Tracheobronchial tree, stenosis or obstruction Interventional procedures, complications Balloon dilation

A male infant

A male infant weighting 2140g was born at 35 weeks' gestation. The Apgar scores were 9 at one minute and 10 at five minutes. The baby was discharged after one week but he had dyspnea and severe cyanosis when he criedand was transferred to our hospital at 29 days of age. He had a systolic murmur on physical examinations, but also had clear breath sounds. Echocardiography at our hospital showed a large ventricular septal defect, aortopulmonary window and left sided SVC. He underwent total repair of the aorto-pulmonary window and right upper lobectomy at 36 and 42 days of age, respectively. At that time, cardiac problems and right upper lobar tracheal bronchus were mainly responsible for his respiratory problem, and the surgeons thought that the patient would not tolerate combined tracheal repair and aorto-pulmonary window repair or right upper lobectomy. However, there was no improvement in the dyspnea or CO2 retention and he could not be weaned from the ventilation after surgery. Bronchoscopy confirmed tracheal stenosis from complete cartilaginous rings in the lower trachea. At 61 days of age, the patient underwent balloon tracheoplasty under sedation in order to split and dilate the stenotic tracheal lumen. After balloon tracheoplasty, the ventilation setting improved, however, it was stationary after three days following the procedure. Therefore, temporary stent placement for six months was performed to allow tissue healing around the torn tracheal wall. After stent implantation, the patient's condition was improved and he had a stable ventilation setting.Five months after stent implantation, he had several episodes of pneumonia and culture of the endotracheal tube showed colonization of multiple bacteria. We thought that the stent would be an infection source and so removed it under bronchoscopic control.Although there was mild granulation tissue at both ends of the stent on bronchoscopy, the tracheobronchial lumen was completely patent. The stent was easily removed by pulling a retrievable lasso with bronchoscopic biopsy forcep. Seven weeks after stent removal, extubation was successfully achieved. He was transferred to a general ward two months after stent removal and was discharged one month later.

congenital tracheal stenosis

Heart CT examinations, including two-dimensional (2D) - and three-dimensional (3D) - reconstruction airway images showed right upper lobar tracheal bronchus (the abnormal upper lobar bronchus originating from the trachea superior to its bifurcation) and a 13-mm segment of narrowing in the lower trachea (Fig. 1a). The diameter of the narrowed segment in the lower trachea was 3.5 mm, while that of the normal segment in the upper trachea was 6.5 mm. Emphysematous change was seen in the right upper lobe due to the air-trapping by the tracheal bronchus and mild collapse of the right middle and lower lobes on plain radiography (not shown). Follow-up CT images obtained three and 12 months after stent removal showed a widened lumen of the lower trachea (Fig 3).

A. Three-dimensional (3D) reconstruction CT image, anteroposterior view, shows 13-mm segment of severe narrowing (arrows) of the lower trachea from below the tracheal bronchus (arrowhead) to the carina. B. Formation of the waist is seen initially. A surgical clip after right upper lobectomy is seen. (b) Formation of the waist is seen initially. A surgical clip after right upper lobectomy is seen. C. Suddenly, the balloon dilates to its full diameter (6 mm) with an explosive sound.

A. The stent is flared distally to fit into the carina. The retrieval lasso (arrow) is attached to the upper inner margin of the stent for bronchoscopic removal of the stent. B. The stent is deployed as the sheath (arrows) is slowly withdrawn with one hand while the pusher catheter is held in place with the other hand. Stent placement was performed through the endotracheal tube (arrowhead). C. The stent is nearly fully dilated immediately following balloon dilation (not shown).

Three-dimensional reconstruction CT image obtained 12 months after stent removal, anteroposterior view, shows a widened lumen (arrows) of the lower trachea. The diameter of the dilated lumen is 7 mm.

