Upper GI Tract Flashcards
How does the upper oesophageal sphincter open vs the lower oesophageal sphincter?
UOS = reflexively
LOS = by vasovagal reflex (receptive relaxation reflex)
What are the anatomical contributors from the upper GI tract to the lower oesophageal sphincter?
Is the 3-4 cm distal oesophagus within abdomen
• diaphragm surrounds LOS (Lt & Rt crux)
• intact phrenoesophageal ligament
• angle of His
Intraabdominal pressure
what type of muscle makes up the lower thoracic oesophagus/ oesophageal junction?
Smooth muscle
At what vertebral level is the angle of His found?
T10
What are the four stages of swallowing?
Stage 0: oral phase
Stage 1: pharyngeal phase
Stage 2: upper oesophageal phase
Stage 3: lower oesophageal phase
What happens during stage 0 of swallowing?
How is the motility of the oesophagus determined?
determined by pressure measurements (manometry)
• peristaltic waves ~ 40 mmHg
• LOS resting pressure ~ 20 mmHg
> ↓<5 mmHg during receptive relaxation
How is motility of the oesophagus mediated?
mediated by inhibitory noncholinergic nonadrenergic (NCNA) neurones of myenteric plexus
What are the common functional disorders of the oesophagus?
Absence of a stricture
• Abnormal oesophageal contraction
> Hypermotility
> Hypomotility
> Disordered coordination
• Failure of protective mechanisms for reflux
> Gastro-oesophageal reflux disease (GORD)
What is dysphagia? Why are the 2 descriptive terms for localisation?
Difficulty swallowing
Localisation is important - cricopharyngeal sphincter or distal
What is odynophagia?
Pain on swallowing
Define regurgitation
Regurgitation = return of oesophageal contents from above an obstruction
> may be function or mechanical
Define reflux
Reflux = passive return of gastroduodenal contents to the mouth
What causes achalasia?
Loss of ganglion cells in Aurebachs myenteric plexus in LOS wall causing decreased activity of inhibitory NCNA neurones
What is the aetiology behind primary achalasia?
Unknown
What is the aetiology behind secondary achalasia?
Diseases causing oesophageal motor abnormalities similiar to primary achalasia
What effect does achalasia have on the resting pressure of the LOS?
Increased
What are 3 examples of secondary achalasia?
Chagas’ disease
Protozoa infection
Amyloid/sarcoma/eosinophilic oesophagitis
outline the 8 steps of the proposed model of achalasia pathophysiology
Proposed model of achalasia pathophysiology
1. environmental trigger - chronic infections
2. genetic predisposition
3. first stagenon-autoimmune inflammatory infiltrates
4. promotes would repair and fibrosis
5.loss of immunological toleranceleads to autoimmune inflammatory infiltrates
6. apoptosis of neurones
7. humoral response - autoimmune
8. all leads to myenteric neurone abnormalities
What are the symptoms of achalasia?
Retrosternal pain, weight loss, dilated oesophagus, aperistalsis, bird beak in barium swallow, increased LOS pressure
what is aperistalsis?
Absence of peristalsis- radially symmetrical contraction and relaxation of muscles
What are the two most common complications of achalasia?
Oesophagitis, aspiration pneumonia
Give an example of oesophageal hypermotility
Achalasia
Give an example of oesophageal hypomotility
Scleroderma
Where does iatrogenic oesophageal perforation usually occur
At OGD, located above cricopharyngeal muscle
A normal barium swallow rules out achalasia. True or false
False, it is a late feature
What are the different types of dysphagia?
For fluids or solids, Intermittent or progressive, precise or vague in appreciation
Describe the progression of achalasia
> hasinsidious onset- symptoms for years prior to seeking help
without treatment → progressive oesophageal dilatation of oesophagus
• risk of oesophageal cancer increased28-fold
What are the three methods of treatment for achalasia?
Pneumatic dilatation
Hellers myotomy and Dor fundoplication
What occurs during pneumatic dilatation to treat achalasia?
PD weakens LOS by circumferential stretching, and in some cases tearing of muscle fibres. This helps to restore flow
What is the efficacy of pneumatic dilatation to treat achalasia?
71-90% of patients respond initially but many relapse
What treatment is given to treat achalasia after relapse following pneumatic dilatation?
Hellers myotomy and Dor fundoplication
What is Hellers myotomy?
Continuous myotomy performed for 6cm on opesophagus and 3cm onto cardia of the stomach
What is Dor fundoplication?
Anterior fundus folded over oesophagus and sutured to right side of myotomy
What are the risks associated with a Hellers myotomy and Dor fundoplication?
