Congenital tracheobronchial stenosis.

Congenital tracheobronchial stenosis is a rare disease characterized by complete tracheal rings that can affect variable lengths of the tracheobronchial tree. It causes high levels of morbidity and mortality both due to the stenosis itself and to the high incidence of other associated congenital malformations. Successful management of this complex condition requires a highly individualized approach delivered by an experienced multidisciplinary team, which is best delivered within centralized units with the necessary diverse expertise. In such settings, surgical correction by slide tracheoplasty has become increasingly successful over the past 2 decades such that long-term survival now exceeds 88%, with normalization of quality of life scores for patients with non-syndrome-associated congenital tracheal stenosis. Careful assessment and planning of treatment strategies is of paramount importance for both successful management and the provision of patients and carers with accurate and realistic treatment counseling.

Liver-to-thoracic volume ratio: use at MR imaging to predict postnatal survival in fetuses with isolated congenital diaphragmatic hernia with or without prenatal tracheal occlusion.

OBJECTIVE: To evaluate the relationship of the liver-to-thoracic volume ratio (LiTR) by MRI with postnatal survival in foetuses with isolated congenital diaphragmatic hernia (CDH). METHODS: In 30 conservatively managed CDH foetuses and in 31 who underwent fetoscopic endoluminal tracheal occlusion (FETO), logistic regression analysis was used to investigate the effect on postnatal survival of the observed-to-expected (O/E) ratio of total foetal lung volume (TFLV), LiTR, gestational age at delivery, CDH side, intrathoracic position of the liver and, for those who underwent FETO, gestational age at FETO and occlusion period. For 19 foetuses undergoing FETO, a post-FETO MRI was available. The proportionate increase in O/E ratio of TFLV at 3-8 weeks after FETO was compared with the pre-FETO value and correlated with pre-FETO LiTR using linear regression analysis. RESULTS: For conservatively managed foetuses, only LiTR provided a significant prediction of postnatal survival. For foetuses undergoing FETO, LiTR and gestational age at delivery provided a significant independent prediction of postnatal survival. There was a significant inverse association between lung response and pre-FETO LiTR. CONCLUSION: In foetuses with CDH with/without FETO treatment, the LiTR is predictive of postnatal survival at discharge. In foetuses treated with FETO, LiTR is predictive of post-FETO lung response. KEY POINTS: • Congenital diaphragmatic hernia is usually managed conservatively before surgery soon after delivery • Fetoscopic endoluminal tracheal occlusion (FETO) has been introduced for severely affected foetuses • In conservatively managed CDH, the liver-to-thoracic volume ratio (LiTR) predicted postnatal survival best. • In severe CDH with prenatal FETO, LiTR also helped predict postnatal survival. • LiTR should be integrated into the prenatal decision-making for foetuses with CDH.

Prenatal diagnosis of fetal left pulmonary artery sling.

Left pulmonary artery (LPA) sling is a very rare anomaly in which the LPA arises distally, far from the right pulmonary artery on the right side of the distal trachea, turns sharply leftwards around the trachea and courses to the left lung hilum through the space between the trachea and esophagus. LPA sling is often associated with distal tracheal narrowing, due to either intrinsic stenosis or secondary compression by the anomaly itself. To our knowledge, prenatal diagnosis of LPA sling has not been reported so far. We report a case in which LPA sling was diagnosed during fetal ultrasound examination.

Fetal tracheolaryngeal airway obstruction: prenatal evaluation by sonography and MRI.

We reviewed the sonographic and MRI findings of tracheolaryngeal obstruction in the fetus. Conditions that can cause tracheolaryngeal obstruction include extrinsic causes such as lymphatic malformation, cervical teratoma and vascular rings and intrinsic causes such as congenital high airway obstruction syndrome (CHAOS). Accurate distinction of these conditions by sonography or MRI can help facilitate parental counseling and management, including the decision to utilize the ex utero intrapartum treatment (EXIT) procedure.

The effect of maternal betamethasone and fetal tracheal occlusion on pulmonary vascular morphometry in fetal rabbits with surgically induced diaphragmatic hernia: a placebo controlled morphologic study.

