Care of the Fetus With Congenital Cardiovascular Disease: From Diagnosis to Delivery Free

The incidence of congenital heart disease (CHD) is estimated at 6 to 12 per 1000 live births and is significantly higher in the prenatal population.^1,–5 The most common referral reason for a fetal echocardiogram that yields a diagnosis of CHD is concern for a structural abnormality on obstetrical (OB) ultrasound.⁶ Fetal echocardiograms yield a diagnosis of CHD in 40% to 50% of referred fetuses.⁷ Other indications for referral include fetal and maternal factors yielding a 2% to 10% increase in risk of CHD (Table 1).⁷ 

Despite advances in ultrasound technology, barriers to CHD detection exist. Historically, OB screening for CHD has a low yield of 10% to 26%,^8,–10 compared with greater than 90% detection by fetal echocardiography in experienced hands.^11,12 Recently, OB ultrasound screening protocols have incorporated multiple views and long clips or “sweeps” of the heart to include not only the 4 chamber view, which detects only ∼50% of major cardiac malformations, but also the outflow tracts and the 3 vessel trachea view, potentially increasing detection up to 90%.^13,–15 Importantly, only 10% of fetuses with CHD present with an identifiable “risk factor,”¹¹ and detection of CHD most often occurs during routine OB ultrasound in low risk patients. For this reason, the OB cardiac screening protocol including the 5 axial views, sweeping from 4 chamber cephalad to the 3-vessel trachea view (Figs 1–3) is recommended. Referral for fetal echocardiogram in the absence of 1 of the aforementioned indications should occur when normal cardiac structures, including the 4 chambers, outflow tracts, and 3 vessel trachea view, cannot be confirmed.^16,17 

Studies supporting survival benefit for neonates prenatally diagnosed with severe or critical CHD are varied.^18,–20 Some of these studies are limited by methodology and do not account for neonates who died at home or in the local hospital.²¹ Many studies, however, have documented improved preoperative and postoperative survival in prenatally diagnosed neonates with dextro-transposition of the great arteries (d-TGA), hypoplastic left heart syndrome (HLHS),^22,23 and many lesions requiring biventricular repair.^20,24,–36 These studies suggest that prenatal diagnosis of CHD allows planning for specialized care at the time of delivery, including timing, location and available services to care for the newborn with CHD.^20,37,–39 Neonates with a prenatal diagnosis of ductal dependent CHD have improved arterial pH and oxygenation, less myocardial dysfunction and end-organ disease, and undergo surgical intervention earlier than neonates diagnosed postnatally.^{24,–27,29,34,40,41} Neonates with a prenatal diagnosis of HLHS have earlier initiation of prostaglandin, less hemodynamic compromise, and fewer neurologic sequelae.^29,41 Finally, prenatal diagnosis allows planning of urgent stabilizing postnatal interventions, such as balloon atrial septostomy (BAS) for d-TGA,^22,42 atrial septoplasty for HLHS with restrictive or intact atrial septum,^24,43,44 and pacing in complete congenital heart block (CHB).⁴⁵ 

Fetal echocardiography is the primary tool for detailed evaluation of fetal cardiovascular anatomy and physiology. Several organizations have published guidelines for imaging^46,–49 with the most recent being collaborative efforts of multiple societies.^7,16,50 Referral for fetal echocardiogram usually occurs between 18 and 22 weeks of gestation. Early fetal echocardiography performed in the late first trimester^51,52 is generally reserved for fetuses at highest risk for CHD. OB ultrasound to assess for extracardiac abnormalities should always accompany a fetal echocardiogram. In the presence of a cardiac abnormality, genetic testing should be offered and pursued after counseling and obtaining parental consent.

When CHD is identified, serial fetal echocardiograms are recommended given the risk of progression of some lesions (Table 2).^12,53 The necessity, timing, and frequency of serial assessments are guided by the type and severity of the lesion, signs of heart failure and potential for progression or risk of fetal demise, anticipated progression, and available options for prenatal and perinatal management. For most CHD requiring early intervention, at least 1 fetal echocardiogram should be performed in late gestation, before delivery.