Oesophageal and gastric perforation, division of vagus nerve, splenic injury
What occurs during a peroral endoscopic myotomy to treat achalasia? (POEM)
Mucosal incision, creation of submucosal tunnel, myotomy, closure of mucosal incision
What is scleroderma?
An autoimmune disease causing early hypomotility due to neuronal defects. This causes atrophy of smooth muscle of oesophagus
What happens to peristalsis in the distal oesophagus during scleroderma?
Ceases all together
Scleroderma treatment?
Exclude organic obstruction.
Improve force of peristalsis with pro kinetics such as cisapride
Once peristaltic failure occurs is usually irreversible
What is an example of a disordered oesophageal coordination?
Corkscrew oesophagus
What is corkscrew oesophagus?
Incoordinate contractions cause dysphagia and chest pain
What is seen in the circular muscle of the oesophagus in corkscrew oesophagus?
Marked hypertrophy
Corkscrew oesophagus treatment?
May respond to forceful pneumatic dilatation, however results not as predictable as achalasia
What vascular anomalies cause dysphagia?
Dysphagia Lusoria cause by aberrant right subclavian artery
Double aortic arch
How does an aberrant right subclavian artery cause dysphagia lusoria?
Constricts the oesphagus against the trachea meaning the right subclavian needs to be reconnect at the right position
What oesophageal constrictions cause dysphagia?
Cricopharyngeal constriction
Aortic and bronchial constrictions
Diaphragmatic and sphincter constriction
What are the common causes of oesophageal perforations?
Iatrogenic (OGD), spontaneous (Boerhaaves), foreign body, trauma, intraoperative, malignant
An iatrogenic oesophageal perforation is more common at GOD in the presence of what?
Diverticula or cancer
What is Boerhaaves ?
A spontaneous oesophageal perforation caused by sudden increase in intra-oesophageal pressure with negative intrathoracic pressure - for example vomitting against a closed epiglottis
What foreign body’s often cause oesophageal perforations?
Disk batteries, magnets, sharp objects, dishwasher tablets, acid/alkali
What inter-operative oesophageal perforations are most common?
Hiatus hernia repair, hellers cardiomyotomy, pulmonary surgery, thyroid surgery
What are some malignant causes of oesophageal perforations?
Advanced cancers, treated with radiotherapy, dilation, stenting, poor prognosis
What investigations can be done to investigate oesophageal perforations?
CXR, CT, swallow (gastrograffin), OGD
What is done to treat oesophageal perforation?
Initial management (NBM, IV fluids, broad spectrum ABs and anti fungal)
When investigating an oesophageal perforation what questions do we think of?
Is the perforation transmural and intramural?
Where is it and on which side?
How big?
Is the leak well defined or diffuse?
Failure of protective mechanisms against reflux in the stomach can lead to what?
GORD or a hiatus hernia
What protective mechanisms are there against reflux in the stomach?
LOS usually closed as barrier against reflux of harmful gastric juice
Swallowing
Pressure on full stomach
Transient sphincter opening
Following reflux in stomach what protective mechanisms are there? (3)
Volume clearance - oesophageal peristalsis reflex
pH clearance - saliva
Epithelium - barrier properties
How is oesophageal perforation managed?
Operative management - conservative management with covered metal stent
Primary repair is optimal - vascularised pedicle flap, gastric fundus buttressing
Oesophagectomy - definitive solution, reconstruction or oesophagostomy and delayed reconstruction
When is operative management for oesophageal perforation not conducted?
Minimal contamination or the patient is unfit
What mechanisms lead to GORD
• reduced sphincter pressure
• transient sphincter opening
• abnormal peristalsis - reduced volume clearance
• reduced saliva production (in sleep, xerostomia)
• buffering capacity of saliva (smoking)
> reduced pH clearance
• hiatus hernia
• defective mucosal protective mechanism (eg alcohol)
→ reflux oesophagitis
What are the different types of hiatus hernia?
• Sliding
> stomach moves up through the oesophageal hiatus
• Rolling/paraoesophageal
> stomach herniates to the side of the GOJ
> surgical emergency
What is a hiatus hernia?
Hiatus hernia is the protrusion of intra-abdominal contents into the thoracic cavity through an enlarged oesophageal hiatus of the diaphragm.
How is GORD investigated?
OGD to exclude cancer or confirm oesophagitis, peptic stricture, and Barrett’s oesophagus
Oesophageal manometry
24hr oesophageal pH recording
At what vertebral level does the oesophagus begin and end?
Begins at C5 and ends at T10
What happens during stage 0 of swallowing?
Chewing and saliva prepare bolus
Both oesophageal sphincters constricted
What occurs during stage 1 of swallowing? What is this stage called?
