Asian Cardiovasc Thorac Ann 2005;13:4-10
© 2005 Asia Publishing EXchange Ltd
Surgical Repair of Double Aortic Arch: 16-year Experience
Ganesh Shanmugam, MCh,
Kenneth Macarthur, FRCS,
James Pollock, FRCS
Department of Cardiac Surgery, Royal Hospital for Sick Children, Scotland, UK
For reprint information contact: James Pollock, FRCS Tel: 44 141 201 0269 Fax: 44 141 201 9204 Email: jim.pollock{at}yorkhill.scot.nhs.uk, Department of Cardiac Surgery, Royal Hospital for Sick Children, Dalnair Street, Glasgow G3 8SJ, Scotland, UK.
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ABSTRACT
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Double aortic arch (DAA) is a complete form of vascular ring causing tracheoesophageal compression. We analyzed long-term results of a series of DAAs, over a period of 16 years. Between 1987 and 2003, 29 children underwent surgery for airway and/or esophageal compression secondary to a DAA. Dominant symptoms were stridor, dysphagia, choking episodes, and life-threatening apneic spells (n = 7). Diagnosis was established by barium studies, bronchoscopy, echocardiogram, angiogram, computed tomography (CT), and magnetic resonance imaging (MRI). Seven patients had concurrent cardiac anomalies. Two children had an associated tracheoesophageal fistula. Surgery was accomplished by left thoracotomy (n = 25), right thoracotomy (n = 2) or median sternotomy (n = 2). The operative mortality was zero. There was one late death due to respiratory failure. Four (13.8%) patients had a surgical complication (chylothorax, 3 cases; acute renal failure, 1 case). Follow-up (mean 7.1 years; range 6 months to 16 years) was complete in all patients, and showed complete improvement in 22 patients and partial improvement in 6 patients. Early surgical repair of DAA is associated with low mortality, and results in marked symptomatic relief in most patients. Patients with tracheomalacia or associated asthma, constitute a high-risk group and may manifest persistent symptoms and require adjunctive procedures.
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INTRODUCTION
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Disturbances in the complex embryonic development of the aortic arch system result in a variety of vascular anomalies. The term "vascular ring" refers to any vascular anomaly causing tracheoesophageal compression. "Complete vascular rings" generally refer to arterial derivatives of the branchial arch system that encircle both the trachea and esophagus. Double aortic arch (DAA) is the anomaly that usually produces the most severe airway compression in the youngest patients. The purpose of this study was to review our experience of the surgical repair of DAA over a period of 16 years.
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PATIENTS AND METHODS
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We reviewed the hospital records of 29 patients with symptomatic tracheoesophageal compression due to DAA between 1987 and 2003. Adults and children with other forms of vascular ring were excluded. There were 2 neonates, 18 infants and 9 children. Mean age at surgery was 7.5 days (range 5–10 days) for the neonates, 5.7 months (range 1 month to 1 year) for infants, and 4.3 years (range 14 months to 8 years) for children. There were 17 males (58.6%) and 12 females (41.4 %). Symptoms on presentation are outlined in Table 1
. Investigative procedures are listed in Table 2.
Our patients were divided into the following categories:
- Group 1, balanced arches (n = 2).
- Group 2, right arch dominance (n = 25). In this group, 16 patients had patency of both arches while 9 had left arch atresia. In the latter subgroup, 8 had an atretic segment between the ligament and the descending aorta (DTA), while 1 patient had an atretic segment between the left carotid and left subclavian arteries.
- Group 3, left arch dominance (n = 2). No instance of right arch atresia was recorded. The DTA was left sided in 25 patients and right sided in 4. Of the 4 patients with a right DTA, 2 had left arch dominance and 2 had codominant arches.
Table 3 lists the associated cardiac and non-cardiac anomalies.
Surgical access was by left thoracotomy in 25, by right thoracotomy in 2, and by median sternotomy in 2 patients. Both patients with codominant arches had associated cardiac defects and were operated through a median sternotomy. The operative approach in Group 2 consisted of division of the atretic segment through a left thoracotomy. In Group 3, the right arch was divided between the right subclavian artery and the DTA through a right thoracotomy. The ligament was divided, and the trachea and esophagus freed from surrounding tissues, in all patients.
Cardiopulmonary bypass was used for simultaneous correction of an associated intracardiac malformation in 2 patients – ventricular septal defect (VSD) with atrial septal defect (ASD) and patent ductus arteriosus (PDA) in 1 patient, and VSD and anomalous origin of the left coronary artery from the pulmonary artery in the other. Concurrent coarctation repair was performed in 1 child. Four patients underwent an aortopexy, in addition to arch division.
