Importance of hepatovenous back-perfusion for maintenance of liver viability during the Pringle manoeuvre

Cardiac Metastasis After Curative Treatment of Hepatocellular Carcinoma: Assessment of Risk Factors, Treatment Options, and Prognosis

Hepatocellular carcinoma (HCC) is primary hepatic malignancy with a high incidence of recurrence. The risk of recurrence directly correlates to patient's overall prognosis. Management of advanced HCC involves a combination of surgical resection, locoregional therapy, and systemic treatment. Distant metastases are rare, and intraventricular cardiac metastases are even more infrequent. This brief review details an illustrative case of cardiac metastasis after curative treatment of primary HCC and then summarizes the literature on risk factors, treatment options, and patient prognosis in the setting of distant metastases from HCC. Prognosis of metastasis to the heart is generally poor, and available evidence emphasizes the importance of maintaining regular posttreatment screening for metastases in patients with HCC. Given the variable presentation and high risk of recurrence, it is critical to have individualized multimodality treatment plans.

Interpatient heterogeneity in hepatic microvascular blood flow during vascular inflow occlusion (Pringle manoeuvre)

BACKGROUND

Vascular inflow occlusion (VIO) during liver resections (Pringle manoeuvre) can be applied to reduce blood loss, however may at the same time, give rise to ischemia-reperfusion injury (IRI). The aim of this study was to assess the characteristics of hepatic microvascular perfusion during VIO in patients undergoing major liver resection.

METHODS

Assessment of hepatic microcirculation was performed using a handheld vital microscope (HVM) at the beginning of surgery, end of VIO (20 minutes) and during reperfusion after the termination of VIO. The microcirculatory parameters assessed were: functional capillary density (FCD), microvascular flow index (MFI) and sinusoidal diameter (SinD).

RESULTS

A total of 15 patients underwent VIO; 8 patients showed hepatic microvascular perfusion despite VIO (partial responders) and 7 patients showed complete cessation of hepatic microvascular perfusion (full responders). Functional microvascular parameters and blood flow levels were significantly higher in the partial responders when compared to the full responders during VIO (FCD: 0.84±0.88 vs. 0.00±0.00 mm/mm2, P<0.03, respectively, and MFI: 0.69-0.22 vs. 0.00±0.00, P<0.01, respectively).

CONCLUSIONS

An interpatient heterogeneous response in hepatic microvascular blood flow was observed upon VIO. This may explain why clinical strategies to protect the liver against IRI lacked consistency.

Laser speckle contrast imaging for assessment of liver microcirculation

OBJECTIVE

Laser speckle contrast imaging (LSCI) is a novel technique for microcirculation imaging not previously used in the liver. The aim of the present experimental study was to evaluate the use of LSCI for assessing liver microcirculation.

MATERIALS AND METHODS

In six male Wistar rats, the median liver lobe was exposed through a midline laparotomy. Liver blood perfusion was measured simultaneously with LSCI and sidestream dark-field (SDF) imaging at baseline and during sequential temporary occlusions of the portal vein, hepatic artery, and total blood inflow occlusion. Both the inter-individual variability associated with perfusion sampling area and comparisons in perfusion measurements between both imaging techniques were investigated and validated for the application of LSCI in the liver.

RESULTS

Occlusion of the hepatic artery, portal vein, and total inflow occlusion resulted in a significant decrease in LSCI signal to 74.7±6.4%, 15.0±2.3%, and 10.4±0.5% respectively (p<0.005 vs. baseline). The LSCI perfusion units correlated with sinusoidal blood flow velocity as measured with SDF imaging (Pearson's r=0.94, p<0.001). In a 10 mm diameter region of interest, as measured with LSCI, baseline inter-individual variability measured by the coefficient of variability was 13%.

