The molecules: mechanisms of arterial vasodilatation observed in the splanchnic and systemic circulation in portal hypertension

Cardiac Remodeling and Arrhythmic Burden in Pre-Transplant Cirrhotic Patients: Pathophysiological Mechanisms and Management Strategies

Background: Chronic liver disease (CLD) and cirrhosis contribute to approximately 2 million deaths annually, with primary causes including alcohol-related liver disease (ALD), metabolic dysfunction-associated steatotic liver disease (MASLD), and chronic hepatitis B and C infections. Among these, MASLD has emerged as a significant global health concern, closely linked to metabolic disorders and a leading cause of liver failure and transplantation. Objective: This review aims to highlight the interplay between cirrhosis and cardiac dysfunction, emphasizing the pathophysiology, diagnostic criteria, and management of cirrhotic cardiomyopathy (CCM). Methods: A comprehensive literature review was conducted to evaluate the hemodynamic and structural cardiac alterations in cirrhosis. Results: Cirrhosis leads to portal hypertension and systemic inflammation, contributing to CCM, which manifests as subclinical cardiac dysfunction, impaired contractility, and electrophysiological abnormalities. Structural changes, such as increased left ventricular mass, myocardial fibrosis, and ion channel dysfunction, further impair cardiac function. Vasodilation in the splanchnic circulation reduces peripheral resistance, triggering compensatory tachycardia, while the activation of the renin-angiotensin-aldosterone system (RAAS) promotes fluid retention and increases cardiac preload. Chronic inflammation and endotoxemia exacerbate myocardial dysfunction. The 2005 World Congress of Gastroenterology (WCG) and the 2019 Cirrhotic Cardiomyopathy Consortium (CCC) criteria provide updated diagnostic frameworks that incorporate global longitudinal strain (GLS) and tissue Doppler imaging (TDI). Prolonged QT intervals and arrhythmias are frequently observed. Managing heart failure in cirrhotic patients remains complex due to intolerance to afterload-reducing agents, and beta-blockers require careful use due to potential systemic hypotension. The interaction between CCM and major interventions, such as transjugular intrahepatic portosystemic shunt (TIPS) and orthotopic liver transplantation (OLT), highlights the critical need for thorough preoperative cardiac evaluation and vigilant postoperative monitoring. Conclusions: CCM is a frequently underdiagnosed yet significant complication of cirrhosis, impacting prognosis, particularly post-liver transplantation. Early identification using echocardiography and thorough evaluations of arrhythmia risk in cirrhotic patients are critical for optimizing management strategies. Future research should focus on targeted therapeutic approaches to mitigate the cardiac burden in cirrhotic patients and improve clinical outcomes.

The Cross-Talk Between the Heart and the Liver: The Involvement of the Mitral Valve as a Novel Actor upon the Ancient Scene of Liver Cirrhosis

BACKGROUND

To date, little is known about correlations between liver dysfunction and circulatory and cardiac abnormalities (e.g.,: mitral valve, MV) in patients with chronic liver disease (CLD). This study aimed to assess a potential parallelism between liver dysfunction and cardiovascular involvement and identify the factors associated with structural and functional MV disorders.

METHODS

Among 995 patients with CLD, 346 were enrolled and compared with 168 controls without liver disease. According to the degree of liver disease, patients were classified as patients with chronic hepatitis (142) or with liver cirrhosis (Child-A: 70; Child-B: 65; Child-C: 69).

RESULTS

Among the chronic hepatitis group, resting heart rate (HR) and left ventricular (LV) mass were higher than in the control group (p = 0.0008), whereas systemic vascular resistance (SVR) was lower (p = 0.01). Among cirrhotic patients, resting HR, left atrium dimensions/volumes, LV walls thickness, LV mass, cardiac output (CO), isovolumetric relaxation time (IVRT), deceleration time (DT) and prevalence of aortic stenosis were higher than in non-cirrhotic patients (p = 0.02), whereas the e/a ratio and SVR were lower (p = 0.0001). Among Child-B/C, CO, IVRT, DT, prevalence of MV regurgitation and MV calcification score were higher than in the remaining patients (p = 0.02), whereas SVR was lower (p < 0.0001). Among cirrhotic patients with MV regurgitation, Child-Pugh score, liver disease duration, resting HR, left chambers dimensions/mass, CO, IVRT, DT and MV calcification score were higher compared to patients without regurgitation (p < 0.000), whereas mean blood pressure, e/a ratio and SVR were lower (p = 0.008). At multivariate analysis, Child-Pugh score, liver disease duration, left chambers volume/mass and MV calcification score were independently associated with MV regurgitation in cirrhotic patients. Child-Pugh score and MV calcification score strongly correlated in cirrhotic patients (r = 0.68, 95% CI 0.60-0.75, p < 0.0001).

CONCLUSIONS

The magnitude of cardiac morpho/functional abnormalities is associated with the severity of liver dysfunction. Structural and functional MV abnormalities could represent a novel sign of cardiac involvement in liver cirrhosis. The severity and duration of liver disease, the enlargement of cardiac chambers and leaflet calcium accumulation could play a key role.

Pharmacological Interventions for Cirrhotic Ascites: From Challenges to Emerging Therapeutic Horizons

Ascites is the most common complication in patients with decompensated cirrhosis. This condition results in a severely impaired quality of life, excessive healthcare use, recurrent hospitalizations and significant morbidity and mortality. While loop diuretics and mineralocorticoid receptor antagonists are commonly employed for symptom relief, our understanding of their impact on survival remains limited. A comprehensive understanding of the underlying pathophysiological mechanism of ascites is crucial for its optimal management. The renin-angiotensin-aldosterone system (RAAS) is increasingly believed to play a pivotal role in the formation of cirrhotic ascites, as RAAS overactivation leads to a reduction in urine sodium excretion then a decrease in the ability of the kidneys to excrete water. In this review, the authors provide an overview of the pathogenesis of cirrhotic ascites, the challenges associated with current pharmacologic treatments, and the previous attempts to modulate the RAAS, followed by a description of some emerging targeted RAAS agents with the potential to be used to treat ascites.

Recent advances of photoresponsive nanomaterials for diagnosis and treatment of acute kidney injury

Non-invasive imaging in the near-infrared region (NIR) offers enhanced tissue penetration, reduced spontaneous fluorescence of biological tissues, and improved signal-to-noise ratio (SNR), rendering it more suitable for in vivo deep tissue imaging. In recent years, a plethora of NIR photoresponsive materials have been employed for disease diagnosis, particularly acute kidney injury (AKI). These encompass inorganic nonmetallic materials such as carbon (C), silicon (Si), phosphorus (P), and upconversion nanoparticles (UCNPs); precious metal nanoparticles like gold and silver; as well as small molecule and organic semiconductor polymer nanoparticles with near infrared responsiveness. These materials enable effective therapy triggered by NIR light and serve as valuable tools for monitoring AKI in living systems. The review provides a concise overview of the current state and pathological characteristics of AKI, followed by an exploration of the application of nanomaterials and photoresponsive nanomaterials in AKI. Finally, it presents the design challenges and prospects associated with NIR photoresponsive materials in AKI.

