Pattern of pulmonary venous blood flow in the hypoplastic left heart syndrome in the fetus

Labyrinthine cor triatriatum sinister in fetal hypoplastic left heart syndrome is associated with poor outcomes

OBJECTIVES

A subset of hypoplastic-left-heart-syndrome (HLHS) fetuses have a complex cor-triatriatum sinister that we named "labyrinthine-cor (L-cor)". We sought to determine the prevalence of L-cor in HLHS fetuses and hypothesized that it is associated with increased mortality.

METHODS

This single-center retrospective cohort study included all HLHS fetuses from January 2010-December 2020. Fetuses with other hypoplastic-left-heart variants, inadequate images, lack of follow-up and fetal atrial-septal interventions were excluded. RAS was defined as the ratio of pulmonary-vein forward-to-reverse velocity-time-integral (VTI) ≤ 5 and severe-RAS defined as VTI-ratio <3. Kaplan-Meier survival-analysis was performed for the primary outcome of transplant-free survival for 62 weeks after gestational-age of 30 weeks (∼1 year).

RESULTS

Of the 156 consecutive fetuses with HLHS, 11 (7.7%) had L-cor and 8/11 (72.7%) of these had RAS. When compared to HLHS-RAS without L-cor, fetuses with HLHS-RAS and L-cor were less likely to survive to 28 days (87% vs. 62.5%, p = 0.017) and to 1 year (69.6% vs. 25%, p = 0.029). When comparing by survival analysis, fetuses with severe-RAS with L-cor had lower survival compared severe-RAS without L-cor (p = 0.020).

CONCLUSION

L-cor in fetal HLHS is associated with increased mortality. Recognition of this finding is important for prognostication and atrial-septal-intervention planning.

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.

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.

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.

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.

Risk stratification of patients with hypoplastic left heart syndrome and intact atrial septum using fetal MRI and echocardiography

Despite prenatal diagnosis, prenatal intervention, and immediate postnatal intervention, patients with hypoplastic left heart syndrome and intact or highly restrictive atrial septum have the highest risk for mortality. Charts for all infants diagnosed with hypoplastic left heart syndrome from 2009 to 2017 were retrospectively reviewed and compared, including pulmonary vein Doppler patterns on fetal echocardiogram and evidence of pulmonary lymphangiectasia on fetal MRI. Of the 81 newborns with hypoplastic left heart syndrome, we defined two groups. Group 1 patients had an adequate atrial septal communication (n = 69), while Group 2 met criteria for intact/restrictive septum (n = 12). No patient in Group 1 had a type C pulmonary vein Doppler pattern, while no patient in Group 2 had a type A pulmonary vein Doppler pattern. The two patients with pulmonary lymphangiectasia had type C pulmonary vein Doppler pattern and an intact atrial septum and did not survive. Survival to discharge for Group 1 was 83% compared to 58% for Group 2 (p = 0.116). Survival to stage 2 palliation was 71% for Group 1 compared to 50% for Group 2 (p = 0.186). Only 4 of the initial 12 patients from Group 2 are alive, which is an overall survival of 33%. Our experience supports previous evidence that fetal echocardiography can identify those patients with the greatest likelihood for postnatal intervention as well as those at highest risk for mortality. Fetal MRI is a novel imaging modality that may help providers separate patients at highest risk for mortality, regardless of pulmonary vein Doppler pattern.

Ultrasound evaluation of fetal critical aortic stenosis using the left atrium area/cardiac area ratio and the Doppler patterns in the pulmonary veins

In fetal critical aortic stenosis (AS), a double reverse pattern in the pulmonary veins (PVs) is associated with a poor prognosis. We evaluated the hemodynamic changes using PV Doppler and the left atrium area/cardiac area (LA/CA) ratio in a fetus at 28 weeks of gestation with critical AS complicated with hydrops fetalis, polyhydramnios, and cardiac abnormality. A markedly enlarged LA and severe mitral regurgitation with critical AS were detected, with LA/CA ratio = 0.40 and double reverse pattern with forward/reverse velocity time integral ratio (FRVR) = 1.18 on PV Doppler. After amniotic reduction at 31 weeks, the LA/CA ratio decreased (0.24) and the FRVR in PV increased (7.11). Forward flow through the fetal aorta was seen spontaneously, and hydrops fetalis was relieved with LA volume reduction. A male neonate weighing 2171 g was delivered via cesarean section at 36 weeks with an Apgar score of 5 and 6 at 1 and 5 min, respectively. He required atrial septal opening and bilateral pulmonary artery banding after birth, followed by Norwood operation. The double reverse pattern in PVs might be reversible. The change in FRVR in PVs and LA/CA ratio would be helpful in understanding the hemodynamic change in fetal critical AS.

EDUCATIONAL SERIES IN CONGENITAL HEART DISEASE: Prenatal diagnosis of congenital heart disease

This review article will guide the reader through the background of prenatal screening for congenital heart disease. The reader will be given insight into the normal screening views, common abnormalities, risk stratification of lesions and also recent advances in prenatal cardiology.

