The Significance of Hepatic Vein Outflow Volume in Hepatic Outflow Insufficiency of Living Right Liver Graft Evaluated by Doppler Ultrasound

Hemodynamics-compliant reconstruction of the right hepatic vein for adult living donor liver transplantation with a right liver graft

Secure reconstruction of the right hepatic vein (RHV) is essential for the successful implantation of a right liver graft during living donor liver transplantation (LDLT). To develop reliable surgical techniques for RHV reconstruction, we performed 3 concurrent studies: a simulation study using a fluid dynamics experimental model and a computational simulation model; an observational study analyzing the hemodynamic changes during radiological interventions for RHV stenosis; and a prospective clinical study establishing hemodynamics-compliant surgical techniques. The simplified fluid dynamics experimental model revealed that actually measured outflow volumes were very similar to theoretical values derived from a fluid dynamics formula. The computational simulation model showed that outflow decreases were nearly linearly correlated with the degree of stenosis when it exceeded 50%. The clinical observational study revealed that mild (≤50%), moderate (50%-75%), and severe RHV stenoses (≥75%) had mean pressure gradients of 2.5 ± 1.0, 6.6 ± 2.3, and 9.6 ± 2.8 mm Hg, respectively. The prospective clinical study was performed for patients who underwent RHV reconstruction with RHV angle blunting and inferior vena cava enlargement (n = 274); a historical control group of patients who underwent reconstruction by other methods (n = 225) was also used. RHV stenting within 2 weeks and 1 year was necessary for 1 patient (0.4%) and 5 patients (1.8%) in the study group, respectively, and for 9 patients (4.0%) and 21 patients (9.1%) in the control group, respectively (P < 0.01). The mean cephalocaudal length of patulous RHV anastomoses was greater in the study group versus the control group (P < 0.001). In conclusion, our modified RHV reconstruction technique significantly reduces the risk of RHV stenosis. We thus suggest the routine or selective use of this technique as a part of graft standardization for LDLT using a right liver graft.

Value of CT and Doppler Sonography in the Evaluation of Hepatic Vein Stenosis After Dual-Graft Living Donor Liver Transplantation

OBJECTIVE

The purpose of this study was to evaluate the imaging findings and role of CT and Doppler sonography in the diagnosis of hepatic vein (HV) stenosis after dual-graft living donor liver transplantation (LDLT).

MATERIALS AND METHODS

Using hepatic venography as the reference standard, 73 grafts with venographic evaluation in 43 dual-graft LDLT recipients were classified into either a stenosis (n = 39) or a nonstenosis (n = 34) group. CT scans were evaluated for relative attenuation, enhancement pattern, and HV abnormality for each graft. Doppler sonography evaluation of the flow pattern of HVs for each graft was performed. CT and Doppler sonography findings were compared in the stenosis and nonstenosis groups using the independent sample Student's t test and Fisher's exact test. Multifactorial logistic regression analysis was performed to determine the best predictors of the diagnosis of HV stenosis.

RESULTS

Heterogeneous enhancement (p = 0.046), abnormal HV on CT (p = 0.025), and HV wave pattern on Doppler sonography (p = 0.005) were significant findings. The accuracy for the diagnosis of HV stenosis was 60.0% for heterogeneous enhancement, 61.5% for abnormal HV, and 66.2% for a monophasic flow pattern. Heterogeneous enhancement and HV wave pattern were significant independent findings on multifactorial logistic regression analysis. The overall accuracy of the logistic model in the diagnosis of HV stenosis was 71.7%.

CONCLUSION

Although CT and Doppler sonography can be helpful in diagnosing HV stenosis, given the low accuracy of individual imaging findings, the diagnosis of HV stenosis should be made cautiously, with both CT and Doppler sonography regarded as complementary examinations.