Esophageal Atresia/Tracheoesophageal Fistula

An understanding of the esophageal blood supply is crucial to the successful repair of atresia and/or fistulas. The esophagus can be divided into several segments on the basis of its blood supply.The cervical portion of the esophagus is well vascularized; interrupting a vessel to this segment during surgical manipulation is not catastrophic. The cervical esophageal portion is supplied by the inferior thyroid artery and accessory vessels derived from the common carotid, subclavian, vertebral, ascending pharyngeal, superficial cervical, and costocervical arteries. The thoracic portion of the esophagus has a segmental blood supply. The connections in this region are the most tenuous, and care should be taken to reduce the risk of ischemia during mobilization of this segment.The region with the largest gap between arteries supplying the esophagus is at the level of the aortic arch. The bronchial arteries provide the main vascular supply at this level; 1 to 3 bronchial branches enter the esophagus at the level of the tracheal bifurcation. Variable branches originating directly from the aorta may also be present in this region. Three unpaired esophageal branches that arise directly from the aorta supply the lower thoracic esophagus. These branches may anastomose with branches from the intercostal and bronchial arteries. Branches from the internal mammary and carotid arteries may also be present here. The abdominal esophagus is vascularized by the ascending branch of the left gastric artery, as well as by branches from the left inferior phrenic artery.Prior to surgical procedures, the position of the aortic arch should be confirmed, and the surgical approach should be performed on the side opposite the aortic arch. A right-sided aortic arch occurs in 5% of infants with EA.The esophagus is innervated largely by the autonomic nervous system. Sympathetic innervation plays a minor role and arises from the pharyngeal plexus in the upper esophagus and the stellate ganglia in the lower cervical and upper thoracic portions. The aortic plexus, sympathetic chain, and splanchnic nerves supply the remainder of the thoracic esophagus. In the abdominal segment, fibers from the celiac ganglion pass around the left gastric and inferior phrenic arteries to innervate the esophagus. Parasympathetic innervation to the esophagus is provided by the vagus nerve.Parasympathetic function includes stimulation of smooth muscle and secretory activity. The vagus nerve also aids the sphincteric function of the lower esophagus. The recurrent laryngeal nerves should be noted as they pass cranially in a groove between the esophagus and trachea, supplying the cervical and upper third of the thoracic esophagus. The vagus nerves descend caudally; they arborize to form the esophageal plexus and then subsequently coalesce into the left and right vagal trunks, which overlie the anterior and posterior lower esophagus, respectively.Because of its course along the esophagus, the vagus nerve is another helpful landmark during surgical esophageal procedures. Disruption of the vagus during surgical manipulation has been proposed as a mechanism of dysmotility after esophageal repair, but manometric findings have confirmed the inaccuracy of this hypothesis. Injury of vagal fibers during esophageal mobilization may, however, further adversely affect motility. Several other organs and structures should be noted during surgical esophageal repair. The thoracic duct is vulnerable near the cervical esophagus, and the locations of the trachea and aorta should be confirmed with palpation during a surgical procedure. Because the upper esophageal pouch may be virtually fused to the trachea, care should be taken not to enter the trachea when the upper pouch is mobilized. Contact of the esophageal wall and left atrium of the heart caudal to the carina is also noteworthy. In this region, the pericardium is the only structure that separates these 2 organs. Of special note in TEF repair, the left main bronchus crosses the ventral esophageal surface. Confirmation of bronchi locations is critical to fistula repair, especially in a trifurcation TEF. The first clinical sign of an infant with EA is maternal polyhydramnios resulting from the infant’s inability to swallow and absorb amniotic fluid through the gut. Polyhydramnios is seen in infants with many diagnoses, and only 1 in 12 infants with polyhydramnios has EA; however, polyhydramnios is seen in 95% of infants who have EA and no fistula and in 35% of patients who have EA with a distal fistula. Increased pressure caused by amniotic fluid accumulation results in a greater number of premature births and neonates with low birth weight. One third of infants with EA weigh less than 2250 g. Most infants with EA become symptomatic within the first few hours of life; however, children with an isolated fistula have more subtle symptoms that may not be recognized initially. Excess salivation and fine, frothy bubbles in the mouth and, sometimes, the nose result from an inability to swallow. Any attempts at feeding can result in choking, coughing, cyanotic episodes, and food regurgitation. The