Cardiac, Thoracic, and Vascular: Esophagus Flashcards
Esophagus: Anatomy and Physiology (Part 1)
- The esophagus is a muscular tube that functions pri-
marily as a conduit for transporting ingested solids and
liquids from the mouth into the intra-abdominal gas-
trointestinal tract. It extends from the pharynx to the
stomach, traversing the posterior mediastinum, and is
bounded posteriorly by the vertebral column and
thoracic duct, anteriorly by the trachea, laterally by
the pleura, and on the left by the aorta (Figs. 19-1 and
19-2). It begins at the cricoid cartilage in the neck and
courses downward to the left, then to the right, and back
to the left to pierce the diaphragm and join the cardia
of the stomach. The intra-abdominal portion of the
esophagus measures
3 cm. The upper one third of the
esophageal musculature is skeletal, whereas the lower
two thirds is smooth muscle. Unlike the intra-abdomi-
nally located stomach, small intestine, and colon, there is
no true serosal layer covering the esophagus.
The vagus nerves form a plexus around the esopha-
gus, which condenses distally to form two trunks on the
lateral esophagus. These trunks, in turn, rotate so that
the left trunk moves anteriorly, whereas the right trunk
moves posteriorly.
Esophagus: Anatomy and Physiology (Part 2)
- The esophageal mucosa is lined by squamous
epithelium that becomes columnar near the gastro-
esophageal junction. The next layer encountered
moving radially outward is the submucosa, which
contains the submucous (Meissner) plexus. Next are
two muscular layers, the inner circular muscle layer
and the outer longitudinal muscle layer. Sandwiched
in between these two muscular layers is the myen-
teric (Auerbach) plexus.
The arterial supply of the esophagus involves vessels
from the neck, chest, and abdomen. The superior and
inferior thyroid arteries supply the upper esophagus,
whereas the intercostals, left gastric, and phrenic arteries
supply the lower esophagus. Venous drainage of the
upper esophagus is into the inferior thyroid and verte-
bral veins, whereas the mid and lower esophagus drains
into the azygous, hemiazygous, and left gastric veins.
Submucosal veins can become engorged in patients with
portal hypertension, causing varices and potentially life-
threatening bleeding. Lymphatics drain into cervical,
mediastinal, celiac, and gastric nodes. Innervation is from
the vagus, cervical sympathetic ganglion, splanchnic gan-
glion, and celiac ganglion. These nerves are responsible
for esophageal motility.
Peristasis conveys food into the stomach. Gastric
reflux is prevented by increased tone in the lower
portion of the esophagus; there is no true sphincter.
Air ingestion is prevented by resting tone in the
upper esophagus.
Esophageal Neoplasms: Pathology
- Esophageal neoplasms are almost always malignant.
Benign tumors account for fewer than 1% of cases and
are usually leiomyomas or congenital cysts. Symptomatic
benign esophageal neoplasms are treated with local
resection or enucleation. Most malignant esophageal
neoplasms seen worldwide are of squamous cell his-
tologic type, whereas adenocarcinoma histology pre-
dominates in the United States and other industrial-
ized nations. Most cases of adenocarcinoma arise in
the distal third or gastroesophageal junction (80%).
Metastases are usually to liver, lungs, and bones, with
at least 35% of patients with distant metastases at the
time of diagnosis. Early-stage cancers are usually diag-
nosed only incidentally or else discovered on screen-
ing studies. Prognosis is poor, with an overall 5-year
survival rate of only 5%.
Esophageal Neoplasms: Pathogenesis
- Mucosal insult seems to be a common pathway toward
the genesis of esophageal cancer. Chronic ingestion
of extremely hot liquids, esophageal burns from acid
or base ingestions, radiation-induced esophagitis,
and reflux esophagitis are all implicated in causing
esophageal cancer. Alcohol, smoking, nitrosamines,
and malnutrition/vitamin deficiency also play a role
in cancer development. Barrett esophagus, which occurs
when the normal squamous epithelium becomes colum-
nar in response to injury from acid reflux, is considered
a premalignant lesion. Approximately 10% of patients
with Barrett esophagus will develop adenocarcinoma.
In patients with achalasia, approximately 6% will
develop squamous cell carcinoma of the esophagus.