All survivors had 6 monthly reviews for 2 years and then yearly. Follow-up data from 6 months to 16 years (mean 7.1 years) were available for 28 patients. For patients with persistent respiratory symptoms and those with a history of obstructive pulmonary disease, pulmonary function tests were obtained.
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RESULTS
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There were no intraoperative deaths. There was one late postoperative death early in our series. This infant had division of DAA in addition to repair of an ASD, a VSD, and division of a PDA. She had severe tracheomalacia preoperatively, and recurrent episodes of bronchopneumonia and sepsis, and could not be weaned from the ventilator, despite a tracheostomy. She died of respiratory failure. Three children had chylothoraces; 2 of them required thoracic duct ligation. One patient had sepsis and transient renal failure. Six children were extubated in the operating room, and 18 more within 24 hours. Three patients were extubated within 1 week (all 3 had tracheomalacia preoperatively), while 1 patient required prolonged ventilation (14 days). This patient had tracheomalacia and bronchial asthma. Mean intensive care and hospital stays were 1.9 (range 1–19) days and 8.3 (range 3–30) days, respectively.
Complete symptom resolution occurred in 22/29 patients (75.9%) and partial improvement in 6 patients (persistent wheeze, 3; stridor, 3). The 3 asthmatic children continued to be symptomatic. All 3 patients who had residual stridor had preoperative tracheomalacia. Patients with partial improvement (bronchial asthma, 3; residual stridor, 3) were submitted to lung function tests. Those with asthma had abnormal flow volume loops indicative of significant central airway obstruction; others had normal studies.
Of the 9 patients with tracheomalacia, 3 (33.3%) had residual stridor while 5 (55.6%) had complete resolution. On serial follow-up, all 3 patients with residual stridor improved over time, and no further surgery was required.
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DISCUSSION
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In 1945 Gross accomplished the first successful surgical intervention for a DAA.1 The development of vascular rings was detailed by Edwards.2 In the embryonic aortic arch system, the ventral aorta is linked by six pairs of arches to two dorsal aortae, which join to form the single dorsal aorta. The right fourth arch usually involutes, leaving a normal left arch. Left fourth arch involution results in a right aortic arch. Classical DAA anatomy develops when both fourth arches persist.
One patient had a DiGeorge syndrome, and 1 had a VACTERL (Vertebral, Anal, Cardiovascular, Tracheo-Esophageal, Renal, and Limb) association. Brzezinska-Kolarz et al3 reported familial recurrence of DAA, supporting a genetic etiology. Cytogenetic examination of their patients disclosed pericentric inversion of chromosome 9. Symptomatic tracheobronchial compression varies inversely with the severity of compression.4 Tracheal compression causes airflow obstruction and decreased mucociliary clearance of secretions, leading to recurrent bronchopulmonary infections.4 Reflex apnea is hypothesized to be a type of respiratory arrest that occurs when vagal afferent nerves are stimulated. Esophageal compression by the DAA causes it to bulge forward, indenting the membranous trachea and exacerbating respiratory distress. Esophageal compression also leads to regurgitation and aspiration pneumonia.4
The ascending aorta divides into two arches, which encircle the trachea and the esophagus and join posteriorly to form the DTA. The right arch gives rise to the right carotid and right subclavian arteries. The left carotid and left subclavian arteries arise from the left anterior arch (Figure 1). Both arches may be patent, or an atretic segment may exist at any location on either arch.
The Congenital Heart Surgery Nomenclature and Database Project5 grouped DAA into three categories: dominant right arch, dominant left arch, and balanced arches. In patients with right arch dominance, those with a patent left arch out number those with an atretic left arch. Depending on the location of the atresia,6 these arches are subclassified (Figure 2) as:
- Subtype 4: proximal to the left common carotid artery;
- Subtype 3: between the left common carotid artery and the left subclavian artery;
- Subtype 2: between the left subclavian and left ductus or ligamentum arteriosum;
- Subtype 1: between the left ductus or ligamentum arteriosum and DTA.
This is important to plan the site of operative division of the vascular ring.
In patients with left arch dominance, the minor right arch typically is patent. More commonly, the DTA is on the left side rather than the right. In patients with a right DTA, the arches are right anterior and left posterior. Of the 4 patients who had right DTAs in our series, 2 had codominant arches and 2 had left arch dominance. Tracheobronchial anomalies,7 found in patients with DAAs include severe dyskinesia, tracheomalacia (9 patients in our series) or tracheobronchial hypoplasia.