presence of a fistula increases respiratory complications, which result from aspiration of food and secretions into the trachea and lungs. Pneumonitis and atelectasis develop quickly in the affected neonate, and rattles heard during respirations are common. Fistulas also allow air to enter the stomach and intestines, leading to abdominal distention. With atresia alone, the abdomen appears scaphoid. Many anomalies are associated with EA; 50-70% of children with EA have some other defect. The acronym VACTERL (which stands for v ertebral, a norectal, c ardiac, t racheal, e sophageal, r enal, and l imb) describes the most common combination of defects associated with EA.21 Cardiac abnormalities are the most common, especially ventricular septal defects and tetralogy of Fallot. Imperforate anus and skeletal malformations might also be found on examination. In the absence of such associated anomalies, the physical examination findings in infants with EA are fairly unremarkable. Traditionally, the prognosis for children with EA and/or TEF was centered on the Waterston risk classification, which is based on birth weight and the presence of pneumonia and associated congenital abnormalities. Because of advancements in neonatal care, however, this risk classification is no longer prognostic. Pneumonia may be successfully treated, except in some infants with severely low birth weight. Currently, cardiac and chromosomal abnormalities are the most significant causes of death. Regardless of the classification scheme, infants with a birth weight less than 1500 g, major congenital cardiac abnormalities, severe associated anomalies, preoperative ventilator dependence, and/or a long esophageal gap are at an increased risk. Preoperatively, the greatest risk to a child with EA and/or TEF is aspiration. Gastric rupture has been reported in patients with TEF who are receiving ventilatory support as a result of air that is forced through the fistula into the distal esophagus and then into the stomach. The severity of complications after EA repair is often dictated by the extent of the repair required. Primary anastomosis and fistula closure has fewer complications than esophageal replacement. The length of the gap between the esophageal segments is directly related to possible complications; patents with longer gaps experience a higher complication rate. The most common complications include anastomotic leak, recurrent fistula, stricture, and gastroesophageal reflux (GER). Anastomotic leakage into the mediastinum occurs in 14-21% of children that have undergone surgical EA repair. Leaks can result from the small, friable lower segment, ischemia of the esophageal ends, excess anastomotic tension, sepsis, technically poor suturing techniques, and inaccurate mucosal apposition. Most leaks are small, occur later (after the first 48 h after surgery), and require only conservative management with cessation of oral intake (total parenteral nutrition [TPN]) and antibiotics. Spontaneous healing occurs in 95% of leaks when a mediastinal drain is present. More significant leaks occur early (within the first few days) and should be explored immediately. Major anastomotic disruptions occur in only 3-5% of leaks, but large leaks can be fatal and require surgical repair. Mediastinal leaks can lead to TEF recurrence; therefore, they should be monitored carefully. Fistula recurrence between the esophagus and trachea is observed in 3-14% of patients treated for EA with TEF, EA without TEF, or H-type TEF. Fistulas usually recur within a few months, but they may recur as late as 2 years after surgery. An anastomotic leak with local inflammation and erosion at the previous repair site, ischemia, and surgical dissection too near the trachea may cause a recurrent fistula. This condition should be suspected when choking episodes occur during feeding and/or recurrent pneumonia is observed. The best methods of diagnosis are bronchoscopy and esophagography under videofluoroscopic guidance with the patient in the prone position and with bolus injections of contrast agent into a nasoesophageal tube. Fistulas do not close spontaneously and require surgical division and ligation. About 10-20% of cases recur after the first TEF recurrence. Esophageal strictures occur in 40% of children after surgical EA repair. Strictures result from natural healing and are caused by fibrosis, a difference in the sizes of the 2 anastomosed segments, tension, and GER. Leaks, as well as the use of a 2-layer anastomosis and/or silk sutures, enhance stricture formation. Strictures may be diagnosed with barium swallow examination or esophagoscopy. Although barium swallow studies aid in stricture reduction by dilating the anastomotic site, decreasing the size discrepancy between the 2 segments, and loosening the fibrosis of healing, it is not completely effective, and dilations are required for resolution. Dilation is 90% effective, but strictures that do not respond to dilation must be surgically resected. GERD is a common complication, occurring in 40-70% of patients after EA repair. Symptoms of GER include coughing, apnea, recurrent pneumonia, failure to thrive, and