CONCLUSION

Alterations in LSCI signal during sequential inflow occlusions were in accordance with previously published results on hepatic hemodynamics in the rat and correlated well with our SDF imaging-derived sinusoidal blood flow velocity measurements. We found that LSCI was able to produce reproducible real-time blood perfusion measurements of hepatic microcirculation. Compared to established techniques for liver blood perfusion measurements LSCI holds the advantages of non-contact measurements over large surfaces with a high speed of data acquisition.

Portal triad clamping versus other methods of vascular control in liver resection: a systematic review and meta-analysis

BACKGROUND

Portal triad clamping (PTC) is the most commonly used method of achieving vascular control during liver resection. However, the efficacy and safety of PTC, compared with those of other methods of vascular control, are uncertain.

METHODS

A systematic review was conducted to identify randomized controlled trials (RCTs) comparing PTC with other methods of vascular control during liver resection. Endpoints included in-hospital mortality, need for transfusion, number of complications and length of hospital stay. Meta-analyses were performed using a random-effects model.

RESULTS

Ten RCTs were identified; these included a total of 820 patients. No statistically significant differences between PTC and other forms of vascular control in liver resection were demonstrated.

CONCLUSIONS

There is no evidence, on the basis of this meta-analysis of RCTs, of any difference between PTC and other forms of vascular control in liver resection.

Alleviating the burden of small-for-size graft in right liver living donor liver transplantation through accumulation of experience

The issue of small-for-size graft (SFSG) containing the middle hepatic vein in right liver living donor liver transplantation from 1996 to 2008 (n = 320) was studied. Characteristics of donors, grafts and recipients were comparable between Era I (first 50 cases) and Era II (next 270 cases) except that the median model for end-stage liver disease (MELD) score was higher in Era I (29 vs. 24; p = 0.024). The median graft to standard liver volume ratio (G/SLV) in Era I was 49.0% (range, 32.8-86.2%), versus 49.3% (range, 28.4-89.4%) in Era II (p = 0.498). Hospital mortality rate, the study endpoint, dropped from 16.0% (8/50) in Era I to 2.2% (6/270) in Era II (p = 0.000). Univariate analysis showed that MELD score (p = 0.002), pretransplant hepatorenal syndrome (p = 0.000) and Era I (p = 0.000) were significant in hospital mortality. Logistic regression analysis showed that only Era I (relative risk 9.758; 95% confidence interval, 2.885-33.002; p = 0.000) was significant. In Era I, G/SLV<40% had a relative risk of 7.8 (95% confidence interval, 1.225-49.677; p = 0.030). The hospital mortality rates for G/SLV<40% were 50% (3/6) and 1.9% (1/52) in Era I and II respectively. In conclusion, through accumulation of experience, SFSG became less important as a factor in hospital mortality.

Vascular clamping in liver surgery: physiology, indications and techniques

This article reviews the historical evolution of hepatic vascular clamping and their indications. The anatomic basis for partial and complete vascular clamping will be discussed, as will the rationales of continuous and intermittent vascular clamping.

Specific techniques discussed and described include inflow clamping (Pringle maneuver, extra-hepatic selective clamping and intraglissonian clamping) and outflow clamping (total vascular exclusion, hepatic vascular exclusion with preservation of caval flow). The fundamental role of a low Central Venous Pressure during open and laparoscopic hepatectomy is described, as is the difference in their intra-operative measurements. The biological basis for ischemic preconditioning will be elucidated. Although the potential dangers of vascular clamping and the development of modern coagulation devices question the need for systemic clamping; the pre-operative factors and unforseen intra-operative events that mandate the use of hepatic vascular clamping will be highlighted.

Clinical features of hepatocellular carcinoma developing extrahepatic recurrences after curative resection

BACKGROUND

Few details of the clinical features of hepatocellular carcinoma (HCC) developing extrahepatic recurrence after a curative resection have been published. The purpose of this study was to clarify the clinicopathologic findings of patients with HCC who experienced extrahepatic metastases.

