Perinatal profile of ventricular overload markers in congenital diaphragmatic hernia

Abnormal Shape and Size of the Cardiac Ventricles Are Associated with a Higher Risk of Neonatal Death in Fetuses with Isolated Left Congenital Diaphragmatic Hernia

INTRODUCTION

The objective of this study was to evaluate the association between fetal cardiac deformation analysis (CDA) and cardiac function with severe adverse perinatal outcomes in fetuses with isolated left congenital diaphragmatic hernia (CDH).

METHODS

CDA in each ventricle (contractility, size, and shape), evaluated by speckle tracking and novel FetalHQ software, and markers of cardiac function (E/A ratios, pulmonary and aortic peak systolic velocities, and sigmoid annular valve diameters), were evaluated in fetuses with isolated left CDH. Two evaluations were performed: at referral (CDA and function) and within 3 weeks of delivery (CDA). Severe adverse neonatal outcomes were considered neonatal death (ND) or survival with CDH-associated pulmonary hypertension (CDH-PH). Differences and associations between CDA, cardiac function, and severe adverse outcomes were estimated.

RESULTS

Fifty fetuses were included, and seventeen (34%) had severe adverse neonatal outcomes (11 ND and 6 survivors with CDH-PH). At first evaluation, the prevalence of a small left ventricle was 34% (17/50) with a higher prevalence among neonates presenting severe adverse outcomes (58.8 [10/17] vs. 21.2% [7/33]; p = 0.01; OR, 5.03 [1.4-19.1; p = 0.01]) and among those presenting with neonatal mortality (8/11 [72.7] vs. 9/39 [23.0%]; p = 0.03; OR, 8.9 [1.9-40.7; p = 0.005]). No differences in cardiac function or strain were noted between fetuses with or without severe adverse outcomes. Within 3 weeks of delivery, the prevalence of small left ventricle was higher (19/34; 55.8%) with a more globular shape (reduced transverse/longitudinal ratio). A globular right ventricle was significantly associated with ND or survival with CDH-PH (OR, 14.2 [1.5-138.3]; p = 0.02).

CONCLUSION

Fetuses with isolated CDH at risk of perinatal death or survival with CDH-PH had a higher prevalence of a small left ventricle and abnormal shape of the right ventricle.

Beyond the diaphragm and the lung: a multisystem approach to understanding congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a birth defect characterized by the incomplete closure of the diaphragm and herniation of abdominal organs into the chest during gestation. This invariably leads to an impairment in fetal lung development (pulmonary hypoplasia) that involves the pulmonary vessels (vascular remodeling) leading to postnatal pulmonary hypertension. Moreover, approximately 60% of CDH survivors have long-term comorbidities, including critical cardiac anomalies, neurodevelopmental impairment, gastroesophageal reflux, and musculoskeletal malformations. While the pathophysiology of the diaphragmatic defect and pulmonary hypoplasia have been studied in detail over the decades, less is known about the other organs affected in CDH. In this review, we searched the literature for reports on other organs beyond the lung and diaphragm in human and experimental models of CDH. We found studies reporting gross morphometric changes and alterations to biological pathways in the heart, brain, liver, kidney, gastrointestinal tract, and musculoskeletal system. Given the paucity of literature and the importance that these comorbidities play in the life of patients with CDH, further studies are needed to comprehensively uncover the pathophysiology of the changes observed in these other organs.

Extracellular matrix and cyclic stretch alter fetal cardiomyocyte proliferation and maturation in a rodent model of heart hypoplasia

Introduction

Birth defects, particularly those that affect development of the heart, are a leading cause of morbidity and mortality in infants and young children. Babies born with heart hypoplasia (heart hypoplasia) disorders often have a poor prognosis. It remains unclear whether cardiomyocytes from hypoplastic hearts retain the potential to recover growth, although this knowledge would be beneficial for developing therapies for heart hypoplasia disorders. The objective of this study was to determine the proliferation and maturation potential of cardiomyocytes from hypoplastic hearts and whether these behaviors are influenced by biochemical signaling from the extracellular matrix (ECM) and cyclic mechanical stretch.

Method

Congenital diaphragmatic hernia (CDH)-associated heart hypoplasia was induced in rat fetuses by maternal exposure to nitrofen. Hearts were isolated from embryonic day 21 nitrofen-treated fetuses positive for CDH (CDH+) and from fetuses without nitrofen administration during gestation.

