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Patients who have atherosclerosis affecting the arteries to their intestines can
present with acute or chronic symptoms. If there is a sudden closure of an artery
which supplies blood to a major portion of the intestine, patients can present with
extremely severe, acute, abdominal pain. The clinical situation is frequently one
in which a blood clot travels from the heart (in a patient with atrial fibrillation,
for example) and lodges in a major artery of the intestine. There is a group of
patients however, who have a chronic lack of circulation to the intestine. This
is called chronic mesenteric ischemia and their symptoms are sometimes referred
to as "mesenteric angina". This is caused by a gradual buildup of atherosclerotic
plaque in the arteries supplying the intestine. Patients typically complain of severe
abdominal pain, approximately one hour after eating. The increased demand for circulation
to the intestine, which occurs in response to eating a meal, cannot be met by the
arteries supplying blood to the intestine because those arteries are partially blocked.
This results in the typical mesenteric ischemic pain ("mesenteric angina"). Patients
typically will avoid eating because of the pain associated with having a meal. As
such, patients with chronic mesenteric ischemia typically have lost a significant
amount of weight before the diagnosis is ultimately determined. Many times, patients
with chronic mesenteric ischemia have undergone multiple tests before the diagnosis
is made. Not infrequently, patients will have undergone ultrasonography and CT scan
of the abdomen, colonoscopy and upper endoscopy before the diagnosis of mesenteric
ischemia is considered.
There are three major arteries supplying blood to the intestine. The celiac axis,
superior mesenteric artery, and inferior mesenteric artery. If only one artery is
heavily diseased, it is rare for a patient to have symptoms. When a patient has
symptoms of chronic mesenteric ischemia, they are typically found to have blockage
of at least two of the major arteries to the small and large intestine. If the diagnosis
is suspected, patients should usually undergo ultrasound evaluation in an attempt
to "image" the arteries to the intestine in a non-invasive manner. If it is suggested
by this test that there is a narrowing in the arteries, a conventional angiogram
may be recommended at that point. If a significant narrowing (greater than 75%)
is identified in the celiac axis and/or the superior mesenteric artery, treatment
options including balloon angioplasty and stenting of these arteries or bypass around
the blocked artery. After successful revascularization, patients usually will become
symptom free and begin to re-gain the weight lost during the time that the circulation
to the intestine was compromised.
Superior mesenteric artery (SMA) syndrome is a rare cause of abdominal pain and
duodenal obstruction caused by compression of the transverse duodenum between the
SMA and the aorta. It is usually thought that this condition occurs in individuals
who have had a severe, rather sudden, loss of weight. In patients with severe weight
loss, it is thought that the loss of retroperitoneal fat causes a change in the
individual's anatomy and this results in obstruction of the duodenum by compression
of this structure between the SMA and the Aorta. The diagnosis can be made by CT
scan using oral and intravenous contrast agents. Treatment depends on the cause.
Patients with severe weight loss may respond to nutritional support and weight gain.
Some patients may require surgical treatment.