A fetal echocardiogram should occur in a step-wise approach, evaluating multiple views and sweeps of the fetal heart to ensure a high degree of accuracy in diagnosis of fetal CHD.¹⁶ 

In brief, all fetal echocardiograms should include essential elements (Table 3).¹⁶ Additional detailed evaluation, including quantitative cardiac function assessment, and Doppler evaluation of vessels, such as the middle cerebral artery, umbilical artery and vein, and branch pulmonary arteries, may facilitate recognition and quantification of subtle pathology and progression of disease.⁷ 

Assessment of cardiac function is important to gauge the likelihood or presence of cardiovascular compromise, which may affect fetal prognosis and the possibility of a difficult postnatal transition. Cardiac function can be assessed by different methodologies, including qualitative assessment, measurement of fractional shortening,^54,55 myocardial performance index, or cardiothoracic area ratio.^56,–59 The cardiovascular profile (CVP) score, a 10 point scale evaluating for signs of hydrops, venous and arterial Doppler abnormalities, increased heart size, and diminished ventricular function can be useful to assess fetal heart failure (Table 4).^59,–62 

There are limitations to fetal echocardiography. Defects such as small ventricular septal defects, secundum atrial septal defects, subtle valve abnormalities, anomalous pulmonary venous connections, coronary artery anomalies, and in some cases coarctation of the aorta may not be detected. In addition, cardiac lesions that progress in-utero (Table 2) and some postnatally acquired forms of CHD may not be detected on midgestational imaging.

Multiple new technologies are emerging to image the heart in more detail; however, most are still under investigation. These new tools may allow for improved fetal assessment, which can facilitate improved pre and postnatal prognostication and delivery room (DR) planning. Available tests include: 3D and 4D echocardiography,⁶³ tissue Doppler imaging,^24,64,–69 and strain imaging.^70,–80 

Fetal telecardiology is an emerging care delivery model in which trained OB ultrasonographers perform fetal echocardiograms that are interpreted by a remote fetal cardiologist. This care delivery model has been shown to be feasible with good diagnostic accuracy and patient satisfaction, empowers local health care providers, and is economically beneficial to families.⁸¹ 

Fetal magnetocardiography is a tool to assess fetal rhythm; currently, however, its availability is limited. Fetal electrocardiography is an emerging technology to assess fetal heart rate, rhythm, electrical waveforms and time intervals, and has the potential to be more widely available. These technologies have the capacity to more precisely diagnose fetal arrhythmias and conductions disorders, uncover unsuspected arrhythmias, and assess effects and toxicity of antiarrhythmic therapy that may guide postnatal therapy.^82,–92 

Home fetal heart rate monitoring is an emerging tool that can be used in certain high-risk populations, such as fetuses exposed to anti-SSA (anti–Sjögren’s-syndrome-related antigen A) antibodies at risk for developing irreversible CHB. Performance of home heart rate monitoring by pregnant women has been shown to be feasible, has a low false positive rate, and is empowering to mothers. Monitoring can detect rapid progression of normal rhythm to CHB and potentially allow for prompt treatment to restore sinus rhythm.^93,94 

Fetal MRI is now being used in the assessment of fetuses with significant CHD. Reports suggest utility in the evaluation of situs,^95,–98 cardiac structure,^{95,96,99,–102} and cardiac function,^102,103 particularly with adverse fetal position, maternal obesity, in late gestation, and in the presence of oligohydramnios.¹⁰⁴ More advanced MRI techniques provide physiologic information, including vessel blood flow, oxygen saturation, and hematocrit, which have been used to investigate physiologic abnormalities in CHD.^104,–106 Fetal MRI has also been useful to assess brain development in fetuses with CHD. There is increasing evidence that CHD is associated with abnormalities in brain structure, altered in-utero brain growth, and brain injury, suggesting there are antenatal factors impacting neurodevelopmental outcome.^{105,107,–115} MRI appears to be safe for fetus and mother although its use is still limited in most centers given need for complex and prolonged post-processing treatment.^116,117 

CHD is associated with other structural and/or genetic anomalies (Tables 5 and 6). Infants with CHD may have extracardiac anomalies in up to 20% of cases¹ and in fetuses, this can be as high as 50% to 70%.^{10,118,–120} Identification of a genetic abnormality can allow for testing of family members, predict recurrence in future pregnancies, modify prognosis, and inform decisions about the pregnancy, including termination or palliative care.^121,122 Prenatal diagnosis of extracardiac abnormalities or genetic conditions has important implications for DR and postnatal care planning and can markedly affect prognosis. Detailed OB ultrasound to assess for extracardiac abnormalities and associated genetic abnormalities once parental consent is obtained, is recommended for all fetuses with CHD.