Hepatic artery diameter predicts bleeding risk after gastroesophageal varices treatment: a contrast-enhanced CT study

OBJECTIVE

Portal hypertension leads to hepatic artery dilatation and a higher risk of bleeding. We tried to identify the bleeding risk after gastroesophageal varices (GOV) treatment using hepatic artery diameter of contrast-enhanced CT.

METHODS

Retrospective retrieval of 258 patients with cirrhosis who underwent contrast-enhanced CT from January 2022 to May 2023 and endoscopy within one month thereafter at Hainan Affiliated Hospital of Hainan Medical University. Cirrhotic patients before GOV treatment were used as the test cohort (n = 199), and cirrhotic patients after GOV treatment were used as the validation cohort (n = 59). The grading and bleeding risk was classified according to the endoscopic findings. Arterial-phase images of contrast-enhanced CT were used for coronal reconstruction, and the midpoint diameter of the hepatic artery was measured on coronal images. The optimal cutoff value for identifying bleeding risk was analyzed and calculated in the test cohort, and its diagnostic performance was evaluated in the validation cohort.

RESULTS

In the test cohort, hepatic artery diameters were significantly higher in high-risk GOV than in low-risk GOV [4.69 (4.31, 5.56) vs. 3.10 (2.59, 3.77), P < 0.001]. With a hepatic artery diameter cutoff value of 4.06 mm, the optimal area under the operating characteristic curve was 0.940 (95% confidence interval: 0.908-0.972), with a sensitivity of 0.887, a specificity of 0.892, a positive predictive value of 0.904, and a negative predictive value of 0.874 for identifying bleeding risk in the test cohort, while in the validation cohort, the sensitivity was 0.885, specificity was 0.939, positive predictive value was 0.920, and negative predictive value was 0.912.

CONCLUSION

Hepatic artery diameter has high diagnostic performance in identifying bleeding risk after GOV treatment.

Acute Kidney Injury: Medical Causes and Pathogenesis

Acute kidney injury (AKI) is a common clinical syndrome characterized by a sudden decline in or loss of kidney function. AKI is not only associated with substantial morbidity and mortality but also with increased risk of chronic kidney disease (CKD). AKI is classically defined and staged based on serum creatinine concentration and urine output rates. The etiology of AKI is conceptually classified into three general categories: prerenal, intrarenal, and postrenal. Although this classification may be useful for establishing a differential diagnosis, AKI has mostly multifactorial, and pathophysiologic features that can be divided into different categories. Acute tubular necrosis, caused by either ischemia or nephrotoxicity, is common in the setting of AKI. The timely and accurate identification of AKI and a better understanding of the pathophysiological mechanisms that cause kidney dysfunction are essential. In this review, we consider various medical causes of AKI and summarize the most recent updates in the pathogenesis of AKI.

The Role of the Spleen in Portal Hypertension

As liver disease progresses, intrahepatic vascular resistance increases (backward flow theory of portal hypertension) and collateral veins develop. Adequate portal hypertension is required to maintain portal flow into the liver through an increase in blood flow into the portal venous system (forward flow theory of portal hypertension). The splenic artery resistance index is significantly and selectively elevated in cirrhotic patients. In portal hypertension, a local hyperdynamic state occurs around the spleen. Splenomegaly is associated with a poor prognosis in cirrhosis and is caused by spleen congestion and by enlargement and hyperactivation of splenic lymphoid tissue. Hypersplenism can lead to thrombocytopenia caused by increased sequestering and breakdown of platelets in the spleen. The close relationship between the spleen and liver is reflected in the concept of the hepatosplenic axis. The spleen is a regulatory organ that maintains portal flow into the liver and is the key organ in the forward flow theory of portal hypertension. This review summarizes the literature on the role of the spleen in portal hypertension.

Nonselective beta-blocker use is associated with increased hepatic encephalopathy-related readmissions in cirrhosis

BACKGROUND

Hepatic encephalopathy (HE) is a neurocognitive condition in cirrhosis leading to frequent hospitalizations. Nonselective beta-blockers (NSBBs) are the mainstay of pharmacologic treatment in cirrhotic patients. We hypothesized that since NSBBs decrease cardiac output and portal flow, the decreased metabolic filtering process of liver parenchyma may lead to increased HE-related hospitalizations.

AIM

To evaluate the impact of NSBB administration on HE-related readmissions in cirrhotic patients.

METHODS

In this retrospective cohort study, we included 393 patients admitted to Baylor University Medical Center for liver-related portal hypertension indications between January 2013 and July 2018. Independent predictors of the first HE-related readmissions were identified using Cox proportional hazards analysis. The cumulative incidence of the first HE-related readmissions between patients receiving NSBBs and not receiving NSBBs was examined using Fine-Gray modeling to account for the competing risk of death or liver transplantation.

RESULTS

The mean age was 58.1 ± 10.2 years and most patients fell into Child class C (49.1%) or B (43.8%). The median Model for End-Stage Liver Disease-Sodium score was 22 (IQR: 11). The cumulative incidence of the first HE-related readmissions was significantly higher in patients taking NSBBs compared to patients not receiving NSBBs (71.8% vs 41.8%, P < 0.0001). In multivariate analysis, after adjusting for demographics, markers of liver disease severity, selective beta-blocker, lactulose and rifaximin use, NSBB use [Hazard ratio: 1.74 (95%CI: 1.29-2.34)] was independently associated with the first HE-related readmissions over a median follow-up of 3.8 years.

CONCLUSION

NSBB use is independently associated with increased HE-related readmissions in patients with cirrhosis, regardless of liver disease severity.

Update on hepatorenal Syndrome: Definition, Pathogenesis, and management

Hepatorenal syndrome (HRS) is acute kidney injury (AKI) that occurs without evidence of structural abnormalities in the kidneys in patients with liver disease. It is thought to be due to splanchnic vasculature dilatation that is associated with intense increase of renal arteries' tone, leading to renal cortex ischemia and AKI. Nitric oxide, endotoxins, neurohormonal changes, bacterial infection, high serum bilirubin and bile acids are examples for factors contributing to HRS development. Nevertheless, other unknown factors may have role in HRS pathophysiology. Hence, further discussion and research are needed to clearly understand HRS. Plasma volume restoration and vasoconstrictors are the cornerstone of HRS treatment. Others such as octreotide, noradrenaline, infection control, systemic inflammatory response prevention, shunting, and renal replacement therapy are currently used to manage HRS. Liver or combined liver and kidney transplantation is currently the ultimate cure for HRS. This review was written to help in better understanding the pathogenesis, diagnosis, and treatment options for HRS.

Study of the effect of vascular endothelial growth factor (VEGF) C(+405)G (rs2010963) single nucleotide polymorphism on the development of esophageal and gastric varices and risk of variceal bleeding in cirrhotic hepatitis C virus (HCV) patients (VEGF) C(+405)G IN esophageal and gastric varices

Background

HCV infection is a major worldwide cause of chronic liver diseases. Esophageal and gastric varices are common in cirrhotic patients due to concomitant portal hypertension. Variceal hemorrhage is a major decompensating event with high morbidity and mortality. Endothelial dysfunction, occurring in cirrhosis, facilitates the development of liver cirrhosis, portal hypertension and contributes to increased intrahepatic vascular resistance..VEGF family members are major regulators of blood vessel development and function.

