Fetal echocardiographic predictors of biventricular circulation in hypoplastic left heart complex

OBJECTIVES

To determine which echocardiographic features of hypoplastic left heart complex (HLHC) in the fetal period are predictive of biventricular (BV) circulation and to evaluate the long-term outcome of patients with HLHC, including rates of mortality, reintervention and development of further cardiac disease.

METHODS

Echocardiograms of fetuses with HLHC obtained at 18-26 weeks and 27-36 weeks' gestation between 2004 and 2017 were included in the analysis. The primary outcome was successful BV circulation (Group 1). Group 2 included patients with single-ventricle palliation, death or transplant. Univariate analysis was performed on data obtained at 18-26 and 27-36 weeks and multivariate logistic regression was performed on data obtained at 27-36 weeks only.

RESULTS

Of the 51 included cases, 44 achieved successful BV circulation (Group 1) and seven did not (Group 2). Right-to-left/bidirectional foramen ovale (FO) flow and a higher mitral valve (MV) annulus Z-score were associated with successful BV circulation on both univariate and multivariate analysis. Bidirectional or left-to-right FO flow, left ventricular length (LVL) Z-score of < -2.4 and a MV Z-score of < -4.5 correctly predicted 80% of Group 2 cases. Late follow-up was available for 41 patients. There were two late deaths in Group 2. Thirteen patients in Group 1 required reintervention, 12 developed mitral stenosis and five developed isolated subaortic stenosis.

CONCLUSIONS

BV circulation is common in fetuses with HLHC. Higher MV annulus and LVL Z-scores and right to left direction of FO flow are important predictors of BV circulation. Long-term sequelae in those with BV circulation may include mitral and subaortic stenosis. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Innovative 2-Step Management Strategy Utilizing EXIT Procedure for a Fetus With Hypoplastic Left Heart Syndrome and Intact Atrial Septum

Hypoplastic left heart syndrome (HLHS) with intact atrial septum (HLHS-IAS) carries a high risk of mortality and affects about 6% of all patients with HLHS. Fetal interventions, postnatal transcatheter interventions, and postnatal surgical resection have all been used, but the mortality risk continues to be high in this subgroup of patients. We describe a novel, sequential approach to manage HLHS-IAS and progressive fetal hydrops. A 28-year-old, gravida 4 para 2 mother was referred to Mayo Clinic for fetal HLHS. Fetal echocardiography at 28 weeks of gestation demonstrated HLHS-IAS with progressive fetal hydrops. The atrial septum was thick and muscular with no interatrial communication. Ultrasound-guided fetal atrial septostomy was performed with successful creation of a small atrial communication. However, fetal echocardiogram at 33 weeks of gestation showed recurrence of a pleural effusion and restriction of the atrial septum. We proceeded with an Ex uteroIntrapartum Treatment (EXIT) delivery and open atrial septectomy. This was performed successfully, and the infant was stabilized in the intensive care unit. The infant required venoarterial extracorporeal membrane oxygenator support on day of life 1. The patient later developed hemorrhagic complications, leading to his demise on day of life 9. This is the first reported case of an EXIT procedure and open atrial septectomy performed without cardiopulmonary bypass for an open-heart operation and provides a promising alternative strategy for the management of HLHS-IAS in select cases.

Cerebrovascular response to maternal hyperoxygenation in fetuses with hypoplastic left heart syndrome depends on gestational age and baseline cerebrovascular resistance

OBJECTIVES

Compared with normal fetuses, fetuses with hypoplastic left heart syndrome (HLHS) have smaller brain volumes and are at higher risk of brain injury, possibly due to diminished cerebral blood flow and oxygen content. By increasing cerebral oxygen delivery, maternal hyperoxygenation (MH) might improve brain development and reduce the risk of brain injury in these fetuses. This study investigated whether gestational age and baseline cerebrovascular resistance affect the response to MH in fetuses with HLHS.

METHODS

The study population comprised 43 fetuses with HLHS or HLHS variant referred for fetal echocardiography between January 2004 and September 2008. Middle cerebral artery (MCA) pulsatility index (PI), a surrogate measure of cerebrovascular resistance, was assessed between 20 and 41 weeks' gestation at baseline in room air (RA) and after 10 min of MH. Z-scores of MCA-PI were generated. A mixed-effects model was used to determine whether change in MCA-PI depends upon gestational age and baseline MCA-PI.

RESULTS

In RA and following MH, MCA-PI demonstrated a curvilinear relationship with gestational age in fetuses with HLHS, peaking at around 28 weeks and then falling more steeply near term. MCA-PI Z-score declined in a linear manner, such that it was 1.4 SD below that in normal fetuses at 38 weeks. Increase in MCA-PI Z-score after MH was first seen at ≥ 28 weeks. A baseline MCA-PI Z-score ≤ -0.96 was predictive of an increase in cerebrovascular resistance in response to MH.