The most frequently associated lesions are tetralogy, VSD, coarctation, PDA, and esophageal atresia. An undiagnosed arch may complicate repair of esophageal atresia.8 Two patients had repair of esophageal atresia prior to arch division. One patient also had a Nissen’s fundoplication for severe gastroesophageal reflux.
The severity of compression and the onset of symptoms are determined by the space between the tracheoesophageal axis and the components of the ring, and tracheoesophageal dimensions. Fleenor et al9 showed that patients with symptomatic vascular rings have significantly altered tracheal geometry. Patients with early symptoms of tracheal compression tend to have very tight rings, while those with loose rings present later in life. McLaughlin et al4 reported that only 34% were correctly diagnosed by 6 months of age. Apparent life-threatening events or death spells were present in 7 patients. Co-existent chronic pulmonary disease should be carefully documented as some patients may have persistent postoperative wheeze. We have found pre and postoperative lung function tests useful in such patients. Esophageal symptoms such as emesis, choking, or dysphagia predominate in older children and adults.
The chest radiograph establishes arch location. An ill-defined arch is often observed in patients with DAA.10 Lateral indentation of the tracheal air column may be revealed on frontal films (Figure 3A). Lateral views are evaluated for retrotracheal opacity, anterior tracheal bowing, and posterior indentation.
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Figure 3. DAA: (A) chest X-Ray shows lateral tracheal deviation; (B) barium esophagography AP view reveals bilateral indentation of the esophagus; (C) lateral view depicts posterior compression.
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In our series, we used bronchoscopy to assess upper airway problems, the presence and severity of tracheomalacia, and of an associated tracheoesophageal fistula. Bronchoscopy was performed in 14 patients and showed tracheomalacia in 9. Possible airway problems can be anticipated, thus minimizing postoperative respiratory difficulties. However, it cannot always define the anatomy of a vascular ring. Bronchoscopy can cause tracheal edema, which may worsen tracheal obstruction.
Barium esophagography reliably diagnosed a DAA in 19/20 patients in our series. Bilateral esophageal indentation (Figure 3B
) is observed on the anteroposterior view, forming a reverse S sign with the right-sided indentation being superior, while a posterior indentation is observed on the lateral view (Figure 3C). However, the extant anatomy of a vascular ring that many authors think necessary for accurate preoperative planning, cannot always be delineated by esophagography. Doppler echocardiography depicts the great vessels, but structures without a lumen, such as a ligamentum arteriosum or an atretic arch, and compressed midline structures are difficult to identify. Fourteen patients in our series had echocardiograms; revealing associated intracardiac problems in 7 of them. Echocardiography was non-diagnostic in 4/14 patients.
Aortography provides detailed information but cannot distinguish between an atretic arch and complete interruption. It was used earlier in our series, but is no longer used solely for this indication.
Computed tomography (CT) reveals vascular, tracheobronchial (Figure 4A), and esophageal anatomy. In patients with a DAA there are four separate brachiocephalic vessels (instead of the normal three) in the superior mediastinum grouped around the trachea. This is called the "four vessel" sign (Figure 4B). Spiral CT (Figure 5) provides images of even greater detail, especially for showing the dominant arch.11
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Figure 4. Axial CT pictures depict (A) the right and left arches surrounding the trachea and (B) the "four vessel" sign.
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Figure 5. Spiral CT shows the ascending aorta dividing into two arches, the branches and their fusion to form the DTA. Both arches are patent.
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The ability of MRI12 to demonstrate vascular channels due to the flow-void phenomenon makes it well suited to diagnose DAA (Figure 6). As a result of its noninvasive nature, the absence of need for contrast, and the ability to obtain multiplanar images of the airway and mediastinal vessels, magnetic resonance angiography is emerging as the study of choice to delineate vascular rings. Very young patients require sedation, which could be risky in those with existing airway compromise.
Both CT (n = 11) and MRI (n = 3) confirmed the diagnosis of a DAA in all patients. Our current protocol is to use CT scanning to establish the diagnosis, and MRI if greater anatomical detail is required.
Achiron et al13 described a novel, sonographic approach for in-utero aortic arch evaluation. The normal left aortic arch was defined by the V-shaped appearance of the junction between the ductus arteriosus and aortic arch, with the trachea situated posteriorly. DAAs were diagnosed when the great vessels appeared U-shaped, with an intermediate location of the trachea.
Reported complications from unrepaired DAA include aortic dissection.14 McKeating et al15 reported fatal hematemesis due to erosion by a nasogastric tube into the right component of an unrecognized DAA.
