Kapitel 90 - Esophagus

Question 1

Name the layers of esophagus, from the outermost to the inner

Answer 1

• Adventitia (outermost)
• Muscularis (straited muscles all the way in dogs, smooth muscle in the terminal esophagus in cats)
• Submucosa
• Mucosa

Question 2

What structures make up the cranial (upper) esophageal sphincter?

Answer 2

Thyropharyngeous and cricopharyngeous muscles and associated elastic tissue

Question 3

What are the main arterial supply to the esophagus?

Answer 3

Cervical portion: Branches from the cranial and caudal thyroid arteries.

Cranial 2/3 of the thoracic portion: bronchoesophageal artery

Caudal 1/3 of thoracic portion: esophageal branches of the aorta or dorsal intercostal arteries

Terminal portion: Branch of the left gastric artery

Question 4

Describe the phases of normal swallowing.

Answer 4

a. Oropharyngeal, Subdivided into 3 stages:
- Oral – voluntary step –> Prehension, mastication and food bolus delivered to the base of the tongue
- Pharyngeal - first step of the involuntary phase of swallowing. Pharyngeal constrictor muscles moves food bolus into the cricopharynx. Contraction of the palatal and pharyngeal muscles closes the nasopharynx and prevents nasal reflux, and caudal epiglottic reflection and vocal fold adduction close the larynx and prevent laryngotracheal aspiration.
- cricopharyngeal - relaxation of thyropharyngeus and cricopharyngeus muscles and delivery of the bolus into the cranial cervical esophagus

b. Esophageal - Coordinated contraction of esophageal musculature in peristaltic waves. Bolus delivered to the gastroesophageal sphincter

c. Gastroesophageal - Gastroesophageal sphincter relaxes –> Bolus passes into the stomach

Question 5

What nerves coordinate the oropharyngeal phase of swallowing?

Answer 5

a. trigeminal (V)
b. facial (VII)
c. glossopharyngeal (IX)
d. vagus (X)
e. hypoglossal (XII)

Question 6

Name the broad division of the causes of dysfunction during the esophageal phase of swallowing

Answer 6

a. mechanical (or anatomic) lesions – foreign bodies, strictures, tumours, vascular ring abnormalities, hiatal hernia etc.

b. functional (or neuromuscular) lesions – neuromuscular disease, commonly causing megaesophagus.

c. inflammatory (esophagitis) – gastroesophageal reflux, persistent vomiting, ingestions of chemical/corrosive substanses, thermal injury etc.

Question 7

What factors contribute to the high complication rate of esophageal surgery?

Answer 7

a. lack of serosa
b. the segmental nature of the blood supply (with a rich, intramural plexus of anastomosing vessels in the submucosal layer that can support long segments of the esophagus –> can cause ischemic necrosis at the incision site)
c. the lack of omentum
d. constant motion caused by swallowing and respiration
e. tension at the surgical site

Question 8

List the surgical approaches to the esophagus

Answer 8

Cervial part:
- Ventral midline incision

b. Cranial thoracic part:
- 3rd-4th IC thoracotomy on left side. Then ventral retraction of the brachiocephalic trunc and subclavian vessels.
- 3rd, 4th or 5th IC thoracotomy on the right side. Then ventral retraction of the trachea and retraction or ligation of the azygos vein.

c. Caudal thoracic part:
- 7th, 8th or 9th IC thoracotomy on left side

d. Caudal part:
- combined ventral midline laparotomy and diaphragmatic incision or caudal median sternotomy.

Question 9

What suture materials are recommended for suturing esophagus? And how should the sutures be placed?

Answer 9

a. Monofilament, minimally reactive, slowly absorbable suture materials, such as polydioxanone (PDS) or polyglyconate (Maxone)

b. approximately 2 mm from the cut edge and 2 to 3 mm apart in an interrupted pattern (recommended, single or double layered)

Question 10

Describe the technique of suturing the esophagus in a single layer and in double layer

Answer 10

Single: Suture passes through all layers of the esophageal wall, with limited penetration of the mucosa, and knots are placed extraluminally.

Double: first layer incorporates mucosa and submucosa, and knots are placed in the esophageal lumen. The second layer apposes the muscularis and adventitia, with knots placed extraluminally.

Question 11

For how long should food and water by month be withdrawn after esophageal surgery?

Answer 11

a. At least 24-48 h (24 h – 7 days depending on author)

b. At least 7 days if resection and anastomosis

Question 12

How much of the esophagus can you resect?

