic parameters for improving the prenatal prediction of coarctation of the aorta (CoA) after birth.

METHODS

We included all cases of suspected CoA during fetal echocardiography performed in the second and/or third trimester of pregnancy at Gaslini Children's Hospital between January 2010 and December 2020. The last prenatal ultrasound evaluation was reviewed considering most of the echocardiographic criteria were already published for prenatal CoA diagnosis. Associated minor cardiac anomalies, such as a ventricular septal defect, persistent left superior vena cava (PLSCV), and redundant foramen ovale (FO) membrane, as well as postnatal outcomes, were reported. Initial perinatal management was defined based on the risk stratification of CoA during prenatal echocardiography. Neonates were divided into two groups depending on the presence or absence of CoA after birth.

RESULTS

A total of 91 fetuses with CoA suspicion were selected, of which 27 (30%) were confirmed with CoA after birth and underwent surgical repair. All cardiac parameters except redundant FO membrane and PLSCV showed a significant correlation with CoA. Statistical analysis confirmed that cardiovascular disproportion with right predominance carries an increased risk for occurrence of CoA, especially if already evident during the ultrasound evaluation in the second trimester. Aortic valve (AV) z-score and distal transverse aortic arch (TAA) z-score resulted as the best predictors of CoA after birth. The best cutoff point for CoA discrimination with ROC analysis was an AV z-score of -1.25 and a distal TAA z-score of -0.37. A total of 46% of those without CoA were diagnosed with a cardiac defect, which was not diagnosed in utero, pulmonary hypertension, or a genetic syndrome.

CONCLUSION

The current criteria for diagnosing CoA in utero allow accurate diagnosis of most severe cases but the rate of false positives remains relatively high for milder cases. A combination of anatomic and functional echocardiographic parameters might be used in stratifying the risk of CoA. We proposed the AV and the TAA diameter z-scores as the best predictors of CoA after birth. In addition, neonates without CoA deserve proper monitoring at birth because prenatal evidence of a significant cardiovascular discrepancy between the right and left cardiac structures has an inherent risk for additional morbidity postnatally.

Hypoplastic Left Heart Syndrome: Is There a Role for Fetal Therapy?

During fetal life some cardiac defects may lead to diminished left heart growth and to the evolution of a form of hypoplastic left heart syndrome (HLHS). In fetuses with an established HLHS, severe restriction or premature closure of the atrial septum leads to left atrial hypertension and remodeling of the pulmonary vasculature, severely worsening an already poor prognosis. Fetal therapy, including invasive fetal cardiac interventions and non-invasive maternal hyperoxygenation, have been introduced to prevent a possible progression of left heart hypoplasia, improve postnatal outcome, or secure fetal survival. The aim of this review is to cover patient selection and possible hemodynamic effects of fetal cardiac procedures and maternal hyperoxygenation in fetuses with an evolving or established hypoplastic left heart syndrome.

Fetal Hemodynamic Response to Maternal Oxygenation in Normal and Complicated Pregnancies

Maternal oxygenation (MO) is widely applied in obstetrics. Scholars have conducted numerous studies on maternal hyperoxygenation and have reported many theoretical and applied achievements and a number of different points of view. The main purpose of this article is to discuss the effect of maternal oxygenation on fetal circulation during normal and complicated pregnancies and to ascertain its potential side effects and research gaps in this field. In complicated pregnancies, the fetus may benefit from oxygen therapy. However, large randomized controlled trials and longitudinal studies are necessary to support the widespread application of maternal oxygenation in this context.

Maternal hyperoxygenation in congenital heart disease

The importance of prenatal diagnosis and fetal intervention has been increasing as a preventative strategy for improving the morbidity and mortality in congenital heart disease (CHD). The advancements in medical imaging technology have greatly enhanced our understanding of disease progression, assessment, and impact in those with CHD. In particular, there has been a growing focus on improving the morbidity and mortality of fetuses diagnosed with left-sided lesions. The disruption of fetal hemodynamics resulting from poor structural developmental of the left outflow tract during cardiogenesis is considered a major factor in the progressive lethal underdevelopment of the left ventricle (LV). This positive feedback cycle of inadequate flow and underdevelopment of the LV leads to a disrupted fetal circulation, which has been described to impact fetal brain growth where systemic outflow is poor and, in some cases, the fetal lungs in the setting of a restrictive interatrial communication. For the past decade, maternal hyperoxygenation (MH) has been investigated as a diagnostic tool to assess the pulmonary vasculature and a therapeutic agent to improve the development of the heart and brain in fetuses with CHD with a focus on left-sided cardiac defects. This review discusses the findings of these studies as well as the utility of acute and chronic administration of MH in CHD.

