Hepatic Portal Flow Research Articles

Comparison of CT and MRI in the Diagnosis of Liver Tumors: A Retrospective Case-Control Analysis.

To compare the diagnostic value of multi-slice computed tomography (CT) and magnetic resonance imaging (MRI) in liver tumors. Retrospective selection of CT and MRI imaging data from 109 cases of liver tumors treated in our hospital from January 2020 to March 2023. The selection was determined through pathological examination. According to the pathological examination results, 61 cases were benign tumors, and 48 cases were malignant tumors. The hepatic portal flow (HPF), hepatic artery perfusion index (HPI) and hepatic artery perfusion (HAF) of malignant tumors were significantly lower than in benign tumors (P<0.05). The signal enhancement ratio of malignant tumors was significantly higher than in benign tumors, and the peak time was significantly lower than in benign tumors (P<0.05). The sensitivity (97.92%) and accuracy (97.25%) of the combined examination were significantly higher than those of MRI (83.33%, 90.83%) or CT alone (81.25%, 88.99%) (P<0.05). CT and MRI have high application value in the diagnosis and evaluation of liver tumors, and the combination of these two methods can further improve diagnostic sensitivity and accuracy, providing an objective reference for early diagnosis and treatment of liver cancer.</p>.

Meso-Rex bypass for the management of extrahepatic portal vein obstruction in adults (with video)

BackgroundExtrahepatic portal vein obstruction (EHPVO) results in severe portal hypertension (PHT) leading to severely compromised quality of life. Often, pharmacological and endoscopic management is unable to solve this problem. Restoring hepatic portal flow using meso-Rex bypass (MRB) may solve it. This procedure, uncommon in adult patients, is considered the treatment of choice for EHPVO in children. MethodsFrom 1997 to 2018, 8 male and 6 female adults, with a median age of 51 years (range 22–66) underwent MRB procedure for EHPVO at the University Hospitals Saint-Luc in Brussels, Belgium. Symptoms of PHT were life altering in all but one patient and consisted of repetitive gastro-intestinal bleedings, sepsis due to portal biliopathy, and/or severe abdominal discomfort. The surgical technique consisted in interposition of a free venous graft or of a prosthetic graft between the superior mesenteric vein and the Rex recess of the left portal vein. ResultsMedian operative time was 500 min (range 300–730). Median follow-up duration was 22 months (range 2–169). One patient died due to hemorrhagic shock following percutaneous transluminal intervention for early graft thrombosis. Major morbidity, defined as Clavien-Dindo score ≥ III, was 35.7% (5/14). Shunt patency at last follow-up was 64.3% (9/14): 85.7% (6/7) of pure venous grafts and only 42.9% (3/7) of prosthetic graft. Symptom relief was achieved in 85.7% (12/14) who became asymptomatic after MRB. ConclusionsAdult EHPVO represents a difficult clinical condition that leads to severely compromised quality of life and possible life-threatening complications. In such patients, MRB represents the only and last resort to restore physiological portal vein flow. Although successful in a majority of patients, this procedure is associated with major morbidity and mortality and should be done in tertiary centers experienced with vascular liver surgery to get the best results.

Somatostatin as Inflow Modulator in Liver-transplant Recipients With Severe Portal Hypertension: A Randomized Trial.