Pharyngeal phase
Pharyngeal musculature guides food bolus towards oesophagus
UOS opens reflexly
LOS opened by vasovagal reflex
What occurs during stage 2 of swallowing?
UOS closes
Superior circular muscle rings contract and inferior rings dilate
Sequential contractions of longitudinal muscle
What occurs during stage 3 of swallowing?
LOS closes as food passes through
Following a decrease in resting pressure in LOS in scleroderma, what disease often develops and what is often associated?
GORD develops, often associated with CREST syndrome
What are the functions of the stomach?
Breaks food into smaller particles (acid & pepsin)
• Holds food, releasing it in controlled steady rate into duodenum
• Kills parasites & certain bacteria
Where in the stomach is mucus secreted?
Cardia, pyloric region, body, fundus
Where in the stomach is HCl secreted?
Body and fundus
Where in the stomach is pepsinogen secreted?
Body and fundus
Where in the stomach is gastrin secreted?
Antrum
What are the four different types of gastritis?
Erosive and haemorrhagic
Nonerosive, chronic active
Atrophic
Reactive
What causes erosive and haemorrhagic gastritis?
Acute ulcer causing gastric bleeding and perforation
Where does nonerosive, chronic active gastritis affect in the stomach and what bacteria is the cause?
Antrum
Helicobacter pylori
Where does atro phic gastritis affect in the stomach and how, what affect does it have?
Affects the fundus (fundal gland)
Autoantibodies vs parts and products of parietal cells
Parietal cell atrophy
Decrease in acid and IF secretion - can lead to pernicious anaemia
What neural stimulation regulates gastric secretion?
ACh - postganglionic transmitter of Vagal parasympathetic fibres
What endocrine stimulation regulates gastric secretion?
Gastrin from G cells of antrum
What paracrine stimulation regulates gastric secretion?
Histamine from ECL cells and mast cells of gastric wall
What endocrine inhibition regulates gastric secretion?
Secretin from small intestine
What paracrine inhibition regulates gastric secretion?
Somatostatin
What paracrine and autocrine inhibition regulates gastric secretion?
Prostaglandins, TGF-alpha and adenosine
What four methods of mucosal protection are there in an ulcer?
Mucus film, HCO3- secretion, epithelial barrier, mucosal blood perfusion
What 3 mechanisms are there for repairing epithelial defects?
Migration, gap closed by cell growth, acute wound healing
How does migration repair epithelial defects in an ulcer?
Adjacent epithelial cells flatten to close gap via side wards migration along BM
How does gap closing by cell growth occur to repair epithelial defects due to an ulcer?
Stimulated by EGF, TGF-alpha, IGF-1, GRP and gastrin
How does acute wound healing occur to repair epithelial defects?
• BM destroyed - attraction of leukocytes & macrophages; phagocytosis of necrotic cells; angiogenesis; regeneration of ECM after repair of BM
• epithelial closure by restitution & cell division.
What are the four clinical outcomes of infection by H.pylori?
Asymptomatic or chronic gastritis
Chronic atrophic gastritis or intestinal metaplasia
Gastric or duodenal ulcer
Gastric cancer or MALT lymphoma
What are the first line treatment options for an ulcer?
PPI or H2 blocker
Triple Rx amoxicillin, clarithromyocin, pantoprazole
If unsuccessful elective surgical Rx
In the elective surgical Rx of ulcer treatment what is checked and what procedure is undergone?
Check serum gastrin for Antral G-cell hyperplasia or gastrinoma (Zollinger-Ellison syndrome)
OGD biopsy of all 4 quadrant of ulcer if refractory
What are the surgical indications associated with ulcer treatment??
• Intractability (after medical therapy) • Relative: continuous requirement of
steroid therapy/NSAIDs • Complications
• Haemorrhage • Obstruction
• Perforation
Is conservative management or operative management for an oesophageal perforation the default?
Operative management
What things can cause increased LOS pressure?
Acetylcholine
Alpha-adrenergic agonists
Protein-rich food
Histamine
High Intra-abdominal pressure
What things can cause a decrease in LOS pressure and what does this promote?
Promotes acid reflux
Vasoactive intestinal peptides (VIP)
Beta-adrenergic agonists
Dopamine
Acid gastric juice
Fatty foods
Chocolate
Ethanol
When does sporadic reflux occur?
When there is unexpected pressure on a full stomach
When swallowing
When there is transient sphincter opening
Following reflux, what three mechanisms act to protect us?
Volume clearance - esophageal peristalsis reflex
pH clearance - Saliva acts as a buffer as it enters the esophagus
Barrier properties of the distal epithelium
