Hepatic Vascular Occlusion Research Articles

Hepatic vascular inflow occlusion enhances tissue destruction during cryoablation of porcine liver 1

Background Local recurrences after cryoablation of liver tumors have been reported at rates from 5% to 44% and can be caused by inadequate coverage of the tumor by the frozen region. Hepatic vascular inflow occlusion may facilitate ablation by enlarging the size of the frozen region and the tissue necrosis induced by freezing. Few studies have documented these effects of inflow occlusion during liver cryoablation. Materials and methods Two cryolesions were induced in the liver of 12 pigs in a standardized set-up. Vascular inflow occlusion was used in six pigs during freezing. Two freeze cycles were performed at each location. Ice-ball volume was estimated by intraoperative magnetic resonance imaging. Cryolesion volume was estimated from histopathologic examination of the lesions 4 days after ablation. Results The median volume of ice-balls produced during inflow occlusion was 107% larger than for ice-balls produced without occlusion ( P < 0.001). The median volume of cryolesions made during inflow occlusion was 195% larger than for cryolesions induced without occlusion ( P < 0.001). The geometry of the ice-balls was more regular if produced during inflow occlusion than if not. The ice-balls produced during the second freeze cycle were 17% and 20% larger than the ice-ball produced during the first freeze for lesions made with ( P = 0.01) and without ( P = 0.03) inflow occlusion. Conclusions Hepatic vascular inflow occlusion enables freezing of larger volumes of liver tissue andincreases the volume of tissue necrosis induced during cryoablation of porcine liver.

Intraoperative contrast-enhanced MR-imaging as predictor of tissue damage during cryoablation of porcine liver.

This study evaluate intraoperative Magnetic Resonance Imaging (MRI) as predictor of tissue damage following cryoablation of porcine liver with and without concomitant hepatic vascular inflow occlusion. Inflow occlusion was used during freezing in 6 of 12 pigs included. The volumes of the procedural ice-balls were estimated from MR images. Immediately after thawing contrast (MnDPDP) enhanced MRI was performed to estimate the volume of the cryolesion. Four days after ablation MRI was repeated of the in-vivo and the ex-vivo liver. Photography was performed of the sliced liver specimens to estimate the volumes of the lesions. The intraoperative volume of the cryolesion as shown by contrast enhanced MRI corresponded well to the ice-ball volume for lesions made without vascular occlusion (difference 0.3 +/- 0.9 cm(3), p = 0.239). For lesions made during occlusion the volume of the intraoperative cryolesion was larger than the corresponding ice-ball (difference 7.5 +/- 3.3 cm(3), p = 0.003). The volume of the cryolesions as estimated from histopathology four days after freezing and contrast enhanced MRI immediately after freezing corresponded well for lesions made with (difference -2.6 +/- 4.5 cm(3), p = 0.110) and without vascular occlusion (difference -0.5 +/- 2.3 cm(3), p = 0.695). Intraoperative MnDPDP-enhanced MRI of the cryolesion is predictive of the tissue damage induced during cryoablation of porcine liver. The procedural ice-ball is not, if induced during inflow occlusion.

Radiofrequency tissue ablation: effect of hepatic blood flow occlusion on thermal injuries produced in cirrhotic livers.

Radiofrequency thermal ablation has been used as a treatment for several types of hepatic malignancies. Many of these lesions exist in the presence of cirrhosis. Limitations exist to the size of the ablations and, subsequently, the efficacy of treatment. Hepatic vascular inflow occlusion has been advocated as an adjunctive measure to increase the efficacy of the ablation. We present a model in the human cirrhotic liver that demonstrates the advantage of blood flow occlusion during radiofrequency ablation. Five patients with advanced endstage liver disease scheduled to have orthotopic liver transplantation were enrolled in this study. After laparotomy and before hepatectomy, radiofrequency ablation was performed without and with hepatic blood flow occlusion. After hepatectomy, the liver was sectioned, the area of ablation was measured in three dimensions, and the volume of ablation calculated. Three of the patients had had previously placed transjugular intrahepatic portosystemic shunt. The mean volume of the ablation without blood flow occlusion was 22.5 +/- 7.4 cm(3) and that with blood flow occlusion was 48.4 +/- 24.0 cm(3) (P =.05). Ablation area is increased significantly with hepatic blood flow occlusion in the human cirrhotic liver. This result may have application in the treatment of larger (>3 cm) hepatic malignancies.

