Tracheal side effects following fetal endoscopic tracheal occlusion for severe congenital diaphragmatic hernia

Tracheomalacia and tracheomegaly in infants and children with congenital diaphragmatic hernia managed with and without fetoscopic endoluminal tracheal occlusion (FETO): a multicentre, retrospective cohort study

BACKGROUND

Temporary fetoscopic endoluminal tracheal occlusion (FETO) promotes lung growth and increases survival in selected fetuses with congenital diaphragmatic hernia (CDH). FETO is performed percutaneously by inserting into the trachea a balloon designed for vascular occlusion. However, reports on the potential postnatal side-effects of the balloon are scarce. This study aimed to evaluate the prevalence of tracheomalacia in infants with CDH managed with and without FETO and other consequences related to the use of the balloon.

METHODS

In this multicentre, retrospective cohort study, we included infants who were live born with CDH, either with FETO or without, who were managed postnatally at four centres (UZ Leuven, Leuven, Belgium; Antoine Béclère, Clamart, France; BCNatal, Barcelona, Spain; and HCor-Heart Hospital, São Paulo, Brazil) between April 5, 2002, and June 2, 2021. We primarily assessed the prevalence of all (symptomatic and asymptomatic) tracheomalacia as reported in medical records among infants with and without FETO. Secondarily we assessed the prevalence of symptomatic tracheomalacia and its resolution as reported in medical records, and compared tracheal diameters as measured on postnatal x-rays. Crude and adjusted risk ratios (aRRs) and 95% CIs were calculated via modified Poisson regression models with robust error variances for potential association between FETO and tracheomalacia. Variables included in the adjusted model were the side of the hernia, observed-to-expected lung-to-head ratio, and gestational age at birth. Crude and adjusted mean differences and 95% CIs were calculated via linear regression models to assess the presence and magnitude of association between FETO and tracheal diameters. In infants who had undergone FETO we also assessed the localisation of balloon remnants on x-rays, and the methods used for reversal of occlusion and potential complications associated with balloon remnants as documented in clinical records. Finally we investigated whether the presence of balloon remnants was influenced by the interval between balloon removal and delivery.

FINDINGS

505 neonates were included in the study, of whom 287 had undergone FETO and 218 had not. Tracheomalacia was reported in 18 (6%) infants who had undergone FETO and in three (1%) who had not (aRR 6·17 [95% CI 1·83-20·75]; p=0·0030). Tracheomalacia was first reported in the FETO group at a median of 5·0 months (IQR 0·8-13·0). Symptomatic tracheomalacia was reported in 13 (5%) infants who had undergone FETO, which resolved in ten (77%) children by 55·0 months (IQR 14·0-83·0). On average, infants who had undergone FETO had a 31·3% wider trachea (with FETO tracheal diameter 7·43 mm [SD 1·24], without FETO tracheal diameter 5·10 mm [SD 0·84]; crude mean difference 2·32 [95% CI 2·11-2·54]; p<0·0001; adjusted mean difference 2·62 [95% CI 2·35-2·89]; p<0·0001). At birth, the metallic component was visible within the body in 75 (37%) of 205 infants with available thoraco-abdominal x-rays: it was located in the gastrointestinal tract in 60 (80%) and in the lung in 15 (20%). No side-effects were reported for any of the infants during follow-up. The metallic component was more likely to be in the lung than either outside the body or the gastrointestinal tract when the interval between occlusion reversal and birth was less than 24 h.

INTERPRETATION

Although FETO was associated with an increased tracheal diameter and an increased probability of tracheomalacia, symptomatic tracheomalacia typically resolved over time. There is a higher risk of retention of metallic balloon components if reversal of the occlusion occurs less than 24 h before delivery. Finally, there were no reported side-effects of the metallic component of the balloon persisting in the body during follow-up. Longer-term follow-up is needed to ensure that no tracheal problems arise later in life.

FUNDING

None.

Congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a rare developmental defect of the diaphragm, characterized by the herniation of abdominal contents into the chest, resulting in varying degrees of pulmonary hypoplasia and pulmonary hypertension. Significant advances in the prenatal diagnosis and identification of prognostic factors have resulted in the continued refinement of the approach to fetal therapies for CDH. In the postnatal period, protocolized approaches to lung-protective ventilation, nutrition, prevention of infection, and early aggressive management of pulmonary hypertension have led to improved outcomes in infants with CDH. Surgical repair of CDH is not urgent in most circumstances and can be delayed until the pulmonary status of the patient has stabilized. This article provides a comprehensive review of CDH, focusing on the complex pathophysiology, advances in prenatal diagnosis, fetal interventions, and optimal postnatal management of CDH.

