Hemodynamic changes in splanchnic blood vessels in portal hypertension

A 10-year Australian experience of rare intraabdominal venous thrombosis with comparison to deep vein thrombosis and pulmonary embolism

OBJECTIVE

Intra-abdominal venous thromboembolism is rare with heterogeneous management. We aim to evaluate these thrombosis and compare them to deep vein thrombosis and/or pulmonary embolism.

METHOD

A 10-year retrospective evaluation of consecutive venous thromboembolism presentations (January 2011-December 2020) at Northern Health, Australia, was conducted. A subanalysis of intraabdominal venous thrombosis involving splanchnic, renal and ovarian veins was performed.

RESULTS

There were 3343 episodes including 113 cases of intraabdominal venous thrombosis (3.4%) - 99 splanchnic vein thrombosis, 10 renal vein thrombosis and 4 ovarian vein thrombosis. Of the splanchnic vein thrombosis presentations, 34 patients (35 cases) had known cirrhosis. Patients with cirrhosis were numerically less likely to be anticoagulated compared to noncirrhotic patients (21/35 vs. 47/64, P  = 0.17). Noncirrhotic patients ( n  = 64) were more likely to have malignancy compared to those with deep vein thrombosis and/or pulmonary embolism (24/64 vs. 543/3230, P  < 0.001), including 10 patients diagnosed at time of splanchnic vein thrombosis presentation. Cirrhotic patients reported more recurrent thrombosis/clot progression (6/34) compared to noncirrhotic patients (3/64) (15.6 vs. 2.3 events/100-person-years; hazard ratio 4.7 (95% confidence interval 1.2-18.9), P  = 0.030) and other venous thromboembolism patients (2.6/100-person-years; hazard ratio 4.7, 95% confidence interval 2.1-10.7; P  < 0.001) with comparable major bleeding rates. All renal vein thrombosis were provoked including five malignant-related cases while three ovarian vein thrombosis occurred postpartum. No recurrent thrombotic or bleeding complications were reported in renal vein thrombosis and ovarian vein thrombosis.

CONCLUSION

These rare intraabdominal venous thromboses are often provoked. Splanchnic vein thrombosis (SVT) patients with cirrhosis have a higher rate of thrombotic complications, while SVT without cirrhosis was associated with more malignancy. Given the concurrent comorbidities, careful assessment and individualized anticoagulation decision is needed.

Individualized total laparoscopic surgery based on 3D remodeling for portal hypertension: A single surgical team experience

Background and aims

Portal hypertension (PHT) is common in end-stage cirrhosis, and variceal bleeding is the main complication associated with mortality. Surgery is usually performed in patients with PHT with a high risk of variceal bleeding in China. This study aimed to introduce an individualized and precise total laparoscopic surgical procedure based on 3D remodeling for PHT.

Methods

From March 2013 to December 2018, 146 patients with cirrhotic PHT underwent a laparoscopic surgical procedure in our department. An individualized 3D remodeling evaluation was carried out for surgical planning.

Results

The operation time was 319.96 ± 91.53 min. Eight of 146 patients were converted to open surgery. Acute portal vein system thrombosis occurred in 10 patients (6.85%). During the first year, 11 patients (8.15%) experienced rebleeding and two (1.48%) died. 18 patients (13.33%) experienced rebleeding and three died, giving a 3-year mortality rate of 3.66%. Compared with preoperatively, the portal vein showed significant postoperative decreases in diameter, flow velocity, and flow amount, while the hepatic artery showed significant postoperative increases in diameter, flow velocity, and flow amount. A 3D liver volume evaluation found that 19 of 21 patients had a significantly increased liver volume postoperatively, and a significantly decreased MELD score.

Conclusion

This retrospective study introduced a safe, feasible, and effective individualized surgical procedure. Our results show that this surgical treatment may not only act as an effective symptomatic treatment for PHT to prevent esophageal and gastric hemorrhage, but also as an etiological treatment to increase liver function and long-term survival.

