Surgical reconstruction for congenital tracheal malformation and pulmonary artery sling

Impact of Tracheal Arborization and Lung Hypoplasia in Repair of Pulmonary Artery Sling in Combination With Long-Segment Tracheal Stenosis

Background: Reimplantation of the left pulmonary artery (LPA) and slide tracheoplasty has been our standard approach of care for patients with pulmonary artery sling (PAS) and tracheal stenosis. We present our experience, with emphasis on tracheal arborization and hypoplastic lungs; and their impact on long-term outcome of children with PAS and tracheal stenosis. Methods: It is a retrospective comparative study. Data were classified and analyzed based on the type of tracheobronchial arborization and normal versus hypoplastic lungs. Results: Seventy-five children operated between January 1994 and December 2019 (67 with normal lungs and 8 with lung hypoplasia/agenesis) were included. Patients with hypoplastic lungs had higher rates of preoperative ventilation (87.5%), postoperative ventilation (10 vs 8 days, P = .621), and mortality (50% vs 9%, P = .009) compared with those with normal lungs. Nineteen patients had tracheal bronchus (TB) variety and 30 patients had congenital long-segment tracheal stenosis (CLSTS) variety of tracheobronchial arborization. Endoscopic intervention was needed in 47.4% of patients with TB type and 60% with CLSTS type. CLSTS patients had higher rates of preoperative ventilation (60% vs 47.4%, P = .386), longer periods of postoperative ventilation (13 vs 6.5 days, P = .006), and ICU stay (15 vs 11 days, P = .714) compared with TB type. Conclusion: Surgical repair of PAS with tracheal stenosis has good long-term outcomes. All variations of tracheal anatomy can be managed with slide tracheoplasty. Persistence of airway problems requires intervention during follow-up as tracheal stenosis continues to be the Achilles heel.

Pulmonary artery sling: An overview

Pulmonary artery sling is a rare childhood vascular tracheobronchial compression syndrome that is frequently associated with tracheal stenosis. Consequently, neonates or infants may present with critical airway obstruction if there is long segment airway narrowing and complete rings. Rapid diagnosis of this cardiac vascular malformation and evaluation of the extent and severity of airway involvement is essential to plan surgery, typically a slide tracheoplasty to relieve critical airway obstruction. Long term outcome can be excellent following surgical repair of the stenosed airway and reimplantation of the left pulmonary artery. In this review we focus on the embryology, diagnostic workup, airway investigations and management for this rare but challenging congenital condition.

A Delayed Anatomic Diagnosis and Management Challenge in an Initially Asymptomatic Infant With Type II Pulmonary Artery Sling: A Case Report

Pulmonary artery sling (PAS) is a rare but fatal malformation. Patients with PAS tend to develop obstructive symptoms in few weeks of life. Conversely, some patients may be otherwise mild or asymptomatic in their early life. Currently, no consensus on the intervention timing and treatment strategy for asymptomatic and mild cases has been reached. Moreover, the extent of tracheal stenosis is another determining factor for the choice of intervention timing since clinical symptoms might not correspond well with the degree of stenosis. Lack of comprehensive assessment of entire airways confer underestimation of disease severity and in turn improper choice of treatment regimens and poor outcomes. Herein, we described an infantile case of PAS, who was scheduled initially for periodic outpatient follow-up on account of the absence of symptoms and inadequate imaging assessment at diagnosis. The patient developed recurrent wheezing and progressive respiratory distress at 7 months of age. After left pulmonary artery (LPA) reimplantation without tracheal intervention, bronchoscopy was performed due to failure to wean from mechanical ventilation, which demonstrated complete tracheal cartilage rings, a long segment tracheal stenosis, a low tracheal bifurcation at T6, and the absence of a separate right middle lobe bronchus. The patient was finally diagnosed with type IIb PAS and extubated successfully following conservative treatment. Miserably, neurological sequelae were devastating, leading to poor outcomes. Comprehensive airway evaluation using bronchoscopy is substantial to early identification of all components responsible for airway compromise in PAS anatomic subtypes. Considering severe concomitant maldevelopment of the bronchial tree in children with type IIb PAS, early and complete correction by surgery might decrease perioperative morbidities and mortalities of these patients.