Fetal endoscopic tracheal occlusion for congenital diaphragmatic hernia: a narrative review of the history, current practice, and future directions

Fetal intervention for fetuses with congenital diaphragmatic hernia (CDH) has been investigated for over 30 years and is summarized in this manuscript. The review begins with a discussion of the history of fetal intervention for this severe congenital anomaly beginning with open fetal surgery with repair of the anatomical defect, shifting towards tracheal occlusion via open surgery techniques, and finally fetoscopic endoluminal balloon tracheal occlusion using a percutaneous approach. The current technique of fetal endoscopic tracheal occlusion (FETO) is described in detail with steps of the procedure and complementary figures. The main outcomes of single-institutional studies and multiple systematic reviews are examined and discussed. Despite these studies, the fetal community agrees that FETO remains investigational at this time as there is insufficient evidence to recommend it as the standard of care for CDH. A randomized controlled trial, The Tracheal Occlusion to Accelerate Lung Growth (TOTAL) trial, has been designed to attempt to answer this question in an elaborate, international, multi-institutional study and is described in the text. Finally, future directions of fetal intervention for antenatally diagnosed CDH are discussed, including options for non-isolated CDH, the Smart-TO balloon for nonoperative reversal of occlusion, and transplacental sildenafil for treatment of pulmonary hypertension prior to birth.

Safety and efficacy of smart tracheal occlusion device in diaphragmatic hernia lamb model

OBJECTIVE

To investigate the efficacy and safety of the 'smart' tracheal occlusion (Smart-TO) device in fetal lambs with diaphragmatic hernia (DH).

METHODS

DH was created in fetal lambs on gestational day 70 (term, 145 days). Fetuses were allocated to either pregnancy continuation until term (DH group) or fetoscopic endoluminal tracheal occlusion (TO), performed using the Smart-TO balloon on gestational day 97 (DH + TO group). On gestational day 116, the presence of the balloon was confirmed on ultrasound, then the ewe was walked around a 3.0-Tesla magnetic resonance scanner for balloon deflation, which was confirmed by ultrasound immediately afterwards. At term, euthanasia was performed and the fetus retrieved. Efficacy of occlusion was assessed by the lung-to-body-weight ratio (LBWR) and lung morphometry. Safety parameters included tracheal side effects assessed by morphometry and balloon location after deflation. The unoccluded DH lambs served as a comparator.

RESULTS

Six fetuses were included in the DH group and seven in the DH + TO group. All balloons deflated successfully and were expelled spontaneously from the airways. In the DH + TO group, in comparison to controls, the LBWR at birth was significantly higher (1.90 (interquartile range (IQR), 1.43-2.55) vs 1.07 (IQR, 0.93-1.46); P = 0.005), while on lung morphometry, the alveolar size was significantly increased (mean linear intercept, 47.5 (IQR, 45.6-48.1) vs 41.9 (IQR, 38.8-46.1) μm; P = 0.03); whereas airway complexity was lower (mean terminal bronchiolar density, 1.56 (IQR, 1.0-1.81) vs 2.23 (IQR, 2.14-2.40) br/mm² ; P = 0.005). Tracheal changes on histology were minimal in both groups, but more noticeable in fetal lambs that underwent TO than in unoccluded lambs (tracheal score, 2 (IQR, 1-3) vs 0 (0-1); P = 0.03).

CONCLUSIONS

In fetal lambs with DH, TO using the Smart-TO balloon is effective and safe. Occlusion can be reversed non-invasively and the deflated intact balloon expelled spontaneously from the fetal upper airways. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Congenital diaphragmatic hernia: current management strategies from antenatal diagnosis to long-term follow-up

Congenital diaphragmatic hernia (CDH) is a developmental birth defect consisting of a diaphragmatic defect and abnormal lung development. CDH complicates 2.3-2.8 per 10,000 live births. Despite efforts to standardize clinical practice, management of CDH remains challenging. Frequent re-evaluation of clinical practices in CDH reveals that management of CDH is evolving from one of postnatal stabilization to prenatal optimization. Translational research reveals promising avenues for in utero therapeutic intervention, including fetoscopic endoluminal tracheal occlusion. These remain highly experimental and demand improved antenatal diagnostics. Timely diagnosis of CDH and identification of severely affected fetuses allow time for delivery planning or in utero therapeutics. Optimal perinatal care and surgical treatment strategies are highly debated. Improved CDH mortality rates have placed increased emphasis on identifying and monitoring the long-term sequelae of disease throughout childhood and into adulthood. We review the current management strategies for CDH, highlighting where progress has been made, and where future developments have the potential to revolutionize care in this vulnerable patient population.

