Tracheobronchial Issues in Congenital Heart Disease Catherine K. Hart,a,b and Michael J. Ruttera,b In children with congenital heart disease, tracheobronchial compromise is uncommon but potentially life-threatening. Airway lesions in these patients may be congenital or acquired, and may be stenotic, compressive, or malacic in nature. We present an overview of the etiologies of tracheobronchial lesions typically seen in children with congenital heart disease and review management options for these lesions. Semin Thorac Cardiovasc Surg Pediatr Card Surg Ann 18:57-61 C 2015 Elsevier Inc. All rights reserved.
Congenital Tracheal Stenosis Complete Tracheal Rings
lthough complete tracheal rings (CTRs) are rare, they are the most common cause of congenital tracheal stenosis. The degree of stenosis may vary from mild to severe; however, the diameter of the complete cartilage rings is always smaller than the trachea above the affected segment. A number of recognizable morphologic CTR patterns exist; of these patterns, the most commonly seen are: 1) CTRs that are of reasonable size proximally, but cone down to a small distal ring close to the carina; 2) the “stovepipe” airway with a long segment of CTRs of similar diameter; 3) a short-segment stenosis, which often occurs in the midtrachea; and 4) CTRs associated with a high tracheal (or pig) bronchus.1
Greater than 75% of patients also have other, often severe, congenital anomalies. Infants with concomitant complete bronchial rings and those with a hypoplastic or atretic lung are among the most challenging to manage. According to our previously published ﬁndings,2 60% of patients with CTRs had cardiovascular abnormalities, notably 21% have a pulmonary artery sling (PAS). Commonly associated cardiac a
Division of Pediatric Otolaryngology–Head and Neck Surgery, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH. b Department of Otolaryngology–Head and Neck Surgery, University of Cincinnati College of Medicine, Cincinnati, OH. Address correspondence to Michael J. Rutter, MBChB, FRACS, Division of Pediatric Otolaryngology–Head and Neck Surgery, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH 45229-3039. E-mail: [email protected]
http://dx.doi.org/10.1053/j.pcsu.2014.12.001 1092-9126/& 2015 Elsevier Inc. All rights reserved.
anomalies include atrioventricular canal defects, atrial septal defects, ventricular septal defects, tetralogy of Fallot, and total anomalous pulmonary venous return. Twenty percent of infants with CTRs also have Down syndrome. Children typically present with progressive worsening of respiratory function over the ﬁrst few months of life. Stridor, retractions, dying spells, and marked exacerbation of symptoms during intercurrent upper respiratory tract infections are generally seen. Children with distal tracheal stenosis usually exhibit a characteristic biphasic wet-sounding breathing pattern that transiently clears with coughing. This pattern is referred to as “washing machine breathing.” Because the growth of the trachea is not commensurate with the growth of the child over the ﬁrst few months of life, decompensation frequently occurs around 4 months of age, with the child presenting in respiratory failure. Although the initial evaluation should include plain airway ﬁlms, deﬁnitive assessment requires rigid bronchoscopy. To facilitate bronchoscopy, good communication with anesthesiologists is essential. We prefer that the child is spontaneously ventilating, utilizing both sevoﬂurane and propofol. A single dose of dexamethasone (0.5 mg/kg) is administered on induction to minimize airway edema. The trachea is then suctioned with a soft 6 French catheter and the patient is preoxygenated. Next, an additional propofol bolus is delivered to temporarily halt respiratory efforts during the bronchoscopy. Ideally, the aims of endoscopic evaluation are to conﬁrm the diagnosis of tracheal stenosis, establish whether this is caused by CTRs, estimate the size of the smallest ring, estimate the percentage of the airway involved with CTRs (as well as the position of the rings within the trachea), and evaluate the bronchial anatomy. This evaluation should be performed with utmost caution using the smallest possible telescopes because any airway edema in the region of the stenosis may transform a compromised airway into a critical airway. 57