Evaluating Feasibility of Human Tissue Engineered Respiratory Epithelium Construct as a Potential Model for Tracheal Mucosal Reconstruction

The normal function of the airway epithelium is vital for the host’s well-being. Conditions that might compromise the structure and functionality of the airway epithelium include congenital tracheal anomalies, infection, trauma and post-intubation injuries. Recently, the onset of COVID-19 and its complications in managing respiratory failure further intensified the need for tracheal tissue replacement. Thus far, plenty of naturally derived, synthetic or allogeneic materials have been studied for their applicability in tracheal tissue replacement. However, a reliable tracheal replacement material is missing. Therefore, this study used a tissue engineering approach for constructing tracheal tissue. Human respiratory epithelial cells (RECs) were isolated from nasal turbinate, and the cells were incorporated into a calcium chloride-polymerized human blood plasma to form a human tissue respiratory epithelial construct (HTREC). The quality of HTREC in vitro, focusing on the cellular proliferation, differentiation and distribution of the RECs, was examined using histological, gene expression and immunocytochemical analysis. Histological analysis showed a homogenous distribution of RECs within the HTREC, with increased proliferation of the residing RECs within 4 days of investigation. Gene expression analysis revealed a significant increase (p < 0.05) in gene expression level of proliferative and respiratory epithelial-specific markers Ki67 and MUC5B, respectively, within 4 days of investigation. Immunohistochemical analysis also confirmed the expression of Ki67 and MUC5AC markers in residing RECs within the HTREC. The findings show that calcium chloride-polymerized human blood plasma is a suitable material, which supports viability, proliferation and mucin secreting phenotype of RECs, and this suggests that HTREC can be a potential candidate for respiratory epithelial tissue reconstruction.

Converging 3D Printing and Electrospinning: Effect of Poly(l-lactide)/Gelatin Based Short Nanofibers Aerogels on Tracheal Regeneration

Recently, various tissue engineering based strategies have been pursued for the regeneration of tracheal tissues. However, previously developed tracheal scaffolds do not accurately mimic the microstructure and mechanical behavior of the native trachea, which restrict their clinical translation. Here, tracheal scaffolds are fabricated by using 3D printing and short nanofibers (SF) dispersion of poly(l-lactide)/gelatin (0.5-1.5 wt%) to afford tracheal constructs. The results display that the scaffolds containing 1.0 wt % of SF exhibit low density, good water absorption capacity, reasonable degradation rate, and stable mechanical properties, which were comparable to the native trachea. Moreover, the designed scaffolds possess good biocompatibility and promote the growth and infiltration of chondrocytes in vitro. The biocompatibility of tracheal scaffolds is further assessed after subcutaneous implantation in mice for up to 4 and 8 weeks. Histological assessment of tracheal constructs explanted at week 4 shows that scaffolds can maintain their structural integrity and support the formation of neo-vessels. Furthermore, cell-scaffold constructs gradually form cartilage-like tissues, which mature with time. Collectively, these engineered tracheal scaffolds not only possess appropriate mechanical properties to afford a stabilized structure but also a biomimetic extracellular matrix-like structure to accomplish tissue regeneration, which may have broad implications for tracheal regeneration.

Relationship between a Tracheal and Left Pulmonary Artery Stenosis Index and the Prognosis of Pulmonary Artery Sling with Tracheal Stenosis