Approximately 15% of infants with CHD have chromosomal abnormalities,¹²³ the majority of which are trisomies 21, 13, 18 and monosomy.^{118,–120,124,–127} Many types of genetic testing are currently clinically available.¹²⁸ Invasive options include chorionic villus sampling and amniocentesis for karyotyping, fluorescent in-situ hybridization and microarray-based comparative genomic hybridization testing and gene sequencing including whole exome sequencing. Noninvasive prenatal testing is now available using parallel sequencing of cell free DNA to screen for likelihood of a major chromosome abnormality, including trisomy 21, 13, 18 and abnormalities in the sex chromosomes. Specificity is as high as 95% to 99%, however, this is a screening test and definitive diagnosis can only be made with more invasive testing.^129,–133 When noninvasive prenatal genetic testing is used, confirmation of findings is recommended either during pregnancy or after delivery.

1. Screening of the fetal heart during the OB ultrasound should include a cardiac screening exam, which includes views of the 4 chambers, outflows, and 3 vessel trachea view. All fetuses in which a normal heart cannot be confirmed should be referred for fetal echocardiogram (Class I, LOE B-NR)

2. After a prenatal diagnosis of CHD:

   • Detailed prenatal counseling should be performed for families outlining diagnosis, prognosis, short and long term medical and functional outcomes (Class I, LOE C-EO)

3. Assessment for extracardiac abnormalities should be performed (Class I, LOE B-NR)

4. Assessment for genetic abnormalities should be performed once parental consent is obtained (Class I, LOE B-NR)

5. Serial fetal echocardiograms should be performed in specific congenital heart disease to assess for progression of disease or signs of fetal compromise (Class I, LOE B-NR)

6. A final fetal echocardiogram should be performed in specific congenital heart disease in the third trimester to facilitate DR and immediate postnatal planning (Class I, LOE B-NR)

Once a fetal cardiac abnormality is suspected during OB screening, a fetal cardiology consultation should be undertaken. This includes a fetal echocardiogram with a fetal or pediatric cardiologist to confirm the diagnosis and perform a detailed anatomic and hemodynamic assessment, counsel the family, and coordinate in-utero management and a delivery plan.^6,134,135 

Prenatal counseling should provide the family with as accurate as possible diagnosis of the malformation, a clear and truthful picture of the prognosis, outline available in-utero and postnatal management and treatment options, and assist expectant parents in decision making.¹³⁶ Information should be relayed to the family by a medical professional with knowledge concerning the available therapies, operative outcomes, short and long-term survival and neurodevelopmental and other functional outcomes. Counseling should occur in a timely manner after the fetal echocardiogram has been performed, ideally on the same day. This setting allows the practitioners to relay the pertinent information, answer family questions, alleviate potential guilt, stress and anxiety, provide family support resources, assist with decision making and create a plan of care for the fetus and postnatal follow-up.⁷ 

The fetal or pediatric cardiologist should relay complex medical information at an appropriate comprehension level for the family.¹³⁷ Family interpersonal dynamics and the education level impact how effective information is delivered. It should be noted that the information most relevant or desired by the family may be different than the topics the physician believes are most important.¹³⁸ 

News that the fetus has CHD can induce significantly heightened emotions. These may impede the transfer of knowledge from the cardiologist, who must determine the ideal pace for discussion.¹³⁹ It may be necessary to divide or repeat counseling sessions over multiple visits to ensure that the family fully comprehends the diagnosis.

Maternal and paternal mental health and family support play important roles in the outcome for both mother and baby. Almost every aspect of the patient encounter from initial suspicion of CHD,¹⁴⁰ fetal cardiology referral,¹⁴¹ and confirmation of prenatal diagnosis^142,–144 is associated with increased maternal stress when compared with a postnatal diagnosis of CHD. Expectant mothers with a fetal diagnosis of CHD are at increased risk for posttraumatic stress (39%), depression (22%), and anxiety (31%), though healthy partner relationships and positive coping mechanisms can buffer stressors and promote resiliency.¹⁴⁵ Maternal stress does bear negative effects on outcomes^146,–149 and fetal health.^150,151 Elevations in maternal cortisol affect fetal growth, fetal cardiovascular and metabolic function, and infant behavior.^152,–155 For this reason, screening and appropriate treatment of family stress, depression, and anxiety should be essential components of the family assessment.^156,–159 

