Pulmonary artery structural changes in pulmonary hypertension complicating congenital diaphragmatic hernia

Patterns and Outcomes of Epoprostenol Use in Infants with Congenital Diaphragmatic Hernia Requiring Extracorporeal Life Support

OBJECTIVE

To describe our experience utilizing epoprostenol for pulmonary hypertension (PH) in infants with congenital diaphragmatic hernia (CDH) requiring extracorporeal life support (ECLS).

STUDY DESIGN

We retrospectively reviewed infants diagnosed with CDH who required ECLS at our institution from 2013-2023. Data collected included demographics, disease characteristics, medication administration patterns, and hospital outcomes. We first compared infants who received intravenous epoprostenol and those who did not. Among infants who received epoprostenol, we compared survivors and non-survivors. Chi-square/Fisher's exact and Mann-Whitney tests were used, with significance p<0.05.

RESULTS

Fifty-seven infants were included; 40 (70.2%) received epoprostenol. Infants receiving epoprostenol had lower observed/expected total fetal lung volume (O/E TFLV) on MRI (20 vs. 26.2%, p=0.042) as well as higher prenatal frequency of liver-up (90 vs 64.7%, p=0.023) and "severe" classification (67.5 vs 35.3%, p=0.007). Survival with and without epoprostenol was comparable (60% vs. 64%, p=0.23). Of those receiving epoprostenol, both survivors and non-survivors had similar prenatal indicators of disease severity. Most (80%) of hernia defects were classified as Type C/D and 68% were repaired <72 hours after ECLS cannulation. The median age at initiation of epoprostenol was day of life 6 (IQR: 4, 7) in survivors and 8 (IQR: 7, 16) in non-survivors (p=0.012). Survivors had shorter ECLS duration (11 vs 20 days, p=0.049). Of non-survivors, refractory PH was the cause of death for 13 infants (81%).

CONCLUSION

In infants with CDH requiring ECLS, addition of epoprostenol appears promising and earlier initiation may affect survival.

Hemodynamic management of congenital diaphragmatic hernia: the role of targeted neonatal echocardiography

Congenital diaphragmatic hernia (CDH) is a major congenital anomaly, resulting from the herniation of abdominal contents into the thoracic cavity, thereby impeding the proper development of the lungs and pulmonary vasculature. CDH severity correlates with a spectrum of pulmonary hypoplasia, pulmonary hypertension (PHT), and cardiac dysfunction, constituting the pathophysiological triad of this complex condition. The accurate diagnosis and effective management of PHT and cardiac dysfunction is pivotal to optimizing patient outcomes. Targeted neonatal echocardiography is instrumental in delivering real-time data crucial for the bespoke, pathophysiology-targeted hemodynamic management of CDH-associated PHT.

Endothelial-to-Mesenchymal Transition in Human and Murine Models of Congenital Diaphragmatic Hernia

INTRODUCTION

Congenital diaphragmatic hernia (CDH) is a complex congenital disorder, characterized by pulmonary hypertension (PH) and hypoplasia. PH secondary to CDH (CDH-PH) features devastating morbidity and mortality (25-30%) among neonates. An unmet need is determining mechanisms triggering CDH-PH to save infants. Prior data suggest abnormal remodeling of the pulmonary vascular extracellular matrix (ECM), presumed to be driven by endothelial-to-mesenchymal transition (EndoMT), hinders postnatal vasodilation and limits anti-PH therapy in CDH. There are limited data on the role of EndoMT in CDH-PH.

METHODS

The purpose of the study was to investigate how EndoMT contributes to CDH-PH by identifying cells undergoing EndoMT noted by alpha smooth muscle actin (α-SMA) expression in human umbilical vein endothelial cells (HUVECs) and lung tissue obtained from murine pups using the nitrofen model. N = 8 CDH, N = 8 control HUVECs were stained for α-SMA and CD31 after being exposed for 24 h to TGFB, a known EndoMT promoter. N = 8 nitrofen, N = 8 control murine pup lungs were also stained for α-SMA and CD31. α-SMA and CD31 expression was quantified in HUVECs and murine tissue using Fiji imaging software and normalized to the total number of cells per slide noted by DAPI staining.

RESULTS

CDH HUVECs demonstrated a 1.1-fold increase in α-SMA expression (p = 0.02). The murine model did not show statistical significance between nitrofen and control pup lungs; however, there was a 0.4-fold increase in α-SMA expression with a 0.8-fold decrease in CD31 expression in the nitrofen pup lungs when compared to controls.

CONCLUSION

These results suggest that EndoMT could potentially play a role in the ECM remodeling seen in CDH-PH.

Congenital Diaphragmatic Hernia: Pulmonary Hypertension and Pulmonary Vascular Disease

This review provides a comprehensive summary of the current understanding of pulmonary hypertension (PH) in congenital diaphragmatic hernia, outlining the underlying pathophysiologic mechanisms, methods for assessing PH severity, optimal management strategies, and prognostic implications.

Unique Cardiopulmonary Interactions in Congenital Diaphragmatic Hernia: Physiology and Therapeutic Implications

Congenital diaphragmatic hernia (CDH) results in abdominal contents entering the thoracic cavity, affecting both cardiac and pulmonary development. Maldevelopment of the pulmonary vasculature occurs within both the ipsilateral lung and the contralateral lung. The resultant bilateral pulmonary hypoplasia and associated pulmonary hypertension are important components of the pathophysiology of this disease that affect outcomes. Despite prenatal referral to specialized high-volume centers, advanced ventilation strategies, pulmonary hypertension management, and the option of extracorporeal membrane oxygenation, overall CDH mortality remains between 25% and 30%. With increasing recognition that cardiac dysfunction plays a large role in morbidity and mortality in patients with CDH, it becomes imperative to understand the different clinical phenotypes, thus allowing for individual patient-directed therapies. Further research into therapeutic interventions that address the cardiopulmonary interactions in patients with CDH may lead to improved morbidity and mortality outcomes.

Current and emerging pharmacotherapies for the treatment of pulmonary arterial hypertension in infants

INTRODUCTION

Pulmonary hypertension (PH) is a complex condition that encompasses an array of underlying disease processes and affects a diverse population of infants, including those with congenital heart disease, congenital diaphragmatic hernia, persistent PH of the newborn, and those with lung disease such as bronchopulmonary dysplasia. While there are treatments available to adults with PH, limited data exists for infants, especially for the newer medications. Therapies that target the three main pathophysiologic pathways of pulmonary hypertension appear to benefit infants, but which are best for each individual disease process is unclear.

AREAS COVERED

A review of the therapies to treat pulmonary hypertension is covered in this article including the prostacyclin pathway, endothelin pathway, and the nitric oxide pathway. Other adjunctive treatments are also discussed. Findings are based on a PubMed literature search of research papers spanning 1990-2023 and a search of ongoing trials registered with clinicaltrials.gov.

EXPERT OPINION

Overall therapies seem to improve outcomes with most infants with PH. However, given the diverse population of infants with PH, it is imperative to understand the basis for the PH in individual patients and understand which therapies can be applicable. Further research into tailored therapy for the specific populations is warranted.

Recent Advances in Pediatric Pulmonary Hypertension: Implications for Diagnosis and Treatment

PURPOSE

Pediatric pulmonary hypertension (PH) is a condition characterized by elevated pulmonary arterial pressure, which has the potential to be life-limiting. The etiology of pediatric PH varies. When compared with adult cohorts, the etiology is often multifactorial, with contributions from prenatal, genetic, and developmental factors. This review aims to provide an up-to-date overview of the causes and classification of pediatric PH, describe current therapeutics in pediatric PH, and discuss upcoming and necessary research in pediatric PH.

METHODS

PubMed was searched for articles relating to pediatric pulmonary hypertension, with a particular focus on articles published within the past 10 years. Literature was reviewed for pertinent areas related to this topic.

