Compromised splanchnic blood flow — acute (embolic/thrombotic/NOMI/venous) is rapidly fatal; chronic causes 'intestinal angina.'
Also known as: acute mesenteric ischemia, AMI, chronic mesenteric ischemia, intestinal angina, NOMI, mesenteric venous thrombosis
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Risk factors
- Embolic AMI: atrial fibrillation, recent MI with mural thrombus, infective endocarditis, atrial myxoma, valve disease
- Thrombotic AMI: pre-existing atherosclerosis with chronic mesenteric ischemia, hypercoagulable states
- NOMI: severe hypotension, cardiogenic shock, vasopressor use, cocaine/digitalis, dialysis
- Mesenteric venous thrombosis: hypercoagulable disorders (factor V Leiden, JAK2, antiphospholipid syndrome, malignancy), portal hypertension, recent abdominal surgery, OCPs, intra-abdominal infection
- CMI: tobacco use, female sex, age >60, diffuse atherosclerosis (concurrent CAD, PAD, CVD)
Pathophysiology
The intestinal mucosa is highly sensitive to ischemia; within 1-3 hours of arterial occlusion mucosal sloughing occurs, and full-thickness necrosis follows within 6-12 hours. Reperfusion produces oxidative injury and bacterial translocation, leading to systemic inflammatory response and multiorgan failure. In CMI, postprandial demand exceeds chronically reduced supply, causing 'intestinal angina' and food fear.
Clinical presentation
Symptoms
- AMI: sudden, severe abdominal pain out of proportion to physical findings; nausea, vomiting, urgent diarrhea; later, distention and bloody stools as bowel infarcts
- Mesenteric venous thrombosis: more subacute (days to weeks) of abdominal pain, anorexia, nausea
- CMI: postprandial abdominal pain (intestinal angina) 15-60 min after meals, weight loss, food fear (sitophobia), diarrhea
Signs / physical exam
- AMI early: minimal exam findings despite severe pain — the cardinal clue
- AMI late: peritoneal signs, hypotension, fever, acidosis, altered mentation
- CMI: thin appearance, weight loss, abdominal bruit (~50%), evidence of generalized atherosclerosis
- Atrial fibrillation in embolic AMI
Classic findings
Pain out of proportion to exam in an older patient with atrial fibrillation is acute embolic mesenteric ischemia until proven otherwise.
Differential diagnosis
- Small bowel obstruction — Dilated bowel with transition point on CT; vomiting, no out-of-proportion pain initially
- Acute pancreatitis — Elevated lipase, characteristic CT findings; pain radiates to back
- Perforated viscus — Free air on CXR/CT, peritonitis, sudden severe pain
- Ruptured AAA — Pulsatile mass, hemodynamic instability, retroperitoneal hematoma on CT
- Diverticulitis — LLQ pain, fever, focal inflammation on CT
- Ischemic colitis (left colon, watershed) — Hematochezia, milder pain, often older patients with hypotension; usually self-limited
- Gastric/duodenal ulcer — Epigastric pain, may be relieved or exacerbated by food; EGD
- Peptic ulcer disease / dyspepsia (vs CMI) — No weight loss or food fear; EGD diagnostic
Diagnostic workup
Diagnostic criteria
CTA demonstration of SMA/IMA/celiac occlusion, venous thrombosis, or hypoperfusion with characteristic bowel wall findings; CMI requires ≥2 vessel involvement on imaging plus appropriate clinical syndrome.
Labs
- CBC (leukocytosis), BMP, lactate (elevated late, but normal lactate does not rule out AMI early), LDH, amylase/lipase, LFTs
- ABG (metabolic acidosis), coagulation studies
- Hypercoagulable workup if venous thrombosis suspected
Imaging
- CT angiography (CTA) of abdomen — gold standard initial test; identifies arterial occlusion, venous thrombosis, bowel wall thickening, pneumatosis, portal venous gas
- Mesenteric duplex ultrasound — screening for CMI
- Conventional mesenteric angiography — therapeutic (catheter-directed thrombolysis, stent placement) and confirmatory
- Plain abdominal radiograph — nonspecific; late findings include thumbprinting and pneumatosis
Complications
- Bowel infarction and necrosis
- Short bowel syndrome after extensive resection
- Sepsis, multiorgan failure
- Recurrent ischemia, restenosis after revascularization
- Chronic malnutrition (CMI)
- Postoperative anastomotic leak, prolonged ICU course
PANCE pearls
- Pain out of proportion to exam = mesenteric ischemia until proven otherwise.
- Normal lactate does NOT rule out early AMI — clinical suspicion drives early CTA.
- Embolic AMI in a-fib classically lodges 3-10 cm distal to the SMA origin, sparing the proximal jejunum and right colon.
- Mesenteric venous thrombosis is more subacute and is the variant in younger patients with hypercoagulable disorders.
- Triad of postprandial abdominal pain + weight loss + food fear in an older smoker = chronic mesenteric ischemia.
References
- WSES 2017 — World Society of Emergency Surgery guidelines for the diagnosis and management of acute mesenteric ischemia (Bala et al., World J Emerg Surg 2017)
- ESVS 2017 — European Society for Vascular Surgery clinical practice guidelines on the management of mesenteric arterial diseases
- SVS 2020 — Society for Vascular Surgery clinical practice guidelines for mesenteric ischemia
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