Families generally desire a clear description of the fetal cardiac diagnosis and implications for short and long term prognosis.¹³⁸ Surveys suggest that families want written information, access to a safe website, support from parents with similar experiences, and continued contact with a specialist liaison.¹⁶⁰ Pictures of a normal heart and the CHD aid in helping families understand the anatomy and interventions that might be needed.¹⁶¹ Attention should be given to details of the diagnosis, including possible progression or a change in diagnosis or prognosis. All treatment options should be discussed, including termination of pregnancy and palliative care.^121,162 Standard treatment as well as available newer techniques and outcomes should be reviewed. Pre and postoperative medical and surgical management strategies should be summarized, including what is planned, timing and recovery from the initial procedure(s), durability of the intervention(s), need for ongoing treatments or additional surgeries, and common associated comorbidities. For fetal arrhythmia diagnoses, the discussion of treatment options may include risks and benefits of transplacental medical therapy and anticipated postnatal monitoring and treatment. Importantly, scientific uncertainties including difficulties of accurately predicting long-term morbidity and challenges in diagnosis and management should be acknowledged.⁷ Unfortunately, many families report receiving no internet resources, information about success rates at other hospitals, or support group information.¹⁷⁷ 

A complete understanding of what to expect for their child, from the fetal period to adulthood, is needed to aid the family in making informed choices for their baby, both in-utero and after delivery.¹³⁸ Short-term medical comorbidities include feeding difficulties occasionally necessitating gastrostomy tube placement. Postoperative feeding often impacts hospital length of stay.^178,179 There is evidence linking neonatal CHD with neurodevelopmental disabilities.^180,–182 Families report receiving inadequate counseling on this risk.¹³⁸ A survey of fetal providers worldwide revealed that although 96% were aware of the link between neurodevelopmental issues and CHD, 18% did not routinely discuss this risk with parents.¹⁸³ 

A diagnosis of severe CHD requires the coordinated care of numerous specialties, including cardiologists, obstetricians, neonatologists, cardiac intensivists, surgeons and case managers or social workers. Tours of the neonatal and cardiac intensive care units, as well as an introduction to the neonatal or cardiac intensivist, interventionalist and/or surgeon may be useful to familiarize the family with the care team.^135,184 For fetuses with complex diagnoses and/or poor prognoses, early involvement of a palliative care team may be helpful.¹⁸⁵ In some institutions, the palliative care teams may also be used to provide psychosocial, spiritual, and/or communication support to help mitigate stress to families of fetuses or neonates diagnosed with congenital heart disease.^186,187 Referral to mental health service providers may also benefit mothers and families.

• Detailed prenatal counseling for families outlining diagnosis, prognosis, short and long term medical comorbidities, and functional outcomes should occur (Class I, LOE C-EO)

• Screening and appropriate treatment of family stress, depression, and anxiety as essential components of the maternal and family assessment should be considered (Class IIa, LOE C-LD)

Fetal therapy is generally reserved for carefully selected, severe cardiovascular abnormalities. Current available therapies include fetal medical treatment, primary invasive catheter-based interventions, chronic maternal hyper-oxygenation therapy, and fetal surgery in rare instances (Table 7). Though the utility of fetal intervention is under investigation and the risk may be high, some families may benefit from referral to a fetal intervention center. A detailed fetal echocardiogram with comprehensive assessment from a specialized fetal intervention care team should be performed before any fetal intervention.

Sustained fetal tachyarrhythmias are associated with increased risk of cardiac failure, fetal morbidity, and perinatal death. Administration of antiarrhythmic medications to the pregnant woman that pass through the placenta to the fetus (transplacental therapy) is recommended for sustained tachyarrhythmias and for some intermittent arrhythmias, particularly if fetal heart failure or hydrops fetalis is present.^188,189 In rare cases where fetal compromise is present and the arrhythmia is unresponsive to transplacental therapy, fetal intramuscular or intravascular injection of an antiarrhythmic has been reported.^190,–192 

Bradycardia resulting from fetal CHB is associated with increased perinatal morbidity and mortality. Although corticosteroids are unlikely to reverse CHB, there is some evidence suggesting a benefit of steroids to inhibit progression from first- or second-degree block to CHB, minimize myocardial injury, or to improve survival if CHB is present.^193,–199 Fetal pacemaker placement has been studied in a sheep model of CHB,^200,–202 but has not yet been attempted in humans as the appropriate candidates, timing, and risk-benefit ratio remain unknown. Beta symathomimetics such as terbutaline have been used to increase fetal heart rate in anti-SSA related CHB²⁰³; however, there are no data supporting improved survival. Digoxin has been used to treat fetal heart failure. One retrospective fetal study demonstrated that fetal cardiovascular status, as assessed by the cardiovascular profile (CVP) score, favorably increased in fetuses with heart failure receiving digoxin.²⁰⁴ 