Liver trauma: experience in 348 cases.

Liver trauma, the main cause of death in patients suffering abdominal injury, remains an unresolved problem, especially in its most severe forms. The objective of this study was to probe effective surgical procedures and improve the outcome for patients with severe hepatic injury. A retrospective study of 348 patients with hepatic trauma seen in our institution during the past 12 years was carried out. Of these 348 patients, 259 (74.4%) underwent surgery. To manage severe liver trauma (American Association for the Surgery of Trauma grade III to grade V), procedures such as packing of the laceration with omentum, hepatectomy or direct control of bleeding vessels within the liver substance by means of the Pringle maneuver, selective hepatic artery ligation, retrohepatic caval repair with total hepatic vascular occlusion, and perihepatic packing were selected and combined based on the specific injury. In the 259 patients treated operatively, the survival rate was 86.9% (225/259); and 15 of 40 with retrohepatic venous injury (RHVI) were cured with the maximum blood transfusion of 60 units. In 42 patients treated by perihepatic packing, the bleeding was stopped in 20 of 25 (80%) with RHVI and in 14 of 17 (82%) without such injury ( p > 0.75). The percentage of failure of nonoperative management was 17.2% (17/99); and it was 46.7% (14/30) in patients with grade III-V injury. Death occurred in 3 (50%) of 6 failures of grade IV-V injury. The overall mortality rate was 11.8% (41/348), and 51% of the deaths were due to exsanguination. The results suggest that severe hepatic injuries, especially grade IV-V injuries, usually require surgical intervention; reasonable surgical procedures based on classification of liver trauma and combined application of techniques can increase the survival rate; and perihepatic packing is effective in dealing with RHVI.

Radiofrequency ablation of the porcine liver with complete hepatic vascular occlusion.

We studied the effects of radiofrequency ablation, relative to hepatic blood flow, on the volume and shape of the resulting tissue necrosis. The extent of necrosis is directly proportional to the size of the electrode and inversely related to blood flow, which dissipates the heat generated. Two areas of necrosis were created in each of eight porcine livers, which were assigned to four groups according to blood flow occlusion: no occlusion, occlusion of the hepatic artery and portal vein, occlusion of the hepatic veins, and complete hepatic vascular occlusion. After 25 minutes of liver reperfusion, the animals were euthanized, and the livers were examined. Complete vascular occlusion resulted in the greatest area of necrosis (28.6 +/- 3.4 cm(3)), followed by occlusion of the hepatic artery and portal vein (19.2 +/- 5.9 cm(3)), occlusion of hepatic veins (14.4 +/- 2.6 cm(3)), and no occlusion (4.9 +/- 1.5 cm(3)). The volume of the necrotic areas created during complete vascular occlusion were significantly greater than those created with no occlusion, as well as those created with only the hepatic artery and portal vein occluded (P <.05). Complete vascular occlusion, combined with radiofrequency ablation, increases the volume of necrosis and creates a more spherical ablative area.

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

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

Changes in tissue oxygenation of the porcine liver measured by near-infrared spectroscopy.

Near-infrared spectroscopy (NIRS) is a novel method for the measurement of tissue oxygenation and may have a role in monitoring liver oxygenation and viability. The aim of this study is to validate the application of NIRS for monitoring hepatic tissue oxygenation. Large Landrace pigs (n = 12) underwent laparotomy and liver exposure. Total hepatic blood flow (THBF) was measured by the Transonic Medical Flowmeter system. NIRS probes were placed on the liver surface to continuously record changes in hepatic tissue oxyhemoglobin (HbO2), deoxyhemoglobin (Hb), and the reduction-oxidation state of cytochrome oxidase (Cyt Ox). Reduction of hepatic tissue oxygenation was achieved by hepatic vascular inflow occlusion (n = 6) or reduction of inspired oxygen (FIO2; n = 6). The THBF changes correlated significantly with hepatic HbO2 (r = 0.84; P <.001) and Cyt Ox (r = 0.88; P <.001). With reduction of FIO2, a significant correlation was found between arterial oxygen saturation and hepatic HbO2 and Hb (r = 0.99 and r = -0.99, respectively; P <.0001). NIRS measurement of liver parenchymal oxygenation correlates well with changes in liver blood flow and arterial oxygenation.

Prolonged continuous or intermittent vascular inflow occlusion during hemihepatectomy in pigs.

