Treatment Medical Care No effective medical therapy exists. Percutaneous transluminal
angioplasty (PTA) may be an alternative therapy for selected patients.
Currently, the most common
indication for treatment of stenoses or
occlusions of mesenteric vessels is the presence of symptoms related to
intestinal ischemia. In the absence of sufficient data on the natural
history of mesenteric arterial stenosis, the presence of asymptomatic
disease does not constitute an indication for treatment. In the only
study reporting the clinical course of patients with asymptomatic
stenosis of mesenteric vessels, Thomas and colleagues reviewed 980
aortograms and identified 15 patients with stenosis of all 3 mesenteric
vessels, only 4 of whom developed symptoms.
4,5 Surgical Care Mesenteric
revascularization relieves the symptoms of abdominal angina
and may prevent intestinal infarction. Classically, the operation for
relieving the symptoms of abdominal angina includes thrombectomy
(removal of the obstructing lesion) and/or bypass of the obstructed
portion of the blood vessel with an endogenous or prosthetic vascular
conduit. Because
atherosclerosis involves systemic circulation,
generally all 3 blood vessels (celiac artery, superior mesenteric
artery, inferior mesenteric artery) are involved. Typically, patients
become symptomatic only when all 3 blood vessels are severely narrowed
by atherosclerosis. Relieving the symptoms of abdominal angina requires
revascularization of at least 2 of the 3 blood vessels. With the
advent of modern endovascular surgery, many new techniques have emerged
as possible alternatives to bypass surgery. Its less invasive nature
makes endovascular surgery ideal for patients with multiple
comorbidities, who may be at high risk for complications from open
surgery.When endovascular surgery for mesenteric revascularization is
performed, the patient is placed on a fluoroscopy table and sedated by
the anesthesiologist. Generally, most of these procedures do not
require general anesthesia. Bilateral groins are prepped and draped in
standard surgical fashion, the femoral pulse is palpated, and a needle
is inserted into the artery. Using the
Seldinger technique, a guide
wire is inserted through the needle, and its position is checked with
fluoroscopy. The artery is dilated, and sheaths are left in place. An
appropriate catheter is introduced through the sheath, and an angiogram
is performed.
6 Below is a more detailed description of endovascular surgery.
Endovascular surgery First, an aortogram is performed, and the origins of the celiac,
superior
mesenteric, and inferior mesenteric arteries are visualized.
The left anterior oblique view is best for visualizing the origins of
the celiac and superior mesenteric arteries. Once a narrowed artery is
identified, a guide wire is passed through the catheters, and an
attempt is made to pass the wire across the
narrowed portion of the
artery under direct fluoroscopy. Once the wire is passed across the
stenotic area, the artery's narrowed portion can be dilated with a
dilator, and a balloon angioplasty is performed.
If residual stenosis after the angioplasty is more than 50% of the expected artery luminal, it is advisable to place a stent
7 across
the narrowed portion of the blood vessel. After stent placement, an
angiogram is performed to determine whether there has been a complete
resolution of stenosis. If resolution has occurred, the catheters and
sheaths can be
removed. The arteriotomy site in the femoral arteries can
be closed by various commercially available endovascular devices or by
open surgical techniques. After the completion of the procedure,
patients are started on a clear liquid diet, with the diet advanced as
tolerated.
Potential complications of endovascular mesenteric revascularization
procedures are dissection of mesenteric arteries (which necessitates
conversion to
open surgery), rupture of mesenteric arteries (small
areas of perforation can be covered by stent grafts, but larger areas
of perforation require open surgery), embolization of atherosclerotic
plaques (which can lead to
gangrene of the small/large bowel), groin
hematoma (which necessitates performing duplex ultrasonography to rule
out pseudoaneurysm of the common femoral artery), and acute limb
ischemia (from embolization of atherosclerotic plaques to the
extremity).
Open surgeryLesions that are not amenable to endovascular management are dealt with
through open surgical technique. The surgery is performed under
general anesthesia, the patient’s abdomen is prepped and draped, and a
midline incision is made from xiphoid to pubic tubercle. Skin,
subcutaneous tissue, and anterior rectus fascia are divided, and the
peritoneal cavity is then entered. The transverse colon is reflected
upwards, and the middle colic artery is identified and traced back to
the origin of the superior mesenteric artery. Proximal and distal
control of the superior mesenteric artery is obtained and an
arteriotomy is performed to open the artery, followed by embolectomy
and removal of
atherosclerotic plaques.There are 2 types of arteriotomy that can be performed: transverse and
longitudinal. Transverse arteriotomy can be closed primarily, but for
longitudinal arteriotomies, a vein patch closure is preferred to avoid
residual stenosis of the artery. Other surgical options include the
following:
- Antegrade bypass: A vascular conduit is used to bypass the
stenosed area of the mesenteric vessel. Inflow is from the supraceliac
aorta. Unlike other vascular bypasses, where native vein is the
preferred conduit, prosthetic grafts are more suitable for mesenteric
revascularization. (See first 3 images below.)
- Retrograde bypass: In this bypass, inflow for the conduit comes
from the distal, nondiseased portion of the aorta or common iliac
arteries.