mesenteric vascular injury, vascular repair bowel ischemia

1. MANAGEMENT OF MESENTERIC
VASCULAR OCCLUSION
DR BASHIR BN YUNUS
GENERAL SURGERY UNIT
AKTH
20th Nov. 2017

2. OUTLINE
• INTRODUCTION
• DEFINITION
• EPIDEMIOLOGY
• ANATOMY
• TYPES
• MANAGEMENT
• RESUSCITATION
• DIAGNOSIS
• TREATMENT
• FUTURE TRENDS

3. INTRODUCTION
• Mesenteric vascular occlusion or mesenteric ischemia is a lethal
condition resulting from critically reduced perfusion to the GIT.
• Despite advances in vascular surgery, it still remains a complex and
disheartening disease with high mortality.
• It account for 1-2% of admissions for abdominal pain.
• Account for 9 in 100,000 persons per year, incidence increase with
age and its commoner in women.
• Mortality is 24-96 % with average of 69%.

4. ANATOMY OF MESENTERIC VASCULATURE
• Comprises of 3 major aortic branches with collaterals
• Celiac axis
• Superior mesenteric artery
• Inferior mesenteric artery
• Marginal Artery of Drummond – Anastomotic collateral between SMA
and IMA

5. ANATOMY

6. MESENTERIC VASCULATURE
• Celiac axis – foregut (distal esophagus to duodenum, hepatobiliary,
spleen)
• Left gastric artery
• Splenic artery
• Common hepatic artery

7. MESENTERIC VASCULATURE
• Superior mesenteric artery – midgut
• Inferior pancreaticoduodenal artery
• Jejunal branches
• Ileal branches
• Middle colic artery
• Right colic artery
• Ileocolic artery

8. MESENTERIC VASCULATURE
• Inferior mesenteric artery – hindgut
• Left colic artery
• Sigmoid arteries
• Superior rectal artery

15. TYPES
• ACUTE MESENTERIC ISCHEMIA
• Abrupt reduction in blood flow with threatened viability
• Emboli 50%
• Thrombosis 25%
• Non-occlusive 5-15%
• Mesenteric venous thrombosis 10%
• CHRONIC
• Gradual occlusion
• Vascular diseases

16. MANAGEMENT
• RESUSCITATION
• IV FLUIDS
• NG TUBE
• BROAD SPECTRUM ANTIBIOTICS
• ANALGESICS
• BLOOD TRANSFUSION
• MONITORING OF VITAL SIGNS

17. DIAGNOSIS
• Diagnosis is delayed in up to two-third of patient with mesenteric
ischemia.
• Outcome is related prompt diagnosis and initiation treatment

18. DIAGNOSIS
• HISTORY;
• ‘High index of suspicion’
• Classical- abdominal pain out of proportion to the findings on
physical examination and persisting beyond 2-3hours (spasms from
ischemia)
• Bleeding per rectum/ malena 15%
• Bilous vomiting
• Abdominal distention

19. • History of aetiology/risk factors;
• History suggestive of cardiac or vascular disease; cardiomyopathy, MI
• Non –occlusive; pancreatitis, sepsis, heart failure, burns, cardiac bypass,drugs
• Venous occlusion; hypercoagulable state, sepsis, pregnancy, malignancy
• Family history
• Smoking
• Hypertension
• Hypercholesterenemia

20. • Physical examination;
• Painful distress, may be pale, fever(advance disese), tarchycardia,
hypotension, irregular pulse(arrhythmia), cardiac murmurs
• distended abdomen, guarding, rigidity, rebound tendeness
• NB; normal abdomen in the face of severe abdominal pain in the
early stage.

21. INVESTIGATIONS
• Radiological; positive findings are usually late and non specific
• Plain andominal X-ray
• Majority of cases are Non diagnostic
• Dilated bowel loops
• Thumb printing
• Intramural gas
• Free air

25. • Ultrasonography – limited utility in acute mesenteric ischemia
• CT Scan;
• Dilatation of the bowel lumen
• Bowel wall thickening from oedema or hemorrhage
• Abnormal bowel wall enhancement, lack of enhancement indicate infarction
• Intraluminal thrombous
• Intralmural or portal venous gas