Answer 12

3-5 cm (more than that increases the risk of dehiscence)

Question 13

Give examples esophageal patches and how would you apply them.

Answer 13

Can be autogenic:
- omentum, pericardium, local muscle flaps, stomach or intestine

Or xenogenic (artificial): - porcine small intestinal submucosa, lyophilized dura mater, collagen-coated Vicryl mesh, and expanded polytetrafluoroethylene patches

a. Applied as an “on-lay” patch in cases of esophagotomy or anastomosis

b. Applies as an “in-lay” patch in cases of longitudinal division of an esophageal stricture.

Question 14

Describe how you create an omental pedicle flap

Answer 14

a. Paracostal or midline abdominal incision. The right gastroepiploic artery and its branches to the omentum are ligated. The flap is brought through a small incision in the diaphragm, taking care to preserve the blood supply. The omentum is then tacked at multiple sites around the esophageal wound with absorbable suture.

Question 15

What patch would be suitable for cervical esophagus?

Answer 15

A pedical muscle flap of sternothyroideus and longus colli muscles

Question 16

What patch would be suitable for the caudal thoracic esophagus? Give example of other reconstructive techniques of this part of the esophagus.

Answer 16

a. Diaphragmatic pedicle graft

other techniques:
b. Gastric advancement and esophagogastric anastomosis.
c. Isoperistaltic and antiperistaltic gastric tubes.

Question 17

What skin graft can be used as an inversed tubed skin graft? List the potential complication of this technique

Answer 17

a. An omocervical cutaneous island axial pattern flap for the cervical esophagus.

Complications:
- luminal obstruction with hair
- lack of peristalsis
- indistensibility of the graft.

Question 18

What are potential complications gastric advancement and esophagogastric anastomosis.

Answer 18

a. Leakage
b. Stricture
c. Chronic vomiting
d. Reflux esophagitis
e. Gastric dilatation within the thoracic cavity
f. Herniation of other abdominal viscera through an inadequately reconstructed diaphragm

Question 19

A. What is the difference between isoperistaltic and antiperistaltis gastric tubes?

B. What additional procedure are required for the procedures?

C. What’s the feeding guidelines after these techniques?

Answer 19

a. An antiperistaltic, or reverse, gastric tube is created from the greater curvature of the stomach, maintaining the luminal connection at the fundus. The tube is advanced into the thoracic cavity and anastomosed to the cut end of the esophagus.
An isoperistaltic gastric tube is created in a similar fashion, but the tube is separated at both ends to create a pedicle graft. The isoperistaltic tube technique maintains gastric tube peristalsis in an aboral direction but requires two anastomoses

b. Splenectomy, ligation of the omental branches of the gastroepiploic vessels and pylorymyoplasty (to enhance gastric emptying because disruption of vagal innervation is likely)

c. Animals are fed by jejunostomy tubes for at least 1 week after surgery.

Question 20

Name the different vascular rings

Answer 20

A. The six primordial embryonic arches
B. Normal embryology of the aortic arches and postnatal arrangement of the vessels
C. Persistent right aortic arch (RAA). The right fourth arch, instead of the left, becomes the functional aorta. The ligamentum arteriosum (LA) extends between the left pulmonary artery and the anomalous RAA, causing constriction of the esophagus by the vascular ring.
D. Double aortic arch (DAA): both the left and the right fourth arches persist and are functional.
E. Persistent right ductus arteriosus (RDA), essentially the mirror image of persistent RAA.
F. Aberrant left subclavian artery: an example of a partial vascular ring anomaly. The left subclavian arises from the persistent RAA and compresses the esophagus on its dorsal aspect as the artery traverses from right to left in the cranial mediastinum.
G. Aberrant left subclavian artery with persistent RAA. Similar to F except a left LA connects the pulmonary artery to the persistent RAA. The esophagus is dually compressed by a complete vascular ring (persistent RAA with left LA) and by a partial vascular ring (aberrant left subclavian).
H. Aberrant right subclavian artery: the right subclavian artery arises from the normal left aortic arch rather that the brachiocephalic trunk, thus compressing the esophagus on its dorsal aspect as the artery traverses to the right side.

Question 21

Which one is the most common vascular ring anomality?

Answer 21

persistent right aortic arch with a left ligamentum arteriosum (95% of vascular anomality in dogs)

Question 22

What dog and cat breeds are predisposed to vascular ring anomality?