OBJECTIVES: We studied the vascular effects of betamethasone (BM) and/or tracheal occlusion (TO) in fetal rabbits with surgically induced congenital diaphragmatic hernia (CDH). METHODS: At day 23 (pseudoglandular phase; term = 31 d), 54 ovarian-end fetuses from 27 does underwent induction of CDH. Thirteen did receive either 0.05 mg/kg BM, on days 28 and 29 with a 24-h interval, or 14 saline [controls (CTR)]. At day 28, one ovarian-end fetus underwent TO and harvesting was at term. In total, we compared (ANOVA) lung-to-body weight ratio (LBWR) and vascular morphometric indices in survivors from the following groups (n - number alive at delivery): CDH (9); CDH + TO (10); unoperated controls (14); CDH + BM (10); CDH + TO (9); controls CTR + BM (13). RESULTS: Maternal BM had no effect on LBWR. LBWR was comparable to normal in CDH fetuses undergoing TO. Both TO and BM have an effect on medial thickening due to CDH which is larger when both interventions are combined. CONCLUSIONS: Both TO and BM lessen peripheric muscularization present in CDH lungs and their effect is cumulative.

Pulmonary arteriole muscularization in lambs with diaphragmatic hernia after combined tracheal occlusion/glucocorticoid therapy.

OBJECTIVE: A morphometric study was performed to examine the effects of prenatal glucocorticoids, which were administered 48 hours before birth, on muscularization of small pulmonary arterioles (<60 microm diameter) in lambs with diaphragmatic hernia (DH) after fetal tracheal occlusion (TO). STUDY DESIGN: DH was created in 23 fetal sheep at 65 days gestation. TO was performed in 16 of 24 fetuses between 110 and 140 days of gestation; 9 of the fetuses were exposed prenatally to betamethasone (0.5 mg/kg body weight) 48 hours before delivery. Six sham-operated animals served as controls. Sections of paraffin that were embedded in lung tissues were stained with Elastin-Van Gieson, and the percentage of medial wall thickness (MWT) was determined. RESULTS: The percentage of MWT in DH lambs (29.6% +/- 1.9%) was increased compared with sham animals (18.1% +/- 1.3%) and was not different from that of DH/TO animals (30.3% +/- 1.7%). In DH/TO + glucocorticoid lambs, the percentage of MWT (24.6% +/- 1.2%) was significantly lower than in the DH/TO group but was higher than the sham group. CONCLUSION: In fetuses who underwent prolonged TO therapy for severe DH, prenatal glucocorticoid treatment decreased medial hypertrophy of pulmonary arterioles by approximately 19%. We speculate that such structural changes may have contributed to improve gas exchange that was observed in this model.

Tracheal occlusion: a review of obstructing fetal lungs to make them grow and mature.

Fetal lung growth and functional differentiation are affected strongly by the extent that pulmonary tissue is distended (expanded) by liquid that naturally fills developing future airspaces. Methods that prevent normal egress of this lung fluid through the trachea magnify mechanical stretching of lung parenchymal cells, thereby promoting lung development. Indeed, experimental observations demonstrate that in utero tracheal occlusion (TO) performed on fetuses during the late canalicular-early saccular stage potently stimulates pulmonary growth and maturation. In this review, we present the four principle non-human animal models of TO/obstruction and discuss them in relation to their utility in elucidating lung development, in remedying congenital diaphragmatic hernia (CDH) as well as in investigating the stretching effects on growth and remodeling of the fine vasculature.

Expression of apoptosis-related genes after fetal tracheal occlusion in rabbits.

