3. Types
TYPE FREQUENCY (%)
Colon ischemia 75
Acute mesenteric ischemia 25
Focal segmental ischemia <5
Chronic mesenteric ischemia <5
4. Anatomy Celiac Axis
Supplies stomach, duodenum, pancreas, and
liver
Three branches: left gastric, common hepatic,
splenic
Common hepatic: gastroduodenal, right
gastroepiploic, anterior superior
pancreaticoduodenal
Splenic: pancreatic and left gastroepiploic
10. Pathophysiology
Bowel can tolerate 75% reduction of blood flow
and oxygen consumption for 12 hours
Collaterals open immediately
After hours, vasoconstriction reduces collateral
flow (NOMI)
Hypoxia, reperfusion injury
ROS by xanthine oxidase
Microvascular injury by PMNs
11. Acute Mesenteric Ischemia
CAUSE FREQUENCY (%)
SMA embolus 50
Nonocclusive mesenteric ischemia 25
SMA thrombosis 10
Mesenteric venous thrombosis 10
Focal segmental ischemia 5
12. Clinical Features
Acute abdominal pain in patient with CV risks
Rapid and forceful bowel evacuation (SMAE)
Pain out of proportion to exam
Some more indolent (MVT)
Unexplained abdominal distention (sign of
infarction) or GI bleeding (NOMI)
Physical findings worsen with progressive loss of
bowel viability
Infarction: 70-90% mortality
13. Diagnosis
Labs
75% have WBC > 15
50% have metabolic acidosis
Plain films
Poorly sensitive (30%) and nonspecific
Formless loops of small intestine
Ileus, thumbprinting, pneumatosis
Portal or mesenteric vascular gas
CT
Colon dilatation
Bowel wall thickening
Lack of enhancement of arterial vasculature
Ascites
CT angiography
Better evaluation of vessels
Selective mesenteric angiography
Gold standard
Prompt laparotomy if angiography not available
21. Treatment
General
Resuscitation, Broad-spectrum antibiotics
Superior Mesenteric Artery Embolus
Cardiac origin
Major: proximal to ileocolic
Intra-arterial papaverine
Surgical revascularization
Minor and no peritoneal signs
Intra-arterial papaverine (or thrombolytics)
Anticoagulation
23. Treatment
Nonocclusive Mesenteric Ischemia
Vasoconstriction from preceding cardiovascular
event
Angiography
Narrowing of SMA branch origins
Irregularities in intestinal branches
Spasm of arcades
Impaired filling of intramural vessels
SMA infusion of papaverine for 24 hours
Surgery if peritoneal signs are present
25. Treatment
Acute Superior Mesenteric Artery Thrombosis
Severe atherosclerotic narrowing
Often superimposed on chronic mesenteric
ischemia
Demonstrated on aortography
Management same as SMA embolism
26. Mesenteric Vein Thrombosis
Age: mid-60s to 70s
20% mortality
Manifest as colon ischemia, acute mesenteric
ischemia, or focal segmental ischemia
Causes
Arterial hypertension
Neoplasms
Coagulation disorders
Estrogen
27. Mesenteric Vein Thrombosis
Acute
Pain out of proportion to exam, n/v
Lower GI bleeding suggests infarction
Diagnosis
CT is study of choice (finds >90%)
Mesenteric arteriography
Slow or absent filling of mesenteric veins
Failure of arterial arcades to empty
Prolonged blush in involved segment
Treatment
Incidental: up to six months of anticoagulation (AC)
Peritonitis: surgery, papaverine, post-op heparin
No peritoneal signs: heparin followed by 3-6 mos AC
28. Mesenteric Vein Thrombosis
Subacute
Abdominal pain for weeks to months but no
infarction
Chronic
Asymptomatic
May develop GI bleeding from varices
Treatment: control bleeding
29. Focal Segmental Ischemia
Involves small bowel
Causes
Atheromatous emboli
Strangulated hernias
Immune complex disorders
Trauma
Segmental venous thrombosis
