**7. Techniques of liver parenchyma transection for HCC**

#### **7.1 Finger fracture technique**

Hepatic transection remained a challenge for all surgeons, for more than a century. The first scheduled hepatectomy was performed in 1888 from Carl Langenbuch [24]. Liver surgery was minimal thus, up to the 20th century, when Pringle maneuver was first presented, for bleeding control during emergency hepatic resections [14]. Hepatectomy is particularly difficult in cirrhotic liver due to the fibrotic nature of liver tissue. The finger fracture technique, the liver tissue is fractured and crushed by the thumb and index finger followed by isolating and ligating the resistant intrahepatic vascular and ductal structures [15].

#### **7.2 Crash-clamp (Kelly) technique**

The finger fracture technique, in which the parenchymal transection is done by crushing the parenchyma between the thumb and another finger isolating vessels and bile ducts which were ligated and divided, after liver inflow occlusion, was afterward improved using a surgical instrument such as the Kelly clamp [25]. Using the Kelly clamp technique during hepatic resection of cirrhotic liver with HCC can be performed in less operative time, while help obtaining a clearer operative field [26].

#### **7.3 Radiofrequency ablation (RFA) assisted technique**

RF assisted hepatectomy, for the treatment of hepatocellular carcinoma amongst other liver malignancies, was first implemented by Habib's group at Hammersmith Hospital, London, UK [27]. Ever since, RFA has been widely used for the in-situ ablation of unresectable liver and other solid organ tumors [28], but it has now been incorporated into routine liver resection, being used to create a line of coagulative necrosis that can subsequently be divided with a scalpel with relatively little blood loss [29]. In recent years, the continuous use and development of RFA ablation in liver surgery have produced satisfactory results in the treatment of small HCC. It can also block small and medium-sized blood vessels in the liver through thermal coagulation, so it has been used in liver resection to reduce bleeding. However, the use of this technique remains controversial due to reported perioperative outcomes and complications; some studies have reported that radiofrequency-assisted liver resection causes severe postoperative liver dysfunction, and the incidence of postoperative complications is higher than that of simple hepatectomy [30].

### **7.4 Cavitron ultrasonic aspirator (CUSA) technique**

Cavitron Ultrasonic Surgical Aspirator (CUSA), also known as Ultrasonic Dissector, was first popularized by Hodgson et al. in 1979 [31]. The ultrasonic waves generate energy to fragment and aspirate parenchymal tissue. Contact of the oscillating titanium tip instigate fragmentation of hepatocytes owing to the high-water content while, selectively sparing the blood vessels and bile ducts because of poor tissue water content. In the liver parenchyma, anatomically, both the Glissonean cords as the inflow system and the hepatic veins as the outflow system show branching, like a tree. Both systems rise from the dorsal side, where they are relatively close to each other, and branch towards the ventral side. Any liver resection can become simpler and safer by selectively dissecting in a plane, where no Glissonean cord runs, such as an intersegmental plane. When such planes are dissected with the CUSA, the hepatic veins, which are relatively thicker and can be more easily identified than those that appear when the other parts are divided, usually appear in the cutting plane. Further, some thinner branches, which cross the cutting plane and flow into the exposed thicker hepatic vein, should be cut at the confluence without incurring a split injury [32]. It has been proven that CUSA selectively destroys and aspirates parenchyma, leaving vessels and biliary ducts almost intact with larger vessels and large intrahepatic bile ducts amenable to ligation or clipping [33].

#### **7.5 Sealing device-assisted technique**

The LigaSure Vessel Sealing System (Valleylab, Boulder, CO, USA) is a hemostatic and dissecting tool, which is able seal blood vessels (up to 7 mm in diameter), by denaturing collagen and elastin within the vessel wall and in the surrounding connective tissue [34]. LigaSure can be safely applied in any type of liver and hepatectomy combined with the crush clamping method.

The Harmonic Scalpel (Ethicon Endo-Surgery, Cincinnati, OH, USA), utilizes ultrasonic vibration of two blades causing destruction of hydrogen bonds. This disturbance of hydrogen bonds causes protein denaturization coagulating small vessels of 3 mm diameter. The parenchyma is then transected with blade movement in a saw-like fashion [35].

#### **7.6 Tools for resection**

As mentioned above, the techniques used in liver transections were described in reports and were widely used. From the finger fracture technique described by Lin [15] to the use of the blunt end of a hemostat by Ogilvie [36] and the use of the blunt edge of a scalpel by Quattlebaum, a common goal can be perceived. The identification of different tissues, parenchyma vs. vessel, via the means of blunt dissection. Perseverance of great vessels and following appropriate ligation was the main aim of hepatic surgeons to avoid uncontrollable hemorrhage. Avoiding such complication could mean avoiding death.

In 1928 the first electrocautery device was invented. The Bovie knife, known from its inventors Bovie and Cushing, is the tool of choice up to this day by majority of centers when it comes to hemostasis and partial resection of the liver parenchyma [37]. A few years later, the need of new and perhaps more effective ways for liver surgery was explored.

Another technique that originates from compression characteristics of hemostasis is the hemostatic clamp. During the years, many surgeons have used such

clamps. Back in 1960s the first clamp used in liver surgery was described by Stucke [38]. Variation of such were seen within the same decade. It needed the efforts of Nakayama to reach a newly designed clamp, specific to the liver [39].