FINDINGS

The evaluation and approach to pediatric PH are unique when compared with that of adults, in large part because of the different, often multifactorial, causes of the disease in children. Collaborative registry studies have found that the most common disease causes include developmental lung disease and subsets of pulmonary arterial hypertension, which includes genetic variants and PH associated with congenital heart disease. Treatment with PH-targeted therapies in pediatrics is often guided by extrapolation of adult data, small clinical studies in pediatrics, and/or expert consensus opinion. We review diagnostic considerations and treatment in some of the more common pediatric subpopulations of patients with PH, including developmental lung diseases, congenital heart disease, and trisomy 21.

IMPLICATIONS

The care of pediatric patients with PH requires consideration of unique pediatric-specific factors. With significant variability in disease etiology, ongoing efforts are needed to optimize treatment strategies based on disease phenotype and guide evidence-based practices.

Pathological findings in congenital diaphragmatic hernia on necropsy studies: A single-center case series

INTRODUCTION

Congenital diaphragmatic hernia (CDH) is associated with high mortality rates and significant pulmonary morbidities. The objective of this study was to delineate the histopathological features observed in necropsies of CDH patients and correlate these with their clinical manifestations.

METHODS

We retrospectively reviewed the postmortem findings and corresponding clinical characteristics in eight CDH cases from 2017 to July 2022.

RESULTS

The median survival time was 46 (8-624) hours. Autopsy reports showed that diffuse alveolar damage (congestion and hemorrhage) and hyaline membrane formation were the primary pathological lung changes observed. Notably, despite significant reduction in lung volume, the lung development appeared normal in 50% of the cases, while lobulated deformities were present in three (37.5%) cases. All patients displayed a large patent ductus arteriosus (PDA) and a patent foramen ovale, resulting in increased right ventricle (RV) volume, and myocardial fibers appeared slightly congested and swollen. The pulmonary vessels indicated thickening of the arterial media and adventitia. Lung hypoplasia and diffuse lung damage resulted in impaired gas exchange, while PDA and pulmonary hypertension led to RV failure, subsequent organ dysfunction and ultimately death.

CONCLUSIONS

Patients with CDH typically succumb to cardiopulmonary failure, a condition driven by a complex interplay of pathophysiological factors. This complexity accounts for the unpredictable response to currently available vasodilators and ventilation therapies.

Diagnosis & management of pulmonary hypertension in congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) contributes to neonatal morbidity and mortality worldwide. Pulmonary hypertension (PH) is a key component of CDH pathophysiology and critical consideration for management and therapeutic options. PH associated with CDH has traditionally been attributed to pulmonary vascular maldevelopment and associated lung parenchymal hypoplasia, leading to pre-capillary increase in pulmonary vascular resistance (PVR). However, there is increasing recognition that left ventricular hypoplasia, dysfunction and elevated end diastolic pressure may contribute to post-capillary pulmonary hypertension in CDH patients. The interplay of these mechanisms and associated dysfunction in the right and left ventricles results in variable hemodynamic phenotypes in CDH. Clinical assessment of individual phenotype may help guide personalized management strategies, including effective use of pulmonary vasodilators and extra-corporeal membrane oxygenation. Ongoing investigation of the underlying mechanisms of PH in CDH, and efficacy of physiology-based treatment approaches may support improvement in outcomes in this challenging condition.

Congenital diaphragmatic hernia: a narrative review of controversies in neonatal management

The consequences of most hernias can be immediately corrected by surgical repair. However, this isn't always the case for children born with a congenital diaphragmatic hernia. The derangements in physiology encountered immediately after birth result from pulmonary hypoplasia and hypertension caused by herniation of abdominal contents into the chest early in lung development. This degree of physiologic compromise can vary from mild to severe. Postnatal management of these children remains controversial. Although heavily studied, multi-institutional randomized controlled trials are lacking to help determine what constitutes best practice. Additionally, the results of the many studies currently within the literature that have investigated differing aspect of care (i.e., inhaled nitric oxide, ventilator type, timing of repair, role of extracorporeal membrane oxygenation, etc.) are difficult to interpret due to the small numbers investigated, the varying degree of physiologic compromise, and the contrasting care that exists between institutions. The aim of this paper is to review areas of controversy in the care of these complex kids, mainly: the use of fraction of inspired oxygen, surfactant therapy, gentle ventilation, mode of ventilation, medical management of pulmonary hypertension (inhaled nitric oxide, sildenafil, milrinone, bosentan, prostaglandins), the utilization of extracorporeal membrane oxygenation, and the timing of surgical repair.

Congenital diaphragmatic hernia-associated cardiac dysfunction

There is increasing evidence that cardiac dysfunction is a key contributor to CDH pathophysiology. Dysfunction in both right and left ventricles is common in the early neonatal period, contributes to clinical disease severity, and is associated with adverse outcomes including death and ECMO use. Early and routine assessment of ventricular function and pulmonary artery pressure may guide individualized clinical decision-making, including use of pulmonary vasodilators, cardiotropes, ECMO, and timing of surgical repair. Minimizing cardiac dysfunction, whether by prenatal, postnatal or perinatal treatment strategies, may lead to improved outcome in CDH.

Vascular and ventilatory mechanical responses in three different stages of pulmonary development in the rabbit model of congenital diaphragmatic hernia 1

PURPOSE

To evaluate the vascular ventilatory response in different stages of lung development and to compare them to the neonates with congenital diaphragmatic hernia (CDH) in a rabbit model.

METHODS

New Zealand rabbits were divided into 8 groups (n=5): E25, E27, E30, and CDH. All groups were ventilated on a FlexiVent (Scireq, Montreal, QC, Canada), compounding the other 4 groups. The CDH surgery was performed at E25 and the harvest at E30. Dynamic compliance (CRS), dynamic elastance (ERS) and dynamic resistance (RRS) were measured every 4 min/24 min. Median wall thickness (MWT) and airspace were measured. ANOVA Bonferroni tests were used to perform statistical analysis. Significance was considered when p<0.05.

RESULTS

CRS was higher in E30 compared to all other groups (p<0.05). CRS and RRS of CDH and E27 were similar and were higher in E25 (p<0.05). MWT was decreased according to the gestational age, was increased in E27V and E30V (p<0.05) and decreased in CDHV (p<0.05), airspace was decreased in E25 and increased in all ventilated groups (p<0.05).

CONCLUSIONS

The ventilation response of congenital diaphragmatic hernia is like the pseudoglandular stage of the lung development. These findings add information about the physiology of pulmonary ventilation in CDH.

Ventricular Dysfunction, Interdependence, and Mechanical Dispersion in Newborn Infants with Congenital Diaphragmatic Hernia

BACKGROUND

Congenital diaphragmatic hernia (CDH) is an important cause of mortality and morbidity in the neonatal period. Pulmonary hypertension and pulmonary hypoplasia are key pathological findings. Cardiac function may also be an important determinant of disease severity, prognostic indicator, and therapeutic target in CDH.

OBJECTIVE

The aim of this study was to assess ventricular mechanics and synchrony in infants with CDH and controls using speckle tracking echocardiography (STE).

METHODS

Retrospective analysis was performed of echocardiograms obtained in the first 48 h of life in 27 infants with CDH and 20 controls. STE-derived longitudinal strain (LS) was measured in the right and left ventricles (RV, LV). Circumferential strain (CS) and radial strain (RS) were additionally measured in the LV. Mechanical dispersion (MD), a measure of synchrony, was assessed by calculation of the standard deviation of time to peak systolic strain in six ventricular segments.