Anticoagulant therapy for splanchnic vein thrombosis: an individual patient data meta-analysis

Robust evidence on the optimal management of splanchnic vein thrombosis (SVT) is lacking. We conducted an individual patient meta-analysis to evaluate the effectiveness and safety of anticoagulation for splanchnic vein thrombosis (SVT). MEDLINE, EMBASE, and clincaltrials.gov., were searched up to June 2021 for prospective cohorts or randomized clinical trials including patients with SVT. Data from individual datasets were merged, and any discrepancy with published data was resolved by contacting study authors. Three studies for a total of 1635 patients were included. Eighty-five percent of patients received anticoagulation for a median duration of 316 days (range 1 to 730 days). Overall, incidence rates for recurrent VTE, major bleeding, and mortality were 5.3/100 patients-years (p-y) (95% CI, 5.1 to 5.5), 4.4/100 p-y (95% CI, 4.2 to 4.6), and 13.0/100 p-y (95% CI, 12.4 to 13.6), respectively. The incidence rates of all outcomes were lower during anticoagulation and higher after treatment discontinuation or when anticoagulation was not administered. In multivariable analysis, anticoagulant treatment appeared to be associated with a lower risk of recurrent VTE (Hazard Ratio [HR] 0.42; 95% CI, 0.27 to 0.64), major bleeding (HR 0.47; 95% CI, 0.30 to 0.74), and mortality (HR 0.23; 95% CI, 0.17 to 0.31). Results were consistent in patients with cirrhosis, solid cancer, myeloproliferative neoplasms, unprovoked SVT, and SVT associated with transient or persistent non-malignant risk factors. In patients with SVT the risk of recurrent VTE and major bleeding is substantial. Anticoagulant treatment is associated with reduced risk of both outcomes.

Anticoagulant therapy for splanchnic vein thrombosis: a systematic review and meta-analysis

Treatment of splanchnic vein thrombosis (SVT) is challenging, and evidence to guide therapeutic decisions remains scarce. The objective of this systematic review and meta-analysis was to determine the efficacy and safety of anticoagulant therapy for SVT. MEDLINE, EMBASE, and clinicaltrials.gov were searched from inception through December 2019, without language restrictions, to include observational studies and randomized controlled trials reporting radiological or clinical outcomes in patients with SVT. Pooled proportions and risk ratios (RRs) with 95% confidence intervals (CIs) were calculated in a random-effects model. Of 4312 records identified by the search, 97 studies including 7969 patients were analyzed. In patients receiving anticoagulation, the rates of SVT recanalization, SVT progression, recurrent venous thromboembolism (VTE), major bleeding, and overall mortality were 58% (95% CI, 51-64), 5% (95% CI, 3-7), 11% (95% CI, 8-15), 9% (95% CI, 7-12), and 11% (95% CI, 9-14), respectively. The corresponding values in patients without anticoagulation were 22% (95% CI, 15-31), 15% (95% CI, 8-27), 14% (95% CI, 9-21), 16% (95% CI, 13-20), and 25% (95% CI, 20-31). Compared with no treatment, anticoagulant therapy obtained higher recanalization (RR, 2.39; 95% CI, 1.66-3.44) and lower thrombosis progression (RR, 0.24; 95% CI, 0.13-0.42), major bleeding (RR, 0.73; 95% CI, 0.58-0.92), and overall mortality (RR, 0.45; 95% CI, 0.33-0.60). These results demonstrate that anticoagulant therapy improves SVT recanalization and reduces the risk of thrombosis progression without increasing major bleeding. The incidence of recurrent VTE remained substantial in patients receiving anticoagulation, as well. Effects were consistent across the different subgroups of patients. This trial was registered on the PROPERO database at (https://www.crd.york.ac.uk/prospero//display_record.php?ID=CRD42019127870) as #CRD42019127870.

Treatment for ascites in adults with decompensated liver cirrhosis: a network meta-analysis

BACKGROUND

Approximately 20% of people with cirrhosis develop ascites. Several different treatments are available; including, among others, paracentesis plus fluid replacement, transjugular intrahepatic portosystemic shunts, aldosterone antagonists, and loop diuretics. However, there is uncertainty surrounding their relative efficacy.

OBJECTIVES

To compare the benefits and harms of different treatments for ascites in people with decompensated liver cirrhosis through a network meta-analysis and to generate rankings of the different treatments for ascites according to their safety and efficacy.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, Science Citation Index Expanded, World Health Organization International Clinical Trials Registry Platform, and trials registers until May 2019 to identify randomised clinical trials in people with cirrhosis and ascites.

SELECTION CRITERIA

We included only randomised clinical trials (irrespective of language, blinding, or status) in adults with cirrhosis and ascites. We excluded randomised clinical trials in which participants had previously undergone liver transplantation.

