29: Esophagus Flashcards
What type of hiatal hernia is characterized as a sliding hernia from dilation of the hiatus?
Type I
[UpToDate: Hiatus hernias are broadly divided into sliding and paraesophageal hernias. The most comprehensive classification scheme recognizes four types of hiatus hernia.
Type I: Sliding hernia — A type I or sliding hiatus hernia is characterized by the displacement of the gastroesophageal (GE) junction above the diaphragm. The stomach remains in its usual longitudinal alignment and the fundus remains below the GE junction.
Type II, III, IV: Paraesophageal hernias — A paraesophageal hernia is a true hernia with a hernia sac and is characterized by an upward dislocation of the gastric fundus through a defect in the phrenoesophageal membrane.
- Type II hernia results from a localized defect in the phrenoesophageal membrane where the gastric fundus serves as a lead point of herniation, while the GE junction remains fixed to the preaortic fascia and the median arcuate ligament.
- Type III hernias have elements of both types I and II hernias and are characterized by both the GE junction and the fundus herniating through the hiatus. The fundus lies above the GE junction.
- Type IV hiatus hernia is associated with a large defect in the phrenoesophageal membrane and is characterized by the presence of organs other than the stomach in the hernia sac (eg, colon, spleen, pancreas, or small intestine).]

The phrenoesophageal membrane is an extension of what?
The transversalis fascia
[UpToDate: The distal end of the esophagus is anchored to the diaphragm by the phrenoesophageal membrane, formed by the fused endothoracic and endoabdominal fascia. This elastic membrane inserts circumferentially into the esophageal musculature, very close to the squamocolumnar junction, which resides within the diaphragmatic hiatus.
This configuration is altered during swallow-initiated peristalsis, a sequenced contraction of both the longitudinal and circular muscle responsible for bolus propulsion through the esophagus. With contraction of the esophageal longitudinal muscle, the esophagus shortens and the phrenoesophageal membrane is stretched; its elastic recoil is then responsible for pulling the squamocolumnar junction back to its normal position following each swallow. This is, in effect, “physiologic herniation,” since the gastric cardia tents through the diaphragmatic hiatus with each swallow.
The globular structure seen radiographically that forms above the diaphragm and beneath the tubular esophagus during deglutition is termed the phrenic ampulla; it is bounded from above by the distal esophagus and from below by the crural diaphragm. Physiologically, the phrenic ampulla is the relaxed, effaced, and elongated lower esophageal sphincter (LES). Emptying of the ampulla occurs between inspirations in conjunction with relengthening of the esophagus and contraction of the LES.
The repetitive stress of swallowing, as well as that associated with abdominal straining and episodes of vomiting, subject the phrenoesophageal membrane to substantial wear and tear, making it a plausible target of age-related degeneration. Another potential source of stress on the phrenoesophageal membrane is tonic contraction of the esophageal longitudinal muscle induced by gastroesophageal (GE) reflux and mucosal acidification.]

What is the 2nd most common type of esophageal cancer?
Squamous cell carcinoma
[UpToDate: The incidence of esophageal SCC varies considerably among geographic regions. The highest rates are found in Northern Iran, Central Asia, and North-Central China (the so-called “esophageal cancer belt”). Geographic variation has also been reported within individual countries. Within China, for example, rates of esophageal cancer range from 1.4 to 140 per 100,000 in the Hebi and Hunyuan counties, respectively.
Several studies have described risk factors associated with esophageal SCC. Their relative importance (from a public health perspective) was estimated in a study that determined the population attributable risk for several of the major risk factors that have been identified. The authors estimated that a history of smoking, alcohol consumption, and diets low in fruits and vegetables accounted for almost 90% of esophageal SCC in the United States. The relative importance of specific risk factors may be substantially different in other parts of the world. As noted above, the major risk factors for SCC in the “esophageal cancer belt” of Iran and Asia are not well understood, but are thought to include poor nutritional status, low intake of fruits and vegetables, and drinking beverages at high temperatures.]