Prenatal diagnosis and management of congenital diaphragmatic hernia

Congenital diaphragmatic hernia is characterized by failed closure of the diaphragm, thereby allowing abdominal viscera to herniate into the thoracic cavity and subsequently interfering with normal lung development. At birth, pulmonary hypoplasia leads to respiratory insufficiency and persistent pulmonary hypertension (PHT), that is lethal in up to 32% of patients. In isolated cases, the outcome may be predicted prenatally by medical imaging and advanced genetic testing. In those fetuses with a predicted poor outcome, fetoscopic endoluminal tracheal occlusion may be offered. This procedure is currently being evaluated in a global randomized clinical trial (www.TOTALtrial.eu). We are currently investigating alternative strategies including transplacental sildenafil administration to reduce the occurrence of persistent PHT.

Longitudinal changes in lung size and intrapulmonary-artery Doppler during the second half of pregnancy in fetuses with congenital diaphragmatic hernia

OBJECTIVES

The objectives of the study are to evaluate longitudinal changes in lung size and intrapulmonary-artery (IPa) Doppler in fetuses with congenital diaphragmatic hernia (CDH) and assess their contribution in predicting neonatal survival.

METHODS

The observed/expected lung-to-head ratio (O/E-LHR) and IPa-pulsatility index (PI) and peak early diastolic reversed flow (PEDRF) were evaluated in a cohort of left-sided CDH fetuses managed expectantly during pregnancy. Longitudinal changes were analyzed by multilevel analysis, and their value to predict survival using the multiple logistic regression and decision-tree analysis was assessed.

RESULTS

A total of 232 scans were performed on 69 CDH fetuses. The O/E-LHR values remained unchanged during fetal monitoring, whereas IPa-PI and PEDRF showed a progressive increase throughout follow-up, becoming abnormal on average at 30 weeks of gestation. Absent/reversed end-diastolic velocity (EDV) in the IPa was observed in 20.3%. O/E-LHR and IPa Doppler indices were significantly associated with probability of survival (O/E-LHR ≥ 26%, odds ratio [OR] 19.0; IPa-PI <+2.0 z score, OR 3.0; and positive EDV, OR 7.4). All cases with IPa-reversed EDV died after birth.

CONCLUSION

While lung size remains stable during pregnancy, CDH fetuses show progressive deterioration in intrapulmonary blood flow. IPa Doppler evaluation may aid in predicting survival of CDH fetuses managed expectantly during pregnancy.

Fetoscopic endoluminal tracheal occlusion and reestablishment of fetal airways for congenital diaphragmatic hernia

Background

Congenital diaphragmatic hernia (CDH) is a congenital anomaly with high mortality and morbidity mainly due to pulmonary hypoplasia and hypertension. Temporary fetal tracheal occlusion to promote prenatal lung growth may improve survival. Entrapment of lung fluid stretches the airways, leading to lung growth.

Methods

Fetal endoluminal tracheal occlusion (FETO) is performed by percutaneous sono-endoscopic insertion of a balloon developed for interventional radiology. Reversal of the occlusion to induce lung maturation can be performed by fetoscopy, transabdominal puncture, tracheoscopy, or by postnatal removal if all else fails.

Results

FETO and balloon removal have been shown safe in experienced hands. This paper deals with the technical aspects of balloon insertion and removal. While FETO is invasive, it has minimal maternal risks yet can cause preterm birth potentially offsetting its beneficial effects.

Conclusion

For left-sided severe and moderate CDH, the procedure is considered investigational and is currently being evaluated in a global randomized clinical trial (https://www.totaltrial.eu/). The procedure can be clinically offered to fetuses with severe right-sided CDH.

Prenatal management of the fetus with isolated congenital diaphragmatic hernia in the era of the TOTAL trial

Congenital diaphragmatic hernia (CDH) may be isolated or associated with other structural anomalies, the latter with poor prognosis. The defect allows viscera to herniate through the defect into the chest, competing for space with the developing lungs. At birth, pulmonary hypoplasia leads to respiratory insufficiency and persistent pulmonary hypertension that is lethal in up to 30% of patients. When isolated, survival chances can be predicted by antenatal measurement of lung size and liver herniation. Chromosomal microarrays and exome sequencing contribute to understanding genetic factors underlying isolated CDH. Prenatal intervention aims at stimulating lung development, clinically achieved by percutaneous fetal endoscopic tracheal occlusion (FETO) under local anesthesia. The Tracheal Occlusion To Accelerate Lung growth trial (www.totaltrial.eu) is an international randomized trial investigating the role of fetal therapy for severe and moderate pulmonary hypoplasia. Despite an apparent increase in survival following FETO, the search for lesser invasive and more potent prenatal interventions must continue.