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58 In patients with distal tracheal stenosis, adequate evaluation cannot be made with a ventilating bronchoscope. Rather, the Hopkins rod telescope (removed from the bronchoscope) should be introduced independently into the airway to evaluate the stenosis. The initial bronchoscopic view is often sufﬁcient to establish the diagnosis. In cases of signiﬁcant stenosis, it is preferable to identify only the proximal extent of the tracheal stenosis without fully evaluating the distal airway (rather than forcing a telescope through a narrow stenosis); this avoids the risk of decompensation. Because 50% of children with CTRs have a tracheal inner diameter of approximately 2 mm at the time of diagnosis, the standard interventions for managing a compromised airway are not applicable. The smallest endotracheal tube (2.0 mm inner diameter [ID]) has a 2.9 mm outer diameter (OD) and the smallest tracheotomy tube (2.5 mm ID) has an OD of 3.6 mm. Neither of these will pass through the stenotic segment without causing severe damage to mucosa or tracheal rupture. Because the stenosis usually extends to carina, bypassing the stenosis risks bronchial intubation. This may leave extracorporeal membrane oxygenation (ECMO) as the only viable alternative for stabilizing the child in the event of decompensation following bronchoscopy. If a child is decompensating and not ventilating effectively, intubation proximal to the CTRs is advisable in an effort to avoid ECMO. The endotracheal tube should be sized to the cricoid, with the Murphy eye just below vocal fold level. Given that it is unusual for the proximal two tracheal rings to be complete, shallow intubation is achievable in most children with CTRs. Nasal intubation to allow tube stabilization is advisable. Ventilation requires a long inspiratory and even longer expiratory phase to allow air to pass through the stenosis. Higher ventilator pressures may be tolerated because the stenosis ensures that the lungs are not exposed to the same pressures as the subglottis. Maintenance of high humidity levels is essential because mucus accumulation in the area of stenosis may be life-threatening and is often heralded by rising CO2 levels rather than low oxygen saturation. In view of the high proportion of patients with other congenital anomalies, a thorough diagnostic investigation should include a contrast-enhanced computed tomography (CT) scan of the chest with 3-dimensional reconstruction and an echocardiogram.3.These tests will identify any coexisting cardiovascular pathology, which should be repaired concurrently with the tracheal repair. As mentioned previously, the most common cardiovascular anomaly is PAS, though intracardiac anomalies and the presence of a persistent left superior vena cava draining to the coronary sinus with absence of the innominate vein are also common. Nearly one third of children with CTRs have a tracheal (or pig) bronchus. Subglottic stenosis is present in 20%. The presence of pulmonary hypoplasia or agenesis, more commonly affecting the right lung, may cause mediastinal shift and aortic compression of the already stenotic trachea. Although most children with CTRs require early tracheal reconstruction, 10% to 15% have sufﬁcient tracheal growth to avoid the need for tracheal reconstruction. A further 10% to 15% eventually outgrow their trachea and require late repair.
The recommended surgical technique is the slide tracheoplasty. This approach yields signiﬁcantly better results than any other tracheal reconstruction technique and is applicable to all anatomic variants of CTRs.4–9 Most children with CTRs have distal tracheal involvement. If the distal third of the trachea is involved or if there are coexistent cardiovascular anomalies that require repair, we recommend repair using cardiopulmonary bypass. More than 90% of children requiring slide tracheoplasty for CTRs fall into this category. If only the upper or mid-trachea is involved and there are no cardiovascular anomalies requiring repair, then a slide tracheoplasty may be performed with routine anesthesia through a cervical approach.10 Although three decades ago this diagnosis carried a mortality rate as high as 50% to 80%, we now expect a survival rate exceeding 90%. In the current era of the slide tracheoplasty, a patient’s prognosis is less about the trachea than about other coexisting anomalies.
