1. Acute Mesenteric Ischemia and Infarction
Dr. Sajad Ali (MBBS., MS.)
Gastrointestinal & Laparoscopic surgeon
Dr Ahmed Abanamy Hospital

2. 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.

3. Superior Mesenteric Artery (SMA)
Largest caliber vessel + 45-degree angle makes it most commonly occluded
Aorta
Celiac Trunk
SMA
IMA

4. 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

5. 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

6. Etiologies of Acute Mesenteric Ischemia (AMI)
Focal small bowel ischemia - rare
Partial malrotation, volvulus, mesenteric hematoma, strangulated hernia
Unknown
?Mesenteric small vessel disease

7. 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

8. 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

9. History & Physical Mesenteric Venous Thrombosis: Fever
Abdominal distension
Hemoccult positive stool

10. 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

11. Radiology
Plain films – thumbprinting, thickened bowel (<40% 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

12. Differential Diagnosis
Other serious conditions to consider:
Pancreatitis
Acute Diverticulitis
Acute Cholecystitis
Small bowel obstruction
Perforation of a viscous
Ruptured aneurysm

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

14. 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 hours
Vasodilators and careful pressor use

15. A Word on Ischemic Colitis
Presentation: less & more focal pain (usually left-sided), more bloody diarrhea, >90% 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