Esophageal Neoplasms: Epidemiology
- The incidence of esophageal cancer varies according to
the presence of the etiologic factors described previ-
ously. For example, in places with high soil nitrosamine
content, the prevalence of esophageal cancer is almost
1% of adults. In the United States, the incidence of
esophageal cancer is four in 100,000 White men and
12 in 100,000 Black men. It is most commonly a dis-
ease of men between 50 and 70 years of age.
Esophageal Neoplasms: History
- At the time of diagnosis, most patients have advanced
disease and are not surgical candidates for curative resec-
tion. The lack of a serosal lining and the rich submucosal
lymphatic network of the esophagus allows early exten-
sion of tumor into adjacent mediastinal structures as
well as early local lymph node spread. Approximately
75% of patients have mediastinal or extrathoracic lymph
node metastases at the time of diagnosis.
The classic presentation of distal esophageal adeno-
carcinoma is an older man with a history of gastro-
esophageal reflux disease complaining of progressive
dysphagia to solids initially, and then to liquids. Typically,
patients feel well and have no other symptoms. Some
report noting mild weight loss, more often related to
diminished caloric intake resulting from obstructive
symptoms than to cachexia from metastatic disease.
Chest pain and odynophagia (pain with swallowing)
may also occur. Invasion of a recurrent laryngeal nerve
may cause hoarseness from vocal cord paralysis.
Patients with esophageal squamous cell carcinoma
often have a history of heavy alcohol and tobacco use
and present with more pronounced symptoms owing
to more advanced disease.
Esophageal Neoplasms: Physical Examination
- Signs are nonspecific, and patients appear well unless
significant metastatic disease is present. Supraclavicular
lymphadenopathy at presentation is rare.
Esophageal Neoplasms: Diagnostic Evaluation
- Barium esophagogram detects malignant lesions in
96% of patients. Findings range from small mucosal
defects to “apple core” lesions to complete obstruc-
tion (Fig. 19-3). This is usually the initial study for
the evaluation of new onset dysphagia. Definitive
diagnosis of cancer requires confirmation by flexible
endoscopy with tissue biopsy. If Barrett esophagitis
alone is noted, the extent of disease can be deter-
mined and biopsies performed to look for dysplasia or
carcinoma in situ.
To determine the stage of the primary tumor (T) and
regional lymph node status (N), endoscopic ultrasound
EUS) is used. Ultrasound is best for evaluating local
staging: the intramural extent of the tumor as well as
assessing for lymph node enlargement or abnormality.
Ultrasound depicts the normal five layers of the esoph-
agus and can accurately determine the T status in 85%
to 90% of patients. Fine-needle aspiration biopsy of
abnormal-appearing lymph nodes under ultrasound
guidance may be performed.
Evaluation of regional and distant disease is best
done by computed tomography (CT) scan and positron
emission tomography scan. CT scanning should be
performed first after initial diagnosis, because lung and
liver metastases are often detected. If CT is negative
for metastases, then EUS is performed. Combined
preoperative CT and EUS have an accuracy rate of
86% for TNM staging.
Esophageal Neoplasms: Staging
- The TNM system is used for staging esophageal cancer.
Clinical stage (cTNM) is determined by evaluation of
all information derived from physical examination,
imaging studies, endoscopy, biopsy, and occasionally
laparoscopy or thoracoscopy. Once the clinical stage is
determined, rational treatment plans can be proposed
to the patient (Table 19-1 and Fig. 19-4).
Esophageal Neoplasms: Treatment (Part 1)
- Because there is no serosal layer covering the esopha-
gus, disease is often locally advanced or metastatic on
presentation, leading to poor overall survival statistics.
Surgical cure rates are 20% to 30% at best. The goals
of surgical treatment are removal of the tumor and
regional lymph nodes followed by re-establishment of
gastrointestinal tract continuity. For early-stage disease,
esophagectomy provides the possibility of cure.
Preoperatively, induction chemoradiotherapy may be
administered, especially to downstage patients with
resectable bulky tumors. Some evidence has shown that
induction chemotherapy and radiotherapy preopera-
tively, followed by surgery, can improve long-term sur-
vival, but this remains an area of controversy. The
extent of lymphadenectomy is also an area of ongoing
controversy.