In-utero fetal aortic valvuloplasty has been used for critical aortic stenosis in the setting of evolving HLHS with the rationale that the procedure may minimize progression of myocardial injury and decreased left ventricular growth, resulting in a univentricular circulation. Fetal aortic valvuloplasty has been shown in single center experiences and in a report of an international experience from the International Fetal Cardiac Intervention Registry to increase the likelihood of a postnatal biventricular repair. Patients with biventricular repair were reported to have a lower number of postnatal interventions and similar neurodevelopmental delays compared with those with univentricular palliation. The risk of fetal demise secondary to in-utero intervention is not negligible and must also be considered.^205,–214 HLHS with restrictive foramen ovale (FO) or intact atrial septum portends an extremely high postnatal morbidity and mortality. Fetal atrial septoplasty using catheter-based intervention with balloon and/or stent or laser have been reported in this high-risk population. A report from the International Fetal Cardiac Intervention Registry documented no significant survival benefit between the fetal intervention and nonintervention groups cesarean section, ex-utero intrapratum treatment (EXIT) delivery, and need for neonatal resuscitation.²¹⁰ A few centers have reported successful fetal pulmonary valvuloplasty in fetuses with critical pulmonary stenosis or atresia with neonatal survivors achieving a biventricular repair.^216,–218 Registry data has confirmed procedural technical success, but cannot yet predict success to biventricular repair.²¹⁰ 

Fetal intervention is an evolving therapeutic option with potential short-term benefit in select CHD, however, long-term outcomes are unknown. Fetal intervention may be considered for select cases, though more research is needed.

The administration of maternal hyperoxygenation in the third trimester increases fetal pulmonary blood flow and left sided heart filling. This strategy has been proposed to “grow” the left heart in cases of a borderline left ventricle or concern for coarctation.^219,–221 A pilot study of chronic maternal hyperoxygenation used for borderline left heart structures demonstrated maternal and fetal safety but minimal effects on left heart growth.²²¹ Studies have demonstrated growth of aortic arch dimensions in fetuses at risk for coarctation.^222,223 However, maternal hyperoxygenation may lead to alterations in the circulation that may adversely affect the fetal circulation, including changes in ductal flow and the pulmonary vascular bed. Chronic maternal hyperoxygenation may also exert negative effects on fetal brain development, with one series demonstrating concerning decreased fetal head growth possibly secondary to alterations in fetal blood flow that may have affected the cerebral circulation.^224,–226 The safety and utility of chronic maternal hyperoxygenation is currently under debate; its use cannot be recommended outside of a research protocol or a clinical trial.^226,227 

• A detailed fetal echocardiogram from a specialized fetal intervention care team should be performed before any fetal intervention (Class I, LOE C-EO)

• Maternal transplacental therapy is recommended for sustained tachyarrhythmias and for some intermittent arrhythmias (Class I, LOE B-NR)

• In a fetus with anti-SSA mediated conduction abnormalities, corticosteroids may inhibit progression of first or second-degree heart block to CHB and may improve survival in the fetus with CHB (Class IIb, LOE B-NR)

• Fetal transcatheter intervention may be considered for carefully selected fetuses with specific severe cardiovascular abnormalities that are known to progress in-utero such as critical aortic stenosis with evolving HLHS or for HLHS with a severely restricted FO or intact atrial septum (Class IIb, LOE C-LD).

• Chronic maternal hyperoxygenation cannot be recommended until further studies are performed (Class III, LOE C-EO)

Before consideration of delivery logistics and postnatal planning in prenatally diagnosed CHD, a comprehensive evaluation of mother and fetus should occur. Information regarding maternal medical, surgical, and OB history, and current pregnancy complications may direct the need for specialized personnel and resources. This information may impact the location, mode, and timing of delivery.²²⁸ In addition, extracardiac findings or a genetic syndrome may drive recommendations for delivery, resulting in either a higher level of neonatal care²²⁹ or consideration of palliative care.¹²² 

For the most comprehensive care, a multidisciplinary team should include obstetrics, maternal fetal medicine specialists, neonatology, fetal or pediatric cardiology, and palliative care, when appropriate. Depending on maternal conditions, the complexity of the fetal cardiac diagnosis and extracardiac findings, consideration for transfer to a comprehensive fetal care center or tertiary cardiac center may be necessary.²³⁰ In all fetal CHD cases, multidisciplinary review, clear and consistent communication and planning, and situational awareness must be integrated into institutional approaches to enhance outcomes for both mother and fetus.