Cardiac Measurements of Size and Shape in Fetuses With Absent or Reversed End-Diastolic Velocity of the Umbilical Artery and Perinatal Survival and Severe Growth Restriction Before 34 Weeks' Gestation

OBJECTIVES

The purpose of this study was to evaluate the end-diastolic size and shape of the 4-chamber view as well as the right ventricle (RV) and left ventricle (LV) in growth-restricted fetuses before 34 weeks' gestation with absent or reversed end-diastolic velocity of the umbilical artery and compare the results between those with perinatal deaths and those who survived the neonatal period.

METHODS

Forty-nine fetuses with growth restriction and absent or reversed end-diastolic velocity of the umbilical artery were studied. The size, shape, and sphericity index of the 4-chamber view, RV, and LV were assessed. The number and percentage of fetuses with z score values of less than -1.65 and greater than 1.65 were computed.

RESULTS

Of the 49 fetuses, there were 13 perinatal deaths (27%) and 36 (63%) neonatal survivors. Measurements that were unique for neonatal survivors were an increased RV apical transverse width and decreased measurements of the following: LV and RV widths, LV and RV areas, as well as RV sphericity indices.

CONCLUSIONS

Fetuses with a smaller RV and LV size and area and those with a globular-shaped RV were at significantly lower risk for perinatal death.

Analysis of 3-Dimensional Arch Anatomy, Vascular Flow, and Postnatal Outcome in Cases of Suspected Coarctation of the Aorta Using Fetal Cardiac Magnetic Resonance Imaging

BACKGROUND

Identifying fetuses at risk of severe neonatal coarctation of the aorta (CoA) can be lifesaving but is notoriously challenging in clinical practice with a high rate of false positives. Novel fetal 3-dimensional and phase-contrast magnetic resonance imaging (MRI) offers an unprecedented means of assessing the human fetal cardiovascular system before birth. We performed detailed MRI assessment of fetal vascular morphology and flows in a cohort of fetuses with suspected CoA, correlated with the need for postnatal intervention.

METHODS

Women carrying a fetus with suspected CoA on echocardiography were referred for MRI assessment between 26 and 36 weeks of gestation, including high-resolution motion-corrected 3-dimensional volumes of the fetal heart and phase-contrast flow sequences gated with metric optimized gating. The relationship between aortic geometry and vascular flows was then analyzed and compared with postnatal outcome.

RESULTS

Seventy-two patients (51 with suspected fetal CoA and 21 healthy controls) underwent fetal MRI with motion-corrected 3-dimensional vascular reconstructions. Vascular flow measurements from phase-contrast sequences were available in 53 patients. In the CoA group, 25 of 51 (49%) required surgical repair of coarctation after birth; the remaining 26 of 51 (51%) were discharged without neonatal intervention. Reduced blood flow in the fetal ascending aorta and at the aortic isthmus was associated with increasing angulation (P=0.005) and proximal displacement (P=0.006) of the isthmus and was seen in both true positive and false positive cases. A multivariate logistic regression model including aortic flow and isthmal displacement explained 78% of the variation in outcome and correctly predicted the need for intervention in 93% of cases.

CONCLUSIONS

Reduced blood flow though the left heart is associated with important configurational changes at the aortic isthmus in fetal life, predisposing to CoA when the arterial duct closes after birth. Novel fetal MRI techniques may have a role in both understanding and accurately predicting severe neonatal CoA.

Foramen Ovale Restriction in a Late Gestation Fetus Resembling Hypoplastic Left Heart Syndrome

A pregnant woman presented at term with a fetus with foramen ovale restriction. We illustrate the contrast between fetal and postnatal echocardiography of this rare entity. (Level of Difficulty: Advanced.)

Early Chronic Intermittent Maternal Hyperoxygenation Impairs Cortical Development by Inhibition of Pax6-Positive Apical Progenitor Cell Proliferation

Maternal hyperoxygenation is a feasible, noninvasive method to treat fetal diseases, such as heart hypoplasia, but effects of maternal hyperoxygenation on the developing brain remain poorly understood. Previous studies showed that short-term maternal hyperoxygenation during midneurogenic phase (E14-E16) but not in earlier development (E10-E12) increases oxygen tension and enhances neurogenesis in the developing mouse cortex. We investigated effects of early chronic maternal hyperoxygenation (CMH) as a potential clinical treatment. Pregnant C57BL/6J mice were housed in a chamber at 75% atmospheric oxygen and the brains of E16 fetuses were analyzed using immunohistochemistry. The mitosis marker phH3 showed a significant reduction of proliferation in the dorsolateral cortices of CMH-treated E16 fetuses. Numbers of Tbr2-positive intermediate progenitor cells were unaffected whereas numbers of Pax6-positive apical progenitor cells were significantly reduced in CMH-treated mice. This resulted in altered cortical plate development with fewer Satb2-positive upper layer neurons but more Tbr1-positive neurons corresponding to the deeper layer 6. Thus, maternal hyperoxygenation affects the developing cortex depending on timing and length of applied oxygen. Early CMH causes a severe reduction of neuroprogenitor proliferation likely affecting cortical development. Further studies are needed to investigate the mechanisms underlying these findings and to assess the clinical and neurodevelopmental outcomes of the pups.