Circulating mRNA in Maternal Plasma at the Second Trimester of Pregnancy: A Possible Screening Tool for Cardiac Conotruncal and Left Ventricular Outflow Tract Abnormalities

OBJECTIVE

Maternal plasma is a source of circulating placental nucleic acids. This study was designed to detect aberrantly expressed placental mRNA genes circulating in the maternal plasma of pregnancies affected with fetal conotruncal anomalies (CNTRA) and left-ventricular outflow tract (LVOT) obstruction in the second trimester of pregnancy.

METHODS

This was a retrospective monocentric study conducted from 1 Jan 2016 to 31 Dec 2016. NanoString technology was used to identify aberrantly expressed genes, comparing 36 women carrying a fetus with CNTRA or LVOT obstruction to 42 controls at 19-24 weeks of gestation. The genes with differential expression were subsequently tested using real-time polymerase chain reaction. Linear discriminant analysis was used to combine all the mRNA species with discriminant ability for CNTRA and LVOT obstruction. A multivariable receiver operating characteristic (ROC) curve having the estimated discriminant score as an explanatory variable was generated for the two affected groups versus controls.

RESULTS

Three genes with differential expression, namely MAPK1, IQGAP1 and Visfatin were found. The ROC curves yielded detection rates of 60 and 62.5% at a false-positive rate of 5% for CNTRA and LVOT, respectively.

CONCLUSIONS

These data suggested that molecular screening of CNTRA and LVOT obstruction in the second trimester is feasible. Prospective studies are needed to test the discriminant ability of these genes and to calculate the predictive positive value in the general population.

Challenges and controversies in fetal diagnosis and treatment: hypoplastic left heart syndrome

Today, almost 70% of babies with hypoplastic left heart syndrome (HLHS) will survive into adulthood, although significant long-term morbidity and mortality still exists. Prenatal diagnosis of HLHS is increasingly common, allowing improved counseling, and the potential for fetal intervention if indicated. Exciting progress continues to be made in the area of fetal diagnosis and intervention, specifically catheter intervention for intact atrial septum or severe aortic stenosis. Pediatric cardiologists should be keenly aware of the flaws of staged palliation for the treatment of HLHS, and need to keep abreast of the emerging data regarding fetal diagnosis and intervention.

The use of reconstructive surgery to improve quality of life and survival in prenatal hypoplastic left heart syndrome

Outcomes for hypoplastic left heart syndrome have improved substantially in the era of prenatal diagnosis. Current stage 1 survival rates are in excess of 90% in the absence of risk factors. However, fetuses with an intact atrial septum continue to have poor postnatal survival. Accurate diagnosis of these fetuses with an intact atrial septum relies upon careful assessment of the patent foramen ovale, pulmonary venous Doppler flow patterns and branch pulmonary artery Doppler flow patterns. Prenatal and perinatal interventions, such as the placement of an atrial stent in utero or delivery at a center where a stent may be placed immediately after birth to relieve left atrial hypertension, may improve survival in this particularly high-risk group.

Rationale for and current status of prenatal cardiac intervention

The idea of prenatal intervention in congenital heart defects was put forward over 20 years ago, arising from the observation that some forms of cardiac malformation progressed in severity as pregnancy advanced. The simultaneous development of minimally invasive catheter techniques in children, led to the concept of treating the foetal heart directly, in an attempt to prevent the changes which had been observed. Early efforts at prenatal valvuloplasty were largely set aside after poor results and the coincidental development of alternative, increasingly successful, postnatal surgical strategies. However, in the last 10 years or so, some centres have revived and extended the interventional techniques, with some success. The application of these techniques is limited to very few conditions, and suitable cases are relatively uncommon. Exploration of these procedures, therefore, should be limited to very few centres and the results should be closely scrutinised before this becomes an accepted management option.

Prenatal diagnosis of atrial restriction in hypoplastic left heart syndrome is associated with decreased 2-year survival

OBJECTIVE

To compare the course of hypoplastic left heart syndrome (HLHS) patients diagnosed prenatally with any degree of atrial restriction with those without evidence of atrial restriction.

DESIGN

Retrospective, cohort.

METHODS

Prenatally diagnosed HLHS patients from August 1999 to January 2009 were categorized as nonrestrictive versus restrictive, defined by left atrial hypertension on pulmonary venous Doppler and/or an intact interatrial septum.

RESULTS

Of 73 total fetal patients identified, 49 were live-born. Survival at 2 years was 29/35 [83% confidence interval (CI): 59.5%-88.9%] for the nonrestrictive group and 6/14 (43% CI: 17.7%-6.0%) for the restrictive group (p<0.0001). Of those who underwent stage 1 palliation (35 with nonrestrictive and 10 with restrictive atrial septa), both groups had a similar incidence of preoperative acidosis and need for ventilation and inotropic support. Postoperatively, there was no difference between groups in ventilator days, length of stay, or survival to discharge. There was decreased survival at 2 years in the restrictive group, 60% (CI: 26.2%-87.8%) versus 83% (CI: 66.4%-93.4%) in the nonrestrictive group. Furthermore, a disproportionate number of interstage deaths was evident in the restrictive group.