BACKGROUND/PURPOSE: Late-gestation lung remodeling is associated with alveolar type II cell apoptosis early in the saccular stage (day 28 in fetal rabbits). Intrauterine tracheal occlusion (TO), a potent stimulus of fetal lung growth and maturation, significantly increases type II cell apoptosis. The aim of this study was to determine the effect of fetal TO on the spatiotemporal expression of key apoptosis-related signaling molecules. METHODS: Tracheal occlusion of fetal rabbits was performed at gestational day 25 (term, 31 days), and apoptotic gene expression was studied between days 26 and 28. RESULTS: At days 26 and 27, the protein levels of Fas and Fas-ligand (FasL) in lung lysates were similar in TO fetuses and sham-operated controls. At day 28, however, synchronous with the onset of TO-induced pulmonary distension and type II cell apoptosis, the FasL protein content was 8-fold higher in TO lungs compared with controls (P < .01), whereas Fas levels were comparable. In contrast, Bax and Bcl-2 protein levels were similar in TO and control fetuses at all time-points. TO significantly increased the cellular concentration of immunoreactive FasL in type II cells and bronchial epithelial Clara cells. Furthermore, bronchoalveolar lavage fluid (BAL) from TO fetuses at day 28 induced significantly more type II cell apoptosis in vitro compared with control BAL, an effect that was inhibited by neutralizing anti-FasL antibody. CONCLUSIONS: Our findings show that TO results in time-specific increase of both cellular and soluble FasL in fetal lungs and implicate the Fas/FasL pathway as a pivotal autocrine and/or paracrine regulator of TO- induced type II cell apoptosis.

Lung function in lambs with diaphragmatic hernia after reversible fetal tracheal occlusion.

BACKGROUND/PURPOSE: Short-duration resuscitation (< or =4 hours) of lambs with diaphragmatic hernia treated in utero with tracheal occlusion have shown improved lung function compared with untreated diaphragmatic hernia. This may be a transient phenomenon in the treated diaphragmatic hernia lambs because of surfactant deficiency. Our objective was to analyze the effect of fetal tracheal occlusion with or without release of the occlusion 1 week before delivery on pulmonary function during a longer period of resuscitation (8 hours) in the diaphragmatic hernia lamb model. METHODS: Four groups were compared: diaphragmatic hernia (n = 5), diaphragmatic hernia and tracheal occlusion until delivery (n = 5), diaphragmatic hernia and tracheal occlusion with release of the occlusion 1 week before delivery (n = 5), and normal controls (n = 4). RESULTS: Despite persistently decreased surfactant levels, diaphragmatic hernia lambs treated with tracheal occlusion had normal-sized lungs with marked improvement in lung function and gas exchange over 8 hours when compared with untreated lambs with diaphragmatic hernia. Release of the tracheal occlusion 1 week before delivery added no benefit. CONCLUSIONS: It appears that surfactant-independent mechanisms such as pulmonary growth and structural changes are of foremost importance in relating to improved compliance, oxygenation, and ventilation of diaphragmatic hernia lambs treated with tracheal occlusion.

Bronchopulmonary foregut malformations: embryology, radiology and quandary.

Bronchopulmonary foregut malformations (BPFM) are a heterogeneous group of pulmonary developmental anomalies that present at varying ages and with overlapping symptoms, signs and radiology. This article discusses the embryology of these lesions with reference to possible common origins and the link between aetiology and radiological appearance. The radiology of each lesion, both antenatally and postnatally, is described and illustrated. A number of quandaries exist in the prediction of prognosis and subsequent treatment of BPFM. We discuss the radiological features that may help to elucidate an individual prognosis and aid in the planning of treatment. The treatment options available for BPFM are briefly discussed. Finally, the link between BPFM, in particular cystic adenomatoid malformations and malignancy, is discussed. We aim to provide a comprehensive overview of the embryology, radiology, prognosis and treatment highlighting contentious issues of BPFM.

Alterations in lung expansion affect surfactant protein A, B, and C mRNA levels in fetal sheep.