To assess ischemia and reperfusion (I/R) injury in a hemihepatectomy model in pigs after prolonged continuous or intermittent vascular inflow occlusion in the liver. Massive intraoperative blood loss during liver resections can be prevented by temporary vascular inflow occlusion, consequently leading to ischemia and reperfusion injury in the remnant liver. Previously, in a pig liver resection model in which only limited I/R injury was induced during brief (90 min) vascular inflow occlusion, the authors demonstrated reduced I/R injury after continuous (CNT) occlusion, compared to intermittent (INT). This liver resection study on pigs was undertaken to assess I/R injury after prolonged (120 min) CNT or INT occlusion. In pigs (37.0 +/- 1.5 kg), liver ischemia during 2 hours was CNT (n = 6) or INT (n = 6) (eight subsequent periods of 12 min ischemia and 3 min recirculation), followed by 6 hours of reperfusion. A left hemihepatectomy (45.5% +/- 1.4%) was performed within the first 12 minutes of ischemia. No hepatic pedicle clamping or liver resection was performed in control experiments (n = 6). Microvascular damage was assessed by hyaluronic acid (HA) uptake capacity of the liver (parameter of early sinusoidal endothelial cell damage) and restoration of intrahepatic tissue pO2 during reperfusion. Hepatocellular damage was tested by plasma concentrations of aspartate aminotransferase (AST), alanine aminotransferase, and lactate dehydrogenase (LDH). Hyaluronic acid uptake after 6 hours of reperfusion, compared to preischemic uptake, was unaltered in the control group, but was significantly reduced in both resection groups. However, more HA was taken up after INT occlusion, compared to CNT (60.4% +/- 5.6% and 39.5% +/- 3.7%, respectively; ANOVA: p = 0.001). Intrahepatic tissue pO2 distribution after 6 hours of reperfusion more closely returned to preischemic configuration in the INT group than in the CNT group, indicating reduced microcirculatory disturbances after INT occlusion. Release of AST and LDH after 6 hours of reperfusion was significantly increased in both CNT and INT groups. Lower AST levels, however, were found after INT occlusion than after CNT occlusion (267.0 +/- 74.7 U/l and 603.3 +/- 132.4 U/l, respectively; p = 0.06). Intermittent hepatic vascular inflow occlusion during prolonged liver ischemia in pigs resulted in less microcirculatory and hepatocellular injury, compared to continuous occlusion. Intermittent clamping is preferable when prolonged periods of vascular inflow occlusion are applied during liver resections.

Hepatectomy with microwave tissue coagulator: with special reference to combination of hemi-or total hepatic vascular occulusion

We investigated the advantage to hepatectomy with combination of microwave tissue coagulator (MTC) and hepatic vascular occulusion. Fourty one consecutive patients undergoing hepatic resection by our method were evaluated with references to comparison of reported hepatectomized cases using MTC without hepatic vascular clamp. We performed microwave coagulation only along the intended liver surface resection line and no more, then urtrasonically guided liver resection initiated along with coagulated line by forceps frature method with intermittent vasucular occulusion. The efficacy of MTC in hepatectomy, as many authors reported, was reduction in blood loss during operation without vasucular clamp i.e. warm ischemia of the liver which regarded as contraindicates to dameged liver. This 41 consecutive liver resections consisted of partial (Hr0 : 13), subsegmental (Hr1 : 13), segmental (Hr1 : 8), lobar (Hr2 : 1), extended lobar (Hr2 + : 1). In this study, the cases of postoprerative intrperitoneal infection, bile lekage, hemorrhage, was one respectively (2.4%) and ascites were 2 cases (4.9%), pleural effusion were 3 cases (7.3%). The average amount of blood loss was 763 ± 110 ml and average volume of resected liver was 194 ± 209g. The post operative laboratory data related to liver function changed within accepatable range reasonable for operative magnitude. Intraperative blood loss, postoperative complications' rates, postoperarive clinical courses were all not only diferent with using MTC without hepatic clamp but also more favorable results. No complications attributable to combined usage of MTC and vascular clamp were emerged.We concluded that combination of MTC and hepatic vascular occlusion was very useful for safer hepatic resection.

