Arterial Blood Supply of Liver Segment IV and Its Possible Surgical Consequences

Anatomical Variations of the Cystic Artery and Laparoscopic Cholecystectomy: A Persisting Surgical Challenge

Although elective laparoscopic cholecystectomy is a common surgical procedure, it can become challenging due to multiple variants of the anatomy of both cystic artery and cystic bile duct. A 52-year-old male with a history of symptomatic cholelithiasis underwent elective laparoscopic cholecystectomy. During preparation of the Calot's triangle in order to achieve the "critical view of safety", an uncommon variation of the arterial anatomy was detected. The cystic artery was found to be originating from a robust middle hepatic artery instead of the right hepatic artery. The retrograde manner of cholecystectomy helped the visualization and protection of the middle hepatic artery. This anatomic finding was confirmed per CT done postoperatively. This case constitutes a rare arterial variation, in which the cystic artery arises from the middle hepatic artery, the artery that supplies the hepatic segment IV, which itself constituted a rare variation, since it arose from the anterior branch of the right hepatic artery. This artery could be falsely ligated instead of the real cystic artery. Certain techniques can be used to enhance the surgeon's ability to distinguish and safely ligate the proper entities. Anatomic knowledge of the possible variations of arterial and bile vessels is crucial for intraoperative recognition. Dissection of the Calot's triangle and reassurance of the "critical view of safety" are mandatory dissection techniques during laparoscopic cholecystectomy. Additionally, the retrograde manner of cholecystectomy can be of significant help in case of unclear anatomy in order to avoid ligation of uncertain entities during dissection.

The Importance of Segment 4 Anatomy on Outcomes Following Living Donor Left Lateral Segmentectomy

BACKGROUND

During left lateral section (LLS) resection for live liver donation, the vascular inflow and the bile drainage of segment 4 (S4) are compromised. We investigated the long-term changes of S4 after donation and their potential prognostic impact on living liver donors.

MATERIALS AND METHODS

This was a retrospective analysis of 42 consecutive left lateral (LLS, S2/3) liver resections for living donation.

RESULTS

There were 25 female and 17 male donors. Median age was 33 y and median body mass index was 26. Median LLS, S2/3, volume was 262 cc, and median sS4 volume was 160 cc. Complications were encountered in three donors (7%). An independent extrahepatic S4 artery (S4A) (with a proximal left heptic artery or a right hepatic artery origin) was identified in 41% of the donors. Ligation of the independent S4A was not associated with the rate of post resection liver dysfunction, complications, or the degree of S4 atrophy. Having a dominant S4 portal triad pedicle feeding the right anterior sectors, segment 5/8, of the liver was associated with increased parenchymal damage as evidenced by a higher peak of alanine aminotransferase but was not associated with postoperative complications. The median degree of atrophy of S4 at 1 y post donation as noted on imaging was 66%. The presence of a dominant S4 portal triad pedicle and the peak alanine aminotransferase early postoperatively were both predictors of the degree of S4 atrophy post donation.

CONCLUSIONS

The presence of an independent S4A or dominant S4 portal triad pedicle feeding the liver right anterior sectors, segment 5/8, should not be a contraindication for left lateral segment living donation.

Topological approach of liver segmentation based on 3D visualization technology in surgical planning for split liver transplantation

BACKGROUND

Split liver transplantation (SLT) is a complex procedure. The left-lateral and right tri-segment splits are the most common surgical approaches and are based on the Couinaud liver segmentation theory. Notably, the liver surface following right tri-segment splits may exhibit different degrees of ischemic changes related to the destruction of the local portal vein blood flow topology. There is currently no consensus on preoperative evaluation and predictive strategy for hepatic segmental necrosis after SLT.

AIM

To investigate the application of the topological approach in liver segmentation based on 3D visualization technology in the surgical planning of SLT.

METHODS

Clinical data of 10 recipients and 5 donors who underwent SLT at Shenzhen Third People’s Hospital from January 2020 to January 2021 were retrospectively analyzed. Before surgery, all the donors were subjected to 3D modeling and evaluation. Based on the 3D-reconstructed models, the liver splitting procedure was simulated using the liver segmentation system described by Couinaud and a blood flow topology liver segmentation (BFTLS) method. In addition, the volume of the liver was also quantified. Statistical indexes mainly included the hepatic vasculature and expected volume of split grafts evaluated by 3D models, the actual liver volume, and the ischemia state of the hepatic segments during the actual surgery.

