Major hepatectomy and extended hepatectomy

Introduction

Major hepatectomy is typically defined as a resection of three or more contiguous hepatic segments. Most commonly, this definition encompasses right and left hemihepatectomies and extended left and right hepatectomies. Extended hemihepatectomies can include a small subsegmental portion of the adjacent parenchyma or a more formal “trisectionectomy” where the adjacent segments (i.e., segment IV for a right sided resection, or segments V/VIII for a left sided resection) are included in the resection. Further, the caudate lobe may be included in any of these resections.

The term major hepatectomy is an appropriate description of these operations given that they are technically challenging and are associated with significant rates of postoperative morbidity. Among the spectrum of liver resections, these operations are associated with the highest rates of postoperative morbidity, including postoperative hepatic failure and other life-threatening complications. This chapter reviews the technical aspects of these operations. Operations requiring biliary or vascular resection (see Chapters 118A to 119A and 119B ) or operations for living donor hepatectomy (see Chapter 121 ) are not covered in this chapter. Although this chapter does not focus on minimally invasive hepatic resections (see Chapter 127E ), the same principles apply to a major hepatic resection regardless of surgical approach.

Indications

Major hepatectomy is most commonly indicated for malignant tumors of the liver and biliary tree (see Chapter 89, Chapter 90, Chapter 91, Chapter 92 and 101 ). Rarely, large symptomatic or premalignant benign tumors are indications for a major hepatectomy (see Chapters 88 and 101 ). It should be stressed that in the contemporary era, a diagnostic hepatic resection for an indeterminate liver mass is rarely indicated—particularly with modern imaging and access to accurate pathology from percutaneous biopsy (see Chapter 13, Chapter 14, Chapter 15 and 23 ). Last, some less common indications for major hepatectomy include en bloc resections of perihepatic tumors (e.g., diaphragm, adrenal, retroperitoneum, stomach, duodenum), as well as management of certain benign conditions, including infections of the liver or biliary tree (see Chapter 11 ), trauma, and complex bile duct injuries (see Chapter 113 ).

In a sense, major hepatectomy should be an operation of last resort. Whenever possible, parenchymal-sparing operations that remove less liver tissue should be the operation of choice (see Chapters 102 and 118B ). The reason for this is simple: Although parenchymal-sparing resections can be more challenging, the removal of less hepatic parenchyma is consistently associated with less postoperative morbidity. Specifically, removal of three or fewer segments of liver rarely results in liver failure, which is the most life-threatening complication of hepatic resection. Therefore a major hepatectomy should only be performed when the pathology involves inflow and outflow vessels that mandate removal of a hemiliver or more. It is often difficult to decide between parenchymal-sparing resections and major resections; it is therefore incumbent on the surgeon to weigh the risks (morbidity) and benefits (completeness of resection) of either approach.

The hepatic surgeon should also have a good sense of volume of hepatic parenchyma. In general, right-sided major hepatic resections are the largest volume resections. Typically, the right hemiliver encompasses approximately two-thirds of the liver and the right liver combined with segment IV can occupy over 80% of the liver. Left hemiliver resections, even when somewhat extended, are relatively low-volume resections. The volume of the right posterior sector is variable but the majority of left trisectionectomies leave a future liver remnant (FLR) of over 30%. Since it is the volume of residual liver parenchyma that is directly responsible for posthepatectomy morbidity, the surgeon should have a sense of these relative volumes and the resources to directly measure the relative volume of the planned hepatic resection (see Chapters 4 and 102 ).

Preoperative planning

Workup of specific diseases is covered in other chapters (see Chapter 12 ). For major hepatic resections, however, is it mandatory to have high-quality, multiphasic (arterial and portal venous phases) cross-sectional imaging to assess the extent of disease, vascular proximity, and anatomic variation (see Chapter 13 ). The surgeon should be able to assess the branching patterns of the hepatic veins, portal veins, and hepatic artery, as well as specific issues related to the proximity of the pathology being treated. Both magnetic resonance imaging and computed tomography (CT) can provide the necessary level of detail for preoperative planning, and each has specific advantages in different clinical scenarios.