Answer 22

a. Dogs: German Shepard and Irish Setter
b. Cats: Persians and Siamese

Question 23

On a ventrodorsal radiograph you see a marked, focal leftward curvature of the trachea combined with a focal tracheal narrowing. What is your diagnosis?

Answer 23

Persistent right aortic arch

Question 24

What is the surgical approach for correction of vascular ring anomalies?

Answer 24

a. Most can be corrected through a left lateral thoracotomy.

b. Persistent right ligamentum arteriosum with a left aortic arch should be approached through a right lateral thoracotomy

Question 25

Where is esophageal foreign bodies most commonly located? What is the most common clinical sign?

Answer 25

a. The thoracic inlet, the heart base and caudal esophagus. b. Regurgitation of food within a few min of eating.

Question 26

Describe the surgical approach and correction of Persistent right aortic arch with a left ligamentum arteriosum

Answer 26

o Left 4th intercostal thoracotomy in dogs; in cats a left 5th intercostal thoracotomy. o The cranial lung lobe is packed off caudally with moistened sponges. o The dilated cranial thoracic esophagus is visible over the base of the heart. o A left persistent cranial vena cava, if present, can be retracted dorsally and does not need to be ligated. o If a prominent hemiazygos vein is also present, it should be ligated and divided as it courses close to the vascular ring. o The mediastinum is incised longitudinally over the vascular ring, carefully preserving the vagus nerve and its branch, the left recurrent laryngeal nerve, o The pulmonary artery, aorta, and connecting ligamentum arteriosum are identified o The ligamentum arteriosum is carefully dissected from the esophagus with right-angled forceps, double ligated with silk suture, and transected. o A stiff tube or balloon catheter is then inserted through the mouth into the esophagus, and any remaining constricting fibrous bands are identified and transected.

Question 27

What factors may negatively affect the prognosis of vascular ring anomality’s?

Answer 27

a. degree of esophageal constriction and dilatation b. severity of esophageal impairment c. presence and severity of aspiration pneumonia before correction d. medical management before and after surgery

Question 28

How should esophageal perforation be treated?

Answer 28

a. Evaluation of the size of perforation and the health of the adjacent esophageal tissue – small perforations may seal on their own and oral intake of food and water is prohibited for 72 h b. Cervical perforations may only require local drainage c. Surgical repair should be considered if contrast material migrates away from the focal area of perforation or if pleural effusion, pneumothorax, pneumomediastinum, or sepsis is present. i. Patients should be observed carefully for 2 to 3 days for signs of esophageal leakage.

Question 29

What is the most common cause of esophageal stricture?

Answer 29

Esophageal reflux during anesthesia. - Generally presents within 3 weeks of anesthesia. - Can occure at any level of the esoophagus

Question 30

What is the preferred treatment of esophageal strictures? What are the surgical options?

Answer 30

a. Bougienage or balloon dilatation is the preferred treatment b. Surgical resection for strictures that fail to respond to dilatation or bougienage or for animals in which the esophagus perforates during dilatation. Surgical options: - simple esophagoplasty, esophageal resection and anastomosis, patch esophagoplasty, and esophageal substitution

Question 31

How do you treat an esophageal fistula?

Answer 31

a. Total intravenous anesthesia (along with oxygen supplementation via mechanical ventilation) or bronchial intubation may be necessary until the fistula has been sealed. b. A lateral thoracotomy is performed c. The fistulous tract should be excised rather than ligated and closed primarily (although more extensive resection and reconstruction techniques may be required. d. If fistula is communicating with a lung, lung lobectomy is necessary.

Question 32

Where is the most common location of bronchoesophagealfistual in dogs?

Answer 32

Bronchoesophageal fistulas most frequently communicate with the right caudal lung lobe bronchus

Question 33

Why is it important to differentiate cricopharyngeal dysphagia from pharyngeal dysphagia?

Answer 33

cricopharyngeal dysphagia improves with cricopharyngeal myotomy while pharyngeal dysphagia worsens.

Question 34

List the most common malignant and benign neoplasia in dogs and where are neoplasia most commonly located in dogs?

Answer 34

Malignant: squamous cell carcinoma, leiomyosarcomas, osteosarcoma, fibrosarcoma, and undifferentiated sarcoma Benign: leiomyoma and plasmacytoma Location: caudal thoracic esophagus

Question 35

What’s the most common esophageal neoplasia in cat and the most common location?

Answer 35

a. Squamos cell carcinomas. b. Cranial thoracic esophagus