Chapter 90 Oesophagus Flashcards
At what level does oesophagus regain dorsal position (to trachea)
At tracheal bifurcation
What are the layers of the oesophagus
- Adventitis
- Muscularis
- Submucosa
- Mucosa
N.B. No serosa
What proportion of oesophagus can be resected?
20% of cervical oesophagus
50% of thoracic oesophagus
But in practice excision of >3-5cm –> increased risk of dehisence
What is the distribution of skeletal/smoth muscel in canine oesophagus?
And feline?
In dogs 100% striated
In cats cranial 2/3rds striated, caudal 1/3 smooth muscle (–> herringbone appearance with contrast as caudal 1/3rd has transverse folds, rather than longitudinal)
How is the oesophagus anchored cranially?
Via cricooesophageal tendon to cricoid cartilage
What muscles form the upper oesophageal sphinter?
Thyropharyngeus and cricopharyngeus
What is the main arterial supply to:
- Cervical oesophagus
- Cranial thoracic
- Caudal thoracic
- Terminal oesophagus
- Cervical oesophagus = Cranial and caudal thyroid arteries
- Cranial thoracic (2/3rds) = Bronchooesophageal artery
- Caudal thoracic (1/3rd) = Aorta or dorsal intercostals
- Terminal = Left gastric artery
Which veins drain the oesophagus?
External jugular, azygous and left gastric
Which nerves innervate the oesophagus
Vagus:
- Pharyngo-oesophageal nerves
- Recurrent laryngeal and para-recurrent laryngeal nerves
- Dorsal and ventral vagal branches nerves
Label the diagram
Label the diagram
Left lateral view of the canine thoracic cavity; the lung and much of the pericardium have been removed.
1, Longus colli;
2, left subclavian artery;
3, internal thoracic vessels;
4, thymus;
5, vessels in paraconal interventricular groove;
6, pulmonary trunk;
7, esophagus;
8, pulmonary veins entering left atrium;
9, left principal bronchus and dorsal and ventral vagal trunks;
10, aorta;
11, sympathetic trunk;
12, phrenic nerve;
13, caudal mediastinum;
14, diaphragm.
Label the diagram
Right lateral view of the canine thoracic cavity; the lung and much of the pericardium have been removed.
1, Diaphragm;
2, infracardiac bursa;
3, sympathetic trunk;
4, esophagus;
5, caudal vena cava;
6, plica venae cavae;
7, root of lung and phrenic nerve;
8, right vagus;
9, right azygos vein;
10, cranial vena cava;
11, longus colli;
12, trachea;
13, thymus;
14, internal thoracic vessels;
15, first rib;
16, vagosympathetic trunk.
Name the three phases of swallowing:
-
Oropharyngeal
- Oral
- Pharyngeal
- Cricopharyngeal/pharyngo-oesophageal
-
Oesophageal (if dysfunction, then broken down as follows)
- Mechanical
- Functional
- Inflammatory
- Gastrooesophageal
What nerves co-ordinate swallowing>
V Trigeminal
VII Facial
IX Glossopharyngeal
X Vagus
XII Hypoglossal
On swallow study, a bolus of food stops in front of gastrooesophageal juntion and then enters stomach at next bolus - comment on this
Can be normal
How do oesophageal transit times vary with sternal vs lateral positioning?
Slower in lateral!
(7-9 cm/s in lateral vs 3-4 cm/s in sternal)
N.B. Book misquotes these numbers implying faster in lateral!
List 6 ddx for mechanical oesophageal dysfunction
- VRA
- Mural mass lesion
- Neoplasia
- Duplication cyst
- Paraoesophageal abcess
- Oesophageal diverticula
- Stricture
- FB
- Hiatal hernia
- Gastroesophageal intussusception
What is most common cause for canine megaoesophagus?
Idiopathic
List 5 factors that contribute to higher dehisence rate in oesophagus vs SI
- Lack of serosa
- Lack of omentum
- Segmental blood supply
- Constant movement with peristalisis and respiration
- Less mobile i.e. more tension
In what layer of the oesopagus does the rich intramural plexus of anastomosing vesels sit?
Submucosa
What is the significance of the rich intramural plexus of anastomosing vesels of the oesophagus?
