A whole left liver (LL) graft has been used for liver transplantation in pediatric patients older than infants. The middle hepatic vein (MHV) can be included at the left liver graft. However, deprivation of MHV outflow drainage can result in significant hepatic venous congestion at the remnant right liver [1-3]. To prevent such detrimental hepatic venous congestion (HVC), we have reported surgical techniques for MHV-preserving LL graft [4]. However, such techniques usually result in excessively enlarged opening of the graft outflow vein, which is too large for most pediatric recipients. Complete preservation of the donor MHV trunk can make some branches of the MHV exposed at the cut surface of the LL graft. In such situations, a customized funneling venoplasty technique is necessary to make it suitable for LL graft outflow vein reconstruction for a pediatric recipient with a relatively small inferior vena cava (IVC) [4,5]. This technique is a counterpart of modified right liver graft with reconstruction of MHV branches [6]. We herein present a case of funneling venoplasty of MHV branch-preserving LL graft in a pediatric patient undergoing living donor liver transplantation (LDLT).

The recipient was a 31-month-old girl who was diagnosed with biliary atresia. The patient underwent Kasai portoenterostomy at 1 month after birth. Liver function of the patient deteriorated progressively (Fig. 1). Thus, we decided to perform LDLT at a body weight of 15 kg because of a low pediatric end-stage liver disease score in the situation of marked shortage of deceased donors.

Figure 1. Perioperative computed tomography finding of the donor. (A–C) The anatomy of the middle hepatic vein has large segment VIII (V8) and segment V veins with a fissural vein. (D) Hepatic parenchymal transection line indicates the cutting lines of the middle hepatic vein branches. (E, F) V8 vein is preserved with minimal development of hepatic venous congestion.

The donor was the 41-year-old mother of the patient. Computed tomography (CT) volumetric volumes of the left lateral section and LL were 250 mL and 407 mL, respectively, which were estimated to be graft-to-recipient weight ratios (GRWRs) of 1.67% and 2.71%, respectively. We decided to use the LL of the donor. The anatomy of the MHV had large segment VIII (V8) and segment V (V5) veins at the right liver with separate ventral segment IVa (V4a) and dorsal segment IVb (V4b: fissural vein). Transection at the level of the MHV trunk would make two separate large graft hepatic veins, which might induce huge HVC at the right liver and require direct unification venoplasty. To protect the donor’s remnant liver from excessive HVC, we decided to preserve the large V8 branch at the donor remnant liver (Fig. 2).

Figure 2. Pretransplant computed tomography finding of the recipient. (A) Liver cirrhosis with biloma is identified. (B) The portal vein appears normal with collateral formation.

A V8-preserving whole LL graft was harvested, with a graft weight of 320 g at the back table, equivalent to a GRWR of 2.13%. There were three separate outflow veins at the graft liver cut surface. We adopted the technique of MHV branch reconstruction developed for a modified right liver graft. A 10-cm-long cold-preserved iliac vein graft was prepared at the institutional tissue bank. The internal semilunar valves at the common iliac vein level were excised. Because the wall of the femoral vein stump appeared thicker, this stump was unified with the graft left hepatic vein orifice through central septotomy and running sutures. The V4b orifice was anastomosed with the vein conduit in an end-to-side fashion. The V5+V4a orifice was also anastomosed with the vein conduit in an end-to-side fashion. The distal end of the vein conduit was tightly ligated. A leak test using a sphoid was performed to check the security of anastomoses. The conjoined outflow orifice appeared to be rather small, thus an incision was made at the left lateral wall of the graft left hepatic vein (LHV). These procedures resulted in a single outflow vein orifice of 3 cm in the transverse diameter (Fig. 3).

Figure 3. Bench work for graft outflow vein reconstruction. (A) There are three separate outflow veins at the graft liver cut surface. (B) A 10-cm-long cold-preserved iliac vein graft was prepared. (C, D) The stump of the vein graft is unified with the graft left hepatic vein orifice through central septotomy and running sutures. (E) The fissural vein orifice was anastomosed with the vein conduit in an end-to-side fashion. (F) Segment V and segment IVa vein orifices are anastomosed with the vein conduit in an end-to-side fashion. (G) The distal end of the vein conduit is tightly ligated and a leak test is performed. (H) The conjoined outflow orifice is widened by making an incision at the left lateral wall of the graft left hepatic vein.

Because there was no anatomical variation in the recipient, standard procedures of pediatric LDLT were performed. After dissecting the recipient’s native liver was completed, the hepatic parenchyma was incised with a surgical knife, leaving a bulk of hepatic parenchyma around the hepatic vein trunks. The hepatic parenchyma was forcefully pulled out to detach it from the hepatic vein stumps, which made stump walls long and thick. No venoplasty was applied to the recipient’s IVC orifice. The interposed funnel-shaped orifice of the graft hepatic vein was anastomosed with the recipient’s IVC orifice by 1:1 size matching (Fig. 4). The recipient’s portal vein was normal-looking, thus it was anastomosed with the graft portal vein stump using a branch patch. Coronary collateral veins were ligated at the level of the less curvature of the stomach. The graft hepatic artery was reconstructed under surgical microscopy. Finally, Roux-en-Y hepaticojejunostomy was performed.

