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home - Colon - Colonic Vascular Disorders - Ischaemia Written by Dr Sebastian Zeki

Ischaemia

Mesenteric arterial thrombosis (20%) Acute episodes often occur in the context of chronic mesenteric ischaemia or with trauma/ infection.SMA/coeliac axis thrombosis usually occurs at the vessel origin and involves at least 2 major splanchnic arteries, which may complicate attempts at revascularization. Treatment— Mortality of 70%.Papaverine thru’ angiographic catheter.Rpt angiography in 24 hrs to confirm resolution. Sometimes also give heparin.If peritoneal signs- surgery with pre and post-op papaverine Diagnosis:Labs: Lactate - 100 % se/42 % spec./Amylase inc in 50%/ LDH 73% se but doesnt distinguish ischaemia from infarction/ WCC > 20,000 µL and metabolic acidosis in context of colitis very suggestive of ischaemia Acute mesenteric ischemia Risk Factors:Old age; Atherosclerosis; Low cardiac output states; Arrhythmias; Severe cardiac valvular disease;Recent MI; Intra-abdominal malignancy. Rapid onset severe periumbili-cal abdominal pain, out of proportion to physical N&V common. 50% N&VOesophageal/gastric varices due to concomi-tant portal or splenic v. thrombosis.Mesenteric v. thrombosis may have symptoms from wks to mnths 1 2 3 4 Complications:1. Resistance in mesenteric v. blood flow2. Then bowel wall edema with fluid efflux into the bowel lumen (3.)4. Resulting systemic hypotension+ inc blood viscosity with reduced art. flow (5), submucosal hemorrhage and bowel infarction(6) 5 Risk factors Hypercoagulable states (factor V Leiden deficient 50%, 10% Protein S, protein C, and antithrombin (AT) 4% Antiphospholipid antibodies.)Hypercoagulable diseases- most common is PNH and myeloproliferative disordersPortal hypertension; Abdominal infections; Blunt abdominal traumaPancreatitis; Splenectomy; Malignancy in the portal region. Prognosis — Survival at 3.5 years is around 82%. Treatment with beta blockers and anticoagulation assoc. with dec mortality. Infarction risk> GI blood loss so can have anticoagulation (even if bleeding)Intra SMA papaverine at angiography to reduce art spasm Anticoagulate for at least 6 months depending on cause If good mesenteric blood flow demonstrated by angiography and no peritoneal signs- observePeritoneal findings: SurgeryIf tissue viable but vein occluded then do thrombec-tomyPost op need heparin +/- thrombotic agents Splanchnic hypoper-fusion (from any cause of hypoperfu-sion) and vasocon-striction (eg cocaine/ alpha-adrenergic agonists) Villus tips are most vulnerable as high O2 requirement. Mesenteric vasospasm Often in SMA Mesenteric arterial embolism(50%) It is usually from the heart.15 % of emboli lodge in the origin of the SMA-(narrow take-off from aorta) lodging 3-10 cm distal to SMA origin, in a tapered segment distal to the take off of the middle colic artery.20% are multiple and complicated by vasoconstriction.Middle segment of the jejunum is most often involved as it is most distant from the collateral circulation of the celiac and inf mesenteric art. Nonocclusive mesenteric ischaemia(25%)25% have abdo pain (variable location) Treatment — Laparotomy with embolectomy and intra-op USS to identify ischaemic areasPostoperative papaverine reduces vasospasm.A "second-look" laparotomy within the next 24 to 48 hrsThrombolysis can sometimes be used.Warfarinise long term Treatment: Usually surgical.Thrombectomy with reconstructionIf no peritonism can use heparin infusion and observationCan use aspirin for long term mx Mesenteric venous thrombus (5%) Radiography— Mesenteric angiography = gold standard.Less sensitive for SMV thrombosis.Arteriography:NOMI:-Narrowing and irregularity in major branches-Decreased or absent flow in the smaller vessels-Absent submucosal "blush."Mesenteric venous thrombosis: venous filling defects or absent flow. X-ray:Normal in 25%- those with x-ray findings have a worse prognosisIleus with distended loops of bowel;Bowel wall thickening in 30%.;Pneumatosis intestinalis CT: Focal or segmental bowel wall thickening or intestinal pneumato-sis with PV. gas.Mesenteric arterial occlusions -lack of arterial enhancement Mesenteric venous thrombosis se.of 90 %. Treatment Written by Dr Sebastian Zeki

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