Results

The study was conducted on 90 subjects admitted to Tropical Medicine Department, Alexandria Main University Hospital: 30 cirrhotic patients with endoscopically proven varices (group A), 30 cirrhotic patients without varices (group B), and 30 healthy controls (group C). All patients was subjected to detailed history taking and thorough clinical examination, laboratory investigations, ultrasound abdomen, upper gastrointestinal endoscopy, and genotyping for VEGF C(+405)G (rs2010963) by 5′ nuclease assay. The VEGF C(+405)G (rs2010963) GG genotype was associated with higher prevalence of esophageal and gastric varices and higher bleeding risk.

Conclusion

VEGF C(+405)G (rs2010963) is an important genetic determinant of esophageal varices, gastric varices, and correlates with variceal bleeding risk. Genetic testing of this SNP would be useful in prediction of esophageal and gastric varices and bleeding risk.

Management of portal hypertension based on portal hemodynamics

Portal hypertension is most commonly caused by chronic liver disease. As liver damage progresses, portal pressure gradually elevates and hemodynamics of the portal system gradually change. In normal liver, venous returns from visceral organs join the portal trunk and flow into the liver (hepatopetal blood flow). As portal pressure increases due to liver damage, congestion of some veins of the visceral organ occurs (blood flow to and from). Finally, the direction of some veins (the left gastric vein in particular) of the visceral organ change (hepatofugal blood flow) and develop as collateral veins (portosystemic shunt) to reduce portal pressure. Therefore, esophagogastric varices serve as drainage veins for the portal venous system to reduce the portal pressure. In chronic liver disease, as intrahepatic vascular resistance is increased (backward flow theory) and collateral veins develop, adequate portal hypertension is required to maintain portal flow into the liver through an increase of blood flow into the portal venous system (forward flow theory). Splanchnic and systemic arterial vasodilatations increase the blood flow into the portal venous system (hyperdynamic state) and lead to portal hypertension and collateral formation. Hyperdynamic state, especially around the spleen, is detected in patients with portal hypertension. The spleen is a regulatory organ that maintains portal flow into the liver. In this review, surgical treatment, interventional radiology, endoscopic treatment, and pharmacotherapy for portal hypertension (esophagogastric varices in particular) are described based on the portal hemodynamics using schema.

Nitrergic perivascular innervation in health and diseases: Focus on vascular tone regulation

For a long time, the vascular tone was considered to be regulated exclusively by tonic innervation of vasoconstrictor adrenergic nerves. However, accumulating experimental evidence has revealed the existence of nerves mediating vasodilatation, including perivascular nitrergic nerves (PNN), in a wide variety of mammalian species. Functioning of nitrergic vasodilator nerves is evidenced in several territories, including cerebral, mesenteric, pulmonary, renal, penile, uterine and cutaneous arteries. Nitric oxide (NO) is the main neurogenic vasodilator in cerebral arteries and acts as a counter-regulatory mechanism for adrenergic vasoconstriction in other vascular territories. In the penis, NO relaxes the vascular and cavernous smooth muscles leading to penile erection. Furthermore, when interacting with other perivascular nerves, NO can act as a neuromodulator. PNN dysfunction is involved in the genesis and maintenance of vascular disorders associated with arterial and portal hypertension, diabetes, ageing, obesity, cirrhosis and hormonal changes. For example defective nitrergic function contributes to enhanced sympathetic neurotransmission, vasoconstriction and blood pressure in some animal models of hypertension. In diabetic animals and humans, dysfunctional nitrergic neurotransmission in the corpus cavernosum is associated with erectile dysfunction. However, in some vascular beds of hypertensive and diabetic animals, an increased PNN function has been described as a compensatory mechanism to the increased vascular resistance. The present review summarizes current understanding on the role of PNN in control of vascular tone, its alterations under different conditions and the associated mechanisms. The knowledge of these changes can serve to better understand the mechanisms involved in these disorders and help in planning new treatments.

Pathophysiological-based treatments of complications of cirrhosis

Detailed knowledge and understanding of the pathophysiological mechanisms and changes in hepatic and splanchnic function leading to the development of haemodynamic changes and portal hypertension in patients with cirrhosis are essential since it guides the search for targets to ameliorate liver-related abnormalities. Recent research has focused on the gut-liver axis, changes in intestinal permeability, translocation of bacterial products, and inflammation as important drivers of haemodynamic alterations and thereby targets for treatment. Additionally, treatment strategies should focus on microbiotic modulation, antiangiogenics, anti-inflammatory strategies, and modulation of bile acid metabolism. This paper aims to review contemporary pathophysiological-based treatment principles of the major complications of cirrhosis and portal hypertension and future targets for treatment.

Relation between redox homeostasis blood parameters in cirrhotic patients and endothelial dysfunction development

BACKGROUND

Liver is one of the first organs to be exposed to reactive oxygen species (ROS). But the data about the levels of redox homeostasis parameters in the patients with liver cirrhosis (LC) are contradictory. We hypothesized that the levels of malondialdehyde and catalase should change in accordance with the LC severity causing the endothelial dysfunction.

METHODS

In a randomized way with the preliminary stratification by the presence of LC 81 patients and 20 healthy volunteers were examined. To determine the contents of catalase, malondialdehyde, cyclic guanosine monophosphate, endothelin-1, renin, aldosterone, natriuretic peptide, the routine standardized methods were used.

RESULTS

Patients with LC revealed the statistically significant increase of malondialdehyde and decrease of catalase levels in parallel with the increase of cyclic guanosine monophosphate, endothelin-1, renin, aldosterone, natriuretic peptide contents and disease course worsening according to the Child-Pugh criteria. It testifies the huge oxidative stress impact on the organism. Initially, at the stage of LC compensation, it slightly stimulates the activation of antioxidant system, followed by its gradual suppression at the stages of sub- and decompensation. Disorders of redox homeostasis lead to the endothelial dysfunction that becomes the background of extrahepatic comorbid disorders.

CONCLUSIONS

Cirrhotic patients have significant abnormalities in the redox homeostasis, which become the background of the endothelial dysfunction - common trigger mechanism for the syntrophic comorbid diseases and early pathophysiologic symptom of the unfavorable prognosis for such patients.

Mechanisms in fluid retention - towards a mutual concept

Fluid retention is a common and challenging condition in daily clinical practice. The normal fluid homoeostasis in the human body is based on accurately counter-balanced physiological mechanisms. When compromised fluid retention occurs and is seen in pathophysiologically different conditions such as liver cirrhosis, heart and kidney failure, and in preeclampsia. These conditions may share pathophysiological mechanisms such as functional arterial underfilling, which seems to be a mutual element in cirrhosis, cardiac failure, cardiorenal and hepatorenal syndromes, and in pregnancy. However, there are also distinct differences and it is still unclear whether kidney dysfunction or arterial underfilling is the initiating factor of fluid retention or if they happen simultaneously. This review focuses on similarities and differences in water retaining conditions and points to areas where important knowledge is still needed.