DATA COLLECTION AND ANALYSIS

We performed a network meta-analysis with OpenBUGS using Bayesian methods and calculated the odds ratio, rate ratio, and hazard ratio (HR) with 95% credible intervals (CrI) based on an available-case analysis, according to National Institute of Health and Care Excellence Decision Support Unit guidance.

MAIN RESULTS

We included a total of 49 randomised clinical trials (3521 participants) in the review. Forty-two trials (2870 participants) were included in one or more outcomes in the review. The trials that provided the information included people with cirrhosis due to varied aetiologies, without other features of decompensation, having mainly grade 3 (severe), recurrent, or refractory ascites. The follow-up in the trials ranged from 0.1 to 84 months. All the trials were at high risk of bias, and the overall certainty of evidence was low or very low. Approximately 36.8% of participants who received paracentesis plus fluid replacement (reference group, the current standard treatment) died within 11 months. There was no evidence of differences in mortality, adverse events, or liver transplantation in people receiving different interventions compared to paracentesis plus fluid replacement (very low-certainty evidence). Resolution of ascites at maximal follow-up was higher with transjugular intrahepatic portosystemic shunt (HR 9.44; 95% CrI 1.93 to 62.68) and adding aldosterone antagonists to paracentesis plus fluid replacement (HR 30.63; 95% CrI 5.06 to 692.98) compared to paracentesis plus fluid replacement (very low-certainty evidence). Aldosterone antagonists plus loop diuretics had a higher rate of other decompensation events such as hepatic encephalopathy, hepatorenal syndrome, and variceal bleeding compared to paracentesis plus fluid replacement (rate ratio 2.04; 95% CrI 1.37 to 3.10) (very low-certainty evidence). None of the trials using paracentesis plus fluid replacement reported health-related quality of life or symptomatic recovery from ascites.

FUNDING

the source of funding for four trials were industries which would benefit from the results of the study; 24 trials received no additional funding or were funded by neutral organisations; and the source of funding for the remaining 21 trials was unclear.

AUTHORS' CONCLUSIONS

Based on very low-certainty evidence, there is considerable uncertainty about whether interventions for ascites in people with decompensated liver cirrhosis decrease mortality, adverse events, or liver transplantation compared to paracentesis plus fluid replacement in people with decompensated liver cirrhosis and ascites. Based on very low-certainty evidence, transjugular intrahepatic portosystemic shunt and adding aldosterone antagonists to paracentesis plus fluid replacement may increase the resolution of ascites compared to paracentesis plus fluid replacement. Based on very low-certainty evidence, aldosterone antagonists plus loop diuretics may increase the decompensation rate compared to paracentesis plus fluid replacement.

Severe steatosis induces portal hypertension by systemic arterial hyporeactivity and hepatic vasoconstrictor hyperreactivity in rats

Non-alcoholic fatty liver disease (NAFLD) has become the most prevalent chronic liver disease. The presence of portal hypertension has been demonstrated in NAFLD prior to development of inflammation or fibrosis, and is a result of extrahepatic and intrahepatic factors, principally driven by vascular dysfunction. An increased intrahepatic vascular resistance potentially contributes to progression of NAFLD via intralobular hypoxia. However, the exact mechanisms underlying vascular dysfunction in NAFLD remain unknown. This study investigates systemic hemodynamics and both aortic and intrahepatic vascular reactivity in a rat model of severe steatosis. Wistar rats were fed a methionine-choline-deficient diet, inducing steatosis, or control diet for 4 weeks. In vivo hemodynamic measurements, aortic contractility studies, and in situ liver perfusion experiments were performed. The mean arterial blood pressure was lower and portal blood pressure was higher in steatosis compared to controls. The maximal contraction force in aortic rings from steatotic rats was markedly reduced compared to controls. While blockade of nitric oxide (NO) production did not reveal any differences, cyclooxygenase (COX) blockade reduced aortic reactivity in both controls and steatosis, whereas effects were more pronounced in controls. Effects could be attributed to COX-2 iso-enzyme activity. In in situ liver perfusion experiments, exogenous NO donation or endogenous NO stimulation reduced the transhepatic pressure gradient (THPG), whereas NO synthase blockade increased the THPG only in steatosis, but not in controls. Alpha-1-adrenergic stimulation and endothelin-1 induced a significantly more pronounced increase in THPG in steatosis compared to controls. Our results demonstrate that severe steatosis, without inflammation or fibrosis, induces portal hypertension and signs of a hyperdynamic circulation, accompanied by extrahepatic arterial hyporeactivity and intrahepatic vascular hyperreactivity. The arterial hyporeactivity seems to be NO-independent, but appears to be mediated by specific COX-2-related mechanisms. Besides, the increased intrahepatic vascular resistance in steatosis appears not to be NO-related but rather to vasoconstrictor hyperreactivity.

