Liver transplantation (LT) is not always feasible regarding the structures that needs to be reconstructed. Portal vein thrombosis (PVT) is one of the cause that can be a contraindicating factor [1,2]. Nevertheless, PVT is no longer considered as a contraindication even when thrombosis extended deep inside the superior mesenteric vein (SMV) [3]. Extra-anatomical reconstruction can be a solution for severe PVT, although the prognosis can be poorer compared to cases with successful anatomical reconstruction. In this article, we report two cases with successful LT in patients with Yerdel’s grade IV PVT without a visible systemic shunt using augmentation strategy combining the mesentseric flow with left renal vein (LRV) flow.

During the period of June 2021 to February 2022, two patients with Yerdel’s grade IV PVT without systemic shunt formation underwent living donor LT at Samsung Medical Center. The pre- and postoperative computed tomography (CT) were reconstructed three-dimensionally for the study. This study was approved by the institutional review board of Samsung Medical Center (IRB No. 2022-07-077).

Patient 1, Inflow Modulation Using Jumping Grafts from Superior Mesenteric Vein and LRV

A 59-year-old male patient who had a history of laparoscopic left hemihepatectomy for hepatocellular carcinoma experienced multiple intrahepatic recurrence and underwent systemic chemotherapy using atezolizumab and bevacizumab. Tumor progression developed and tumor thrombosis developed in the right portal vein and non-tumor thrombosis extended to the SMV. The patient underwent living donor LT.

Fig. 1A, B shows the initial finding of the patient. The PVT started from the intrahepatic portion of right portal vein extending to SMV reaching the first jejunal branch. Only minimal portal flow is maintained without visible systemic shunt formation. The three-dimensionally reconstructed view shows narrowed portal vein (PV) with PVT extending to the junction of SMV and splenic vein (Fig. 1C). During the operation, using both eversion technique through the portal opening and through the SMV using a venotomy incision failed to achieve sufficient flow and jump graft from the SMV was constructed using an iliac vein allograft. Even after inflow modulation using extra-anatomical flow from the SMV, the flow was considered insufficient and another jump graft from the LRV was constructed. The jump graft from the LRV was anastomosed in an end-to-side manner on the side wall of jump graft from the SMV. The augmented flow was anastomosed to the right portal vein of the graft and other surgical procedures were followed without serious complication. Both inflows from the SMV and LRV were patent until 6-month post-LT (Fig. 1D–F). After 6-month post-LT, intrahepatic recurrence was identified and the patient underwent transcatheter arterial chemoembolization for the intrahepatic recurrence and further maintained on sorafenib for distant metastasis.

Figure 1. Image findings of patients with severe PVT before and after transplantation who underwent living donor liver transplantation with portal flow augmentation combining jump graft from SMV and jump graft from LRV. (A, B) preoperative computed tomography and (C) three-dimensionally reconstructed view of PVT extending to the mesenteric-splenic junction. (D, E) postoperative computed tomography and (F) three-dimensionally reconstructed view of PVT extending deep inside the SMV. PVT, portal vein thrombosis; SMV, superior mesenteric vein; SV, splenic vein; LRV, left renal vein; PV, portal vein.

Patient 2, Inflow Modulation Using Main Portal Vein and Jumping Graft from LRV

A 55-year-old male experienced hepatocellular carcinoma with multiple recurrence throughout a 10-year period and underwent five sessions of radiofrequency ablation and three sessions of transcatheter arterial chemoembolization and radiotherapy. The patient gradually developed PVT which is mainly located on the portomesenteric junction which extended to the deep branches of the SMV. The patient did not develop systemic shunt and massive amount of ascites was identified.

Fig. 2A, B shows the initial findings of the recipient’s portal vein and SMV. As shown in Fig. 2B, C with the three-dimensionally reconstructed image, SMV thrombosis was formatted starting right under the junction with splenic vein. During the operation, portal flow was insufficient even after eversion thrombectomy. The surgical team decided to use the venous flow from the LRV. LRV was isolated and end-to-end anastomosis of LRV to iliac vein allograft was done and the other end was anastomosed in an end-to-side manner to the main portal vein. The portal flow was augmented and it was anastomosed to the graft’s portal vein. The patient recovered without serious complication and 3-month post-LT. CT revealed patent flow from both PV and LRV (Fig. 2D–F).

Figure 2. Image findings of patients with severe PVT before and after transplantation who underwent living donor liver transplantation with portal flow augmentation combining portal flow and jump graft from LRV. (A, B) preoperative computed tomography and (C) three-dimensionally reconstructed view of PVT extending to the mesenteric-splenic junction. (D, E) postoperative computed tomography and (F) three-dimensionally reconstructed view of PVT extending deep inside the SMV. PVT, portal vein thrombosis; SMV, superior mesenteric vein; SV, splenic vein; LRV, left renal vein; gPV, graft side portal vein; rPV, recipient side portal vein; PV, portal vein.

In most of the cases, PVT can be successfully removed surgically, and anatomical reconstruction can offer successful revascularization. However, when PVT lies deep inside extending to SMV, thrombectomy as well as revascularization is difficult. Extra-anatomical reconstruction can be a solution for these patients, while the outcome is inferior to anatomical reconstruction.

Normally, mesenteric outflow directly becomes the inflow through the portal vein. However, portal hypertension leading to systemic shunt formation can steal the mesenteric outflow to the systemic circulation reducing the amount of portal inflow. These situations can be corrected by directly ligating the shunt [4]. There are several studies reported for solving the problem of PVT in liver transplantation recipients. Most of the studies report good outcome with successful thrombectomy or using the collateral flow as the inflow to the liver [5-7].

However, there are situations when radiologically evident shunt formation is missing and portal recanalization ending up with poor blood flow. The two cases presented in this manuscript are cases that the surgical team were challenged by insufficient inflow with no other options to augment the portal inflow. While there was no spleno-renal shunt in both patients, venous outflow from the LRV was added to the portal inflow for augmenting the blood flow to the graft liver. Even though the outflow from LRV did not contain mesenteric blood flow, the amount added were sufficient for the liver graft. These rare but drastic cases which were solved by using blood flow from the LRV can be good guidance for surgeons facing similar situations during LT.

The limitation of this study is that it presented only two cases with very rare background. Another limitation is that we did not directly measure the portal flow but only the velocity. However, experienced surgical team can assess whether the portal inflow is sufficient for successful transplantation by visually observing the outflow from the portal vein. Therefore, objective measurement of portal flow is not essential during the process of LT.

In conclusion, by this study we presented that LT for patient with severe PVT within the SMV but without other systemic shunt formation can be successfully performed by augmenting the portal inflow using outflow from the LRV when thrombectomy fails to achieve sufficient flow.

This study was supported by Samsung Medical Center Grant #SMO1220681.

All authors have no conflicts of interest to declare.

Conceptualization: All. Data curation: All. Formal analysis: All. Methodology: All. Project administration: All. Resource: All. Software: All. Supervision: All. Validation: All. Visualization: All. Writing - original draft: All. Writing - review &editing: All.