Mesenteric vascular occlusion

mesenteric vascular injury, vascular repair bowel ischemia

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

9. 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

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

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

12. 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

13. 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

14. 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.

15. 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

16. 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

17. 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

18. 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

19. 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.

20. 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.

21. 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

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

23. 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;

24. 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.

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

26. 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.

27. 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

28. Before and after angioplasty of SMA stenosis

29. 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

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

31. 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 .

32. 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.

33. 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.

34. 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

35. 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.

36. 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.

37. Bypass grafting types: Antegrade from supraceliac aorta Retrograde from infrarenal aorta

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

39. RETROGRADE BYPASS

40. 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

41. 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

42. 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.

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