Invasive Hemodynamic Characterization of the Portal-hypertensive Syndrome in Cirrhotic Rats

This is a detailed protocol describing invasive hemodynamic measurements in cirrhotic rats for the characterization of portal hypertensive syndrome. Portal hypertension (PHT) due to cirrhosis is responsible for the most severe complications in patients with liver disease. The full picture of the portal hypertensive syndrome is characterized by increased portal pressure (PP) due to the increased intrahepatic vascular resistance (IHVR), hyperdynamic circulation, and increased splanchnic blood flow. Progressive splanchnic arterial vasodilation and increased cardiac output with elevated heart rate (HR) but low arterial pressure characterizes the portal hypertensive syndrome. Novel therapies are currently being developed that aim to decrease PP by either targeting IHVR or increased splanchnic blood flow - but side effects on systemic hemodynamics may occur. Thus, a detailed characterization of portal venous, splanchnic, and systemic hemodynamic parameters, including measurement of PP, portal venous blood flow (PVBF), mesenteric arterial blood flow, mean arterial pressure (MAP), and HR is needed for preclinical evaluation of the efficacy of novel treatments for PHT. Our video article provides the reader with a structured protocol for performing invasive hemodynamic measurements in cirrhotic rats. In particular, we describe the catheterization of the femoral artery and the portal vein via an ileocolic vein and the measurement of portal venous and splanchnic blood flow via perivascular Doppler-ultrasound flow probes. Representative results of different rat models of PHT are shown.

Systemic hemodynamic response to terlipressin predicts development of hepatorenal syndrome and survival in advanced cirrhosis

BACKGROUND

The aim of this study was to predict the occurrence of hepatorenal syndrome (HRS) and death in patients with advanced cirrhosis and ascites.

PATIENTS AND METHODS

We retrospectively evaluated 2-year data of 78 patients with cirrhosis and ascites (Child-Pugh B/C: 45/43). The mean arterial pressure (MAP) and cardiac output (CO) were measured in all patients just before administration of 2 mg of terlipressin and 30 min later. Systemic vascular resistance (SVR) was calculated as MAP/CO. ΔMAP, and ΔCO, and ΔSVR were defined as the percentage change of MAP, CO, and SVR, respectively, after terlipressin injection. Plasma renin activity (PRA) and plasma aldosterone were evaluated at baseline. Two multivariate models were used: one excluding (model 1) and one including (model 2) the Model of End-stage Liver Disease score.

RESULTS

Higher ΔSVR, Model of End-stage Liver Disease score, and PRA were related independently to the severity of cirrhosis. Independent predictors of HRS at 12 and 24 months were ΔSVR (models 1/2: P=0.008/0.01 and 0.01/0.02, respectively), ΔCO (models 1/2: P=0.01/0.03 and 0.03/0.04, respectively), and PRA (models 1/2: P=0.04 and model 1: P=0.04, respectively). ΔSVR at 12 and 24 months (models 1/2: P=0.005/0.01 and 0.01/0.03, respectively) and ΔCO at 24 months (models 1/2: P=0.02/0.01, respectively) were related independently to survival. Patient groups with significantly higher probability of HRS and mortality were identified by certain cutoffs of ΔSVR (20.6 and 22.8%, respectively) and ΔCO (-10.6 and -11.8%, respectively). ΔSVR and ΔCO independently predicted survival in patients with the most advanced cirrhosis and infection-related survival.

CONCLUSION

An increase in SVR by at least 20% and a decrease in CO at least 10% in response to terlipressin could predict HRS and mortality in patients with advanced cirrhosis.

Effects of Nuclear Factor-E2-related factor 2/Heme Oxygenase 1 on splanchnic hemodynamics in experimental cirrhosis with portal hypertension

OBJECTIVE

We explored the effects of Nuclear Factor-E2-related factor 2 (Nrf2) and Heme Oxygenase 1 (HO-1) on splanchnic hemodynamics in portal hypertensive rats.