Calling into question the future of hyperoxygenation in pregnancy

Maternal hyperoxygenation has been investigated as a potential diagnostic and therapeutic tool since the 1960s. Since then, it has been applied in many obstetric scenarios, both clinically and in the research setting. It is often administered without any determination of pre-hyperoxygenation maternal or fetal oxygen levels. Studies focussing on maternal oxygen therapy for the treatment of fetal growth restriction have been ongoing for over thirty years and there remains no clear evidence of benefit. Studies investigating the potential diagnostic or therapeutic role of maternal oxygen therapy in the setting of fetal congenital cardiac disease have reported varying success rates and some potentially worrying adverse effects. The purpose of this article is to review the effects of maternal hyperoxygenation on fetal and maternal health and to ascertain the safety of undertaking further clinical trials that employ the use of hyperoxygenation in pregnancy.

Redundancy of foramen ovale flap may mimic fetal aortic coarctation

OBJECTIVES

To assess the relationship between presence of a redundant foramen ovale flap (RFOF), in the absence of a clearly restrictive foramen ovale, and ventricular disproportion, in three groups of fetuses: (1) those with a final diagnosis of aortic coarctation (CoA); (2) those referred for suspicion of ventricular disproportion and/or CoA which did not develop CoA postnatally; and (3) normal fetuses.

METHODS

This was a retrospective study including 73 fetuses: 12 with a final diagnosis of isolated CoA; 30 referred for suspicion of ventricular disproportion and/or CoA, which did not develop CoA postnatally; and 31 normal fetuses. Four-dimensional volume datasets and clips were assessed offline. Maximum diameters of the FOF (FOFD), left atrium (LAD), right atrium, left and right ventricles and, when available, aortic isthmus, were measured, as were areas of the FOF (FOFA), left atrium (LAA) and right atrium. The left/right ratios for all segments of the heart, as well as the FOFD/LAD ratio and FOFA/LAA ratio, were calculated. Regression analysis was performed to assess the relationship between RFOF and ventricular disproportion and means were compared by ANOVA.

RESULTS

Repeatability was fair, with all variables having an intraclass correlation coefficient ≥ 83%. In the pooled group of fetuses with no CoA found at birth (normal fetuses plus those with ventricular disproportion (n = 61)), there was a significant linear correlation between redundancy of the FOF and degree of ventricular disproportion (P < 0.01 and P < 0.05 for diameter and area ratios, respectively). Categorizing the FOF redundancy, FOFD/LAD ratio ≥ 0.65 was significantly associated with ventricular disproportion (P = 0.006). Based on the degree of FOF prominence, we described four categories of redundancy, ranging from no redundancy/ventricular disproportion (Stage 0) to severe redundancy/ventricular disproportion with transient obstruction of the foramen ovale or mitral orifice (Stage III). Comparing cases without neonatal evidence of coarctation but FOFD/LAD ratio ≥ 0.65 vs those with neonatal evidence of coarctation, there was no statistically significant difference in the degree of ventricular disproportion or in the Z-score of the aortic isthmus maximum diameter.

CONCLUSIONS

This study demonstrates that: (1) there is an association between RFOF and ventricular disproportion, independent of the association with a restrictive foramen ovale, and (2) the presence of a RFOF may mimic CoA. In fact, it causes both ventricular disproportion and a significant reduction in the diameter of the aortic isthmus, associated in some cases also with reversed isthmic flow. Future prospective studies are needed to evaluate whether focusing the sonologist's attention on the appearance of the foramen ovale may reduce the rate of false-positive diagnosis of CoA. Copyright © 2020 ISUOG. Published by John Wiley & Sons Ltd.

Ebstein's anomaly: epidemiological analysis and presentation of different prenatal management

OBJECTIVES

To present the crucial role of echocardiographic examination in perinatal care and analyze influence of prenatal treatment for neonatal outcome. Furthermore, the attempt to answer the question if there was any relationship between the occurrence of fetal Ebstein's anomaly and environmental risk factors in polish population.

METHODS

Forty-five prenatal diagnoses of Ebstein's anomaly were compiled over the 21-year period (1998‒2018) form our single unit. The analysis included the assessment of maternal parameters (age, past obstetric history, and place of residence) and fetal parameters (sex, gestational age, anatomy, the fetal cardiovascular condition assessed by the CVPS, associated extracardiac anomalies or malformations, prenatal treatment, delivery and follow-up).