Results and discussion

CDH+ hearts were smaller and had decreased myocardial proliferation, along with evidence of decreased maturity compared to healthy hearts. In culture, CDH+ cardiomyocytes remained immature and demonstrated increased proliferative capacity compared to their healthy counterparts. Culture on ECM derived from CDH+ hearts led to a significant reduction in proliferation for both CDH+ and healthy cardiomyocytes. Healthy cardiomyocytes were dosed with exogenous nitrofen to examine whether nitrofen may have an aberrant effect on the proliferative ability of cardiomyocyte, yet no significant change in proliferation was observed. When subjected to stretch, CDH+ cardiomyocytes underwent lengthening of sarcomeres while healthy cardiomyocyte sarcomeres were unaffected. Taken together, our results suggest that alterations to environmental cues such as ECM and stretch may be important factors in the pathological progression of heart hypoplasia.

The heart in congenital diaphragmatic hernia: Knowns, unknowns, and future priorities

There is growing recognition that the heart is a key contributor to the pathophysiology of congenital diaphragmatic hernia (CDH), in conjunction with developmental abnormalities of the lung and pulmonary vasculature. Investigations to date have demonstrated altered fetal cardiac morphology, notably relative hypoplasia of the fetal left heart, as well as early postnatal right and left ventricular dysfunction which appears to be independently associated with adverse outcomes. However, many more unknowns remain, not least an understanding of the genetic and cellular basis for cardiac dysplasia and dysfunction in CDH, the relationship between fetal, postnatal and long-term cardiac function, and the impact on other parts of the body especially the developing brain. Consensus on how to measure and classify cardiac function and pulmonary hypertension in CDH is also required, potentially using both non-invasive imaging and biomarkers. This may allow routine assessment of the relative contribution of cardiac dysfunction to individual patient pathophysiological phenotype and enable better, individualized therapeutic strategies incorporating targeted use of fetal therapies, cardiac pharmacotherapies, and extra-corporeal membrane oxygenation (ECMO). Collaborative, multi-model approaches are now required to explore these unknowns and fully appreciate the role of the heart in CDH.

Antenatal BAY 41-2272 reduces pulmonary hypertension in the rabbit model of congenital diaphragmatic hernia

Infants with congenital diaphragmatic hernia (CDH) fail to adapt at birth because of persistent pulmonary hypertension (PH), a condition characterized by excessive muscularization and abnormal vasoreactivity of pulmonary vessels. Activation of soluble guanylate cyclase by BAY 41-2272 prevents pulmonary vascular remodeling in neonatal rats with hypoxia-induced PH. By analogy, we hypothesized that prenatal administration of BAY 41-2272 would improve features of PH in the rabbit CDH model. Rabbit fetuses with surgically induced CDH at day 23 of gestation were randomized at day 28 for an intratracheal injection of BAY 41-2272 or vehicle. After term delivery (day 31), lung mechanics, right ventricular pressure, and serum NH2-terminal-pro-brain natriuretic peptide (NT-proBNP) levels were measured. After euthanasia, lungs were processed for biological or histological analyses. Compared with untouched fetuses, the surgical creation of CDH reduced the lung-to-body weight ratio, increased mean terminal bronchial density, and impaired lung mechanics. Typical characteristics of PH were found in the hypoplastic lungs, including increased right ventricular pressure, higher serum NT-proBNP levels, thickened adventitial and medial layers of pulmonary arteries, reduced capillary density, and lower levels of endothelial nitric oxide synthase. A single antenatal instillation of BAY 41-2272 reduced mean right ventricular pressure and medial thickness of small resistive arteries in CDH fetuses. Capillary density, endothelial cell proliferation, and transcripts of endothelial nitric oxide synthase increased, whereas airway morphometry, lung growth, and mechanics remained unchanged. These results suggest that pharmacological activation of soluble guanylate cyclase may provide a new approach to the prenatal treatment of PH associated with CDH.

Mid-term differences in right ventricular function in patients with congenital diaphragmatic hernia compared with controls

BACKGROUND

Patients with congenital diaphragmatic hernia (CDH) may have abnormal lung development, which may cause detrimental effects on right ventricular (RV) function. This study aimed to determine if there are persistent echocardiographic differences in RV function in patients with CDH years after repair versus control patients.

METHODS

Patients who underwent repair for CDH were recruited. RV function was evaluated by strain analysis and tissue Doppler imaging (TDI). Wilcoxon's rank-sum test was used for analysis.

RESULTS

Seven CDH patients and 16 control patients were studied. There was no difference in age between the CDH and control groups (6.2±1.7 years vs. 5.7±1.7 years). TDI demonstrated significantly lower values in the RV early diastolic wave (12.8±1.5 cm/s vs. 16.1±3.1 cm/s) and RV systolic wave (10.2± 0.8cm/s vs. 13.4±1.3 cm/s) when comparing the CDH group and the control group. Interventricular apical septal strain was signifi cantly lower in the CDH group than in the control group (-20.1±4.6% vs. -25.4±4.1%). There was a trend towards lower strain values in the RV mid-lateral segment in the CDH group (-30.8±9.9% versus -39.7±6.0%, P=0.06) and a lower global RV strain (-27.8±3.0% vs. -31.1±3.1%, P=0.06).

