Fig. 13.1
Segment 7 was outlined after indigo carmine dye injection into the corresponding portal branch
Torzilli et al. reported the technique of ultrasound-guided vessel compression [40, 41]. The procedure was reported to be feasible in all the eligible patients in their study, and a demarcation territory was obtained in all the patients within 1 min of bimanual IOUS-guided compression. The ultrasound-guided vessel compression technique starts with liver mobilization. Afterward, the most peripheral portal pedicle feeding the tumor is identified by IOUS. With this, the level targeted for compression is detected. At this point, the hemiliver where the tumor is located is partially mobilized to allow handling the liver along the dissection. The surgeon’s left or right hand is then placed below the right or left hemiliver, respectively, while the IOUS probe handled by the surgeon’s other hand is placed above the liver; with IOUS guidance, both hands are positioned at the level of interest which corresponds to the most distal portion of the vessel in relation to its origin but proximal to the tumor to be removed. Using the left/right fingertips and the IOUS probe itself, the surgeon compresses bilaterally the liver at the targeted position, resulting in the compression of the portal pedicle feeding the tumor previously identified. This maneuver is constantly monitored by real-time IOUS probe, and it is maintained until the surface of the targeted liver territory begins to change in color. At that time, the assistant surgeon marks the discolored territory with coagulation, and the compression is released.
Inoue et al. reported a novel application of fused images comprising of a macroscopic view and indocyanine green fluorescence imaging (fusion IGFI) for open anatomical resections making use of the three-dimensional staining ability and a clearer demarcation attained by this method than what can be attained by the conventional technique [42]. Fusion IGFI achieved valid demarcation in 23 of 24 patients (95.8 %), whereas conventional demarcation technique (CDT) achieved valid demarcation in only 10 patients (41.7 %). The IGFI staining technique involves either systemic venous injection of a dye after clamping the inflow to the target vessels (the IV method) or portal puncture and direct injection (the PV method). For the IV method, after dissection of the hepatic hilum, arterial and portal branches of the planned resected hemiliver, section, or segment are exposed and taped. These inflow vessels are first temporarily clamped to confirm the demarcation line and intrahepatic blood flow by US and then ligated and divided for a subsequent intravenous bolus injection of 2.5 mg of ICG. Ten to twenty seconds after the ICG injection, the splanchnic arteries and veins appear enhanced on fusion IGFI, and ICG fluorescence is accumulated in the future remnant territory as counterstaining. For the PV method, after puncturing of the target portal branch, a mixture of 5 ml of indigo carmine, 2.5 mg of ICG, and 0.5 ml of Sonazoid is injected into the branch under contrast-enhanced IOUS guidance with the hepatic artery clamped. The stained region is confirmed by macroscopic inspection, fusion IGFI, and contrast-enhanced IOUS. The IGFI staining technique is chosen on the basis of the CDT required: the IV method is chosen for a hemihepatectomy, sectionectomy, or left-sided segmentectomy where isolation of the target portal branch is usually possible, whereas the PV method is used for a right-sided segmentectomy or resection in which hilar dissection is judged to be difficult due to technical issues.
13.3.4 Preliminary Control of the Vascular Pedicles of the Segment to Be Removed
The main hepatectomies (right and left hepatectomy, right posterior sectionectomy, right anterior sectionectomy) can be performed simply by occlusion of the inflow at the hilum and waiting for a demarcation plane to appear. This approach is especially useful in resection of the segments of the right liver. The right and the left hepatic pedicles are dissected extrahepatically on the undersurface of the liver. Lowering of the liver plate helps in increasing the extrahepatic length of these pedicles. This technique can also be applied in laparoscopic approach of liver resection [43]. By dissecting and tracing the right pedicle distally, the right anterior sectoral pedicle (segments 5, 8) and right posterior sectoral pedicle (segments 6, 7) can be found. Similarly, by dissecting and tracing the left pedicle distally, the segment 4 pedicle and the segments 2/3 pedicle can be found. Further dissecting distally to expose the pedicles inside the liver (segmental pedicles to the liver segments) requires liver parenchymal transection [44–46]. In most cases, ligating the portal pedicle within the targeted segment from the porta hepatis is difficult, and the ligation needs to be done at a point inside the liver parenchyma. IOUS provides a crude demarcation line of the segment on the liver surface, but an accurate identification is still difficult to achieve. Occlusion of the relevant pedicle by a bulldog clamp results in a change of color of the liver segment. The arterial and portal pedicles are ligated and divided at the end of the parenchymal resection. This technique requires more tissue dissection and longer operating time than the other techniques, and it is technically more difficult in patients with cirrhosis and portal hypertension.
13.3.5 Selective Portal Venous Occlusion Using a Balloon Catheter through a Branch of the Superior Mesenteric Vein
This technique is carried out during open surgery [47]. The liver is completely mobilized. A French 6 balloon catheter is inserted into the portal vein via an intestinal branch of the superior mesenteric vein. The catheter is guided into the corresponding branch of the portal vein (either the right or the left) where the HCC is situated, using the surgeon’s hand in the porta hepatis. Once the tip of the catheter is in the intrahepatic portal venous system, further advancement of the catheter into the sectoral and the segmental portal venous branches is done by rotating and advancing the catheter using the trial-and-error method. Guidance of the tip of the catheter into the desired portal venous branch is assisted with ultrasound and the surgeon’s hand in the porta hepatis. When the balloon catheter is in the right position, the balloon is inflated with 3 ml. of normal saline to occlude the venous branch. A few milliliters of methylene blue are injected through the catheter to delineate the liver segment to be resected. Any individual liver segment or sector can be identified by the change or absence of change in color after injection of dye, e.g., if the catheter has been directed into the right liver, injection of dye into either the anterior or posterior sectoral branch can identify the right anterior (segments 5, 8) and posterior (segments 6, 7) sectors. Similarly, if the catheter has been directed into the anterior sectoral branch, injection of contrast will stain either segment 8 or segment 5. Thus, by subtraction, the boundaries of an individual segment can be identified. The line of demarcation is marked on the liver surface with a diathermy. The procedure is repeated if more than one liver segment needs to be delineated. The time required to get the catheter in the right position is around 10 min. The hepatic parenchyma is then transected along the line of demarcation. After hemostasis on the raw liver surface, the balloon catheter is deflated and removed. The hole in the portal venous branch where the catheter entered to delineate the resected liver segment is closed. The branch of the superior mesenteric vein is ligated after the catheter is removed.
13.4 Non-anatomical Liver Resection
Non-anatomical resection is a more suitable operation than subsegment-/segment-based liver resection under two situations: first when the tumor is situated at the border of several segments and second when the tumor is small and is situated peripherally at the edge of the liver. Under such a situation, a wedge excision made in the form of an arch or box shape is a simpler operation than a subsegment-/segment-based liver resection. Wedge excision should not be done in a V shape because of the higher chance of the resection margin being involved by tumor on histological study.
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