ch 30 Esophagus Flashcards
How might scintigraphy be used in esophageal diagnostics?
can be used to quantify motility and transit time, and to diagnose gastroesophageal reflux
Which muscle determines the start of the esophagus, i.e. is the cranial esophageal sphincter?
cricopharyngeal sphincter muscle = cricopharyngeus + thyropharyngeus
Which muscles are closely associated with the dorsal esophagus in the cranial thorax?
longus colli
longus capitis
The esophagus is to the left/right of the trachea at the thoracic inlet.
left
what are the layers of the esophagus?
fibrous, muscular, submucosa, mucosa
what kind of muscle is the feline esophagus?
cranial 2/3: striated
caudal 1/3: smooth - oblique arrangement /herringbone pattern
what does the canine esophageal mucosa look like?
longitudinal folds
what kind of muscle is the canine esophagus?
striated
what makes up the caudal esophageal sphincter?
what artery supplies the cranial 2/3 thoracic esophagus?
bronchoesophageal
blood supply of the esophagus?
cervical: thyroid arteries
cranial 2/3 thoracic: bronchoesophageal
caudal 1/3 thoracic: intercostal and/or esophageal branches of aorta
terminal portion: left gastric
what artery supplies the cervical esophagus?
thyroid
what artery supplies the caudal 1/3 thoracic esophagus?
intercostal and/or esophageal branches of aorta
what artery supplies the terminal esophagus?
left gastric
Which veins drain the thoracic part of the esophagus?
azygous & left gastric
lymphatics of the esophagus
med retropharyngeal
deep cervical
cran mediastinal
bronchial
portal, splenic, gastric
esophageal innervation
CN 5, 7, 9, 10, 12
in which projection can the normal caudal thoracic esophagus be visualised?
left lateral
rare in RL
When and where can gas accumulate focally in the esophagus (under normal circumstances)?
Gas can accumulate focally in the esophagus in animals that are excited, sedated, and dyspneic or under general anesthesia; this gas accumulation is usually minimal, and the most common location for this to occur is just cranial to the tracheal bifurcation
What is the tracheal stripe sign?
Summation of ventral esophageal wall with dorsal tracheal wall, visible due to gas in the esophagus
Typical signalment for redundant esophagus?
Young or short-necked brachycephalic dogs
Which type of contrast medium is contraindicated for patients with increased risk of aspiration?
Barium paste; may cause airway obstruction
What is a potential complication of contrast esophagrams?
Barium aspiration; small amount usually asymptomatic, but pneumonia and lung granulomas can occur.
How long does it take for barium to be cleared if it reaches the alveoli?
It may remain there forever/permanently.
It may also be found in the tracheobronchial and mediastinal lymph nodes permanently.
Are esophograms performed conscious, sedate, or under GA?
conscious
During an esophogram, how much contrast should be left in the oral cavity and pharynx after swallowing?
None
Which contrast is the best for suspected esophageal perforation?
Non-ionic (low osmolar)/ iohexol or iopamidol
What is the disadvantage of ionic (hyperosmolar) contrast medium?
can induce pulmonary edema if aspirated. do not use!
What are 2 ionic (hyperosmolar) contrast mediums?
diatrizoate sodium, meglumine
What is the advantage of barium sulfate paste?
Adheres to the esophageal mucosa and is best for diagnosing esophagitis, mucosal irregularities, or infiltration
What is the disadvantage of barium sulfate liquid?
It does not adhere well to mucosa (to show mucosal disease), and is contraindicated if perforation is suspected
What is the advantage of barium sulfate?
Relatively safe if aspirated, may pass through incomplete obstructions or strictures
How many mLs of barium (60%) should you administer to a small dog / large dog / cat, for a static barium esophagram?
small dog (15ml), large dog (20-30ml), cat (5-7 ml)
What percentage barium sulfate is used?
60%
What happens during the cricopharyngeal phase of swallowing?
Which CN?
- relaxation of cricopharyngeal sphincter during pharyngeal contraction, which propels the bolus aborally (CN IX, X)
What are the control mechanisms for the oral phase of swallowing?
Hyoid apparatus
Tongue
Nerves: Facial, Vagus, Hypoglossal
How much dry kibble with how much barium suspension, for a barium meal esophagram?
1 cup dry kibble + 20 mL barium
1/2 for cats
Which phases of swallowing does the facial nerve control?
Oral and Pharyngeal
What are the 5 phases of swallowing?
