Acute Mesenteric Ischemia and Infarction

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Acute Mesenteric Ischemia and Infarction

• Matthew Volk
• Morning Report
• 7/30/2008

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A First Big Distinction

• Mesenteric Ischemia ischemia of the small
  bowel, usually 2/2 an acute cause involving the
  SMA or SMV.
• Ischemic colitis ischemia of the colon, rarely
  with a known acute precipitating cause.

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Superior Mesenteric Artery (SMA)

• Largest caliber vessel 45-degree angle makes it
  most commonly occluded

Aorta
Celiac Trunk
SMA
IMA
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Superior Mesenteric Artery (SMA)

• Emboli occlude past the middle colic, causing
  small bowel ischemia

Middle Colic
SMA
Jejunal Ileal Arteries
Occlusion Point
Right Colic
Ileocolic
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Etiologies of Acute Mesenteric Ischemia (AMI)

• SMA Occlusion (at least 60 of cases)
• Embolism MI, Afib, Endocarditis, Valve d/o
• Thrombosis Atherosclerosis plaque rupture
• Nonocclusive Mesenteric Ischemia (NOMI)
• Atherosclerosis shock vasopressors
• Mesenteric Venous Thrombosis (MVT)
• Primary clotting disorder

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Etiologies of Acute Mesenteric Ischemia (AMI)

• Focal small bowel ischemia - rare
• Partial malrotation, volvulus, mesenteric
  hematoma, strangulated hernia
• Unknown
• ?Mesenteric small vessel disease

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History Physical

• Classic Presentation
• Rapid onset of severe, unrelenting periumbilical
  pain
• Pain out of proportion to findings on physical
  examination.
• Nausea and vomiting
• Forceful/urgent bowel evacuation
• Risk factors for acute mesenteric ischemia

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History Physical

• SMA Thrombosis
• Prodrome of postprandial pain/nausea and weight
  loss
• Presentation with classic symptoms
• Non-occlusive Mesenteric Ischemia
• Unexplained decline in clinical status or failure
  to follow expected recovery

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History Physical

• Mesenteric Venous Thrombosis
• Fever
• Abdominal distension
• Hemoccult positive stool

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Laboratory Findings

• Anion gap metabolic acidosis
• Elevated arterial/venous lactate
• Leukocytosis
• Hemoconcentration
• Elevated LDH, amylase, AST, and CPK
• Elevated K and Phos are late signs

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Radiology

• Plain films thumbprinting, thickened bowel
  (lt40 sensitivity)
• CT thickened/dilated bowel, intramural
  hematoma, pneumatosis (64 sensitivity)
• MRI promising but untested to date
• Mesenteric angiography test of choice can
  identify the type of AMI

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Differential Diagnosis

• Other serious conditions to consider
• Pancreatitis
• Acute Diverticulitis
• Acute Cholecystitis
• Small bowel obstruction
• Perforation of a viscous
• Ruptured aneurysm

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Treatment

• Resuscitation with fluids/blood products
• Anticoagulation
• Infusion of a vasodilator
• Glucagon systemically OR
• Papaverine through a catheter

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From Ischemia to Infarction

• Marked by peritoneal signs, fever
• Emergent laporatomy
• Restoration of interrupted blood flow with
  arteriotomy or bypass graft
• Resection of infarcted bowel
• Second-look in 24-48 hours
• Vasodilators and careful pressor use

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A Word on Ischemic Colitis

• Presentation less more focal pain (usually
  left-sided), more bloody diarrhea, gt90 are over
  60 years old.
• Etiology rarely identified ?small vessel disease
  /- hypoperfusion
• Episodes usually self limited except when
  stricture or gangrene develops
• Colonoscopy is initial evaluation of choice

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References

• Netter FH, Atlas of Human Anatomy
• Oldenburg et al. Arch Intern Med 1641054 2004
• Scott JR et al. AJR 1132 Acute Mesenteric
  Infarction 1971
• UptoDate Online Article on Acute Mesenteric
  Ischemia
• UptoDate Online Article on Ischemic colitis