Thoracic oesophageal anastomoses can heal after ligation of thoracic segmental blood supply (however simultaneous ligation of thoracic AND cervical supply –> necrosis).
i.e. ischaemic necrosis usually due to damage to the intramural supply
What are post-op feeding recommendations after oesophageal surgery?
Withhold for 1-7d.
Consider G- or E-tube
What approaches can be performed for cranial thoracic oesophagus
L 3rd or 4th ICT
R 3rd, 4th or 5th ICT
Cranial MS
When performing L ICT for access to cranial oesophagus, what other step is necessary?
And on R?
Left: Ventral retraction of brachiocephalic trunk and subclavian vessels
Right: Ventral retraction of trachea +- retraction/ligation of azygous vein
What is preferred approach for caudal thoracic oseophagus
L 7th, 8th, 9th ICT
(Alternatives = transdiaphragmatic or caudal MS)
Label the diagram
Approach to the cervical esophagus.
A, Position the patient in dorsal recumbency with the neck resting on a rolled towel.
B, The skin is incised from the larynx to the manubrium, and the sternohyoid muscles are separated to expose the trachea.
C, The trachea is retracted to the right to expose the esophagus, thyroid, carotid sheath, and recurrent laryngeal nerve.
Why is simple continuous closure of oesophagus not recommended (2 points)
- Had lowest wound strenght and poorest tissue apposition in study comparing it to simple interrupted + double layer patterns.
- Doesnt permit oesophageal dilation.
Name a technique to reduce anastomotic tension following oesophageal R+A
How is this facilitated?
Partial myotomy (N.B. leaving inner muscle intact! This prevents disruption of submucosal vascular plexus. Full thickness myotomy –> necrosis)
Inject saline between muscle layers to differentiate them
What was outcome of oesophageal R+A using biofragmentable anastomosis ring
4/30 mortality
Can also staple with EEA stapler (2/18 stapled –> stricture)
List local muscle flap options for oesophageal patching in:
Cervical oesophagus
Cranial thoracic
Caudal oesophagus
List alternative materials that can be used for in-lay patches or support patching
Cervical oesophagus:
- Sternohyoid pedicle graft
- Longus colli pedicle graft
Cranial thoracic
- Internal or external intercostal vascularised pedicle
Caudal oesophagus
- Internal or external intercostal vascularised pedicle
- Diaphragmatic vascularised pedicle graft
- Stomach
And can use the following:
- Omentum
- Pericardium
- Pedicled segment of gastric wall or jejunum
- Free buccal mucosal graft
- Porcine SIS
- Lyophilized duramater
- Collagen coated vicryl mesh
- ePTFE patches
List 7 options for oesophageal substitution
- Inversed tube skin graft (staged) or based on omocervical axial pattern flap (for single stage procedure)
- Tubed intercostal musculopleural pedicle patch
- Diaphragmatic pedicle graft
- Tubed lat dorsi musculocutaneous flap
- Gastric advancement oesophagogastric anastomosis
- Gastric tubes (peristaltic and anti-peristaltic - based on gastroepiploic vessles)
- Free microvascular grafts (intestine/colon)
When performing a gastric tube procedure for oesophageal substitution, what two additonal surgical procedures shoudl be performed and why?
- Splenectomy - becuase pedicle flaps are based on gastroepiploic vessels
- Pyloromyoplastyc - to facilitate astric emptying as vagal supply to stomach likely to be disrupted
What is most common VRA?
Which is most common causing clinical signs?
Most common = aberrant R subclavian but usually asymptomatic (present in 6% of dogs)
Most common clinically significant = PRAA + L ligamentum arteriosum
How many primordial aortic arches are there?
Which involute?
6 embryonic arches
Arches 1, 2 and 5 involute
A, The six primordial embryonic arches, the dorsal and ventral aortas, and their normal development in postnatal structures. Only arches three, four, and six are retained in their original forms as adult structures.
B, Normal embryology of the aortic arches and postnatal arrangement of the vessels in dogs and cats.
Embryonic arches 1,2 and 5 involute. What is the fate of each of the other arches?
RIGHT SIDE:
- 3rd arch: Common carotid
- 4th arch: Brachiocephalic trunk + R subclavian
- 6th arch: Pulmonary artery
LEFT SIDE:
- 3rd arch: Common carotid
- 4th arch: Aortic arch
- 6th arch: Pulmonary artery + ductus arteriosus (ligamentum arteriosum)
N.B.