26. • Symmetrical bowel wall thickening greater than 3mm in a distended
segment of bowel suggests ischemia
• Greater degrees of bowel wall thickening should raise suspicion of
mesenteric venous thrombosis (MVT)
• Intravenous contrast is useful in demonstrating the heterogeneity of
the ischemic bowel wall (lack of bowel wall enhancement) and may
show occlusion of mesenteric arteries if given by rapid bolus
administration

28. • Sensitivity 64%
• Specificity 92%
• CT is the diagnosis technique of choice for acute MVT- sensitivity is
90%
• 3 D recon of the aorta and its branches show additional detail –
sensitivity and specificity to 94 to 96%
• The limitation and risk of CT angiography
• Renal insufficiency or contrast allergy
• Limitation of contrast volume and mental artefacts obscuring the area of
interest

31. ANGIOGRAPHY
• Definitive diagnosis - acute and chronic mesenteric ischemia.
• Arteriograms
• Establish the diagnosis
• Differentiate between acute embolic, thrombotic, or non-occlusive
mesenteric ischemia
• Allow proper planning of the revascularization procedure.
• AP and lateral views of the aorta and the mesenteric branches are required
for proper arteriographic evaluation.
• The lateral view is particularly important to examine the proximal celiac artery
and SMA, which overlap the aortic contrast column on AP views.

34. • Acute embolic occlusion of the SMA is abrupt occlusion of the artery,
usually at a branch point where the vessel tends to narrow
• If imaged acutely, a meniscus sign (crescent) is often observed.
• If secondary thrombosis occurs proximal to the embolus, the classic
meniscus sign of embolic occlusion will be obscured.

35. Advantages of angiography
• Dissolving a blood clot with agents
• Opening a partially blocked artery with a balloon
• Placing a small tube called a stent into an artery to help hold it open

39. Other investigations
• Blood
• Elevated WBC, anaemia
• Elevated amylase, phosphate,
• metabolic acidosis,
• INR,
• ECG.

40. TREATMENT
• Surgical treatment; surgery is the mainstay of treatment, medical
treatment with vasodilators, thrombolytics and anticoagulant are
used as adjuncts to surgery and endovascular therapy.
• Endovascular Treatment;

41. MEDICAL TREATMENT
• Vasodilators e. g Papaverine : is phosphodiesterase inhibitor, which
acts to relax vascular smooth muscle and causes vasodilation.
• Thrombolytics : The infusion must be started within 8 hours of
symptom onset. E.g urokinase, recombinant t- PA
• Anticoagulants; heparin and warfarin use in venous thrombosis and
post-operatively after embolectomy or bypass
• Antibiotics.
• Analgesics.

42. ENDOVASCULAR TREATMENT
• Interventional radiologist;
• Catheter directed thrombolytics/vasodilatation
• Angioplasty
• Stent insertion

43. ENDOVASCULAR TREATMENT
• Catheter-directed thrombolytic therapy is a potentially useful
treatment modality.
• Initiated with intra-arterial delivery of thrombolytic agent into the
mesenteric thrombus at the time of diagnostic angiography.
• Urokinase or recombinant tissue plasminogen activator have been
reported to be successful
• Catheter-directed thrombolytic therapy has a higher probability of
restoring mesenteric blood flow success when performed within 12
hours of symptom onset.

44. • Successful resolution of a mesenteric thrombus - facilitate the
identification of the underlying mesenteric occlusive disease process.
• Subsequent operative mesenteric revascularization or mesenteric
balloon angioplasty and stenting may be performed electively
• Main drawbacks
• Percutaneous, catheter-directed thrombolysis (CDT) does not allow the
possibility to inspect the potentially ischemic intestine following restoration
of the mesenteric flow.
• Prolonged period of time - achieve successful CDT,
• An incomplete or unsuccessful thrombolysis

45. Before and after angioplasty of SMA stenosis

46. SURGICAL TREATMENT
• Operative intervention remains the mainstay of management
• The surgeon's goal is to confirm the diagnosis
• Assess bowel viability,
• Determine the responsible etiology,
• Perform revascularization where possible
• Resect nonviable bowel

47. • Indications;
• Failed thrombolytic therapy- no evidence of reperfusion after 4 hours
• Presentation after 8 hours of onset of pain
• Features of peritonitis

49. SUPERIOR MESENTERIC ARTERY EMBOLECTOMY
• The abdomen is explored - midline incision - reveals variable degrees of
intestinal ischemia from the mid jejunum to the ascending or transverse
colon.
• The omentum and transverse colon are lifted cephalad.
• All small bowel is retracted to the right, and the sigmoid colon packed to
the left.
• The ligament of Treitz and the superior attachments of the duodenum are
sharply divided, with the goal of mobilizing the last portion of the
duodenum to the right.
• Then, with four fingers behind the small bowel mesentery and with the
thumb anteriorly, the SMA should be palpable near the base of the
transverse colon mesentery.