OPCEG
Oral
Pharyngeal
Cricopharyngeal
Esophageal
Gastric
When should secondary peristalsis occur?
2 to 4 seconds; in the esophageal phase
What happens during the oral phase of swallowing?
The liquid or food bolus is formed, and reflex pharyngeal peristalsis starts.
what happens during the pharyngeal phase of swallowing?
- craniodorsal movement of the hyoid (caused by pharyngeal contraction)
- the bolus enters the laryngopharynx
- the glottis closes the entrance to the trachea
Which frame rate is recommended for fluoroscopic examination of dysphagia?
30 - 60 fps
Which 4 assessments during fluoroscopy will help assess and categorise dysphagia as oral / pharyngeal / cricopharyngeal in origin?
1) bolus formation
2) pharyngeal and tongue movement
3) pharyngeal clearing of barium
4) cricopharyngeal sphincter function
Which phase of swallowing is voluntary?
The oral phase
Normal cricopharyngeal phase of swallowing. The bolus passes through the cricopharyngeal sphincter into the cranial aspect of the esophagus (large white arrow), and the cricopharyngeal sphincter (small white arrows) is open momentarily.
What characterises oral dysphagia?
Dropping food
salivating / drooling
failure to form a bolus (thus no swallowing reflex is induced)
Which phase?
Pharyngeal
Normal esophageal phase of swallowing. A tight bolus with a convex cranial border that tapers caudally is present in the cranial aspect of the esophagus.
Is the pharyngeal constriction ratio higher or lower in cricopharyngeal dysphagia?
higher
Which pharyngeal disorder could be misinterpreted as a cricopharyngeal disorder?
small sphincter opening
what is the discerning factor between pharyngeal and cricopharyngeal dysphagia?
time to opening of the cricopharyngeal sphincter - this is significantly shorter in pharyngeal dysphagia
What is the pharyngeal constriction ratio?
pharyngeal area at max contraction / pharyngeal area at rest
In which phase dysphagia (pharyngeal or cricopharyngeal) is the time to opening of the cricopharyngeal sphincter, shorter?
pharyngeal
Toy breeds are associated with which type of dysphagia?
Cricopharyngeal achalasia
Which type/breed of dog is associated with cricopharyngeal achalasia?
Toy breeds
What are the 2 types of cricopharyngeal dysphagia?
achalasia or dyssynchrony
what is cricopharyngeal achalasia?
failure of the CP sphincter to open fully
what is cricopharyngeal dyssynchrony?
failure of the CP sphincter to open at the appropriate time
In which dysphagia(s) can aspiration pneumonia be found?
pharyngeal (can), cricopharyngeal (common)
Gas in the cricopharyngeal sphincter and cranial cervical esophagus is often seen in which dysphagic condition?
Cricopharyngeal chalasia
What characterises cricopharyngeal dysphagia?
Failure of the cricopharyngeal sphincter to open fully or at the appropriate time (delayed or not synchronous)
Lack of coordination between pharyngeal contraction and opening of the sphincter
Esophagram findings of cricopharyngeal dysphagia
pharyngeal stasis of barium retention
CP muscle hypertrophy
retention of contrast in cervical esophagus
What is the difference in time from onset of swallowing (closure of the epiglottis) to opening of the CP sphincter in dogs with cricopharyngeal achalasia (vs. normal)?
Delayed 0.31s (vs .09) for liquids, 0.37s (vs. 0.10) for kibble
What is the difference in CP sphincter closure times in dogs with cricopharyngeal achalasia (vs. normal)?
Delayed
What is the difference in time to maximal pharyngeal contraction and epiglottic reopening in dogs with cricopharyngeal achalasia (vs. normal)?
No difference
Cricopharyngeal chalasia can be found in dogs with (condition)?
myastenia gravis
what is contraindicated with cricopharyngeal chalasia and how do you know when this is the case?
when there is air in the CP sphincter, barium administration is contraindicated due to increased risk of aspiration
What are the phases of esophageal swallowing?
primary and secondary peristalsis
Dysphagia is more common in dogs/cats.
dogs
what is the most common type of dysphagia in cats?
esophageal phase dysphagia
what are the most common causes of esophageal dysphagia in cats?
hiatal hernia, dysmotility and stricture
In which recumbency is cervical esophageal transit time the shortest?
Sternal
Which of the following differ between lateral and sternal recumbency?
