Diagnostic ultrasound ( PDFDrive )

CHAPTER 18 Organ Transplantation 637
A
B
C
FIG. 18.14 Celiac Artery Stenosis: Impingement by Median
Arcuate Ligament. (A) Transverse sonogram shows narrowing of the
celiac artery secondary to impingement by the median arcuate ligament
(arrow). (B) Spectral trace of the region of narrowing shows elevated
peak systolic velocities of 412 cm/sec. (C) Spectral trace of left lobe
intrahepatic arterial branch shows low-resistance tardus-parvus waveform.
After surgical ligation of the median arcuate ligament, the spectral
waveforms returned to normal.
collections. 26,40 Gray-scale ultrasound shows echogenic thrombus
within the IVC that may continue into the hepatic veins. In cases
of recurrent HCC, tumor thrombus may extend from the hepatic
veins into the IVC (Fig. 18.20).
Hepatic Vein Stenosis
Hepatic vein stenosis occurs with a frequency of 1% in orthotopic
liver transplant and 2% to 5% in living donor transplants. his
discrepancy in frequency is primarily related to diferent surgical
techniques. In orthotopic liver transplants, an anastomosis is
performed between the donor and recipient IVC without touching
the hepatic veins. In living donor transplants, however, the donor
hepatic vein is anastomosed to either the hepatic vein stump or
the IVC of the recipient. his results in the hepatic veins being
rigidly ixed in position, such that any movement of the grat
produces a buckling and narrowing of the hepatic veins. In
addition, progressive growth of partial liver grats ater surgery
may result in stretching or twisting of the hepatic veins, further
contributing to narrowing of the venous outlet. 41,42
Clinically, hepatic vein stenosis manifests with liver congestion,
hepatomegaly, ascites, and/or pleural efusions. Hepatic
venous obstruction in the early postoperative state is a surgical
emergency, and reoperation is usually necessary for correction
or for retransplantation, if substantial hepatic necrosis has
occurred. Late-onset hepatic venous obstruction may be
associated with a more insidious deterioration in liver function.
hese patients may beneit from metallic stent insertion
or balloon venoplasty, because surgical correction is oten
diicult as a result of ibrotic changes around the anastomotic
sites. 41,42
Direct signs of hepatic vein stenosis include focal narrowing
on gray-scale ultrasound associated with turbulent low on color
and spectral Doppler interrogation (Fig. 18.21). A persistent,
monophasic spectral waveform is suggestive of, but not diagnostic
of, hepatic vein stenosis; monophasic waveforms may also be
present in normal, nonobstructed hepatic veins. However, the
presence of a triphasic or biphasic waveform rules out clinically
important hepatic vein stenosis. 42