RESULTS

RV LS and LV LS, LV CS, and LV RS were significantly reduced in CDH compared to controls. In the LV free wall, LS and RS were significantly reduced in CDH. LV LS correlated significantly with RV LS in CDH cases (r2 = 0.37, p = 0.002), but not controls (r2 = 0.19, p = 0.06). LV LS also correlated with LV MD in CDH (r2 = 0.25, p = 0.01) but not controls (r2 = 0.02, p = 0.54).

CONCLUSIONS

Global impairment of RV and LV systolic function are present in newborn infants with CDH and are associated with primary left ventricular dysfunction, ventricular interdependence, and MD.

Early Postnatal Ventricular Dysfunction Is Associated with Disease Severity in Patients with Congenital Diaphragmatic Hernia

OBJECTIVE

To assess patterns of postnatal ventricular function and their relationship to prenatal and postnatal markers of disease severity in infants with congenital diaphragmatic hernia (CDH).

STUDY DESIGN

In this observational case-control study of cardiac function in infants with CDH in the first 5 days of life, systolic and diastolic function in the right ventricle (RV) and left ventricle (LV) were assessed using speckle tracking echocardiography-derived global strain and tissue Doppler imaging. Correlation between cardiac function and prenatal observed:expected total fetal lung volume (TFLV), oxygenation index (OI), duration of intubation, and hospital length of stay were assessed.

RESULTS

All measures of systolic and diastolic function were significantly reduced in the CDH group (n = 25) compared with controls (n = 20) at <48 hours, and were improved by 72-120 hours. LV global systolic longitudinal strain (GLS) correlated with prenatal TFLV (R² = 0.32; P = .03), OI (R² = 0.35; P < .001), duration of intubation (R² = 0.24; P = .04), and length of stay (R² = 0.4; P = .006). Mean (SD) LV GLS at <48 hours was significantly lower in infants with CDH who did not survive and/or required ECMO compared with those who did not: -11.5 (5.3)% vs -16.9 (5.3)% (P = .02).

CONCLUSIONS

RV and LV function are impaired in the transitional period in infants with CDH. Early LV systolic function correlates with prenatal and postnatal markers of clinical disease severity and may be an important determinant of disease severity and therapeutic target in CDH. These findings support regular assessment of cardiac function in CDH and investigational trials of targeted cardiovascular therapies.

Anti-oxidants correct disturbance of redox enzymes in the hearts of rat fetuses with congenital diaphragmatic hernia

AIM

To evaluate if the redox system is unbalanced in the hearts of nitrofen-induced congenital diaphragmatic hernia  (CDH) animals and to study the possible preventive effects of two anti-oxidant treatments, apocynin and epigallocatechin-3-gallate (EGCG).

METHODS

Adult rats were divided into four groups. Group 1: rats received only vehicle on day E9.5. Group 2: rats received 100 mg nitrofen on day E9.5. Group 3: 1 month before mating rats received apocynin 1.5 mM and, when pregnant, 100 mg nitrofen on day E9.5. Group 4: same than group 3 but with EGCG 30 mg/kg. All fetuses were recovered at term and the hearts were processed. Nox activity and mRNA levels of Nox1, Nox2, Nox4, SOD1, SOD2, SOD3, catalase, and GPX1 were analyzed. Nox, SOD, and Catalase activity and H2O2 production were also evaluated.

RESULTS

Nox activity, H₂O₂ production and Nox1, Nox2, and Nox4 mRNA levels were increased in the hearts of fetuses with CDH. There were no changes in SOD1 levels, whereas those of SOD2, SOD3, catalase, and GPX1 mRNA were decreased. Apocynin and EGCG treatments attenuated the increment of Nox and SOD activities and H₂O₂ production was only decreased by apocynin.

CONCLUSION

These findings suggest a possible preventive effect on the abnormal redox metabolism of anti-oxidant treatments in the hearts from rat fetuses with CDH. If the same occurs in humans, it could represent a potential tool in future prenatal treatment.

Complications in neonatal surgery

Neonatal surgery is recognized as an independent discipline in general surgery, requiring the expertise of pediatric surgeons to optimize outcomes in infants with surgical conditions. Survival following neonatal surgery has improved dramatically in the past 60 years. Improvements in pediatric surgical outcomes are in part attributable to improved understanding of neonatal physiology, specialized pediatric anesthesia, neonatal critical care including sophisticated cardiopulmonary support, utilization of parenteral nutrition and adjustments in fluid management, refinement of surgical technique, and advances in surgical technology including minimally invasive options. Nevertheless, short and long-term complications following neonatal surgery continue to have profound and sometimes lasting effects on individual patients, families, and society.

Enhanced Pulmonary Vascular and Alveolar Development via Prenatal Administration of a Slow-Release Synthetic Prostacyclin Agonist in Rat Fetal Lung Hypoplasia

Lung hypoplasia and pulmonary hypertension are the major causes of mortality in neonates with congenital diaphragmatic hernia (CDH). Although the prostaglandin pathway plays a pivotal role in lung development, the reported efficacy of postnatal prostaglandin agonist treatment is suboptimal. We hypothesized that prenatal treatment with ONO-1301SR, a slow-release form of a novel synthetic prostacyclin agonist with thromboxane inhibitory activity, might enhance the development of lungs exhibiting hypoplasia in the fetal period. On embryonic day (E) 9.5, nitrofen was given to pregnant Sprague-Dawley rats to establish a CDH-related lung hypoplasia model, whereas normal rats received the vehicle only. The same day, either ONO-1301SR or a placebo was also randomly administered. On E21.5, the fetuses of the normal group and those exhibiting CDH were analyzed. Prenatal ONO-1301SR administration had no influence on the incidence of nitrofen-induced CDH. The lung-to-body weight ratio in the CDH+ONO group was greater than that in the CDH group. Histologically, the medial wall in the CDH+ONO group was two-thirds thinner than that in the CDH group. In addition, the number of Ttf-1-positive cells and the capillary density were ≥1.5 times greater in the CDH+ONO group than in the CDH group, and this increase was associated with higher expression of vascular endothelial growth factor and stromal cell-derived factor in the CDH+ONO group, suggesting enhanced development of the alveolar and capillary networks. Thus, prenatal ONO-1301SR was protective against the progression of lung hypoplasia associated with CDH in a nitrofen-induced rat model, indicating the potential of this treatment for pathologies exhibiting lung hypoplasia.

HIF2α-arginase axis is essential for the development of pulmonary hypertension

Hypoxic pulmonary vasoconstriction is correlated with pulmonary vascular remodeling. The hypoxia-inducible transcription factors (HIFs) HIF-1α and HIF-2α are known to contribute to the process of hypoxic pulmonary vascular remodeling; however, the specific role of pulmonary endothelial HIF expression in this process, and in the physiological process of vasoconstriction in response to hypoxia, remains unclear. Here we show that pulmonary endothelial HIF-2α is a critical regulator of hypoxia-induced pulmonary arterial hypertension. The rise in right ventricular systolic pressure (RVSP) normally observed following chronic hypoxic exposure was absent in mice with pulmonary endothelial HIF-2α deletion. The RVSP of mice lacking HIF-2α in pulmonary endothelium after exposure to hypoxia was not significantly different from normoxic WT mice and much lower than the RVSP values seen in WT littermate controls and mice with pulmonary endothelial deletion of HIF-1α exposed to hypoxia. Endothelial HIF-2α deletion also protected mice from hypoxia remodeling. Pulmonary endothelial deletion of arginase-1, a downstream target of HIF-2α, likewise attenuated many of the pathophysiological symptoms associated with hypoxic pulmonary hypertension. We propose a mechanism whereby chronic hypoxia enhances HIF-2α stability, which causes increased arginase expression and dysregulates normal vascular NO homeostasis. These data offer new insight into the role of pulmonary endothelial HIF-2α in regulating the pulmonary vascular response to hypoxia.

