Intestinal Ischemia
Michele Young, MD
Chief GI Phoenix VA Hospital
Banner/VA GI Fellowship
Program Director
Outline
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Types
Anatomy
Pathophysiology
Acute Mesenteric Ischemia
Mesenteric Vein Thrombosis
Focal Segmental Ischemia
Colon Ischemia
Chronic Mesenteric Ischemia
Vasculitides
Types
TYPE
FREQUENCY (%)
Colon ischemia
75
Acute mesenteric ischemia
25
Focal segmental ischemia
<5
Chronic mesenteric ischemia
<5
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
Anatomy – Celiac Axis
Anatomy – Superior Mesenteric Artery
(SMA)
• Anterior and posterior inferior
pancreaticoduodenal
• Middle colic
• Right colic
• Ileocolic
Anatomy - SMA
Anatomy – Inferior Mesenteric Artery
(IMA)
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Left colic
Sigmoid branches
Superior rectal
Supply distal transverse to proximal rectum
Distal rectum: internal iliac
Anatomy - IMA
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
Acute Mesenteric Ischemia
CAUSE
FREQUENCY (%)
SMA embolus
50
Nonocclusive mesenteric ischemia
25
SMA thrombosis
10
Mesenteric venous thrombosis
10
Focal segmental ischemia
5
Clinical Features
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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
Diagnosis
• Labs
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75% have WBC > 15
50% have metabolic acidosis
• Plain films
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Poorly sensitive (30%) and nonspecific
Formless loops of small intestine
Ileus, thumbprinting, pneumatosis
Portal or mesenteric vascular gas
• CT
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Colon dilatation
Bowel wall thickening
Lack of enhancement of arterial vasculature
Ascites
• CT angiography
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Better evaluation of vessels
• Selective mesenteric angiography
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Gold standard
• Prompt laparotomy if angiography not available
Portal Gas
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
SMA Embolus
Pre and post treatment
Treatment
• Nonocclusive Mesenteric Ischemia
▫ Vasoconstriction from preceding cardiovascular
event
▫ Angiography
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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
NOMI
Pre and post treatment
Treatment
• Acute Superior Mesenteric Artery Thrombosis
▫ Severe atherosclerotic narrowing
▫ Often superimposed on chronic mesenteric
ischemia
▫ Demonstrated on aortography
▫ Management same as SMA embolism
Mesenteric Vein Thrombosis
• Age: mid-60s to 70s
• 20% mortality
• Manifest as colon ischemia, acute mesenteric
ischemia, or focal segmental ischemia
• Causes
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Arterial hypertension
Neoplasms
Coagulation disorders
Estrogen
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
Mesenteric Vein Thrombosis
• Subacute
▫ Abdominal pain for weeks to months but no
infarction
• Chronic
▫ Asymptomatic
▫ May develop GI bleeding from varices
▫ Treatment: control bleeding
Focal Segmental Ischemia
• Involves small bowel
• Causes
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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
Focal Segmental Ischemia
• Radiologic studies
▫ Smooth tapered stricture
▫ Abrupt change to normal distally
▫ Dilated proximally
• Treatment: resection
Colon Ischemia
TYPE
Reversible colopathy and transient colitis
FREQUENCY (%)*
>50
Transient colitis
10
Chronic ulcerating colitis
20
Stricture
10
Gangrene
15
Fulminant universal colitis
<5
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
Medications
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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
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
Clinical Features
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Sudden cramping
Mild left lower quadrant pain
Urgent desire to defecate
Hematochezia within 24 hours
Location:
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Sigmoid 23%
Descending-to-sigmoid 11%
Cecum-to-hepatic flexure 8% (worse prognosis)
Descending 8%
Pancolonic 7%
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
Colonoscopy
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
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
Chronic Mesenteric Ischemia
• “Intestinal angina”
• Mesenteric atherosclerosis
• Pain from small bowel ischemia
▫ Blood stolen to meet increased gastric demand
from food
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
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
Treatment
• Revascularization
▫ Need occlusive involvement of ≥2 major arteries
▫ Surgical if healthy
▫ Otherwise percutaneous +/- stent