This document provides an overview of mesenteric ischemia, including its various types, risk factors, clinical features, diagnosis, and management. It begins with definitions of relevant terms like ischemia, infarction, embolism, and thrombosis. It then describes the different types of mesenteric ischemia - acute, chronic, and non-occlusive. For each type, it outlines typical causes, risk factors, clinical presentations, diagnostic approaches, and treatment options, which may involve endovascular or open surgical revascularization procedures. It concludes by noting the generally poor prognosis of acute mesenteric ischemia but improved outcomes with timely diagnosis and treatment.

1. Mesenteric Ischemia
Prepared by
Pranjal Rokaya
Resident
General Surgery
KIST MCTH
18th September, 2022

2. Outline
• Terminologies
• Blood supply of gut
• Introduction and classification
• Clinical features
• Diagnosis
• Management
• Prognosis

3. Basics
a. Hemostasis: Process that maintain
blood in fluid, clot free state , while
rapidly forming hemostatic plug at site of
vascular injury.
b. Thrombosis: Formation of blod clot
within intact vessels

4. c. Embolism
An embolus is an intravascular solid, liquid, or gaseous mass that is carried by the
blood to a site distant from its point of origin.
• Thrombus : Thromboembolus
• Tissue : Amniotic fluid, Tumor cells
• Lipids : Fat embolism, Atheromatous embolism
Both thrombus and embolus cause tissue injury by vascular occlusion.

5. d. Ischemia
• Reduced blood flow to the tissue.
e. Infarction
• An infarct is an area of ischemic necrosis caused by occlusion of either arterial
supply or venous drainage.

6. Arterial supply of gut

7. Overview of arterial circulation of gut

8. Arterial supply of small intestine

9. Arterial supply of colon and rectum

10. Venous drainage of gut

11. Venous drainage of small intestine

12. Venous drainage of colon and rectum

14. Introduction
• Vasocclusive disease of mesenteric vessels.
• More common in older age (>60 years) and females (3 times more frequent).
• Relatively uncommon but devastating condition.
• Represents 2% of revascularisation operations for atheromatous lesions.

15. Risk factors
Embolism Thrombosis
1. Cardiac arrthmias 1. Coronary artery disease
2. Valvular heart disease 2. Peripheral arterial disease
3. Recent myocardial infarction 3. Advance age
4. Infective endocarditis 4. Low cardiac output states
5. Aortic atherosclerosis 5. Traumatic injury
6. Cardiogenic shock 6. Acquired hypercoagulable states:
COVID-19

16. Types of Mesenteric occlusive diseases
a. Acute mesenteric ischemia
b. Chronic mesenteric ischemia
c. Non occlusive mesenteric Ischemia (NOMI)

17. a. Acute Mesenteric Ischemia
Sudden onset of small intestine hypoperfusion.
Arterial occlusion in 67 to 95% of cases.
SMA is most commonly involved.
Acute thrombotic obstruction with underlying atherosclerosis: usually involves
origin of artery.
Acute embolism: usually at the branching point of an artery.

18. Clinical features
Severe periumbilical abdominal pain.
Out of proportion to physical findings (No signs of peritonism).
Nausea, vomiting and diarrhea.
Blood in stool in advanced ischemia.
Peritonism develops in advanced stage.

19. b. Chronic mesenteric Ischemia
 Intestinal angina
Episodic or continuous hypoperfusion of small intestine occuring in patient
with multivessel mesenteric artery stenosis or occlusion.
Majority caused by atherosclerotic narrowing of origins of CA or SMA.
 Rare causes include fibromuscular dysplasia, aortic or mesenteric artery
dissection, vasculitis, Takayasu disease.

20. Clinical features
 Most asymptomatic due to extensive collateral blood supply.
 Reccurent episodes of acute abodminal pain after eating.
 Pain usually subsides over 2 hours.
 Adaptive eating pattern
Weight loss
Acute on chronic ischemia

21. c. Non occlusive mesenteric ischemia
 Most commonly due to primary mesenteric arterial vasoconstriction.
The majority includes spasms of branches of SMA.
Related to the homeostatic mechanism that maintains cardiac and cerebral blood
flow at expense of mesenteric circulation.
Represents 5-15% of mesenteric ischemia.

22. Risk factors
 Heart failure/Cardiogenic shock
 Peripheral arterial disease
 Aortic insufficiency
 Septic shock
 Cardiac arrhythmias
 Administration of vasoconstrictive medication.
 Cocaine abuse.
 Severe burns
 Severe acute pancreatitis

23. Clinical features
• Location and severity of abdominal pain more variable.
• Mild abdominal pain a/w nausea/vomittting.
• Presentation overshadowed by precipitating disorders.
• Mental status changes in 1/3rd of old patients.