Delivery planning and DR management strategies based on fetal CHD risk stratification of anticipated medical or interventional level of care needed for stabilization using detailed fetal echocardiography findings allow planning to achieve fetal and neonatal stability in the DR.^231,232 In general, fetal echocardiography findings accurately predict the need for specialized immediate DR care and necessary urgent postnatal interventions.^7,233,–235 Determination of an appropriate DR strategy is therefore crucial for neonatal management given the varying resources and capacities of different delivery hospitals. Several models of transitional care risk assignment have been proposed to predict hemodynamic stability at birth and guide appropriate delivery plans. The Scientific Statement on the Diagnosis and Management of Fetal Cardiovascular Disease includes a comprehensive level of care and action plan grid based on anticipated risk for compromise at delivery.⁷ 

Recommendation for delivery location is informed by maternal morbidities and pregnancy complications. In the setting of fetal CHD, it will most often be driven by the need for urgent cardiac intervention for the neonate in the immediate postnatal period. Appropriate DR care requires predicting severity and understanding the resources and care teams available in the local referring hospitals. For example, a delivery hospital may have OB services but are only able to support low risk neonatal diagnostic and management requirements. Free-standing children’s hospitals generally provide a full range of neonatal care, but many do not have OB services, thus neonates requiring specialty care need to be transported. To address these highest risk deliveries, some children’s hospitals have created small special delivery units.²³⁶ Alternatively, some large academic hospital systems have fully connected adult and children’s hospitals, including delivery services providing comprehensive support for mother, fetus, and neonate. The goals of the family to deliver at their local hospital must be weighed against the fetal and neonatal risk assessment.

There is no evidence to suggest that delivery by cesarean section inherently benefits neonates with prenatally diagnosed CHD.^236,–238 However, if multiple specialized teams need to be in the DR or urgently thereafter for catheter or surgical intervention, cesarean section may be needed to assure that all teams and resources are in place. OB counseling should delineate potential risks of cesarean section and the potential benefits to the neonate.

Delivery before 39 + 0/7 weeks is associated with increased risk for adverse neonatal outcomes.²³⁹ For this reason, it has been recommended that deliveries not occur before this gestational age unless there are specific maternal indications or signs of fetal distress or hydrops fetalis.²⁴⁰ For infants with CHD, mortality rates have been shown to decrease with every advancing week of gestation from 34 to 40 weeks²⁴¹ and neonatal in hospital morbidities are improved for those born at 39 to 40 weeks, compared with late preterm or early term.²⁴² Despite this information, recent data suggests that delivery timing, mode, and neonatal length of hospital stay after prenatal CHD diagnosis remain suboptimal compared with postnatally diagnosed neonates with CHD.²⁴³ Given this, it is recommended that unless there are circumstances specific to mother or fetus, the delivery of a baby with CHD should generally occur between 39 and 40 weeks of gestation.

The majority of neonates with prenatally diagnosed CHD are expected to be hemodynamically stable. The delivery plan is determined by the maternal care needs and then routine neonatal care and outpatient cardiology follow-up care is arranged. In contrast, there are a subset of fetuses with specific critical CHD that are at significant risk for compromise during the hemodynamic transition from fetus to neonate, presenting with cardiovascular instability at birth and requiring immediate stabilization in the DR and the potential need for urgent cardiac catheterization or surgery within the first hours after birth. These critical CHD patients can be triaged using a combination of anatomic and physiologic fetal echocardiography findings, allowing for accurate risk assessment and development of appropriate delivery and coordinated postnatal care strategies.^233,234 Fetuses determined to be in the critical risk categories include d-TGA with a restrictive or closed FO and/or abnormal ductus arteriosus (DA), HLHS with a restrictive FO or intact atrial septum, total anomalous pulmonary venous return (TAPVR) with obstruction, severe Ebstein anomaly, CHB or unstable arrhythmias with significant cardiac dysfunction, or CHD, such as tetralogy of Fallot with absent pulmonary valve (TOF/APV) that has associated airway compromise because of dilation of the branch pulmonary arteries.

In the DR, newborns with severe CHD should be rapidly assessed, making note of the physiology specific to the defect. If the newborn is hypoxemic and/or there is evidence of poor perfusion, the goal is to optimize systemic oxygenation with supplemental oxygen, and intubation with mechanical ventilation if needed. In most instances, the goal should be to maintain the upper extremity pulse oximeter to ∼80% in cyanotic CHD and to >90% in acyanotic CHD. To minimize oxygen consumption, sedation and paralysis, depending on the clinical status, should be considered. If perfusion is poor, systemic cardiac output should be supported with inotropic agents. Systemic metabolic acidosis (pH <7.2) should be treated.