METHODS

Clinicopathologic data were available for 119 patients who underwent an R0 resection for HCC. Twenty-three patients who developed extrahepatic metastases during the follow-up period were compared with the patients who remained free from recurrence for at least 5 years after resection (n = 21) or with only intrahepatic recurrences (n = 75).

RESULTS

Patients with extrahepatic recurrences were more likely to have their tumor macro- or microscopically invading the tumor capsule (P < 0.001) and hepatic vein (P = 0.003), a high AFP concentration (P = 0.014), and advanced TNM stage (P = 0.006) than the other patients. As for treatment-related variables, inflow vessel occlusion during hepatectomy was less frequently associated with extrahepatic recurrences than if it were not performed (P < 0.001). By multivariate analysis, absence of tumor invasion to the capsule (relative risk [RR] = 0.080; P = 0.023) or to the hepatic vein (RR = 0.108; P = 0.014) and a hepatectomy in which inflow vessel occlusions were performed (RR = 0.161; P = 0.004) were selected as independent factors for reducing extrahepatic recurrences after a hepatectomy.

CONCLUSION

In HCC patients, the control of intrahepatic recurrences and extrahepatic recurrences after a hepatectomy is important to improve the prognosis. Inflow occlusion during the hepatectomy may reduce HCC metastases to extrahepatic sites.

Continuous normothermic hemihepatic vascular inflow occlusion over 60 min for hepatectomy in patients with cirrhosis caused by hepatitis B virus

AIM

To evaluate the safety of remnant liver in cirrhotic patients who had undergone irregular hepatectomy with continuous normothermic hemihepatic vascular inflow occlusion for over 60 min.

METHODS

A group of 133 cirrhotic patients who had hepatitis B virus accompanied by hepatocellular carcinoma and had undergone irregular hepatectomy by hemihepatic vascular inflow occlusion was studied. According to the time of hemihepatic vascular inflow occlusion, patients were assigned either to the control group, treatment(60) group, or treatment(90) group. The quantity of blood loss and blood transfusion, routine liver biochemistry and postoperative complications were retrospectively analyzed.

RESULTS

The data showed that there were no significant differences in postoperative complications between the three groups. Compared to the preoperative day, the levels of aspartate transaminase (AST), alanine transaminase (ALT), prothrombin time (PT) and serum bilirubin on postoperative days 1 and 3 were significantly increased in all three groups and the levels of albumin and platelet were significantly decreased on postoperative day 1. Duration of hospital stay and the levels of ALT and AST on postoperative days 1, 3 and 7 were higher in the treatment(90) group than in the control group and treatment(60) group (P < 0.05). However, no significant differences were displayed in the length of hospital stay and the levels of AST, ALT, PT, albumin, platelet count and serum bilirubin on postoperative days 1, 3 and 7 between the control group and the treatment(60) group (P > 0.05).

CONCLUSION

Hemihepatic vascular inflow occlusion over 60 min is a possible method for irregular hepatectomy in patients with cirrhosis caused by the hepatitis B virus. However, caution must be exercised in utilizing this method where the time of vascular occlusion is over 90 min.

Outcome using hemihepatic vascular occlusion versus the pringle maneuver in resections limited to one hepatic section or less

Consensus is lacking concerning how to manage afferent vessels during hepatectomy, particularly as to the Pringle maneuver vs. selective hemihepatic clamping. Data for 81 hepatocellular carcinoma patients with chronic hepatitis or liver cirrhosis whose liver resection was limited to one section or less, including intraoperative data and postoperative liver function data, were analyzed retrospectively to compare two strategies. No significant differences of intraoperative data or postoperative clinical course were seen between the two groups, even in patients with chronic hepatitis or liver cirrhosis whose postoperative deterioration of liver function could be expected to be more than patients with a normal liver. The difference was evident only in serum alanine aminotransferase level on postoperative day 10 (mean +/- SEM, 64.5 +/- 5.1 IU in the Pringle group vs. 51.6 +/- 4.4 IU in the selective clamping group; P < 0.05). During liver resection limited to one section or less, even with underlying chronic hepatitis or cirrhosis, intermittent use of the Pringle maneuver preserved liver function to the same extent as selective clamping.