METHODS

Experimental cirrhosis with portal hypertension was induced by intraperitoneal injection of carbon tetrachloride. The expression of proteins was examined by immunoblotting. Hemodynamic studies were performed by radioactive microspheres. The vascular perfusion system was used to measure the contractile response of mesentery arterioles in rats.

RESULTS

Nrf2 expression in the nucleus and HO-1 expression in cytoplasm was significantly enhanced in portal hypertensive rats. Portal pressure, as well as regional blood flow, increased significantly in portal hypertension and can be blocked by tin protoporphyrin IX. The expression of endogenous nitric oxide synthase and vascular endothelial growth factors increased significantly compared to normal rats, while HO-1 inhibition decreased the expression of these proteins significantly. The contractile response of mesenteric arteries decreased in portal hypertension, but can be partially recovered through tin protoporphyrin IX treatment.

CONCLUSIONS

The expression of Nrf2/HO-1 increased in mesenteric arteries of portal hypertensive rats, which was related to oxidative stress. HO-1was involved in increased portal pressure and anomaly splanchnic hemodynamics in portal hypertensive rats.

Role of Transjugular Intrahepatic Portosystemic Shunts in the Management of Hepatopulmonary Syndrome: A Systemic Literature Review

PURPOSE

To evaluate the role of transjugular intrahepatic portosystemic shunt (TIPS) creation in the management of hepatopulmonary syndrome (HPS).

MATERIALS AND METHODS

A MEDLINE (PubMed) search from January 1990 to April 2015 was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The search was restricted to the English language and human subjects. Inclusion criteria were patients with HPS who underwent TIPS creation for any indication. Exclusion criteria was age < 18 years.

RESULTS

Ten studies consisting of 12 patients with HPS were included. Eight patients had very severe HPS, 2 had severe HPS, and 2 had moderate HPS. Transjugular intrahepatic portosystemic shunt creation was technically successful in all patients, without complications. Mean portosystemic pressure gradients before and after the procedure were 18.2 mm Hg (range, 10-30 mm Hg) and 6.5 mm Hg (range, 3-15 mm Hg), respectively. The mean duration of follow-up was 9.3 months (range, 0.75-36 mo). Improvement in oxygenation occurred in 9 patients but was not sustained after 4 months in 2 patients. In the remaining 3 patients, oxygenation remained unchanged; it worsened after 4 months in 1 patient. Four patients underwent liver transplantation. Two patients died of multiple organ dysfunction syndrome and 1 died of sepsis. The remaining patients were alive and well at the time of last follow-up.

CONCLUSIONS

Transjugular intrahepatic portosystemic shunt creation shows promise in the management of HPS. Future prospective studies are warranted.

Portal pressure and blood nitric oxide levels as predictors of outcome in biliary atresia

Aim:

To evaluate the incidence of portal hypertension (PHT) in biliary atresia (BA) patients and to monitor its progress after Kasai portoenterostomy (KP) by measuring nitric oxide (NO) levels in peripheral blood.

Materials and Methods:

A prospective cross-sectional study conducted over a period of 2 years. Intraoperative portal pressure (PP) and blood NO levels at presentation, 1-month, 3-month, and 6-month follow-up, were correlated with clinical and biochemical parameters in BA patients. The mean NO level in age-matched control group was 4.64 ± 2.32 μmol/L.

Results:

Thirty-four BA patients underwent KP over a period of 2 years. The mean age of presentation was 2.7 months (range 1-4 months). The mean intraoperative PP was 21.3 ± 5.4 mmHg. The mean PP in patients aged <60 days, 61–90 days, and >90 days was 18.53 ± 4.45 mmHg, 20.33 ± 3.07 mmHg, and 26.5 ± 5.01 mmHg, respectively. The mean PP in the patients who underwent successful KP was 16.75 ± 3.54 mmHg while for those who continued to have jaundice it was 23.94 ± 4.63 mmHg (P < 0.001). NO levels closely followed the PP as shown by the regression equation NO = 4.79 + 0.64 PP mmHg, R² = 0.69. The mean NO level at presentation was 18.48 ± 4.17 μmol/L and at 1-month, 3-month, and 6-month follow-up was 11.94 ± 5.62 μmol/L, 10.79 ± 6.02 μmol/L, and 9.93 ± 6.53 μmol/L, respectively (P < 0.001). The difference in NO levels was also statistically significant between the patients who cleared jaundice and those with persisting jaundice.