CONCLUSION

In fetuses with HLHS, MCA-PI first increases in response to MH at ≥ 28 weeks' gestation. A baseline MCA-PI Z-score ≤ -0.96 predicts an increase in cerebrovascular resistance in response to MH. These results may have implications for clinical trials utilizing MH as a neuroprotective agent. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Improved technical success, postnatal outcome and refined predictors of outcome for fetal aortic valvuloplasty

OBJECTIVES

Fetal aortic valvuloplasty (FAV) may prevent progression of mid-gestation aortic stenosis to hypoplastic left heart syndrome (HLHS). The aim of this study was to evaluate whether technical success and biventricular (Biv) outcome after FAV have changed from an earlier (2000-2008) to a more recent (2009-2015) era and identify pre-FAV predictors of Biv outcome.

METHODS

We evaluated procedural and postnatal outcomes in 123 fetuses that underwent FAV for evolving HLHS at Boston Children's Hospital between 2000 and 2015. The primary outcome measure was circulation type (Biv vs single ventricle) at the time of neonatal hospital discharge. Classification and regression tree (CART) analysis was performed to construct a stratification algorithm to predict Biv circulation based on pre-FAV fetal variables.

RESULTS

The FAV procedure was technically successful in 101/123 (82%) fetuses, with a higher technical success rate in the more recent era than in the earlier one (49/52 (94%) vs 52/71 (73%); P = 0.003). In liveborn patients, the incidence of Biv outcome was higher in the recent than in the earlier era, both in the entire liveborn cohort (29/49 (59%) vs 16/62 (26%); P = 0.001) and in those in whom the procedure was technically successful (27/46 (59%) vs 15/47 (32%); P = 0.007). Independent predictors of Biv outcome were higher left ventricular (LV) pressure, larger ascending aorta, better LV diastolic function and higher LV long-axis Z-score. On CART analysis, fetuses with LV pressure > 47 mmHg and ascending aorta Z-score ≥ 0.57 had a 92% probability of Biv outcome (n = 24). Those with a lower LV pressure, or mitral dimension Z-score < 0.1 and mitral valve inflow time Z-score < -2 (n = 34) were unlikely to have Biv (probability of 9%). The remainder of the patients had an intermediate (∼40-60%) likelihood of Biv circulation.

CONCLUSIONS

The proportion of patients achieving Biv outcome after FAV has increased, probably owing to an improved technical success rate and modified selection criteria. Fetal factors, including LV pressure, size of the ascending aorta and diastolic function, are associated with likelihood of Biv circulation after FAV. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Fetal hemodynamic response to aortic valvuloplasty and postnatal outcome: a European multicenter study

OBJECTIVE

Fetal aortic stenosis may progress to hypoplastic left heart syndrome. Fetal valvuloplasty (FV) has been proposed to improve left heart hemodynamics and maintain biventricular (BV) circulation. The aim of this study was to assess FV efficacy by comparing survival and postnatal circulation between fetuses that underwent FV and those that did not.

METHODS

This was a retrospective multicenter study of fetuses with aortic stenosis that underwent FV between 2005 and 2012, compared with contemporaneously enrolled natural history (NH) cases sharing similar characteristics at presentation but not undergoing FV. Main outcome measures were overall survival, BV-circulation survival and survival after birth. Secondary outcomes were hemodynamic change and left heart growth. A propensity score model was created including 54/67 FV and 60/147 NH fetuses. Analyses were performed using logistic, Cox or linear regression models with inverse probability of treatment weighting (IPTW) restricted to fetuses with a propensity score of 0.14-0.9, to create a final cohort for analysis of 42 FV and 29 NH cases.

RESULTS

FV was technically successful in 59/67 fetuses at a median age of 26 (21-34) weeks. There were 7/72 (10%) procedure-related losses, and 22/53 (42%) FV babies were delivered at < 37 weeks. IPTW demonstrated improved survival of liveborn infants following FV (hazard ratio, 0.38; 95% CI, 0.23-0.64; P = 0.0001), after adjusting for circulation and postnatal surgical center. Similar proportions had BV circulation (36% for the FV cohort and 38% for the NH cohort) and survival was similar between final circulations. Successful FV cases showed improved hemodynamic response and less deterioration of left heart growth compared with NH cases (P ≤ 0.01).

CONCLUSIONS

We report improvements in fetal hemodynamics and preservation of left heart growth following successful FV compared with NH. While the proportion of those achieving a BV circulation outcome was similar in both cohorts, FV survivors showed improved survival independent of final circulation to 10 years' follow-up. However, FV is associated with a 10% procedure-related loss and increased prematurity compared with the NH cohort, and therefore the risk-to-benefit ratio remains uncertain. We recommend a carefully designed trial incorporating appropriate and integrated fetal and postnatal management strategies to account for center-specific practices, so that the benefits achieved by fetal therapy vs surgical strategy can be demonstrated clearly. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

The neurodevelopmental implications of hypoplastic left heart syndrome in the fetus

