Risk Factors for Hepatic Venous Outflow Obstruction in Piggyback Liver Transplantation: The Role of Recipient's Pattern of Hepatic Veins Drainage into the Inferior Vena Cava.

BACKGROUND The recipient's pattern of hepatic veins (HVs) drainage into the inferior vena cava (IVC) (drainage pattern, for short) may influence outflow reconstruction and thus hepatic venous outflow obstruction (HVOO) in piggyback liver transplantation (PBLT). However, no previous study has investigated this association. MATERIAL AND METHODS A retrospective analysis of 202 PBLT (2000-2016) was conducted. Based on drainage patterns, the patients were divided into Group A (common trunk of left and middle HVs), Group B (common trunk of right and middle HVs), and Group C (common trunk of 3 HVs). Patients' demographic and surgical data were compared within the 3 groups, and risk factors for HVOO were tested using a multiple logistic regression model. RESULTS A chi-square test revealed a significantly higher HVOO incidence in Group 1 compared with the other groups (23.5% vs. 9.6% vs. 7.1%, p=0.047). The demographics and surgical data except angleÐAOB between the reconstructed outflow and IVC in cross-section of 3D image (∠AOB), ratio of the length of reconstructed outflow and ∠AOB (LRO/∠AOB ratio), and types of HV ligation did not differ significantly within the 3 groups. ∠AOB and LRO/∠AOB ratio were used to assess the level of anastomosis twisting and compression, respectively. Among the 3 groups, the largest ∠AOB and highest LRO/∠AOB ratio were observed in Group A and B, respectively. In addition, multivariate analysis indicated that the ÐAOB (OR=1.016, 95%CI: 1.006-1.027) and LRO/ÐAOB ratio (OR=2.254, 95% CI: 1.041-5.519) were risk factors for HVOO. CONCLUSIONS This study demonstrated that drainage patterns were associated with HVOO. The best choice for outflow reconstruction is Group C. The patients in Group A and B were likely to develop HVOO due to anastomosis twisting and compression, respectively.