How must one approach endoscopy in a patient who has ingested a caustic agent?
Do not use endoscopy if perforation is suspected and do not go past a site of severe injury
[UpToDate: The absence of oropharyngeal burns does not preclude the presence of esophageal or gastric injury. Thus, upper gastrointestinal endoscopy should be performed during the first 24 hours after ingestion in order to evaluate the extent of esophageal and gastric damage, establish prognosis, and guide therapy. Endoscopy is contraindicated in patients who have evidence of perforation. In patients who are hemodynamically unstable, endoscopy should be postponed until the patient is adequately resuscitated and is once again hemodynamically stable. If severe respiratory distress is present or there are signs of severe oropharyngeal or glottic edema and/or necrosis, the patient should be intubated for airway protection prior to endoscopy. In addition, extra care should be taken when performing an endoscopy in such patients because of the risk of perforation if the esophagus is similarly damaged.]
What is the primary blood supply to the stomach following esophagectomy?
Right gastroepiploic artery
[Left gastric and short gastrics are divided during surgery]

Bloating in a previously healthy individual is concerning for what?
Aerophagia and delayed gastric emptying
[Dx: Gastric emptying study]
[UpToDate: Patients with gastroparesis can present with nausea (93%), vomiting (68-84%), abdominal pain (46-90%), early satiety (60-86%), postprandial fullness, bloating, and, in severe cases, weight loss. The vomitus may contain food ingested several hours previously.
The predominant symptom may vary based on the underlying etiology. In a retrospective study that included 416 patients with gastroparesis, patients with idiopathic gastroparesis reported more early satiety, postprandial fullness, and abdominal pain as compared with patients with diabetic gastroparesis. In contrast, patients with diabetic gastroparesis had more severe retching and vomiting.
Bloating is common in gastroparesis and is severe in many individuals. In one study of 335 individuals with gastroparesis, bloating was at least mild in 76% and severe in 41% of individuals.
While abdominal pain is a frequent symptom in patients with gastroparesis, it is rarely the predominant symptom (18%). In patients whose predominant symptom is abdominal pain, other causes should be sought. The pain is usually localized to the upper abdomen and is often described as burning, vague, or crampy. Approximately 60% report exacerbation of pain after eating. In one case series, pain interfered with sleep in 80% of patients. However, the severity of abdominal pain did not correlate with a delay in gastric emptying, suggesting that the cause of pain in this tertiary referral cohort may not have been gastroparesis.]

How long do you continue proton pump inhibitor therapy that has failed to alleviate GERD symptoms?
3-4 weeks
[Failure of PPI requires follow-up diagnostic studies]
[UpToDate:We recommend an upper endoscopy in patients with typical GERD symptoms that persist despite a therapeutic trial of four to eight weeks of twice-daily PPI therapy.
While the definition is controversial, patients who fail to respond to once-daily PPI therapy are considered to have refractory GERD and should be referred to a gastroenterologist. Expert opinion suggests that twice-daily PPI therapy should be used to improve symptom relief in patients with esophageal GERD symptoms with an unsatisfactory response to once-daily dosing. In contrast, metoclopramide as monotherapy or adjunctive therapy is not recommended in patients with esophageal or suspected extraesophageal GERD symptoms. The evaluation and management of refractory GERD and the role of surgery in patients with refractory GERD are discussed separately.]

What is the potential advantage of the transhiatal approach to esophagectomy?
May have decreased mortality from esophageal leaks with cervical anastomosis
[UpToDate: In the largest prospective database series of 2007 patients, the in-hospital mortality rate decreased in the 1998-2006 cohort (n = 944 patients) compared with the 1976-1998 cohort (1% vs 4%). In addition, the anastomotic leak rate was also lower in the 1998-2006 cohort (9% vs 14%). Other postoperative complications included atelectasis and pneumonia (2%), and intrathoracic hemorrhage, recurrent laryngeal nerve (RLN) paralysis, chylothorax, and tracheal laceration in < 1% each. Similar results have been noted in other large series.
Disadvantages include the inability to perform a full thoracic lymphadenectomy and lack of visualization of the midthoracic dissection.]
What type of hiatal hernia is characterized as a mixed or combined hernia with both sliding characteristics and paraesophageal characteristics?
Type III
[UpToDate: Type III hernias have elements of both types I (sliding) and II (paraesophageal) hernias and are characterized by both the GE junction and the fundus herniating through the hiatus. The fundus lies above the GE junction.