RESULTS

Among the 5 cases of split liver surgery, the liver was split into a left-lateral segment and right tri-segment in 4 cases, while 1 case was split using the left and right half liver splitting. All operations were successfully implemented according to the preoperative plan. According to Couinaud liver segmentation system and BFTLS methods, the volume of the left lateral segment was 359.00 ± 101.57 mL and 367.75 ± 99.73 mL, respectively, while that measured during the actual surgery was 397.50 ± 37.97 mL. The volume of segment IV (the portion of ischemic liver lobes) allocated to the right tri-segment was 136.31 ± 86.10 mL, as determined using the topological approach to liver segmentation. However, during the actual surgical intervention, ischemia of the right tri-segment section was observed in 4 cases, including 1 case of necrosis and bile leakage, with an ischemic liver volume of 238.7 mL.

CONCLUSION

3D visualization technology can guide the preoperative planning of SLT and improve accuracy during the intervention. The simulated operation based on 3D visualization of blood flow topology may be useful to predict the degree of ischemia in the liver segment and provide a reference for determining whether the ischemic liver tissue should be removed during the surgery.

Left Anterior Sectorectomy: An Alternative to Left Hepatectomy for Tumors Invading the Distal Part of the Left Portal Vein

Background: Liver tumors invading the distal part of the umbilical portion of the left portal vein usually require left hepatectomy. The recent introduction of the concept of left anterior sector, an independent anatomo-functional unit including the anterior portion of the left liver and supplied by the distal part of the umbilical portion of the left portal vein, could represent the rational for an alternative surgical approach. The aim of this study was to introduce the novel surgical procedure of ultrasound-guided left anterior sectorectomy. Methods: Among 92 consecutive patients who underwent hepatectomy, 3 patients with tumor invading the distal part of the umbilical portion of the left portal (two with colorectal liver metastases and one with neuroendocrine tumor liver metastases) underwent left anterior sectorectomy alone or in association with liver multiple metastasectomies. Results: Mean operation time was 393 min; post-operative morbidity and mortality were not observed. After a mean FU of 23 months (range 19–28), no local recurrence occurred. Conclusions: In presence of tumors invading the distal part of the umbilical portion of the left portal, left anterior sectorectomy could be considered as an anatomic radical surgical option that is safe but more conservative than a left hepatectomy.

Associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) in colorectal liver metastases: review of the literature

The liver is considered as one of the most common sites of metastasis and a key determining factor of survival in patients with isolated colorectal liver metastasis (CRLM). For longer survival of patients, surgical resection is the only available option. Especially in CRLM bilobar patients, to achieve R0 resection, maintaining an adequate volume of the future liver remnant (FLR) is the main technical challenge to avoid post-hepatectomy liver failure (PHLF). As standard procedures in the treatment of patients with severe metastatic liver disease, techniques such as portal vein embolization/portal vein ligation (PVE/PVL) accompanied by two-stage hepatectomy (TSH) have been introduced. These methods, however, have drawbacks depending on the severity of the disease and the capacity of the patient to expand the liver remnant. Eventually, implementation of the novel ALPPS technique ignited excitement among the community of hepatobiliary surgeons because ALPPS challenged the idea of unrespectability and extended the limit of liver surgery and it was reported that FLR hypertrophy of up to 80% was induced in a shorter time than PVL or PVE. Nonetheless, ALPPS techniques caused serious concerns due to the associated high morbidity and mortality levels of up to 40% and 15% respectively, and PHLF and bile leak are critical morbidity- and mortality-related factors. Carefully establishing the associated risk factors of ALPPS has opened up a new dimension in the field of ALPPS technique for improved surgical outcome by carefully choosing patients. The benefit of ALPPS technique is enhanced when performed for young patients with very borderline remnant volume. Adopting ALPPS technical modifications such as middle hepatic vein preservation, surgical management of the hepatoduodenal ligament, the anterior approach and partial ALPPS may lead to the improvement of ALPPS surgical performance. Research findings to validate the translatability of ALPPS’ theoretical advantages into real survival benefits are scarce.

A Novel Surgical Technique to Assure Donor and Recipient Safety: Pyloric to Segment 4 Arterial Reconstruction

Background.

Strategies to extend the pool of organs include and promote the use of segmental liver grafts. While performing a living donor left lateral segment (LLS) liver transplant and in split procedures, the hepatic artery´s division becomes critical when a dominant segment 4 artery (S4A) emerges from the left hepatic artery (LHA). We aim to describe a novel technique that consists of performing microsurgical reconstruction from the pyloric artery (PA) to S4A.

Case Reports.

