What is the treatment for abdominal Superior Mesenteric Artery (SMA) issues?

Treatment of Superior Mesenteric Artery Disease

For acute SMA occlusion without peritonitis, endovascular therapy should be the first-line approach for revascularization, while patients with overt peritonitis require immediate laparotomy. 1

Acute SMA Occlusion Management

Initial Diagnostic Approach

• Obtain urgent CT angiography (CTA) with arterial and venous phases using 1mm slices to confirm diagnosis—this has 94% sensitivity and 95% specificity for acute SMA occlusion 1
• Consider D-dimer measurement (96% sensitivity) to help rule out acute mesenteric ischemia, though specificity is only 40% 1
• Elevated creatinine should NOT contraindicate CTA when clinical suspicion exists 1

Immediate Medical Management

• Initiate broad-spectrum antibiotics immediately due to high risk of bacterial translocation from mucosal barrier loss 1
• Start intravenous unfractionated heparin anticoagulation unless contraindicated 1, 2
• Aggressive fluid resuscitation while avoiding excessive crystalloid overload to optimize bowel perfusion 1, 2
• Use vasopressors cautiously only to prevent fluid overload and abdominal compartment syndrome 1

Treatment Algorithm Based on Clinical Presentation

If peritonitis present:

• Proceed directly to emergency laparotomy without delay—bowel infarction has already occurred and mortality exceeds 50% 1, 2
• Perform midline laparotomy with assessment of all intestinal segments 1
• Goals include: (1) re-establishing blood supply, (2) resecting non-viable bowel, (3) preserving all viable bowel 1

If NO peritonitis present:

For acute thrombotic occlusion:

• Endovascular therapy is first-line for mesenteric revascularization (Class IIa recommendation) 1
• Endovascular treatment shows lower mortality (25%) compared to open surgery (40%) 1
• Techniques include balloon angioplasty with or without stenting 1, 3

For acute embolic occlusion:

• Both endovascular and open surgical therapy should be considered (Class IIa recommendation) 1
• Embolectomy and angioplasty are well-established definitive treatments 1
• Approximately 20-30% can survive with bowel resection alone, especially with distal embolism 1

Revascularization Timing

• Attempt revascularization FIRST unless serious peritonitis and septic shock are present 1
• Most patients with acute SMA occlusion require immediate revascularization to survive 1
• Revascularization reduces 30-day mortality from 62% (without revascularization) to 42% (with revascularization) 1

Surgical Revascularization Techniques

• Embolectomy for embolic disease via direct SMA exposure at the root of mesentery 1
• Bypass procedures for thrombotic disease at aortic origin—can be antegrade (from supraceliac aorta) or retrograde (from infrarenal aorta/iliac arteries) 1
• Single-vessel SMA revascularization is usually sufficient in acute settings 1
• Consider temporary SMA shunting for patients in extremis or when technical expertise unavailable 1

Contraindications to Endovascular/Thrombolytic Therapy

• Any evidence of bowel ischemia or infarction precludes thrombolytic therapy 1
• Recent surgery, trauma, cerebrovascular or GI bleeding, uncontrolled hypertension 1
• Clinical or imaging evidence of advanced bowel ischemia 1

Second-Look Strategy

• Plan for second-look laparotomy at 24-48 hours when bowel viability is uncertain 1
• Use temporary abdominal closure with negative pressure wound therapy 1
• Document bowel length clearly in every operative note 1

Chronic Mesenteric Ischemia (CMI)

Clinical Recognition

• Classic triad: postprandial abdominal pain, weight loss, food aversion (appetite preserved unlike malignancy) 1
• May also present with diarrhea or constipation 1

Treatment Approach

• Do NOT delay revascularization to improve nutritional status—delayed treatment associated with clinical deterioration, bowel infarction, and sepsis 1
• No indication for prophylactic revascularization in asymptomatic disease 1
• Endovascular therapy with angioplasty and stent placement is now first-line treatment over open surgery due to lower perioperative morbidity 2, 4
• Technical success rates of 85-100% with stent placement 2
• Prioritize SMA treatment over celiac artery 2

Non-Occlusive Mesenteric Ischemia (NOMI)

• Treat the underlying precipitating cause (low cardiac output, shock) rather than attempting revascularization 2
• Optimize cardiac output and fluid resuscitation 2
• Consider catheter-directed vasodilator therapy 2, 4
• Full-dose anticoagulation should be initiated 1

Follow-Up and Surveillance

• Lifelong anticoagulation/antiplatelet therapy required after acute mesenteric ischemia treatment 2
• Surveillance with CTA or duplex ultrasound at 6 months, then at 1,6, and 12 months, then annually 2