chronic mesenteric ischemia

Pathophysiology: Chronic mesenteric ischemia typically arises from severe atherosclerotic stenosis or occlusion of the mesenteric vasculature (celiac artery, superior mesenteric artery, inferior mesenteric artery). Because of extensive collateral circulation between these vessels, symptomatic disease usually requires significant stenosis of at least two of the three arteries. During digestion, splanchnic blood flow normally increases 2-3 fold to meet metabolic demands; in chronic mesenteric ischemia, stenotic vessels cannot accommodate this demand, leading to a mismatch between oxygen supply and demand, resulting in dull, crampy postprandial abdominal pain (intestinal angina) typically occurring 15-30 minutes after eating and lasting 1-2 hours.

Clinical features: The classic triad includes (1) postprandial abdominal pain, (2) significant weight loss due to food avoidance (sitophobia) as patients learn to avoid pain by eating less, and (3) abdominal bruit on auscultation due to turbulent flow through stenotic vessels. Pain is often periumbilical or epigastric. Patients frequently have other manifestations of systemic atherosclerosis (coronary artery disease, peripheral artery disease, cerebrovascular disease) and shared risk factors: smoking, diabetes, hypertension, hyperlipidemia, older age.

Diagnosis: CT angiography or duplex ultrasound is used to demonstrate stenosis/occlusion of mesenteric vessels. Catheter-based mesenteric angiography remains the gold standard, particularly for planning revascularization. Diagnosis requires correlating imaging findings of significant stenosis with clinical symptoms, as asymptomatic mesenteric artery stenosis is common in older adults due to collateral flow.

Treatment: Revascularization via endovascular angioplasty/stenting (preferred first-line, especially in higher-risk surgical patients) or open surgical bypass (particularly in younger, healthier patients or when endovascular approach fails). Risk factor modification (smoking cessation, statin therapy, antiplatelet therapy, blood pressure/glucose control) is essential given underlying systemic atherosclerosis.

Complications/Distinction from acute mesenteric ischemia: Chronic mesenteric ischemia can progress to acute mesenteric ischemia if a thrombus forms on a stenotic atherosclerotic plaque (acute-on-chronic ischemia), representing a surgical emergency with high mortality if not promptly treated. Unlike acute mesenteric ischemia (often embolic, presents with sudden severe pain out of proportion to exam), chronic mesenteric ischemia has an insidious onset with gradual postprandial symptoms.