Evaluation of serum uric acid changes in different forms of hepatic vascular inflow occlusion in human liver surgeries

Uric acid values in serum have been analyzed as one of the markers to predict cellular damage due to ischemia reperfusion injury in the field of organ transplantation. The present study was conducted to confirm that uric acid values in serum could be an efficient marker of ischemic injury of liver parenchyma following hepatic vascular occlusion in human liver surgery. The changes in serum uric acid values were analyzed at fixed intervals during different liver surgeries. Significant increases in serum uric acid values were observed in patients who received the Pringle's maneuver in which hepatic vascular inflow was manipulated with a repetition of 15 min occlusion and 5 min perfusion, whereas almost no changes in uric acid values were found in both groups of patients who received the hemilobal occlusion of the Glisson's triad in which the right or left vessels were manipulated with a repetition of 30 min occlusion and 5 min perfusion and the “control method” in which the hepatic vessels of the lesion side were previously cut before liver resection. Uric acid values in serum increased in patients of Pringle's maneuver compared to those of the hemilobal occlusion of the Glisson's triad and the control method though these procedures were used in larger hepatectomies rather than Pringle's maneuver. The results indicated that serum uric acid values do not always reflect the severity of ischemia of the liver parenchyma but reflect intestinal congestion because marked intestinal congestion was observed in patients of Pringle's maneuver but not in patients of the hemilobal occlusion of the Glisson's triad and the control method. The evaluation of the severity of the ischemic injury of the liver should be done with caution when uric acid is used as a marker in human liver surgery.

Efficacy of hypothermic perfusion using University of Wisconsin solution in extended hepatectomy with hepatic inflow occlusion in a canine model.

This study was designed to elucidate the efficacy of University of Wisconsin (UW) solution for preventing liver injury, when used as a hypothermic perfusate infused into the systemic circulation during extended hepatectomy with hepatic inflow occlusion. Adult mongrel dogs (9.5-17.5 kg, n = 14) were subjected to 75% hepatectomy under 60 min hepatic inflow occlusion. The animals were divided into two groups. The UW group (n = 7) underwent hypothermic perfusion using 4 degrees C UW solution (core temperature of the liver: 12.3 +/- 0.2 degrees C). The control group designated as the Ringer's lactate (LR) group (n = 7) underwent hypothermic perfusion using 4 degrees C LR solution. The perfusate was introduced into the systemic circulation via the hepatic vein. Blood from the hepatic vein was sampled, and alanine aminotransferase, purine nucleoside phosphorylase activities and the ammonia concentration were measured. The 7 day survival rate was higher in the UW group than in the LR group. The parameters of liver function were less significantly altered in the UW group than in the LR group. The plasma ammonia concentration was significantly (P < 0.05) lower 6 h after reperfusion in the UW group than in the LR group. A small volume of hypothermic perfusion of the liver using UW solution was safe if it returned to systemic circulation. Hypothermic perfusion of the liver using UW solution may be effective for preventing hepatic tissue injury during extended hepatectomy with hepatic vascular occlusion.

Apoptotic hepatocytes in rejection and vascular occlusion in liver allograft specimens

Programmed cell death (apoptosis) has been described in different hepatobiliary diseases and in immune-mediated cytotoxicity. Apoptosis of hepatocytes and bile duct epithelial cells was detected in chronic liver allograft rejection. In severe acute rejection a DNA fragmentation in-situ assay showed positivity of apoptotic cells and centrilobular necrosis. Although apoptosis is triggered by ischaemia, the potential role of apoptosis in tissue damage caused by hepatic vascular occlusion after orthotopic liver transplantation has not yet been investigated. We examined biopsies for apoptotic cell death in 50 liver allografts: 29 with acute liver rejection, six without rejection, five time-zero biopsies, and 10 cases with hepatic artery thrombosis. In addition to a semiquantitative assessment of apoptotic bodies in haematoxylin and eosin stains, an in-situ end nick-labelling technique (TUNEL) was used to detect DNA fragmentation. In all cases with hepatic artery thrombosis the incidence of apoptosis was found significantly increased in comparison to acute rejection. As apoptosis is a mechanism in the early stages of tissue damage prior to necrosis, increased apoptosis in liver allograft biopsies might be regarded as a signal of early ischaemia indicating initial vascular occlusion.

Surgical Management of Multiple Congenital Intrahepatic Shunts in Two Dogs

To present details of an unusual type of portosystemic shunt and its surgical management in two dogs. Two young dogs that had a tentative diagnosis of a portosystemic shunt on the basis of clinical signs and serum biochemical abnormalities. Abdominal ultrasonography and contrast portography demonstrated multiple intrahepatic shunts. In both cases, the multiple shunts arose from a single branch of the portal vein. It was possible to locate and attenuate flow through the shunts via a transportal venotomy under conditions of hepatic vascular occlusion. Clinical and biochemical abnormalities resolved after surgery in both dogs. Postoperative sonography revealed complete obliteration of the shunt plexus in one of the dogs.

