Ischemic colitis pathophysiology: Difference between revisions
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==Overview== | ==Overview== | ||
Ischemic colitis is the result of a sudden, temporary, reduction in [[blood]] flow that is insufficient to meet the [[Metabolism|metabolic]] demands of the region of [[Colon (anatomy)|colon]]. [[Ischemia|Ischemic]] change will subsequently extend from the [[Mucous membrane|mucosa]] to the [[Serous membrane|serosa]]. [[Mucous membrane|Mucosal]] injury will develop in 20 minutes to 1 hour, and transmural infarction occurs within 8 to 16 hours. [[Reperfusion injury]] can occur with the release of [[reactive oxygen species]], which cause [[lipid peroxidation]] within [[Cell membrane|cell membranes]], causing [[Cell (biology)|cell]] [[necrosis]]. | |||
==Pathophysiology== | ==Pathophysiology== | ||
The pathophysiology of ischemic colitis is as follows:<ref name="pmid9146713">{{cite journal| author=Rosenblum JD, Boyle CM, Schwartz LB| title=The mesenteric circulation. Anatomy and physiology. | journal=Surg Clin North Am | year= 1997 | volume= 77 | issue= 2 | pages= 289-306 | pmid=9146713 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=9146713 }} </ref><ref name="pmid6263743">{{cite journal| author=Granger DN, Rutili G, McCord JM| title=Superoxide radicals in feline intestinal ischemia. | journal=Gastroenterology | year= 1981 | volume= 81 | issue= 1 | pages= 22-9 | pmid=6263743 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=6263743 }} </ref><ref>Brandt LJ, Boley SJ, Goldberg L, et al: Colitis in the elderly. Am J Gastroenterol 76:239, 1981.</ref><ref name="WashingtonCarmichael2012">{{cite journal|last1=Washington|first1=Christopher|last2=Carmichael|first2=Joseph|title=Management of Ischemic Colitis|journal=Clinics in Colon and Rectal Surgery|volume=25|issue=04|year=2012|pages=228–235|issn=1531-0043|doi=10.1055/s-0032-1329534}}</ref> | The [[pathophysiology]] of ischemic colitis is as follows:<ref name="pmid9146713">{{cite journal| author=Rosenblum JD, Boyle CM, Schwartz LB| title=The mesenteric circulation. Anatomy and physiology. | journal=Surg Clin North Am | year= 1997 | volume= 77 | issue= 2 | pages= 289-306 | pmid=9146713 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=9146713 }} </ref><ref name="pmid6263743">{{cite journal| author=Granger DN, Rutili G, McCord JM| title=Superoxide radicals in feline intestinal ischemia. | journal=Gastroenterology | year= 1981 | volume= 81 | issue= 1 | pages= 22-9 | pmid=6263743 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=6263743 }} </ref><ref>Brandt LJ, Boley SJ, Goldberg L, et al: Colitis in the elderly. Am J Gastroenterol 76:239, 1981.</ref><ref name="WashingtonCarmichael2012">{{cite journal|last1=Washington|first1=Christopher|last2=Carmichael|first2=Joseph|title=Management of Ischemic Colitis|journal=Clinics in Colon and Rectal Surgery|volume=25|issue=04|year=2012|pages=228–235|issn=1531-0043|doi=10.1055/s-0032-1329534}}</ref> | ||
===Colonic Blood Supply=== | ===Colonic Blood Supply=== | ||
* Colon receives blood from | * [[Colon (anatomy)|Colon]] receives [[blood]] from the [[superior mesenteric artery|superior]] and [[inferior mesenteric artery|inferior mesenteric arteries]]. | ||
*Blood supply from these | *[[Blood]] supply from these [[Artery|arteries]] overlap, with abundant collateral [[Circulatory system|circulation]]. | ||
*There are weak points, or "watershed" areas, at the borders of the territory supplied by each of these arteries. | *There are weak points, or "[[Watershed Area (medical)|watershed]]" areas, at the borders of the territory supplied by each of these [[Artery|arteries]]. | ||
**These watershed areas are most vulnerable to ischemia when blood flow decreases, as they have the fewest vascular collaterals. | **These [[Watershed Area (medical)|watershed]] areas are most vulnerable to [[ischemia]] when [[blood]] flow decreases, as they have the fewest [[vascular]] collaterals. | ||
* [[Rectum]] receives blood from the [[inferior mesenteric artery]] and the [[internal iliac artery]] | * [[Rectum]] receives [[blood]] from the [[inferior mesenteric artery]] and the [[internal iliac artery]] | ||
**Rectum is rarely involved by colonic ischemia due to this dual blood supply. | **[[Rectum]] is rarely involved by colonic [[ischemia]] due to this dual [[blood]] supply. | ||
===Development of Ischemia=== | ===Development of Ischemia=== | ||
* | * [[Colon (anatomy)|Colon]] receives between 10% and 35% of the total [[cardiac output]]. | ||
*If blood flow to the colon drops by more than about 50%, ischemia will develop. | *If [[blood]] flow to the colon drops by more than about 50%, [[ischemia]] will develop. | ||
* The arteries feeding the colon are very sensitive to [[vasoconstrictors]] | * The [[Artery|arteries]] feeding the [[Colon (anatomy)|colon]] are very sensitive to [[vasoconstrictors]] | ||