Biliary anomalies are relatively common and preoperative recognition of specific branching abnormalities is important (see Chapter 2 ). The most common biliary anomalies involve right sectoral ducts draining either to the left bile duct or as low insertions into the common hepatic/bile duct. Therefore imaging of the biliary tree is most relevant for left-sided major resections so as to be prepared for right sectoral ducts that may be injured during a left hepatectomy. It can be argued that hilar branching of the biliary tree should be known in every case, but it is not often relevant in right-sided major resections. Classically, magnetic resonance cholangiopancreatography (MRCP) with gadolinium contrast is the imaging study of choice to assess the biliary tree (see Chapter 20 ), but MRCP with Eovist contrast and specific CT protocols can also be used to delineate biliary anatomy (see Chapter 16 ).

Assessments of overall liver function and the size and function of the FLR are critical when planning major hepatic resections. Details of the assessment and management are covered in other chapters (see Chapters 4 , 101 , and 102 ). The Child-Pugh scoring system is a simple, easily obtainable, and clinically useful measure of hepatic function. However, it is critical to also assess patients for evidence of portal hypertension (see Chapters 5 and 74 ), which is not included in the Child-Pugh criteria and can be present even in the face of normal synthetic function. Portal hypertension can result from chronic liver disease or extensive treatment with systemic chemotherapy, and can often be diagnosed by virtue of readily available clinical findings such as splenomegaly, thrombocytopenia, and evidence of varices. In general, large-volume resections should only be performed in patients with Child-Pugh A liver function and no evidence of portal hypertension, as the presence of either major synthetic dysfunction or portal hypertension portends prohibitive operative risk. Direct measurement of FLR volumes should be liberally assessed, even when the future liver remnant appears adequate. FLR volumes of less than 25% to 30% are associated with a significant risk of posthepatectomy liver failure, with even higher volume thresholds in patients with chronic liver disease or chemotherapy-related hepatic injury. Strategies to increase both the volume and function of the FLR such as portal vein embolization must be considered when volumes are not adequate (see Chapter 102C ). Assessment of absolute changes in volume and the kinetics of such growth are very good markers of liver function and improve the safety of major resections.

Relevant anatomy (also see Chapter 2 )

Hepatic artery

The common hepatic artery typically branches off the celiac axis, coursing to the right along the superior border of the body of the pancreas (see Fig. 2.37 ). After giving off an inferior branching gastroduodenal artery and then the right gastric artery (with somewhat variable origins), the proper hepatic artery then branches into the right and left hepatic artery. The proper hepatic artery can be of variable distance and may not exist at all with an immediate bifurcation after the gastroduodenal artery. In its typical course, the left hepatic artery runs cephalad along the left border of the porta hepatis toward the base of the umbilical fissure. The distal left hepatic artery most commonly branches at the base of the umbilical fissure into a segment IV and a left lateral section branch (segments II and III). Alternatively, the segment IV branch can arise off of the proximal right hepatic artery where it runs into the right border of the umbilical fissure. In this case, the apparent “left hepatic artery” only supplies the left lateral section. The right hepatic artery courses cephalad, to the right, and typically (90%) posterior to the common hepatic bile duct. Alternatively, when the right hepatic artery runs anterior to the common hepatic duct (10% of patients), it is the most anterior structure in the right side of the porta hepatis. Branching of the right hepatic artery into sectoral branches often occurs outside of the hepatic parenchyma—proximal to the invagination of Glisson capsule—and can be dissected and encircled in the porta hepatis if necessary.

Anomalies of the hepatic arterial system are common. Replaced vessels originate from a branch other than the hepatic artery and completely replace the blood supply to a hemiliver. Accessory vessels originate from a branch other than the hepatic artery and supply a portion of a hemiliver in conjunction with the standard arterial inflow. Most commonly, replaced and accessory right hepatic arteries originate from the superior mesenteric artery and course posteriorly along the right side of the porta hepatis lateral to the portal vein. Most commonly, replaced and accessory left hepatic arteries originate from the left gastric artery and run through the gastrohepatic ligament, where they enter the liver at the left side of the base of the umbilical fissure. The common hepatic artery can also be replaced to the superior mesenteric artery where, most commonly, it runs cephalad and anteriorly between the portal vein and the common bile duct, entering the anterior portion of the porta hepatis. Right and left hepatic arteries can also originate proximal to the gastroduodenal artery from the common hepatic artery. It is important to realize that nearly any branching pattern is possible, and this anatomy should be known from preoperative imaging and anticipated at surgery (see Chapters 2 and Chapter 13, Chapter 14, Chapter 15 ).