A) pharyngeal constriction ratio
B) time to maximum pharyngeal contraction
C) time to cricopharyngeal sphincter opening
D) time to epiglottis reopening
E) cervical esophageal transit time
F) the percentage of primary waves with liquid and kibble
G) the percentage of secondary peristaltic waves
E) cervical esophageal transit time differs - it is much shorter in sternal recumbency.
F) The percentage of primary waves is much higher in sternal.
What qualifies as an abnormal primary wave (esophageal peristalsis)?
When the bolus is moved <5cm aborally
What are 2 markers of esophageal hypomotility?
retrograde flow of the bolus > 10 cm
prolonged esophageal transit time of > 5 sec
What qualifies as an abnormal secondary wave (esophageal peristalsis)?
When the bolus is retained in the esophagus after 2 consecutive swallows
Segmental (vs. generalised) dilation of the esophagus is likelier to be due to:
FISH RV
Foregin body
Infiltrative disease (neoplasia, inflammation)
Hiatal diseases
Segmental motor disease
Vascular ring anomaly
Redundant Esophagus
Retrograde flow of more than _____ cm is associated with hypomotility, as is prolonged esophageal transit time - more than ___ seconds.
10 (cm)
5 (s)
What is the impact of delayed maturation of the neuromuscular system on esophageal motility?
Esophageal dysmotility can be caused by delayed maturation, and spontaneous improvement after 1 year of age can occur because of maturation of the neuromuscular system
What is a described cause of feline megaesophagus?
Pylorospasm
Myastenia gravis does not cause:
A) Cricopharyngeal chalasia
B) Cricopharyngeal achalasia
C) Megaesophagus
D) Pharyngeal dysphagia
B
What is the difference between cricopharyngeal chalasia and achalasia?
In chalasia, the CP sphincter does not maintain positive resting pressure between swallows - it is relaxed / loose (greek khalan/khalasis). on XR, air in the sphincter, contraindicated to give barium and can be caused by myastenia gravis, radiation therapy, or CP myotomy.
In achalasia (lack of loosening/relaxation), there is incomplete opening of the CP sphincter. The cause is idiopathic.
What are the causes of megaesophagus?
Diseases of the :
- neuromuscular junction (MG)
- striated muscle (myositis)
- peripheral nerves (polyneuropathy)
- CNS (infl, tox, neoplastic)
Which section of the esophagus is more dilated with generalised megaesophagus, and why?
the thoracic segment of the esophagus is usually more severely dilatated than the cervical portion because of surrounding negative intrathoracic pressure
3 categories of esophageal hiatal disease
hernias (para/esophageal)
intussusception (gastro-esophageal)
reflux (gastro-esophageal)
Which are predisposing factors for acquired esophageal hernias?
weakness of the diaphragm
elevated abdominal pressure
upper airway obstruction
Which breed experiences congenital esophageal hernias?
Shar-Pei
In sliding esophageal hernia, the ______ and ________ move in and out of the caudal mediastinum through a ________ of the diaphragm
caudal esophageal sphincter, part of the gastric fundus
weakened esophageal hiatus
In __________________, the caudal esophageal sphincter and part of the gastric fundus move in and out of the caudal mediastinum through a weakened esophageal hiatus of the diaphragm
sliding esophageal hernia
_________ are caused by the fundus being herniated within the mediastinum alongside of the esophagus with the caudal esophageal sphincter remaining in the abdomen
Paraesophageal hernias
What is the difference between sliding esophageal, and paraesophageal hernias, and GE intussusception?
- in paraesophagealm the CES stays in the abdomen, and the fundus is herniated to the left of the esophagus
- in esophageal, they both move in and out of the mediastinum
- in intussusception, the CES also remains in the abdome, but the stomach everts into the esophagus. A feature that distinguishes gastroesophageal intussusception from a sliding or paraesopha-geal hernia is the sharply marginated cranial edge of the intussusceptum contrasted against a gas-filled esophageal lumen
Cause of gastro-esophageal intussuseception?
Gastroesophageal intussusception is often acquired and secondary to:
- esophageal dilatation
- previous surgery at the caudal esophageal sphincter resulting in chalasia
Redundant esophagus occurs in which breeds?
Redundant esophagus is often an incidental finding in young brachycephalic breeds, such as bulldogs and shar-peis.
What happens to contrast medium in a redundant esophagus after esophagram study?
It is usually temporary and will be cleared in subsequent radiographs.
