Background

Liver resection is the main treatment for most patients with primary and metastatic liver malignancies. Considering intraoperative peculiarities of tumor process, one of the main objectives is preservation of the largest possible liver parenchyma [1, 2]. This makes it possible to prevent postoperative liver failure and to ensure the possibility of redo resections in case of recurrence. Analysis of liver anatomy, development of computer programs for simulation of surgery, as well as widespread use of intraoperative ultrasound were followed by development of segmental liver resection. The most difficult preoperative planning of surgical intervention arise in patients with tumor nodes adjacent to the great liver vessels [3]. In some cases, extended resection is performed for a relatively small neoplasm due to the risk of impaired blood supply. We report one of the approaches to clinical situation that occurs in patients with a tumor in liver segment VII and/or VIII with involvement of the right hepatic vein and its branches. In most cases, surgeons perform right-sided hemihepatectomy. A possible rarer alternative is resection of liver and hepatic vein followed by reconstruction for adequate venous outflow from liver segment VI and lateral part of segment V [4 — 6]. The authors described ligation of the right hepatic vein without reconstruction. However, this is possible only in the presence of a short hepatic vein of large diameter (over 5 mm, the so-called inferior right hepatic vein) [6 — 9]. Considering own clinical data, we have shown that intrahepatic collaterals existing and arising in early postoperative period can ensure an adequate venous outflow into the middle hepatic vein, short hepatic veins during resection of liver segment VII and/or VIII, right hepatic vein and its branches without reconstruction and in the absence of inferior right hepatic vein.

Objective. To improve the treatment outcomes in patients with primary and metastatic liver tumors localized in segments VII-VIII involving the right hepatic vein and its branches.

Material and methods

There were 16 surgical interventions including resection of liver segment VII and/or VIII with resection of the right hepatic vein and its branches without reconstruction. All procedures were carried out at the Department of Liver and Pancreatic Tumors of the Blokhin National Medical Cancer Research Center for the period 2016 — 2020. The cause of surgery was colorectal cancer liver metastases in 8 patients, hepatocellular carcinoma in 2 cases, angiomyolipoma in 1 case and metastases of uterine cancer in 1 patient. Minor liver resection was additionally performed in 5 cases. Median age of patients was 58 years (range 28-78) years. There were 10 women and 6 men. Preoperative chemotherapy was performed in 6 patients. Median number of courses was 10 (range 4-24).

Fig. 1. Colorectal cancer metastasis in liver segment VII in projection of distal part of the veins forming the right hepatic vein (preoperative contrast-enhanced CT).

Comprehensive preoperative examination obligatory included contrast-enhanced CT or MRI of the abdomen. Considering these data, we estimated spread of tumor, involvement of the right hepatic vein and its branches. In 2 cases, a complete blockade of the right hepatic vein was diagnosed. Laparotomy was performed via midline and right subcostal approach in all cases. Short veins were maximally preserved during mobilization of the right liver lobe. Right hepatic vein was mobilized within its orifice and cut off using endoscopic stapling device or transected and sutured with an interrupted suture. Intraoperative ultrasound was followed by liver parenchyma dissection with an ultrasonic scalpel and ligation of the venous tributaries forming the right hepatic vein.

Fig. 2. Proximal mobilization of the right hepatic vein.

Fig. 3. Intersection of the right hepatic vein in distal part.

We have retrospectively analyzed surgery time, mean time and incidence of hepatoduodenal ligament clamping (Pringle maneuver), intraoperative blood loss, postoperative morbidity and hospital-stay.

Results

Median surgery time was 150 (80-220) min, intraoperative blood loss — 400 (100-2000) ml. Afferent blood flow was blocked in 4 patients for 14 (12-25) min. None patient had intraoperative signs of impaired venous outflow. Uniform venous circulation in liver was determined on the 5th postoperative day in all cases. Biliary fistula in postoperative period occurred in 1 patient. No complications were noted in other cases. A patient with hepatocellular carcinoma had ascites in 4 weeks after surgery with effective conservative control. Examination revealed reactivation of viral hepatitis C on the background of liver cirrhosis. There was no postoperative mortality. Median length of postoperative hospital-stay was 13 (range 9-19) days.