Other Etiologies Other rare causes of tracheal stenosis include sleeve trachea and cartilage hypoplasia.11,12 Sleeve trachea is exclusively seen in children with craniosynostoses (Crouzon, Apert, and Pfeiffer syndromes), in which the trachea comprises a single sheet of cartilage with no deﬁnable tracheal rings; the cartilage edges may posteriorly overlap, causing stenosis.11 In stenosis associated with cartilage hypoplasia, a short segment of the distal trachea or mainstem bronchi (usually right) is generally affected.12 In both of these conditions, slide tracheoplasty (described below) is effective.
Vascular Compression Vascular compression of the airway, particularly innominate artery compression, is not uncommon. In most cases, however, it is asymptomatic or minimally symptomatic. Although symptomatic vascular compression of the trachea or bronchi is rare, it is associated with marked symptoms, including biphasic stridor, retractions, a honking cough, and “dying spells.” Symptoms tend to exacerbate when the child is distressed. Forms of vascular compression affecting the trachea include innominate artery compression, double aortic arch, and PAS. Vascular rings that result from a right aortic arch, retroesophageal left subclavian artery, or a left-sided ligamentum arteriosum are less likely to be associated with airway compromise. Bronchial compression by either the pulmonary arteries or aorta may be signiﬁcant, but in the absence of associated major cardiac anomalies, it is typically a unilateral problem. The diagnosis of airway compression is best established with rigid bronchoscopy. Thoracic imaging then assists in determining the relevant vascular anatomy. Imaging modalities generally include high-resolution CT with contrast enhancement and 3-dimensional reconstruction, magnetic resonance imaging (MRI), magnetic resonance angiography (MRA), and echocardiography. Although imaging is used primarily to
Tracheobronchial Issues in Congenital Heart Disease assess intrathoracic vasculature, excellent images of the airway and the thymus gland can also be obtained; this comprehensive anatomic view aids in surgical planning. The surgical management of symptomatic vascular compression must be tailored to address the speciﬁc pathology. Strategies for managing innominate artery compression include thymectomy and aortopexy; however, if little thymus is present, an alternative procedure is reimplantation of the innominate artery more proximally on the aortic arch. A double aortic arch requires division of the smaller of the two arches, which is usually the left. A relatively common ﬁnding is compression of the left bronchus between the left pulmonary artery and the descending aorta. In a symptomatic child (left lung hyperinﬂation or poor mucus clearance), a posterior aortopexy of the descending aorta through a left lateral thoracotomy may be effective. PAS is another common cause of vascular compression. As noted earlier, there is a strong association between PAS and CTRs. As such, the presence of either diagnosis requires evaluation for the other. Although not all children with CTRs in our previously reported series2 required operative reconstruction, all patients with coexistent PAS have required it. We preferentially repair both anomalies concurrently, with reimplantation of the left pulmonary artery onto the main pulmonary artery in a normal anatomic position anterior to the trachea.13 Although it is alluring to transect the trachea and transpose it behind the PAS during concurrent tracheoplasty rather than repairing the PAS, this technique should only be considered in patients with a severely hypoplastic or absent right lung. The redundant length of the unrepaired PAS is at risk of kinking, thus leading to occlusion of the artery. Although alleviating vascular compression improves the airway, it takes time for the airway to completely normalize. This is a consequence of longstanding vascular compression having adversely affected the normal cartilaginous development of the compressed segment of trachea, with resultant cartilaginous malacia or stenosis. Until the airway normalizes, children who are persistently symptomatic may require stabilization with a tracheotomy. Tracheal stabilization with the use of intratracheal stents is occasionally advocated; however, the incidence of complications in this setting is high.14 Thus, placement of a temporary tracheotomy is a more desirable alternative.