Ischemic preconditioning for major liver resection under vascular exclusion of the liver preserving the caval flow: a randomized prospective study

BACKGROUND

Two randomized prospective studies suggested that ischemic preconditioning (IP) protects the human liver against ischemia-reperfusion injury after hepatectomy performed under continuous clamping of the portal triad. The primary goal of this study was to determine whether IP protects the human liver against ischemia-reperfusion injury after hepatectomy under continuous vascular exclusion with preservation of the caval flow.

STUDY DESIGN

Sixty patients were randomly divided into two groups: with (n=30; preconditioning group) and without (n=30; control group) IP (10 minutes of portal triad clamping and 10 minutes of reperfusion) before major hepatectomy under vascular exclusion of the liver preserving the caval flow. Serum concentrations of aspartate transferase, alanine transferase, glutathione-S-transferase, and bilirubin and prothrombin time were regularly determined until discharge and at 1 month. Morbidity and mortality were determined in both groups.

RESULTS

Peak postoperative concentrations of aspartate transferase were similar in the groups with and without IP (851 +/- 1,733 IU/L and 427 +/- 166 IU/L respectively, p=0.2). A similar trend toward a higher peak concentration of alanine transferase and glutathione-S-transferase was indeed observed in the preconditioning group compared with the control group. Morbidity and mortality rates and lengths of ICU and hospitalization stays were similar in both groups.

CONCLUSIONS

IP does not improve liver tolerance to ischemia-reperfusion after hepatectomy under vascular exclusion of the liver with preservation of the caval flow. This maneuver does not improve postoperative liver function and does not affect morbidity or mortality rates. The clinical use of IP through 10 minutes of warm ischemia in this technique of hepatectomy is not currently recommended.

Effect of continuous infusion of propofol on its concentration in blood with and without the liver in pigs

In living donor liver transplantation, propofol, an intravenous anesthetic drug, has recently been used in both donors and recipients. Propofol is known to have intra- and extrahepatic metabolic pathways, but the effect of its continuous infusion during a long-term anhepatic state is yet to be determined. Recently, we successfully established a simplified pig model of the complete anhepatic state. In this state, we first evaluated hemodynamic parameters relating to the pharmacokinetics of continuously infused propofol (6 mg.kg(-1) x h(-1)). No significant changes in the concentration of hemoglobin or in hemodynamic parameters other than the heart rate were observed during the anhepatic phase when porpofol was continuously infused at the rate that maintains the state. Blood propofol concentrations in the mixed vein, artery, and portal vein were stable during the anhepatic phase. Finally, we confirmed the pharmacokinetics of continuously infused propofol using orthotropic liver transplantation in miniature pigs. The propofol concentration did not change markedly during the transplant procedure. In conclusion, the pharmacokinetics of continuously infused propofol was almost stable with and without the liver in pigs. Extrahepatic metabolism of propofol might help prevent changes in propofol concentrations.

Liver tissue partial pressure of oxygen and carbon dioxide during partial hepatectomy

BACKGROUND

Data on tissue oxygen partial pressure (PtO2) and carbon dioxide partial pressure (PtCO2) in human liver tissue are limited. We set out to measure changes in liver PtO2 and PtCO2 during changes in ventilation and a 10 min period of ischaemia in patients undergoing liver resection using a multiple sensor (Paratrend Diametrics Medical Ltd, High Wycombe, UK).

METHODS

Liver tissue oxygenation was measured in anaesthetized patients undergoing liver resection using a sensor inserted under the liver capsule. PtO2 and PtCO2 were recorded with FIO2 values of 0.3 and 1.0, at end-tidal carbon dioxide partial pressures of 3.5 and 4.5 kPa and 10 min after the onset of liver ischaemia (Pringle manoeuvre).