As survival after cardiac surgery continues to improve, an increasing number of patients with hypoplastic left heart syndrome are reaching school age and beyond, with growing recognition of the wide range of neurodevelopmental challenges many survivors face. Improvements in fetal detection rates, coupled with advances in fetal ultrasound and MRI imaging, are contributing to a growing body of evidence that abnormal brain architecture is in fact present before birth in hypoplastic left heart syndrome patients, rather than being solely attributable to postnatal factors. We present an overview of the contemporary data on neurodevelopmental outcomes in hypoplastic left heart syndrome, focussing on imaging techniques that are providing greater insight into the nature of disruptions to the fetal circulation, alterations in cerebral blood flow and substrate delivery, disordered brain development, and an increased potential for neurological injury. These susceptibilities are present before any intervention, and are almost certainly substantial contributors to adverse neurodevelopmental outcomes in later childhood. The task now is to determine which subgroups of patients with hypoplastic left heart syndrome are at particular risk of poor neurodevelopmental outcomes and how that risk might be modified. This will allow for more comprehensive counselling for carers, better-informed decision making before birth, and earlier, more tailored provision of neuroprotective strategies and developmental support in the postnatal period.

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.

Hypoplastic left heart syndrome and the nutmeg lung pattern in utero: a cause and effect relationship or prognostic indicator?

BACKGROUND

Hypoplastic left heart syndrome (HLHS) is the third most common cause of critical congenital heart disease in newborns, and one of the most challenging forms to treat. Secondary pulmonary lymphangiectasia has been recognized in association with HLHS, an appearance described on fetal MRI as the "nutmeg lung."

OBJECTIVE

To investigate the association of fetal nutmeg lung with HLHS survival.

MATERIALS AND METHODS

A retrospective search of the fetal MRI database was performed. The nutmeg lung pattern was defined as T2 heterogeneous signal with tubular structures radiating peripherally from the hila. Postnatal echocardiograms and charts were reviewed.

RESULTS

Forty-four fetal MR studies met inclusion criteria, of which 4 patients (9%) had the nutmeg lung pattern and 3 of whom also had restrictive lesions. Mortality in this nutmeg lung group was 100% by 5 months of age. Of the 40 patients without nutmeg lung, mortality/orthotopic heart transplant (OHT) was 35%. Of these 40 patients without nutmeg lung, 5 had restriction on echo, 3 of whom died/had OHT before 5 months of age (60% of patients with restriction and non-nutmeg lung). There was a significantly higher incidence of restrictive lesions (P = 0.02) and mortality/OHT (P = 0.02) in patients with nutmeg lung compared to those without.

CONCLUSION

The nutmeg lung MR appearance in HLHS fetuses is associated with increased mortality/OHT (100% in the first 5 months of life compared to 35% with HLHS alone). Not all patients with restrictive lesions develop nutmeg lung, and outcome is not as poor when restriction is present in isolation. Dedicated evaluation for nutmeg lung pattern on fetal MR studies may be useful to guide prognostication and aid clinicians in counseling parents of fetuses with HLHS.

Severe left diaphragmatic hernia limits size of fetal left heart more than does right diaphragmatic hernia

OBJECTIVES

To assess whether severity of congenital diaphragmatic hernia (CDH) correlates with the degree of left heart hypoplasia and left ventricle (LV) output, and to determine if factors leading to abnormal fetal hemodynamics, such as compression and reduced LV preload, contribute to left heart hypoplasia.

METHODS

This was a retrospective cross-sectional study of fetuses at 16-37 weeks' gestation that were diagnosed with CDH between 2000 and 2010. Lung-to-head ratio (LHR), liver position and side of the hernia were determined from stored ultrasound images. CDH severity was dichotomized based on LHR and liver position. The dimensions of mitral (MV) and aortic (AV) valves and LV were measured, and right and left ventricular outputs were recorded.

RESULTS

In total, 188 fetuses with CDH were included in the study, 171 with left CDH and 17 with right CDH. Fetuses with severe left CDH had a smaller MV (Z = -2.24 ± 1.3 vs -1.33 ± 1.08), AV (Z = -1.39 ± 1.21 vs -0.51 ± 1.05) and LV volume (Z = -4.23 ± -2.71 vs -2.08 ± 3.15) and had lower LV output (26 ± 10% vs 32 ± 10%) than those with mild CDH. MV and AV in fetuses with right CDH (MV, Z = -0.83 ± 1.19 and AV, Z = -0.71 ± 1.07) were larger than those in fetuses with left CDH, but LV outputs were similarly diminished, regardless of hernia side. Severe dextroposition and abnormal liver position were associated independently with smaller left heart, while LHR was not.

CONCLUSION

The severity of left heart hypoplasia correlates with the severity of CDH. Altered fetal hemodynamics, leading to decreased LV output, occurs in both right- and left-sided CDH, but the additional compressive effect on the left heart is seen only when the hernia is left-sided. Improved knowledge of the physiology of this disease may lead to advances in therapy and better risk assessment for use in counseling affected families.