Neonates with ductal-dependent pulmonary or systemic blood flow require initiation of prostaglandin infusion soon after birth to prevent ductal closure. Lesions dependent on the DA for pulmonary blood flow include critical pulmonary stenosis or atresia, severe tricuspid stenosis or atresia without a significant ventricular septal defect, or tetralogy of Fallot with severe right ventricular outflow tract obstruction or pulmonary atresia, among others. Reversed orientation of the DA defined as an inferior angle of the aortic junction <90° and reversed flow at the DA (aorta to pulmonary artery) during fetal life are predictive of the need to maintain ductal patency postnatally.^244,–246 

Lesions dependent on the DA for systemic blood flow include severe coarctation of aorta, interrupted aortic arch, critical aortic stenosis, and HLHS, among others. In fetal life, reversed flow across the FO (left to right atrium) and retrograde filling of the aortic arch are predictive of the need to maintain DA patency postnatally.^247,248 The challenges of definitive prenatal diagnosis of coarctation have implications for delivery location and postnatal planning. Detailed fetal echocardiographic parameters may assist in further stratifying risk and clarifying the level of care required.^248,249 

Neonates with d-TGA are dependent on an unrestrictive FO at birth to ensure adequate mixing of the parallel systemic and pulmonary circulations. A ventricular septal defect (VSD) and patent DA may allow for some mixing; however, these shunts may not provide adequate oxygenated blood flow to the body, resulting in development of severe hypoxemia and a potentially life-threatening state.²⁵² The most reliable intervention to achieve adequate systemic oxygen delivery is to establish an atrial level shunt with BAS. Stabilization while awaiting BAS includes prostaglandin infusion, intubation and ventilation with supplemental oxygen, sedation, and volume resuscitation. Fetal echocardiogram findings that may be predictive of the need for urgent BAS include hypermobility of septum primum, bowing of septum primum into the left atrium by >50%, diminished mobility with an angle <30° between the atrial septum and septum primum, and DA abnormalities including reversed diastolic flow and/or small diameter.^42,255,256 Despite advances in prenatal diagnostic evaluation of d-TGA, the predictive value of these factors for BAS remains limited.²⁵² Therefore, all fetuses with d-TGA should be considered to be at risk for restriction of the FO postnatally with associated hemodynamic instability. In addition, prediction of postnatal persistent pulmonary hypertension in those with abnormal fetal DA size and/or flow is difficult to determine. For these reasons, a coordinated delivery is recommended for all patients.^234,235 

Neonates with HLHS are dependent on the FO to allow egress of pulmonary venous flow into the systemic circulation. Significant flow reversal of the fetal pulmonary vein pulse Doppler during the third trimester should guide DR management to include immediate access to a cardiac interventional or surgical team for urgent opening of the atrial septum by catheterization or surgery.^257,258 Extracoporeal membrane oxygenation (ECMO) may be used for initial stabilization. The use of a maternal hyperoxygenation challenge test that simulates the postnatal circulation in the third trimester may be used to predict fetuses with HLHS at risk for DR compromise.^226,251 

TAPVR is an anomalous connection of the pulmonary veins to a systemic vein. Infradiaphragmatic connections are the most common form to become obstructed. At birth, neonates with obstructed TAPVR have rapid onset of pulmonary venous congestion and cardiac failure. Obstruction of the venous pathway can be predicted by the fetal Doppler pattern with low velocity continuous flow suggesting obstruction.²⁵⁹ The only definitive therapy is surgical repair, the timing of which is dependent upon the severity of the pulmonary venous obstruction. ECMO may be used for initial stabilization if immediate surgical intervention is not available.

Fetuses with tachyarrhythmias or bradyarrhythmias may require cardiac intervention shortly after birth, especially if heart failure, fetal distress, or hydrops fetalis is present. For uncontrolled tachyarrhythmias, postnatal therapy may include medical or electric cardioversion. For fetuses with CHB, infusions of chronotropic medications, and inotropic agents if needed, should be readily available if needed for extremely low heart rates (<55 beats per minute) and/or higher heart rates with evidence of low cardiac output.^254,260 Emergent temporary pacing with an external pacemaker, transvenous lead, or epicardial lead followed by early pacemaker implantation may be required.^254,261,262 