CONCLUSIONS

Prenatal presence of any degree of atrial septal restriction in the setting of HLHS confers a significant survival disadvantage, with increases in both early and late mortality.

Evaluation of normal fetal pulmonary veins from the early second trimester by enhanced-flow (e-flow) echocardiography

OBJECTIVES

To explore the feasibility of using enhanced-flow (e-flow) imaging technology to identify fetal pulmonary veins and establish gestational age-specific reference values at 12-40 weeks' gestation.

METHODS

The pulmonary venous internal diameter, peak systolic and diastolic flow velocities and visualization rate were analyzed in 332 normal fetuses at 12-40 weeks of gestation. Two-dimensional gray-scale (2D) ultrasound, color Doppler and e-flow imaging were used to detect the pulmonary veins in the four-chamber view by taking the lung as the penetration window.

RESULTS

The pulmonary veins could be visualized as early as 12 weeks' gestational age by e-flow imaging. The right and left pulmonary venous internal diameters and peak systolic and diastolic flow velocities increased with increasing gestational age. Between 12 and 40 gestational weeks, the internal diameter and both the systolic and diastolic flow velocities of the fetal right pulmonary vein were significantly larger than were those of the left vein (P < 0.05). Of 118 fetuses at 12-22 gestational weeks, the visualization rate of the four pulmonary veins (left superior and inferior, right superior and inferior) was 5.9% (7/118) by 2D ultrasound, 41.5% (49/118) by color Doppler and 61.9% (73/118) by e-flow imaging. The visualization rate by e-flow imaging was significantly higher than that using the other two techniques (P < 0.001).

CONCLUSION

e-flow imaging is apparently a feasible and promising technology with which to identify the fetal pulmonary veins in the early stages of the second trimester.

Vasoreactive response to maternal hyperoxygenation in the fetus with hypoplastic left heart syndrome

BACKGROUND

Cardiopulmonary interactions play an important role in the pathophysiology of hypoplastic left heart syndrome (HLHS). Pulmonary vasculopathy has been identified, especially in those with restrictive/intact atrial septum. Responsiveness of the pulmonary vasculature to maternal hyperoxygenation (MH) may provide a tool to assess the degree of pulmonary vasculopathy present before birth.

METHODS AND RESULTS

Doppler echocardiography was performed in 27 normal and 43 HLHS fetuses. In HLHS, sampling was repeated after 10 minutes of MH with 60% FiO(2) and after 5 minutes of recovery. Sampling was performed in the proximal, midportion, and distal branch pulmonary artery (PA). Pulsatility index (PI) was used as a measure of vascular impedance. Of the HLHS fetuses, 34 had an open interatrial septum and 9 had a restrictive/intact atrial septum. At birth, 5 fetuses underwent immediate intervention on the interatrial septum. Middle cerebral artery PI was lower in HLHS versus normal fetuses (P<0.001). There was no difference in UA, DA, or branch PA PI between normal fetuses and those with HLHS. MH led to a significant decrease in PI at each of the PA sites sampled in fetuses with an open atrial septum (P<0.001); however, there no was significant change in the PI in fetuses that required immediate intervention on the atrial septum at birth. Using a cutoff value of <10% vasoreactivity, the sensitivity of MH testing for determining need for immediate intervention at birth is 100% (0.46 to 1.0); specificity, 94% (0.78 to 0.99); positive predictive value, 71% (0.30 to 0.95); and negative predictive value, 100% (0.86 to 1.0). No untoward effects were seen with MH.

CONCLUSIONS

PA vasoreactivity to MH occurs in the fetus with HLHS. MH testing accurately identifies fetuses requiring urgent postnatal intervention at birth and may be used to select candidates for fetal atrial septoplasty.

Behavior of pulmonary venous flow during fetal respiratory movements

OBJECTIVE

To test the hypothesis that fetal pulmonary venous flow pulsatility index is lower during fetal respiratory movements than in apnea.

DESIGN

Case control. SETTINGS/PATIENTS: Twenty-two normal fetuses of mothers without systemic disease were examined in apnea (controls) and in the presence of fetal respiratory movements (cases). Fetuses were examined by prenatal Doppler echocardiography with color flow mapping. The pulsatility index of the pulmonary vein was obtained by placing the pulsed Doppler sample volume over the right upper or left lower pulmonary vein, and calculating the ratio (maximum velocity [systolic or diastolic]-presystolic velocity/mean velocity).