RESULTS

Data are expressed as median (interquartile range). Increasing the FIO2 from 0.3 to 1.0 resulted in the PtO2 changing from 4.1 (2.6-5.4) to 4.6 (3.8-5.2) kPa, but this was not significant. During the 10 min period of ischaemia PtCO2 increased significantly (P<0.05) from 6.7 (5.8-7.0) to 11.5 (9.7-15.3) kPa and PtO2 decreased, but not significantly, from 4.3 (3.5-12.0) to 3.3 (0.9-4.1) kPa.

CONCLUSION

PtO2 and PtCO2 were measured directly using a Paratrend sensor in human liver tissue. During anaesthesia, changes in ventilation and liver blood flow caused predictable changes in PtCO2.

Effects of hepatovenous back flow on ischemic- reperfusion injuries in liver resections with the pringle maneuver

BACKGROUND

Experimental findings have demonstrated a beneficial role of retrograde blood flow from hepatic veins that takes place during the Pringle maneuver in liver resections. The cytoprotective effect of hepatovenous back-perfusion has not been evaluated in humans. A randomized prospective study was designed to compare the response of liver cells to ischemic-reperfusion injury during the application of two different ischemic procedures: inflow versus inflow plus outflow vascular occlusion of the liver.

STUDY DESIGN

Forty patients were randomly allocated to undergo liver resection using the continuous Pringle maneuver (n = 20) or inflow plus outflow vascular occlusion of the liver by selective hepatic vascular exclusion (n = 20). Liver function was assessed on postoperative days 1 to 6. Response of liver cells to I/R injury was evaluated by measuring interleukins IL-6 and IL-8 at 3, 12, 24, and 48 hours after reperfusion. Oxidative stress was assessed by measuring malondialdehyde levels.

RESULTS

Both groups were comparable regarding ischemic time, operative time, and extent of liver resection. Patients in whom retrograde blood flow to the liver took place during the Pringle maneuver showed better liver function postoperatively and less severe hepatic I/R injuries compared with those undergoing liver resection using both inflow and outflow vascular occlusion. Oxidative stress was significantly lower in the Pringle maneuver group compared with the inflow plus outflow vascular occlusion group (mean [+/- SD] malondialdehyde 8 +/- 2.1 micromol/L in the Pringle group versus 14.7 +/- 1.8 micromol/L in the selective hepatic vascular exclusion group 30 min after reperfusion, p < 0.01).

CONCLUSIONS

Back perfusion via hepatic veins contributes to attenuation of I/R damage during the Pringle maneuver and should be preferred if possible during liver resection.

Decrease in core liver temperature with 10°C by in situ hypothermic perfusion under total hepatic vascular exclusion reduces liver ischemia and reperfusion injury during partial hepatectomy in pigs

OBJECTIVE

We attempted to assess liver ischemia/reperfusion injury under a mild decrease in core liver temperature of 10 degrees C by in situ hypothermic perfusion during ischemia.

METHODS

Liver ischemia was induced in pigs by total hepatic vascular exclusion with concomitant in situ perfusion with hypothermic (4 degrees C) Ringer-glucose (cold perfused group, core liver temperature maintained at 28 degrees C), with normothermic (38 degrees C) Ringer-glucose (warm perfused group) or without in situ perfusion (control group).

RESULTS

In the cold perfused, warm perfused, and control groups, 24-hour survival was 5/5, 0/5, and 3/5, respectively. Hemodynamic parameters in the cold perfused group remained stable, whereas pigs in both other groups required circulatory support. Plasma AST and interleukin-6 levels were lower in the cold perfused group than in both other groups. Hepatocellular function was best preserved in the cold perfused group as indicated by complete recovery of bile production during reperfusion and no loss of indocyanine green clearance capacity. In both other groups, bile production and indocyanine green clearance capacity were reduced significantly. The hyaluronic acid uptake capacity of pigs in the cold perfused group or control group did not differ, indicating preserved sinusoidal endothelial cell function. Histopathologic injury scores during reperfusion were significantly lower in the cold perfused group when compared to both other groups.