To investigate the safety and efficacy of somatostatin as liver inflow modulator in patients with end-stage liver disease (ESLD) and clinically significant portal hypertension (CSPH) undergoing liver transplantation (LT) (ClinicalTrials.gov number,01290172). In LT, portal hyperperfusion can severely impair graft function and survival, mainly in cases of partial LT. Thirty-three patients undergoing LT for ESLD and CSPH were randomized double-blindly to receive somatostatin or placebo (2:1). The study drug was administered intraoperatively as 5-mL bolus (somatostatin: 500 μg), followed by a 2.5 mL/h infusion (somatostatin: 250 μg/h) for 5 days. Hepatic and systemic hemodynamics were measured, along with liver function tests and clinical outcomes. The ischemia-reperfusion injury (IRI) was analyzed through histological and protein expression analysis. Twenty-nine patients (18 receiving somatostatin, 11 placebo) were included in the final analysis. Ten patients responded to somatostatin bolus, with a significant decrease in hepatic venous portal gradient (HVPG) and portal flow of -28.3% and -29.1%, respectively. At graft reperfusion, HVPG was lower in patients receiving somatostatin (-81.7% vs -58.8%; P = 0.0084), whereas no difference was observed in the portal flow (P = 0.4185). Somatostatin infusion counteracted the decrease in arterial flow (-10% vs -45%; P = 0.0431). There was no difference between the groups in the severity of IRI, incidence of adverse events, long-term complications, graft, and patient survival. Somatostatin infusion during LT in patients with CSPH is safe, reduces the HVPG, and preserves the arterial inflow to the graft. This study establishes the efficacy of somatostatin as a liver inflow modulator.

A Bypassing Technique for the Remedy of Portal Hypertension through Extra Hepatic Portal Vein Obstruction by CFD Analysis

Extra-hepatic portal vein obstruction (EHPVO) is the blockage to the flow of blood in the portal vein before reaches to the liver. EHPVO is the common cause of portal hypertension in children in the most Asian countries. Examination reveals that the presence of block in the main portal vein may be responsible for the shrinkage of vein with manifold pernicious complication. The “shunt” policy is a fruitful source of restoration of the hepatic portal flow. This study shows that a new approach of bypassing (or shunting) to the blocked (thrombosed) region of the portal vein is a significant way of reducing portal hypertension and restoration of blood circulation. We studied EHPVO case through computational fluid dynamics (CFD) analysis by considering partial block formation and side to side shunt scheme inside the main portal vein. The constitutive equation for non-Newtonian fluidand energy equation are solved by control volume technique. Our study reveals that the shunting technique is strongly effective for the reconstitution of portal venous flow to the liver with lower tissue stress and rapid regression of clinical signs of portal hypertension. This new technique may potentially applicable for medication of EHPVO when shunting procedures are indicated.&#x0D; GANIT J. Bangladesh Math. Soc.Vol. 38 (2018) 89-104

Perihilar Hepatectomy for Hepatolithiasis with Compressed Hilar Bile Duct Induced by Perihilar Hyperplasia of Liver

Background: Stone recurrence is a major problem limiting the effects of surgical treatment for hepatolithiasis. It was showed that hyperplasia of perihilar liver may compress the hepatic portal and cause deficient bile flow because of compressed hilar bile duct, thereby leading to the formation of bile stasis and precipitating stone recurrence. This retrospective study aimed to evaluate the efficiency of perihilar hepatectomy for hepatolithiasis with compressed hilar bile duct induced by perihilar hyperplasia of liver. Methods: 135 patients with compressed hilar bile duct induced by hypertrophied perihilar liver were included in this study from January 2011 to July 2016. Among these patients, 77 underwent conventional operation procedure (control group) and 58 underwent conventional operation procedure added by perihilar hepatectomy (perihilar hepatectomy group). Clinical data containing preoperative data, intraoperative data, operation complications, and short-term and long-term outcomes were collected. Results: The demographic and disease-related characteristics of the two groups were comparable. The two groups were not remarkably different in operation-related characteristics. The incidence of bile leakage in the perihilar hepatectomy group was substantially higher than that in the control group. Other postoperative complications were not remarkably different between the two groups. In the long-term postoperative follow-up period, the incidence of the recurrence of stones and cholangitis in the control group was considerably higher than that in the perihilar hepatectomy group. Conclusions: Based on conventional operation procedure, additional perihilar hepatectomy is a reliable intervention with definite clinical effects for hepatolithiasis with compressed hilar bile duct induced by hypertrophied perihilar liver.

