CHAPTER 2 LIVER RESECTION

INTRODUCTION

Partial hepatectomy is possible because liver regeneration is rapid (Plate 1) and because the liver is segmental in structure (Plate 2).

Plate 1 Prometheus Bound. Greek myth: Prometheus stole fire from Zeus and was punished by being chained to a rock. Each day an eagle would feast on his liver, and each night his liver would regenerate in time for the eagle’s return. (Pieter Paul Rubens, Philadelphia Museum of Art.)

Plate 2 The segmental structure and vasculature of the liver. Top left, Corrosion caste showing segments of the liver

(Courtesy Claude Couinaud). Top right, Duplex ultrasonography of the liver showing the major hepatic veins. Bottom left, Venous anatomy of the liver shown on magnetic resonance imaging of the explanted liver at the time of transplantation. Bottom right, Illustration from Anatomia Hepatis (Francis Glisson, 1654).

Hepatic resection for removal of lesions of the liver may be necessary for a wide variety of conditions (Table 2-1).

TABLE 2-1 Most Common Conditions for Which Liver Resection May Be Used for Therapy

GENERAL PRINCIPLES

BENIGN DISEASE

Partial hepatectomy for the removal of benign tumors or cysts of the liver should be performed only for symptomatic patients, when there is doubt as to the diagnosis, or for tumors with known malignant potential. Removal of liver tissue should be kept to a minimum, and the use of techniques for enucleation of such tumors is often appropriate.

Liver resection may be necessary in the management of some complex benign biliary strictures, especially when associated with unilateral liver atrophy and a variety of other benign biliary conditions, including the removal of intrahepatic stones sometimes in association with recurrent pyogenic cholangitis and in some cases of Caroli disease.

MALIGNANT DISEASE

Partial hepatectomy as treatment for malignant tumors of the liver must be guided by the principle of complete tumor removal with a margin of parenchymal transection clear of the tumor. Despite the need to resect with clear margins, every effort should be made to minimize removal of functional liver tissue.

Wedge resections carry an increased local recurrence rate, and the principle of achieving clearance is best met by performing resection along anatomic lines.

Gallbladder carcinoma and cholangiocarcinoma at the confluence of the hepatic bile ducts frequently occlude biliary flow, and resection may be compromised not only by obstructive jaundice but also by infection that may have been introduced before surgery as a result of interventional radiologic or endoscopic procedures. Hilar blood vessels may be involved by tumor, and vascular resection and reconstruction may be necessary.

PRINCIPAL HAZARDS

The main hazards of hepatic resection are biliary leakage and bleeding. Biliary leakage is a particular problem with patients in whom biliary reconstruction is necessary. Bleeding from the hepatic veins and the inferior vena cava (IVC) during parenchymal transection is a major concern. Bleeding is especially likely to occur during major resection for high and posteriorly placed tumors (Fig. 2-1).

Figure 2-1 A, CT scan shows an enormous tumor occupying the left liver and extending beyond the principal plane into the right liver. There is apparent involvement of the vena cava or the hilar structures. B, Selective hepatic artery angiogram reveals the gross size of the tumor within the left liver. C, Late-phase portogram shows gross displacement of the main trunk of the portal vein and its right branch (arrows). There is no filling of the left branch of the portal vein. Anteroposterior (D) and lateral (E) views of the inferior vena cava reveal severe compression but no tumor invasion. The tumor proved to be a fibrolamellar hepatocellular carcinoma and was treated by extended left hepatectomy. Note: Direct angiographic techniques have been supplanted by dynamic computed tomography and magnetic resonance imaging.

Postoperative Functional Hepatic Reserve

A noncirrhotic, healthy patient may tolerate a resection of 80% of liver volume. The enormous regenerative capacity enables functional compensation within a few weeks.

There is virtually no risk if most of the specimen volume has been replaced by an extensive tumor mass. In such patients, compensatory hypertrophy of the unaffected residual liver already has occurred, and the loss of functional parenchyma is limited. A comparable resection performed for multiple or unfavorably located smaller lesions carries a much greater risk of postoperative liver failure. More recent approaches have advocated the use of portal vein embolization in this situation, but there is little evidence that portal vein embolization is associated with improved postoperative results in patients with normal liver parenchyma.

In patients with a steatotic liver, there is an increased risk. Portal vein embolization may prove to be justified in this group of patients.

In the cirrhotic liver, liver regeneration is much less effective, and impairment of liver function is greater, may last longer, and may result in liver failure. Nonspecific postoperative surgical complications, such as abdominal infection, may trigger postoperative liver failure. In cirrhotic patients, portal hypertension is augmented and is related to the amount of parenchyma removed. The increase in portal hypertension also may be related to the increased risk of variceal bleeding. Although there is evidence that major hepatic resection can be performed safely in cirrhotic patients with Child’s A liver function, portal vein embolization may improve hepatic functional reserve in the remnant of the liver.

Infection

There is a serious risk of infection after liver resection in patients with biliary obstruction, especially in the presence of previous radiologic or endoscopic intubation and in cirrhotic patients.

SUMMARY

1. Noncirrhotic patients in whom clearance of tumor or removal of benign lesions can be obtained without compromising hepatic arterial and portal venous inflow, hepatic venous outflow, or biliary drainage to or from the remnant are suitable for hepatic resection.

2. Cirrhotic patients with one or two tumors should be considered for resection. Resection is contraindicated in patients with multiple nodules. Liver function is the major risk factor, and resection should not be carried out in patients with a serum bilirubin greater than 2 mg/dL or in the presence of clinically detectable ascites. Evident portal hypertension is also a contraindication.

BASIC TECHNIQUES

ANATOMY AND CLASSIFICATION

The liver is divided into sectors that are formed from liver segments supplied by branches of the portal triads and drained by hepatic veins (see Chapter 1). Partial hepatectomy involves removal of one or more segments accomplished by isolation of the relevant portal pedicle, severance of the relevant hepatic veins, and removal of the associated liver tissue.

Essentially there are five types of major resection (Figs. 2-2 and 2-3). The nomenclature of these operations is based on the anatomic descriptions of Couinaud (1954, 1957) and Bismuth (1982) (Table 2-2). The alternative, more commonly used terminology of Goldsmith and Woodburne (1957) also is listed. A newer terminology has been proposed by the International Hepato-Pancreatico-Biliary Association (Strasberg et al., 2000), but it is not used in this text or in the narrative supporting the videos.