Techniques, hemodynamic monitoring, and indications for vascular clamping during liver resections.

Prevention of intraoperative blood loss during liver resection is an essential prognostic factor for reducing postoperative morbidity and mortality. Several procedures are currently available to ensure vascular occlusion, ranging from selective clamping of a segmental pedicle to total hepatic vascular occlusion. The type of vascular occlusion should be selected according to the indication and, in particular, according to the site of the tumor, presence of associated underlying liver disease, the patient's cardiovascular status, and the experience of the operator. The surgical strategy should be defined with the anesthesiologist and the type of hemodynamic monitoring selected should allow the best choice for management and prevention of complications such as bleeding and air embolism. Transesophageal echocardiography seems to be a new and promising method in this setting.

Uric acid changes in serum during different forms of hepatic vascular inflow occlusion

The present study was conducted to develop an efficient marker which can evaluate the influence of the occlusion of hepatic vascular inflow, which technique is commonly used in major liver surgery or in liver transplantation. Serum samples from the rats induced by hepatic vascular inflow occlusion were analyzed with high performance liquid chromatography with the electrochemical detection, and a substance which changed in accordance with the duration of the occlusion was obtained. Both the retention time and the ultraviolet absorption spectra of the substance completely agreed with those of an authentic uric acid and the substance was ultimately determined to be uric acid. To evaluate the changes in serum uric acid during different forms of hepatic vascular inflow occlusion we devised the four types of experimental model, viz. the occlusion of hepatic artery, portal vein, both hepatic artery and portal vein and both hepatic artery and portal vein of left hepatic lobes. From the device of experiments our results indicated that in the early stage of hepatic vascular inflow occlusion the high values of serum uric acid did not reflect the damage of hepatic circulation but rather responded to the intestinal congestion. Our results also indicated that even after the declamping of hepatic vascular inflow if high values of serum uric acid are prolonged it means the deterioration of the portocaval circulation including both intestinal and hepatic circulation. So that the evaluation of the severity of injured liver due to hepatic vascular inflow occlusion should be done with the caution especially in vivo study when uric acid values are used as a marker.

Transportal approach for attenuating intrahepatic portosystemic shunts in dogs.

A novel surgical approach, using portal venotomy during total hepatic vascular occlusion, was used to locate and attenuate congenital intrahepatic portosystemic shunts in nine dogs. Shunt location was consistent with a persistent ductus venosus in only two dogs. In the remaining seven dogs the shunts were window-like orifices arising from either the left (two dogs) or right portal vein branch (five dogs) and communicating with the ipsilateral hepatic vein or caudal vena cava. The transportal approach using total hepatic vascular occlusion consistently provided good access to the portosystemic shunts, including those with window-like communications. A 7 to 16 minute period of total vascular occlusion was well-tolerated hemodynamically, with few intraoperative complications. Intrahepatic shunts were successfully attenuated in eight dogs, while one dog with portal atresia was euthanatized. The postoperative course was complicated by high protein pulmonary edema (one dog), an encapsulated biliary pseudocyst (one dog) and uncontrollable hemorrhage caused by an uncharacterized coagulopathy (one dog). Three dogs required a second operation to further attenuate their shunts. The clinical condition of all seven surviving dogs was improved after surgery.

Carcinoid Tumors: Imaging Procedures and Interventional Radiology

The hypervascular nature of carcinoid tumors and their metastases allows a more aggressive role by the radiologist in diagnosis and interventional management. Double-contrast gastrointestinal studies still best define the primary neoplasms. Appendiceal tumors, the most frequent site of carcinoids, frequently escape radiologic detection until large enough to be discovered by computed tomography (CT). Superior mesenteric arteriography of the small bowel and cecum is useful when the scanning procedures are not revealing. The "spokewheel" configuration of the desmoplastic mesenteric masses and lymph node metastases are best seen by CT, whereas hepatic metastases can be demonstrated by CT, CT-angioportography (CTAP), ultrasonography (US), magnetic resonance imaging (MRI), and octreotide scintigraphy. Percutaneous needle biopsy with radiologic guidance confirms the diagnosis of carcinoid tumors and their metastases. Hepatic arteriography is frequently performed in preparation for hepatic embolization or chemoembolization. Hepatic vascular occlusion therapy, the procedure of choice for the management of inoperable carcinoid liver metastases, results in a partial response in at least 50% of patients and a mortality rate of 5%. Chemoembolization with microencapsulated cytotoxic agents and direct percutaneous ethanol injection should also be considered for the treatment of liver metastases.