Predictors of neonatal morbidity in fetuses with severe isolated congenital diaphragmatic hernia undergoing fetoscopic tracheal occlusion

OBJECTIVES

To investigate neonatal morbidity in fetuses with severe congenital diaphragmatic hernia (CDH) treated with fetoscopic endoluminal tracheal occlusion (FETO) and compare it with historical controls with less severe forms of CDH that were managed expectantly.

METHODS

This was a prospective, multicenter study on neonatal outcomes and prenatal predictors in 90 FETO survivors (78 left-sided, 12 right) and 41 controls from the antenatal CDH registry with either severe or moderate hypoplasia who were managed expectantly. We also investigated early neonatal morbidity indicators, including the need for patch repair, duration of mechanical ventilation and supplemental oxygen, age at full enteral feeding and incidence of pulmonary hypertension.

RESULTS

Gestational age at delivery was predictive of duration of assisted ventilation (P = 0.046), days on supplemental oxygen (P = 0.019) and age at full enteral feeding (P = 0.020). When delivery took place after 34 weeks' gestation, neonatal morbidity of FETO cases was comparable with that of expectantly managed cases with moderate hypoplasia.

CONCLUSIONS

Fetal intervention for severe CDH is associated with neonatal morbidity that is comparable with that of an expectantly managed group with less severe disease.

Evaluation of histological changes after tracheal occlusion at different gestational ages in a fetal rat model

OBJECTIVES

To evaluate the histological changes of tracheal cartilage and epithelium caused by tracheal occlusion at different gestational ages in a fetal rat model.

METHODS

Rat fetuses were divided into two groups: a) External control, composed of non-operated rats, and b) Interventional group, composed of rats operated upon on gestational day 18.5 (term = 22 days), divided into triads: 1) Tracheal occlusion, 2) Internal control and 3) Sham (manipulated but not operated). Morphological data for body weight, total lung weight and total lung weight/body weight ratio were collected and measured on gestational days 19.5, 20.5 and 21.5. Tracheal samples were histologically processed, and epithelial, chondral and total tracheal thicknesses were measured on each gestational day.

RESULTS

The tracheal occlusion group exhibited an increase in total lung weight/body weight ratio (p<0.001). Histologically, this group had a thicker epithelial thickness (p<0.05) and thinner chondral (p<0.05) and total tracheal thicknesses (p<0.001). These differences were more prominent on gestational days 20.5 and 21.5.

CONCLUSION

Tracheal occlusion changed tracheal morphology, increased epithelial thickness and considerably decreased total tracheal thickness. These changes in the tracheal wall could explain the development of tracheomegaly, recently reported in some human fetuses subjected to tracheal occlusion.

A randomized controlled trial of fetal endoscopic tracheal occlusion versus postnatal management of severe isolated congenital diaphragmatic hernia

OBJECTIVE

Severe pulmonary hypoplasia and pulmonary arterial hypertension are associated with reduced survival in congenital diaphragmatic hernia (CDH). We aimed to determine whether fetal endoscopic tracheal occlusion (FETO) improves survival in cases of severe isolated CDH.

METHODS

Between May 2008 and July 2010, patients whose fetuses had severe isolated CDH (lung-to-head ratio < 1.0, liver herniation into the thoracic cavity and no other detectable anomalies) were assigned randomly to FETO or to no fetal intervention (controls). FETO was performed under maternal epidural anesthesia supplemented with fetal intramuscular anesthesia. Tracheal balloon placement was achieved with ultrasound guidance and fetoscopy between 26 and 30 weeks of gestation. All cases that underwent FETO were delivered by the EXIT procedure. Postnatal therapy was the same for both treated fetuses and controls. The primary outcome was survival to 6 months of age. Other maternal and neonatal outcomes were also evaluated.