Selective hepatic artery clamping in laparoscopic hepatectomy: it pretty much works

Bleeding control during parenchymal transection in any liver surgery is the keystone for technical success. Since the beginning of the 20th century, when James Hogarth Pringle described a maneuver in witch the hepatoduodenal ligament in clamped in order to interrupt the blood flow through the hepatic artery and the portal vein and thus helping to control bleeding from the liver, the so called Pringle maneuver is virtually the only technique used with this purpose. Although being very effective, it has the disadvantage of inducing warm hepatic ischemia and the consequent need of being applied in an intermittent fashion in order not to motivate postoperative hepatic failure. Since it has been previously demonstrated that under pneumoperitoneum the hepatic portal flow is reduced up to 60% with no compensatory hepatic artery flow (hepatic artery buffer effect), we proposed the selective hepatic artery clamping during laparoscopic hepatectomies. This clamping technique that can be performed in a continuous manner not resulting in hepatic ischemia and is also very effective in reducing blood loss during parenchymal transection. We have performed this technique in several patients submitted to laparoscopic hepatectomies (from non-anatomical wedge resection to right anatomic hepatectomies) and it proved to be an effective and safe technique.

Hepatic Hemodynamics and Portal Flow Modulation: The A2ALL Experience.

A principal aim of the Adult-to-Adult Living Donor Liver Transplantation Cohort Study was to study hepatic blood flow and effect of portal flow modulation on graft outcomes in the setting of increasing use of smaller and left lobe grafts. Recipients of 274 living donor liver transplant were enrolled in the Adult-to-Adult Living Donor Liver Transplantation Cohort Study, including 233 (85.0%) right lobes, 40 (14.6%) left lobes, and 1 (0.5%) left lateral section. Hepatic hemodynamics were recorded after reperfusion. A total of 57 portal flow modulations were performed on 52 subjects. Modulation lowered portal pressure in 68% of subjects with inconsistent effects on hepatic arterial and portal flow. A higher rate of graft dysfunction was observed in modulated vs. unmodulated subjects (31% vs. 18%; P = 0.03); however, graft survival in modulated subjects was not different from unmodulated subjects at 3 years. These results suggest the need for a study using a prespecified portal flow modulation protocol with defined indications to better define the effects of these interventions.

Imaging the Rex vein preoperatively using wedged hepatic venous portography

Mesentericoportal bypass, the Rex shunt, restores the physiological hepatic portal flow and reduces the clinical sequelae of portal hypertension in children with extrahepatic portal vein obstruction (EHPVO). The preoperative evaluation includes an accurate assessment of the portal venous inflow and outflow. The former is readily assessed by ultrasound and MRI, while the outflow intrahepatic portal vein is harder to assess. To assess the efficacy of wedged hepatic venous portography (WHVP) at detecting a patent Rex vein preoperatively in children with EHPVO who were considered for mesenterico-portal bypass. A single-institution retrospective chart review was undertaken for children with EHPVO who had been considered for a mesoportal bypass between January 2001 and January 2010. Sixteen children were considered for mesoportal bypass, including four post reduced-size liver transplant patients. Ten children (63%) underwent WHVP. The Rex vein was clearly identified in 8/10 (80%). One Rex vein was seen at surgery but not demonstrated at WHVP. Six mesoportal bypasses were performed without WHVP, of which three (50%) were successful. WHVP had a sensitivity of more than 80% and specificity of 100% in the preoperative patency assessment of the Rex vein.

Portal Vein Arterialization for Hepatic Artery Thrombosis in Liver Transplantation: A Case Report, Doppler-Ultrasound Aspects, and Review of the Literature

Portal vein arterialization (PVA) is a salvage procedure for insufficient hepatic arterial or portal vascularization. It plays a role in auxiliary and orthotopic liver transplantation (OLT). In OLT, current indications for PVA include hepatic artery thrombosis (HAT), pre-OLT or post-OLT extended splanchnic vein thrombosis, intraoperative low portal flow, and anatomic variations like the absence of portal and mesenteric veins. Out of the transplantation domain, PVA is used both in extensive surgery for malignancies of the liver, biliary tract, and pancreas and in the treatment of fulminant hepatic failure (FHF) due to intoxications. We describe a case of acute post-OLT HAT successfully treated with PVA as a short bridge to retransplantation. By Doppler ultrasound of clinical PVA we detected an increased intrahepatic portal flow velocity, with disappearance of the arterial spikes, a finding that needs further investigation. PVA represents a rare surgical procedure. In fact, it has been used most of all in urgent conditions or in case of abrupt vascular complications during surgery. According to the literature, PVA emerges as a salvage procedure for poor arterial or portal hepatic flow, both in OLT and in general abdominal surgery. The outcome of this procedure is unpredictable. The aim of the shunt is to gain time, awaiting the onset of collateral arterial vessels or the performance of definitive surgery. Its early thrombosis may be a catastrophic event, due to acute liver ischemia. In contrast, a late occlusion is often well tolerated. Strict surveillance is always useful because sometimes it is mandatory to embolize the arterioportal fistula to treat or to prevent the onset of portal hypertension.