The pathophysiology of arterial vasodilatation and hyperdynamic circulation in cirrhosis

Patients with cirrhosis and portal hypertension often develop complications from a variety of organ systems leading to a multiple organ failure. The combination of liver failure and portal hypertension results in a hyperdynamic circulatory state partly owing to simultaneous splanchnic and peripheral arterial vasodilatation. Increases in circulatory vasodilators are believed to be due to portosystemic shunting and bacterial translocation leading to redistribution of the blood volume with central hypovolemia. Portal hypertension per se and increased splanchnic blood flow are mainly responsible for the development and perpetuation of the hyperdynamic circulation and the associated changes in cardiovascular function with development of cirrhotic cardiomyopathy, autonomic dysfunction and renal dysfunction as part of a cardiorenal syndrome. Several of the cardiovascular changes are reversible after liver transplantation and point to the pathophysiological significance of portal hypertension. In this paper, we aimed to review current knowledge on the pathophysiology of arterial vasodilatation and the hyperdynamic circulation in cirrhosis.

Biology of portal hypertension

Portal hypertension develops as a result of increased intrahepatic vascular resistance often caused by chronic liver disease that leads to structural distortion by fibrosis, microvascular thrombosis, dysfunction of liver sinusoidal endothelial cells (LSECs), and hepatic stellate cell (HSC) activation. While the basic mechanisms of LSEC and HSC dysregulation have been extensively studied, the role of microvascular thrombosis and platelet function in the pathogenesis of portal hypertension remains to be clearly characterized. As a secondary event, portal hypertension results in splanchnic and systemic arterial vasodilation, leading to the development of a hyperdynamic circulatory syndrome and subsequently to clinically devastating complications including gastroesophageal varices and variceal hemorrhage, hepatic encephalopathy from the formation of portosystemic shunts, ascites, and renal failure due to the hepatorenal syndrome. This review article discusses: (1) mechanisms of sinusoidal portal hypertension, focusing on HSC and LSEC biology, pathological angiogenesis, and the role of microvascular thrombosis and platelets, (2) the mesenteric vasculature in portal hypertension, and (3) future directions for vascular biology research in portal hypertension.

Decompensated liver cirrhosis and neural regulation of mesenteric vascular tone in rats: role of sympathetic, nitrergic and sensory innervations

We evaluated the possible alterations produced by liver cholestasis (LC), a model of decompensated liver cirrhosis in sympathetic, sensory and nitrergic nerve function in rat superior mesenteric arteries (SMA). The vasoconstrictor response to electrical field stimulation (EFS) was greater in LC animals. Alpha-adrenoceptor antagonist phentolamine and P2 purinoceptor antagonist suramin decreased this response in LC animals more than in control animals. Both non-specific nitric oxide synthase (NOS) L-NAME and calcitonin gene related peptide (CGRP) (8-37) increased the vasoconstrictor response to EFS more strongly in LC than in control segments. Vasomotor responses to noradrenaline (NA) or CGRP were greater in LC segments, while NO analogue DEA-NO induced a similar vasodilation in both experimental groups. The release of NA was not modified, while those of ATP, nitrite and CGRP were increased in segments from LC. Alpha 1 adrenoceptor, Rho kinase (ROCK) 1 and 2 and total myosin phosphatase (MYPT) expressions were not modified, while alpha 2B adrenoceptor, nNOS expression and nNOS and MYPT phosphorylation were increased by LC. Together, these alterations might counteract the increased splanchnic vasodilation observed in the last phases of decompensated liver cirrhosis.

Clinical and pathophysiological consequences of alterations in the microbiome in cirrhosis

Cirrhosis is a major cause of mortality worldwide. Exponential rises in prevalence have been observed secondary to increases in obesity and alcohol consumption. Multiple lines of evidence implicate gut-derived bacteria and bacterial ligands as a central driver of pathogenesis. Recent developments in culture-independent techniques have facilitated a more accurate description of microbiome composition in cirrhosis and led to the description of measures of dysbiosis shown to be associated with disease. More importantly, metagenomic studies are adding to an understanding of the functional contribution of the microbiota and may prove to be a more clinically relevant biomarker than phylogenetic studies. Much like other dysbiotic states such as inflammatory bowel disease, the microbiota in cirrhosis is characterized by a low microbial and genetic diversity. Therapeutic strategies to diminish this process are currently limited to selective intestinal decontamination with antibiotics. This review summarizes the available data and develops a framework for the use of current and future treatment strategies to diminish the consequences of dysbiosis in cirrhosis. Interventional strategies to bind bacterial products in the gut lumen and blood, and modulate the magnitude of host sensing mechanisms remain an unmet clinical need. A greater understanding of the host-microbiota interaction in cirrhosis is of key importance to inform future interventional strategies to diminish the currently escalating burden of the disease.

Arachidonic acid metabolites and endothelial dysfunction of portal hypertension

Increased resistance to portal flow and increased portal inflow due to mesenteric vasodilatation represent the main factors causing portal hypertension in cirrhosis. Endothelial cell dysfunction, defined as an imbalance between the synthesis, release, and effect of endothelial mediators of vascular tone, inflammation, thrombosis, and angiogenesis, plays a major role in the increase of resistance in portal circulation, in the decrease in the mesenteric one, in the development of collateral circulation. Reduced response to vasodilators in liver sinusoids and increased response in the mesenteric arterioles, and, viceversa, increased response to vasoconstrictors in the portal-sinusoidal circulation and decreased response in the mesenteric arterioles are also relevant to the pathophysiology of portal hypertension. Arachidonic acid (AA) metabolites through the three pathways, cyclooxygenase (COX), lipoxygenase, and cytochrome P450 monooxygenase and epoxygenase, are involved in endothelial dysfunction of portal hypertension. Increased thromboxane-A2 production by liver sinusoidal endothelial cells (LSECs) via increased COX-1 activity/expression, increased leukotriens, increased epoxyeicosatrienoic acids (EETs) (dilators of the peripheral arterial circulation, but vasoconstrictors of the portal-sinusoidal circulation), represent a major component in the increased portal resistance, in the decreased portal response to vasodilators and in the hyper-response to vasoconstrictors. Increased prostacyclin (PGI2) via COX-1 and COX-2 overexpression, and increased EETs/heme-oxygenase-1/K channels/gap junctions (endothelial derived hyperpolarizing factor system) play a major role in mesenteric vasodilatation, hyporeactivity to vasoconstrictors, and hyper-response to vasodilators. EETs, mediators of liver regeneration after hepatectomy and of angiogenesis, may play a role in the development of regenerative nodules and collateral circulation, through stimulation of vascular endothelial growth factor (VEGF) inside the liver and in the portal circulation. Pharmacological manipulation of AA metabolites may be beneficial for cirrhotic portal hypertension.

Clinical implications of the hyperdynamic syndrome in cirrhosis

The hyperdynamic syndrome is a late consequence of portal hypertension in cirrhosis. The principal hemodynamic manifestations of the hyperdynamic syndrome are high cardiac output, and increased heart rate and total blood volume, accompanied by reduced total systemic vascular resistance. Pathophysiology involves a complex of humoral and neural mechanisms that can determine hemodynamic changes, and lead to hyperdynamic circulation. In this review we focus our attention on the manifestations of the hyperdynamic syndrome. Some of these are well described and directly related to portal hypertension (varices, ascites, hepatic encephalopathy, and hepatorenal syndrome), while others, such as hepatopulmonary syndrome, portopulmonary hypertension, and cirrhotic cardiomyopathy, are less known as clinical manifestations related to cirrhosis and, therefore, merit further investigation.