Tracheomalacia Isolated tracheomalacia is uncommon and is typically associated with other concurrent aerodigestive or vascular anomalies.15 The most common aerodigestive anomalies are esophageal atresia, usually with a tracheoesophageal ﬁstula, and laryngeal clefting. Tracheomalacia may also be seen with vascular compression, especially in patients with a double aortic arch. Malacia may persist for months following repair. It may also be seen both in patients with severe pectus deformities and in those with mucopolysaccharidosis. In the latter patient population, tracheomalacia may be progressive. Because the endoscopic appearance of tracheomalacia does not
59 always correlate with the severity symptoms, it is more prudent to treat symptoms rather than endoscopic ﬁndings. Spontaneous improvement with time and growth typically occurs in the majority of children. However, intervention may be required in symptomatic children. Surgical management of tracheomalacia may focus on bypassing the malacic segment of trachea. This can be accomplished using a tracheotomy with a tube of sufﬁcient length to bypass the malacic area (eg, using a pediatric-length tube in a neonate). Flexible endoscopy through the tube is mandatory to ensure that the tube bypasses the area of malacia but is not down a bronchus. An additional surgical option is to pexy the airway anteriorly, thus relieving the compression. Typically, the thymus is removed and the aorta or innominate artery is then sutured to the back of the sternum, which pulls the trachea anteriorly and reduces the degree of compression. The anterior trachea should not be exposed, but should be left attached to the posterior aspect of the aorta and/or innominate artery. To ensure that an adequate result is achieved, it is useful to perform intraoperative ﬂexible endoscopy through the endotracheal tube before tying the sutures. The outcome is dependent on the distance the aorta and/or innominate can be moved forward, which in turn, is dependent on the size of the removed thymus. Therefore, children with DiGeorge syndrome are rarely good candidates for aortopexy.
Bronchomalacia In patients with bronchomalacia or tracheobronchomalacia, surgery is not a viable option. If symptoms are severe enough to warrant intervention, tracheotomy and positivepressure ventilation are advisable. As with tracheomalacia, bronchomalacia improves over time. Internal stents are best avoided because they carry signiﬁcant short- and longterm risks of scarring, granulation, stent occlusion and stent migration.14 Although these stents have historically been problematic,16–18 ongoing research on bioabsorbable external stents is promising.
Cardiac Surgery in the Child With a Tracheotomy Cardiac surgery is occasionally required in infants or children in whom a tracheotomy has already been placed. Although surgical repairs are ideally performed without a tracheotomy present because of the risk of infection from the stoma, these repairs generally cannot be delayed until after decannulation. Therefore, options for management include intubation through the stoma with a reinforced endotracheal tube or intubation through the nose or mouth with temporary stoma closure. If the latter is the desired option, it is mandatory to evaluate the upper airway by performing laryngoscopy and bronchoscopy. This evaluation ensures that there is not a subglottic or upper tracheal stenosis or a suprastomal granuloma that could compromise placement of an endotracheal tube large enough to permit adequate ventilation. We recommend evaluating the airway before cardiac repair to permit
C.K. Hart and M.J. Rutter
60 planning for appropriate airway management during the repair. To temporarily close the stoma during cardiac repair, a pursestring suture is placed through a plug or sponge in the stoma. This maintains the stoma until the tracheotomy can be reinserted postoperatively.
Reconstructive Techniques Technical Approach Endoscopic techniques such as balloon dilation rarely have a role in the treatment of congenital tracheal stenosis. More speciﬁcally, they are contraindicated in the initial management of CTRs because the risk of tracheal rupture is high. However, balloon dilation may have a role after reconstruction if restenosis occurs. There are several methods for repair of CTRs, and management of this anomaly has evolved over the last 25 years. Surgical management techniques include tracheal resection, cartilage graft tracheoplasty, anterior pericardial patch, and tracheal autograft patch.19,20 At present, all of these operations have been superseded by slide tracheoplasty.