Left atrial ligation alters intracardiac flow patterns and the biomechanical landscape in the chick embryo

BACKGROUND

Hypoplastic left heart syndrome (HLHS) is a major human congenital heart defect that results in single ventricle physiology and high mortality. Clinical data indicate that intracardiac blood flow patterns during cardiac morphogenesis are a significant etiology. We used the left atrial ligation (LAL) model in the chick embryo to test the hypothesis that LAL immediately alters intracardiac flow streams and the biomechanical environment, preceding morphologic and structural defects observed in HLHS.

RESULTS

Using fluorescent dye injections, we found that intracardiac flow patterns from the right common cardinal vein, right vitelline vein, and left vitelline vein were altered immediately following LAL. Furthermore, we quantified a significant ventral shift of the right common cardinal and right vitelline vein flow streams. We developed an in silico model of LAL, which revealed that wall shear stress was reduced at the left atrioventricular canal and left side of the common ventricle.

CONCLUSIONS

Our results demonstrate that intracardiac flow patterns change immediately following LAL, supporting the role of hemodynamics in the progression of HLHS. Sites of reduced WSS revealed by computational modeling are commonly affected in HLHS, suggesting that changes in the biomechanical environment may lead to abnormal growth and remodeling of left heart structures.

Fetal aortic valvuloplasty: investigating institutional bias in surgical decision-making

OBJECTIVES

Fetal aortic valvuloplasty may prevent the progression of aortic stenosis to hypoplastic left heart syndrome and allow biventricular rather than univentricular postnatal treatment. This study aimed to investigate whether blinded simulation of a multidisciplinary team approach aids interpretation of multicenter data to uncover institutional bias in postnatal decision-making following fetal cardiac intervention for aortic stenosis.

METHODS

The study included 109 cases of prenatally diagnosed aortic stenosis from 13 European countries, of which 32 had undergone fetal cardiac intervention. The multidisciplinary team, blinded to fetal cardiac intervention, institutional location and postnatal treatment, retrospectively assigned a surgical pathway (biventricular or univentricular) based on a review of recorded postnatal imaging and clinical characteristics. The team's decisions were the numerical consensus of silent voting, with case review when a decision was split. Funnel plots showing concordance between the multidisciplinary team and the local team's surgical choice (first pathway) and with outcome (final pathway) were created.

RESULTS

In 105 cases the multidisciplinary team reached a consensus decision regarding the surgical pathway, with no decision in four cases because the available imaging records were inadequate. Blinded multidisciplinary team consensus for the first pathway matched the decision of the surgical center in 93/105 (89%) cases, with no difference in agreement between those that had undergone successful fetal cardiac intervention (n = 32) and no (n = 74) or unsuccessful (n = 3) valvuloplasty (no fetal cardiac intervention) (κ = 0.73 (95% CI, 0.38-1.00) vs 0.74 (95% CI, 0.51-0.96)). However, funnel plots comparing multidisciplinary team individual decisions with those of the local teams displayed more discordance (meaning biventricular-univentricular conversion) for the final surgical pathway following fetal cardiac intervention than they did for cases without such intervention (36/74 vs 34/130; P = 0.002), and identified one outlying center.

CONCLUSIONS

The use of a blinded multidisciplinary team to simulate decision-making and presentation of data in funnel plots may assist in the interpretation of data submitted to multicenter studies and permit the identification of outliers for further investigation. In the case of aortic stenosis, a high level of agreement was observed between the multidisciplinary team and the surgical centers, but one outlying center was identified.

Hypoplastic left heart syndrome with restrictive atrial septum and advanced heart block documented with a novel fetal electrocardiographic monitor

Hypoplastic left ventricle with congenital heart block has been reported previously in a fetus with concurrent left atrial isomerism and levo-transposition of the great arteries. We present the unusual case of an infant diagnosed in utero with hypoplastic left heart syndrome, a restrictive atrial septum and advanced heart block but with D-looping of the ventricles and no atrial isomerism. In addition, fetal heart rhythm was documented with the assistance of a new fetal electrocardiographic monitor.

Assessment of left ventricular endocardial fibroelastosis in fetuses with aortic stenosis and evolving hypoplastic left heart syndrome