RESULTS

Twenty patients were enrolled randomly to FETO and 21 patients to standard postnatal management. The mean gestational age at randomization was similar in both groups (P = 0.83). Delivery occurred at 35.6 ± 2.4 weeks in the FETO group and at 37.4 ± 1.9 weeks in the controls (P < 0.01). In the intention-to-treat analysis, 10/20 (50.0%) infants in the FETO group survived, while 1/21 (4.8%) controls survived (relative risk (RR), 10.5 (95% CI, 1.5-74.7), P < 0.01). In the received-treatment analysis, 10/19 (52.6%) infants in the FETO group and 1/19 (5.3%) controls survived (RR, 10.0 (95% CI, 1.4-70.6) P < 0.01).

CONCLUSION

FETO improves neonatal survival in cases with isolated severe CDH.

Results of fetal endoscopic tracheal occlusion for congenital diaphragmatic hernia and the set up of the randomized controlled TOTAL trial

In isolated congenital diaphragmatic hernia, lung size and/or the position of the liver are predictive of neonatal outcome. Percutaneous Fetal Endoscopic Tracheal Occlusion (FETO) by a balloon can be undertaken to prompt lung growth in the worst cases. The feasibility and safety of FETO is no longer at stake, and it is associated with an apparent increase in neonatal survival. The gestational age at birth, the pre-existing lung size, the ability to remove the balloon prior to birth, and the lung response are predicting outcome. The most frequent complication is preterm premature rupture of the membranes, and as a consequence preterm delivery, which also complicates balloon removal. We have set up a randomized trial for the formal evaluation of FETO in Europe, including criteria for fetoscopy centers. Training of European as well as North American centers is taking place, so that the procedure could be safely and more widely offered.

Bronchomegaly as a complication of fetal endoscopic tracheal occlusion. A caution and a possible solution

Fetal medicine is developing rapidly and aims to improve the outcome for fetuses with congenital anomalies. Fetal endoscopic tracheal occlusion (FETO) has been developed for fetuses with congenital diaphragmatic hernia to counterbalance the compression of the lung by the abdominal viscera, preserving the pulmonary maturation. Because the perinatal morbidity and mortality of patients treated with FETO have decreased, new complications are emerging in the older survivors. Tracheomegaly has been reported to be a late complication of FETO, sometimes requiring tracheostomy. We report a case of bronchial dilatation after FETO and suggest an alternative surgical treatment.

Technical aspects of fetal endoscopic tracheal occlusion for congenital diaphragmatic hernia

In isolated congenital diaphragmatic hernia, prenatal prediction is made based on measurements of lung size and the presence of liver herniation into the thorax. A subset of fetuses likely to die in the postnatal period is eligible for fetal intervention that can promote lung growth. Rather than anatomical repair, this is now attempted by temporary fetal endoscopic tracheal occlusion (FETO). Herein we describe purpose-designed instruments that were developed thanks to a grant from the European Commission. The feasibility and safety of FETO have now been demonstrated in several active fetal surgery programs. The most frequent complication of the procedure is preterm premature rupture of the membranes, which is probably iatrogenic in nature. It does have an impact on gestational age at delivery and complicates balloon removal. FETO is associated with an apparent increase in survival compared with same severity controls, although this needs to be evaluated in a formal trial. The time has come to do so.

The making of fetal surgery

Fetal diagnosis prompts the question for fetal therapy in highly selected cases. Some conditions are suitable for in utero surgical intervention. This paper reviews historically important steps in the development of fetal surgery. The first invasive fetal intervention in 1963 was an intra-uterine blood transfusion. It took another 20 years to understand the pathophysiology of other candidate fetal conditions and to develop safe anaesthetic and surgical techniques before the team at the University of California at San Francisco performed its first urinary diversion through hysterotomy. This procedure would be abandoned as renal and pulmonary function could be just as effectively salvaged by ultrasound-guided insertion of a bladder shunt. Fetoscopy is another method for direct access to the feto-placental unit. It was historically used for fetal visualisation to guide biopsies or for vascular access but was also abandoned following the introduction of high-resolution ultrasound. Miniaturisation revived fetoscopy in the 1990 s, since when it has been successfully used to operate on the placenta and umbilical cord. Today, it is also used in fetuses with congenital diaphragmatic hernia (CDH), in whom lung growth is triggered by percutaneous tracheal occlusion. It can also be used to diagnose and treat urinary obstruction. Many fetal interventions remain investigational but for a number of conditions randomised trials have established the role of in utero surgery, making fetal surgery a clinical reality in a number of fetal therapy programmes. The safety of fetal surgery is such that even non-lethal conditions, such as myelomeningocoele repair, are at this moment considered a potential indication. This, as well as fetal intervention for CDH, is currently being investigated in randomised trials.