Slide Tracheoplasty In view of signiﬁcant improvement in outcomes achieved with this operation, slide tracheoplasty is considered a watershed in the management of CTRs. The operation was conceived by Tsang et al5 in the 1980s and popularized by Grillo et al6 in the 1990s. It was originally designed as an operation to repair congenital tracheal stenosis caused by CTRs. Most infants presenting with this anomaly have long-segment stenosis, with the most severe stenosis being in the distal trachea. Although the slide tracheoplasty may be performed using ECMO or jet ventilation, we prefer to use cardiopulmonary bypass to perform the repair because this approach facilitates exposure of the distal airway by allowing the heart and lungs to be partly deﬂated. Removal of the carinal lymph nodes also facilitates exposure and improves mobilization of the trachea. The extent of the tracheal stenosis is then assessed. The assessment usually requires bronchoscopic examination of the airway while a 30gauge needle is placed into the trachea from the mediastinal side; this allows the proximal and distal extent of the stenosis to be precisely identiﬁed within the chest. The length of the stenosis is then measured and its midpoint is marked. Next, the trachea is transected at or just proximal to the midpoint of the stenosis, with the transection being slightly beveled (anterior proximal to posterior distal). The transected trachea is mobilized by dissecting free the soft tissue attachments between the trachea and the esophagus of both the proximal and distal segments. Care is taken to preserve some lateral attachments to maintain a blood supply as well as to protect the vagus and recurrent laryngeal nerves. The distal segment is split posteriorly through all complete rings (to carina or down a bronchus if required) and the proximal segment is split anteriorly through the area of stenosis and into normal trachea. At the split, the trachea may be trimmed to round off either end at the transection margins to facilitate the closure. The
anastomosis is commenced from distal posterior (carinal) in a running fashion using appropriate-sized double-armed PDS sutures (usually 6-0 PDS in infants). Four to six throws of the suture are generally placed posteriorly and tightened with a nerve hook. The anastomosis is then continued up the left and right sides of the trachea, with the sutures placed through cartilage and mucosa, therefore being exposed intraluminally. An effort is made to evert the lateral sides of the anastomosis to prevent internal bunching of the anastomotic lines (a “ﬁgure 8” trachea). Before the anastomotic suture lines rejoin in the midline at the proximal anterior aspect of the repair, the trachea is suctioned clear. The anastomosis is completed with a single proximal knot being thrown, leak tested (to 35 cm water pressure), and marked with a ligature clip applied to the proximal and distal ends of the anastomosis (to aid in radiographic positioning of the endotracheal tube postoperatively). Fibrin glue is then applied to the anastomosis. The patient is reintubated and taken off cardiopulmonary bypass, and the chest is closed. At completion of the procedure, the airway is reevaluated with a ﬂexible bronchoscope to ensure that the repair is adequate and that blood and secretions are removed. A 2.8 mm ﬂexible bronchoscope with a suction port can be placed into a 3.5 mm endotracheal tube and still allow for ventilation during the evaluation. If the patient’s cardiovascular status permits, extubation is usually achieved within 24 hours. The slide tracheoplasty is a versatile procedure. If required, it is possible to slide: the entire length of the trachea; down a bronchus; into the anterior cricoid; or past a tracheal (pig) bronchus. The intrathoracic slide tracheoplasty may also be used to repair stenosis associated with absent tracheal rings, a sleeve trachea, or distal tracheoesophageal ﬁstula. In addition, it may be used to repair an acquired tracheal stenosis.
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61 16. Jacobs JP, Quintessenza JA, Andrews T, et al: Tracheal allograft reconstruction: the total North American and worldwide pediatric experiences. Ann Thorac Surg 1999;68:1043-1052. 17. Fishman JM, Wiles K, Lowdell MW, et al: Airway tissue engineering: an update. Expert Opin Biol Ther 2014;10:1477-1491. 18. Fishman JM, De Coppi P, Elliott MJ, et al: Airway tissue engineering. Expert Opin Biol Ther 2011;111:623-635. 19. Backer CL, Mavroudis C, Gerber ME, et al: Tracheal surgery in children: an 18-year review of four techniques. Eur J Cardiothorac Surg 2001;19:777-784. 20. Backer CL, Mavroudis C, Holinger LD: Repair of congenital tracheal stenosis. Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu 2002;5:173-186.