Non-surgical management is variably effective for patients with loose vascular rings who are mildly symptomatic. Asymptomatic patients may become symptomatic when a respiratory infection supervenes and causes tracheal edema.11 Most patients however are symptomatic at presentation. An increased incidence of persistent postoperative symptoms, secondary to longstanding tracheal compression has been reported. We therefore recommend surgical division in all patients with DAA.
A left thoracotomy provides the best access to the middle and posterior mediastina in most patients, especially those with a dominant right arch. The recurrent laryngeal and vagus nerves are identified and avoided. Division of the smaller arch is performed while adequate flow in the arch vessels and the DTA are maintained. Simple ligation and division can cause ligature slippage and catastrophic hemorrhage. Aortopexy is necessary if the two ends of the divided ring do not spring apart naturally to relieve the compression.16 The threshold to perform aortopexy should be low, especially in those with preoperative tracheomalacia or laryngomalacia. The remnant arch is tacked to the anterior chest wall or the back of the sternum, by interrupted pledgetted mattress sutures through the adventitia of the vessel. Aortopexy is performed in conjunction with intraoperative bronchoscopy to confirm airway relief. The ligamentum arteriosum is always divided. The trachea and esophagus are freed from potentially constrictive bands and fibrous tissue. Closure of the mediastinal pleura is not performed to avoid adhesive scarring in the affected area around the trachea and esophagus. These mechanisms help to avoid residual tracheoesophageal narrowing and persistent symptoms. Tracheal damage due to excessive manipulation should be avoided since it can be fatal and will not be reversed immediately. When associated intracardiac anomalies require surgery through a median sternotomy, division of the double arch is performed during the same procedure.
Complications include bleeding, pleural effusion, and chylothorax. Chun et al17 reported a 10.3% incidence of chylothorax in their series of patients with vascular rings. Phrenic, vagus, or recurrent laryngeal nerve injury may occur. We previously reported18 two patients with respiratory distress due to persistent tracheomalacia despite vascular decompression. They subsequently underwent tracheal resection with symptomatic relief. Cardiopulmonary bypass can be a useful adjunct in these cases.
Video-assisted thoracoscopic surgery is applicable in patients with non-patent ring segments.19 The development of endoscopic vascular clamps will allow proximal and distal vascular control thereby extending the technique to patients with patent arches.
Tracheomalacia led to death in 1 patient and delayed extubation in 3. About 30% of patients may have persistent airway symptoms postoperatively. This may be related to tracheomalacia, persistent extrinsic airway compression or both. Other causes include an undivided ligamentum arteriosum and/or adhesive bands. In a series of 204 children with tracheoesophageal compression reported by Backer et al,10 almost 10% experienced residual tracheomalacia. These patients may benefit from an aortopexy, resection of a severely malacic tracheal segment or more complex tracheoplasty. Other techniques include tracheostomy, stenting, and external support devices. Fleck et al20 found two discrete patterns of airway narrowing and extrinsic compression in patients with persisting symptoms: (1) airway narrowing immediately abutting the intact arch; (2) narrowing of the left main bronchus; the DTA was in an abnormal midline position immediately anterior to the spine instead of being paraspinal. This leads to compression of the left main bronchus between the DTA posteriorly, and the pulmonary arteries anteriorly. Patients with DAA are prone to have midline DTAs related to the dual sidedness of their bilateral arches. This pattern of airway compression is independent of the dominant arch. Our current protocol is to evaluate patients with persistent airway symptoms with bronchoscopy and cross-sectional imaging like MRI or helical CT, to delineate extrinsic structures causing compression and to determine the airway caliber.
Based on our experience we stratified patients into three categories: (1) low risk – DAA; (2A) intermediate risk – DAA with chronic obstructive pulmonary disease; (2B) intermediate risk – DAA with tracheomalacia; (3) high risk – DAA with asthma and severe tracheobrochial abnormalities.
The rarity of these anomalies denies us sufficient numbers to draw strong conclusions. This is a retrospective study and consequently has limitations. Associated cardiovascular anomalies might have been confounding factors with respect to the respiratory complaints.
Early diagnosis and surgery are imperative to reduce the long-term sequelae of tracheobronchial compression in children. Symptoms may take longer to regress after repair in patients with longstanding preoperative symptoms. When associated cardiac lesions are present, cardiopulmonary bypass can be used to allow concomitant correction of both lesions. Postoperative care is uncomplicated, if no tracheal trauma is inflicted at surgery. Surgery affords excellent long-term resolution of symptoms. However, they may not be relieved immediately or completely, especially in those with tracheomalacia and co-existing obstructive pulmonary disease, and hence long-term follow-up is necessary.
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ABSTRACT
INTRODUCTION