Pulmonary artery sling is a rare congenital pulmonary vascular malformation, often associated with tracheal or bronchial stenosis. Surgical treatment of pulmonary artery sling with tracheal stenosis (T) has a high risk of death and a relatively poor prognosis. This study explored the relationship between the T and left pulmonary artery stenosis (P) ratio and the effects of surgery for pulmonary artery sling with tracheal stenosis. Patients undergoing surgery for pulmonary artery sling in our center from January 2010 to December 2018 were retrospectively analyzed. Routine cardiac-enhanced computed tomography (CT) was performed preoperatively, and the P and T diameters were measured on the CT image. The T/P ratio was then calculated and analyzed. Thirty cases of pulmonary artery sling combined with tracheal stenosis were operated under cardiopulmonary bypass. The mean age at operation was 13.8 ± 13.6 months (1.2-57.1 months, Q1-Q3: 5-17 months), and the mean body weight was 8.8 ± 3.5 kg (3.8-17.3 kg, Q1-Q3: 5.8-11.5 kg). Twenty-three patients survived, and seven died, with an overall survival rate of 76.7%. Twenty-four patients underwent left pulmonary artery re-implantation, six patients underwent simultaneous left pulmonary artery re-implantation and slide tracheoplasty, and patients with intracardiac malformations (ventricular septal defect (n = 6) and atrial septal defect (n = 4)) underwent concurrent repair of the intracardiac defect. All cases had different degrees of tracheal stenosis, and the most narrowed trachea occurred with compression by the left pulmonary artery sling. The T/P ratio in the tracheoplasty group was significantly higher than that in the non-tracheoplasty group. The mortality rate in the T/P ≤ 1.15 group was significantly lower than that in the T/P > 1.15 group. Pulmonary artery sling treatment has a high risk of death. Left pulmonary artery re-implantation is an effective and safe surgical method for treating pulmonary artery sling, and slide tracheoplasty is an effective surgical method to correct tracheal stenosis. Children with T > 78.4% should receive active intervention for the tracheal stenosis, and these children have a considerable postoperative survival rate. The T/P ratio can be used to compare the relative superiority of the two compressions. A T/P ratio > 1.15 can be used as a reference index for intervention in tracheal stenosis and is a risk factor for postoperative death.

Surgical repair for post-tuberculosis tracheobronchial stenosis

AIM

Post-tuberculosis tracheobronchial stenosis is rare but one of the most dangerous complications of tracheobronchial tuberculosis. Balloon dilatation, stent insertion, laser photoresection, argon plasma coagulation, and cryotherapy are some of the initial treatments recommended for mild to moderate cases. Here, we report a case series of patients who underwent segmental resection and end-to-end anastomosis for bronchial stenosis and a sliding technique for severe and long-segment tracheal stenosis.

METHODS

We retrospectively reviewed the medical records of patients with post-tuberculosis tracheobronchial stenosis operated on in our thoracic surgery department. Of the 7 cases that were treated, two had severe tracheal stenosis stretching over 50% of the tracheal length, one was operated on using resection and end-to-end anastomosis, and the other had sliding tracheoplasty. The other 5 cases of bronchial stem stenosis were treated with segmental resection and end-to-end anastomosis.

RESULTS

All five patients with bronchial stenosis had a good outcome; the ipsilateral lung was well ventilated and respiratory function was good. One patient with tracheal stenosis, treated with segmental resection and end-to-end anastomosis, died after the surgery, and the other patient, treated with slide tracheoplasty, had a good recovery.

CONCLUSION

The treatment plan for patients with post-tuberculosis tracheobronchial stenosis should be on a patient-by-patient basis. Sliding tracheoplasty can be a treatment option in patients with long-segment tracheal stenosis.

Effect of resected length in reconstructive surgery for tracheobronchial injury

Background

Mechanical injury to the trachea and bronchi may cause mild to severe stenosis requiring surgical intervention for reconstructing the damaged trachea. The location, length, and cause of injury are important factors affecting the surgical outcome.

Method

We conducted a retrospective study to evaluate the results of reconstructive surgery on noncancerous tracheobronchial lesions in 75 patients aged 5–55 years who had undergone reconstructive tracheobronchial surgery in our hospital from 2009 to 2018.

Results

The causes of tracheobronchial injury included blunt trauma in 38 patients, sharp penetrating trauma in 24, a postintubation lesion in 6, a post-tracheotomy lesion in 3, tuberculosis in 3, and an adult congenital lesion in one. In 59 cases of a lesion in the trachea, the length of missing segment before reconnection was 1–2 cm in 6 cases, 3 cm in 22, 4 cm in 18, 5 cm in 13, and >5.5 cm in 1 case. The length of the resected segment was <5.5 cm in all survivors, whereas one death occurred when the resected length was approximately 6 cm.

Conclusions

The length of the resected segment and precision of the surgery are crucial for determining the outcome of surgery.