Conclusion:

All BA patients had PHT at presentation. PHT worsens with age and has an adverse effect on outcome of KP. NO levels in blood closely follow PP and higher levels are associated with poor outcome.

The Gastrointestinal Circulation: Physiology and Pathophysiology

The gastrointestinal (GI) circulation receives a large fraction of cardiac output and this increases following ingestion of a meal. While blood flow regulation is not the intense phenomenon noted in other vascular beds, the combined responses of blood flow, and capillary oxygen exchange help ensure a level of tissue oxygenation that is commensurate with organ metabolism and function. This is evidenced in the vascular responses of the stomach to increased acid production and in intestine during periods of enhanced nutrient absorption. Complimenting the metabolic vasoregulation is a strong myogenic response that contributes to basal vascular tone and to the responses elicited by changes in intravascular pressure. The GI circulation also contributes to a mucosal defense mechanism that protects against excessive damage to the epithelial lining following ingestion of toxins and/or noxious agents. Profound reductions in GI blood flow are evidenced in certain physiological (strenuous exercise) and pathological (hemorrhage) conditions, while some disease states (e.g., chronic portal hypertension) are associated with a hyperdynamic circulation. The sacrificial nature of GI blood flow is essential for ensuring adequate perfusion of vital organs during periods of whole body stress. The restoration of blood flow (reperfusion) to GI organs following ischemia elicits an exaggerated tissue injury response that reflects the potential of this organ system to generate reactive oxygen species and to mount an inflammatory response. Human and animal studies of inflammatory bowel disease have also revealed a contribution of the vasculature to the initiation and perpetuation of the tissue inflammation and associated injury response.

Portal hypertension: a review of portosystemic collateral pathways and endovascular interventions

The portal vein is formed at the confluence of the splenic and superior mesenteric vein behind the head of the pancreas. Normal blood pressure within the portal system varies between 5 and 10 mmHg. Portal hypertension is defined when the gradient between the portal and systemic venous blood pressure exceeds 5 mmHg. The most common cause of portal hypertension is cirrhosis. In cirrhosis, portal hypertension develops due to extensive fibrosis within the liver parenchyma causing increased vascular resistance. In addition, the inability of the liver to metabolise certain vasodilators leads to hyperdynamic splanchnic circulation resulting in increased portal blood flow. Decompression of the portal pressure is achieved by formation of portosystemic collaterals. In this review, we will discuss the pathophysiology, anatomy, and imaging findings of spontaneous portosystemic collaterals and clinical manifestations of portal hypertension with emphasis on the role of interventional radiology in the management of complications related to portal hypertension.

Blood flows in tributaries of the portal vein: anatomical and angiographic studies in normal beagle dogs

Liver anatomy, particularly its vascularization, has been investigated in many studies in dogs. Knowledge of blood flow from the main tributaries of the portal vein (PV) is necessary to explain the preferential sites of secondary lesions within the liver based on the site of the initial malignant lesion. How these flows come together was established in an earlier ex vivo study. Here, we highlight in vivo the blood flows from the main PV tributaries and their distribution in the liver of normal dogs. Portographs of the main PV tributaries were obtained in seven dogs after injection of an angiographic contrast medium. After euthanasia, the livers and their portal vascularization (PV and tributaries) were extracted for a comparative corrosion cast study. Flows were demonstrated in the cranial mesenteric vein, caudal mesenteric vein and splenic vein. However, no proper flow could be distinguished for the gastroduodenal and ileocolic veins. All these tributaries primarily supply the lateral liver lobes (right or left). Most of our observations indicate that the cranial mesenteric, caudal mesenteric and splenic veins primarily supply the right lateral lobe and the caudate process of the caudate lobe and secondarily the left lateral lobe, left medial lobe and the quadrate lobe. The two other tributaries (gastroduodenal and ileocolic veins) primarily supply the right lateral lobe and the caudate process of the caudate lobe.