RESULTS

Mean gestational age was 28.9 +/- 2.9 weeks. During fetal apnea, mean systolic, diastolic, and presystolic velocities were, respectively, 0.35 +/- 0.08 m/s, 0.26 +/- 0.07 m/s, and 0.09 +/- 0.03 m/s. In the presence of fetal respiratory movements, mean systolic, diastolic, and presystolic velocities were, respectively, 0.33 +/- 0.1 m/s, 0.28 +/- 0.08 m/s, and 0.11 +/- 0.04 m/s. Pulsatility index pulmonary vein in apnea was 1.25 +/- 0.23 (1.69 to 0.82), and during fetal respiratory movements it was 0.97 +/- 0.2 (1.53 to 0.61).

CONCLUSION

We showed a significant reduction in impedance of pulmonary venous flow, represented by pulmonary vein pulsatility index, during fetal respiratory movements, reflecting modifications of the left atrial dynamics and enhancement of left ventricular compliance.

Hypoplastic left heart syndrome diagnosed in fetal life: associated findings, pregnancy outcome and results of palliative surgery

OBJECTIVES

To analyze the main prenatal characteristics of hypoplastic left heart syndrome (HLHS), its association with extracardiac anomalies including increased nuchal translucency (NT) and the outcome of affected patients.

METHODS

We searched our database for classical forms of HLHS (aortic atresia, mitral and aortic atresia and critical aortic stenosis evolved to a severely hypoplastic left ventricle) prenatally diagnosed between 1998 and 2006. Data on 101 fetuses were retrieved and analyzed.

RESULTS

The main reason for referral was suspected heart defect on a routine ultrasound scan (82%). The mean gestational age at diagnosis was 21 weeks. Most cases were detected at < or = 22 weeks (72%), the upper limit for termination of pregnancy (TOP) in our country (Spain). An intact atrial septum was diagnosed in 11 of the 58 fetuses (19%) in which pulmonary vein blood flow was assessed, and this diagnosis was proved to be correct in the six liveborn babies. Most fetuses (68%) had an isolated HLHS. Fourteen fetuses (14%) were chromosomally abnormal and all had associated extracardiac defects. NT was above the 95th centile in 21 of the 74 cases (28%) in which this measurement was available. 79% (58/73) of the cases in which HLHS was detected at < or = 22 weeks were terminated, and no differences in the rate of TOP were found through the study period. Among the 43 continuing pregnancies, seven fetuses died in utero and there were 36 live births; in 12 cases the parents opted for compassionate care and 24 chose to have the infant surgically treated. In the cohort of intention-to-treat cases, the overall survival rate was 36% (9/25). This rate improved from 18% (2/11) in the period 1998-2002 to 50% (7/14) in 2003-2006. There were no survivors in cases with intact atrial septum or when there were associated defects. At follow-up, 2/9 survivors suffered from significant neurological morbidity.

CONCLUSIONS

Fetal echocardiography allows an accurate diagnosis of HLHS, which is made in most instances in the first half of pregnancy. Despite the advantage offered by the prenatal detection of HLHS, which provides the opportunity to plan perinatal management, our up-to-date results show that the outlook for these fetuses is still poor, and highlight the importance of presenting these figures when counseling parents with affected fetuses.

CURRENT ASPECTS OF FETAL CARDIOVASCULAR FUNCTION

Investigation of fetal cardiac function remains a challenging task. Although the response of the heart to changes in load is well-known in animal models and the adult human, the developmental changes in fetal cardiac response remain poorly characterised. However, quantitative evaluation of cardiovascular function is important to predict the clinical course and to manage the fetus optimally. To date, the routine evaluation of fetal cardio vascular function has relied largely on Doppler echocardiography which enables an estimate of haemodynamics; newer modalities such as measurement of myocardial velocities are employed less routinely. Fetal magnetic resonance imaging still lacks the resolution necessary to contribute significantly to morphological or functional assessment of the fetal cardiovascular system.

Fetal intervention for cardiac disease: the cutting edge of perinatal care

Fetal cardiac valvuloplasty has been proposed for progressive cardiac disease with a poor prognosis, such as critical aortic stenosis and pulmonary atresia with intact ventricular septum and balloon atrial septostomy for hypoplastic left heart syndrome, or simple transposition of the great arteries with closed or restrictive inter-atrial communication. It is anticipated that early rescue of ventricles or the pulmonary veins from an unfavourable environment may promote healthier ventricular and vascular growth and improve postnatal outcomes. While close collaboration between the fetal medicine specialist and perinatal cardiologist may optimize the chances of technical success, obstacles to progress include the relative rarity of suitable cases and late referral for therapy. In common with other interventions in fetal medicine, there is a learning curve, and it would benefit progress if the procedures were initially concentrated in just a few centres to enable them to develop skills and experience. Following careful evaluation, it may then be desirable to train further centres and roll out best practice models.

Functional assessment of the evolution of congenital heart disease in utero

PURPOSE OF REVIEW

This article reviews recent developments in the assessment of changes in structure and function in the fetal heart with the focus on congenital heart disease malformations.

RECENT FINDINGS

Use of the combination of the cardiovascular profile score, the biophysical profile score and additional physiological measurements with Doppler echocardiography have allowed better characterization of disease states and the changes that can occur in utero during the last two trimesters of gestation.