What are 5 risk factors for esophageal cancer?
- ETOH
- Tobacco
- Achalasia
- Caustic injury
- Nitrosamines
[UpToDate: The major risk factors for SCC of the esophagus in the United States are smoking and alcohol consumption but other risk factors may be important in specific regions of the world. The major risk factors for SCC in the “esophageal cancer belt” of Iran and Asia are not well understood, but are thought to include poor nutritional status, low intake of fruits and vegetables, and drinking beverages at high temperatures.
The major risk factors for adenocarcinoma of the esophagus are Barrett’s esophagus, gastroesophageal reflux disease, smoking, and a high body mass index.]

Hyperemia of the esophagus following caustic injury is characteristic of what grade of burn?
Grade 1 burn
[UpToDate: A grading system for esophageal injury to predict subsequent clinical outcome has been developed based upon a study of 81 patients with corrosive ingestion.
- Grade 0 – Normal
- Grade 1 – Mucosal edema and hyperemia
- Grade 2A – Superficial ulcers, bleeding, exudates
- Grade 2B – Deep focal or circumferential ulcers
- Grade 3A – Focal necrosis
- Grade 3B – Extensive necrosis
A modification of the burn classification, this system is widely used although its validity has yet to be confirmed in other prospective studies. The following correlations between endoscopic grading and prognosis have been observed:
Patients with grades 1 and 2A have an excellent prognosis without significant acute morbidity or subsequent stricture formation.
Patients with grades 2B and 3A develop strictures in 70-100% of cases.
Grade 3B carries a 65% early mortality and the need for esophageal resection with colonic or jejunal interposition in most cases. In a large retrospective study, patients with grade 3B mucosal injuries were at greater risk of prolonged hospital stay (odds ration [OR] 2.4), ICU admission (OR 10.8), and gastrointestinal and systemic complications (OR 4.2 and 4.1, respectively).
A retrospective series with 49 patients with caustic ingestion graded the degree of esophageal damage using a scoring system based on the extent of esophageal wall edema and the adjacent tissue damage on thoracoabdominal computed tomography (CT) scans. Damage to the esophagus was correlated with the presence of esophageal strictures when the extent of damage approached grades III and IV. The CT grading system resulted in a slightly larger area under the receiver operating characteristic curve (0.90) for predicting strictures compared with the endoscopic grading system (0.79).]
What are the findings on manometry in a patient with achalasia?
- Increased lower esophageal sphincter (LES) pressure
- Incomplete LES relaxation
- No peristalsis
[UpToDate: Aperistalsis in the distal two-thirds of the esophagus and incomplete LES relaxation are diagnostic findings of achalasia on conventional manometry. Elevated resting LES pressure is supportive of the diagnosis of achalasia, but is not always present and is not diagnostic.
Typical conventional manometric findings:
- Aperistalsis in the distal two-thirds of the esophagus – In patients with achalasia, aperistalsis is seen in the smooth muscle portion of the body of the esophagus. Swallows may elicit no esophageal contraction or may be followed by simultaneous contractions with amplitudes <40 mmHg.
- Incomplete LES relaxation – Incomplete LES relaxation distinguishes achalasia from other disorders associated with aperistalsis. In normal individuals, there is complete relaxation of the LES after a swallow (to a level <8 mmHg above gastric pressure). In contrast, in patients with achalasia, LES relaxation in response to a swallow may be incomplete or absent with a mean swallow-induced fall in resting LES pressure to a nadir value of >8 mmHg above gastric pressure.
- Elevated resting LES pressure – Loss of inhibitory neurons in patients with achalasia can cause resting LES pressures to rise to hypertensive levels (above 45 mmHg).
Atypical manometric findings – A number of atypical manometric findings have been reported in patients with achalasia, including achalasia with preserved peristalsis, cases with occasional complete or partial LES relaxation, and vigorous achalasia. Vigorous achalasia is an outdated term that has been used for patients who have simultaneous esophageal body contractions with amplitudes >40 mmHg in the presence of a non-relaxing LES on conventional manometry, sometimes associated with spastic esophageal activity on barium swallow. Preserved peristalsis with esophageal contractions >40 mmHg also has been described in patients with vigorous achalasia. The distinction between vigorous and classic achalasia appears to have little clinical significance. Some patients diagnosed with vigorous achalasia by conventional manometry have type III achalasia by high-resolution manometry (HRM).]