RESULTS

The average age of gravida was 29.5 years (± 5.2 years) and gravidae <35 years of age accounted for 80% . There were 43 singleton pregnancies and 2 cases of multiple pregnancy. Ebstein's anomaly was mostly (averagely) diagnosed at 28th week of gestation. Forty-three fetuses had normal karyotypes and two had trisomy 21. Cardiomegaly was present in 91% (41) of fetuses. The average heart area to chest area ratio was 0.56 (± 0.12). In 21 cases, there was only fetal monitoring - echocardiographic examinations and postnatal mortality was 44.4%. In 5 cases, transplacental digoxin treatment was administered and mortality was: 40%. In another 5 cases, only steroid therapy was applied and postnatal mortality was 100%. Steroids and transplacental digoxin treatment were administered in 11 cases and mortality was 63.6%. In 3 last cases transplacental digoxin treatment, steroids and maternal hyperoxygenation therapy were given and mortality was 0%. Cesarean section rate was 49%. Moreover, due to Ebstein's anomaly regional peak of occurrence benzopyrene was deliberated as environmental risk factor.

CONCLUSIONS

Fetal Ebstein's anomaly occurred in our population in healthy young women, expecting their first child and malformation was not related to fetus gender, nor to maternal health condition. Our data can be a new signal for the development of novel treatment strategies in therapy in fetuses with Ebstein's anomaly.

Cerebral hemodynamic response to short-term maternal hyperoxygenation in fetuses with borderline small left hearts

BACKGROUND

Hypoxia delays brain maturation and contributes to neurodevelopmental morbidity in fetuses with congenital heart defects (CHDs). Maternal hyperoxygenation (MH) can, in theory, promote oxygen/nutrient delivery to the fetal brain, owing to an improved heart structure/function and increased fetal oxygen content. We aimed to determine whether MH alters fetal cerebral hemodynamics in fetuses with CHD.

METHODS

Twenty-eight fetuses with borderline small left hearts and 28 age-matched normal fetuses were enrolled and subdivided by gestational age (GA): 23^+ 0 ~ 27^+ 6 weeks and 28^+ 0 ~ 36^+ 6 weeks. The middle cerebral artery pulsatility index (MCA-PI), vascular index (VI), flow index (FI) and vascular/flow index (VFI) were measured with baseline room air, after 10 min of MH and after 10 min of recovery for all subjects.

RESULTS

MCA-PI, VI, FI and VFI did not differ with MH in the normal fetuses. In fetuses with borderline small left hearts, MCA-PI increased and VI, FI and VFI significantly decreased during the 3rd trimester (from 1.44 ± 0.27, 3.19 ± 0.87, 56.91 ± 9.19, and 1.30 ± 0.33 at baseline to 1.62 ± 0.15, 2.37 ± 0.37, 45.73 ± 4.59, and 0.94 ± 0.15 during MH, respectively, P < 0.05), but this response was not apparent during mid-gestation (p > 0.05). These parameters returned to the baseline levels during the recovery phase. The change in cerebral perfusion depended on the baseline MCA-PI and increased the combined cardiac index (CCOi).

CONCLUSIONS

MH alters the cerebral hemodynamics of fetuses with borderline small left hearts during the third trimester. Further investigation is needed to determine whether MH may benefit brain growth and neurodevelopment in this high-risk population.

Advances in fetal echocardiography: myocardial deformation analysis, cardiac MRI and three-dimensional printing

PURPOSE OF REVIEW

Advances in ultrasound technology have led to new ways of evaluating cardiac function and structure, including myocardial deformation imaging (strain and strain rate), cardiac MRI and three-dimensional (3D) printing. As ultrasound technology has improved, it has become possible to use these modalities to evaluate the fetal heart. This article will review some of the more recent developments in applying these techniques to the evaluation of fetal cardiac structure and function.

RECENT FINDINGS

Myocardial deformation analyses have led to the establishment of normative values for strain and strain rate in the fetal heart and have also been used to evaluate fetal heart function in both fetal disease states and maternal disease states. Technological advances in MRI technology, 3D imaging and 3D printing have opened up new methods of evaluating fetal structural heart disease.

SUMMARY

A deeper understanding of the subtleties of myocardial dysfunction in various fetal and maternal disease states may elucidate the pathophysiology involved and lead to new treatment and/or counseling paradigms that may ultimately affect outcome. Similarly, the ability to image the fetal heart in new ways, including fetal MRI and 3D printing, could potentially change fetal counseling techniques and prenatal planning.

Current and future role of fetal cardiovascular MRI in the setting of fetal cardiac interventions

Over recent years, technical developments resulting in the feasibility of fetal cardiovascular magnetic resonance (CMR) have provided a new diagnostic tool for studying the human fetal heart and circulation. During the same period, we have witnessed the arrival of several minimally invasive fetal cardiac interventions (FCI) as a possible form of treatment in selected congenital heart diseases (CHDs). The role of fetal CMR in the planning and monitoring of FCI is not yet clear. Indeed, high-quality fetal CMR is not available or routinely offered at most centers caring for patients with prenatally detected CHD. However, in theory, fetal CMR could have much to offer in the setting of FCI by providing complementary anatomic and physiologic information relating to the specific intervention under consideration. Similarly, fetal CMR may be useful as an alternative imaging modality when ultrasound is hampered by technical limitations, for example, in the setting of oligohydramnios and in late gestation. In this review, we summarize current experience of the use of fetal CMR in the diagnosis and monitoring of fetuses with cardiopathies in the setting of a range of invasive in utero cardiac and vascular interventions and medical treatments and speculate about future directions for this versatile imaging medium.