SUMMARY

A comprehensive examination of the structure and function of the fetal heart together with the evaluation of other parameters of fetal wellbeing are necessary for comprehensive assessment of the evolution of congenital heart disease in utero. Only such an objective surveillance can elucidate the pathophysiology and natural history, guide appropriate timing of intervention, monitor the success of any in-utero therapy, and predict perinatal outcome.

Hypoplastic Left Heart Syndrome With Intact or Highly Restrictive Atrial Septum: Surgical Experience From a Single Center

BACKGROUND

The presence of an intact or highly restrictive atrial septum (I/HRAS) has long been recognized as a predictor of poor outcome among patients with hypoplastic left heart syndrome (HLHS), although the rarity of this condition has precluded conclusive study. The purpose of this review is to summarize recent surgical outcomes for these patients at our center and to identify predictors.

METHODS

We retrospectively identified all neonates with a diagnosis of HLHS and I/HRAS who underwent stage I palliation at Children's Hospital Boston between January 2001 and December 2006. Chart review enabled analysis of patient and procedural variables.

RESULTS

All 32 patients underwent left atrial decompression in utero or postnatally before surgery. Fourteen patients (44%) underwent fetal intervention, either atrial septoplasty (n = 9) or aortic valvuloplasty (n = 5). Twenty-nine of the 32 patients had postnatal left atrial hypertension and underwent transcatheter atrial septoplasty as neonates before surgery; 3 did not require postnatal atrial septoplasty after successful fetal atrial septoplasty. After stage I, hospital survival was 69% (22 of 32). Need for shunt revision (p = 0.02) and for extracorporeal membrane oxygenation use (p < 0.001) were associated with hospital mortality. Survival at 6 months was 69% for patients who had fetal intervention, and 38% for those who were treated only postnatally (p = 0.2).

CONCLUSIONS

Surgical outcome for patients with HLHS and I/HRAS continues to improve. Prenatal decompression of the left atrium may be associated with greater hospital survival. Proposed effects of fetal intervention on lung pathology and longer-term survival are subjects for future study in this unique group of patients.

Hypoplastic left heart syndrome with intact atrial septum: case report

OBJECTIVES

Hypoplastic left heart syndrome (HLHS) with an intact atrial septum (IAS) is a rare finding, reported in only 1% of pathologic specimens with hypoplasia of the aortic tract complex. In newborns with left heart obstruction, the existence of an interatrial communication is very important for oxygenated blood to be distributed to the body and to prevent pulmonary congestion. The ability to predict prenatally restriction of the atrial defect may allow earlier surgery to be planned.

METHODS

We report a case of prenatal diagnosis of HLHS with a complete premature closure of the foramen ovale that was not detected by prenatal echocardiography.

RESULTS AND CONCLUSION

The management of neonates with HLHS in the first days of life is crucial to the results of the first stage of the Norwood procedure. We suggest that delivery of the mother close to surgical centre and avoiding neonatal transfer improve the results, but stabilisation with prostaglandins and balancing of the systemic and pulmonary resistances are also important. A restrictive or closed atrial septal defect may contribute to haemodynamic instability in the first days of life. The ability to predict this complication prenatally may help in the immediate postnatal management of the affected infant.

Changes in pulmonary venous Doppler parameters in fetal cardiac defects

OBJECTIVES

Recent observations in pediatric cardiological studies have prompted discussion on the possible role of intrauterine pulmonary venous changes in neonatal and postoperative outcome of infants with congenital heart defects. This study analyzes changes of Doppler blood flow velocity waveforms in the pulmonary veins of fetuses with different cardiac defects.

METHODS

Eighty fetuses (mean gestational age, 27 weeks) with prenatally diagnosed cardiac defects were classified into one of five groups: obstructed left atrium, other left ventricular outflow tract obstruction, right ventricular outflow tract obstruction, miscellaneous cardiac defects and total anomalous pulmonary venous drainage. Doppler examination of the pulmonary veins was performed and the time velocity integral (TVI), end-diastolic (A) velocity, and pulsatility index for veins (PIV) were compared with reference ranges.

RESULTS

Fetuses with infradiaphragmatic total anomalous pulmonary venous drainage showed a continuous Doppler flow pattern instead of the typical pulsatile waveform pattern. In fetuses with obstructed left atrium and restrictive foramen ovale, a reversed A-velocity and increased PIV were found. In five of the eight fetuses with left outflow tract obstruction but patent mitral valve, PIV was increased. In the other groups there were no obvious changes in Doppler parameters.

CONCLUSIONS

We suggest routine examination of the pulmonary veins with pulsed Doppler ultrasound in every fetus with a prenatally diagnosed heart defect. Such Doppler parameters could be used in future as cut-offs for the recently reported in-utero atrial septostomy to decompress an obstructed left atrium.