Pathophysiology of portal hypertension

Portal hypertension is a major complication of liver disease that results from a variety of pathologic conditions that increase the resistance to the portal blood flow into the liver. As portal hypertension develops, the formation of collateral vessels and arterial vasodilation progresses, which results in increased blood flow to the portal circulation. Hyperdynamic circulatory syndrome develops, leading to esophageal varices or ascites. This article summarizes the factors that increase (1) intrahepatic vascular resistance and (2) the blood flow in the splanchnic and systemic circulations in liver cirrhosis. In addition, the future directions of basic/clinical research in portal hypertension are discussed.

Effects of carvedilol and propranolol on circulatory regulation and oxygenation in cirrhosis: a randomised study

BACKGROUND AND AIMS

Newer studies suggest that carvedilol, a beta-blocker with a moderate anti-alpha-1 activity, is superior to propranolol in reducing the portal pressure and risk of variceal bleeding. The effect on arterial blood pressure is a matter of concern especially in decompensated patients.

AIMS

to assess potential differential effects of beta-blockers and beta-blockers with moderate anti-alpha-1 activity on selected haemodynamic, humoral, and respiratory characteristics in cirrhosis.

METHODS

Patients with cirrhosis and portal hypertension were randomised to receive carvedilol (n=16) or propranolol (n=13). Cardiac, systemic and splanchnic parameters along with oxygen saturation and plasma renin were measured at inclusion and after 3 months.

RESULTS

Arterial blood pressure, heart rate, and cardiac output decreased equally, central circulation time and systemic vascular resistance increased significantly but similarly. Central blood volume, plasma volume and arterial compliance were unaltered. The QTc interval and renin levels decreased in the carvedilol group, however not significantly different from the propranolol group. Arterial oxygen saturation and alveolar arterial oxygen gradient remained constant in both groups. Hepatic venous pressure gradient decreased equally in the carvedilol and propranolol groups (-17% and -20%, non significant).

CONCLUSIONS

Systemic haemodynamics and pulmonary effects of carvedilol and propranolol are modest and this study could not demonstrate any significant difference between the two treatments.

Hyponatraemia and cirrhosis

Hyponatraemia is a common complication of advanced cirrhosis related to an impairment in the renal capacity for eliminating solute-free water, causing a retention of water that is disproportionate to the retention of sodium, thus leading to a reduction in serum sodium concentration and hypo-osmolality. The main pathogenic factor responsible for hyponatraemia is a non-osmotic hypersecretion of arginine vasopressin (AVP) or antidiuretic hormone from the neurohypophysis, related to circulatory dysfunction. Hyponatraemia in cirrhosis is associated with increased morbidity and mortality. Hyponatraemia is also associated with increased morbidity and impaired short-term survival after transplantation. The current standard of care based on restricting fluids to 1-1.5 L/day is rarely effective. Other approaches, such as albumin infusion and the use of vaptans-which act by specifically antagonizing the effects of AVP on the V2 receptors located in the kidney tubules-have been evaluated for their role in the management of hyponatraemia. The short-term treatment with vaptans is associated with a marked increase in renal solute-free water excretion and improvement of hyponatraemia; however their use in patients with end-stage liver disease is limited by hepatotoxic effects of some of these drugs. Long-term administration of vaptans seems to be effective in maintaining the improvement of serum sodium concentration, but the available information is still limited.

[Hepatorenal syndrome]

Hepatorenal syndrome is a severe complication of end-stage liver disease. The pathophysiological hallmark is severe renal vasoconstriction, resulting from peripheral and splanchnic vasodilation as well as activation of renal vasoconstrictor molecules, which induce the effective arterial volume reduction and the functional renal failure. The diagnosis of hepatorenal syndrome is currently based on the exclusion of other causes of renal failure (especially prerenal). Spontaneous bacterial peritonitis is one of the triggering factors and should be sought in all patients with severe liver disease and acute renal failure. Quickly treating patients with parental antibiotics and albumin infusion significantly decreases the risk. The combined use of intravenous albumin, splanchnic and peripheral vasoconstrictor and/or renal replacement therapy sometimes enables a delay until liver transplantation (or combined liver-kidney in selected patients). Transplantation is in fact the only way to improve the long-term prognosis.

The bile acid membrane receptor TGR5: a novel pharmacological target in metabolic, inflammatory and neoplastic disorders

TGR5 is the G-protein-coupled bile acid-activated receptor, found in many human and animal tissues. Considering different endocrine and paracrine functions of bile acids, the current review focuses on the role of TGR5 as a novel pharmacological target in the metabolic syndrome and related disorders, such as diabetes, obesity, atherosclerosis, liver diseases and cancer. TGR5 ligands improve insulin sensitivity and glucose homeostasis through the secretion of incretins. The bile acid/TGR5/cAMP signaling pathway increases energy expenditure in brown adipose tissue and skeletal muscle. Activation of TGR5 in macrophages inhibits production of proinflammatory cytokines and attenuates the development of atherosclerosis. This receptor has been detected in many cell types of the liver where it has anti-inflammatory effects, thus reducing liver steatosis and damage. TGR5 also modulates hepatic microcirculation and fluid secretion in the biliary tree. In cell culture models TGR5 has been linked to signaling pathways involved in metabolism, cell survival, proliferation and apoptosis, which suggest a possible role of TGR5 in cancer development. Despite the fact that TGR5 ligands may represent novel drugs for prevention and treatment of different aspects of the metabolic syndrome, clinical studies are awaited with the perspective that they will complete TGR5 biology and identify efficient and safe TGR5 agonists.

Update on new aspects of the renin-angiotensin system in liver disease: clinical implications and new therapeutic options

The RAS (renin-angiotensin system) is now recognized as an important regulator of liver fibrosis and portal pressure. Liver injury stimulates the hepatic expression of components of the RAS, such as ACE (angiotensin-converting enzyme) and the AT(1) receptor [AngII (angiotensin II) type 1 receptor], which play an active role in promoting inflammation and deposition of extracellular matrix. In addition, the more recently recognized structural homologue of ACE, ACE2, is also up-regulated. ACE2 catalyses the conversion of AngII into Ang-(1-7) [angiotensin-(1-7)], and there is accumulating evidence that this 'alternative axis' of the RAS has anti-fibrotic, vasodilatory and anti-proliferative effects, thus counterbalancing the effects of AngII in the liver. The RAS is also emerging as an important contributor to the pathophysiology of portal hypertension in cirrhosis. Although the intrahepatic circulation in cirrhosis is hypercontractile in response to AngII, resulting in increased hepatic resistance, the splanchnic vasculature is hyporesponsive, promoting the development of the hyperdynamic circulation that characterizes portal hypertension. Both liver fibrosis and portal hypertension represent important therapeutic challenges for the clinician, and there is accumulating evidence that RAS blockade may be beneficial in these circumstances. The present review outlines new aspects of the RAS and explores its role in the pathogenesis and treatment of liver fibrosis and portal hypertension.

