Ischemic Bowel Disease:
Ischemia means decrease in blood supply (blood flow) to an organ, tissue or part of the body. For example cerebral ischemia means decrease in blood supply to brain.
Maintenance of adequate blood flow is very important for correct and functioning and survival of an organ.
Adequate blood supply provides oxygen and nutrients to the tissue and also removes waste materials from the site of formation. In adequate blood flow or ischemia compromises the function of the organ because organ is not getting enough nutrients and accumulation of toxic wastes destroy the function of organ. If blood supply continues to decrease and ischemia is not correct, the organ may die.
Maintenance of adequate blood flow is important. Because in some cases there is normal arterial blood supply but there is obstruction in venous return. Therefore, blood won't flow through the vessels and this also results in ischemia.

Ischemic bowel disease, is the disease of bowel (intestine) or pathological changes in intestines that results from ischemia (decreased blood supply).

Intestinal Blood Supply:


Arterial Blood Supply:

lCoeliac artery
first portion of the duodenum
lSuperior mesenteric artery
the remainder of the small bowel and the large bowel up to the splenic flexure
lInferior mesenteric artery –
the remainder of the large bowel and part of the rectum
lBranches of the internal iliac artery

- distal rectum


Venous Drainage
The hepatic portal circulation carries venous blood from the gastrointestinal organs and spleen to the liver.
Eventually, blood leaves the sinusoids of the liver through the hepatic veins which drain into the inferior vena cava.
Predisposing Factors:

lAge (older than 50)
lMore frequent in women
lHigh blood pressure (hypertension).
lDiabetes
lHigh cholesterol
lSmoking
lHistory of heart attack
lStroke


Causes:
        vascular occlusion (Arterial)

lAtherosclerosis.
lAortic aneurysm.
lEmbolization of cardiac vegetations or aortic atheromas.

vascular occlusion (Venous)
lHypercoagulable states.
lInvasive neoplasms.
lCirrhosis.
lTrauma
lAbdominal masses compressing portal drainage.

Intestinal hypoperfusion.
lShock.
lDehydration.
lSystemic vasculitis

Pathogenesis:


lIschemic lesion may be restricted to the small or large intestine or may affect both, depending on the particular vessel or vessels involved.
lSeverity of ischemic damage also depends on time frame of occlusion (acute or chronic) and degree of vascular compromise.
lThe severity of injury ranges from:
lTransmural infarction of the gut, involving all visceral layers, to
lMural infarction of the mucosa and sub mucosa , sparing the muscular wall, to
lMucosal infarction, Just mucosa is involved
severity of infarction depends upon level of blood supply compromise.


Signs And Symptoms:

lNausea
lVomiting
lFatigue
lTransient bloody Diarrhea
lLow-grade fever
lAbdominal pain, tenderness
   or cramping 
lMinimal abdominal distention
lHypoactive bowel sound

Treatment
Treatment depends on cause of ischemic bowel disease.

Treatment options for mild ischemic bowel disease include:
Anticoagulant medications:
Heparin
Warfarin (Coumadin)
Angioplasty for bowel ischemia
To open the artery that supplies the intestine

Treatment options for life-threatening ischemic bowel disease include:
Papaverine injection for bowel ischemia
Dilates the arteries supplying blood to the intestine
Surgery for bowel ischemia:
To open the artery that supplies the intestine

References:
* Robins Basic Pathology
* Freemd.com
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