Balloon tracheoplasty technique : A 6-mm (diameter) 2-cm (length) ballooncatheter (Cordis, Roden, the Netherlands) was advanced through the endotracheal tube (3.5 mm [inner diameter] - 10 cm [length]) and dilated the stenotic lumen up to the maximum pressure of 5 ATM. Initially, waist formation of the inflated balloon was noted and then the waist disappeared with an explosive sound (Fig 1b, 1c). There was no change of vital signs during and after balloon dilation. Post-procedure bronchoscopy showed disruption of the complete cartilaginous ring at the posterior aspect of the trachea minimal bleeding was also observed, however, there was no air leakage. Stent placement technique: An 8-mm (diameter) 2 cm (length) polyurethane-covered retrievable self-expandable metallic stent with the retrieval lasso attached to the proximal end of the stent was used (Fig 2a). The stent was woven from a single thread of nitinol wire in a tubular configuration and the distal portion was flared distally to fit into the carina. Then, the stent was covered by using a dipping method with a 12% polyurethane solution. The stent and introducer set were constructed according to our specifications by a local manufacturer (Taewoong, Seoul, Korea). One week following balloon tracheoplasty, a 9-Fr sheath with a dilator was passed under fluoroscopic guidance over the guidewire into the trachea through the endotracheal tube (3.5mm, 10cm) and was advanced until the distal tip of the sheath reached the carina. Then the dilator and the guide wire were removed from the sheath. After that, a stent was compressed and loaded into the sheath and then positioned to cover the stenotic airway (Fig 2b). Immediately after the procedure, the stent was not fully dilated and the right lung began to collapse. We dilated the stent and both main bronchi using a 6 mm-diameter balloon catheter. We performed balloon dilation using 6 mm-diameter balloon catheter alternately in the right and left main bronchus with the proximal portion of the balloon within the stent. After balloon dilation, the stent was nearly fully dilated and the right lung was aerated (Fig 2c). Stent placement was also performed under sedation.

Infants born with congenital tracheal stenosis from complete cartilaginous rings often have respiratory distress which may be seen in isolation or in conjunction with other respiratory tract or cardiac anomalies (1,2). Since the early-1990s, posterior tracheal splitting by balloon dilation with or without assistance of temporary placement of an endotracheal tube,has been reported to be successful formaintaining the desirable lumen by Bag well et al. and Messineo et al. (3.4). Their trial was based on the hypothesis that as the cartilaginous rings have a weak point in the posterior wall, aggressive balloon dilation would result in a posterior longitudinal splitting of the trachea and fibrous tissue could cover the split area a few weeks after placement of an endotracheal tube (3). However, keeping an endotracheal tube would be very annoying and difficult to maintain without sedation for an infant or child. Recently, the uncovered metallic stents used in the vascular system have also been used in congenital tracheobronchial stenoses caused by cartilaginous rings (5-7). However, uncovered metallic stents have possible long-term risks of restenosis by recurrent granulation tissue with difficult or impossible removal, failure of tracheal growth with age, and tracheal erosion or penetration to the great vessels (5-7). We initially planned to treat the patient with only rupture of the complete cartilaginous rings by balloon dilation because we agreed to the assertion by Bag well et al. that disruption of the cartilaginousrings represents a prerequisite step for increase in the luminal diameter itself (4). This balloon posterior tracheal splitting carries the potential risks of free perforation of the trachea although the change to disastrous mediastinitis requiring surgical management has not been reported. In this patient, the widened tracheal lumen by balloon posterior tracheal splitting was not enough to maintain the functional patency of the lumen. We presumed that the free-flap-like, torn tracheal lumen probably caused disturbance of airflow, especially on expiration,as tissue healing around the splitting was delayed. Therefore, temporary placement of a covered retrievable self-expandable metallic stent was chosento allow tissue healing to create new fibrous tracheal wall around the tear. A covered retrievable self-expandable metallicstent is very useful in that it can prevent the growth of granulation tissue through the stent wires and erosion or penetration of the stent to surrounding tissue in case of stent fracture. Moreover, the stent can easily be removed easily with bronchoscopic or interventional procedures after a given period of time, therefore, it can prevent complications associated with long-term stent placement, such as granulation tissue or infection around the stent and difficult stent exchange after increase of the tracheal diameter due to the normal growth of the infant. However,it is very difficult to determine the optimal time to remove a stent as the length and severity of the tear differ from patient to patient. We think that six months is enough for tissue to heal around the stent before encountering significant stent-related complications such as granulation tissue formation (8).

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