Transaortic Splanchnic Endarterectomy for Chronic Mesenteric Ischemia

Diagnosis and Evaluation of Chronic Mesenteric Ischemia

The syndrome of chronic mesenteric ischemia was first recognized clinically by Dunphy in 1936, who reviewed the autopsy results of patients dying of gut infarction and documented that most patients had a prodrome of abdominal pain and weight loss before development of gut infarction. Recognition of this clinical syndrome suggested the potential for identifying patients before gut infarction, which would be a critical observation because attempts at splanchnic revascularization for acute mesenteric ischemia continue to be accompanied by operative mortality rates as high as 60%, with increased rates of major complications. Progression of mesenteric stenosis to occlusion is thought to account for 20% to 50% of cases of acute mesenteric ischemia.

Because chronic mesenteric ischemia is uncommon, a long delay often occurs between the onset of symptoms and clinical recognition of this syndrome. It is often diagnosed only after all alternative diagnoses have been excluded. Unlike extremity arterial occlusive disease or carotid artery occlusive disease, symptomatic mesenteric artery occlusive disease is seen more commonly in women than in men. Virtually every patient who presents with mesenteric ischemia continues to smoke and has manifestations of advanced systemic atherosclerosis despite a relatively young age (6th or 7th decade).

Approximately 90% of patients present with postprandial pain. Most typically, these patients describe epigastric postprandial pain that usually occurs within 15 to 30 minutes after eating a meal. Diarrhea or other manifestations of malabsorption are distinctly uncommon. The severity and chronicity of the postprandial pain often lead to a fear of eating and subsequent weight loss. Weight loss has occurred in 70% of patients in modern series.

Once the diagnosis of chronic mesenteric ischemia is suspected in a particular patient, an extensive evaluation is begun to exclude alternative diagnoses, most commonly a gastrointestinal malignancy. A not uncommon feature of chronic mesenteric ischemia is the development of gastric ulcers, which are often multiple small ulcers of irregular shapes with whitish sclerotic bases located in the antrum. These ulcers often fail to heal with conservative therapy and are themselves a manifestation of ischemia. Delays in treatment often result from either attributing the patient’s symptoms to these ulcers or attempting to persist with medical therapy beyond a reasonable period of time. It is important to recognize that these ulcers will heal rapidly after intestinal revascularization.

In the absence of a pathognomonic test for chronic mesenteric ischemia, most patients undergo extensive endoscopy and computed tomography (CT) examination of the abdominal cavity. Once the clinical syndrome of postprandial pain and weight loss is recognized, and other diseases have been excluded, the patient should undergo noninvasive imaging. In adept hands, visceral duplex accurately identifies the presence of hemodynamically significant CA and SMA stenosis or occlusions. Positive or equivocal results when chronic mesenteric ischemia is suspected necessitate further imaging in order to plan revascularization.

The subsequent test of choice is CT angiography (CTA) because it provides excellent delineation of the severity and length of occlusive lesions, associated aortic disease, and angulation of the origins of the mesenteric vessels relative to the aorta. This is valuable information for planning open and endovascular approaches to revascularization. Digital subtraction angiography with lateral aortography then defines the origins of the celiac artery and SMA, and if an endovascular revascularization is deemed preferable, it can be carried out at the same time. If an open revascularization is chosen, subtraction angiography provides the most reliable evaluation of the extent of disease to plan this reconstruction. More than 90% of patients with chronic mesenteric ischemia have severe stenosis or occlusions of the CA and SMA, as well as the inferior mesenteric artery (IMA).