Systematic evaluation of left ventricular (LV) endocardial fibroelastosis (EFE) in the fetus has not been reported. The role of EFE in the pre- and postnatal evolution of hypoplastic left heart disease, and the implications of EFE for outcomes after prenatal intervention for fetal aortic stenosis with evolving hypoplastic left heart syndrome have also not been determined. A 4-point grading system (0-3) was devised for the assessment of fetal LV echogenicity, which was presumed to be due to EFE. Two reviewers independently graded EFE on the preintervention echocardiograms of fetuses treated with in utero aortic valvuloplasty for evolving hypoplastic left heart syndrome from 2000 to 2008. Intra- and interobserver reproducibility was determined for the EFE grade and characterization of related echocardiographic features. The relations among EFE severity, other left heart anatomic and physiologic variables, and postintervention outcomes were analyzed. The assessment and grading of EFE was possible for both observers in all 74 fetuses studied. By consensus, the EFE severity was grade 1 in 31 patients, grade 2 in 32, and grade 3 in 11. Fetuses with mild (grade 1) EFE had significantly greater maximum instantaneous aortic stenosis gradients (e.g., higher LV pressures) and less globular LV geometry than patients with grade 2 or 3 EFE on preintervention echocardiogram. The severity of EFE was not associated with the size of the aortic valve or LV. From preintervention to late gestation, the time-indexed change in LV end-diastolic volume was significantly greater in fetuses with grade 1 EFE than those with more severe EFE. Incorporation of EFE severity into our previously published threshold score improved the sensitivity and positive predictive value for the postnatal biventricular outcomes. In conclusion, echocardiographic grading of EFE is possible, with reasonable intra- and interobserver reliability in midgestation fetuses with evolving hypoplastic left heart syndrome. EFE severity corresponded to some indexes of left heart size, geometry, and function and with the probability of a biventricular outcome postnatally. Additional experience and external validation of the EFE grading scoring system are necessary.

[Recent developments in fetal surgery. Technical, organizational and ethical considerations]

Progress in prenatal diagnosis has led to more frequent detection of fetal abnormalities which, if left untreated, would be fatal or cause severe disabilities despite optimal postnatal care. Intrauterine surgery is possible in selected cases. Most procedures involve microendoscopy with local or regional analgesia. Fetal analgesia is indicated for procedures that are directly invasive for the fetus. Surgical treatment of twin-to-twin transfusion is so far the only example of successful fetal therapy, as demonstrated in a randomized controlled trial. The most severe forms of congenital diaphragmatic hernia may also benefit from temporary occlusion of the fetal trachea in order to allow lung growth and prevent pulmonary hypoplasia. The future of open fetal surgery will depend partly on the results of the ongoing MOM study of intrauterine coverage of myelomeningocele. These developments also raise ethical questions, including the competence of the surgical team, and the borderline between therapeutic innovation, experimental surgery, and standard of care. The possibility of therapeutic termination should not be overlooked.

Changes in left heart hemodynamics after technically successful in-utero aortic valvuloplasty

OBJECTIVE

Severe aortic stenosis in the mid-gestation fetus can progress to hypoplastic left heart syndrome (HLHS). @ In-utero aortic valvuloplasty is an innovative therapy to promote left ventricular growth and function and potentially to prevent HLHS. This study evaluated the effects of mid-gestation fetal balloon aortic valvuloplasty on subsequent fetal left ventricular function and left heart Doppler characteristics.

METHODS

We reviewed fetuses with aortic stenosis that underwent attempted in-utero aortic valvuloplasty between 2000 and 2006. Pre-intervention and the latest post-intervention fetal echocardiograms were analyzed to characterize changes in left heart function and Doppler characteristics in utero.

RESULTS

Forty-two fetuses underwent attempted aortic valvuloplasty during the study period, 12 of which were excluded from analysis secondary to inadequate follow-up data, termination or fetal demise. Study fetuses (n = 30) underwent pre-intervention echocardiography at a median gestational age of 23 weeks, and were followed for a median of 66 +/- 23 days post-intervention. In 26 fetuses, aortic valvuloplasty was technically successful. Among these 26, left heart physiology was abnormal pre-intervention and improved or normalized after intervention in most cases: biphasic mitral inflow was present in 5/25 (20%) cases pre-intervention and in 21/23 (91%) post-intervention (P < 0.001); moderate or severe mitral regurgitation was present in 14/26 (54%) cases pre-intervention and in 5/23 (22%) post-intervention (P = 0.02); bidirectional flow across the patent foramen ovale was present in 0/26 cases pre-intervention and in 6/25 (24%) post-intervention (P = 0.01); antegrade flow in the transverse arch was present in 0/25 cases pre-intervention and in 17/26 (65%) post-intervention (P < 0.001). The left ventricular ejection fraction increased from 19 +/- 10% pre-intervention to 39 +/- 14% post-intervention (P < 0.001). These changes were not observed in control fetuses (n = 18).

CONCLUSION

Fetal aortic valvuloplasty, when technically successful, improves left ventricular systolic function and left heart Doppler characteristics.

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.

Fetal Aortic Valve Stenosis and the Evolution of Hypoplastic Left Heart Syndrome

Background— Fetal aortic valvuloplasty may prevent progression of aortic stenosis (AS) to hypoplastic left heart syndrome (HLHS). Predicting which fetuses with AS will develop HLHS is essential to optimize patient selection for fetal intervention. The aim of this study was to define echocardiographic features associated with progression of midgestation fetal AS to HLHS.