Hemodynamic factors associated with fetal cardiac remodeling in late fetal growth restriction: a prospective study

Background Altered cardiac geometry affects a proportion of fetuses with growth restriction (FGR). The aim of this study was to explore the hemodynamic factors associated with cardiac remodeling in late FGR. Methods This was a prospective study of singleton pregnancies complicated by late-onset FGR undergoing assessment of left (LV) and right (RV) ventricular sphericity-index (SI). The study population was divided in two groups according to the presence of cardiac remodelling, defined as LVSI <5th centile. The following outcomes were explored: gestational age at birth, birthweight, caesarean section (CS) for fetal distress, umbilical artery (UA) pH and neonatal admission to special care unit. The differences between the 2 groups in UA pulsatility index (PI), middle cerebral artery (MCA) PI, uterine artery PI, cerebroplacental ratio (CPR) and umbilical vein (UV) flow corrected for fetal abdominal circumference (UVBF/AC) were tested. Results In total, 212 pregnancies with late FGR were enrolled in the study. An abnormal LV SI was detected in 119 fetuses (56.1%). Late FGR fetuses with cardiac remodeling had a lower birthweight (2390 g vs. 2490; P = 0.04) and umbilical artery pH (7.21 vs. 7.24; P = 0.04) and were more likely to have emergency CS (42.8% vs. 26.9%; P = 0.023) and admission to special care unit (13.4% vs. 4.3%; P = 0.03) compared to those with normal LVSI. No difference in either UA PI (p = 0.904), MCA PI (P = 0.575), CPR (P = 0.607) and mean uterine artery PI (P = 0.756) were present between fetuses with or without an abnormal LV SI. Conversely, UVBF/AC z-score was lower (-1.84 vs. -0.99; P ≤ 0.001) in fetuses with cardiac remodeling and correlated with LV (P ≤ 0.01) and RV SI (P ≤ 0.02). Conclusion Fetal cardiac remodelling occurs in a significant proportion of pregnancies complicated by late FGR and is affected by a high burden of short-term perinatal compromise. The occurrence of LV SI is independent from fetal arterial Dopplers while it is positively associated with umbilical vein blood flow.

New Aspects in the Diagnosis and Therapy of Fetal Hypoplastic Left Heart Syndrome

Fetal hypoplastic left heart syndrome (HLHS) is a severe congenital heart disease with a lethal prognosis without postnatal therapeutic intervention or surgery. The aim of this article is to give a brief overview of new findings in the field of prenatal diagnosis and the therapy of HLHS. As cardiac output in HLHS children depends on the right ventricle (RV), prenatal assessment of fetal RV function is of interest to predict poor functional RV status before the RV becomes the systemic ventricle. Prenatal cardiac interventions such as fetal aortic valvuloplasty and non-invasive procedures such as maternal hyperoxygenation seem to be promising treatment options but will need to be evaluated with regard to long-term outcomes. Novel approaches such as stem cell therapy or neuroprotection provide important clues about the complexity of the disease. New aspects in diagnostics and therapy of HLHS show the potential of a targeted prenatal treatment planning. This could be used to optimize parental counseling as well as pre- and postnatal management of affected children.

Hyperoxygenation in pregnancy exerts a more profound effect on cardiovascular hemodynamics than is observed in the nonpregnant state

BACKGROUND

Supplemental oxygen is administered to pregnant women in many different clinical scenarios in obstetric practice. Despite the accepted uses for maternal hyperoxygenation, the impact of hyperoxia on maternal hemodynamic indices has not been evaluated. As a result, there is a paucity of data in the literature in relation to the physiological changes to the maternal circulation in response to supplemental oxygen.

OBJECTIVE

The hemodynamic effects of oxygen therapy are under-recognized and the impact of hyperoxygenation on maternal hemodynamics is currently unknown. Using noninvasive cardiac output monitoring which employs transthoracic bioreactance, we examined the effect of brief hyperoxygenation on cardiac index, systemic vascular resistance, blood pressure, stroke volume, and heart rate in pregnant mothers during the third trimester, compared with those effects observed in a nonpregnant population subjected to the same period of hyperoxygenation.

STUDY DESIGN

Hemodynamic monitoring was performed in a continuous manner over a 30-minute period using noninvasive cardiac output monitoring. Hyperoxygenation (O₂ 100% v/v inhalational gas) was carried out at a rate of 12 L/min via a partial non-rebreather mask for 10-minutes. Cardiac index, systemic vascular resistance, stroke volume, heart rate, and blood pressure were recorded before hyperoxygenation, at completion of hyperoxygenation, and 10 minutes after the cessation of hyperoxygenation. Two-way analysis of variance with repeated measures was used to assess the change in hemodynamic indices over time and the differences between the 2 groups.

