Diagnostic ultrasound ( PDFDrive )

CHAPTER 12 The Retroperitoneum 453
A
B
FIG. 12.25 Median Arcuate Ligament Syndrome. Male, 37 years old, with history of severe abdominal pain for more than 20 years.
(A) Duplex exam shows elevated velocity in the celiac artery of 361 cm/sec. (B) Computed tomography angiography sagittal reconstruction image
shows the characteristic narrowing of the celiac artery caused by the median arcuate ligament. Patient had immediate and enduring relief of
symptoms after surgery to release the median arcuate ligament.
must be impaired before the patient becomes symptomatic. In
most cases, two of the three arteries that supply mesenteric blood
low (celiac artery, SMA, IMA) must be severely diseased before
a patient experiences chronic mesenteric ischemia, but even many
patients with multiple-artery disease are not symptomatic. 108
Again, the clinician must remember that, although uncommon,
signiicant mesenteric ischemia can result from the narrowing
of one artery, particularly the SMA. 110
he onset of chronic ischemia is insidious, with the classic
patient experiencing weight loss and postprandial pain. Atypical
features in the history are common and oten include complaints
of “indigestion.” Patients with chronic ischemia frequently are
very thin, which facilitates ultrasound.
Vasculitis, most oten Takayasu arteritis, can also lead to
mesenteric ischemia. Although typically the symptoms are chronic,
involvement of the mesenteric arteries can be rapidly progressive
and result in bowel infarction. 111
Median Arcuate Ligament Syndrome
Most commonly, patients with symptomatic mesenteric ischemia
have at least two of the mesenteric arteries narrowed or completely
occluded. Patients with the median arcuate ligament syndrome
have narrowing only of the celiac artery.
he median arcuate ligament of the diaphragm is close to
the celiac artery. his ligament is a band of ibrous tissue that
crosses the aorta, usually above the origin of the celiac artery,
although the crossing can be below. Deformity and narrowing
of the celiac artery caused by the median arcuate ligament are
fairly common angiographic indings on lateral aortography. One
study reported that 24% of aortograms performed for unrelated
reasons showed celiac artery stenosis of at least 50% caused by
the median arcuate ligament. 112
In median arcuate ligament syndrome, patients with only
narrowing of the celiac artery experience signiicant postprandial
pain that results in avoidance of eating and weight loss. he
syndrome is poorly understood, but the pain is believed to be
possibly related to ischemia. 113,114 Other investigators support a
neurogenic cause. 115 Some patients respond dramatically to surgery
and become symptom free. 113-116 Surgical decision making in
these patients is very important to help decide those who are
likely to beneit from surgery. Surgery consists of dividing the
median arcuate ligament and may include celiac artery revascularization
(Fig. 12.25).
Mesenteric Artery Duplex Doppler Sonography
Mesenteric artery duplex Doppler ultrasound is most oten
performed with the patient fasting. Most studies assessing the
addition of a postprandial study conclude that it is not of
value. 117-119
Blood low to the intestines in the fasting state is relatively
low. Normal waveforms in the SMA and IMA are high resistance.
When the patient eats, blood is shunted to the intestines, and
the SMA has a lower-resistance waveform. he celiac artery
supplies the liver and spleen, which have a higher need for low
than the intestines when the patient is fasting. Accordingly, the
celiac artery has lower resistance than the SMA or IMA when
interrogated with the patient fasting.
Because chronic mesenteric ischemia can be fatal, it is critical
that the examination be performed and interpreted in a way that
guarantees very high sensitivity. he majority of stenoses that
result in chronic mesenteric ischemia are within the irst 1 to
2 cm of the origin of the celiac artery, SMA, and IMA. It is
possible, although rare, to have a branch artery occlusion that
results in chronic mesenteric ischemia. Ultrasound is not a reliable