Left Liver With Right Paramedian Sector—Can It Be An Option in Living Donor Liver Transplantation?

Abstract

We read with interest the article titled “The changes of the medial right lobe, transplanted with left lobe liver graft from living donors” by Ikegami et al. (1). This type of graft was reported previously by the same group (2), and the clinical results of living donor liver transplantation using the grafts were described in detail in Ref. 1. The authors suggest that procurement of a left lobe living donor graft with the medial part of the right lobe (mRL), a full left liver with the medial part of the anterior ventral segment according to Couinaud’s portal segmentation, is an innovative technique in living donor liver transplantation. In all cases, the mRL volume had increased after transplantation. However, we have some difficulties accepting the authors’ conclusion that the volume of the mRL increased in the recipients as we responded to their previous work (3). The blood supply to the mRL still remains as a matter for speculation. They suggested lobar communication through sinusoidal perfusion as one of the potential reasons for regeneration of the mRL. However, clinical experience has taught us that a lack of portal inflow as a result of tumor growth or surgical maneuvers results in atrophy of the region and that the role of sinusoidal perfusion is limited (4). They described the area whose surface was not discolored by right or left Glissonean pedicle (Fig. 4C and D). This phenomenon was suggested to be caused by lobar communication through sinusoidal perfusion. However, the possibility could not be excluded that the no discoloration area was provided just by communicating arcades between the right and left small-hepatic arteries close to the hilar bile duct (5). The method of volumetry in the postoperative computed tomography (CT) scans must be carefully evaluated. It is difficult to understand how they determined the dotted line in Figure 3(B), which was drawn to discriminate the mRL from the left liver. The right side of the dotted line (their mRL) seems to include the portal branch of the left portal vein. The territory of the portal branch coming from the left portal vein should be defined as the left liver. A volume evaluation with a region-growing software (Hitachi Image Processing System, Hitachi Medical Corporation, Japan) in the postoperative CT (6) will provide a more accurate volume evaluation similar to that in the preoperative CT (2). Ikegami et al. (1) claimed that the mRL area should have regenerated because the area was enhanced in the venous phase CT taken 1 month after transplantation. However, we must note that the hypervascular area on CT will not always secure the regenerative potential. Hwang et al. (7) reported 18 donors who donated a left lateral segment liver as a graft. CT scans of all donors were obtained at 1 week and 3 months after surgery. The parenchyma of segment 4 was enhanced in 16 donors (89%) after 1 week. This segment became atrophic in all donors at 3 months. Finally, as they commented in the discussion, the most concerned point in their technique is the increased risk of bile leakage both in the donors and recipients because the transaction line is set near the right anterior Glissonean bundle. Careful discussion may be necessary to analyze whether this new left liver graft is truly adequate option in the living donor liver transplantation. Junichi Kaneko Yasuhiko Sugawara Sumihito Tamura Norihiro Kokudo Artificial Organ and Transplantation Division Department of Surgery, Graduate School of Medicine University of Tokyo Tokyo, Japan Masatoshi Makuuchi Japanese Red Cross Medical Center Tokyo, Japan