Prenatal intervention for the management of congenital diaphragmatic hernia

Exploring new perspectives on congenital diaphragmatic hernia: A comprehensive review

Congenital diaphragmatic hernia (CDH) represents a developmental anomaly that profoundly impacts the embryonic development of both the respiratory and cardiovascular systems. Understanding the influences of developmental defects, their origins, and clinical consequences is of paramount importance for further research and the advancement of therapeutic strategies for this condition. In recent years, groundbreaking studies in the fields of metabolomics and genomics have significantly expanded our knowledge regarding the pathogenic mechanisms of CDH. These investigations introduce novel diagnostic and therapeutic avenues. CDH implies a scarcity of available information within this domain. Consequently, a comprehensive literature review has been undertaken to synthesize existing data, providing invaluable insights into this rare disease. Improved comprehension of the molecular underpinnings of CDH has the potential to refine diagnostic precision and therapeutic interventions, thus potentially enhancing clinical outcomes for CDH patients. The identification of potential biomarkers assumes paramount significance for early disease detection and risk assessment in CDH, facilitating prompt recognition and the implementation of appropriate interventions. The process of translating research findings into clinical practice is significantly facilitated by an exhaustive literature review. It serves as a pivotal step, enabling the integration of novel, more effective diagnostic and therapeutic modalities into the management of CDH patients.

The etiology of congenital diaphragmatic hernia: the retinoid hypothesis 20 years later

Congenital diaphragmatic hernia (CDH) is a severe birth defect and a major cause of neonatal respiratory distress. Impacting ~2-3 in 10,000 births, CDH is associated with a high mortality rate, and long-term morbidity in survivors. Despite the significant impact of CDH, its etiology remains incompletely understood. In 2003, Greer et al. proposed the Retinoid Hypothesis, stating that the underlying cause of abnormal diaphragm development in CDH was related to altered retinoid signaling. In this review, we provide a comprehensive update to the Retinoid Hypothesis, discussing work published in support of this hypothesis from the past 20 years. This includes reviewing teratogenic and genetic models of CDH, lessons from the human genetics of CDH and epidemiological studies, as well as current gaps in the literature and important areas for future research. The Retinoid Hypothesis is one of the leading hypotheses to explain the etiology of CDH, as we continue to better understand the role of retinoid signaling in diaphragm development, we hope that this information can be used to improve CDH outcomes. IMPACT: This review provides a comprehensive update on the Retinoid Hypothesis, which links abnormal retinoic acid signaling to the etiology of congenital diaphragmatic hernia. The Retinoid Hypothesis was formulated in 2003. Twenty years later, we extensively review the literature in support of this hypothesis from both animal models and humans.

Rescuing lung development through embryonic inhibition of histone acetylation

A major barrier to the impact of genomic diagnosis in patients with congenital malformations is the lack of understanding regarding how sequence variants contribute to disease pathogenesis and whether this information could be used to generate patient-specific therapies. Congenital diaphragmatic hernia (CDH) is among the most common and severe of all structural malformations; however, its underlying mechanisms are unclear. We identified loss-of-function sequence variants in the epigenomic regulator gene SIN3A in two patients with complex CDH. Tissue-specific deletion of Sin3a in mice resulted in defects in diaphragm development, lung hypoplasia, and pulmonary hypertension, the cardinal features of CDH and major causes of CDH-associated mortality. Loss of SIN3A in the lung mesenchyme resulted in reduced cellular differentiation, impaired cell proliferation, and increased DNA damage. Treatment of embryonic Sin3a mutant mice with anacardic acid, an inhibitor of histone acetyltransferase, reduced DNA damage, increased cell proliferation and differentiation, improved lung and pulmonary vascular development, and reduced pulmonary hypertension. These findings demonstrate that restoring the balance of histone acetylation can improve lung development in the Sin3a mouse model of CDH.

Connecting clinical, environmental, and genetic factors point to an essential role for vitamin A signaling in the pathogenesis of congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a developmental disorder that results in incomplete diaphragm formation, pulmonary hypoplasia, and pulmonary hypertension. Although a variety of genes have been linked to its etiology, CDH is not a monogenetic disease, and the cause of the condition is still unclear in the vast majority of clinical cases. By comparing human clinical data and experimental rodent data from the literature, we present clear support demonstrating the importance of vitamin A (vitA) during the early window of pregnancy when the diaphragm and lung are forming. Alteration of vitA signaling via dietary and genetic perturbations can create diaphragmatic defects. Unfortunately, vitA deficiency is chronic among people of child-bearing age, and this early window of diaphragm development occurs before many might be aware of pregnancy. Furthermore, there is an increased demand for vitA during this critical period, which exacerbates the likelihood of deficiency. It would be beneficial for the field to further investigate the connections between maternal vitA and CDH incidence, with the goal of determining vitA status as a CDH risk factor. Regular clinical monitoring of vitA levels in child-bearing years is a tractable method by which CDH outcomes could be prevented or improved.