There were no specific complications in long-term postoperative period that could be associated with venous outflow blockade through the right hepatic vein. Median follow-up period was 12 (range 2-37) months. Two patients underwent redo liver resection (segments 6 and 4b-5). Intraoperative and subsequent postoperative morphological examination after redo surgery revealed no atrophic changes in liver parenchyma.

Fig. 4. Development of collateral circulation (contrast-enhanced CT in 4 months after surgery).

Discussion

The development of modern surgical technologies in hepatology is directly related to more detailed anatomical and pathophysiological studies. One of the main purposes of these researches is analysis of compensatory processes in liver after resection. Surgical interventions based on the concept of segmental liver anatomy made it possible to introduce liver resection surgery into daily clinical practice due to significant decrease in intraoperative blood loss and incidence of postoperative liver failure [10].

Isolated resection of liver segments VII-VIII is rarely described among various types of liver resection (less than 1%) [7]. The main reason is associated with localization of these tumors and frequent involvement of the right hepatic vein and/or its branches. Resection of these vessels is theoretically associated with possible impairment of adequate venous outflow from liver segment VI and lateral part of segment V, subsequent fibrosis of liver parenchyma, cirrhosis and atrophy [11, 12]. The risk of the above-described abnormalities is also increased because the vast majority of patients undergo surgery under impaired liver function following multiple courses of chemotherapy and chronic viral hepatitis. One of the measures for prevention of this complication is restoration of venous blood flow through veno-venous anastomosis with vascular prostheses or direct implantation of the right hepatic vein into inferior vena cava [11, 13, 14]. Dissection of intrahepatic part of the right hepatic vein is difficult manipulation and not feasible in case of lesion of its branches.

Radiofrequency or microwave ablation of tumors is not usually possible in these situations due to adherence of neoplasm to the great veins and technical difficulties associated with approach [15, 16]. An efficacy of stereotactic radiotherapy is unclear and currently discussed [17].

Some authors report safe resection of liver segments VII-VIII and right hepatic vein without blood flow restoration in case of short hepatic vein of a large diameter (over 5 mm). It is the so-called inferior right hepatic vein. This vein can be visualized during preoperative CT or ultrasound [6 — 8, 18]. Inferior right hepatic vein ensures additional venous outflow from inferior parts of the right lateral and paramedian sectors [18]. Champetier J. et al. reported this variant of vascular anatomy in 9-28% of patients [8].

Ou Q. J. analyzed the mechanisms of collateral intrahepatic blood flow and theoretically substantiated the possibility of its normalization without ischemic hepatocyte damage [9]. Kaneko T. et al. revealed intrahepatic collateral blood flow between the right hepatic vein and ligated middle hepatic vein on the 10th postoperative day if the right liver lobe was used for transplantation. Adequate blood flow are confirmed by the fact that the authors questioned the need for additional implantation of the middle hepatic vein into inferior vena cava [19]. These researches created a serious theoretical basis and showed that collaterals can provide adequate venous outflow through the middle hepatic vein including residual right liver lobe after resection of segments VII-VIII in case of ligation of the right hepatic vein and the absence of inferior right hepatic vein. M. Machado et al. [20] performed this surgery in 4 patients and found no early and delayed signs of intrahepatic blood flow impairment. We should also remember that malignant lesion of the right hepatic vein and narrowing of its lumen contribute to the development of compensatory blood flow. Thus, liver resection is carried out in the presence of collaterals de novo. Our study of 16 patients convincingly confirms these facts. This type of resection is valuable to avoid the need for hemihepatectomy or technically difficult replacement of the right hepatic vein. This approach ensures safe preservation of the maximum liver volume, as well as improves the long-term outcomes. Indeed, we ensure the real prerequisites for better resectability in patients with tumor progression eligible for redo liver resection.

The authors declare no conflicts of interest.