Disruption of the Middle Hepatic Vein is not Crucial for Liver Regeneration of the Remnant Liver After Right Hemihepatectomy for Hepatic Tumors

Influence of middle hepatic vein resection during right or left hepatectomy on post hepatectomy outcomes

Backgrounds/Aims

Middle hepatic vein (MHV) is usually preserved as a part of the right or left hepatectomy in order preserve the venous outflow of remnant liver. The aim of this study was to evaluate if resection of MHV could influence post-resection outcomes of standard right or left hepatectomy.

Methods

Patients who underwent standard right or left hepatectomy between January 2015 and December 2019 were included. Anatomical remnant liver volumes were measured retrospectively using the Hermes workstation (Hermes Medical Solutions AB, Stockholm, Sweden). Uni- and multi-variate analyses were performed to assess the difference in outcomes of those with preservation of MHV and those without preservation.

Results

A total of 144 patients were included. Right hepatectomy was performed for 114 (79.2%) and left hepatectomy was performed for 30 (20.8%) patients. MHV was resected for 13 (9.0%) in addition to the standard right or left hepatectomy. Median remnant liver volume was significantly higher in the MHV resected group (p < 0.01). There was no significant difference in serum level of bilirubin, international normalized ratio, alanine aminotransferase, creatinine on postoperative day 1, 3, 5, or 10, ≥ grade IIIa complications (p = 0.44), or 90-day mortality (p = 0.41). On multivariable analysis, resection of the MHV did not influence the incidence of post hepatectomy liver failure (p = 0.52).

Conclusions

Resection of the MHV at standard right or left hepatectomy did not have a negative impact on postoperative outcomes of patients with adequate remnant liver volume.

Volumetric and Functional Regeneration of Remnant Liver after Hepatectomy

BACKGROUND

Post-hepatectomy liver regeneration is of great interest to liver surgeons, and understanding the process of regeneration could contribute to increasing the safety of hepatectomies and improving prognoses.

METHODS

Five hundred thirty-eight patients who underwent hepatectomy were retrospectively analyzed. Postoperative outcomes were evaluated, with a focus on the effects of portal vein resection and resected liver volume on remnant liver regeneration in patients with liver tumors. Remnant liver volumes (RLVs) and laboratory data were measured postoperatively using multidetector computed tomography on day 7 and months 1, 2, 5, 12, and 24 after the operation.

RESULTS

Liver regeneration speed peaked at 1 week postoperatively and gradually decreased. Regeneration with large resections was longer than that with small resections, with the remnant liver regeneration rate being significantly lower in the former at all time points. Remnant liver regeneration plateaued around 5 months postoperatively, when regeneration is almost complete. Up to 1 month postoperatively, laboratory data were significantly worse when more portal veins was resected. After 2 months postoperatively, these data recovered to near normal levels.

CONCLUSION

The speed and rate of remnant liver regeneration primarily showed a strong correlation with the number of resected portal veins and the amount of removed liver parenchyma. The larger the resection ratio, the longer it took the liver to regenerate. We confirmed that recovery of the liver's functional aspects accompanies recovery of the RLV.

Polyhedral Fenestration Technique Used for Combined Partial Hepatectomy and Cyst Fenestration for Polycystic Liver Disease: A Small Case Series

Objective:

To assess the safety and efficacy of “polyhedral fenestration technique” (PFT), which we newly developed, in combined hepatectomy and cyst fenestration (CHCF) for symptomatic polycystic liver disease (PLD).

Summary of background data:

CHCF for PLD has been reportedly less efficacious for its invasiveness because 50% to 70% patients suffered recurrent symptoms after CHCF.

Methods:

Patient characteristics, intra- and early postoperative variables were compared between 5 PLD patients undergoing CHCF performed with PFT (PLD group) and 95 patients with diseases other than PLD receiving hepatectomy without biliary reconstruction during the same period (Control group) to assess safety of PFT. Chronological changes in total liver volume (TLV) measured by computed tomography (CT) volumetry as well as recurrent symptoms after CHCF were investigated to assess long-term outcomes.

Results:

Although ≧ Clavien-Dindo grade 2 complications were more common in the PLD group than in the Control group (PLD vs Control, 5/5[100%] vs 27/95[28%], p=0.004), patient characteristics, intra-, and early postoperative variables, including ≧ Clavien-Dindo grade 3 complications, were comparable among the 2 groups. Postoperative observational period of the 5 PLD patients ranged 30 to 88 months with a median of 63. CT volumetry revealed that TLV continued to reduce up to 1 year after surgery and thereafter retained less than 0.5 times of preoperative TLV in all patients. Recurrent liver enlargement or recurrent symptoms were not observed in any of the 5 PLD patients.

Conclusions:

Although our case series was very small, newly-developed PFT in CHCF for PLD yielded acceptable safety and excellent long-term outcomes.

Effect of Portal Vein Ligation Plus Venous Congestion on Liver Regeneration in Rats

INTRODUCTION AND AIM

We developed a rat model of portal vein ligation (PVL) with venous congestion (PVL+C) to investigate beneficial effect PVL plus congestion for regeneration of intact liver segments.

MATERIALS AND METHODS

In the PVL group, portal vein branches were ligated except the caudate lobe (CL). In the PVL + C group, the left lateral hepatic vein was ligated in addition to PVL. Chronological changes in the following variables were compared among the groups: CL weight to body weight ratio (CL/BW), embolized liver weight to body weight ratio (EL/BW), histological findings of the embolized/non-embolized liver, and expression of several mediators that affect liver regeneration in the non-embolized liver.