From which side is the appropriate surgical approach for the cervical esophagus?
Left
[UpToDate: A left neck exposure is preferred for the esophagogastric anastomosis, since this approach reduces the risk of injury to the recurrent laryngeal nerve (RLN). The left RLN recurs lower (around the aortic arch) than the right RLN, which recurs around the subclavian artery and is therefore more likely to be injured from a right neck approach.]

Deep ulcers, charring, and lumen narrowing of the esophagus following caustic injury is characteristic of what kind of burn?
Grade 3 burn
[UpToDate: A grading system for esophageal injury to predict subsequent clinical outcome has been developed based upon a study of 81 patients with corrosive ingestion.
- Grade 0 – Normal
- Grade 1 – Mucosal edema and hyperemia
- Grade 2A – Superficial ulcers, bleeding, exudates
- Grade 2B – Deep focal or circumferential ulcers
- Grade 3A – Focal necrosis
- Grade 3B – Extensive necrosis
A modification of the burn classification, this system is widely used although its validity has yet to be confirmed in other prospective studies. The following correlations between endoscopic grading and prognosis have been observed:
Patients with grades 1 and 2A have an excellent prognosis without significant acute morbidity or subsequent stricture formation.
Patients with grades 2B and 3A develop strictures in 70-100% of cases.
Grade 3B carries a 65% early mortality and the need for esophageal resection with colonic or jejunal interposition in most cases. In a large retrospective study, patients with grade 3B mucosal injuries were at greater risk of prolonged hospital stay (odds ration [OR] 2.4), ICU admission (OR 10.8), and gastrointestinal and systemic complications (OR 4.2 and 4.1, respectively).
A retrospective series with 49 patients with caustic ingestion graded the degree of esophageal damage using a scoring system based on the extent of esophageal wall edema and the adjacent tissue damage on thoracoabdominal computed tomography (CT) scans. Damage to the esophagus was correlated with the presence of esophageal strictures when the extent of damage approached grades III and IV. The CT grading system resulted in a slightly larger area under the receiver operating characteristic curve (0.90) for predicting strictures compared with the endoscopic grading system (0.79).]
Which disease causes dysphagia and loss of lower esophageal sphincter tone with massive reflux and strictures?
Scleroderma
[UpToDate: Nearly 90% of patients with either subtype of SSc (diffuse cutaneous SSc [dcSSc] or limited cutaneous SSc [lcSSc]) have evidence of gastrointestinal involvement. Nearly half of these patients may have no symptoms. These issues are discussed in detail separately but will be briefly reviewed here.
Esophageal hypomotility and incompetence of the lower esophageal sphincter disease were the earliest described visceral manifestations of SSc. Symptoms principally result from chronic gastroesophageal reflux, with subsequent chronic esophagitis and stricture formation, Barrett’s esophagus, and pulmonary microaspiration.
Any part of the gastrointestinal tract from mouth to anus may be affected in SSc. Common symptoms of gastrointestinal involvement include dysphagia and choking, heartburn, hoarseness, cough after swallowing, bloating, alternating constipation and diarrhea, pseudo-obstruction and bacterial small bowel overgrowth with malabsorption, and fecal incontinence. Chronic gastroesophageal reflux and recurrent episodes of microaspiration may contribute to the development or progression of interstitial lung disease. Vascular ectasia (angiodysplasia) in the antrum of the stomach (“watermelon stomach”) is frequent and may be a cause of chronic gastrointestinal bleeding and anemia.]
How does one diagnose Boerhaave’s syndrome?
Gastrografin swallow
[UpToDate: Boerhaave syndrome is often diagnosed incidentally in a patient being evaluated for chest pain. The diagnosis of Boerhaave syndrome should be suspected in patients with severe chest, neck, or upper abdominal pain after an episode of severe retching and vomiting or other causes of increased intrathoracic pressure, and the presence of subcutaneous emphysema on physical exam. While thoracic and cervical radiography can be supportive of the diagnosis, the diagnosis is established by contrast esophagram or computed tomography (CT) scan.
Delay in the diagnosis is associated with a higher risk of complications and mortality, which ranges between 16% and 51%]