Portal vein

The portal vein forms from the confluence of the splenic vein and superior mesenteric vein. From its origin, the portal vein courses toward the liver posteriorly and to the right within the porta hepatis. At the base of the liver between the caudate lobe and the base of segment IV, the portal vein most commonly splits into a long transverse, leftward running left portal vein and a shorter, more cephalad coursing right portal vein. The first branches of the right and left portal vein are those to the caudate lobe; these must be identified before encircling the right or left portal vein. The caudate branch off of the right portal vein arises proximally and supplies the caudate process. The left portal vein gives off a significant caudate branch that supplies the left side of the caudate just before curving into the umbilical fissure, adjacent to the insertion of the ligamentum venosum. There are small segment IV portal vein branches that branch superiorly off of the transverse portion of the left portal vein and are visualized when completely mobilizing the left portal vein or when lowering the hilar plate. The left portal vein typically branches into the segments of the left liver intrahepatically. The right portal vein most commonly gives off an anterior and posterior sectoral branch, which can be dissected in the porta hepatis.

There are numerous anomalous branching patterns that must be anticipated by careful review of preoperative imaging (see Fig. 2.38, Fig. 2.39, Fig. 2.40, Fig. 2.41, Fig. 2.42, Fig. 2.43 ). The posterior sectoral branches often originate without a common posterior sectoral portal vein. In 5% to 10% of patients, an early branching posterior sectoral vein directly off the main portal vein will be followed by the right anterior sectoral branch and left portal vein. In the most dangerous situation (albeit very rare; <1%), a single branch enters the substance of the liver; after giving off a right portal vein (or separate origins of right anterior and posterior sectoral branches), it courses to the left yielding the left portal vein. With a single vein in the porta hepatis, it can be easy to mistakenly divide the whole portal venous anatomy during a major hepatectomy in this situation. In addition to these anomalies, there are innumerable variations on branching patterns that need to be anticipated (see Chapter 2 ).

Preservation of portal venous inflow is critically important for postoperative liver regeneration, particularly for major resections. Compromise of portal venous inflow in any meaningful way can result in postoperative liver failure.

Bile duct

The common bile duct is located anteriorly along the right border of the porta hepatis. The common hepatic duct is defined as the duct cephalad to the variable insertion of the cystic duct. Relevant to dissection in the porta hepatis is the fact that the biliary tree is supplied by hepatic artery branches that run along the lateral borders of the duct (3 and 9 o’clock branches). Since the function and viability of the ductal wall is reliant on this arterial inflow, skeletonization of the biliary tree along its lateral aspects can result in ischemia with the potential for strictures or necrosis. The bile duct branches into a long, left bile duct that courses transversely along the base of segment IV where it enters the umbilical fissure and gives off segmental branches to the left liver. The right bile duct runs into the substance of the right liver at the base of the cystic plate and is short with early branching into sectoral/segmental branches. Similar to the portal vein, both the right and left bile ducts provide biliary drainage to the caudate lobe. Left-sided caudate branches drain into the left bile duct, whereas branches from the caudate process/right side of the caudate drain into the right bile duct. Myriad biliary branching anomalies exist (see Fig. 2.25 ); the most relevant to major hepatectomy include sectoral branching of right branches into the left bile duct. A relatively common anomaly involves the right posterior or anterior sectoral duct entering the left bile duct. These left-sided insertions of right sectoral ducts are particularly relevant for left-sided major resections, as it can be easy to injure, narrow, or ligate right-sided biliary branches. Sectoral branches can also exit the liver and insert into the common hepatic/bile duct as low entry sectoral ducts. Unexpected encounters with these anomalous sectoral branches can be confusing during major hepatectomy and may require biliary exploration and/or cholangiogram to determine the exact anatomy in order to proceed with safe resection (see Chapters 20 and 24 ). In general, and whenever possible, it is safest to divide and ligate biliary branches intrahepatically to ensure protection of the contralateral bile duct branches. Contralateral biliary injuries during major hepatectomy can be a source of catastrophic morbidity.

You're Reading a Preview

Become a Clinical Tree membership for Full access and enjoy Unlimited articles

Become membership

If you are a member. Log in here