Acute effects of captopril on systemic and renal hemodynamics and on renal function in cirrhotic patients with ascites

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.

The Renin-Angiotensin System in Liver Disease

The renin-angiotensin system (RAS) is a complex homeostatic entity with multiorgan systemic and local effects. Traditionally, RAS works in conjunction with the kidney to control effective arterial circulation, systemic vascular resistance, and electrolyte balance. However, chronic hepatic injury and resulting splanchnic dilation may disrupt this delicate balance. The role of RAS in liver disease, however, is even more extensive, modulating hepatic fibrosis and portal hypertension. Recognition of an alternative RAS pathway in the past few decades has changed our understanding of RAS in liver disease, and the concept of opposing vs. "rebalanced" forces is an ongoing focus of research. Whether RAS inhibition is beneficial in patients with chronic liver disease appears to be context-dependent, but further study is needed to optimize clinical management and reduce organ-specific morbidity and mortality. This review presents the current understanding of RAS in liver disease, acknowledges areas of uncertainty, and describes potential areas of future investigation.

Association of Renin-Angiotensin System Inhibition With Liver-Related Events and Mortality in Compensated Cirrhosis

BACKGROUND & AIMS

While renin-angiotensin system inhibition lowers the hepatic venous gradient, the effect on more clinically meaningful endpoints is less studied. We aimed to quantify the relationship between renin-angiotensin system inhibition and liver-related events (LREs) among adults with compensated cirrhosis.

METHODS

In this national cohort study using the Optum database, we quantified the association between angiotensin-converting enzyme (ACE) inhibitor or angiotensin-receptor blocker (ARB) use and LREs (hepatocellular carcinoma, liver transplantation, ascites, hepatic encephalopathy, or variceal bleeding) among patients with cirrhosis between 2009 and 2019. Selective beta-blocker (SBB) users served as the comparator group. We used demographic and clinical features to calculate inverse-probability treatment weighting-weighted cumulative incidences, absolute risk differences, and Cox proportional hazard ratios.

RESULTS

Among 4214 adults with cirrhosis, 3155 were ACE inhibitor/ARB users and 1059 were SBB users. In inverse probability treatment weighting-weighted analyses, ACE inhibitor/ARB (vs SBB) users had lower 5-year cumulative incidence (30.6% [95% confidence interval (CI), 27.8% to 33.2%] vs 41.3% [95% CI, 34.0% to 47.7%]; absolute risk difference, -10.7% [95% CI, -18.1% to -3.6%]) and lower risk of LREs (adjusted hazard ratio [aHR], 0.69; 95% CI, 0.60 to 0.80). There was a dose-response relationship: compared with SBB use, ACE inhibitor/ARB prescriptions ≥1 defined daily dose (aHR, 0.65; 95% CI, 0.56 to 0.76) were associated with a greater risk reduction compared with <1 defined daily dose (aHR, 0.87; 95% CI, 0.71 to 1.07). Results were robust across sensitivity analyses such as comparing ACE inhibitor/ARB users with nonusers and as-treated analysis.

CONCLUSIONS

In this national cohort study, ACE inhibitor/ARB use was associated with significantly lower risk of LREs in patients with compensated cirrhosis. These results provide support for a randomized clinical trial to confirm clinical benefit.

Effects of renin-angiotensin inhibitors on renal function and the clinical course in patients with decompensated cirrhosis

Patients with decompensated cirrhosis are at risk of developing acute kidney injury (AKI). Studies have suggested that inhibition of the Renin-Angiotensin System (RAS) has certain nephro- and hepatoprotective effects in patients with compensated liver disease. This study aimed to investigate the clinical impact of RAS-Inhibitors in individuals with decompensated liver cirrhosis. Overall, 1181 consecutive hospitalized patients with ascites that underwent paracentesis were considered for this retrospective study. In total, 667 patients with decompensated cirrhosis fulfilled the inclusion criteria and were finally analyzed. RAS-Inhibitor intake was documented in 41 patients (7%). First, 28-day incidences of AKI and grade III AKI of all patients with RAS-Inhibitors were compared to those without intake. Afterwards, propensity score matching was conducted in a 3:1 manner. Here, incidence of further renal endpoints such as need of hemodialysis were analyzed in detail. In the unmatched setting, intake of RAS-Inhibitors was not associated with an increased 28 day-incidence of AKI (P = 0.76) or LTx-free survival (P = 0.60). However, 28 day-incidence of grade III AKI was significantly lower in patients with RAS-Inhibitor intake (P < 0.001). In the matched setting, 28 day-incidence of AKI did not differ (P = 0.81), while grade III AKI was significantly less frequent in the RAS-Inhibitor group (P < 0.001). Need for hemodialysis was also significantly lower in patients with RAS-Inhibitors (P = 0.03) and LTx-free survival was comparable between both groups (P = 0.52). Thus, this study suggests that intake of RAS-Inhibitors is associated with decreased incidences of grade III AKI and need of hemodialysis in patients with decompensated liver disease.