A 45-y-old living donor was evaluated to use his LLS as a graft for a pediatric recipient. During the procedure, a dominant S4A born from the LHA was dissected. To obtain an appropriate LHA length and diameter for the recipient, it was necessary to transect it. An extended right lobe split graft was used in a 61-y-old patient. The S4A born from LHA had to be sectioned during the split procedure. In both cases, segment 4 remained incompletely perfused. The PA was dissected with enough length to be rotated, to perform a microsurgical anastomosis to the S4A, recovering parenchyma’s color and Doppler signal while vascular permeability was demonstrated using CT scan. There was no biliary or cut surface complication.

Conclusions.

PA to S4A reconstruction is a simple and novel technique that can be used for LLS and extended right lobe split graft and might contribute to increase donor selection and reduce living donor and recipient S4A-related complications.

Application of pediatric donors in split liver transplantation: Is there an age limit?

The experience of using pediatric donors in split liver transplant is exceedingly rare. We aim to investigate the outcomes of recipients receiving split pediatric grafts. Sixteen pediatric recipients receiving split liver grafts from 8 pediatric donors < 7 years were enrolled. The donor and recipient characteristics, perioperative course, postoperative complications, and graft and recipient survival rates were evaluated. The mean follow-up time was 8.0 ± 2.3 months. The graft and recipient survival rates were 100%. The liver function remained in the normal range at the end of the follow-up time in all recipients. No life-threatening complications were seen in these recipients, and the only surgery-related complication was portal vein stenosis in 1 recipient. Cytomegalovirus infection was the most common complication (62.5%). The transaminase level was significant higher in extended right lobe recipients in the early postoperative days, but the difference vanished at the end of first week; postoperative complications and graft and recipient survival rates did not differ between left and right graft recipients. Notably, the youngest split donor graft (2.7 years old) was associated with ideal recipient outcomes. Split liver transplant using well-selected pediatric donors is a promising strategy to expand pediatric donor source in well-matched recipients.

[Surgical anatomy of liver segment iv and its importance in hepatobiliary surgery]

The purpose of this article was to describe clinical anatomy of liver segment IV and determine its significance in liver resection surgery and within integrated approach in the treatment of malignancies of this area.

Current status of associating liver partition with portal vein ligation for staged hepatectomy: Comparison with two-stage hepatectomy and strategies for better outcomes

Since its introduction in 2012, associating liver partition with portal vein ligation for staged hepatectomy (ALPPS) has significantly expanded the pool of candidates for liver resection. It offers patients with insufficient liver function a chance of a cure. ALPPS is most controversial when its high morbidity and mortality is concerned. Operative mortality is usually a result of post-hepatectomy liver failure and can be minimized with careful patient selection. Elderly patients have limited reserve for tolerating the demanding operation. Patients with colorectal liver metastasis have normal liver and are ideal candidates. ALPPS for cholangiocarcinoma is technically challenging and associated with fair outcomes. Patients with hepatocellular carcinoma have chronic liver disease and limited parenchymal hypertrophy. However, in selected patients with limited hepatic fibrosis satisfactory outcomes have been produced. During the inter-stage period, serum bilirubin and creatinine level and presence of surgical complication predict mortality after stage II. Kinetic growth rate and hepatobiliary scintigraphy also guide the decision whether to postpone or omit stage II surgery. The outcomes of ALPPS have been improved by a combination of technical modifications. In patients with challenging anatomy, partial ALPPS potentially reduces morbidity, but remnant hypertrophy may compare unfavorably to a complete split. When compared to conventional two-stage hepatectomy with portal vein embolization or portal vein ligation, ALPPS offers a higher resection rate for colorectal liver metastasis without increased morbidity or mortality. While ALPPS has obvious theoretical oncological advantages over two-stage hepatectomy, the long-term outcomes are yet to be determined.

Arterial Blood Supply of Liver Segment IV and Its Possible Surgical Consequences

The risk of ischemia of segment IV after split liver resection is high. This anatomical study was done to identify the arterial blood supply and the intrahepatic distribution of liver segment IV. The anatomy of segment IV was studied in 29 livers from adult cadavers. To identify the arterial blood supply of segment IV, water and ink were injected into the various branches of the hepatic artery and the outflow through segment IV and discoloration of the liver parenchyma were observed. In 23 of the 29 livers (79.3%), the arterial perfusion of segment IV was separated by a line drawn from the left side of the inferior vena cava at the top of and lateral to the falciform ligament to the medial point of the gallbladder bed. The area lateral to this line was supplied mainly by the right hepatic artery, and the area medial to it was supplied mainly by the left hepatic artery. In addition to the classification system of Couinaud, we describe here a new division of liver segment IV based on arterial blood supply. These anatomical findings may be useful in defining the resection line for split liver to prevent necrosis of segment IV.