Increased c-kit and stem cell factor expression in the pulmonary vasculature of nitrofen-induced congenital diaphragmatic hernia

PURPOSE

Persistent pulmonary hypertension(PPH) in congenital diaphragmatic hernia (CDH) is caused by increased vascular cell proliferation and endothelial cell (EC) dysfunction, thus leading to obstructive changes in the pulmonary vasculature. C-Kit and its ligand, stem cell factor(SCF), are expressed by ECs in the developing lung mesenchyme, suggesting an important role during lung vascular formation. Conversely, absence of c-Kit expression has been demonstrated in ECs of dysplastic alveolar capillaries. We hypothesized that c-Kit and SCF expression is increased in the pulmonary vasculature of nitrofen-induced CDH.

METHODS

Timed-pregnant rats received nitrofen or vehicle on gestational day 9(D9). Fetuses were sacrificed on D15, D18, and D21, and divided into control and CDH group. Pulmonary gene expression levels of c-Kit and SCF were analyzed by qRT-PCR. Immunofluorescence double staining for c-Kit and SCF was combined with CD34 to evaluate protein expression in ECs of the pulmonary vasculature.

RESULTS

Relative mRNA levels of c-Kit and SCF were significantly increased in lungs of CDH fetuses on D15, D18, and D21 compared to controls. Confocal laser scanning microscopy confirmed markedly increased vascular c-Kit and SCF expression in mesenchymal ECs of CDH lungs on D15, D18, and D21 compared to controls.

CONCLUSION

Increased expression of c-Kit and SCF in the pulmonary vasculature of nitrofen-induced CDH lungs suggest that increased c-Kit signaling during lung vascular formation may contribute to vascular remodeling and thus to PPH.

An association between pulmonary hypertension and impaired lung function in infants with congenital diaphragmatic hernia

RATIONALE

Infants with congenital diaphragmatic hernia (CDH) can develop pulmonary hypertension (PH) from decreased number and abnormal muscularization of pulmonary arteries. Normally pulmonary vascular growth and remodeling parallel airspace growth and alveolarization, which exhibits a wide morphologic variation in CDH.

AIM

To assess whether infants with CDH and PH have greater abnormalities in infant pulmonary function testing (IPFT) compared to those without PH.

METHODS

We reviewed results of IPFTs and echocardiograms performed on infants with CDH from 2004 to June 2011. Lung volumes, forced flows and tidal mechanics were standardized according to available reference values. Comparisons between infants with and without PH were performed using linear regression, adjusting for potential confounders.

MAIN RESULTS

Sixty-six infants were included; 18 had PH and 48 did not. Z-score values for functional residual capacity (FRC), residual volume (RV), FRC/total lung capacity (TLC), and RV/TLC were significantly higher in infants with CDH and PH compared to those without PH. Z-score values for forced flows including forced expiratory volume in the first 0.5 sec (FEV0.5) and FEV0.5/forced vital capacity were significantly lower in infants with CDH and PH compared to those without PH. For 29 infants studied on ≥2 occasions, the slopes of FRC, RV, and TLC versus length were significantly higher in those with persistent PH compared to those without.

CONCLUSIONS

Infants with CDH and persistent PH demonstrate greater airspace overdistension with growth compared to those without. Therapies that modify disrupted pulmonary vascular and alveolar formation could potentially improve future care of these patients.

The use of human amniotic fluid stem cells as an adjunct to promote pulmonary development in a rabbit model for congenital diaphragmatic hernia

OBJECTIVE

This study aimed to evaluate the potential benefit of intra-tracheal injection of human amniotic fluid stem cells (hAFSC) on pulmonary development combined with TO in a rabbit model for CDH.

METHODS

In time-mated pregnant does a left diaphragmatic defect was created at d23 (term = 31). At d28, previously operated fetuses were assigned to either TO and injection with 70 μL of phosphate buffered saline (PBS) or 1.0 × 10(6) c-Kit positive hAFSC expressing LacZ or were left untouched (CDH). Harvesting was done at d31 to obtain their lung-to-body weight ratio (LBWR), airway and vascular lung morphometry, X-gal staining and immunohistochemistry for Ki67 and surfactant protein-B (SP-B).

RESULTS

CDH-induced pulmonary hypoplasia is countered by TO + PBS, this reverses LBWR, mean terminal bronchiole density (MTBD) and medial thickness to normal. The additional injection of hAFSC decreases MTBD and results in a non-significant decrease in muscularization of intra-acinary vessels. There were no inflammatory changes and LacZ positive hAFSC were dispersed throughout the lung parenchyma 4 days after injection.

CONCLUSION

HAFSC exert an additional effect on TO leading to a decrease in MTBD, a measure of alveolar number surrounding the terminal bronchioles, without signs of toxicity. © 2015 John Wiley & Sons, Ltd.

Prenatal prediction of pulmonary arterial hypertension in congenital diaphragmatic hernia

OBJECTIVE

To evaluate the role of prenatal prognostic markers obtained routinely by ultrasound examination and magnetic resonance imaging (MRI) in the prediction of development of postnatal pulmonary arterial hypertension (PAH) in isolated congenital diaphragmatic hernia (CDH).

METHODS

One hundred and ten cases of isolated CDH were referred to our fetal medicine unit between January 2004 and April 2013. Mortality and morbidity rates were reviewed for those presenting with postnatal PAH. The following prenatal markers were evaluated as potential predictive factors of PAH: liver position, side of the CDH defect, lung area to head circumference ratio (LHR) and observed/expected LHR (o/e-LHR), which were measured by ultrasound, and observed/expected total fetal lung volume (o/e-TFLV), which was measured by MRI. Univariable logistic regression was used to assess associations.

RESULTS

PAH was significantly associated with perinatal mortality and morbidity (P < 0.001). The occurrence of PAH decreased significantly with an increasing LHR, o/e-LHR and o/e-TFLV and was significantly increased for cases with an intrathoracic liver, but not for those with right-sided defects. Univariable regression revealed that o/e-TFLV (odds ratio (OR), 0.9 (95% CI, 0.86-0.95); P < 0.05 for percentage unit change in o/e), LHR (OR, 0.19 (95% CI, 0.09-0.40); P < 0.05 for unit change), o/e-LHR (OR, 0.95 (95% CI, 0.93-0.98); P < 0.05 for percentage unit change in o/e) and liver position (OR, 2.82 (95% CI, 1.13-7.00); P < 0.05 for intrathoracic liver) were significant predictors of subsequent PAH. No differences were found after adjusting for gestational age at delivery. The areas under the receiver-operating characteristics curve were 0.80 and 0.75 for o/e-TFLV and o/e-LHR, respectively.

CONCLUSION

In cases of CDH, PAH is associated with high rates of mortality and morbidity. Routinely obtained prenatal markers, usually used for the assessment of pulmonary hypoplasia, are also relevant for the postnatal prediction of PAH.

A role for actin polymerization in persistent pulmonary hypertension of the newborn

Persistent pulmonary hypertension of the newborn (PPHN) is defined as the failure of normal pulmonary vascular relaxation at birth. Hypoxia is known to impede postnatal disassembly of the actin cytoskeleton in pulmonary arterial myocytes, resulting in elevation of smooth muscle α-actin and γ-actin content in elastic and resistance pulmonary arteries in PPHN compared with age-matched controls. This review examines the original histological characterization of PPHN with attention to cytoskeletal structural remodeling and actin isoform abundance, reviews the existing evidence for understanding the biophysical and biochemical forces at play during neonatal circulatory transition, and specifically addresses the role of the cortical actin architecture, primarily identified as γ-actin, in the transduction of mechanical force in the hypoxic PPHN pulmonary circuit.

Histologic identification of prominent intrapulmonary anastomotic vessels in severe congenital diaphragmatic hernia

OBJECTIVE

To determine whether prominent intrapulmonary anastomotic vessels (IPAVs) or bronchopulmonary "shunt" vessels can be identified in lungs from infants with fatal congenital diaphragmatic hernia (CDH).

