Mesenteric Artery Stenosis

What is it?

The mesenteric arteries are the blood vessels that supply blood to the intestines and other digestive organs in the abdomen. The three main arteries are the celiac trunk (which supplies the stomach, liver, spleen, pancreas, and the first part of the small intestine), the superior mesenteric artery (SMA, which supplies most of the small intestine and the first part of the large intestine), and the inferior mesenteric artery (IMA, which supplies the rest of the colon and the upper rectum). These arteries are interconnected by a network of smaller vessels (collateral circulation) that can compensate when one of the main arteries becomes narrowed. Mesenteric artery stenosis is a narrowing of one or more of these vessels.

The most common cause is atherosclerosis—plaque buildup in the artery walls similar to that which causes coronary and peripheral arterial disease. Atherosclerotic mesenteric artery stenosis most often involves the origins of the celiac trunk and SMA, where they branch from the aorta. Less common causes include median arcuate ligament syndrome (in which a fibrous band from the diaphragm compresses the celiac trunk), fibromuscular dysplasia, vasculitis (such as polyarteritis nodosa or Takayasu arteritis), prior radiation, dissection, and rare congenital or genetic conditions. Acute mesenteric ischemia can also result from blood clots that form in the arteries (thrombosis), clots traveling from elsewhere (embolism—often from the heart in patients with atrial fibrillation), or significantly reduced blood flow (non-occlusive ischemia) in critically ill patients.

The clinical importance of mesenteric artery stenosis depends on which arteries are affected, how severe the narrowing is, and how well the collateral circulation can compensate. Many people with imaging-detected stenosis of one mesenteric artery have no symptoms because the other arteries and collateral vessels maintain adequate blood flow to the intestines. Chronic mesenteric ischemia—the symptomatic form of chronic mesenteric stenosis—typically occurs only when two or more of the three main mesenteric arteries are significantly narrowed, although exceptions exist. Acute mesenteric ischemia can occur even when only one main artery is suddenly blocked, particularly the SMA.

Symptoms of chronic mesenteric ischemia classically include abdominal pain that begins shortly after eating (often called “intestinal angina”), unintentional weight loss, and “food fear” in which patients avoid eating to prevent pain. Other possible symptoms include nausea, vomiting, diarrhea or other change in bowel habits, and feelings of bloating. Symptoms often develop gradually over months to years and may be misattributed to other gastrointestinal conditions. Patients with median arcuate ligament syndrome may have more variable symptoms, sometimes triggered by position or exertion.

Acute mesenteric ischemia presents very differently. Patients typically develop sudden, severe abdominal pain that may seem out of proportion to physical examination findings, often accompanied by nausea, vomiting, urgent bowel movements, and—as the condition progresses—signs of shock, sepsis, and bowel injury. Acute mesenteric ischemia is a surgical emergency with high mortality if not recognized and treated promptly.

CT angiography of the abdomen and pelvis is the primary imaging test for evaluating suspected mesenteric artery disease, both acute and chronic. It provides detailed images of the aorta and its branches, identifies stenoses, assesses for thrombus or embolus, and evaluates the bowel for signs of ischemia. MR angiography is an alternative when avoiding radiation or iodinated contrast is preferred. Doppler ultrasound of the mesenteric arteries provides functional information about flow velocities, although it can be limited by body habitus and bowel gas. Invasive catheter-based angiography is reserved for selected patients, typically at the time of planned intervention.