Methods and Results— Fetal echocardiograms were reviewed from 43 fetuses diagnosed with AS and normal left ventricular (LV) length at ≤30 weeks’ gestation. Of 23 live-born patients with available follow-up data, 17 had HLHS and 6 had a biventricular circulation. At the time of diagnosis, LV length, mitral valve, aortic valve, and ascending aortic diameter Z-scores did not differ between fetuses that ultimately developed HLHS and those that maintained a biventricular circulation postnatally. However, all of the fetuses that progressed to HLHS had retrograde flow in the transverse aortic arch (TAA), 88% had left-to-right flow across the foramen ovale, 91% had monophasic mitral inflow, and 94% had significant LV dysfunction. In contrast, all 6 fetuses with a biventricular circulation postnatally had antegrade flow in the TAA, biphasic mitral inflow, and normal LV function. With advancing gestation, growth arrest of left heart structures became evident in fetuses developing HLHS.

Conclusions— In midgestation fetuses with AS and normal LV length, reversed flow in the TAA and foramen ovale, monophasic mitral inflow, and LV dysfunction are predictive of progression to HLHS. These physiological features may help refine patient selection for fetal intervention to prevent the progression of AS to HLHS.

Successful selective termination at 17 weeks' gestation in monochorionic monoamniotic twin pregnancy affected by twin-twin transfusion syndrome and discordant for hypoplastic left heart syndrome

OBJECTIVES

To report a successful selective feticide in a complicated monochorionic monoamniotic (MCMA) pregnancy.

METHODS

A case of MCMA pregnancy with severe twin-twin transfusion syndrome and discordant for hypoplastic left heart syndrome was diagnosed at 16 weeks' gestation. A complete ultrasound and fetoscopic surveillance was performed, ruling out cord entanglement and, thus, precluding the necessity of transecting the cord.

RESULTS

The selective feticide was successfully performed by bipolar coagulation of the umbilical cord of the abnormal fetus under ultrasound guidance. The survivor twin developed normally during the rest of the pregnancy and was born at term. At 6 months of age, the infant was healthy.

CONCLUSION

Selective feticide in complicated monoamniotic pregnancies can be safely performed. Cord entanglement can be confidently excluded by both ultrasound and fetoscopy, thus making the systematic transection of the umbilical cord unnecessary.

Hypoplastic left heart syndrome with intact or highly restrictive atrial septum: outcome after neonatal transcatheter atrial septostomy

BACKGROUND

Hypoplastic left heart syndrome (HLHS) with intact or very restrictive atrial septum is a highly lethal combination. We review our 13-year institutional experience treating this high-risk subgroup of patients with emergent catheter therapy.

METHODS AND RESULTS

Infants with HLHS requiring catheter septostomy within the first 2 days of life were compared with a matched control group with adequate interatrial communication. Preoperative, early postoperative, and medium-term survival were evaluated. Earlier experience was compared with recent results to assess the effect of changes in catheterization and surgical and intensive care unit management strategies over the study period. From 1990 to 2002, 33 newborns with HLHS (11% of newborns with HLHS managed during this period) underwent urgent/semiurgent catheterization to create or enlarge an interatrial communication before surgical palliation. Preoperative and early postoperative mortality were high (48%) compared with control HLHS patients, regardless of prenatal diagnosis and despite successful catheter-based atrial septostomy with clinical stabilization. Mortality trended down during the later part of the study period. Those who survived the neonatal period had late survival, pulmonary artery pressure, and resistance similar to those of control subjects.

CONCLUSIONS

Neonatal mortality in the subgroup of HLHS patients with intact or highly restrictive atrial septum remains high despite successful urgent septostomy. Persistently poor outcomes for these patients have prompted efforts at our center to develop techniques for fetal intervention for this condition, in the hope that prenatal relief of left atrial and pulmonary venous hypertension may promote normal pulmonary vascular and parenchymal development and improve both short- and long-term outcomes.

Hypoplastic left heart syndrome: new developments and current controversies

Prior to 1980, the diagnosis of hypoplastic left heart syndrome (HLHS) was almost uniformly lethal. Over the past 25 years, the development of operative options, including staged surgical palliation and infant heart transplant, have resulted in major improvements in survival and quality-of-life outcomes. Throughout this period, the optimal treatment strategy for children with HLHS has continued to be controversial. Current advances include fetal diagnosis, medical management, catheter intervention and operative techniques, and hold great promise for further improvements. However, as new techniques continue to evolve, controversies will continue to arise. This article will explore the treatment strategies for children with HLHS and review current controversies surrounding this complex congenital cardiac disease.

Molecular mechanisms of ventricular hypoplasia

We have established the beginnings of a road map to understand how ventricular cells become specified, differentiate, and expand into a functional cardiac chamber (Fig. 5). The transcriptional networks described here provide clear evidence that disruption of pathways affecting ventricular growth could be the underlying etiology in a subset of children born with malformation of the right or left ventricle. As we learn details of the precise mechanisms through which the critical factors function, the challenge will lie in devising innovative methods to augment or modify the effects of gene mutations on ventricular development. Because most congenital heart disease likely occurs in a setting of heterozygous, predisposing mutations of one or more genes, modulation of activity of critical pathways in a preventive fashion may be useful in averting disease in genetically susceptible individuals.

