Right hemihepatectomy preserving the fluorescently visible paracaval portion of the caudate lobe.

The paracaval portion (PC) of the caudate lobe is a small area of the liver located in front of the inferior vena cava. Conventional right hemihepatectomy (RH) along the Rex-Cantlie line involves resection of not only the anterior and posterior sections but also the PC behind the middle hepatic vein (MHV). However, to preserve the future liver remnant volume as much as possible, PC-preserving RH may be beneficial in selected patients. We injected an indocyanine green (ICG) solution in the PC portal branch under intraoperative ultrasonography (IOUS) guidance and performed an RH preserving the fluorescently visible PC in a patient with liver metastasis. The patient was a 47-year-old male with a 24 ×10 cm metastatic hepatic tumor from sigmoid colon cancer. CT volumetry revealed that the left hemiliver excluding the caudate lobe was 55%, and the caudate lobe was 5.3%. Before hepatic transection, the ICG solution was injected into the PC portal branch under IOUS guidance. During hepatic transection, the PC was identified as a fluorescent area behind the MHV using a near-infrared imaging system. Thus, the anatomical right-side boundary of the caudate lobe was clearly found. Following RH, the PC was preserved as a fluorescently visible area. The patient had an uneventful recovery. RH preserving the fluorescently visible PC of the liver is a feasible procedure.

Demonstration of the right-side boundary of the caudate lobe in a liver cast.

There have been historical arguments about the boundary of the caudate lobe of the liver. Kumon M first advocated the definition of the caudate lobe based on the portal segmentation of the liver in 1985, and classified it into three parts, Spiegel lobe, paracaval portion and caudate process. Prof. Couinaud defined the dorsal liver as a union of segments I and IX in 1994, based on the spatial position to the major hepatic veins, hilar plate and inferior vena cava. In Couinaud's classification, right-side of the dorsal liver is supplied by the branches from the posterior and anterior sections. In the present study using a liver cast, we found a paracaval branch of the portal vein branching from the right portal vein on the dissecting plain along the Rex-Cantlie's line. We also found several branches from the posterior portal vein to the right-side of the paracaval portion, but they should be defined to belong to the posterior sections.

Laparoscopic liver resection for primary liver cancers originating in the paracaval portion of the caudate lobe: a preliminary retrospective analysis with 31 patients.

Paracaval-originating cancers have been considered a contraindication for laparoscopic liver resection (LLR). This study aimed to explore the safety and feasibility of LLR in the treatment of paracaval-originating cancers. This study included 11 patients who underwent LLR and 20 who underwent open liver resection (OLR) for paracaval-originating cancers between May 2010 and November 2020. The outcomes of the procedures were retrospectively analyzed. There were no cases of perioperative death or conversion to laparotomy. The LLR group had an earlier postoperative feeding time, shorter postoperative hospital stay, and lower total bilirubin levels on the first day after surgery. No significant differences in the incidence of overall postoperative complications were noted between the LLR and OLR groups, but the incidence of grade IIIa complications was significantly higher in the LLR group than in the OLR group. Tumor recurrence occurred in 4 of 11 patients in the LLR group and in 11 of 20 patients in the OLR group. LLR for the treatment of paracaval-originating cancers is safe and feasible in selected patients.

Laparoscopic anterior hepatic transection for resecting lesions originating in the paracaval portion of the caudate lobe (with videos).

BACKGROUND: The paracaval portion of the caudate lobe is located in the core of the liver. Lesions originating in the paracaval portion often cling to or even invade major hepatic vascular structures. The traditional open anterior hepatic transection approach has been adopted to treat paracaval-originating lesions. With the development of laparoscopic surgery, paracaval-originating lesions are no longer an absolute contraindication for laparoscopic liver resection. This study aimed to evaluate the safety and feasibility of laparoscopic anterior hepatic transection for resecting paracaval-originating lesions. METHODS: This study included 15 patients who underwent laparoscopic anterior hepatic transection for paracaval-originating lesion resection between August 2017 and April 2020. The perioperative indicators, follow-up results, operative techniques and surgical indications were retrospectively evaluated. RESULTS: All patients underwent laparoscopic anterior hepatic transection for paracaval-originating lesion resection. The median operation time was 305 min (220-740 min), the median intraoperative blood loss was 400 ml (250-3600 ml), and the median length of postoperative hospital stay was 9 days (5-20 days). No conversion to laparotomy or perioperative deaths occurred. Six patients had Clavien grade III-IV complications (III/IV, 5/1). Two patients developed tumor recurrence after 13 months and 8 months. CONCLUSION: Although technically challenging, laparoscopic anterior hepatic transection is still a safe and feasible procedure for resecting paracaval-originating lesions in select patients.

Definition of the caudate lobe of the liver based on portal segmentation.

Models of liver corrosion were developed by injecting colored Mercox, epoxy resin, silicon rubber and other materials into the portal vein, hepatic artery, bile duct and hepatic vein of autopsied livers. The glissonean or venous branches that obstructed the view of the caudate lobe of the liver were subsequently removed. The detailed anatomy of the caudate vessels was studied and the three parts of the caudate lobe (Spiegel lobe, paracaval portion and caudate process) were defined based on portal segmentation. Caudate portal branches should be defined as dorsal branches arising from the main trunk, or from the first order branches of the portal vein covering the hepatic region in front of the inferior vena cava. The hepatic region, where the internal branches from segment eight cover the front of the inferior vena cava, should be defined as segment eight, and not as the paracaval portion. Prof. Couinaud defined the right side of the caudate lobe as segment IX based on the spatial position; however, this classification of the caudate section seemed to lack consistency with that of other hepatic segments, which were defined based on portal segmentation. We have sustained the dogma that any hepatic segment should be defined based on portal segmentation, and our classification of the definition and boundary of the caudate lobe, which was published in 1985, has sufficient consistency to be used as an international standard.

Anatomical Boundary Between the Caudate Lobe of the Liver and Adjacent Segments Based on Three-Dimensional Analysis for Precise Resections.

BACKGROUND: Right hemihepatectomy or systematic resection of segment 7 or 8 involves partial resection of the paracaval portion of the caudate lobe. However, the boundary between the caudate lobe and segment 7 or 8 remains unclear. We examined the anatomical territory of the caudate lobe with special reference to the boundary between the paracaval portion and segment 7 or 8 for precise anatomical hepatectomies. METHODS: We enrolled 63 consecutive healthy donor candidates for living-donor liver transplantation from 2012 to 2014 in this study. The caudate lobe was defined according to Kumon's subdivision system, and the boundary between the paracaval portion and segment 7 or 8 was investigated based on three-dimensional computed tomography scan images using SYNAPSE VINCENT®. RESULTS: The paracaval portion of the liver protruded on the liver surface underneath the right diaphragm on the ventral side of the right hepatic vein (RHV) in 10 participants (16%) and on the dorsal side of the RHV in 9 participants (14%). A branch of the RHV, the "paracaval vein," was found in all 63 participants and ran longitudinally along the right border of the paracaval portion (n = 30, 48%) and within segment 7 (n = 16, 25%) or segment 8 (n = 17, 27%). CONCLUSIONS: The paracaval portion of the liver protruded on the liver surface underneath the right diaphragm in one third of our participants. The paracaval vein can be a landmark for the boundary between the caudate lobe and the segment 7 or 8 in half of the cases.