Hepatic hemodynamic changes during liver transplantation: A review

Liver transplantation is performed in the recent decades with great improvements not only technically but also conceptually. However, there is still lack of consensus about the optimal hemodynamic characteristics during liver transplantation. The representative hemodynamic parameters include portal vein pressure, portal vein flow, and hepatic venous pressure gradient; however, there are still others potential valuable parameters, such as total liver inflow and hepatic artery flow. All the parameters are correlated closely and some internal modulating mechanisms, like hepatic arterial buffer response, occur to maintain stable hepatic inflow. To distinguish the unique importance of each hepatic and systemic parameter in different states during liver transplantation, we reviewed the published data and also conducted two transplant cases with different surgical strategies applied to achieve ideal portal inflow and pressure.

Prostacyclin decreases splanchnic vascular contractility in cirrhotic rats

BACKGROUND

Prostacyclin has been shown to increase portal hypertension, but the mechanism is unclear. This study aimed to investigate whether the overproduction of prostacyclin (PGI2) in cirrhosis participates in the splanchnic vascular hyporesponsiveness to vasoconstrictors in cirrhotic rats.

METHODS

Cirrhotic model was created by subcutaneous injection of 60% carbon tetrachloride (CCl4) corn oil solution combined with intermittent drinking of 5% alcohol, and age-matched rats served as controls. The isolated third-generation mesenteric arterioles were used to examine the contractile response to norepinephrine. The changes in vascular diameter were observed under a microscope imaging device. The plasma concentration of 6-ketone-prostaglandin F1alpha (6-keto-PGF1alpha, a stable metabolite of PGI2) was tested via enzyme immunoassays and the expression of cyclooxygenase (COX) in mesenteric arteries was detected by Western blotting.

RESULTS

In parallel with the increase of plasma 6-keto-PGF1alpha, the contractile response of arterioles from cirrhotic rats to norepinephrine was significantly impaired compared with that from controls. Inhibition of PGI2 or protein kinase A with indomethacin or Rp-adenosine 3', 5'-cyclic monophosphothioate (Rp-cAMPS) partially reversed the vascular hypo-contractile response to norepinephrine in arterioles from cirrhotic rats. Indomethacin significantly decreased the plasma 6-keto-PGF1alpha. Furthermore, indomethacin significantly attenuated the effect of Rp-cAMPS on arterioles from cirrhotic rats. COX-1 expression was up-regulated in mesenteric arteries from cirrhotic rats, whereas COX-2 was not detectable in the mesenteric arteries from both cirrhotic and control rats.

CONCLUSION

Enhanced COX-1 expression in cirrhotic rats resulted in elevated PGI2 production which partially contributed to the splanchnic vascular hyporesponsiveness to a vasoconstrictor via the protein kinase A pathway.

Angiogenesis within the duodenum of patients with cirrhosis is modulated by mechanosensitive Kruppel-like factor 2 and microRNA-126

BACKGROUND

The mechanism involved in neovascularization in splanchnic circulation and the main trigger that induces angiogenesis in patients with cirrhosis are not fully recognized.

AIMS

To explore the involvement of flow sensitive lung Kruppel-like factor (KLF2), microRNA-126 (miR-126), angiopoietin-2 (Ang-2) and heme oxygenase-1 (HO-1) in modulation of vascular endothelial growth factor (VEGF) signalling that have a critical effect on growth of new blood vessels.

METHODS

Duodenal biopsies from 22 patients with cirrhosis and 10 controls were obtained during routine endoscopy. The process of angiogenesis was evaluated by a measurement of CD31 concentration, immunodetection of CD34 protein and estimation of capillary densities. Messenger RNA (mRNA) and protein expressions were analysed by real-time PCR, Western blot or ELISA respectively.

RESULTS

Markers of angiogenesis (both, CD31 and CD34) were significantly enhanced in cirrhotic patients. In comparison to healthy controls, levels of Ang-2 and KLF-2 mRNAs as well as Ang-2, KLF-2, HO-1, VEGF protein expressions were considerably increased. Levels of sCD163, a surrogate marker of portal hypertension, correlated with levels of Ang-2, (P = 0.021) and VEGF (P = 0.009). The expression of miR-126, a KLF2-mediated regulator of the VEGF signalling was enhanced in cirrhotic patients.

CONCLUSIONS

Our results demonstrate, for the first time in humans, that neovascularization is induced in duodenal tissue of patients with cirrhosis and proangiogenic factors such as KLF-2, Ang-2, miR-126 and VEGF can contribute to the angiogenesis induced by hemodynamic forces. Thus, cirrhosis-induced blood flow and pressure within splanchnic vessels may be important hemodynamic triggers that initiate the angiogenic signalling cascade.