STUDY DESIGN

We performed histology with immunostaining for CD31 (endothelium) and D2-40 (lymphatics), along with high-precision 3-dimensional (3D) reconstruction on lung tissue from 9 patients who died with CDH.

RESULTS

Each patient with CDH required mechanical ventilation, cardiotonic support, and pulmonary hypertension (PH)-targeted drug therapy. All patients were diagnosed with severe PH by echocardiography, and 5 received extracorporeal membrane oxygenation therapy. Death occurred at a median age of 24 days (range, 10-150 days) from refractory hypoxemia with severe PH, pneumonia, or tension pneumothorax. Histology showed decreased alveolarization with pulmonary vascular disease. In each patient, prominent IPAVs were identified as engorged, thin-walled vessels that connected pulmonary veins with microvessels surrounding pulmonary arteries and airways in lungs ipsilateral and contralateral to the CDH. Prominent anastomoses between pulmonary arteries and bronchial arteries were noted as well. The 3D reconstruction studies demonstrated that IPAVs connect pulmonary vasculature to systemic (bronchial) vessels both at the arterial and venous side.

CONCLUSION

Histology and 3D reconstruction identified prominent bronchopulmonary vascular anastamoses in the lungs of infants who died with severe CDH. We speculate that IPAVs connecting pulmonary and bronchial arteries contribute to refractory hypoxemia in severe CDH.

Antenatal maternally-administered phosphodiesterase type 5 inhibitors normalize eNOS expression in the fetal lamb model of congenital diaphragmatic hernia

PURPOSE

Pulmonary hypertension (pHTN), a main determinant of survival in congenital diaphragmatic hernia (CDH), results from in utero vascular remodeling. Phosphodiesterase type 5 (PDE5) inhibitors have never been used antenatally to treat pHTN. The purpose of this study is to determine if antenatal PDE5 inhibitors can prevent pHTN in the fetal lamb model of CDH.

METHODS

CDH was created in pregnant ewes. Postoperatively, pregnant ewes received oral placebo or tadalafil, a PDE5 inhibitor, until delivery. Near term gestation, lambs underwent resuscitations, and lung tissue was snap frozen for protein analysis.

RESULTS

Mean cGMP levels were 0.53±0.11 in placebo-treated fetal lambs and 1.73±0.21 in tadalafil-treated fetal lambs (p=0.002). Normalized expression of eNOS was 82%±12% in Normal-Placebo, 61%±5% in CDH-Placebo, 116%±6% in Normal-Tadalafil, and 86%±8% in CDH-Tadalafil lambs. Normalized expression of β-sGC was 105%±15% in Normal-Placebo, 82%±3% in CDH-Placebo, 158%±16% in Normal-Tadalafil, and 86%±8% in CDH-Tadalafil lambs. Endothelial NOS and β-sGC were significantly decreased in CDH (p=0.0007 and 0.01 for eNOS and β-sGC, respectively), and tadalafil significantly increased eNOS expression (p=0.0002).

CONCLUSIONS

PDE5 inhibitors can cross the placental barrier. β-sGC and eNOS are downregulated in fetal lambs with CDH. Antenatal PDE5 inhibitors normalize eNOS and may prevent in utero vascular remodeling in CDH.

Lethal Bochdalek hernia in a three-year-old: pathological findings and medicolegal investigation in accusation of malpractice

Diaphragmatic hernias can be a pitfall for paediatric diagnostics, especially in the cases of late presentation, which can also have medico-legal ramifications as exposed. A three-year-old boy was taken to a children's hospital after an episode of abdominal pain and vomiting of food. A physical examination proved normal, with mild ketonuria being found and he was discharged. Three months later for the same signs and symptoms, he was taken once more to hospital, where he arrived in a state of cardiac arrest and died. A lawsuit was begun against the doctors who had examined him three months earlier. The autopsy found herniation of the abdominal organs into the left pleural cavity through a defect in the left hemidiaphragm. The cause of death was identified as cardiac tamponade caused by mechanical compression of multiple herniated abdominal organs. The histopathological examination revealed marked atelectasis of the left lung, with non-expansion of 60-90% of the alveoli which suggested an acute mechanism that proved fatal, and the doctors were acquitted. The features of this disease and the possible difficulties in its diagnosis highlight the need for the utmost attention in differential diagnosis, even at an age where the discovery of a diaphragmatic hernia is exceedingly rare.

Associated morbidities to congenital diaphragmatic hernia and a relationship to human milk

The majority of what is known in the recent literature regarding human milk studies in the neonatal intensive care setting is specific to term and/or preterm infants (including very-low-birth-weight preterm infants). However, there is a lack of human milk and breastfeeding literature concerning infants with congenital anomalies, specifically infants diagnosed with congenital diaphragmatic hernia (CDH). By applying human milk research conducted among other populations of infants, this article highlights how human milk may have a significant impact on infants with CDH. Recent human milk studies are reviewed and then applied to the CDH population in regard to respiratory and gastrointestinal morbidities, as well as infection and length of stay. In addition, clinical implications of these relationships are discussed and suggestions for future research are presented.

Reversal of pulmonary vascular remodeling in pulmonary hypertensive rats

Pulmonary hypertension is responsible for significant mortality and morbidity among newborns and infants. The pathology is characterized by pulmonary vascular remodeling with medial hypertrophy and adventitial thickening, leading to decreased gas exchange. Since it is unknown if these abnormalities are reversible, we analyzed these vascular changes in pulmonary hypertensive rats. Exposure of rats to hypobaric hypoxia for 4 weeks induced clinical signs of pulmonary hypertension, such as increased right ventricular systolic pressure, increased right ventricular weight and considerable pulmonary vascular remodeling. The vascular changes were associated with the expression of Non -Muscle Myosin Heavy Chain B in the pre-acinar vessels and an increased expression of alpha Smooth Muscle Actin, Smooth Muscle Myosin Heavy Chain 2 and Calponin in the intra-acinar vessels. The right ventricular systolic pressure and right ventricular weight gradually decreased after specific periods of recovery in normoxia, although this reversal did not reach baseline levels after six weeks at normoxia. However, the cellular changes in the pulmonary vasculature were completely reversed. Development of pulmonary hypertension is associated with an increase of synthetic perivascular cells in the pre-acinar arteries and an aberrant differentiation of perivascular cells in the smallest intra-acinar arteries. These cellular and structural changes in the pulmonary vasculature are completely reversible after recovery in normoxia.

Pulmonary vascular resistance in repaired congenital diaphragmatic hernia vs. age-matched controls

INTRODUCTION

Infants and children with repaired congenital diaphragmatic hernia (CDH) often continue to show delayed growth and development that may be, in part, secondary to unrecognized persistence of increased pulmonary vascular resistance (PVR).

METHODS

Data were reviewed from all patients ages 6-36 mo with repaired CDH who underwent cardiac catheterization from 2007 to 2010 and were compared to data from a control population of patients undergoing percutaneous closure of a patent ductus arteriosus (PDA). Indexed pulmonary blood flow (Qp), mean pulmonary artery pressure (mPAP), pulmonary capillary wedge pressure (PCWP), and PVR were examined.

RESULTS

Data from 8 CDH patients and 10 control patients were examined. The mPAP (22.5 ± 3.33 vs. 18.2 ± 4.13 mm Hg) and PVR (3.66 ± 0.79 vs. 1.22 ± 0.4 iwU (indexed Wood's units)) were both significantly elevated in the CDH population, whereas the Qp (4.08 ± 1.43 vs. 6.82 ± 1.46 l/min/m(2)) was significantly lower in this population. There was no significant difference in pulmonary capillary wedge pressure (PCWP). Less than half of the CDH patients had signs of pulmonary hypertension (PH) on echocardiogram.