CONCLUSIONS

Patients who underwent CDH repair continue to have differences in RV function years after repair. Follow-up is needed to determine how these differences impact cardiac function in adult survivors of CDH.

Local fetal lung renin-angiotensin system as a target to treat congenital diaphragmatic hernia

Antenatal stimulation of lung growth is a reasonable approach to treat congenital diaphragmatic hernia (CDH), a disease characterized by pulmonary hypoplasia and hypertension. Several evidences from the literature demonstrated a possible involvement of renin-angiotensin system (RAS) during fetal lung development. Thus, the expression pattern of renin, angiotensin-converting enzyme, angiotensinogen, type 1 (AT₁) and type 2 (AT₂) receptors of angiotensin II (ANGII) was assessed by immunohisto-chemistry throughout gestation, whereas the function of RAS in the fetal lung was evaluated using fetal rat lung explants. These were morphometrically analyzed and intracellular pathway alterations assessed by Western blot. In nitrofen-induced CDH model, pregnant rats were treated with saline or PD-123319. In pups, lung growth, protein/DNA ratio, radial saccular count, epithelial differentiation and lung maturation, vascular morphometry, right ventricular hypertrophy and overload molecular markers, gasometry and survival time were evaluated. Results demonstrated that all RAS components were constitutively expressed in the lung during gestation and that ANGII had a stimulatory effect on lung branching, mediated by AT₁ receptor, through p44/42 and Akt phosphorylation. This stimulatory effect on lung growth was mimicked by AT₂-antagonist (PD-123319) treatment. In vivo antenatal PD-123319 treatment increased lung growth, ameliorated indirect parameters of pulmonary hypertension, improved lung function and survival time in nonventilated CDH pups, without maternal or fetal deleterious effects. Therefore, this study demonstrated a local and physiologically active RAS during lung morphogenesis. Moreover, selective inhibition of AT₂ receptor is presented as a putative antenatal therapy for CDH.

Plasma B-type natriuretic peptides in children with cardiovascular diseases

Natriuretic peptides (NP) are released from the heart in response to pressure and volume overload. The biologic properties of NPs include counterregulation of the rennin-angiotensin-aldosterone pathway and a decrease in sympathetic tone resulting in diuresis, natriuresis, and vasodilation. Natriuretic peptides help to maintain fluid balance and blood pressure in a healthy physiologic range. The B-type natriuretic peptide (BNP) and its N-terminal precursor (NTpBNP) have become important diagnostic biomarkers of cardiovascular diseases (CVDs) in adults. Although many studies suggest that BNP also is a reliable test for diagnosing significant CVDs in children, data are lacking on whether additional use of BNP increases diagnostic accuracy and predicts prognosis. This comprehensive review describes the utility of BNP and NTpBNP for various CVDs of the neonatal and pediatric age groups. Because BNP is not a stand-alone test, it should not replace history, physical examination, or clinical judgment, but it has a clear value in adding details to the whole story for children, thus enabling the front-line physicians to make a diagnosis, especially in the acute care setting.

Congenital diaphragmatic hernia: review of the literature in reflection of unresolved dilemmas

BACKGROUND

Congenital diaphragmatic hernia (CDH) is a rare but clinically and scientifically challenging condition. The introduction of ultrasound has enabled early prenatal detection and consequently, hope of early therapeutic intervention.

AIM

We undertook the task to review the recent developments in understanding the pathology of CDH as well as the history and current management strategies to aid perinatologists in consultations with parents of CDH-affected foetuses.

STUDY DESIGN

A Medline search was undertaken of all reports and reviews published between 1980 and 2008 using MeSH search terms 'diaphragmatic hernia', 'congenital' and 'newborn'.

RESULTS

The true incidence of CDH is still difficult to estimate because of the high incidence of hidden mortality of CDH. Complete case ascertainment also poses difficulties in assessment of the impact of new therapeutic modalities on overall survival. Recent improvements in prenatal detection are a milestone in affording time for re-assessments and parental counselling. The true benefit of antenatal therapy is circumscribed and should be offered only in selected cases of isolated severe CDH as defined by existing guidelines. Postnatal intensive respiratory supportive therapy and innovative surgical techniques within specialized tertiary centres has had a major impact on survival of babies with CDH.

CONCLUSION

The high survival of 'selected cases' that are live births and benefit from optimal care will be difficult to improve by antenatal interventions. The multidisciplinary approach to basic research and randomized clinical trials will further define the best approach to the foetus and neonate with CDH.