Manometry showing high-amplitude peristaltic contractions with normal relaxation of the lower esophageal sphincter is characteristic of what?
Nutcracker esophagus
[Nutcracker esophagus, or Hypertensive peristalsis, is a disorder of the movement of the esophagus characterized by contractions in the smooth muscle of the esophagus in a normal sequence but at an excessive amplitude or duration.]
[UpToDate: Nutcracker esophagus is characterized by normal sequential contractions in the smooth muscle esophagus of excessive amplitude or duration. On conventional manometry, nutcracker esophagus is defined by high amplitude peristaltic contractions in the distal 10 cm of the esophagus, with average distal esophageal peristaltic pressures exceeding 220 mmHg after 10 5 mL liquid swallows. On HRM with EPT, these high pressure contractions are identified by distal contractile integral (DCI) >8000x mmHgscm. Other terms for hypertensive peristalsis include “spastic nutcracker” or “jackhammer esophagus”.
Nutcracker esophagus may overlap with other esophageal motility disorders. Many patients with nutcracker esophagus also have a hypertensive or poorly relaxing LES. One study using ambulatory 24-hour esophageal manometry found that patterns of DES or nutcracker esophagus on stationary manometry frequently interchanged during episodes of chest pain.]

Manometry showing strong non-peristaltic unorganized contractions and normal relaxation of the lower esophageal sphincter is characteristic of what?
Diffuse esophageal spasm
[UpToDate: Patients with diffuse (distal) esophageal spasm (DES) are symptomatic and present with dysphagia for solids and liquids. Patients have esophageal dysphagia, which is characterized by difficulty swallowing several seconds after initiating a swallow and a sensation of food getting stuck in the esophagus. The dysphagia may occur in association with retrosternal chest pain. In some cases, patients have symptoms of heartburn or regurgitation. In contrast with DES, only a small proportion of patients with nutcracker esophagus and hypertensive lower esophageal sphincter (LES) are symptomatic. In all three disorders, symptoms do not necessarily correlate with manometric abnormalities and may be due to concurrent gastroesophageal reflux disease (GERD) or heightened visceral sensitivity.
DES is characterized by increased simultaneous contractions in the distal esophagus. On conventional manometry, DES is defined by 20% or more simultaneous contractions (with amplitude >30 mmHg). On high resolution manometry (HRM) with esophageal pressure topography (EPT), DES is defined by ≥20% premature contractions (distal latency <4.5 seconds).
It is important to note that DES is intermittent, and manometric findings may be seen with only some of a series of test swallows or only on some days of testing. Patients with DES may also have a variety of other nonspecific manometric findings, including repetitive and prolonged duration contractions. Although most patients with DES usually have normal relaxation of the LES, approximately one-third of patients may have high resting pressure or incomplete relaxation. Patients with DES who present with chest pain have higher amplitudes and better transit of swallowed boluses on impedance testing as compared with those who present with dysphagia.]

Where is esophageal perforation most likely to occur in patients with Boerhaave’s syndrome?
Left lateral wall of esophagus, 3-5 cm above the GE junction
[UpToDate: Boerhaave syndrome usually occurs in patients with a normal underlying esophagus. However, a subset of patients with Boerhaave syndrome has underlying eosinophilic esophagitis, medication-induced esophagitis, Barrett’s or infectious ulcers. Sudden increase in intraesophageal pressure combined with negative intrathoracic pressure such as that associated with severe straining or vomiting, and less frequently with childbirth, seizure, prolonged coughing or laughing, or weightlifting, results in a longitudinal esophageal perforation.
The esophageal perforation usually involves the left posterolateral aspect of the distal intrathoracic esophagus and extends for several centimeters. However, the rupture can occur in the cervical or intra-abdominal esophagus. Rupture of the intrathoracic esophagus results in contamination of the mediastinal cavity with gastric contents. This leads to chemical mediastinitis with mediastinal emphysema and inflammation, and subsequently bacterial infection and mediastinal necrosis. Rupture of the overlying pleura by mediastinal inflammation or by the initial perforation directly contaminates the pleural cavity, and pleural effusion results. Although pericardial tamponade and infected pericardial effusions due to Boerhaave syndrome have been reported, they are rare. If untreated, sepsis and organ failure result.
Effort rupture of the cervical esophagus leads to a localized cervical perforation and has a more benign course, as the spread of contamination to the mediastinum through the retroesophageal space is slow and attachments of the esophagus to the prevertebral fascia limit the lateral dissemination of esophageal flora.]

