KEY FACTS
Imaging
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Hepatic artery stenosis
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Elevated peak systolic velocity at anastomosis > 200-250 cm/s
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Parvus tardus waveforms in intrahepatic arteries
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Acceleration time > 0.08 s
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Resistive index < 0.5
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Hepatic artery thrombosis
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No detectable flow in hepatic artery with color or spectral Doppler
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May see “collateral transformation of hepatic artery”
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Tortuous collateral arteries in porta hepatis and parvus tardus intrahepatic arterial waveforms
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Pathology
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Hepatic artery stenosis
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Stenosis occurs at anastomosis
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Usually occurs at > 3 months post transplant
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Hepatic artery thrombosis
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May occur < 15 days or years after transplant
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Risk factors: Difference in hepatic artery caliber between donor and recipient, prolonged graft ischemia time, ABO blood group incompatibility, CMV infection, acute or chronic rejection, hypercoagulable state, sepsis
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Clinical Issues
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Hepatic artery stenosis
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May be related to injury at time of surgery or disruption of vasa vasorum with ischemia of hepatic artery
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Hepatic artery thrombosis
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Most common immediate vascular complication (2-12%)
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Complete occlusion of hepatic artery in early transplant period leads to liver failure
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Up to 75% of patients with hepatic artery thrombosis require retransplantation
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Biliary ducts in liver transplants supplied only by artery
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Hepatic artery thrombosis can result in biliary ischemia, bilomas, bile lakes
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Scanning Tips
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Due to patient body habitus, overlying gas or overlying surgical changes, HA may be difficult to visualize; different scanning positions (supine or LLD), different scanning windows (intercostal or subcostal), and different transducers (lower frequency transducer for large body habitus) may help
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If parvus tardus waveforms are seen, ensure that PW scale setting is not too high, which can mimic parvus tardus waveforms
