Acute Mesenteric Ischemia - Vascular Approach (WSES 2022)

Algorithm Steps

1. ▶

   Start

   Suspected Acute Mesenteric Ischemia

   Sudden severe abdominal pain out of proportion to physical findings

   1. ●

      Action

      Clinical Recognition

      High index of suspicion essential

      • Pain out of proportion to examination
      • Sudden onset severe abdominal pain
      • Risk factors: AF, recent MI, CHF, atherosclerosis
      • GI emptying (vomiting, bloody diarrhea)
      • Peritonitis = late sign (transmural necrosis)
      1. ●

         Action

         Immediate Resuscitation

         Start in parallel with workup

         • IV fluid resuscitation (crystalloid)
         • Correct electrolytes/acidosis
         • Broad-spectrum antibiotics
         • NG decompression
         • Avoid vasoconstrictors if possible
         • ICU admission
         1. ◆

            Decision

            Etiology Determination

            Guides treatment approach

            • Arterial embolism (~50%): AF, sudden onset, no prior symptoms
            • Arterial thrombosis (~25%): atherosclerosis, food fear, weight loss
            • Mesenteric venous thrombosis (~10%): hypercoagulable, portal HTN
            • NOMI (~15%): shock, vasoconstrictors, cardiac surgery
            1. ◆

               Decision

               Peritonitis or Bowel Necrosis?

               Determines operative approach

               • Peritoneal signs
               • Pneumatosis on CT
               • Portal venous gas
               • Severe metabolic acidosis
               • Hemodynamic instability
               1. ⚠

                  Warning

                  Emergent Laparotomy

                  Bowel necrosis requires surgical resection

                  • Resect non-viable bowel
                  • Assess viability: color, peristalsis, bleeding, fluorescence
                  • Revascularization + resection same procedure
                  • Damage control if unstable
                  • PLAN FOR SECOND-LOOK at 24-48h
                  1. ⚠

                     Warning

                     Second-Look Laparotomy

                     MANDATORY at 24-48 hours

                     • Assess bowel viability after reperfusion
                     • Resect additional non-viable bowel
                     • May need multiple returns to OR
                     • Critical for survival
                     • Plan at initial operation
                     1. ●

                        Action

                        Post-Operative Care

                        ICU management

                        • ICU monitoring
                        • Continue anticoagulation
                        • Nutritional support (TPN initially)
                        • Monitor for short bowel syndrome
                        • Address underlying cause (AF, hypercoagulable)
                        1. ✓

                           Outcome

                           Survival

                           Mortality 50-80% overall; early diagnosis critical

                        2. ✓

                           Outcome

                           Short Bowel Syndrome

                           If extensive resection - may need long-term TPN, intestinal rehabilitation

               2. ●

                  Action

                  Open SMA Embolectomy

                  First-line for arterial embolism

                  • Transverse arteriotomy at SMA
                  • Fogarty catheter embolectomy
                  • Intraoperative angiography
                  • Assess bowel viability after reperfusion
                  • Patch angioplasty if needed
               3. ●

                  Action

                  Endovascular Revascularization

                  Alternative for select patients

                  • Catheter-directed thrombolysis
                  • Mechanical thrombectomy
                  • Angioplasty ± stenting
                  • Best for thrombosis without necrosis
                  • May combine with laparoscopy for bowel assessment
               4. ●

                  Action

                  Mesenteric Bypass

                  For thrombosis with extensive disease

                  • Aorto-SMA bypass (antegrade)
                  • Iliac-SMA bypass (retrograde)
                  • Vein or prosthetic conduit
                  • Indicated for extensive atherosclerosis
                  • Higher complexity, longer procedure
            2. ●

               Action

               MVT Treatment

               Venous thrombosis - anticoagulation primary

               • Systemic anticoagulation (UFH then LMWH/warfarin/DOAC)
               • Duration: 6 months minimum, often indefinite
               • Surgery only if bowel necrosis
               • Hypercoagulable workup
               • Catheter-directed thrombolysis if progressing
            3. ●

               Action

               NOMI Treatment

               Non-occlusive mesenteric ischemia

               • Treat underlying cause (shock, CHF)
               • STOP vasoconstrictors if possible
               • Optimize cardiac output
               • Intra-arterial papaverine (30-60 mg/hr)
               • Surgery only if necrosis develops
      2. ●

         Action

         Immediate Anticoagulation

         UFH unless contraindicated

         • Unfractionated heparin IV
         • Prevents thrombus propagation
         • Continue until definitive treatment
         • Contraindications: active bleeding, recent surgery
      3. ●

         Action

         CT Angiography

         Gold standard - sensitivity/specificity >95%

         • Arterial + portal venous phase
         • SMA filling defect or occlusion
         • Bowel wall changes (edema, pneumatosis)
         • Portal venous gas (late, ominous)
         • Do NOT delay if clinical suspicion high