DISCUSSION

Our data suggest that children who are ages 6-36 mo with repaired CDH have significantly increased PVR compared with controls and early consideration of cardiac catheterization may be warranted.

Congenital diaphragmatic hernia

Congenital Diaphragmatic Hernia (CDH) is defined by the presence of an orifice in the diaphragm, more often left and posterolateral that permits the herniation of abdominal contents into the thorax. The lungs are hypoplastic and have abnormal vessels that cause respiratory insufficiency and persistent pulmonary hypertension with high mortality. About one third of cases have cardiovascular malformations and lesser proportions have skeletal, neural, genitourinary, gastrointestinal or other defects. CDH can be a component of Pallister-Killian, Fryns, Ghersoni-Baruch, WAGR, Denys-Drash, Brachman-De Lange, Donnai-Barrow or Wolf-Hirschhorn syndromes. Some chromosomal anomalies involve CDH as well. The incidence is < 5 in 10,000 live-births. The etiology is unknown although clinical, genetic and experimental evidence points to disturbances in the retinoid-signaling pathway during organogenesis. Antenatal diagnosis is often made and this allows prenatal management (open correction of the hernia in the past and reversible fetoscopic tracheal obstruction nowadays) that may be indicated in cases with severe lung hypoplasia and grim prognosis. Treatment after birth requires all the refinements of critical care including extracorporeal membrane oxygenation prior to surgical correction. The best hospital series report 80% survival but it remains around 50% in population-based studies. Chronic respiratory tract disease, neurodevelopmental problems, neurosensorial hearing loss and gastroesophageal reflux are common problems in survivors. Much more research on several aspects of this severe condition is warranted.

Use of milrinone to treat cardiac dysfunction in infants with pulmonary hypertension secondary to congenital diaphragmatic hernia: a review of six patients

BACKGROUND

Pulmonary hypertension and secondary cardiac dysfunction are important contributors of morbidity and mortality in infants with congenital diaphragmatic hernia (CDH). Milrinone, a phosphodiesterase-3 inhibitor, may be useful in this setting for its combined actions as a pulmonary vasodilator and to improve systolic and diastolic function.

OBJECTIVES

This study aimed to assess the effects of milrinone on cardiac function and pulmonary artery pressure in infants with CDH.

METHODS

A retrospective review of echocardiograms performed on infants with CDH who received milrinone was performed. Tissue Doppler imaging velocities were used to assess systolic and diastolic function. Pulmonary artery pressure was assessed from the pattern and velocity of ductal shunting.

RESULTS

Six infants with CDH and severe pulmonary hypertension were identified. Systolic and diastolic myocardial velocities were reduced in the right ventricle (RV) and interventricular septum (IVS) at baseline. In the 72 h after commencement of milrinone, there was a significant increase in early diastolic myocardial velocities in the RV, accompanied by increasing systolic velocities in the RV and IVS. Oxygenation index was significantly reduced, blood pressure unchanged, and ductal shunt velocity minimally altered over the same time period.

CONCLUSIONS

Milrinone use was associated with an improvement in systolic and diastolic function in the RV, corresponding to an improvement in clinical status.

Vascular abnormalities in human newborns with pulmonary hypertension

Pulmonary vascular disease embodies all congenital or acquired pathologies that affect the pulmonary vasculature. One of them is pulmonary hypertension of the newborn (PHN), which is clinically characterized by a persistent high pulmonary vascular resistance postnatally and an abnormal vascular response. Morphologically, the vascular walls of the small pulmonary arteries become thickened, leading to increased resistance of these vessels and thus a worsening of gas exchange. PHN occurs as a primary disease or in association with abnormal lung development, for example as in congenital diaphragmatic hernia, and is a critical determinant of morbidity and mortality. Here we review the current knowledge about vascular abnormalities in PHN and discuss the vascular abnormalities in different conditions associated with pulmonary hypertension in human newborns in relation to recent findings from molecular biology.

Maternal hyperoxygenation test in fetuses undergoing FETO for severe isolated congenital diaphragmatic hernia

OBJECTIVES

To predict neonatal survival and pulmonary hypertension by measurement of fetal pulmonary artery reactivity to maternal hyperoxygenation in fetuses with severe congenital diaphragmatic hernia treated by fetoscopic endoluminal tracheal occlusion (FETO).

METHODS

Thirty-eight fetuses underwent FETO at around 28 weeks' gestation and the balloon was removed at 34 weeks in most cases. We performed a hyperoxygenation test and measured the lung-to-head ratio of each fetus before and after each procedure. Outcome measures were neonatal survival, occurrence of pulmonary hypertension and its response to inhaled nitric oxide (iNO).

RESULTS

Fetuses that survived had a larger increase in lung size and decrease of resistance in the first branch of the main pulmonary artery than did those that died. Both measures were also predictive of pulmonary hypertension unresponsive to iNO. The hyperoxygenation test and lung-to-head ratio were both best predictive for neonatal survival when measured following removal of the balloon (P < 0.002). Discriminant analysis confirmed that these two parameters are independent predictors of outcome.

CONCLUSIONS

In fetuses undergoing FETO, pulmonary vascular reactivity in relation to oxygen and lung size are independent predictors of neonatal survival and pulmonary hypertension. The hyperoxygenation test merits further study in expectantly managed cases.

Late administration of antenatal vitamin A promotes pulmonary structural maturation and improves ventilation in the lamb model of congenital diaphragmatic hernia

PURPOSE

The lungs in congenital diaphragmatic hernia (CDH) are hypoplastic and immature making respiratory support one of the most challenging aspects of caring for these neonates. Vitamin A is essential for normal lung growth and development. It also promotes alveolarization. The aim of this study is to investigate the effects of antenatal vitamin A on lung growth and alveolarization and ventilation in the lamb model of CDH.

METHODS

This study was approved by the Animal Care Committee of the State University of New York at Buffalo, and conforms to the National Institute of Health guidelines. Diaphragmatic defects were created at 79-81 days gestation. Group 1 lambs (CDH, n = 5) were untreated. In group 2 (CDH + vitamin A, n = 6) and group 3 lambs (control + vitamin A, n = 3) right jugular venous catheters were inserted at 118-120 days and retinyl palmitate (vitamin A) was administered until 135 days. The control group (n = 5) consisted of twin littermates. Lambs were delivered at 136-139 days and ventilated for 2 h according to a set protocol. The left lungs were harvested and fixed for histology.

RESULTS

Lung compliance was significantly higher in CDH + vitamin A (median 0.27, range 0.1-0.48 ml/cmH(2)O/kg) versus CDH lambs (median 0.07, range 0.07-0.18 ml/cmH(2)O/kg), P < 0.05. At 1 h CDH + vitamin A lambs experienced significantly lower PaCO(2) (median 115, range 35-194 mmHg vs. median 192, range 168-234 mmHg) and higher arterial pH (median 7.0, range 6.74-7.35 vs. median 6.73, range 6.5-6.81) than CDH lambs, P < 0.05. The lung weight to body weight ratio of CDH + vitamin A lambs was significantly less than that of CDH lambs (P < 0.05). Histology showed small thick walled air-spaces and no true alveoli in CDH lambs. In contrast, true alveoli and thinning of the inter-alveolar septums were seen in CDH + vitamin A lambs.

CONCLUSION

This is the first study to demonstrate an improvement in lung function and structural maturation when antenatal vitamin A is given in a surgical model of CDH.

Upregulation of endothelin receptors A and B in the nitrofen induced hypoplastic lung occurs early in gestation

PURPOSE

Pulmonary hypoplasia and persistent pulmonary hypertension (PPH) aggravate clinical courses in congenital diaphragmatic hernia (CDH). Endothelin 1 enhances PPH by vasoconstriction and proliferation of vessel walls. Up-regulation of pulmonary Endothelin Receptors A and B (EDNRA, EDNRB) has been reported in human CDH and animal models, but the onset of those alterations during lung development remains unclear. We hypothesized that pulmonary expression of EDNRA and EDNRB is up-regulated at early gestational stages in the nitrofen model.