RESULTS

Forty-six pregnant and 20 nonpregnant women with a median age of 33 years (interquartile range, 26-38 years) and 32 years (interquartile range, 28-37 years) were recruited prospectively, respectively (P=.82). The median gestational age was 35 weeks (33-37 weeks). In the pregnant group, there was a fall in cardiac index during the hyperoxygenation exposure period (P=.009) coupled with a rise in systemic vascular resistance with no recovery at 10 minutes after cessation of hyperoxygenation (P=.02). Heart rate decreased after hyperoxygenation exposure and returned to baseline by 10 minutes after cessation of therapy. There was a decrease in stroke volume over the exposure period, with no change in systolic or diastolic blood pressure. In the nonpregnant group, there was no significant change in the cardiac index, systemic vascular resistance, stroke volume, heart rate, or systolic or diastolic blood pressure during the course of exposure to hyperoxygenation.

CONCLUSION

Hyperoxygenation during the third trimester is associated with a fall in maternal cardiac index and a rise in systemic vascular resistance without recovery to baseline levels at 10 minutes after cessation of hyperoxygenation. The hemodynamic changes that were observed in this study in response to hyperoxygenation therapy during pregnancy could counteract any intended increase in oxygen delivery. The observed maternal effects of hyperoxygenation call for a reevaluation of the role of hyperoxygenation treatment in the nonhypoxemic pregnant patient.

Right and left ventricular 24-segment sphericity index is abnormal in small-for-gestational-age fetuses

OBJECTIVE

Fetuses with growth restriction have been reported to have an abnormal sphericity index (SI), which is indicative of the shape of the ventricular chambers of the heart. Our aim was to evaluate the SI for 24 transverse segments distributed from base to apex of the right (RV) and left (LV) ventricles to determine whether, in small-for-gestational-age (SGA) fetuses, the SI is abnormal at locations other than the basal segment.

METHODS

We evaluated 30 SGA fetuses between 25 and 37 weeks of gestation. SI was computed for both ventricles by dividing the end-diastolic mid-basal-apical length by each of 24 end-diastolic transverse segmental widths, from base (Segment 1) to apex (Segment 24). For each ventricle, the Z-score and centile for the SI from each of the 24 segments were computed using the mean and SD from published equations. The 24-segment method, defining abnormal SI as values < 10^th centile or > 90^th centile, was compared with that of using only the basal segment by chi-square analysis to determine the number of fetuses identified with an abnormal SI.

RESULTS

In 23 of the 30 (77%) SGA fetuses, at least one of the 24 transverse segments in one or both ventricles had an abnormal SI; in 17% of cases, both ventricles were affected, in 23% of cases only the RV was involved and in 37% of cases only the LV was involved. Compared with the 24-segment model, significantly fewer fetuses with an abnormal SI were identified using only basal Segment 1, from the RV base (58%, 7/12; P < 0.01) or only Segment 12, in the mid portion of the RV (50%, 6/12; P < 0.005). Combining measurements of Segment 1 and Segment 12 from the RV identified 83% of fetuses with at least one abnormal SI and was not significantly different from using the 24-segment model. Similarly, significantly fewer fetuses with an abnormal SI were identified using only LV basal Segment 1 (63%, 10/16; P < 0.006) or only Segment 12, in the mid portion of the LV (75%, 12/16; P < 0.03), when compared with the 24-segment model. Combining measurements of both LV Segment 1 and Segment 12 identified 81% (13/16) of fetuses with an abnormal SI and was not significantly different from using the 24-segment model.

CONCLUSION

The 24-segment SI of RV and LV provides a comprehensive method with which to examine the shape of the ventricular chambers and identifies more SGA fetuses with an abnormal SI than are identified using only the basal segment SI. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

24-segment sphericity index: a new technique to evaluate fetal cardiac diastolic shape

OBJECTIVE

Because of parallel circulation in the fetus and the differential effect that various disease states may have on the shape of the right and left ventricles, this study was conducted to evaluate the sphericity index (SI) of 24 transverse segments distributed from the base to the apex of each of the ventricular chambers.

METHODS

Two hundred control fetuses were examined between 20 and 40 weeks of gestation. The displacement of the ventricular endocardium during the cardiac cycle was computed using offline speckle-tracking software. From the ASCII output of the analysis, we analyzed 24 end-diastolic transverse segments, distributed from the base to the apex of each ventricle, as well as the end-diastolic mid-basal-apical length. The SI was computed for each of the 24 segments by dividing the mid-basal-apical length by the transverse length for each segment. Regression analysis was performed against biometric measurements and gestational age according to last menstrual period and ultrasound. Eight fetuses, in which the four-chamber view appeared subjectively to demonstrate chamber disproportion, were evaluated as examples to demonstrate the utility of this technology.