Hemodynamics is a key epigenetic factor in development of the cardiac conduction system

The His-Purkinje system (HPS) is a network of conduction cells responsible for coordinating the contraction of the ventricles. Earlier studies using bipolar electrodes indicated that the functional maturation of the HPS in the chick embryo is marked by a topological shift in the sequence of activation of the ventricle. Namely, at around the completion of septation, an immature base-to-apex sequence of ventricular activation was reported to convert to the apex-to-base pattern characteristic of the mature heart. Previously, we have proposed that hemodynamics and/or mechanical conditioning may be key epigenetic factors in development of the HPS. We thus hypothesized that the timing of the topological shift marking maturation of the conduction system is sensitive to variation in hemodynamic load. Spatiotemporal patterns of ventricular activation (as revealed by high-speed imaging of fluorescent voltage-sensitive dye) were mapped in chick hearts over normal development, and following procedures previously characterized as causing increased (conotruncal banding, CTB) or reduced (left atrial ligation, LAL) hemodynamic loading of the embryonic heart. The results revealed that the timing of the shift to mature activation displays striking plasticity. CTB led to precocious emergence of mature HPS function relative to controls whereas LAL was associated with delayed conversion to apical initiation. The results from our study indicate a critical role for biophysical factors in differentiation of specialized cardiac tissues and provide the basis of a new model for studies of the molecular mechanisms involved in induction and patterning of the HPS in vivo.

Hypoplastic Left Heart Syndrome

Hypoplastic left heart syndrome (HLHS) is a complex combination of cardiac malformations that probably results from multiple developmental errors in the early stages of cardiogenesis and that, if left untreated, invariably proves fatal. A variety of chest radiographic findings are seen in patients with HLHS, including an enlarged cardiac silhouette (notably a prominent right atrium), pulmonary venous hypertension, an atrial septal defect, and valvular stenosis or atresia. The recent evolution of palliative surgical procedures (modified Norwood procedure, bidirectional cavopulmonary shunt, modified Fontan procedure, aortic valvuloplasty, heart transplantation) has increased the survival rate in children with HLHS. Echocardiography allows accurate assessment of the size and location of the ductus arteriosus, the hemodynamics of the aortic root, the patency and size of the foramen ovale or atrial septal defect, and the presence of a ventricular septal defect to help determine whether surgical intervention is appropriate and, if so, to facilitate planning. Pediatric radiologists now view radiologic images obtained in patients with HLHS before surgical intervention and at important intervals during treatment. Familiarity with the malformations that characterize HLHS and the surgical procedures used to enhance postnatal survival will help pediatric radiologists provide better care for patients with this relatively common pathologic condition.

Right and left ventricular wall deformation patterns in normal and left heart hypoplasia chick embryos

The vertebrate embryonic ventricle transforms from a smooth-walled single tube to trabeculated right ventricular (RV) and left ventricular (LV) chambers during cardiovascular morphogenesis. We hypothesized that ventricular contraction patterns change from globally isotropic to chamber-specific anisotropic patterns during normal morphogenesis and that these deformation patterns are influenced by experimentally altered mechanical load produced by chronic left atrial ligation (LAL). We measured epicardial RV and LV wall strains during normal development and left heart hypoplasia produced by LAL in Hamburger-Hamilton stage 21, 24, 27, and 31 chick embryos. Normal RV contracted isotropically until stage 24 and then contracted preferentially in the circumferential direction. Normal LV contracted isotropically at stage 21, preferentially in the longitudinal direction at stages 24 and 27, and then in the circumferential direction at stage 31. LAL altered both RV and LV strain patterns, accelerated the onset of preferential RV circumferential strain patterns, and abolished preferential LV longitudinal strain (P < 0.05 vs. normal). Mature patterns of anisotropic RV and LV deformation develop coincidentally with morphogenesis, and changes in these deformation patterns reflect altered cardiovascular function and/or morphogenesis.

Nuchal translucency and congenital heart defects: heart failure or not?

OBJECTIVE

To determine whether heart failure is the mechanism underlying the association between increased fetal nuchal translucency and congenital heart defects.

METHODS

Retrospective analysis of the types of congenital heart defect observed in fetuses with increased nuchal translucency and those with normal nuchal scans. Retrospective quantitative analysis of cardiac size and left ventricular ejection fraction in fetuses with ventricular septal defects or the hypoplastic left heart syndrome.

RESULTS

Eighty-three fetuses with congenital heart defects had undergone nuchal screening of which 51 had increased nuchal translucency and 32 had normal nuchal translucency. A wide variety of different congenital cardiac lesions with different hemodynamic effects were observed in fetuses with increased nuchal translucency and those with normal nuchal scans. Defects primarily characterized by left heart obstruction, right heart obstruction and septal defects occurred in both groups. All measurements of cardiothoracic ratio and left ventricular ejection fraction fell within the normal range and there was no significant difference between fetuses with increased nuchal translucency and those with normal nuchal scans.