** During periods of [[hypotension|low blood pressure]], the arteries feeding the colon clamp down vigorously. | ** During periods of [[hypotension|low blood pressure]], the [[Artery|arteries]] feeding the [[Colon (anatomy)|colon]] clamp down vigorously. | ||
* | * [[Vasoconstriction|Vasoconstricting]] drugs such as [[ergotamine]], [[cocaine]], or [[vasopressor]]s can also cause colonic [[ischemia]].. | ||
** | ** Result in non-occlusive [[Ischemia|ischemic]] colitis. | ||
===Microscopic Pathology=== | ===Microscopic Pathology=== | ||
* A range of pathologic findings are seen in ischemic colitis, corresponding to the spectrum of clinical severity. | * A range of pathologic findings are seen in ischemic colitis, corresponding to the spectrum of clinical severity. | ||
** | ** Mildest form, [[Mucous membrane|mucosal]] and [[Submucosa|submucosal]] [[hemorrhage]] and [[edema]] are seen, possibly with mild [[necrosis]] or [[ulceration]]. | ||
** With more severe ischemia, a pathologic picture resembling [[inflammatory bowel disease]] (i.e. chronic [[ulcerations]], [[crypt abscess]]es and [[pseudopolyps]]) may be seen. | ** With more severe [[ischemia]], a pathologic picture resembling [[inflammatory bowel disease]] (i.e. chronic [[ulcerations]], [[crypt abscess]]es and [[pseudopolyps]]) may be seen. | ||
** In the most severe cases, transmural [[infarction]] with resulting perforation may be seen. | ** In the most severe cases, transmural [[infarction]] with resulting [[perforation]] may be seen. | ||
** After recovery, the muscularis propria may be replaced by fibrous tissue, resulting in a [[stricture]]. | ** After recovery, the [[Muscularis mucosae|muscularis]] propria may be replaced by [[Fibrous connective tissue|fibrous tissue]], resulting in a [[stricture]]. | ||
** Following restoration of normal blood flow, [[reperfusion injury]] may | ** Following restoration of normal blood flow, [[reperfusion injury]] may contribute to the damage to the [[Colon (anatomy)|colon]]. | ||
====Images==== | ====Images==== | ||
Revision as of 14:43, 9 January 2018
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Hamid Qazi, MD, BSc [2]
Overview
Ischemic colitis is the result of a sudden, temporary, reduction in blood flow that is insufficient to meet the metabolic demands of the region of colon. Ischemic change will subsequently extend from the mucosa to the serosa. Mucosal injury will develop in 20 minutes to 1 hour, and transmural infarction occurs within 8 to 16 hours. Reperfusion injury can occur with the release of reactive oxygen species, which cause lipid peroxidation within cell membranes, causing cell necrosis.
Pathophysiology
The pathophysiology of ischemic colitis is as follows:[1][2][3][4]
Colonic Blood Supply
- Colon receives blood from the superior and inferior mesenteric arteries.
- Blood supply from these arteries overlap, with abundant collateral circulation.
- There are weak points, or "watershed" areas, at the borders of the territory supplied by each of these arteries.
- Rectum receives blood from the inferior mesenteric artery and the internal iliac artery
Development of Ischemia
- Colon receives between 10% and 35% of the total cardiac output.
- If blood flow to the colon drops by more than about 50%, ischemia will develop.
- The arteries feeding the colon are very sensitive to vasoconstrictors
- During periods of low blood pressure, the arteries feeding the colon clamp down vigorously.
- Vasoconstricting drugs such as ergotamine, cocaine, or vasopressors can also cause colonic ischemia..
- Result in non-occlusive ischemic colitis.
Microscopic Pathology
- A range of pathologic findings are seen in ischemic colitis, corresponding to the spectrum of clinical severity.
- Mildest form, mucosal and submucosal hemorrhage and edema are seen, possibly with mild necrosis or ulceration.
- With more severe ischemia, a pathologic picture resembling inflammatory bowel disease (i.e. chronic ulcerations, crypt abscesses and pseudopolyps) may be seen.
- In the most severe cases, transmural infarction with resulting perforation may be seen.
- After recovery, the muscularis propria may be replaced by fibrous tissue, resulting in a stricture.
- Following restoration of normal blood flow, reperfusion injury may contribute to the damage to the colon.
Images
Micrograph of a colonic pseudomembrane, a finding that may be associated with ischemic colitis. H&E stain.
Videos
{{#ev:youtube|LCwMQU7ylYg}}
References
- ↑ Rosenblum JD, Boyle CM, Schwartz LB (1997). "The mesenteric circulation. Anatomy and physiology". Surg Clin North Am. 77 (2): 289–306. PMID 9146713.
- ↑ Granger DN, Rutili G, McCord JM (1981). "Superoxide radicals in feline intestinal ischemia". Gastroenterology. 81 (1): 22–9. PMID 6263743.
- ↑ Brandt LJ, Boley SJ, Goldberg L, et al: Colitis in the elderly. Am J Gastroenterol 76:239, 1981.
- ↑ Washington, Christopher; Carmichael, Joseph (2012). "Management of Ischemic Colitis". Clinics in Colon and Rectal Surgery. 25 (04): 228–235. doi:10.1055/s-0032-1329534. ISSN 1531-0043.