Medical management of ascites

INTRODUCTION

Ascites is a common complication of advanced cirrhosis that has a significant negative impact on survival. This review updates the reader on the medical management of ascites.

AREAS COVERED

This review explores the pathophysiology of ascites formation in cirrhosis; the current mainstays of medical management (treating the underlying cause of cirrhosis, avoiding nephrotoxic agents, sodium restriction, and combination diuretic therapy); potential novel agents, such as vasoconstrictors and vaptans; and albumin infusions. The literature research covers all aspects of medical management of ascites from the English literature, concentrating on publications from the past 10 years. It provides a thorough understanding of how the correction of pathophysiology of ascites formation helps to improve ascites; knowledge on the monitoring of patients with cirrhosis and ascites receiving medical management, and on prophylaxis against potentially life-threatening complication such as spontaneous bacterial peritonitis; and potential new treatments for ascites.

EXPERT OPINION

Management of patients with cirrhosis and ascites requires careful attention to fluid and electrolyte balance and avoidance of complications. Recognition of refractory ascites allows for the use of second-line treatments. All patients with cirrhosis and ascites should be considered for liver transplantation.

Vascular corrosion casting: analyzing wall shear stress in the portal vein and vascular abnormalities in portal hypertensive and cirrhotic rodents

Vascular corrosion casting is an established method of anatomical preparation that has recently been revived and has proven to be an excellent tool for detailed three-dimensional (3D) morphological examination of normal and pathological microcirculation. In addition, the geometry provided by vascular casts can be further used to calculate wall shear stress (WSS) in a vascular bed using computational techniques. In the first part of this study, the microvascular morphological changes associated with portal hypertension (PHT) and cirrhosis in vascular casts are described. The second part of this study consists of a quantitative analysis of the WSS in the portal vein in casts of different animal models of PHT and cirrhosis using computational fluid dynamics (CFD). Microvascular changes in the splanchnic, hepatic and pulmonary territory of portal hypertensive and cirrhotic mice are described in detail with stereomicroscopic examination and scanning electron microscopy. To our knowledge, our results are the first to report the vascular changes in the common bile duct ligation cirrhotic model. Calculating WSS using CFD methods is a feasible technique in PHT and cirrhosis, enabling the differentiation between different animal models. First, a dimensional analysis was performed, followed by a CFD calculation describing the spatial and temporal WSS distributions in the portal vein. WSS was significantly different between sham/cirrhotic/pure PHT animals with the highest values in the latter. Up till now, no techniques have been developed to quantify WSS in the portal vein in laboratory animals. This study showed for the first time that vascular casting has an important role not only in the morphological evaluation of animal models of PHT and cirrhosis, but also in defining the biological response of the portal vein wall to hemodynamic changes. CFD in 3D geometries can be used to describe the spatial and temporal variations in WSS in the portal vein and to better understand the forces affecting mechanotransduction in the endothelium.

Role of placental growth factor in mesenteric neoangiogenesis in a mouse model of portal hypertension

BACKGROUND & AIMS

Portal hypertension is responsible for the major complications associated with cirrhosis. Angiogenesis has been associated with the pathophysiology of portal hypertension. We investigated the role of placental growth factor (PlGF) and tested the effects of monoclonal antibodies against PlGF (alphaPlGF) in a mouse model of portal hypertension.

METHODS

Using a mouse model of prehepatic portal hypertension, we measured PlGF levels in the mesenteric tissue at different time points. We used knockout mice and alphaPlGF to determine the role of PlGF in the splanchnic hyperdynamic system and portosystemic collateral formation, examining its effects before and after portal hypertension was induced.

RESULTS

PlGF was significantly up-regulated in the mesenteric tissue of mice with portal hypertension. Compared with wild-type animals, the vascular density in the mesentery was reduced in PlGF knockout hypertensive mice, preventing collateral formation and attenuation of mesenteric artery flow without affecting portal pressure. In the prevention study, alphaPlGF showed similar findings as in the knockout study. In mice with portal hypertension, administration of alphaPlGF resulted in a 32% decrease in portal pressure, compared with mice given immunoglobulin G(1) (control).

CONCLUSIONS

Pathologic angiogenesis in the mesenteric tissues of mice with portal hypertension is mediated by PlGF. Blocking PlGF could be an effective strategy for reducing collateral formation and lowering portal pressure; further research into the effects in cirrhosis is warranted.