CONCLUSIONS

A mild decrease in core liver temperature of 10 degrees C by in situ hypothermic liver perfusion during ischemia protects the liver from ischemia/reperfusion injury. This protection appears to be related to cooling of the liver rather than to the washout of blood during perfusion.

Uptake of indocyanine green by hepatocytes under inflow occlusion of the liver

BACKGROUND

It is not clear that hepatic venous backflow actually contributes to hepatic tissue oxygenation under inflow occlusion of the liver. In order to prove that substances delivered via the hepatic vein can be utilized and/or metabolized in hepatocytes during inflow occlusion, hepatic uptake in bile and excretion of indocyanine green (ICG) were investigated in pigs.

MATERIALS AND METHODS

Animals were divided into two groups: an inflow occlusion (IO) group (N = 6) and a total hepatic vascular exclusion (THVE) group (N = 3) using a bypass. One milligram of ICG per kilogram body weight was administered at the beginning of blood flow occlusion, the retention rate in the blood (ICG R) measured, and the ICG in the hepatic tissue measured by near-infrared (NIR) spectroscopy. Furthermore, the ICG concentration was measured in bile excreted by intermittent perfusion of the liver.

RESULTS

ICG R declined with time in both groups; however, ICG R in the IO group decreased much faster than in the THVE group. There were significant differences between the two groups after 30 min of occlusion (P < 0.05). ICG in the hepatic tissue could be detected as a peak at 805 nm 10 min after ICG injection, and the peak became steeper with time. On the other hand, ICG was not detected at all in the hepatic tissue after 180 min in the THVE group. ICG was excreted in the bile after 60 min under IO and increased with time. On the contrary, ICG was not excreted in the bile at all under THVE. There were significant differences between the two groups after 90 min (P < 0.05).

CONCLUSION

These results indicate that ICG can be extracted in hepatocytes and excreted in bile under IO of the liver. Consequently, substances such as oxygen and drugs, which are delivered via the hepatic vein, can be utilized and/or metabolized in hepatocytes under IO.

Tissue oxygen pressure during prolonged ischemia of the liver

BACKGROUND

The potential role of hepatovenous back-perfusion in maintaining organ viability of the inflow-occluded liver has been reported with respect to aspects of tissue perfusion and energy metabolism. In the present study, the physiological differences between liver ischemia induced by portal triad clamping (PTC) and that induced by total hepatic vascular exclusion (THVE) were investigated in a porcine disease model, with special reference to changes in tissue oxygen pressure (PtO(2)) of the liver.

MATERIALS AND METHODS

Twelve female pigs were used for induction of 60 min of normothermic liver ischemia. They were assigned to two groups: a PTC group (n = 6) and a THVE group (n = 6). PtO(2) was measured before, during, and after the ischemic period at two different points in the middle lobe: on the central side close to the hepatovenous confluence and on the peripheral side close to the gallbladder bed.

RESULTS

Although central PtO(2) decreased during ischemia in both groups, PTC group values at 40 and 60 min of ischemia remained significantly higher than THVE group values (60 +/- 28 and 42 +/- 21 mmHg vs 11 +/- 5 and 13 +/- 3 mmHg, respectively; means +/- SD). Peripheral PtO(2) in the PTC group during ischemia was low in comparison to corresponding central PtO(2) values.

CONCLUSION

Oxygen supply to the tissue via hepatovenous reflux may contribute to maintaining organ viability under prolonged inflow occlusion of the liver.

Liver hematoma and rupture in pregnancy

Liver hematoma and rupture is a rare but devastating complication of pregnancy. The majority of cases have been associated with severe preeclampsia, but unlike typical preeclampsia, it is a disease of older, multiparous patients. Although there are predictable findings on liver pathology, the underlying pathophysiology is poorly understood. Early recognition and prompt surgical intervention are crucial to reduce the high fetal and maternal mortality rate associated with this disease.