Prioritizing blood flow: cardiovascular performance in response to the competing demands of locomotion and digestion for the Burmese python,Python molurus

Individually, the metabolic demands of digestion or movement can be fully supported by elevations in cardiovascular performance, but when occurring simultaneously, vascular perfusion may have to be prioritized to either the gut or skeletal muscles. Burmese pythons (Python molurus) experience similar increases in metabolic rate during the digestion of a meal as they do while crawling, hence each would have an equal demand for vascular supply when these two actions are combined. To determine, for the Burmese python, whether blood flow is prioritized when snakes are digesting and moving, we examined changes in cardiac performance and blood flow in response to digestion, movement, and the combination of digestion and movement. We used perivascular blood flow probes to measure blood flow through the left carotid artery, dorsal aorta, superior mesenteric artery and hepatic portal vein, and to calculate cardiac output, heart rate and stroke volume. Fasted pythons while crawling experienced a 2.7- and 3.3-fold increase, respectively, in heart rate and cardiac output, and a 66% decrease in superior mesenteric flow. During the digestion of a rodent meal equaling in mass to 24.7% of the snake's body mass, heart rate and cardiac output increased by 3.3- and 4.4-fold, respectively. Digestion also resulted in respective 11.6- and 14.1-fold increases in superior mesenteric and hepatic portal flow. When crawling while digesting, cardiac output and dorsal aorta flow increased by only 21% and 9%, respectively, a modest increase compared with that when they start to crawl on an empty stomach. Crawling did triggered a significant reduction in blood flow to the digesting gut, decreasing superior mesenteric and hepatic portal flow by 81% and 47%, respectively. When faced with the dual demands of digestion and crawling, Burmese pythons prioritize blood flow, apparently diverting visceral supply to the axial muscles.

Changes in Visceral Flow Induced by Laparoscopic and Open Living-Donor Nephrectomy: Experimental Model

Increased intra-abdominal pressure during laparoscopy changes visceral flow. The objective of the present study was to analyze the changes in peripheral and intra-abdominal flow induced by laparoscopic living-donor nephrectomy in an experimental model. Twenty pigs underwent left-sided nephrectomy, 10 at laparoscopy and 10 in an open approach. Renal blood flow (RBF), hepatic arterial flow (HAF), portal flow (PF), and carotid flow (CF) were measured using an electromagnetic probe placed around these vessels. Comparative analysis between the groups demonstrated increased CF (mean [SD], 125.73 [41.69] vs 291.70 [51.52] mL/min; P < .001) and decreased PF (973.67 [131.70] vs 546.83 [217.53] mL/min; P = .001) and HAF (278.00 [94.71] vs 133.33 [112.32] mL/min; P = .03) in pigs that underwent laparoscopy compared with those who underwent open surgery; no significant differences were observed in RBF. In conclusion, laparoscopic nephrectomy induces increased CF and decreased total hepatic flow, at the expense of PF and HAF. With adequate intravascular volume expansion, no differences were observed in RBF between the laparoscopic and open approaches.

