class room lecture

1. Acute Mesenteric
Ischemia and Infarction
Dr. Muhammad Noman Rashid
Senior Registrar
Department of Interventional Cardiology
Ziauddin Medical University 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
Celiac Trunk
IMA
SMA
Aorta

4. Superior Mesenteric Artery (SMA)
 Emboli occlude past the middle colic,
causing small bowel ischemia
SMA
Middle Colic
Right Colic
Ileocolic
Jejunal & Ileal
Arteries
Occlusion
Point

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 24-48 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

16. References
 Netter FH, Atlas of Human Anatomy
 Oldenburg et al. Arch Intern Med 164:1054 2004
 Scott JR et al. AJR 113:2 “Acute Mesenteric
Infarction” 1971
 UptoDate Online: Article on “Acute Mesenteric
Ischemia”
 UptoDate Online: Article on “Ischemic colitis”