Austrian consensus on the diagnosis and management of portal hypertension in advanced chronic liver disease (Billroth IV)

The Billroth IV consensus was developed during a consensus meeting of the Austrian Society of Gastroenterology and Hepatology (ÖGGH) and the Austrian Society of Interventional Radiology (ÖGIR) held on the 26th of November 2022 in Vienna.Based on international recommendations and considering recent landmark studies, the Billroth IV consensus provides guidance regarding the diagnosis and management of portal hypertension in advanced chronic liver disease.

Management of the major complications of cirrhosis: Beyond guidelines

Along with a growing understanding of the pathophysiology of cirrhosis and its complications, new therapies and management strategies have emerged in recent years. Many of these advances have helped inform the current EASL clinical practice guidelines¹ on the management of some of the key complications of cirrhosis, such as ascites, variceal bleeding and infection. However, there are still some aspects of management where the evidence base is less clear, and/or where opinions amongst practitioners remain divided. Some of these more controversial areas are explored in this section, wherein we present evidence culminating in a suggested management approach based on expert opinion and extending beyond the current guidelines.

Pathways of hepatic and renal damage through non-classical activation of the renin-angiotensin system in chronic liver disease

In liver cirrhosis, renin-angiotensin system (RAS) activation sustains renal sodium retention and hepatic fibrogenesis. New information has recently enlivened the traditional concept of RAS. For instance, renin and prorenin bind their ubiquitous receptors, resulting in the local production of angiotensin (Ang) II; increased serum calcium and calcimimetic agents, through stimulation of extracellular calcium-sensing receptors (CaSR), blunt renin production and lead to natriuretic effects in human and experimental cirrhosis. Alongside systemic production, there is Ang II tissue production within various organs through RAS enzymes different from angiotensin-converting enzyme (ACE), that is chymase, tissue plasminogen activator and several cathepsins. In experimental cirrhosis, inhibition of chymase leads to natriuretic and hepatic antifibrotic effects, without changes in systemic haemodynamics. In the kidney, local RAS coordinates proximal and distal tubular sodium reabsorption. However, renalase, whose plasma and tissue levels are severely altered in experimental cirrhosis, degrades systemic and renal tubule catecholamines, antagonizing the effects of renal RAS. Angiotensinogen-derived natriuretic and vasodilating peptides (Ang1-9, Ang1-7, Ang3-8) and their receptors have been described. Receptor agonists or antagonists are available to affect portal hypertension and sodium retention in cirrhosis. ACE2-dependent generation of Ang1-7 may inhibit experimental liver fibrosis. inhibition of Ang1-7 clearance by means of neprilysin blockade has portal hypotensive and natriuretic effects. Ang1-12, whose production renin does not regulate, is converted to several different angiotensin peptides via chymase. Finally, Ang II behaves as either an antinatriuretic or a natriuretic agent, based on the tissue content of AT₁ R and AT₂ R receptors, their ratio being prone to pharmacological modulation.

Austrian consensus guidelines on the management and treatment of portal hypertension (Billroth III)

The Billroth III guidelines were developed during a consensus meeting of the Austrian Society of Gastroenterology and Hepatology (ÖGGH) and the Austrian Society of Interventional Radiology (ÖGIR) held on 18 February 2017 in Vienna. Based on international guidelines and considering recent landmark studies, the Billroth III recommendations aim to help physicians in guiding diagnostic and therapeutic strategies in patients with portal hypertension.

Review article: advances in the management of patients with cirrhosis and portal hypertension-related renal dysfunction

BACKGROUND

In cirrhosis, portal hypertension is associated with a spectrum of renal dysfunction that has significant implications for morbidity and mortality.