Splenic-intrahepatic left portal shunt in an adult patient with extrahepatic portal vein obstruction without recurrence after pancreaticoduodenectomy

In the last decade, a superior mesenteric-intrahepatic left portal shunt (Rex shunt) has been reported for successful management of extrahepatic portal vein obstruction in children. However, in adults, a mesocaval shunt has been generally performed for the surgical management of extrahepatic portal vein obstruction because of the complexity of the underlying disease and the difficulty of the superior mesenteric-intrahepatic left portal shunt. We herein report an adult patient who was successfully treated by splenic-intrahepatic left portal shunt with an artificial graft (6-mm polytetrafluoroethylene) for complete obstruction of the extrahepatic portal vein following pancreaticoduodenectomy. The shunt procedure not only relieved portal hypertension but also restored hepatic portal flow. In the near future, the Rex shunt should be considered for a beneficial management of extrahepatic portal vein obstruction, even in adults.

Polyvinyl Alcohol Embolization Adjuvant to Oily Chemoembolization in Advanced Hepatocellular Carcinoma with Arterioportal Shunts

ObjectiveTo assess the feasibility and safety of polyvinyl alcohol (PVA) embolization adjuvant to transarterial oily chemoembolization (P-TACE) in advanced hepatocellular carcinoma (HCC) with arterioportal shunts (APS).Materials and MethodsNineteen patients who underwent PVA embolization for APS before a routine chemoembolization (TACE) procedure were retrospectively reviewed. 10 of these 19 patients underwent follow-up TACE or P-TACE after P-TACE (Group A), but nine patients underwent only initial P-TACE because of progression of HCC and/or underlying liver cirrhosis (Group B). Hepatic function tests, APS grades, and portal flow directions were evaluated before and after P-TACE sessions. Complications after procedures and survival days were also evaluated.ResultsIn group A, APS grade was improved in eight patients and five of six patients with hepatofugal flow showed restored hepatopetal flow postoperatively. No immediate complication was developed in either group. Transient hepatic insufficiency developed in eight (42.1%) of 19 patients after P-TACE, and seven (87.5%) of these eight recovered within two weeks under conservative care. The mean and median survival time all study subjects was 280 days and 162 days.ConclusionP-TACE is feasible and safe in advanced HCC patients with APS.

Correction of Extrahepatic Portal Vein Thrombosis by the Mesenteric to Left Portal Vein Bypass

The goal of this study was to determine the effectiveness of mesenteric vein to left portal vein bypass operation (MLPVB) in correcting extrahepatic portal vein thrombosis (EHPVT) in children. The treatment of idiopathic EHPVT has been primarily palliative, whereas MLPVB restores hepatic portal flow in patients with EHPVT. Thirty-four children with symptomatic EHPVT underwent surgery with intent to perform MLPVB and were followed for up to 7 years. MLPVB was successful in 31 patients (91%), all of whom maintain patent vein grafts and have symptomatic relief of EHPVT in follow-up. All patients had complete relief from gastrointestinal bleeding. Patients with hypersplenism had significant increases in platelet and leukocyte counts and reduction in spleen size. Superior mesenteric vein flow increased from 119 +/- 66 mL/min before bypass to 447 +/- 225 mL/min (P < 0.0001) after surgery. Postoperative blood flow in the bypass graft expressed as a fraction of calculated ideal portal flow for size correlated inversely with age (P < 0.001). Left-portal vein diameter increased from 2.6 +/- 1.6 mm to 7.3 +/- 2.4 mm 2 years after surgery (P < 0.002). Liver volume increased from 703 +/- 349 cm3 to 799 +/- 351 cm3 1 week after surgery (P < 0.001). Prothrombin time improved to normal in all patients 1 year after surgery. MLPVB provides excellent relief of symptoms in children with idiopathic EHPVT and results in liver growth and normalization of coagulation parameters. This surgery is corrective and should be done at as early an age as possible.

Hepatic flow parameters measured with MR imaging and Doppler US: correlations with degree of cirrhosis and portal hypertension.