Catheter-based decompression of the left atrium in patients with hypoplastic left heart syndrome and restrictive atrial septum is safe and effective

Infants with hypoplastic left heart syndrome (HLHS) and restrictive or intact atrial septum (rAS) present with cyanosis, pulmonary edema, and are critically ill. A previous report from our institution on emergent Norwood for HLHS with rAS showed 10% survival. We hypothesized that transcatheter left atrial (LA) decompression in HLHS with rAS would safely and effectively relieve LA hypertension, improve oxygenation, and improve Norwood survival. Between 1996 and 2004, 30 patients with HLHS and rAS underwent cardiac catheterization for pre-Norwood intervention. Twenty-eight atrial septostomies were performed: 23 static balloon dilations, 4 Rashkind septostomies, and 1 intra-atrial stent. Two procedures were aborted due to perforation (n = 1) or inability to enter the LA (n = 1). Eight total patients required surgical septectomy, for a failure rate of 27%. There were no catheter-related mortalities, although two patients died within 36 hr of the procedure after surgical septectomy. Major complications occurred in three patients (10%)--atrial perforations requiring intervention. Mean atrial septal defect gradient fell from 16.7 +/- 4.9 to 6.3 +/- 3.4 mm Hg (P < 0.001; n = 18). Mean LA pressure dropped from 21.8 +/- 5.5 to 13.1 +/- 6.5 mm Hg (P < 0.001; n = 16). Mean PaO(2) rose from 29.5 +/- 9.1 to 36.5 +/- 5.1 torr (P < 0.001; n = 23). Seventeen of 30 patients (57%) survived to discharge from Norwood. Thirteen have undergone hemi-Fontan and nine Fontan. Sixteen of 22 successful decompressions (73%) survived to discharge. Transcatheter decompression of the LA for patients with HLHS and rAS can be performed safely, reduces the transatrial gradient, and improves oxygenation. Catheter intervention improves survival compared to historical controls undergoing emergent Norwood.

Progression of fetal heart disease and rationale for fetal intracardiac interventions

The outcome of cardiac disease diagnosed before birth is paradoxically worse than that diagnosed postnatally. In part, this is because fetal screening detects cases that are already showing failure of cardiac growth which are usually progressive with secondary damage to the myocardium, lungs and brain. Fetal valvuloplasty has been proposed for cases of critical aortic and pulmonary stenosis or atresia, and atrial septostomy for a restrictive oval foramen associated with aortic stenosis, hypoplastic left heart syndrome and transposition of the great arteries. The rationale for fetal therapy is to restore forward flow and reduce intraventricular pressure, thus improving coronary perfusion and minimizing ischaemic damage. Successful valvuloplasty has reduced systemic venous pressures and reversed fetal hydrops, thus prolonging pregnancy. It has resulted in improved ventricular growth in some cases and spontaneous opening of a closed oval foramen with normalization of pulmonary venous waveforms. These signs suggest better fetal cardiopulmonary development and improved surgical outcomes.

Predictive value of fetal pulmonary venous flow patterns in identifying the need for atrial septoplasty in the newborn with hypoplastic left ventricle

BACKGROUND

Pulmonary venous Doppler (PVD) flow patterns in the fetus with hypoplastic left heart syndrome (HLHS) have been correlated with restrictive interatrial communication or intact atrial septum (RAS) postnatally; however, the ability of PVD to identify the neonate requiring emergent atrial septoplasty (EAS) for severe left atrial hypertension and hypoxemia has not been critically evaluated. It was the purpose of this study to determine the predictive power of fetal PVD in identifying the need for EAS in newborns with HLHS and RAS.

METHODS AND RESULTS

Forty-one patients with fetal PVD flow analysis and postnatally confirmed HLHS were studied. Pulsed-wave assessment of PVD flow included S-, D-, and A-wave velocity, time-velocity integral (VTI) of forward and reverse flow, and S/D velocity and forward/reverse VTI ratio. Neonatal EAS was used as the primary clinical outcome variable. Receiver operating characteristic curves were used to determine cutpoints at which PVD indices best predicted EAS. Cutpoints were evaluated for clinical accuracy and usefulness by use of Bayesian analysis. Eight of 41 subjects underwent EAS. Need for EAS was most accurately predicted by forward/reverse VTI ratio <5 (sensitivity, 0.88, 95% CI, 0.49 to 0.99; specificity, 0.97, 95% CI, 0.82 to 0.99), which, when present, increases the posttest likelihood of EAS to 74%, assuming a pretest prevalence of 10%. Accuracy and usefulness of other PVD indices were affected by false-positive results.

CONCLUSIONS

In the fetus with HLHS, a PVD forward/reverse VTI ratio of <5 is the strongest predictor of the need for EAS in the newborn period. These observations should improve our ability to identify and expectantly manage the fetus with HLHS and RAS.

Diagnosis and management of restricted or closed foramen ovale in fetuses with congenital heart disease

The incidence of foramen ovale restriction or closure is greater in fetuses with congenital heart defects (CHDs) and obligate atrial shunting and/or left atrial hypertension. Foramen ovale restriction or closure in fetuses with CHD can cause distress in utero or at birth. We suggest performing serial ultrasound assessment for at-risk fetuses with CHD to best assure fetal well-being plan the timing and mode of delivery, and develop management protocols for in utero and postnatal care. The future for these patients may be more optimistic as fetal intervention procedures are developed and mastered.