RESULTS

The SI for each segment was independent of gestational age and fetal biometric measurements. The SI of the right ventricle was significantly (P < 0.001) lower than that of the left ventricle for segments 1-18, suggesting that the right ventricle was more globular in shape than was the left ventricle at the base, mid and a portion of the apical segments of the chamber. Fetuses with various cardiac structural abnormalities and abnormal fetal growth had abnormal SI values that reflected either a more globular or a more flattened ventricular chamber.

CONCLUSION

Determination of SI for each of 24 segments of the fetal right and left ventricles provides a comprehensive method to examine the shape of the ventricular chambers. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Recommendations for Prenatal Echocardiography: A Report from International Prenatal Cardiology Collaboration Group

International Prenatal Cardiology Collaboration Group (IPCCG) links specialists from prenatal cardiology all over the world. In this recommendation we would like to focus on the fetal/prenatal echocardiography official report. So far many recommendations focused mainly on technical aspects of the fetal heart examination.

Common Findings in Late-Gestation Fetal Echocardiography

OBJECTIVES

Fetal echocardiography provides detailed information about cardiac structure and function in utero. Limited information is available regarding normal findings late in pregnancy. We therefore sought to identify and describe common cardiac findings in late gestation.

METHODS

Fetuses with structurally normal hearts were identified in mid gestation within a subset of pregnant women in a prospective study. The atrioventricular valves, right and left atria, aortic isthmus and ductus arteriosus dimensions and flow abnormalities, aneurysm of the septum primum, and presence and grade of tricuspid regurgitation were assessed throughout pregnancy. Linear and logistic regression analyses were used to characterize changes in quantitative and qualitative fetal echocardiographic parameters by gestational age (GA).

RESULTS

Forty fetuses between 24 and 38 weeks' GA were studied. Each had a fetal echocardiographic study completed before and after 34 weeks' gestation, which were compared. Tricuspid-to-mitral valve and right-to-left atrium ratios increased with GA (P < .001). More frequently noted after 34 weeks were tapering of the ductus arteriosus (2.5% versus 32%), prominent aortic isthmus diastolic flow (5% versus 67%), prominent ductus arteriosus diastolic flow (2.5% versus 25%), trivial or mild tricuspid regurgitation (35% versus 80%), and aneurysms of the septum primum (37.5% versus 80%). These findings all increased linearly with GA (P < .001).

CONCLUSIONS

Atrioventricular valve and right/left atrium disproportion, mild ductus arteriosus tapering, prominent aortic isthmus and ductus arteriosus diastolic flow, trivial or mild tricuspid regurgitation, and aneurysms of the septum primum are frequently identified after 34 weeks' GA. Their identification suggests that these fetal echocardiographic findings in isolation are likely normal and are results of the physiologic alterations that occur late in the third trimester.

Abnormal Fetal Findings Associated With a Global Sphericity Index of the 4-Chamber View Below the 5th Centile

OBJECTIVES

The purpose of this study was to evaluate the global sphericity index (GSI) of the 4-chamber view and correlate the results with abnormal ultrasound findings.

METHODS

The epicardial end-diastolic basal-apical length (BAL) and transverse length (TL) of the 4-chamber view were measured to compute the GSI (BAL/TL) in 200 control fetuses between 20 and 40 weeks' gestation. Three hundred study fetuses were prospectively examined between 17 and 39 weeks' gestation. The GSI, Z score, and centile were computed for each of the fetuses.

RESULTS

The GSI (1.233; SD, 0.0953) in the control fetuses was independent of gestational age. Eighteen percent of the study fetuses (55 of 300) had a GSI below the 5th centile (<1.08), of whom 96% (53 of 55) had additional abnormal ultrasound findings. Fetuses with an estimated fetal weight below the 10th centile had a significantly (P < .05) higher rate of an umbilical artery Doppler pulsatility index above the 95th centile (27% versus 17.7%), a middle cerebral artery Doppler pulsatility index below the 5th centile (27% versus 0%), an abnormal cerebroplacental ratio (27% versus 4.5%), and an amniotic fluid index of less than 5 cm (36% versus 9%). The TL was significantly increased compared with the BAL in fetuses with cardiac dysfunction, irrespective of the estimated fetal weight.

CONCLUSIONS

An abnormal GSI below the 5th centile is associated with abnormal fetal ultrasound findings.

Sustained maternal hyperoxygenation improves aortic arch dimensions in fetuses with coarctation

The aim was to investigate the impact of maternal hyperoxygenation (HO) on cardiac dimensions in fetuses with isolated Coarctation (CoA). Fetal echocardiography was performed serially in 48 fetuses with CoA and gestation age matched normal fetues. The Z-scores for the mitral valve (MV), tricuspid valve (TV), aortic valve (AV), ascending aorta (AAo), isthmus, pulmonary valve (PV), main pulmonary artery (MPA), and descending aorta (DAo) were measured and compared among normal fetuses, CoA fetuses with oxygen and CoA fetuses with air. In the group with oxygen, 6 L/min oxygen was administered to the mother using a face mask. Regression analyses were performed to identify potential factors for HO outcome. The left heart dimension Z-scores increased gradually during HO therapy periods, especially at 4 weeks after oxygen therapy (P < 0.05). As for the case group with air, the left heart dimension remained unchanged. The duration of HO was associated with aortic arch Z-scores (adjusted R² = 0.199, 0.60 for AAO and isthmus, respectively). Sustained maternal middle-flow oxygenation can be safely used to improve left heart dimensions in fetuses with isolated CoA. The duration of HO were associated with treatment outcome. These findings may provide useful information for developing novel treatment strategies.