Obstruction of the fetal trachea is a potent stimulus for fetal lung growth, and it has been suggested that this procedure may be used therapeutically to reverse lung growth deficits in human fetuses with lung hypoplasia. However, little is known about the effects of increased lung expansion on other aspects of lung development. Our aim was to determine the effect of increased and decreased lung expansion on the mRNA levels encoding surfactant protein (SP) A, SP-B, and SP-C in ovine fetal lungs. Lung tissue samples were collected from fetuses exposed to 2, 4, or 10 days of increased lung expansion caused by tracheal obstruction. The mRNA levels for SP-A, SP-B, and SP-C were determined by Northern blot analysis with specific ovine cDNA probes; SP-A protein levels were determined by Western blot analysis. Compared with age-matched (128-day gestational age) control fetuses, SP-A, SP-B, and SP-C mRNA levels in fetal lung tissue were significantly reduced at 2 days of tracheal obstruction and remained reduced at 4 and 10 days. However, SP-A protein levels were not reduced at 2 days of tracheal obstruction, tended to be reduced at 4 days, and were almost undetectable at 10 days. In contrast to tracheal obstruction, 7 days of lung liquid drainage significantly increased SP-C, but not SP-A, mRNA levels in fetal lung tissue compared with age-matched control fetuses. Our results demonstrate that increases in fetal lung expansion, induced by obstruction of the fetal trachea, cause large simultaneous reductions in SP-A, SP-B, and SP-C mRNA levels in the fetal lung as well as a decrease in SP-A protein levels. These data suggest that expression of the genes encoding SPs in the fetal lung are specifically responsive to the degree of lung expansion.

The near complete tracheal ring deformity.

Congenital complete and near-complete tracheal rings are extremely rare tracheal deformities. There are fewer than 100 cases of congenital complete tracheal rings, and only four cases of near-complete described in the literature. Long-segment occurrences of these anomalies are usually incompatible with life. We describe the presentation of the long-segment near complete tracheal ring deformity and long-segment anterior fusion of cartilage rings (cartilage sleeve deformity) in a living infant. The literature is reviewed, and the embryology, presentation, and management of these extremely rare anomalies are discussed.

In utero lung growth of fetal sheep with diaphragmatic hernia and tracheal stenosis.

The observation that tracheal ligation produces pulmonary hyperplasia even in animals with surgically induced diaphragmatic hernia (DH) has led to rapid application of the technique to human fetuses with DH. The aim of this study was to determine how rapidly fetal lung volume increases after creation of a high-grade tracheal stenosis in fetal sheep with surgically created DH. Twenty-three fetal sheep were prepared with a left thoracotomy at 90 days' gestational. Six had creation of a DH with tracheal stenosis (DHTS) over an 18-gauge cannula, which was then removed. Ten had DH alone, and seven control animals (CT) had a thoracotomy without DH. Thirty days later, vascular and tracheal loop catheters were inserted in all animals and tunneled out the ewes' flank. Between 125 and 140 days' gestation, lung volumes and lung liquid production were measured in awake, unanesthetized animals using a standard double-marker dilution technique. Average lung volumes (in milliliters) were 150.9 +/- 13.9 for CT, 29.3 +/- 4.4 for DH, and 414.5 +/- 88 for DHTS (p < 0.01). Mean lung liquid production varied from 6.00 +/- 2.23 mL/h in DH animals before 130 days to 16.69 +/- 8.29 mL/h in DHTS animals after 135 days' gestation. DH animals had lower lung liquid production (8.51 +/- 1.4 mL/h) than CT (12.4 +/- 0.8 mL/h) or DHTS animals (12.4 +/- 2.2 mL/h)(P < .01). The rate constant gamma (h-1) for lung liquid production was significantly higher in DH animals than in either CT or DHTS animals (P < .01). Tracheal stenosis in this model causes rapid lung growth before 130 days' gestation. The authors speculate that short periods of incomplete stenosis might reverse the pulmonary hypoplasia associated with DH. To achieve this goal, the timing and duration of treatment and the optimal degree of stenosis must be defined.

[Right aortic arch simulates mediastinal tumor: diagnosis with spiral CT]. / Rechtsverlaufender Aortenbogen täuscht Mediastinaltumor vor: Diagnose mittels Spiral-CT.

We report the case of a patient with right aortic arch (type III) mimicking a mediastinal tumor. We discuss the radiological findings together with their embryologic correlations, and emphasize the role of spiral-CT in the acquisition of imaging data under difficult diagnostic conditions.