Esophageal Neoplasms: Treatment (Part 2)
- Various operations with varying degrees of invasive-
ness have been developed for treating esophageal can-
cer. In deciding which procedure to perform, the sur-
geon must take into consideration the location of the
tumor, the proposed esophageal substitute, and the
physical condition and body habitus of the patient.
Generally, the most common surgical approaches are
transthoracic (thoracotomy) and tran
shiatal without thoracotomy. Incisions may be required in the neck, chest, and abdomen.
Esophageal Neoplasms: Treatment (Part 3)
- The most common transthoracic esophagectomy is
one called the Ivor Lewis esophagectomy, named after
the distinguished Welsh surgeon who developed the
approach. In brief, it involves upper midline laparot-omy
with mobilization of the stomach and is followed by
right thoracotomy with esophageal resection and anasto-
mosis. It is useful for patients with tumors of the middle
and lower esophagus. For tumors of the upper esophagus,
many surgeons use a modified approach, called the
McKeown modification, which involves additional
intrathoracic esophageal mobilization and anastomosis in
the right neck through a separate cervical incision (three-
hole technique). The tubularized stomach is used as the
esophageal substitute in most cases. Other possible sub-
stitutes are the colon and small bowel (Fig. 19-5).
Esophageal Neoplasms: Treatment (Part 4)
- Esophagectomy without thoracotomy is termed
the transhiatal approach. This technique uses laparot-
omy for gastric and esophageal mobilization, fol-
lowed by left cervical incision for the anastomosis.
The major benefit of this approach is avoiding the
complications that arise from thoracotomy.
Although open surgical approaches remain the
standard for esophagectomy, recent advances in mini-
mally invasive surgery have allowed esophagectomy to
be performed using laparoscopic and thoracoscopic
techniques. A cervical incision is also used (Fig. 19-6).
This is a complex and challenging procedure that has
a steep learning curve. Early results of laparoscopic
esophagectomy seem to compare favorably with open
surgery, but long-term data are presently not available.
Achalasia: Pathophysiology
- The term “achalasia” is derived from the Greek, mean-
ing “failure to relax.” It is defined as absence of peri-
stalsis in the smooth muscle of the distal esophagus
and failure of the lower esophageal sphincter (LES) to
relax with swallowing. The exact cause of primary
achalasia is not well understood, but studies have shown
abnormalities in the myenteric plexus (Auerbach).
Histologic evidence shows inflammation, fibrosis, and
loss of ganglion cells. Possible causes are infectious
(neurotropic virus) or degenerative.
In South and Central America, the most common
cause of secondary achalasia is Chagas disease
(American trypanosomiasis).
Achalasia: Epidemiology
- Achalasia is the most common disorder of esophageal
motility but is actually rare, with an incidence of 0.5 per
100,000. Men and women are equally affected. Patients
usually present between 20 and 50 years of age.
Achalasia: Treatment
- There is no cure for achalasia, given the still uneluci-
dated underlying process that causes esophageal neu-
ral pathology. Treatment is focused on relief of symp-
toms (dysphagia) caused by achalasia.
Medical treatment consists mainly of pneumatic
balloon dilatation (Fig. 19-7) of the lower esophageal
sphincter to reduce outflow obstruction and facilitate
gravity drainage. This technique is minimally invasive,
has good initial results, and can be repeated.
However, it carries the risk of esophageal perforation
and over the long term has inferior results when com-
pared with surgical therapy. Another medical treat-
ment is LES relaxation by paralysis achieved by endo-
scopic injections of botulinum toxin (Botox). This
may be an option for frail, high-risk patients, as all
patients experience symptomatic relapse.
Surgical therapy by esophageal myotomy (Heller
myotomy) is the definitive treatment for achalasia.
The goal of myotomy is to reduce LES pressure to
facilitate gravity drainage while also performing a
partial fundoplication to ensure a degree of gastro-
esophageal reflux control. The procedure is performed
using the laparoscopic approach, with low morbidity.
Longitudinal separation of the esophageal muscula-
ture is carried from the distal esophagus onto the
proximal stomach, and partial fundoplication (Dor or
Toupet wrap) completes the procedure. Myotomy
can also be performed through the chest by thora-
coscopy or thoracotomy, but with greater morbidity.
Surgical therapy provides superior long-term results
over medical interventions.