What is the treatment for esophageal manifestations of scleroderma?
Esophagectomy (if severe)
[UpToDate: We manage esophageal disease with a primary focus on the amelioration of reflux, hypomotility, and the symptoms of strictures; oral and esophageal candidiasis is treated with antifungal agents. We treat reflux with both lifestyle modifications, such as bed elevation and avoidance of late meals, and antisecretory agents, usually a proton pump inhibitor.
In patients with hypomotility, we use prokinetic drugs, such as cisapride or metoclopramide, and avoid nonsteroidal antiinflammatory drugs (NSAIDs) or calcium channel blockers, if possible. Coadministration of cisapride with erythromycin, clarithromycin, or imidazoles should be avoided because of potentially fatal drug interactions. Treatment for esophageal strictures involves use of both proton pump inhibitors and dilatation when needed.]

What procedure must accompany an esophagectomy?
Pyloromyotomy
[UpToDate: The role of a pyloroplasty or pyloromyotomy to reduce the risk of gastric outlet obstruction following a gastric pull-up procedure has been challenged by prospective studies and randomized trials, including:
- A prospective study of 242 patients undergoing an esophagectomy with gastric conduit found that patients with a pyloromyotomy (n = 159) did not have significantly lower rates of gastric outlet obstruction compared with those without a pyloromyotomy (9.6% vs 18.2%). In addition, there was no significant difference for rates of pneumonia or mortality (27.7% vs 19.5%, and 2.4% vs 2.5%, respectively). Management with pyloric dilation was effective in relieving symptoms in approximately 97% of symptomatic patients.
- A meta-analysis of nine trials and 553 esophagectomy patients randomized to pyloromyotomy versus none found a lower risk of gastric outlet obstruction for patients treated with a pyloromyotomy (OR 0.18, 0.03-0.97, p<0.046) [144]. There was no difference for operative mortality, esophagogastric anastomotic leaks, pulmonary morbidity, or fatal pulmonary aspiration.]

The upper 1/3 of the esophagus is composed of what type of muscle?
Striated muscle

Where are the incisions made in the 3-hole approach to esophagectomy?
Abdominal, thoracic, and cervical incisions
[UpToDate: The tri-incisional esophagectomy combines the transhiatal and transthoracic approaches into a transthoracic total esophagectomy with a thoracic lymphadenectomy and cervical esophagogastric anastomosis. The three-incisional technique allows the surgeon to perform a complete two-field (mediastinal and upper abdominal) lymphadenectomy under direct vision and a cervical esophagogastric anastomosis. We prefer a thorascopic approach to the chest rather than a thoracotomy to minimize the risk of respiratory complications.
Thoracotomy – A right posterolateral thoracotomy or a thoracoscopy is performed first to assess resectability and exclude local invasion of contiguous structures. An en bloc resection is performed that includes the esophagus and mediastinal and upper abdominal lymph nodes, including the right paratracheal, subcarinal, periesophageal and celiac axis lymph nodes.
Laparotomy – The abdomen is explored to exclude metastatic disease, and the stomach is mobilized in preparation for the construction of the gastric conduit.
Neck incision – A left neck exposure is preferred for the esophagogastric anastomosis, since this approach reduces the risk of injury to the recurrent laryngeal nerve (RLN). The left RLN recurs lower (around the aortic arch) than the right RLN, which recurs around the subclavian artery and is therefore more likely to be injured from a right neck approach.]
Where are the incisions made in the Ivor Lewis approach to esophagectomy?
Abdominal incision and a right thoracotomy
[UpToDate: The Ivor-Lewis transthoracic esophagectomy can be used to resect cancers in the lower third of the esophagus but is not the optimal approach for cancers located in the middle third because of the limited proximal margin that can be achieved. This procedure combines a laparotomy with a right thoracotomy and an intrathoracic esophagogastric anastomosis. This approach permits direct visualization of the thoracic esophagus and allows the surgeon to perform a full thoracic lymphadenectomy. We prefer a minimally invasive Ivor-Lewis approach to a thoracotomy.
A modification of the Ivor-Lewis transthoracic esophagectomy includes a left thoracoabdominal incision with a gastric pull-up and an esophagogastric anastomosis in the left chest. This approach is most useful for tumors involving the gastroesophageal junction. Only one incision is required, but disadvantages include a high incidence of complications such as postoperative reflux and limitation of the proximal esophageal margin by the aortic arch.]























