50. • Alternatively, after lifting the transverse colon, the SMA can also be
identified by following the middle colic artery until it enters the SMA
at the root of the mesentery.

51. • The SMA has a larger caliber proximal to the middle colic origin, making for
technically easier arteriotomy.
• Once the proximal SMA is identified it is controlled with vascular clamps,
• An approximately 3-4 cm length of artery is exposed and
vessel loops placed for proximal and distal control.
• A transverse arteriotomy may be used.
• Fogarty balloon catheter embolectomy is performed both proximally and
distally.
• Good back-bleeding and inflow suggest that the entire embolus has been
removed
• Bowel resection is performed as appropriate. A second-look exploration, 24-
48 hours following embolectomy, should be considered in many patients.

52. SMA embolectomy.
(a)Location of embolus within SMA is identified.
(b)Transverse or longitudinal arteriotomy is performed, and embolus is
extracted with balloon catheter.
(c)Arteriotomy is closed. Primary closure suffices for transverse arteriotomy, but vein patch is usually required
for closure of longitudinal arteriotomy

54. • Following the restoration of SMA flow,
• Assessment of intestinal viability must be made,
• Nonviable bowel must be resected.
• Several methods
• Intraoperative IV fluorescein injection and inspection with a Wood's lamp
• Doppler assessment of antimesenteric intestinal arterial pulsations.
• A second-look procedure - 24 to 48 hours following embolectomy.
• The goal of the procedure is reassessment of the extent of bowel
viability, which may not be obvious immediately following the initial
embolectomy.

56. SMA BYPASS
• Thrombotic mesenteric ischemia - severely atherosclerotic vessel
• Typically the proximal SMA.
• Require a reconstructive procedure to the SMA to bypass the
proximal occlusive lesion and restore adequate mesenteric flow.
• The saphenous vein is the graft material of choice
• Prosthetic materials should be avoided in patients with nonviable
bowel, due to the risk of bacterial contamination if resection of
necrotic intestine is performed.

57. • Bypass grafting types:
• Antegrade from supraceliac aorta
• Retrograde from infrarenal aorta

58. SMA bypass: antegrade.
Shown is bypass from supraceliac aorta to SMA alone (a)or to hepatic
artery and SMA (b)

60. RETROGRADE BYPASS

61. • Retrograde bypass is performed by first identifying a soft
portion of the distal aorta or common iliac artery.
After completion of the distal SMA anastomosis, the conduit
is stretched to lie taut along the left side of the aorta and
proximal anastomosis is performed.
• The graft should lie with a fair amount of tension to avoid laxity and
kinking.
• In retrograde bypass the limited dissection and avoidance of supraceliac
aortic occlusion make this option attractive

62. FUTURE DIRECTION
• Intestinal ischemia results in formation of free radicals
• Free radicals promote systemic release of bacterial toxins
• Systemic release of toxins leads to pulmonary complications
and distant organ disease.
• Various medications and hyperbaric oxygen continue being
studied to limit this form of injury- ISCHEMIC REPERFUSION
INJURY

63. Conclusion
• The management of mesenteric vascular occlusion is challenging even
in areas with improved facilities. High index of suspicion, early
detection, aggressive resuscitation and restoration of blood flow are
paramount for successful outcome.

64. References
• Micheal J, Stanley W. “Maingot’s Abdominal Operations”. Twelfth
edition. The McGraw-Hill companies, 2013.
• Andrew B. Mesenteric Ishemia; Ghana Emergency Medicine
Collaborative. michigan@umich.edu.
• www.slideshare .net
• E.A Badoe et al, “Principles and Practice of surgery including
pathology in the tropics” 4th edition, Assembly of God Literature
Center ltd, 2009
• Sriram Bhat S “SRB manual of surgery” 4th edition Jaypee Brothers
Medical Publishers (P) Ltd