Fluorescence-Guided Robotic Segment 8 Superior Liver Resection. Technical Approach to Sectoral Inflow Occlusion

In the last decade, the understanding of segmental and subsegmental liver anatomy with an awareness of clinical superiority associated with parenchymal-sparing hepatectomy is increasing. This leads to a consensus conference and guideline in regards to precision anatomy in minimally invasive liver resection. ¹ Anatomical parenchymal preservation in liver resection requires knowledge in the technique of dissecting and securing vascular inflow. Precise control of the sectoral hepatic artery and portal vein allows for a bloodless liver resection during tumor excision, without the use of Pringle maneuver. In the published literature, technical description of the right anterior portal pedicle dissection during minimally invasive liver surgery is limited. In this video, we demonstrated such technique using fluorescence guidance during a robotic segment 8 superior liver resection.

A 39-year-old woman presented with 7.8 cm enlarging adenoma encompassing portions of segment 8 against the right hemidiaphragm based on radiological imaging. An elective resection of this right superior lesion was then planned. The operation began by partially mobilizing the right hepatic lobe to facilitate access to the right side of the porta hepatis. Dissection to isolate the hepatic artery and portal vein trunk supplying the right anterior sector of the liver was undertaken using a robotic hook electrocautery and bipolar fenestrated forceps. A small bleeding from the right posterior sectoral portal vein was easily controlled using a 4-0 Prolene suture as seen in the video. Once isolated, the right anterior hepatic artery and portal vein were individually looped with a 6-inch 3-0 silk tie. This facilitated the placement of a vascular bulldog clamp on each vessel to gain an inflow occlusion to right anterior sector (segments 5 and 8) of the liver. Demarcation lines on the anterior liver surface were visible, and an indocyanine green (ICG) fluorescence angiography was also performed to further confirm the segmental anatomical borders using negative staining method.

A parenchymal-sparing resection of this lesion was then undertaken with ultrasound guidance. Traction stitches were placed to facilitate the exposure of the deeper liver parenchyma once the liver capsule is opened. With temporary vascular inflow occlusion being applied, bloodless robotic liver resection began mainly by utilizing fenestrated bipolar forceps and a vessel sealer™ (Intuitive Surgical Inc, Sunnyvale, CA, USA). A 15-minute period of inflow occlusion and 5-minute period of reperfusion were applied. A bedside surgeon is using a laparoscopic suction device to irrigate the operative field and to evacuate smoke. Crossing vascular branches smaller than 3 mm were divided using the energy device, while larger branches were divided using clips. Crush-clamp technique was used during the liver resection, similar to that used in an open liver resection. During the deeper parenchyma transection, a V8 (venous 8) branch draining into the middle hepatic vein was encountered and divided using the vessel sealer and clip. A ventral G8 (Glissonean 8) branch going into the specimen was also isolated, clipped, and divided. Finally, the specimen was completely resected from the remaining liver with a meticulous attention to secure hemostasis and biliostasis. This is important to avoid the development of postoperative hematoma or bile leak at the resection site. Upon completion of the liver resection, fluorescence imaging confirmed the absence of unperfused area around the surgical bed. The pathological examination of the specimen was consistent with a 7.2 cm hepatic adenoma with negative resection margins.

In this video, we demonstrated the surgical approach to isolate the right anterior hepatic artery and portal vein located within the right anterior Glissonean sheath. Understanding of the hilar anatomy is important to achieve this task, as well as to minimize potential inadvertent injury to the surrounding structures such as the bile ducts. Extrahepatic Glissonean pedicle approach is a known technique in open hepatic surgery; however, its application is minimally invasive surgery which is much less common due to the required technical precision. Transfissural and Takasaki approach are two other methods often used in securing vascular inflow control during liver resection. In minimally invasive hepatectomy, the use of robotic platform enables precise dissection of the secondary branches of the hepatic artery and portal vein above the hilar plate. When these structures are anatomically located very deep in the liver parenchyma, it is useful to open the surrounding liver parenchyma first to exposure them. ²

The confirmation of an ischemic demarcation area is obtained using the fluorescence imaging, which is one of the several uses of the indocyanine green technology in hepatobiliary surgery. Indocyanine green is a fluorescent iodide-based dye which is used to evaluate the biliary tree, liver perfusion, and function. While liver perfusion assessment and delineation of anatomic regions have been performed using ultrasound, ischemic demarcation, or indigo carmine/methylene blue staining, ICG staining can overcome limitations associated with these techniques, such as rapid washout, lack of precision, non-demarcation in damaged livers, and lack of intraparenchymal fidelity. Indocyanine green can be used to fluoresce target segments/tumors (positive staining method) or counterstain normal liver tissue leaving areas of interest unstained (negative staining method).^3,4

In conclusion, fluorescence guidance technique to achieve a parenchymal-sparing liver resection of segment 8 using robotic approach is safe and feasible. Understanding of porta hepatic anatomy is important to gain proficiency in performing this step. This technique will have a future role in liver cancer surgery as we move toward precision hepatectomy.