METHODS

Pregnant rats were exposed to nitrofen or vehicle on gestational day 9 (D9). Embryos were sacrificed on D15, D18 and D21 and divided into nitrofen- and control group. Pulmonary RNA was extracted and mRNA levels of EDNRA and EDNRB were determined by real-time PCR. Immunohistochemistry for protein expression of both receptors was performed.

RESULTS

mRNA levels of EDNRA and EDNRB were significantly increased in the nitrofen group on D15, D18 and D21. Immunohistochemistry revealed increased pulmonary vascular expression of EDNRA and EDNRB compared to controls.

CONCLUSION

Altered expression of EDNRA and EDNRB is an early event in lung morphogenesis in the nitrofen model. We speculate that pulmonary arteries in CDH become excessively muscularised in early fetal life, becoming unable to adapt normally at birth.

Congenital diaphragmatic hernia: current status and review of the literature

Treatment of congenital diaphragmatic hernia (CDH) challenges obstetricians, pediatric surgeons, and neonatologists. Persistent pulmonary hypertension (PPHT) associated with lung hypoplasia in CDH leads to a high mortality rate at birth. PPHT is principally due to an increased muscularization of the arterioles. Management of CDH has been greatly improved by the introduction of prenatal surgical intervention with tracheal obstruction (TO) and by more appropriate postnatal care. TO appears to accelerate fetal lung growth and to increase the number of capillary vessels and alveoli. Improvement of postnatal care over the last years is mainly due to the avoidance of lung injury by applying low peak inflation pressure during ventilation. The benefits of other drugs or technical improvements such as the use of inhaled nitric oxide or extracorporeal membrane oxygenation (ECMO) are still being debated and no single strategy is accepted worldwide. Despite intensive clinical and experimental research, the treatment of newborn with CDH remains difficult.

The long-term follow-up of patients with a congenital diaphragmatic hernia: a broad spectrum of morbidity

Congenital diaphragmatic hernia (CDH) is a life-threatening anomaly with a mortality rate of approximately 40-50%, depending on case selection. It has been suggested that new therapeutic modalities such as nitric oxide (NO), high frequency oxygenation (HFO) and extracorporal membrane oxygenation (ECMO) might decrease mortality associated with pulmonary hypertension and the sequelae of artificial ventilation. When these new therapies indeed prove to be beneficial, a larger number of children with severe forms of CDH might survive, resulting in an increase of CDH-associated complications and/or consequences. In follow-up studies of infants born with CDH, many complications including pulmonary damage, cardiovascular disease, gastro-intestinal disease, failure to thrive, neurocognitive defects and musculoskeletal abnormalities have been described. Long-term pulmonary morbidity in CDH consists of obstructive and restrictive lung function impairments due to altered lung structure and prolonged ventilatory support. CDH has also been associated with persistent pulmonary vascular abnormalities, resulting in pulmonary hypertension in the neonatal period. Long-term consequences of pulmonary hypertension are unknown. Gastro-esophageal reflux disease (GERD) is also an important contributor to overall morbidity, although the underlying mechanism has not been fully understood yet. In adult CDH survivors incidence of esophagitis is high and even Barrett's esophagus may ensue. Yet, in many CDH patients a clinical history compatible with GERD seems to be lacking, which may result in missing patients with pathologic reflux disease. Prolonged unrecognized GERD may eventually result in failure to thrive. This has been found in many young CDH patients, which may also be caused by insufficient intake due to oral aversion and increased caloric requirements due to pulmonary morbidity. Neurological outcome is determined by an increased risk of perinatal and neonatal hypoxemia in the first days of life of CDH patients. In patients treated with ECMO, the incidence of neurological deficits is even higher, probably reflecting more severe hypoxemia and the risk of ECMO associated complications. Many studies have addressed the substantial impact of the health problems described above, on the overall well-being of CDH patients, but most of them concentrate on the first years after repair and only a few studies focus on the health-related quality of life in CDH patients. Considering the scattered data indicating substantial morbidity in long-term survivors of CDH, follow-up studies that systematically assess long-term sequelae are mandatory. Based on such studies a more focused approach for routine follow-up programs may be established.

Fetal tracheal occlusion for severe congenital diaphragmatic hernia in humans: a morphometric study of lung parenchyma and muscularization of pulmonary arterioles

OBJECTIVE

The aim of this study is to examine structure of lung parenchyma (Pp) and muscularization of pulmonary arterioles (PAs) in human fetuses that underwent tracheal occlusion (TO) therapy for severe congenital diaphragmatic hernia (CDH).

MATERIAL

Fifteen fetuses underwent TO, with 5 survivors (Am J Obstet Gynecol. 2000:183;1059-1066). Paraffin-embedded lung specimens from 7 of 10 nonsurvivors (CDH-TO) and 6 age-matched fetuses (CDH) were available for morphometric analysis, which included measurements of point fraction of lung Pp and surface density. The PAs were categorized according to external diameter (<70 microm and 70 <or= 140 microm). Percent medial wall thickness (%MWT) was calculated by dividing raw measurements of MWT by external diameter.

RESULTS

Gestational age at TO was 27.6 +/- 0.9 weeks with a mean duration of TO of 32.6 +/- 6.8 days. Gestational age at delivery (CDH-TO 31.9 +/- 0.9 vs CDH 35.4 +/- 1.8 weeks; P = .18) and postnatal survival time (CDH-TO 20.5 +/- 6.0 vs CDH 18.6 +/- 7.8 days; P = .85) were not significantly different between groups. Tracheal occlusion significantly increased the lung-to-body weight ratio (CDH-TO 13.0 +/- 2.2 vs CDH 6.6 +/- 0.9; P = .02). Tracheal occlusion tended to decrease right-lung Pp (CDH-TO 54.6% +/- 2.6% vs CDH 65.7% +/- 5.9%; P = .05), whereas left-lung Pp was not different between groups (CDH-TO 63.0% +/- 3.5% vs CDH 66.7% +/- 4.1%; P = .51). Surface density of airspaces was not different between groups in either left (CDH-TO 171.3 +/- 16.1 cm(-1) vs CDH 151.1 +/- 8.1 cm(-1); P = .34) or right (CDH-TO 172.0 +/- 10.6 cm(-1) vs CDH 160.8 +/- 3.6 cm(-1); P = .33) lungs. The %MWT in small and large PA was similar between groups.

CONCLUSIONS

Open prenatal TO in human fetuses increased lung growth, as evidenced by an increase in lung weight, but did not improve parenchymal structure or muscularization of PAs.

Resting and exercise cardiorespiratory function in survivors of congenital diaphragmatic hernia

Our objective was to study exercise capacity and cardiorespiratory response to exertion in survivors of congenital diaphragmatic hernia (CDH). This was a cross-sectional cohort study of 23 CDH survivors, aged 10-16 years, and 23 gender- and age-matched controls. Exercise testing was performed on a cycle ergometer, with cardiac output measurements made using exponential CO2 rebreathing. Pretest cardiorespiratory assessment was done by echocardiography and pulmonary function testing. Statistical analysis was performed using Student's t-test, regression analysis, and longitudinal model computing with spatial covariance structure. No echocardiographic evidence for pulmonary hypertension was found at rest (right ventricular systolic pressures, 27 +/- 6 mmHg). Mean pulmonary artery diameter on the side of the CDH was significantly smaller than contralaterally, but was within normal range (z-score, 0 +/- 1.1 vs. 1.2 +/- 1.6, P < 0.01). Exercise capacity was mildly reduced in CDH compared to controls and predictive data (maximum workload, 77% +/- 12% vs. 91% +/- 16% of predicted, P < 0.01). Cardiorespiratory response to exertion was not significantly different between groups. In conclusion, most adolescent CDH survivors have nearly normal exercise capacity and cardiorespiratory response to exertion. This study may prove useful in comparisons with future cohorts comprising more severely affected individuals now surviving due to improved neonatal care.