Intrauterine pulmonary venous flow and restrictive foramen ovale in fetal hypoplastic left heart syndrome

OBJECTIVES

We sought to determine whether direct foramen ovale (FO) assessment or pulmonary venous (PV) flow patterns in fetal hypoplastic left heart syndrome (HLHS) correlate with clinical markers of postnatal left atrial (LA) hypertension severity associated with restrictive FO.

BACKGROUND

Restrictive FO places a newborn with HLHS at high risk of mortality and morbidity.

METHODS

We reviewed the prenatal and postnatal echocardiograms and outcomes of 45 fetuses with variants of HLHS diagnosed since May 1999 to determine whether direct FO assessment or PV flow patterns correlate with clinical LA hypertension after birth.

RESULTS

Direct FO assessment in utero showed a poor correlation with postnatal FO size, Pao(2), base excess, and the need for atrial septoplasty (p > 0.05). In 40 fetuses with available PV spectra, three PV flow patterns were observed: 1). continuous forward flow with a small a-wave reversal (velocity time integral [VTI] for reverse/forward flow [VTIR/VTIF ratio <0.18]); 2). continuous forward flow with increased a-wave reversal (VTIR/VTIF ratio >or=0.18); and 3). brief to-and-fro flow. Among 19 live-borns, the postnatal FO diameter was smaller in patients with type B than in those with type A flow (1.6 +/- 1.6 mm and 4.5 +/- 2.1 mm, respectively; p = 0.0015), and all patients with type C flow had an intact atrial septum. All three patients with type C flow were critically ill at birth, requiring emergent atrial septoplasty, and two died after heart transplantation, whereas patients with type A or B flow were clinically stable, with only one postoperative death.

CONCLUSIONS

Prenatal PV flow patterns in HLHS identify the fetus at risk of severe LA hypertension at birth.

Evolution of heart disease in utero

Cardiac embyogenesis occurs in the first 6 to 7 weeks of human development. Although it is during this time that many of the major cardiovascular defects develop, many of these lesions continue to evolve and others develop in the latter half of gestation. There may be development or progression of ventricular inflow or outflow tract and arch obstruction, and ventricular or great artery hypoplasia. There may be progressive antrioventricular or semi-lunar valve regurgitation which can compromise the fetal circulation. There may be development of dysrhythmias, primary myocardial disease and heart failure. The fetal shunts, the foramen ovale and ductus arteriosus, may change in form and function. Finally, cardiac tumors may develop, grow, or regress. Knowledge of the mechanisms of and potential for progression in fetal heart disease is critical for counseling regarding prognosis and for planning of prenatal and neonatal management.

Echocardiographic evaluation of cardiac function in the fetus

The development of high-resolution ultrasound has allowed detailed examination of the fetal heart. The accuracy of fetal echocardiography in the diagnosis of malformations of the fetal heart has been established in the second trimester and, more recently, at a much earlier stage in gestation (Allan et al., 1980; Allan et al., 1981; Simpson, 2000; Huggon et al., 2002). Confirmation of structural abnormalities has usually been by autopsy or by postnatal investigation. This is certainly sufficient for confirmation of structural malformations, but functional evaluation of the fetal heart is far more difficult to validate. Post-mortem studies, by their very nature give little insight into cardiac function and postnatal studies, whilst permitting functional evaluation of the heart, do so under entirely different conditions compared to the circulation in utero. Prior to the advent of ultrasound, fetal data was drawn from invasive animal studies (Pohlman, 1909; Dawes et al., 1954; Barcroft, 1936; Rudolph, 1985). There have been very few invasive studies in the human fetus including some conducted on exteriorised fetuses undergoing termination by hysterotomy (Nyberg and Westin, 1962; Rudolph et al., 1971). Pressure data has been obtained from the human fetus for normal human hearts and in cardiac disease (Johnson et al., 2000; Johnson et al., 1992; Johnson, 1992). However, the vast majority of cardiac functional data in the human fetus has been obtained by non-invasive means, which has almost exclusively been by echocardiography. This article will review some of the techniques that may be used to evaluate fetal cardiac function and will also emphasise some of the limitations of such techniques.

Reference ranges for Doppler-assessed pulmonary venous blood flow velocities and pulsatility indices in normal human fetuses

OBJECTIVES

To establish reference ranges with gestation for Doppler parameters of fetal pulmonary venous blood flow during the second half of pregnancy, including not only peak velocities, but also relative indices reflecting left atrial pressure changes.

METHODS

In this cross-sectional study, 114 normal singleton pregnancies between 19 and 37 weeks' gestation were examined by Doppler echocardiography. In 98 fetuses, peak systolic velocity (S), peak diastolic velocity (D), end-diastolic velocity (A), and time velocity integral (TVI) were measured, and S/D ratio, pulsatility index for veins (PIV), as well as peak velocity index for veins (PVIV), were calculated. Regression analysis was used to determine reference ranges with gestation.

