Acute mesenteric ischemia and infarction can result from ischemia or reduced blood flow to the small bowel or colon. The most common cause is occlusion of the superior mesenteric artery, often due to embolism from heart conditions. Clinical presentation involves severe abdominal pain, nausea, and vomiting. Diagnosis relies on blood tests, imaging like CT scan, and mesenteric angiography. Treatment requires resuscitation followed by efforts to restore blood flow surgically or with medications, and resection of any infarcted tissue.

1. Acute MesentericAcute Mesenteric
Ischemia and InfarctionIschemia and Infarction
Dr. Sajad Ali (MBBS., MS.)Dr. Sajad Ali (MBBS., MS.)
Gastrointestinal & LaparoscopicGastrointestinal & Laparoscopic
surgeonsurgeon
Dr Ahmed Abanamy HospitalDr Ahmed Abanamy Hospital

2. A First Big Distinction…A First Big Distinction…
 Mesenteric IschemiaMesenteric Ischemia – ischemia of the– ischemia of the
small bowelsmall bowel, usually 2/2 an acute cause, usually 2/2 an acute cause
involving the SMA or SMV.involving the SMA or SMV.
 Ischemic colitisIschemic colitis – ischemia of the– ischemia of the coloncolon,,
rarely with a known acute precipitatingrarely with a known acute precipitating
cause.cause.

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

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

5. Etiologies of Acute MesentericEtiologies of Acute Mesenteric
Ischemia (AMI)Ischemia (AMI)
 SMA Occlusion (at least 60% of cases)SMA Occlusion (at least 60% of cases)
 Embolism: MI, Afib, Endocarditis, Valve d/oEmbolism: MI, Afib, Endocarditis, Valve d/o
 Thrombosis: Atherosclerosis – plaque ruptureThrombosis: Atherosclerosis – plaque rupture
 Nonocclusive Mesenteric IschemiaNonocclusive Mesenteric Ischemia
(NOMI)(NOMI)
 Atherosclerosis + shock + vasopressorsAtherosclerosis + shock + vasopressors
 Mesenteric Venous Thrombosis (MVT)Mesenteric Venous Thrombosis (MVT)
 Primary clotting disorderPrimary clotting disorder

6. Etiologies of Acute MesentericEtiologies of Acute Mesenteric
Ischemia (AMI)Ischemia (AMI)
 Focal small bowel ischemia - rareFocal small bowel ischemia - rare
 Partial malrotation, volvulus, mesentericPartial malrotation, volvulus, mesenteric
hematoma, strangulated herniahematoma, strangulated hernia
 UnknownUnknown
 ?Mesenteric small vessel disease?Mesenteric small vessel disease

7. History & PhysicalHistory & 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 & PhysicalHistory & Physical
SMA Thrombosis:SMA Thrombosis:
 Prodrome of postprandial pain/nauseaProdrome of postprandial pain/nausea
and weight lossand weight loss
 Presentation with classic symptomsPresentation with classic symptoms
Non-occlusive Mesenteric Ischemia:Non-occlusive Mesenteric Ischemia:
 Unexplained decline in clinical status orUnexplained decline in clinical status or
failure to follow expected recoveryfailure to follow expected recovery

9. History & PhysicalHistory & Physical
Mesenteric Venous Thrombosis:Mesenteric Venous Thrombosis:
 FeverFever
 Abdominal distensionAbdominal distension
 Hemoccult positive stoolHemoccult positive stool

10. Laboratory FindingsLaboratory Findings
 Anion gap metabolic acidosisAnion gap metabolic acidosis
 Elevated arterial/venous lactateElevated arterial/venous lactate
 LeukocytosisLeukocytosis
 HemoconcentrationHemoconcentration
 Elevated LDH, amylase, AST, and CPKElevated LDH, amylase, AST, and CPK
 Elevated K and Phos are late signsElevated K and Phos are late signs

11. RadiologyRadiology
 Plain films – thumbprinting, thickenedPlain films – thumbprinting, thickened
bowel (<40% sensitivity)bowel (<40% sensitivity)
 CT – thickened/dilated bowel, intramuralCT – thickened/dilated bowel, intramural
hematoma, pneumatosis (64% sensitivity)hematoma, pneumatosis (64% sensitivity)
 MRI – promising but untested to dateMRI – promising but untested to date
 Mesenteric angiography – test of choice;Mesenteric angiography – test of choice;
can identify the type of AMIcan identify the type of AMI

12. Differential DiagnosisDifferential Diagnosis
Other serious conditions to consider:Other serious conditions to consider:
 PancreatitisPancreatitis
 Acute DiverticulitisAcute Diverticulitis
 Acute CholecystitisAcute Cholecystitis
 Small bowel obstructionSmall bowel obstruction
 Perforation of a viscousPerforation of a viscous
 Ruptured aneurysmRuptured aneurysm

13. TreatmentTreatment
 Resuscitation with fluids/blood productsResuscitation with fluids/blood products
 AnticoagulationAnticoagulation
 Infusion of a vasodilatorInfusion of a vasodilator
 Glucagon systemically ORGlucagon systemically OR
 Papaverine through a catheterPapaverine through a catheter

14. From Ischemia to InfarctionFrom Ischemia to Infarction
 Marked by peritoneal signs, feverMarked by peritoneal signs, fever
 Emergent laporatomyEmergent laporatomy
 Restoration of interrupted blood flow withRestoration of interrupted blood flow with
arteriotomy or bypass graftarteriotomy or bypass graft
 Resection of infarcted bowelResection of infarcted bowel
 Second-look in 24-48 hoursSecond-look in 24-48 hours
 Vasodilators and careful pressor useVasodilators and careful pressor use

15. A Word on Ischemic ColitisA Word on Ischemic Colitis
 Presentation: less & more focal painPresentation: less & more focal pain
(usually left-sided), more bloody diarrhea,(usually left-sided), more bloody diarrhea,
>90% are over 60 years old.>90% are over 60 years old.
 Etiology rarely identified: ?small vesselEtiology rarely identified: ?small vessel
disease +/- hypoperfusiondisease +/- hypoperfusion
 Episodes usually self limited except whenEpisodes usually self limited except when
stricture or gangrene developsstricture or gangrene develops
 Colonoscopy is initial evaluation of choiceColonoscopy is initial evaluation of choice