stricture formation. A barium swallow examination may demonstrate GER, which is caused by tension, dysmotility of the lower esophagus, and an altered angle of Hiss resulting from distal esophageal mobilization. GER may be medically treated by keeping the patient in a prone head-up position after feeding; by thickening the food; and by giving smaller, more frequent meals. If problems persist, acid-reduction agents such as histamine H2 -receptor blockers and prokinetic agents may be administered. If medical therapy is unsuccessful, fundoplication may be considered. Fundoplications are required in about half of the patients with GER. GER tends to diminish with time, but long-term GER leads to mucosal changes such as esophagitis and Barrett esophagus. Additional complications in infants with EA/TEF include the following:
Altered esophageal peristalsis (seen in all patients)
Tracheomalacia (seen in all patients)
Diverticula at the myotomy site Pulmonary complications (eg, hacking cough, bronchitis, frequent pneumonia)
Swallowing difficulties, Dyspepsia, Anastomotic dehiscence, esophageal stenosis,Failure to thrive,Chest wall deformities, scoliosis
An esophageal substitution causes additional complications. Esophageal replacement has been associated with an increased surgical morbidity rate and a 68% complication rate. These conditions include the following:
Colon
Early complications
+ Cervical leaks (which heal well)
+ Pulmonary problems
+ Graft necrosis
Late complications
Redundancy
GER
+ Anastomotic stenoses
+ Strictures
+ Deformity
Thin-walled, has poor function
Subject to pathology (polyps, villous adenomas)
Slow transit that leads to dilatation over the patient’s lifetime (which leads to anemia, poor weight gain, recurrent pulmonary infections, and redundancy)
Intestinal obstruction in 20% of patients
Colon graft ulceration in 10% of cases (which leads to symptomatic GER in 30% of cases, especially in retrosternal placements; this may lead to Barrett epithelium in the lower esophagus if the lower segment is unused)
Limited mucosal acid resistance (the colon tends to dilate and form loops)
Gastric tube
Has frequent leaks and strictures
Has high incidences of fistulas, stenoses, and peptic ulcerations
May lead to peptic esophagitis
Produces extensive GER in cervical esophagus, which may lead to peptic ulceration and Barrett epithelium
Gastric transposition
Leakage in 6% of cases
Stricture at the anastomosis in 12% of cases
Microvasculature easily disturbed with handlin, Late dilatation
Long-term effects of intrathoracic stomach ulceration (chronic GER, Barrett epithelium)26
Aspiration
Nutritional concerns
o In 25% of children, height and weight after 1 year is less than 3rd percentile
o Severe dumping is common
o Decreased pulmonary function
o Resultant depleted iron stores
* Jejunum
o Infarction is common
o High incidence of peptic ulceration
o High free graft failure rate

Preferred Examination
Prenatally, ultrasonographic findings may suggest a diagnosis of isolated EA or EA and TEF; however, prenatal EA detection rates are low, and if suspected, the diagnosis must be confirmed postnatally. In neonates in whom EA and/or TEF is suspected, posteroanterior and lateral plain chest radiographs should be obtained first. The patient’s inability to pass a rigid nasogastric tube from the mouth to the stomach is diagnostic of EA and/or TEF, but this finding should be confirmed with radiographic visualization of the tube coiled in the proximal pouch.Contrast-enhanced studies are rarely indicated because of the risk of aspiration, but they may be necessary to identify or locate a fistula. Only an experienced radiologist should perform contrast-enhanced studies with fluoroscopic control.27 Endoscopy and/or bronchoscopy may be performed to locate or rule out TEFs.
Limitations of Techniques
Sonographic evaluation will reveal the first findings suggestive of a congenital anomaly, but it is not conclusive. Many conditions involve polyhydramnios and a small or absent stomach bubble at ultrasonography.28 Visualization of a dilated proximal pouch is suggestive of EA, but further tests are necessary to confirm the diagnosis. In addition, sonograms may not give any indication of EA when it is present, and often, a fistula is not seen. Plain radiographs provide much information, including findings for EA confirmation and depiction of the side of the aortic arch side, as well as the presence of any vertebral or other associated anomalies. Barium studies performed after the surgical placement of a gastrostomy tube may be used to evaluate the gap length and associated GI abnormalities, such as duodenal atresia or malrotation; however, radiographs may not always demonstrate the presence of a fistula.
Differential Diagnoses
Other Problems to Be Considered
A tear of the oropharynx or esophagus should be considered, especially in patients who underwent vigorous attempts at feeding tube placement following delivery. The type of atresia and/or fistula should be considered as well. EA and TEF types include the following: isolated EA, EA with a proximal TEF, EA with a distal TEF, EA with proximal and distal TEFs, and isolated (H-type) TEF.