- L subclavian develops from L 7th intersegmental artery
- Internal carotid comes from dorsal aortas
- External carotid comes from ventral aortas
Which embryonic arch form common carotids?
3rd aortic arch
Which aortic arch forms the r subclavian and brachiocephalic trunk?
R 4th aortic arch
Which embryonic aortic arch forms aortic arch?
L 4th aortic arch
Which embryonic aortic arch is retained in PRAA?
R 4th aortic arch (instead of L 4th aortic arch)
Which embryological aortic arches form plumonary arteries
6th aortic arches
What embryonic structure forms L subclavian artery?
L 7th intersegmental artery
Which embryonic aortic arch forms the ductus arteriosus/ligamentum arteriosum?
L 6th aortic arch
Which embryonic structures form the external carotids?
And internal carotids?
External carotids: Ventral aortas
Internal carotids: Dorsal aortas
Name the VRAs
A, The six primordial embryonic arches, the dorsal and ventral aortas, and their normal development in postnatal structures. Only arches three, four, and six are retained in their original forms as adult structures.
B, Normal embryology of the aortic arches and postnatal arrangement of the vessels in dogs and cats.
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. This type of anomaly may also result in respiratory signs secondary to constriction of the trachea along with the esophagus.
E, Persistent right ductus arteriosus (RDA), essentially the mirror image of persistent RAA. The aortic arch develops normally on the left, but the right sixth arch persists as the ductus arteriosus. The RDA arises from the pulmonary artery and extends to the aortic arch, compressing the esophagus on its right side.
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.
(A, Aorta; AA, aortic arches; BCT, brachiocephalic trunk; CC, common carotid; CI, cervical intersegmental arteries; DA, dorsal aorta; EC, external carotid; IC, internal carotid; LAA, left aortic arch; LPA, left pulmonary artery; LS, left subclavian; MPA, main pulmonary artery; RPA, right pulmonary artery; RS, right subclavian; VA, ventral aorta.)
What condition is shown in oesophagoscopy image?
Bilateral oesophageal diverticula (could say fistula i suppose if based on just image)
DDx for this?
- Oesophageal diverticulum
- GEI
- Hiatal hernia
Label the image
Normal lateral fluoroscopic view of the pharynx at rest. Note that radiodensity is reversed in fluoroscopic images compared with conventional radiographs (i.e., air is white and bone is black).
1, Nasopharynx;
2, soft palate;
3, base of tongue;
4, epiglottis;
5, trachea;
6, cranial esophageal sphincter;
7, cranial esophagus with barium in the lumen.
describe lateral approach for cricopharyngeal myotomy
- An orogastric tube placed
- A skin incision is made dorsal to the larynx and ventral to the jugular vein, starting at the cranial aspect of the jugular vein.
- The subcutis and platysma are transected, and Gelpi retractors are inserted so that the sternocephalicus muscle and jugular vein are retracted dorsally and the sternohyoideus muscle ventrally.
- The thyroid cartilage is identified and loose connective tissue dissected free to expose, from cranial to caudal, the thyropharyngeus and cricopharyngeus muscles and esophagus.
- The cricopharyngeus muscle is dissected free from the esophagus laterally and dorsally, and a 2.0- to 2.5-cm section is removed from the dorsal midline, being careful to ensure that all the muscle fibers are cut without penetrating the esophageal wall.
- Place vasculr clips at edges of myotomy to facilitate identification on follow up fluoro
- The resected tissue is submitted for histologic evaluation, and the subcutaneous tissues and skin are reapposed routinely.
Comment of fluoro study
Lateral fluoroscopic view of barium swallow. Barium appears black on fluoroscopy.
Row 1, Normal dog;
- 1A, liquid barium bolus in the pharynx;
- 1B, closure of the epiglottis at the onset of swallowing;
- 1C, opening of the cranial esophageal sphincter;
- 1D, closure of the cranial esophageal sphincter and reopening of the epiglottis.
Row 2, Dog with cricopharyngeal achalasia;
- 2A, liquid barium bolus in the pharynx;
- 2B, contraction of pharynx without opening of the cranial esophageal sphincter;
- 2C, opening of cranial esophageal sphincter and reopening of the epiglottis
- 2D, closure of the cranial esophageal sphincter.
Look at this table of ddx for dysphagia
Look at this table of ddx for dysphagia