What kind of function/motility does a redundant esophagus have?
The redundant segment typically has normal motility (seen on videofluoroscopy). Occasionally, there may be a significant motility disorder associated with this redundant region.
What is a possible explanation when you don’t see the longitudinal mucosal folds seen with barium study of the esophagus?
Inflammation can also obliterate the linear folds normally outlined with barium.
13-year- old miniature schnauzer. A compartmentalized, gas-filled structure is present in the caudodorsal thorax. This appearance could be caused by either a paraesophageal hernia or a sliding hiatal hernia. Ventrodorsal (VD) of the same dog. The gas-filled structure, which is the fundus (solid line), is to the left of midline and adjacent to the gas-filled and dilatated esophagus (dotted line), which takes on a tortuous course and is displaced to the right. The soft tissue mass in the left cranial thoracic quadrant is a thymoma.
Where do obstructive esophageal foreign bodies typically get lodged?
- thoracic inlet
- base of the heart
- just cranial to the diaphragm
- places where the esophagus is limited in its ability to distend
Why do obstructive esophageal foreign bodies get lodged where they do?
Because the esophagus has a limited ability to distend at these locations (thoracic inlet, base of the heart, just cranial to the diaphragm)
Where do non-obstructive, sharp esophageal foreign bodies tend to lodge?
in the pharyngeal region
Open safety pin obstructing the cervical esophagus caudal to the cricopharyngeal sphincter.
Contraindications for a barium swallow study (based on survey radiographs)?
Evidence of rupture/perforation:
- pneumothorax
- pneumomediastinum
- pleural effusion
How and when do patients present for esophageal disease due to vascular ring anomalies?
Regurgitation due to vascular ring anomalies presents at an early age in most instances; however, it can have late onset occurrence in both cats and dogs.
Under normal conditions, the aorta is derived from the __________ while the ___________ typically regresses.
left fourth aortic arch
right fourth aortic arch
What is a vascular ring anomaly?
Esophageal compression secondary to a vascular malformation
How many types of vascular ring anomaly are there?
7
Which vascular ring anomalies have a persistent right aortic arch?
type I, II, III
I-III: PRAA (persistent right aortic arch)
IV: double aortic arch
V - VII: L aortic arch with combinations of persistent R lig. arteriosum + R subclavian arteries
Which vascular ring anomalies have a double aortic arch?
type IV
I-III: PRAA (persistent right aortic arch)
IV: double aortic arch
V - VII: L aortic arch with combinations of persistent R lig. arteriosum + R subclavian arteries
What is a persistent R fourth aortic arch?
Development of the aortic arch from the RIGHT fourth aortic arch, with regression of the LEFT 4th aortic arch - this is the most common type of VRA that leads to esophageal entrapment.
In this configuration, the lig. arteriosum that connect the left-sided MPA and the right-sided aortic arch, compresses the esophagus against the trachea and heart base.
What is the most common type of vascular ring anomaly that causes entrapment of the esophagus?
Persistent R fourth aortic arch
Which part of the esophagus dilates with PR4AA?
cranial to the base of the heart
Lateral radiograph of a barium esophagram in an 11-month-old cat with a persistent right fourth aortic arch. A focal dilatation and ventral displacement of the esophagus is present between the thoracic inlet and heart. The contrast column tapers off and narrows at the heart base (black arrow) because of the vascular ring constriction.
Lateral thoracic radiograph of a 2-month-old German shepherd with a persistent right fourth aortic arch. The thoracic trachea is displaced ventrally, and there is a superimposed mottled mineral opacity because of foreign material in the enlarged esophageal segment cranial to the heart base. The caudal thoracic esophagus appeared normal. B, Ven- trodorsal (VD) radiograph of the same dog. The trachea is displaced to the left (white arrows).
Lateral (A) and dorsoventral (DV) (B) radiographs of a dog with a persistent right fourth aortic arch. There is dilatation of the cranial aspect of the thoracic esophagus that causes ventral displacement of the trachea. In the DV view, there is a mass effect in the cranial mediastinum. The caudal aspect of the thorax is normal.
stricture
stricture
How does the PRAA esophagus affect the trachea?
The dilated esophagus will usually displace the trachea ventrally, but can occasionally slide laterally and go ventral to the trachea. In some dogs, the trachea may be deviated to the left.