The safety of total hepatic vascular occlusion in rabbits with acute extrahepatic cholestasis.

The technique of normothermic total hepatic vascular occlusion (THVO) is achieved by concomitant clamping of the inferior vena cava above and below the liver in addition to portal inflow occlusion. In this study we investigated the use of THVO for 45 min in a rabbit model with acute cholestasis of 10 days' duration. In rabbits with normal preoperative liver functions (control group), serum total bilirubin, glutamic-pyruvic transaminase (SGPT), glutamic-oxaloacetic transaminase (SGOT), alkaline phosphate, and gamma-glutamyltranspeptidase levels returned to normal ranges within a week after THVO. In the group with persistent cholestasis THVO was performed 10 days after ligation of the extrahepatic bile duct. Total bilirubin and canalicular enzymes remained high while the SGOT and SGPT peaked and almost returned to the preoperative levels at 7 days following THVO in this group. A third group of animals also underwent THVO 10 days after ligation of their extrahepatic bile ducts with relief of the obstruction with a Teflon stent immediately after THVO. This group also showed the trend of normalization of liver canalicular and parenchymal enzymes and bilirubin by the end of 7 days. This study demonstrated the feasibility of THVO in rabbits with acute extrahepatic cholestasis whether the extrahepatic biliary obstruction persisted or not.

Experimental study of liver injury after partial hepatectomy with intermittent or continuous hepatic vascular occlusion. Differences in tolerance to ischemia between normal and cirrhotic livers.

The degree of residual liver injury in normal and cirrhotic rats undergoing 70% hepatectomy with hepatic inflow occlusion was examined. The total duration of clamping was 60 min and animals were divided into 3 groups according to the ischemic modality: a 15-min intermittent clamping group (group I); a 30-min intermittent clamping group (group II), and a 60-min continuous clamping group (group III). In normal liver rats, the survival rates after operation in groups I, II and III were 90, 90 and 30%, respectively, compared to 70, 50 and 38%, respectively, in cirrhotic rats. The serum aspartate aminotransferase (AST) level increased markedly with prolongation of each period of clamping in rats with normal liver, showing higher AST levels than those with cirrhotic liver. The liver tissue adenosine-5'-triphosphate (ATP) levels and energy charge (EC) values decreased with prolongation of each period of clamping. Cirrhotic livers showed lower ATP levels and EC values than normal livers. Although there was no significant difference in the mitochondrial function between normal and cirrhotic livers in the group of the same form of ischemia, phosphorylative efficiency of mitochondria was maintained satisfactorily in normal groups I and II and in the cirrhotic group I. Even though cirrhotic livers showed a smaller necrotic response to ischemia than normal livers, they were more vulnerable to ischemia because of an inability to maintain energy metabolism. Therefore, when performing resection of a cirrhotic liver, a 15-min intermittent clamping method should be adopted.

Liver injury following normothermic ischemia in steatotic rat liver.

The influence of normothermic ischemia on steatotic liver was compared with that on healthy liver in rats. Steatotic liver was induced with 4 wk of a choline-deficient diet. We used a procedure of subcutaneous spleen transposition to develop portosystemic collaterals to avoid splanchnic stasis during total hepatic vascular occlusion. One-week survival rates after 30, 45, and 60 min of normothermic ischemia were 75%, 20% and 0% in the steatotic liver group and 100%, 90% and 70% in the control group, respectively. Significantly poor restoration of energy metabolism was observed in the steatotic liver group. After 1 hr of reflow following 45 and 60 min of ischemia, ATP was restored to 74% and 50%, respectively, of the preischemic level in healthy liver but to only 44% and 27% respectively, in steatotic liver. Microscopically, focal hemorrhage, disruption of the sinusoidal microvasculature and occasional spotty necrosis of hepatocytes were demonstrated after 1 hr of reflow following ischemia in steatotic liver, but no significant changes were evident in healthy liver. This microcirculatory alteration seems to be responsible for the loss of organ viability in steatotic liver. We suggest that steatotic liver is more vulnerable than healthy liver to normothermic ischemia in the rat.