1. Intestinal Ischemia Michele Young, MD Chief GI Phoenix VA Hospital
Banner/VA GI Fellowship Program Director

2. Outline Types Anatomy Pathophysiology Acute Mesenteric Ischemia
Mesenteric Vein Thrombosis
Focal Segmental Ischemia
Colon Ischemia
Chronic Mesenteric Ischemia
Vasculitides

3. Types TYPE FREQUENCY (%) Colon ischemia 75 Acute mesenteric ischemia25
Focal segmental ischemia
<5
Chronic mesenteric ischemia

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

5. Anatomy – Celiac Axis
AIPD, anterior inferior pancreaticoduodenal artery; ASPD, anterior superior pancreaticoduodenal artery; CP, caudal pancreatic artery; DP, dorsal pancreatic artery; GD, gastroduodenal artery; H, common hepatic artery; LG, left gastric artery; PIPD, posterior inferior pancreaticoduodenal artery; PM, pancreata magna; RGE, right gastroepiploic artery; S, splenic artery; TP, transverse pancreatic artery.

6. Anatomy – Superior Mesenteric Artery (SMA)
Anterior and posterior inferior pancreaticoduodenal
Middle colic
Right colic
Ileocolic

7. Anatomy - SMA
AIPD, anterior inferior pancreaticoduodenal artery; COL, colic branches; IL, ileal branches; IC, ileocolic artery; JEJ, jejunal branches; MC, middle colic artery; PIPD, posterior inferior pancreaticoduodenal artery; RC, right colic artery.

8. Anatomy – Inferior Mesenteric Artery (IMA)
Left colic
Sigmoid branches
Superior rectal
Supply distal transverse to proximal rectum
Distal rectum: internal iliac

9. Anatomy - IMA
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

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
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 Plain films CT CT angiography
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

19. Portal Gas

21. Treatment General Superior Mesenteric Artery Embolus
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

22. SMA Embolus
Pre and post treatment

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

24. NOMI
Pre and post treatment

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
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

33. Medications Penicillins Alkaloid and taxanes
Constipation-Inducing Agents
Pseudoephedrine
Diuretics
Oral contraceptive pills
Amphetamines (R sided)
Cocaine (L sided)
Kayexelate
Magnesium citrate
Sodium phosphate
Bisacodyl
Glycerin enemas
NSAIDs
Sumatriptan
Alosetron

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

37. Colonoscopy

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 Universal Fulminant Colitis
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 ½: 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

47. Treatment Revascularization
Need occlusive involvement of ≥2 major arteries
Surgical if healthy
Otherwise percutaneous +/- stent