Hyponatremia in cirrhosis

Hyponatremia is common in patients with cirrhosis. Portal hypertension, diuretics, large volume paracentesis without albumin, infection, and multiple medications are connected with the development or worsening of hyponatremia. Hyponatremia in cirrhosis, particularly advanced cirrhosis, is a common development.(1) In a population survey of 997 patients with cirrhosis, 486 (49.4%) and 211 (21.6%) had a serum sodium concentration ([Na(+)]) <135 mEq/L and ≤ 130 mEq/L, respectively.(2) Hyponatremia and its severity correlate with the presence of severe complications of cirrhosis such as hepatorenal syndrome, encephalopathy, and spontaneous bacterial peritonitis. The presence of hyponatremia frequently complicates the management of the cirrhotic patient.

Effect of short- and long-term portal hypertension on adrenergic, nitrergic and sensory functioning in rat mesenteric artery

In the present study, we analysed possible alterations in adrenergic, nitrergic and sensory functioning in mesenteric arteries from rats at 1 and 21 months after partial portal vein ligation, and the mechanisms involved in these alterations, if any. For this purpose, we analysed the vasoconstrictor response to EFS (electrical field stimulation) and the effect of the α-antagonist phentolamine, the NOS (nitric oxide synthase) inhibitor L-NAME (N(G)-nitro-L-arginine methyl ester) and the CGRP (calcitonin gene-related peptide) receptor antagonist CGRP-(8-37) in mesenteric segments from ST (short-term; 1 month) and LT (long-term; 21 months) SO (sham-operated) and pre-hepatic PH (portal hypertensive) rats. The vasomotor responses to NA (noradrenaline), the NO donor DEA-NO (diethylamine NONOate) and CGRP were analysed. NA, NO and CGRP releases were measured. Phospho-nNOS (neuronal NOS) expression was studied. The vasoconstrictor response to EFS was decreased in STPH animals. Phentolamine decreased this vasoconstrictor response more strongly in SO animals. Both L-NAME and CGRP-(8-37) increased vasoconstrictor response to EFS more strongly in PH than SO segments. PH did not modify vasomotor responses to NA, DEA-NO or CGRP, but it decreased NA release while increasing those of NO and CGRP. Phospho-nNOS expression was increased by PH. In LTPH, no differences were observed in vasoconstrictor response to EFS, vasomotor responses or neurotransmitter release when compared with age-matched SO animals. In conclusion, the mesenteric innervation may participate in the development of the characteristic hyperdynamic circulation observed in STPH through the joint action of decreased adrenergic influence, and increased nitrergic and sensory innervations influences. The participation of each innervation normalizes under conditions of LTPH.

Hepato-systemic gradient of carbon monoxide in cirrhosis

BACKGROUND AND AIMS

Experimental data suggest that in liver cirrhosis splanchnic and systemic vasculature exhibit marked endothelial Carbon monoxide (CO) overproduction, while recent data demonstrated heme oxygenase (HO) hyperactivity in the liver of rats with cirrhosis. No data are so far available on CO levels in the hepatic veins of cirrhotic patients. We aimed at evaluating whether plasma CO levels differ between systemic (peripheral vein) and hepatic (hepatic vein) circulation in patients with viral cirrhosis with and without ascites.

METHODS

We enrolled 31 consecutive non-smoking in- or outpatients with liver cirrhosis. We measured wedge (occluded, WHVP) and free hepatic venous pressures (FHVP) and hepatic-vein pressure gradient (HVPG) was the calculated. Plasma level of NO and plasma CO concentration were determined both in peripheral vein and in the hepatic vein in cirrhotics.

RESULTS

In cirrhotic patients plasma CO levels were significantly higher in the hepatic vein (16.66±10.71 p.p.m.) than in the peripheral vein (11.71±7.00 p.p.m). Plasma NO levels were significantly higher in peripheral vein (97.02±21.11 μmol/ml) than in the hepatic vein (60.76±22.93 μmol/ml).

CONCLUSIONS

In patients with liver cirrhosis we documented a hepato-systemic CO gradient as inferred by the higher CO values in the hepatic vein than in the peripheral vein. In cirrhotic patients, CO and NO exhibit opposite behavior in the liver, while both molecules show increased values in the systemic circulation. It can be speculated that increased intra-hepatic CO levels might represent a counterbalancing response to reduced NO intra-hepatic levels in human liver cirrhosis.

Therapeutic effect of captopril, pentoxifylline, and cordyceps sinensis in pre-hepatic portal hypertensive rats

BACKGROUND/AIM

Portal hypertension is an important and potentially fatal complication of liver disease whereby cellular and fibrotic alterations manifest to increase portal venous pressure. The aim of this study is to investigate the effect of captopril, pentoxifylline (PTX), and cordyceps sinensis in pre-hepatic portal hypertensive rats.

SETTINGS AND DESIGN

Wistar male rats were divided at random into 3 main groups: the first group: control rats. The second group: sham-operated rats and the third group: prehepatic portal hypertensive rats (PHPHT) induced by regulated pre-hepatic portal vein ligation. After 14 days, Group 3 was subdivided into 5 subgroups. Subgroup (1): portal vein-ligated (PVL) was killed at once; Subgroup (2): received distilled water for 30 days (untreated PVL group); subgroups 3-5 were treated with captopril (60 mg/kg, orally); PTX (100 mg/kg, orally); and C. sinensis (200 mg/kg, orally), respectively, as a single daily dose for 30 days.

PATIENTS AND METHODS

Portal pressure, nitric oxide (NO), antioxidant enzymes, Liver enzymes, and creatinine levels were measured to evaluate the status of the liver state.

RESULTS

Portal vein ligation produced significant increments in liver enzymes, NO, creatinine and portal pressure concomitant with significant decrements in glutathione content and superoxide dismutase activity. Treatment with captopril, PTX, and C. sinensis resulted in a significant reduction in liver enzymes, NO, creatinine and portal pressure and observable increase in antioxidant enzymes.

CONCLUSIONS

captopril, PTX, and C. sinensis have promising effect in controlling PHPHT and reducing hyperdynamic circulatory state through reduction of portal pressure and NO level.

Management of refractory ascites and hepatorenal syndrome

One of the most common manifestations of the development of portal hypertension in the patient with cirrhosis is the appearance of ascites. Once ascites develops, the prognosis worsens and the patient becomes susceptible to complications such as bacterial peritonitis, hepatic hydrothorax, hyponatremia, and complications of diuretic therapy. As the liver disease progresses, the ascites becomes more difficult to treat and many patients develop renal failure. Most patients can be managed by diuretics which, when used correctly, will control the ascites. Spontaneous bacterial peritonitis can be treated effectively, but portends a worse prognosis. Once the ascites becomes refractory to diuretics, liver transplantation is the best option, although use of transjugular intrahepatic portosystemic shunts will control the ascites in many patients. Lastly, the development of hepatorenal syndrome indicates the patient's liver disease is advanced, and transplantation again is the best option. However, use of vasoconstrictors may improve renal function in some patients, helping in their management while they await a liver transplant.

