Ischaemic Enteritis Flashcards
What causes infarction of the intestine
ACUTE occlusion of the coeliac, SMA or IMA
Why does gradual occlusion have little effect
Because of anastomotic circulation
What does occlusion of small end arteries result in
Small and focal lesions
What are the 2 causes of intestinal ischaemic injury
Occlusive - obstruction of mesenteric arteries
Non-occlusive - blood supply falls so far so that mucosal nutrition can’t be maintained
How is acute ischaemia classified
According to the depth of involvement:
- Mucosal
- Mural
- Transmural
What is mucosal ischaemia and what does it cause and lead to
Transient hypoperfusion:
Release of enzymes and increased permeability to toxic substances
CVS deterioation
Transmural infarction
What is mural ischaemia and what does it cause and lead to
Chronic hypo perfusion which reaches the submucosa
Mucosa becomes ulcerated and haemorrhagic
Necrosis causes healing by granulation tissues and fibrous strictures
What is transmural ischaemia and what does it cause and lead to
Major vessel occlusion extending through the muscularis propria
Bowel becomes flaccid and dilates
Serosa is congested
Perforation of wall
Predisposing occlusive conditions for ischaemia
Atherosclerosis Vasculitis Dissecting aneurysm OCP Embolism
Predisposing non-occlusive conditions for ischaemia
Cardiac failure
Shock
Dehydration
Vasoconstrictive drugs
What is vulnerable to acute ischaemia and why
the splenic flexure
the SMA and IMA branches overlap creating weak watershed areas which are vulnerable when blood flow decreases
Histology of acute ischaemia
Oedema
Gangrene and perforation
Vascular dilation
Characteristics of chronic ischaemia
Mucosal & submucosal inflammation
Ulceration
Fibrosis
Stricture
Where do strictures form most often
Large intestine in watershed areas around splenic flexure