Figure 4. Intraoperative photographs of graft hepatic vein reconstruction. (A) The recipient hepatic vein orifices are widely opened without venoplasty. (B, C) The conjoined orifice of the graft hepatic vein is anastomosed with the recipient inferior vena cava orifice by 1:1 size matching. (D) The interposed vein graft is bulged after portal reperfusion.

The pathology report of the explant liver revealed cirrhosis of macronodular and micronodular type, with marked loss of intrahepatic bile ducts. These findings were consistent with end-stage biliary atresia (Fig. 5). Early follow-up CT scan of the recipient showed no vascular complications with patient graft outflow veins (Fig. 6). The patient recovered uneventfully from the LDLT operation. She has been doing well for three months after transplantation. The donor also recovered uneventfully, showing no evidence of HVC at CT follow-up (Fig. 2).

Figure 5. Gross photograph of the explant liver.

Figure 6. Follow-up computed tomography images taken 4 days after liver transplantation. (A–C) The hepatic vein reconstruction appears smooth and streamlined without stenosis. (D) The portal vein reconstruction shows no stenosis.

A conventional LL graft usually means inclusion of the MHV trunk at the graft liver side. However, deprivation of MHV outflow drainage can result in HVC at the remnant right liver [1-3]. To prevent such detrimental HVC, we have reported surgical techniques for V8-preserving LL graft. Our previous study on MHV anatomy revealed thar only 12 (8.2%) of 147 (8.2%) LL graft donor livers were indicated for tailored V8 preservation [4]. The anatomical conditions to determine the feasibility of tailoring V8 preservation included direct convergence of V8 on the MHV trunk, absence of multiple MHV-LHV branching at the graft cutting line, and HVC-prone MHV anatomy [4]. Our current donor did not meet these conditions, thus tailored V8 preservation was not indicated.

Instead of performing tailored V8 preservation without requiring a vein patch, we selected vein interposition at the expense of V8 preservation. This technique is a counterpart of modified right liver graft with reconstruction of the MHV branches [6]. Because pediatric recipients have smaller inferior vena cava than adult recipients, a customized funneling venoplasty technique is necessary to make the graft outflow vein orifice small. We previously presented a similar technique in a LDLT case using a left lateral section graft with type 4 LHV, which was a customized interposition-wedged unification venoplasty using an ilio-femoral vein homograft [1].

In the present case, HVC at the donor remnant right liver was prevented effectively. However, if suitable vessel homograft is not available, the MHV trunk could be transected to make single LL graft outflow vein without patch venoplasty. We have previously analyzed postoperative courses of 27 LL graft donor livers to understand resolution processes of HVC [4]. Significant communication between MHV and right hepatic vein was detected in 2 (7.4%) donor livers. We hardly identified it prospectively on preoperative CT, but it was easily identified retrospectively after comparison with the postoperative CT scan. We identified a unique phenomenon of V8 flow reversal after MHV clamping when there was a significant intervenous collateral vein. We think that prompt reversal of V8 flow might be beneficially associated with pre-existence or early formation of venous collaterals. In contrast, loss of V8 flow after its clamping implicates poor or delayed postoperative resolution of HVC. Another 10 donor livers have revealed definite enhancement of V8 in 1-week CT scans, which might imply timely occurrence of collaterals. However, such V8 enhancement was not detected in the other 15 donor livers. Absence of V8 enhancement was related to extensive occurrence of CT hypoattenuation [4]. Considering long-term morphological changes at the HVC area, we strongly suggest extensive HVC should be avoided if possible.

As abovementioned, our current technique is a counterpart of modified right liver graft with reconstruction of the MHV branches [6]. This type of liver graft can be called a modified left liver graft, as it is a part of graft standardization for LDLT [7]. Any MHV branches exposed at the LL graft cut surface can be reconstructed with an interposed vein graft. Although prosthetic vascular grafts can be used for adult recipients, they cannot be used for pediatric recipients. Thus, availability of sizable vein homograft is the prerequisite for MHV reconstruction.

In conclusion, our surgical technique using funneling venoplasty enabled successful reconstruction of MHV branches at the LL graft. Our experience suggests that individualized reconstruction techniques should be applied for pediatric patients undergoing LDLT using an LL graft with variant MHV anatomy.

There was no funding related to this study.

All authors have no conflicts of interest to declare.

Conceptualization: JMN, GCP, SH. Data curation: All. Methodology: All. Resources: KMK, SHO. Supervision: SH. Visualization: SH. Writing - original draft: JMN, GCP, SH, SHK, S Ha. Writing - review &editing: JMN, GCP, SH.