Tetralogy of Fallot with absent pulmonary valve (TOF/APV) and severe Ebstein’s anomaly of the tricuspid valve both represent a spectrum of rare critical CHD characterized by right-sided volume overload and heart failure, massive cardiomegaly, and risk for hydrops fetalis.^263,–265 Cardiomegaly may have a negative impact on fetal lung development. In addition, those with TOF/APV are at risk for tracheobronchial compression from the dilated proximal pulmonary arteries. As a result, newborns with TOF/APV or Ebstein’s anomaly may have difficulty transitioning in the DR because of difficulties with ventilation. In addition, patients with Ebstein’s anomaly have a higher incidence of ventricular pre-excitation and supraventricular tachyarrhythmias.²⁶⁶ Mortality is high in both with a reported risk of perinatal mortality up to 42% for TOF/APV and 45% for severe Ebstein’s anomaly.^264,267 Management of these high risk patients starts in-utero with close fetal monitoring, assessing for worsening cardiovascular status to determine timing of delivery. A coordinated delivery and postnatal care plan should be in place in anticipation of poor cardiac output, respiratory failure, and/or arrhythmias.^{233,–235,268} The management goals in the immediate postnatal period include supporting cardiac output, and if hypoxemia is present, improving oxygenation and decreasing pulmonary vascular resistance which may decrease afterload on the right ventricle. Postnatal care teams should be prepared to provide respiratory support in the delivery room, including intubation, and ventriculation using supplemental oxygen if hypoxemia is present. In Ebstein’s anomaly, the presence of tricuspid insufficiency as well as a patent pulmonary valve with pulmonary insufficiency results in a “circular shunt,” which leads to severely decreased systemic cardiac output. The DA in this case may be detrimental and therefore PGE1 is not indicated. Pharmacologic or intervention to close the DA may be considered.^269,270 

1. Delivery planning:

   • Delivery should be planned ideally between 39 and 40 weeks gestation unless there are maternal or fetal indications for an early delivery (Class I, LOE B-NR)

2. Cesarean section should not be performed in the absence of OB indications, though in rare cases may be beneficial to ensure availability of appropriate personnel for intervention in immediate postnatal period (Class I, LOE B-NR)

• Newborns with severe CHD should be rapidly assessed in the DR, making note of the physiology specific to the defect. If the newborn is hypoxemic and/or there is evidence of poor perfusion, the goal should be to optimize systemic oxygenation, minimize oxygen consumption and support systemic output. (Class I, LOE C-LD)

• Fetal diagnosis allows for specialized care for high risk CHD, specifically:

  • For ductal dependent CHD, prostaglandin infusion should be initiated soon after birth (Class I, LOE B-NR)

  • For d-TGA, prostaglandin infusion should be initiated, and if hypoxemia is present and there is a restrictive or closed FO, an urgent BAS should be performed. Stabilization while awaiting BAS may include intubation and ventilation with supplemental oxygen, sedation, and volume resuscitation (Class I, LOE B-NR)

  • For HLHS and a restrictive FO or intact atrial septum, prostaglandin infusion should be initiated, and preparations made for urgent transfer to the cardiac catheterization laboratory or the operating room for atrial septoplasty. ECMO may be needed for stabilization before intervention if severe hypoxemia and acidemia is present (Class I, LOE B-NR)

  • For TOF/APV or severe Ebstein’s anomaly, if hypoxemic, intubation and ventilation with supplemental oxygen should be initiated to maintain oxygenation (Class I, LOE C-EO)

  • For obstructed TAPVR, delivery should occur in or close to the cardiac center with plans made for immediate reparative surgery or ECMO support in the event of cardiovascular collapse (Class I, LOE C-EO)

  • For tachyarrhythmias with heart failure or hydrops fetalis, electrical cardioversion or antiarrhythmic medication should be initiated in the DR (Class I, LOE B-NR)

  • For bradycardia because of CHB with heart failure or hydrops fetalis, medical treatment with a chronotropic agent should be initiated in the DR and preparations for immediate pacing considered (Class I, LOE C-EO)

Prenatal diagnosis of congenital cardiovascular disease allows for more informed prenatal counseling regarding diagnosis, prognosis, potential fetal interventions when appropriate, and improved postnatal planning and DR management. Identification of fetuses requiring in-utero intervention or specialized DR care allows creation of detailed fetal and delivery recommendations tailored for the specific lesions. The prediction of postnatal compromise remains challenging for some defects. For these, diagnostic models using fetal echocardiography and other tools, such as MRI and maternal hyperoxia testing, in select diagnoses may be beneficial. Only by improving detection, identifying risk factors for progression of disease, investigating novel fetal intervention strategies, and creating coordinated multidisciplinary DR care plans will outcomes improve.

BAS

balloon atrial septostomy

CVP

cardiovascular profile

CHB

complete congenital heart block

CHD

congenital heart disease

DR

delivery room

d-TGA

dextro-transposition of the great arteries

DA

ductus arteriosus

LOE

Level of Evidence

FISH

fluorescent in-situ hybridization

FO

foramen ovale

HLHS

hypoplastic left heart syndrome

IFCIR

International Fetal Cardiac Intervention Registry

TAPVR

total anomalous pulmonary venous return