Effect of VEGF on the branching morphogenesis of normal and nitrofen-induced hypoplastic fetal rat lung explants

PURPOSE

Changes in vascular structures as well as vascular endothelial growth factor (VEGF) downregulation have been reported in hypoplastic lungs associated with congenital diaphragmatic hernia. We hypothesized that VEGF may accelerate branching morphogenesis and thus may modulate lung growth in normal and nitrofen-induced pulmonary hypoplastic lungs.

METHODS

A hypoplastic fetal lung model and a normal control lung model were induced by feeding pregnant rats with or without nitrofen, respectively. Fetal lungs harvested on day 13.5 were cultured at ambient oxygen tensions for 72 hours with 0, 25, 50, or 100 ng/mL of exogenous rat VEGF added daily in the serum-free medium. The rates of increase in bud count and airway contour were evaluated. Real-time polymerase chain reaction was carried out to evaluate the expression of surfactant protein C mRNA in the explants at the end of culture.

RESULTS

Vascular endothelial growth factor accelerated the increase in bud count and airway contour in normal and hypoplastic lung explants compared to controls. Surfactant protein C mRNA expression was significantly increased at 50 ng/mL VEGF compared to controls in both normal and hypoplastic lung explants.

CONCLUSION

These data suggest that VEGF plays an important role in lung morphogenesis and may accelerate lung growth in nitrofen-induced hypoplastic lung.

The distribution of matrix metalloproteinases and tissue inhibitors of metalloproteinases in the lungs of congenital diaphragmatic hernia patients and age-matched controls

AIMS

In congenital diaphragmatic hernia (CDH), the pathogenesis of abnormal pulmonary morphology is still incompletely understood. Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) are known to play an important role in the turnover of the extracellular matrix (ECM) during development and in remodelling of tissue. The aim of this study was to investigate differences in the expression of MMPs and TIMPs between CDH lungs and controls, against the background of the abnormal pulmonary vasculature in CDH.

METHODS

We studied 12 lungs of term CDH patients who died < 24 h after birth and 11 normal age-matched control lungs, by immunohistochemistry with antibodies against human MMP-1, -2, -9, TIMP-1 and -2.

RESULTS

There was a clear increase in the number of MMP-1-reactive capillaries and fibroblasts in CDH lungs compared with controls. In contrast, TIMP-2 reactivity in these structures was decreased in CDH lungs. The arterial endothelium and medial smooth muscle expressed MMP-2, -9 and TIMP-2 in both CDH and control lungs. In small arteries (< 100 microm in diameter), the positive surface area of MMP-2, -9 and TIMP-2 was significantly larger in CDH lungs than in controls. There was no difference in the distribution and expression of TIMP-1 between CDH lungs and normal controls.

CONCLUSION

The differences in staining pattern of MMPs and TIMPs between normal and CDH lungs suggest that these enzymes might play a role in the abnormal remodelling of the interstitium and the pulmonary arteries in CDH lungs. This could contribute to our understanding of the abnormal lung morphology and the occurrence of pulmonary hypertension, which forms one of the major obstacles to the successful treatment of these patients.

Endothelin receptor expression in human lungs of newborns with congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a major cause of refractory respiratory failure in the neonatal period and is characterized by persistent pulmonary hypertension of the newborn (PPHN) and pulmonary hypoplasia. Endothelin-1 (ET-1) dysregulation may play a significant role in the pathophysiology of PPHN and ET-1 acts through binding to type A (ETA) and type B (ETB) receptors. Therefore, ETA and ETB receptor protein expression was studied using immunohistochemistry in 10 lung specimens obtained from newborns with CDH, and 4 normal lung specimens, in order to explore whether dysregulation of ETA and ETB expression contributes to PPHN. ETA and ETB mRNAs were then quantified using real-time RT-PCR in laser-microdissected pulmonary resistive arteries. In the lungs of newborns with CDH, immunohistochemistry of both ETA and ETB receptors demonstrated over-expression in the thickened media of pulmonary arteries. Using laser microdissection and real-time RT-PCR, higher levels of ETA and ETB mRNA were found in CDH pulmonary arteries than in controls: this increase was more pronounced for ETA mRNA. This study provides the first demonstration of ET-1 receptor dysregulation in association with structural alteration of pulmonary arteries in newborns with CDH and PPHN. This dysregulation preferentially affects the ETA receptor. These results suggest that dysregulation of ET-1 receptors may contribute to PPHN associated with CDH.

Comparison between three-dimensional volume-selective turbo spin-echo imaging and two-dimensional ultrasound for assessing carotid artery structure and function

PURPOSE

To compare a volume-selective three-dimensional turbo spin echo (TSE) technique with ultrasound (US) for assessing carotid artery wall structure and function.

MATERIALS AND METHODS

A three-dimensional volume-selective TSE technique was used to image the carotid artery in 10 healthy subjects and five hypertensive subjects (each of whom were scanned three times while they received different hypertension treatments). Lumen and wall area were measured on MR images. Two-dimensional US measurements of the intima-media thickness (IMT) and lumen diameter were taken in three orientations through a single cross section. The lumen area change over the cardiac cycle was used to determine distension. For validation, a Bland-Altman analysis was used to compare the vessel wall and lumen areas measured by three-dimensional MRI volumes with those obtained by US scans.

RESULTS

Agreement between the two methods was found. The mean difference in distension between US and MRI was 1.2% (+/-5.1%). For the wall area measurements, good agreement was shown, but there was a systematic difference due to the visualization of the adventitia by MRI. Both techniques offer an easy way to objectively measure lumen indices. MRI can provide the complete circumference over the length of a vessel, while US is flexible and relatively inexpensive. The application of US is limited, however, when subjects are poorly echogenic. A difference between hypertensive and healthy subjects was found.

CONCLUSION

There was a good agreement between MRI and the clinically established two-dimensional US method. The MRI method has the advantage of providing increased vessel coverage, which permits one to assess localized abnormalities without assuming vessel uniformity.

Pulmonary vascular morphology in a fetal rabbit model for congenital diaphragmatic hernia

BACKGROUND/PURPOSE

Although the pulmonary vascular abnormalities in congenital diaphragmatic hernia (CDH) are described from a morphologic point of view, the treatment of pulmonary hypertension (PH) remains one of the main unsolved problems in clinical daily practice. For this reason, detailed studies in well-validated animal models could still be of significance in our understanding of the pathogenesis of CDH.

METHODS

In does of 23 days' gestational age (GA), 39 fetuses underwent creation of diaphragmatic hernia (DH) and 15 fetuses a sham thoracotomy (SHAM). Thirty-nine nonoperated littermates served as internal controls (CTR). Fetuses were harvested by cesarean section on days 25, 27, 29, and 30 of gestation. Lung specimens were obtained and formalin fixed for further vascular morphometry studies.

RESULTS

Lung vessels from DH fetuses started to show significantly smaller internal diameter (ID), external diameter (ED), larger arterial wall thickness (WT), and, in particular, a proportionally higher medial thickness (%MT) and adventitial thickness (%AT) from day 27 onward when compared with control fetuses. SHAM fetuses, which were harvested at term, showed no differences with CTR.

CONCLUSIONS

This is the first report documenting changes over time in the vascular system in a rabbit fetal model of surgically induced DH. These changes mimic pathologic findings observed in human fetuses and are also concordant with earlier observations in the surgical ovine model and the toxic nitrofen rat model.