Cirrhosis decreases vasoconstrictor response to electrical field stimulation in rat mesenteric artery: role of calcitonin gene-related peptide

Our study determines alterations in the vasoconstrictor response elicited by electric field stimulation (EFS) in mesenteric arteries from cirrhotic rats treated with CCl(4), and how calcitonin gene-related peptide (CGRP) participates in this response. Vasoconstriction induced by EFS was analysed in the absence and presence of the CGRP receptor antagonist CGRP(8-37) in arterial segments from control and cirrhotic rats. The vasodilator response to exogenous CGRP was tested in both groups of rats, and the interference of the guanylate cyclase inhibitor ODQ or the K(ATP) channel blocker glibenclamide was analysed only in segments from cirrhotic rats. The vasodilator response to the K(ATP) channel opener pinacidil and to 8-bromo-cyclic GMP was tested. The K(ATP) currents were recorded using the patch-clamp technique. Expression of receptor activity-modifying protein 1 (RAMP1), calcitonin receptor-like receptor, Kir 6.1 and sulfonylurea receptor 2B (SUR2B) was also analysed. Release of CGRP and cGMP was measured. The EFS-elicited vasoconstriction was less in segments from cirrhotic rats. The presence of CGRP(8-37) increased the EFS-induced response only in segments from cirrhotic rats. The CGRP-induced vasodilatation was greater in segments from cirrhotic rats, and was inhibited by ODQ or glibenclamide. Both pinacidil and 8-bromo-cyclic GMP induced a stronger vasodilator response in segments from cirrhotic rats. Pinacidil induced greater K(ATP) currents in cirrhotic myocytes. Expression of RAMP1, calcitonin receptor-like receptor, Kir 6.1 and SUR2B was not modified by liver cirrhosis. Liver cirrhosis increased CGRP release, but did not modify cGMP formation. The decreased vasoconstrictor response to EFS in cirrhosis is mediated by increased vasodilator response to CGRP, as well as increased K(ATP) channel gating. This effect of CGRP may play a role in the splanchnic vasodilatation present in liver cirrhosis.

Simultaneous inhibition of TXA(2) and PGI(2) synthesis increases NO release in mesenteric resistance arteries from cirrhotic rats

Our present study examines, in mesenteric resistance arteries, possible vasodilation alterations, and the role of NO and COX (cyclo-oxygenase) derivatives, in cirrhosis. The vasodilator response to acetylcholine was analysed in segments from control and cirrhotic rats. The effects of the non-specific COX inhibitor indomethacin, the specific COX-1 inhibitor SC-560 and the specific COX-2 inhibitor NS-398 were analysed in segments from both groups of rats. NO release was measured, and eNOS [endothelial NOS (NO synthase)], phospho-eNOS, iNOS (inducible NOS), COX-1 and COX-2 protein expression was also analysed. The effects of the TP receptor [TXA2 (thromboxane A(2)) receptor] antagonist SQ 29548, the TXA(2) synthesis inhibitor furegrelate, the PGI(2) (prostaglandin I(2)) synthesis inhibitor TCP (tranylcypromine) or TCP+furegrelate were only determined in segments from cirrhotic rats. The vasodilator response to acetylcholine was higher in segments from cirrhotic rats. Indomethacin, SC-560 and NS-398 did not modify the vasodilator response in control rats; however, indomethacin, NS-398 and TCP+furegrelate increased, whereas SC-560 did not modify and SQ 29548, furegrelate or TCP decreased, the vasodilator response to acetylcholine in cirrhotic rats. NO release was higher in cirrhotic rats. Furegrelate decreased, whereas TCP+furegrelate increased, the NO release in segments from cirrhotic rats. eNOS and COX-1 protein expression was not modified, whereas phosho-eNOS, iNOS and COX-2 protein expression was higher in cirrhotic rats. Therefore the increase in iNOS expression and eNOS activity may mediate increases in endothelial NO release. The COX-2 derivatives TXA(2) and PGI(2) may act simultaneously, producing a compensatory effect that reduces NO release and may limit the hyperdynamic circulation.

Serum sodium predicts prognosis in critically ill cirrhotic patients

BACKGROUND

End-stage liver disease is often complicated by hyponatremia. Cirrhotic patients with hyponatremia admitted to intensive care units (ICUs) have high mortality rates. This study analyzed the outcomes of critically ill cirrhotic patients and identified the prognostic value of serum sodium concentration.

METHODS

One hundred twenty-six consecutive cirrhotic patients admitted to the ICU of a tertiary center during a 1.5-year period were enrolled in this study. Demographic, clinical, and laboratory variables on the first day of ICU admission were prospectively recorded for post hoc analysis.

RESULTS

Overall hospital mortality was 65.1%. Comparing with serum sodium >135 mmol/L, patients with serum sodium <or=135 mmol/L had a greater frequency of ascites, illness severity scores, hepatic encephalopathy, sepsis, renal failure, and in-hospital mortality (55.9% vs. 73.1%, P=0.043). Multiple Cox proportional hazards analysis revealed that serum sodium levels, hepatocellular carcinoma, and sequential organ failure assessment scores on the first day of ICU admission were independent risk factors for 6-month mortality. Cumulative survival rates at 6-month follow-up after hospital discharge differed significantly (P<0.05) between patients with serum sodium >135 mmol/L versus those with serum sodium <or=135 mmol/L.

CONCLUSIONS

Low serum sodium levels in critically ill cirrhotic patients are associated with high complications of liver cirrhosis, in-hospital mortality, and poor short-term prognosis. The serum sodium concentration is important predictor of survival among candidates for liver transplantation. Future research with sequential application of serum sodium may reflect the dynamic aspects of clinical conditions, thus providing complete data for mortality risk.

Doppler ultrasound of hepatic and system hemodynamics in patients with alcoholic liver cirrhosis

OBJECTIVE

The progression of liver cirrhosis eventually increases cardiac output, while blood pressure and systemic vascular resistance are reduced. A complex behavior of portal hemodynamic to hepatic artery and system circulation has not yet been presented. There is a lack in knowledge about the correlation of local and systemic circulation parameters to the degree of liver failure, with respect to presence of ascites and esophageal varices.

PATIENTS AND METHODS

The study sample was 76 patients hospitalized for established alcoholic liver cirrhosis. Patients were divided into groups according to Child-Pugh clinical score; grade A (n = 24), B (n = 18) and C (n = 18). Ascites was found in 28 patients and esophageal varices in 46. Portal vein flow velocity (PVFV), hepatic artery resistance index (HARI), heart and great vessels within mediastinal cavity were assessed with ultrasound devices equipped with spectral Doppler.

RESULTS

Significant differences in mean blood pressure, systemic vascular resistance index (SVRI) minute volume, cardiac index and PVFV were found in the group of patients with the most severe stage (C). In regard to presence of ascites statistically significant difference was observed in elevated mean blood pressure and SVRI. Correlation was found between conjugated HARI to blood pressure and to SVRI.