RESULTS

With advancing gestation, a significant increase in S, D and A velocities as well as in TVI, was observed. Whereas the S/D ratio remained constant, PVIV and PIV decreased significantly during the second half of pregnancy.

CONCLUSIONS

During the second half of pregnancy the increase in left atrial and ventricular compliance is reflected by the observed decrease in PIV and PVIV, which could be mainly due to the increased flow during atrial contraction. Such relative Doppler indices are better comparable than absolute values and are independent from the insonation angle. Potential clinical applications for such Doppler indices are conditions with possibly impaired left atrial function, like heart defects with left atrial obstruction or late stages of severe intrauterine growth retardation.

Radiofrequency-assisted atrial septoplasty for an intact atrial septum in complex congenital heart disease

Septoplasty of the atrial septum was performed with sequential balloon dilation following radiofrequency-assisted perforation of an intact atrial septum in two newborn infants with hypoplastic left heart syndrome and one with double-outlet right ventricle.

Fetal pulmonary venous flow pattern is determined by left atrial pressure: report of two cases of left heart hypoplasia, one with patent and the other with closed interatrial communication

We report two cases of fetal left heart hypoplasia with extremes of size of interatrial communication, i.e. a closed foramen ovale and an atrial septal defect. Doppler examinations of the pulmonary veins showed almost to and fro flow in the fetus with the closed foramen ovale and, in contrast, a normal flow velocity waveform in the fetus with the atrial septal defect, despite mitral atresia. Our observations support the importance of left atrial pressure in the creation of a pulmonary venous flow pattern in the fetus.

Improved surgical outcome after fetal diagnosis of hypoplastic left heart syndrome

BACKGROUND

Hypoplastic left heart syndrome (HLHS) is frequently diagnosed prenatally, but this has not been shown to improve surgical outcome.

METHODS AND RESULTS

We reviewed patients with HLHS between July 1992 and March 1999 to determine the influence of prenatal diagnosis on preoperative clinical status, outcomes of stage 1 surgery, and parental decisions regarding care. Of 88 patients, 33 were diagnosed prenatally and 55 after birth. Of 33 prenatally diagnosed patients, 22 were live-born, and pregnancy was terminated in 11. Of 22 prenatally diagnosed patients who were live-born, 14 underwent surgery, and parents elected to forego treatment in 8. Of 55 patients diagnosed postnatally, 38 underwent surgery, and 17 did not because of parental decisions or clinical considerations. Prenatally diagnosed patients were less likely to undergo surgery than patients diagnosed after birth (P:=0.008). Among live-born infants, there was a similar rate of nonintervention. Among patients who underwent surgery, survival was 75% (39/52). All patients who had a prenatal diagnosis and underwent surgery survived, whereas only 25 of 38 postnatally diagnosed patients survived (P:=0.009). Patients diagnosed prenatally had a lower incidence of preoperative acidosis (P:=0.02), tricuspid regurgitation (P:=0.001), and ventricular dysfunction (P:=0.004). They were also less likely to need preoperative inotropic medications or bicarbonate (P:=0.005). Preoperative factors correlating with early mortality included postnatal diagnosis (P:=0.009), more severe acidosis (P:=0.03), need for bicarbonate or inotropes (P:=0.008 and 0.04), and ventricular dysfunction (P:=0.05).

CONCLUSIONS

Prenatal diagnosis of HLHS was associated with improved preoperative clinical status and with improved survival after first-stage palliation in comparison with patients diagnosed after birth.

Fetal cardiology

The prevalence of congenital heart disease increases with increasing NT, and many defects can be detected by echocardiography performed by a specialist at 13 to 17 weeks. There is increasing evidence that a prenatal diagnosis improves fetal outcome. Physiology and pathophysiology of the human fetal pulmonary circulation play an important role in the fetal circulation, and recent studies about the reactivity of these vessels in the third trimester have contributed to increase our understanding. The main issue in fetal arrhythmias (brady- and tachycardia) is the correct indication, efficacy, and safety of treatment.

Prenatal therapy of non-immunologic hydrops fetalis caused by severe aortic stenosis

Congenital aortic stenosis is a rare cause of congestive heart failure and hydrops fetalis. This report describes a case of prenatally diagnosed critical aortic stenosis and endocardial fibroelastosis leading to a severe hydrops fetalis at 27 weeks of gestation. Successful transplacental digitalization was performed and all signs of hydrops resolved within 2 weeks. The pregnancy continued with normal development of the fetus and birth was induced at 39 weeks of gestation. After an uneventful vaginal birth, the child was transferred for cardiac catheterization, and balloon dilation of the aortic valve was performed successfully. Follow up at the age of 2 years showed only mild left ventricular cardiac hypertrophy, a moderate elevated pressure gradient of 50 mmHg at the aortic valve and mild aortic and mitral regurgitation. No further interventions were necessary at this point.