Where is the site of compression for an aRSA compared to a PRAA?
aRSA is slightly more cranial
Why should fluoro be performed in PRAA patients?
because esophageal dysfunction caudal to the compression is often present and this may limit the degree of resolution even if the vascular ring is surgically corrected
Which other anomaly can accompany a PRAA?
A persistent left cranial vena cava
This is important to recognise if a left-thoracotomy is performed.
From where does the right subclavian artery normal branch?
brachiocephalic trunk
From where does an aberrant right subclavian artery arise?
aortic arch, distal to the origin of the L subclavian artery
Which compression is (or can be) more severe - aRSA or PRAA?
PRAA; in aRSA the esophagus is not trapped against the trachea, like with PRAA.
Radiographic findings of severe esophagitis
- segmental narrowing
- irregular mucosal contours
- mural thickening
What causes esophageal strictures?
foreign bodies
gastroesophageal reflux
What can hint at esophageal strictures due to reflux under GA?
location: they are usually located in the caudal esophagus, caudal to the base of the heart
Which esophageal neoplasms are associated with a parasite?
Osteosarcoma and fibrosarcoma are reported in areas endemic for Spirocerca lupi.
(tropical and subtropical; Southern Africa up to India, Turkey, Greece, also southern USA)
What can dystrophic mineralisation of esophageal masses indicate?
Neoplasia, spirocerca lupi infection, ingestion of radiopaque meds
If there is no visible complete obstruction from an esophageal mass, why would barium be retained?
There may be a functional problem - lack of a secondary peristaltic wave where the wall is thickened due to neoplastic infiltration
Which esophageal parasite can cause granulomas that can undergo neoplastic transformation?
Spirocerca lupi - osteosarcoma, fibrosarcoma
- can also cause spinal cord chondrosarcoma
Spirocerca lupi mainly infests which two anatomical locations?
esophagus and aorta
2 secondary signs of spirocerca lupi (other than esophageal granuloma)?
- new bone formation at the ventral aspect of the thoracic vertebrae, dorsal to the mass (spondylitis)
- enlargement (aneurysm) of the descending aorta
Which (rare) abnormalities of the aorta can be caused by S. lupi?
- enlargement (aneurysm) of the proximal descending aorta
- mineralisation
How can you differentiate S.lupi granulomas from sarcomas?
CT angiography perfusion analysis
- granulomas are more perfused than sarcomas
What is an esophageal diverticulum?
Thinning of the wall, resulting in a bulge
What are the types of esophageal diverticula?
Pulsion
Traction
What causes a pulsion esophageal diverticulum?
increased intraluminal pressure: FB, chronic functional obstruction
Where are pulsion esophageal diverticula located typically?
between the heart and the diaphragm
What causes traction diverticula?
adhesions on the esophageal wall
Where are traction diverticula typically located?
cranial and mid-thoracic esophagus
What does an esophageal diverticulum look like?
Outpouching or soft tissue mass of the esophagus, with impacted ingesta or a mix of gas/ST content
With an esophageal rupture, what areas/spaces communicate with the perforation?
mediastinum and/or pleural space
What are 3 risk factors for complications of an esophageal perforation?
boney FB, <10kg bodyweight, >3d history
What is the complication rate of esophageal foreign bodies?
12.7%
Which has a better prognosis - cervical or thoracic perforations of the esophagus?
Cervical;
Thoracic may develop septic mediastinitis, pleuritis and pyothorax
Complications of esophageal foreign bodies
perforation, stricture, diverticula, periesophageal abscess, pneumothorax, pleural effusion, respiratory arrest
Which type of contrast might you consider to confirm an esophageal perforation? What are the downsides?
water-soluble contrast may not adhere to devitalised tissue or foreign object, or even bypass an obstruction and give a false negative diagnosis
What is the most common congenital esophageal fistula?
bronchoesophageal, but tracheoesophageal also occur
How (and where) do acquired esophageal fistulas happen?
Following an esophageal perforation, resulting in communication with a bronchus or the trachea
How do you diagnose an esophageal fistula?
Barium study or bronchoscopy
Cause of esophageal and paraesophageal varices?
portal hypertension
obstruction of the cranial vena cava
How does portal hypertension cause esophageal varices ?
causes the blood flow in the L gastric vein to course cranially to the venous plexus of the esophagus
differential (has similar appearance on CT angiography) for esophageal varices?
bronchoesophageal artery hypertrophy
What causes bronchoesophageal artery hypertrophy?
chronic pulmonary or thromboembolic disease