CONCLUSIONS

In patients with liver cirrhosis there is an inversely reciprocal relationship of conjugated HARI with PVFV, correlating to disease grade. PVFV in cirrhosis decreases and HARI values were over 0.7. Study demonstrated that combining echocardiography with abdominal Doppler ultrasound served as valuable non-invasive diagnostic insight in liver and systemic circulation among different grade of cirrhosis.

Anesthetic management of acute mesenteric ischemia in elderly patients

Ischemic insult to the splanchnic vasculature can jeopardize bowel viability and lead to devastating consequences, including bowel necrosis and gangrene. Although acute mesenteric ischemia (AMI) may occur at any age, the elderly are most commonly affected due to their higher incidence of underlying systemic pathology, most notably atherosclerotic cardiovascular disease. Treatment options include pharmacology-based actions, endovascular, and surgical interventions. AMI remains a life-threatening condition with a mortality rate of 60% to 80%, especially if intestinal infarction has occurred and surgical intervention becomes emergent. Early recognition and an aggressive therapeutic approach are essential if the usually poor outcome is to be improved. Anesthetic management is complex and must account for comorbid disease as well as the patient's presumptive acute deterioration. Blood pressure support typically involves careful, but often massive, fluid resuscitation and may also additionally require pharmacologic support.

Long-term portal hypertension increases the vasodilator response to acetylcholine in rat aorta: role of prostaglandin I2

In the present study, we have analysed both the effect of long-term portal hypertension on the vasomotor response to acetylcholine in rat aorta and the mechanism involved in this response. For this purpose, sham-operated rats and rats with pre-hepatic PH (portal hypertension; triple partial portal vein ligation) were used at 21 months after surgery. The participation of NO and COX (cyclo-oxygenase) derivatives in the vasodilator response elicited by acetylcholine after incubation with L-NAME (NG-nitro-L-arginine methyl ester), indomethacin, SC-560, NS-398, tranylcypromine and furegrelate, was analysed. NO, TXB2 (thromboxane B2) and 6-keto PGF1alpha (prostaglandin F1alpha) release were measured. In addition, SNP (sodium nitroprusside), U-46619, PGI2 and forskolin vasomotor responses were analysed. COX-1 and COX-2 expression was also determined. The acetylcholine-induced vasodilating response was higher in rats with PH. TXA2 and NO release, and SNP and U-46619 sensitivity were similar in both groups. PGI2 release was not modified by portal hypertension, but vasodilator responses to this prostanoid and to forskolin were higher in rats with PH. COX-1 and COX-2 expression remained unmodified by surgery. In conclusion, increased vasodilation to acetylcholine is maintained in long-term PH. Although the participation of endothelial NO remained unmodified, the COX-2 derivative PGI2 does participate through an increased vasodilator response.

Deleterious effects of silymarin on the expression of genes controlling endothelial nitric oxide synthase activity in carbon tetrachloride-treated rat livers

AIMS

Defects in intrahepatic nitric oxide (NO) are attributed to reduced blood flow due to portal hypertension caused by diminished endothelial NO synthase (eNOS) activity. The aim of this study is to identify the therapeutic effects of silymarin on eNOS/NO-related enzymes and hepatic enzymes in carbon tetrachloride (CCl4)-induced cirrhotic rats.

MAIN METHODS

CCl4 treated for 12 weeks was discontinued and then administrated with silymarin daily for 4 weeks. Collagen concentrations were determined by measuring hydroxyproline content. Serum was assayed for hepatic enzymes like alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) activities. NOS activities were measured by oxyhemoglobin oxidation assay, and levels of enzyme expression and phosphorylation were detected by Western-blot analyses.

KEY FINDINGS

Silymarin treatment restored the values for collagen content and ALT and ALP activities when compared to the values with spontaneous resolution following discontinuation of CCl4. CCl4 treatment highly increased eNOS expression and NOS activity in livers, but the phosphorylation was markedly decreased. Silymarin decreased significantly eNOS expression and activity. Expression and/or phosphorylation of enzymes activating eNOS were unchanged (Akt and AMPK) or decreased (PKA) by silymarin. Especially, the expression of caveolin-1, an inhibitor of eNOS was unchanged by CCl4, but its phosphorylation was significantly increased. However, silymarin markedly increased caveolin-1 expression but decreased its phosphorylation to expression.

SIGNIFICANCE

These results suggest that chronic silymarin treatment can improve cirrhosis-induced liver enzyme activities and fibrosis, but may aggravate the hemodynamic eNOS activity, particularly by decreasing eNOS expression and increasing caveolin-1 expression.

Systemic and pulmonary hemodynamics in patients with extrahepatic portal vein obstruction is similar to compensated cirrhotic patients

BACKGROUND

Patients with cirrhosis and portal hypertension exhibit a hyperdynamic circulation manifesting as increased cardiac output, heart rate and plasma volume; and decreased arterial blood pressure, systemic vascular resistance, and pulmonary vascular resistance. It is believed that these changes are related to both hepatocellular dysfunction and portal hypertension. However, the role of portal hypertension per se in producing these changes in circulation has not been clear. Extrahepatic portal vein obstruction (EHPVO), a vascular disorder of the liver characterized by cavernomatous transformation of the main portal vein, is an excellent model to study the role of portal hypertension per se in producing these changes because there is no hepatic dysfunction in EHPVO. The main aim of our study was, therefore, to evaluate alterations of systemic and pulmonary vascular systems in patients with EHPVO and compare them with patients with compensated cirrhosis.

PATIENTS AND METHODS

Consecutive patients of EHPVO, 15 years or older, and past variceal bleeders were studied. For comparison, consecutive patients with compensated cirrhosis and history of variceal bleed, matched for variceal status, and body surface area were included. The hemodynamic studies included the measurements of cardiac index (by Fick's oxygen method), and systemic and pulmonary vascular resistance indices.

RESULTS

Fifteen patients of EHPVO and same number of controls (compensated cirrhotics) were included in the study. The baseline parameters in the two groups were comparable. Both EHPVO patients and cirrhotics had similar values in all the measured systemic and pulmonary hemodynamic parameters. The median (range) cardiac index in EHPVO was 3.8 (2.3-7.7) l min(-1) m(-2), whereas it was 4.4 (2.8-8.9) l min(-1) m(-2) in cirrhosis (P = 0.468). The median (range) systemic vascular resistance index in EHPVO was 1,835 (806-3400) dyne s cm(-5) m(-2), which was similar to that in cirrhotic patients (1,800 [668-3022], P = 0.520). Similarly, the values of median (range) pulmonary vascular resistance index were comparable in the two groups (71 [42-332] vs. 79 [18-428], P = 0.885). A subgroup analysis was done for 8 patients of EHPVO and 8 age-matched compensated cirrhotic patients, which also revealed similar values of cardiac index, cardiac output, systemic vascular resistance index, systemic vascular resistance, pulmonary vascular resistance index, and pulmonary vascular resistance in the two groups.

CONCLUSIONS

EHPVO patients have hyperdynamic circulation manifested by high cardiac index and low systemic and pulmonary vascular resistance indices. These hemodynamic changes are comparable with compensated cirrhotic patients who have similar grade of portal hypertension. This suggests a predominant role of portal hypertension per se in the genesis of systemic and pulmonary hemodynamic alterations.