To determine the correlations between hemodynamic parameters of hepatic flow measured with magnetic resonance (MR) imaging and Doppler ultrasonography (US) and the severity of cirrhosis and portal hypertension. Forty-six patients referred for measurements of portal venous pressure (three with normal liver, 12 with chronic hepatitis, and 31 with cirrhosis [10 with Child-Pugh class A cirrhosis; 13 with class B cirrhosis; and eight with class C cirrhosis]) were included in the study. Apparent liver perfusion, apparent arterial and portal perfusion, portal fraction, distribution volume, and mean transit time were measured with dynamic contrast material-enhanced MR imaging. Portal velocity, portal flow, congestion index, right hepatic artery resistance index, and modified hepatic index were measured with Doppler US. Results in patients with cirrhosis and those without cirrhosis were compared with the Wilcoxon rank sum test. Correlations were assessed with Spearman rank correlation coefficients. With MR imaging, all flow parameters except distribution volume were significantly different between patients with and those without cirrhosis (P <.05). There was a significant correlation between all flow parameters measured with MR imaging and portal pressure (P <.02). Apparent arterial (P =.024) and portal (P <.001) perfusion, portal fraction (P <.001), and mean transit time (P =.004) were correlated with Child-Pugh class. Flow parameters measured with Doppler US did not differ significantly between patients with and those without cirrhosis. Only right hepatic arterial resistance (P <.007) and portal flow (P <.043) were weakly (r < 0.7) correlated with portal pressure. No Doppler US parameter was correlated with Child-Pugh class. Hepatic flow parameters measured with MR imaging correlate with the severity of cirrhosis and portal hypertension. Doppler US parameters are only weakly correlated with portal pressure.

Hepatic Vascular Response to Elevated Intraperitoneal Pressure in the Rat

The rat is increasingly being used to study the physiological response to elevated intra-abdominal pressure (IAP) during laparoscopic surgery. Although decreased portal venous flow associated with the elevated IAP has been reported in large animals, little information is available in rats. Furthermore, the relative blood flow changes in the hepatic artery and portal vein have not been reported. Therefore, this study was performed to elucidate the change in systemic and splanchnic circulation, including hepatic arterial and portal venular flow, during pneumoperitoneum in rats. Sprague–Dawley rats were assigned into either a ventilated or nonventilated group and then subjected to various levels of IAP (0, 5, 10, and 20 mm Hg) using carbon dioxide gas. At each pressure, both cardiac output and splanchnic organ flow were determined using fluorescent microspheres. There was no obvious hemodynamic difference between the ventilated and nonventilated groups. Mean arterial pressure and cardiac index were significantly lower with 20 mm Hg of IAP compared to 0 mm Hg in both groups. Flow to the spleen, stomach, duodenum, total intestine, and portal vein was all decreased by increasing IAP (P < 0.05 at 20 mm Hg compared to 0 mm Hg) and was significantly correlated to the decrease in cardiac index. However, the hepatic arterial flow was relatively preserved throughout all levels of IAP, suggesting activation of the hepatic arterial buffer response. We conclude that the decreased splanchnic flow during pneumoperitoneum largely depends on the decreased cardiac index. Hepatic artery flow, however, is selectively preserved and may provide protection for liver function during sustained elevations in IAP.

Influence of Liver Fibrosis on Hepatic Artery Doppler Resistance Index in Chronic Hepatitis of Viral Origin

Hepatic arterial Doppler sonography is increasingly being used in liver diagnostics. The determinants of the elevation of hepatic artery impedance indexes in chronic liver disease, however, have still not been fully clarified. The aim of the present study was to investigate the relationship between histological alterations and liver circulation in chronic hepatitis. Hepatic artery resistance index and portal flow velocity were measured using Doppler sonography in 47 patients with chronic hepatitis of viral origin diagnosed at histopathology. The patients were divided into two groups, those with mild and those with severe alterations, in accordance with the various histological parameters of the Knodell scoring system. Hepatic artery resistance index and age were higher in patients with more severe liver fibrosis (respectively 0.638 +/- 0.084 and 39.0 +/- 10.9 (years) in mild fibrosis versus 0.687 +/- 0.060 and 49.4 +/- 14.4 (years) in severe fibrosis; P < 0.05 for both), whereas no difference between the two groups was found for the other histological features (degeneration, inflammation and necrosis), nor for portal flow velocity. The increase in hepatic artery resistance index appears to be influenced by the extent of fibrous tissue deposition in the liver, determined by chronic inflammation and repair and, secondly, by ageing.