CONCLUSIONS

No specific type of congenital heart lesion is associated with increased nuchal translucency. The contention that heart failure explains the association between congenital heart defects and increased nuchal translucency is not supported by this study.

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

OBJECTIVE

To determine whether restriction at the atrial septum in the newborn with hypoplastic left heart syndrome can be predicted accurately by examining the pattern of pulmonary venous flow in the fetus. A restrictive atrial septum can contribute to haemodynamic instability before surgery for this lesion and has been associated with an increased mortality.

DESIGN

Pulmonary venous pulsed Doppler tracings were compared between fetuses with hypoplastic left heart syndrome and controls. The size of the atrial septal defect on the postnatal echocardiogram was graded according to the degree of restriction. Pulsed Doppler tracings of pulmonary venous blood flow were obtained in 18 fetuses with left atrial outflow atresia and compared with 77 controls, adjusted for gestational age. Postnatal echocardiograms were available for analysis in 13 of 18 neonates.

SETTING

A tertiary referral centre for fetal cardiology and paediatric cardiac surgery.

RESULTS

Fetuses with hypoplastic left heart syndrome were different from controls in all pulmonary vein indices measured. As assessed from the postnatal echocardiogram, there were seven fetuses with a restrictive atrial septum. In these fetuses, the systolic flow velocity (p < 0.01), S/D ratio (p < 0.01), and peak reversal wave (p < 0.001) in the pulmonary vein tracing showed a good correlation with the degree of restriction.

CONCLUSIONS

The Doppler pattern of pulmonary venous flow in the fetus with hypoplastic left heart syndrome appears to be a reliable predictor of restriction of the atrial septum in the neonate. This may help in the immediate post-delivery management of these infants before surgery.

Fetal diaphragmatic hernia: echocardiography and clinical outcome

It is difficult to predict survival of fetuses diagnosed prenatally with congenital diaphragmatic hernia. Some studies suggest that left heart underdevelopment is associated with poor outcome, but fetal echocardiographic variables have not been conclusively proven to be good predictors of postnatal survival. The authors reviewed detailed fetal echocardiographic studies in twelve fetuses with congenital diaphragmatic hernia. Ten echocardiographic variables, including left and right ventricular width, left ventricular volume, and left ventricular mass, were examined from a four-chamber view, corrected for gestational age, and compared with normal data. The results of this study showed no significant differences between survivors and nonsurvivors in the ten variables analyzed. Although left heart dimensions and left ventricular volume in fetuses with congenital diaphragmatic hernia were below the expected normal range, these results did not predict postnatal outcome.

Patterns of prenatal growth among infants with cardiovascular malformations: possible fetal hemodynamic effects

This study characterized fetal growth differences among control infants (n= 276) and infants with d-transposition of the great arteries (TGA) (n = 69), tetralogy of Fallot (n = 66), hypoplastic left heart syndrome (n = 51), and coarctation of the aorta (n = 65), thus permitting assessment of competing theories about the relation between these cardiovascular malformations and fetal growth disturbance. Subjects were liveborn singletons without genetic or extra-cardiovascular structural abnormalities sampled from the Baltimore-Washington Infant Study. Multivariate analysis of covariance was performed: birth weight, birth length, newborn head circumference, and two nonlinear functions of these measures were regressed jointly on a diagnostic class variable and covariates. Differences in the vectors of dependent variable means across diagnostic groups were striking (p < 0.0001). Infants with TGA had normal birth weight, but lesser head volume relative to birth weight. Infants with tetralogy of Fallot were smaller in all measured dimensions, but they were shaped normally. Infants with hypoplastic left heart syndrome were smaller in all measured dimensions, and head volume was disproportionately small relative to birth weight. Infants with coarctation of the aorta had lower birth weight, shorter birth length, and greater head volume relative to birth weight. These findings suggest that fetal circulatory abnormalities may predict abnormal patterns of fetal growth.

Risk factors for hypoplastic left heart syndrome

A case-control study was performed in Finland to investigate the etiology of the lethal heart malformation, hypoplastic left heart syndrome (HLHS). The cases represented all verified HLHS (n = 34) in Finland during 1982-1983, and controls (n = 756) were randomly selected from all babies born during the same period. Both case and control mothers were interviewed by midwives approximately 3 mo after delivery. Maternal upper respiratory infection during the first trimester of pregnancy was a significant risk factor for HLHS (OR = 2.5, Cl95 = 1.2-5.4). Maternal exposures at work to factors such as disinfectants, pesticides, dyes, lacquers or paints, and anesthetic gases were rare and failed to indicate any risk for HLHS. Maternal use of deodorants or hairsprays during the first trimester of pregnancy was not a significant risk factor for HLHS (OR = 1.8, Cl95 = 0.9-3.6). The risk of HLHS was not associated with seasonal variation, maternal smoking, alcohol or coffee consumption, or use of acetosalicylic acid. Because the study material is limited in size, the power of this investigation is weak for testing the teratogenicity of specific chemicals on the risk of HLHS. Thus, conclusions from the negative findings of this study should be drawn very carefully.