Pilot study of chronic maternal hyperoxygenation and effect on aortic and mitral valve annular dimensions in fetuses with left heart hypoplasia

OBJECTIVE

Acute maternal hyperoxygenation (AMH) results in increased fetal left heart blood flow. Our aim was to perform a pilot study to determine the safety, feasibility and direction and magnitude of effect of chronic maternal hyperoxygenation (CMH) on mitral and aortic valve annular dimensions in fetuses with left heart hypoplasia (LHH) after CMH.

METHODS

Gravidae with fetal LHH were eligible for inclusion in a prospective evaluation of CMH. LHH was defined as: sum of aortic and mitral valve annuli Z-scores < -4.5, arch flow reversal and left-to-right or bidirectional atrial level shunting without hypoplastic left heart syndrome or severe aortic stenosis. Gravidae with an affected fetus and with ≥ 10% increase in aortic/combined cardiac output flow after 10 min of AMH at 8 L/min 100% fraction of inspired oxygen were offered enrollment. Nine gravidae were enrolled from February 2014 to January 2015. The goal therapy was ≥ 8 h daily CMH from enrollment until delivery. Gravidae who were cared for from July 2012 to October 2014 with fetal LHH and no CMH were identified as historical controls (n = 9). Rates of growth in aortic and mitral annuli over the final trimester were compared between groups using longitudinal regression.

RESULTS

There were no significant maternal or fetal complications in the CMH cohort. Mean gestational age at study initiation was 29.6 ± 3.2 weeks for the intervention group and 28.4 ± 1.8 weeks for controls (P = 0.35). Mean relative increase in aortic/combined cardiac output after AMH was 35.3% (range, 18.1-47.9%). Median number of hours per day on CMH therapy was 9.3 (range, 6.5-14.6) and median duration of CMH was 48 (range, 33-84) days. Mean mitral annular growth was 0.19 ± 0.05 mm/week compared with 0.14 ± 0.05 mm/week in CMH vs controls (mean difference 0.05 ± 0.05 mm/week, P = 0.33). Mean aortic annular growth was 0.14 ± 0.03 mm/week compared with 0.13 ± 0.03 mm/week in CMH vs controls (mean difference 0.01 ± 0.03 mm/week, P = 0.75). More than 9 h CMH daily (n = 6) was associated with better growth of the aortic annulus in intervention fetuses (0.16 ± 0.03 vs 0.08 ± 0.02 mm/week, P = 0.014).

CONCLUSIONS

CMH is both safe and feasible for continued research. In this pilot study, the effect estimates of annular growth, using the studied method of delivery and dose of oxygen, were small. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Fetal cardiology: changing the definition of critical heart disease in the newborn

Infants born with congenital heart disease (CHD) may require emergent treatment in the newborn period. These infants are likely to benefit the most from a prenatal diagnosis, which allows for optimal perinatal planning. Several cardiac centers have created guidelines for the management of these high-risk patients with CHD. This paper will review and compare several prenatal CHD classification systems with a particular focus on the most critical forms of CHD in the fetus and newborn. A contemporary definition of critical CHD is one which requires urgent intervention in the first 24 h of life to prevent death. Such cardiac interventions may be not only life saving for the infant but also decrease subsequent morbidity. Critical CHD cases may require delivery at specialized centers that can provide perinatal, obstetric, cardiology and cardiothoracic surgery care. Fetuses diagnosed in mid-gestation require detailed fetal diagnostics and serial monitoring during the prenatal period, in order to assess for ongoing changes and identify progression to a more severe cardiac status. Critical CHD may progress in utero and there is still much to be learned about how to best predict those who will require urgent neonatal interventions. Despite improved therapeutic capabilities, newborns with critical CHD continue to have significant morbidity and mortality due to compromise that begins in the delivery room. Fetal echocardiography is the best way to predict the need for specialized care at birth to improve outcome. Once the diagnosis is made of critical CHD, delivery at the proper time and in appropriate institution with specific care protocols should be initiated. More work needs to be done to better delineate the risk factors for progression of critical CHD and to determine which newborns will require specialized care. The most frequently described forms of critical CHD requiring immediate intervention include hypoplastic left heart syndrome with intact or severely restricted atrial septum, obstructed total anomalous pulmonary venous return and transposition of the great arteries with restrictive atrial septum.