RESULTS

Weight regeneration of CL continued up to postoperative day (POD)7 in PVL + C, but terminated at POD2 in PVL. CL/BW at POD7 was significantly higher in PVL + C than in PVL (2.41 ± 0.33% vs. 1.22 ± 0.18%, P < 0.01). In contrast, EL/BW continued to decrease up to POD7 in PVL + C but reached nadir at POD2 in PVL. Furthermore, EL/BW at POD7 was significantly smaller in PVL + C than in PVL (0.35 ± 0.03% vs. 0.67 ± 0.08%, P < 0.01). Histologically-proven injury in the embolized liver was more severe in PVL + C than in PVL. Expression of Ki-67, IL-6, TNF -a, and HGF were greater and/or more prolonged in PVL + C than in PVL.

CONCLUSIONS

Our rat model of PVL + C was considered useful for investigating the beneficial effect of congestion in addition to PVC. PVL + C caused increased devastation of the embolized liver, and higher and more prolonged expression of factors promoting liver regeneration in the non-embolized liver than in PVL.

An extended dysfunctional area in the congestive area of the remnant liver after hemi-hepatectomy with middle hepatic vein resection for liver cancers evaluated on the gadoxetic acid disodium-enhanced magnetic resonance imaging

BACKGROUND

The aim of the present study was to evaluate the liver function in the congestive area of the remnant liver after hemi-hepatectomy with middle hepatic vein (MHV) resection for liver cancers.

METHODS

From November 2009 through December 2012, 18 patients underwent hemi-hepatectomy including the MHV for liver cancers. Post-hepatectomy, the volume of the congestive area, which appeared as a hyper-intense area on T2-weighted images and dysfunctional area, which appeared as a low intensity area on hepatobiliary phase images in the remnant liver was evaluated in all patients by gadoxetic acid disodium-enhanced magnetic resonance imaging.

RESULTS

Fifteen of 18 patients showed a congestive area, and 16 of 18 patients showed a dysfunctional area in the remnant liver. The dysfunctional rate (median 11%) was significantly larger than the congestive rate (median 5%, P = 0.0004). The dysfunctional rate was associated with tumor invasion to the root of the MHV, and no tumor invasion to the root of the MHV was identified as a significant predictor of a larger dysfunctional area (odds ratio 25.888, P = 0.0267) on multivariate analysis.

CONCLUSION

Hemi-hepatectomy with MHV resection for liver cancers should be performed considering the dysfunctional area in the remnant liver, which is associated with tumor invasion to the root of the MHV.

Median liver lobe of woodchuck as a model to study hepatic outflow obstruction: a pilot study

BACKGROUND

Hepatic vein outflow obstruction represents an important clinical problem in living-liver transplantation. An animal model is required to study the influence of outflow obstruction on the intrahepatic regulation of liver perfusion and the subsequent effects on liver injury and recovery during liver regeneration. The size of woodchucks enables the use of standard clinical imaging procedures.

AIM

This study aims at describing hepatic vascular and territorial anatomy of the woodchuck liver based on a virtual three-dimensional (3D) visualization of the hepatic vascular tree.

METHODS

Woodchucks (n=6) were subjected to an all-in-one computed tomography (CT) after contrasting the vascular and the biliary tree. CT-images were used for 3D-reconstruction of hepatic and portal veins and calculation of the corresponding portal and hepatic vein territories and their respective volume using hepavision (MeVisLab). A virtual resection was performed following the Cantlie-line and territories at risk were calculated.

RESULTS

The median lobe of the woodchuck liver has a similar vascular supply and drainage as the human liver with two portal (right and left median portal vein) and three hepatic veins (left, middle and right median hepatic vein). The corresponding portal and hepatic vein subterritories are of a similar relative size compared with the human liver. Virtual splitting of the median lobe of the woodchuck liver revealed areas at risk of focal outflow obstruction, as observed clinically.

CONCLUSION

The median liver lobe of the woodchuck represents, to a small extent, the hepatic vascular anatomy of the human liver and is therefore a suitable potential model to correlate repeated imaging of impaired liver perfusion with histomorphological findings of liver damage and regeneration.

Comparison between the minimum margin defined on preoperative imaging and the final surgical margin after hepatectomy for cancer: how to manage it?

BACKGROUND

The liver surgeon's decision to operate is based on imaging studies. However, no clear practical guidelines are available enabling surgeons to safely predict tumor-free margins after a partial hepatectomy. The aim of this retrospective study is to provide surgeons with simple and easily applicable practical guidelines.

METHODS

We retrospectively stringently selected 42 anatomical right or left hepatectomies whose main characteristic was to pass along the median hepatic vein, which was preserved. This vein is an easily visualized anatomical landmark on preoperative imaging and is never transgressed by the surgeon. We compared the minimum distance between the tumor and this vein measured on preoperative imaging, and the minimum tumor-free excision margin measured on the specimen by the pathologist.

RESULTS

The median tumor-free excision margin was 5 mm at pathological analysis, significantly different (P < .0001) from the tumor-free margin measured on preoperative imaging (15 mm). The mean difference between these two measurements was 10 +/- 4 mm (median, 9 mm). This difference was partly the result of the transection and partly the result of technical deviations in relation to the ideal resection line.

CONCLUSIONS

The liver surgeon must consider that roughly a 5 to 8 mm tumor-free margin will disappear during hepatectomy when comparing measurements on the basis of preoperative imaging versus tumor-free specimen margins. If the histologically assessed minimum 2-mm tumor-free margin is added, the surgeon must plan to have a 7 to 10 mm tumor-free margin on preoperative imaging. However, few technical solutions exist that would enable the surgeon to increase the safety margin in borderline cases.