Influence of Liver Fibrosis on Hepatic Artery Doppler Resistance Index in Chronic Hepatitis of Viral Origin

Background: Hepatic arterial Doppler sonography is increasingly being used in liver diagnostics. The determinants of the elevation of hepatic artery impedance indexes in chronic liver disease, however, have still not been fully clarified. The aim of the present study was to investigate the relationship between histological alterations and liver circulation in chronic hepatitis. Methods: Hepatic artery resistance index and portal flow velocity were measured using Doppler sonography in 47 patients with chronic hepatitis of viral origin diagnosed at histopathology. The patients were divided into two groups, those with mild and those with severe alterations, in accordance with the various histological parameters of the Knodell scoring system. Results:

A non-invasive isotope dilution technique for quantifying hepatic blood flow using radiolabelled red blood cells.

Clinically significant changes in hepatic haemodynamics accompany the development of portal hypertension, hepatocellular carcinoma, liver metastases and liver cirrhoses, and after major liver resection. Hepatic blood flow parameters, such as hepatic arterial flow (HAF), hepatic portal flow (HPF), total hepatic blood flow (THBF) and hepatic perfusion index (HPI), are useful adjuncts to the diagnosis of liver pathology, the evaluation of disease progress and prognostication. Here, we describe a non-invasive method that combines the measurement of these parameters in a single study in real time. Red blood cells from eight pigs were labelled with 99Tc(m) using an in-vitro method and re-injected into the pigs. Data acquisition over the heart, lungs, liver and kidneys was started immediately and a blood sample was obtained 15 min post-injection. Hepatic arterial flow was determined from the ratio of the maximum gradients between the integrated time-activity curve of the left ventricle and the first-pass time-activity curve of the liver before the peak of the kidneys time-activity curve. The hepatic perfusion index was determined by comparing the slope of the liver time-activity curve before and after the kidney peak. Hepatic portal flow was determined from the hepatic arterial flow and the hepatic perfusion index, and total hepatic blood flow was determined as the sum of arterial and portal flow. The results were compared against those obtained from a clearance method using 99Tc(m)-DISIDA. The average hepatic perfusion index was 0.38, and the average hepatic arterial flow and hepatic portal flow were 168.3 +/- 52.9 and 274.6 +/- 60.1 ml x min(-1) respectively. The average total hepatic blood flow was 442.8 +/- 53.5 ml x min(-1), while the total hepatic flow determined by 99Tc(m)-DISIDA clearance was 419.7 +/- 62.6 ml x min(-1). No significant difference in total hepatic blood flow was found between the two methods. The results of this study show that it is possible to obtain all hepatic haemodynamics data in a single study using a non-invasive method.

Direct bypassing of extrahepatic portal venous obstruction in children: A new technique for combined hepatic portal revascularization and treatment of extrahepatic portal hypertension

Background: Decompression of extrahepatic portal hypertension by directly bypassing the thrombosed portal vein has never been reported in cases of children with idiopathic (or neonatal portal vein obstruction and cavernoma. Methods: Seven children (15 years or younger) with portal vein obstruction requiring surgical decompression (urgently in two cases), and in whom preoperative Doppler had shown that the intrahepatic portal branches were hypoplastic but free of thrombus, were included in a pilot study. The cavernoma was bypassed by interposing a venous jugular autograft between the superior mesenteric vein and the distal portion of the left portal vein. Patients received follow-up using routine clinical parameters, upper gastrointestinal endoscopy, and Doppler ultrasound. Results: The mesenterico-portal bypass restored a direct (physiological) hepatopetal portal flow. The operation resulted in effective portal decompression as demonstrated by decrease of the pressure gradient, rapid regression of clinical signs of portal hypertension, and definitive control of bleeding. Conclusions: This study shows that direct bypassing of portal cavernoma is possible and results in effective portal decompression. Restoration of the hepatic portal flow is a major advantage compared with conventional surgical shunting procedures. This new technique is potentially applicable to two thirds of children with portal vein thrombosis and should be considered when shunting procedures are indicated.