24. Physical examination
• Abdominal examination normal initially or only mild distension.
• Signs of peritoneal inflammation absent with ischemia alone.
• If infarction develops, peritoneal signs, distended abdomen and ileus develops.

25. Diagnosis
• Clinical suspicion in all patients with risk factors.
• Complete blood count
• Arterial blood gas
• Serum amylase
• Renal function test and lactate level.
• Patients with peritonitis or bowel perforation, diagnosis in OT.

26. Plain radiograph

27. Duplex Ultrasonography
No invasive means of assessing patency of mesenteric vessels.
Peak systolic velocity in SMA >275 cm/s: 92% sensitivity, 96% specificity for
detecting >70% stenosis.
Used for followup after successful surgical/endovascular treatment.
Sensitivity limited for detecting distal emboli or NOMI.

28. Advance abdominal imaging
 CT angiography or MR angiography 1st line for a definite diagnosis.
CT is performed without oral contrast as it can obscure mesenteric vessels and
bowel wall enhancement.
MRA is more sensitive; ideal for patients with allergies.
CT can show focal or segmental bowel wall thickening, intestinal pneumatosis,
bowel dilatation, or solid organ infarction.
Lack of enhancement of arterial vasculature with contrast.

29. Pneumatosis coli

30. Acute thrombosis with calcification

31. 3 vessel disease in aortography

32. Nonocclusive ischemia

33. Management
a. Gastrointestinal decompression
• NG tube placement
b. Fluid resuscitation
c. Hemodynamic monitoring and support
• Vasoconstricting agents and digitalis avoided
• Dobutamine or low-dose dopamine.

34. d. Correction of electrolyte abnormalities
e. Pain control
• Typically with parenteral opiods.
f. Broad spectrum antibiotics
G. Anticoagulation

35. Revascularisation
Endovascular techniques
Open techniques
• Depends on the acuity of presentation, etiology, and lesion
characteristics.
• Usually, open techniques for acute mesenteric ischemia and
endovascular for chronic cases.

36. 1. Endovascular approach
a.Mesenteric stenting
For patients with CMI, revascularisation of SMA main goal.
Ballon expandable covered stents are used due to better patency, fewer chances
of restenosis, and symptom recurrence.
b. Mechanical thrombectomy and lysis
c. Retrograde open mesenteric stenting
In CMA, if long segment disease or excessive calcification; a hybrid approach used

37. 2. Open approach
• Prepared from nipples to knee to allow possible saphenous or femoral vein harvest.
• NG tube placed.
• Entire bowel length evaluated but ischemic bowel not resected prior to
revascularization.
• Following revascularisation, retroperitoneal tissues are approximated to provide
layer between the intestine and graft.

38. Open approaches
a. SMA embolectomy
After adequate exposure, SMA opened transversely or longitudinally.
Thrombectomy is performed using Fogarty catheters sized to the diameter
of vessel.
Passed retrograde and antegrade until clean pass made.
Transverse arteriotomy closed with interrupted suture.
Longitundinal requires patch closure.

39. Open approaches
b. Mesenteric artery bypass
Use inflow from supraceliac aorta or distal aorta/ iliac arteries.
For SMA revascularisation, anastomosis placed just distal to the origin of middle
colic artery.
Saphenous or femoral vein may be harvested for bypass conduit.

40. Abdominal exploration
• Should not be delayed in patients suspected
of having intestinal infarction or perforation.
• Rexploration is 24-48 hours, may need
multiple laparotomies.

41. Viability of gut
Other techniques: Doppler exam, flourescein, perfusion flourometers, indocyanine green

42. Treatment of NOMI
• Remove inciting factors
• Treat underlying causes.
• Hemodynamic support and monitoring.
• Vasodilator(eg. Papaverine, prostaglandin, nitroglycerin), only intervention
available.
• Given through arteriographic cathetar placed in SMA.
• Abdominal exploration.

43. Prognosis
• Mortality exceeds 60% for acute mesenteric ischemia.
• Survival is worst for patients with arterial etiology.
• May suffer from short bowel syndrome.
• Long term dependence on TPN.

44. References
• Bailey and love textbook of surgery, 27th edition.
• Schwartz textbook of surgery, 11th edition.
• Uptodate

45. Thank You.