Simulation training for urgent postnatal fetal tracheal balloon removal: Two learning methods

OBJECTIVE

In fetuses with severe congenital diaphragmatic hernia, fetal endoluminal tracheal occlusion (FETO) with balloon increases survival and reduces morbidity. Balloon removal is often scheduled electively. In urgent cases, in-utero removal is impossible and removal immediately after delivery has to occur, posing risk of death from airway obstruction. Medical staff need training in urgent removal. Ideal training method is unclear; thus, we compared the performance of two groups trained by different methods.

METHODS

24 medical students were randomly assigned to two different learning methods for removal: Group 1 (in-person lecture) and Group 2 (online video). Both methods presented the same information: endoscopic instrument set-up, anatomical landmarks for intubation, and balloon removal. All participants were evaluated using the same instruments and high-fidelity simulator, comparing time for instrument set-up and simulate balloon removal (including removal attempts).

RESULTS

Group 1 took significantly less time for instrument set-up compared to Group 2 [62 (30-92) secs vs 81 (57-108) secs; p < 0.01)]; no difference in time to intubate and locate the balloon [75 (50-173) secs vs 92 (32-232) secs; p 0.42], or number of attempts.

CONCLUSION

There was no difference between video training and in-person training with regards to the time taken to locate the FETO balloon in the trachea and to simulate its removal.

Retinal findings in neonates with congenital diaphragmatic hernia and extracorporeal membrane oxygenation

PURPOSE

To evaluate the prevalence of retinal pathologies in neonates with congenital diaphragmatic hernia (CDH) receiving extracorporeal membrane oxygenation (ECMO) therapy.

METHODS

This retrospective study included consecutive infants that received ECMO therapy for CDH at our hospital between 2012 and 2018. Retinal changes were assessed by mydriatic indirect funduscopy. Recorded patient parameters include gestational age (GA), type of delivery, duration of ECMO therapy, duration of inhalative oxygen supplementation, and postmenstrual age at fundus examination.

RESULTS

Of 54 infants that were treated by ECMO therapy for CDH during the study period, 27 were medically stable enough to receive funduscopic examination and were thus included in the study. Mean GA of these 27 children was 37.3 weeks (range 33.1-40.6) and mean duration of inhalative oxygen supplementation was 12.8 weeks (range 2.7-56.4). Retinal changes were observed in 3 neonates (11.1%). These included multiple midperipheral blot intraretinal hemorrhages in 5 eyes of 3 children and retinopathy of prematurity (ROP) in 2 eyes (stage 3 and stage 2, respectively, without plus disease) of 1 child (GA 35.0 weeks; duration of inhalative oxygen supplementation, 11.9 weeks). In all infants, retinal changes regressed without therapeutic intervention.

CONCLUSIONS

Neonates treated with ECMO due to CDH may exhibit retinal hemorrhages, however usually without need for intervention. Prematurely born infants receiving ECMO may develop ROP and thus require ROP screening examinations.

TYPE OF STUDY

Prognosis study.

LEVEL OF EVIDENCE

Level III.

Fetal echocardiography (ECHO) in assessment of structural heart defects in congenital diaphragmatic hernia patients: Is early postnatal ECHO necessary for ECMO candidacy?

PURPOSE

The purpose of this study was to determine the accuracy of fetal echocardiogram (ECHO) for detecting cardiac structural anomalies that may impact Extracorporeal Membrane Oxygenation (ECMO) candidacy in infants with Congenital Diaphragmatic Hernia (CDH).

METHODS

A retrospective review was performed on fetuses with CDH (January 2007-June 2017). Inclusion criteria were inborn and at least one prenatal and postnatal ECHO. ECHOs were evaluated for structural heart defects. Primary outcomes were accuracy of prenatal fetal ECHO and identify differences between prenatal and postnatal ECHO. Descriptive statistics and Chi-square analysis were performed.

RESULTS

131 inborn patients were identified. Mean gestational age of fetal ECHO was 26.6 ± 5.5 weeks. The median time to postnatal ECHO was DOL 1 [0-30]. Fetal ECHO had 92% accuracy, 83% sensitivity, 93% specificity, PPV of 95%, NPV of 92%, and a 90% accuracy for visualization of at least one pulmonary vein into the left atrium on the contralateral (non-CDH) side. Thirty-five percent of patients received ECMO, and 26% had an associated cardiac anomaly. All ECMO patients had an accurate structural fetal ECHO.

CONCLUSION

Fetal ECHO is sufficient for identifying major structural heart defects at large volume centers with trained pediatric cardiologists and may be used to guide clinical management, particularly in regards to ECMO candidacy.

LEVEL OF EVIDENCE

Level III.