Radiation therapy
Oral contraceptives
Usually adequate collaterals to prevent infarction
Presentation: enteritis, stricture, acute abdomen
Chronic can resemble Crohn's
30. Focal Segmental Ischemia
Radiologic studies
Smooth tapered stricture
Abrupt change to normal distally
Dilated proximally
Treatment: resection
31. Colon Ischemia
TYPE FREQUENCY (%)*
Reversible colopathy and transient colitis >50
Transient colitis 10
Chronic ulcerating colitis 20
Stricture 10
Gangrene 15
Fulminant universal colitis <5
32. Colon Ischemia
Most common form of intestinal ischemia
7.2 cases per 100,000 person-years
Female predilection
Most > 60 years old
Young pt: vasculitis, coagulation disorders,
cocaine, medications
Right colon ischemia
May have small intestinal ischemia
34. Pathology
Mild: mucosal and submucosal hemorrhage and
edema
More severe: ulcerations, crypt abscesses,
pseudopolyps, pseudomembranes, iron-laden
macrophages, submucosal fibrosis (stricture)
Most severe: transmural infarction
35. Clinical Features
Sudden cramping
Mild left lower quadrant pain
Urgent desire to defecate
Hematochezia within 24 hours
Location:
Sigmoid 23%
Descending-to-sigmoid 11%
Cecum-to-hepatic flexure 8% (worse prognosis)
Descending 8%
Pancolonic 7%
36. Diagnosis
CT scan
If nonspecific, colonoscopy within 48 hours
Unprepped, low air
Colon single-stripe sign
Line of erythema with erosion or ulceration along
the longitudinal axis of the colon
Milder course
42. Treatment
NPO, IVF, antibiotics
EKG, Holter, echo
Colonic infarction
Laparotomy and resection
Serosa can be misleading
Segmental Ulcerating Colitis
Recurrent fevers and sepsis
Continuing or recurrent bloody diarrhea
Persistent or chronic diarrhea with protein-losing
colopathy
Treat by resection
43. Treatment
Ischemic Stricture
Dilation or resection
Universal Fulminant Colitis
Colectomy with ileostomy
Isolated Ischemia of the Right Colon
Check CTA for concurrent AMI
Carcinoma/Obstructive Lesions (<5%)
Lesion distal, increased intracolonic pressure proximal
Irritable Bowel Syndrome
Colon ischemia 3.4 to 3.9x more common
?Hypersensitivity of the colonic vasculature
Complicating Aortic Surgery
Up to 7% of surgeries (60% for ruptured aneurysm)
Colonoscopy within 2-3 days if high risk
Ex: ruptured aneurysm, prolonged cross-clamping time, post-op diarrhea
44. Chronic Mesenteric Ischemia
Intestinal angina
Mesenteric atherosclerosis
Pain from small bowel ischemia
Blood stolen to meet increased gastric demand
from food
45. Clinical Features
Gradual cramping discomfort within 30 minutes
of eating, resolves over hours
Fear of eating, weight loss
Nonhealing antral ulcers without H. pylori
1/3 to 遜: cardiac, cerebral, peripheral vascular
disease
Exam
Abdomen soft and nontender
Bruit common but nonspecific
46. Diagnosis
Gastric tonometry exercise testing (GET)
NG tube and arterial line
Patient on PPI
Obtain gastric juice and arterial blood fasting, during,
after exercise
Measure gastric-arterial PCO2 gradients
Increase after exercise indicates ischemia
Combine with duplex U/S
Angiography
Should show occlusion of 2 splanchnic arteries
Does not make diagnosis in itself
#9: AOR, arc of Riolan; ASC, ascending branch of the left colic artery; CA, central artery; DSC, descending branch of the left colic artery; LMC, left branch of middle colic artery; MA, marginal artery; MC, middle colic artery; RMC, right branch of middle colic artery; S, sigmoid branches; SR, superior rectal artery