AIM

To discuss recent progress in the patho-physiological mechanisms and therapeutic options for portal hypertension-related renal dysfunction.

METHODS

A literature search using Pubmed was performed.

RESULTS

Portal hypertension-related renal dysfunction occurs in the setting of marked neuro-humoral and circulatory derangement. A systemic inflammatory response is a pathogenetic factor in advanced disease. Such physiological changes render the individual vulnerable to further deterioration of renal function. Patients are primed to develop acute kidney injury when exposed to additional 'hits', such as sepsis. Recent progress has been made regarding our understanding of the aetiopathogenesis. However, treatment options once hepatorenal syndrome develops are limited, and prognosis remains poor. Various strategies to prevent acute kidney injury are suggested.

CONCLUSION

Prevention of acute kidney injury in high risk patients with cirrhosis and portal hypertension-related renal dysfunction should be a clinical priority.

Comparative randomized study on efficacy of losartan versus propranolol in lowering portal pressure in decompensated chronic liver disease

OBJECTIVE

This study aimed to compare the efficacy of losartan, an angiotensin II receptor antagonist, with propranolol on portal hypertension in patients with decompensated chronic liver disease.

METHODS

In all, 30 patients with Child-Pugh B cirrhosis and large varices without any prior therapy for portal hypertension were randomized to either losartan (n = 15) or propranolol (n = 15). Clinical, biochemical and hemodynamic parameters including hepatic venous pressure gradient (HVPG), wedged hepatic venous pressure (WHVP), mean arterial blood pressure (MABP) and free hepatic venous pressure (FHVP) were measured at baseline and after 4-week therapy. Patients with HVPG < 12 mmHg were regarded as responders.

RESULTS

An equal number of responders were seen in both groups (6/15, 40.0%). The reduction of WHVP and HVPG was greater in the losartan group than in the propranolol group, although no significant differences between them were found. Heart rate decreased more in the propranolol arm than in the losartan arm (P < 0.01); however, no correlation between the decrease of heart rate and the reduction of HVPG was observed. One patient in the losartan group, although a responder, had gastrointestinal bleeding 2 months after the drug administration, but the varices were small under endoscopy and did not require definitive therapy. The fall of MABP was greater with losartan, with no statistical difference between the two groups.

CONCLUSION

The effect of losartan was comparable to propranolol in reducing portal pressure in decompensated Child-Pugh B chronic liver disease.

Austrian consensus on the definition and treatment of portal hypertension and its complications (Billroth II)

In November 2004, the Austrian Society of Gastroenterology and Hepatology (ÖGGH) held for the first time a consensus meeting on the definitions and treatment of portal hypertension and its complications in the Billroth-Haus in Vienna, Austria (Billroth I-Meeting). This meeting was preceded by a meeting of international experts on portal hypertension with some of the proponents of the Baveno consensus conferences (http://www.oeggh.at/videos.asp). The consensus itself is based on the Baveno III consensus with regard to portal hypertensive bleeding and the suggestions of the International Ascites Club regarding the treatment of ascites. Those statements were modified by new knowledge derived from the recent literature and also by the current practice of medicine as agreed upon by the participants of the consensus meeting. In October 2011, the ÖGGH organized the second consensus meeting on portal hypertension and its complications in Vienna (Billroth II-Meeting). The Billroth II-Guidelines on the definitions and treatment of portal hypertension and its complications take into account the developments of the last 7 years, including the Baveno-V update and several key publications.

Pathophysiology of portal hypertension and its clinical links

Portal hypertension is a major cause of morbidity and mortality in patients with liver cirrhosis. Intrahepatic vascular resistance due to architectural distortion and intrahepatic vasoconstriction, increased portal blood flow due to splanchnic vasodilatation, and development of collateral circulation have been considered as major factors for the development of portal hypertension. Recently, sinusoidal remodeling and angiogenesis have been focused as potential etiologic factors and various researchers have tried to improve portal hypertension by modulating these new targets. This article reviews potential new treatments in the context of portal hypertension pathophysiology concepts.

The role of the renin-angiotensin system in liver fibrosis

Hepatic fibrosis, which is characterized by progressive inflammation and deposition of extracellular matrix components, is a common response to chronic liver disease. Hepatic fibrogenesis is a dynamic process that involves several liver cell types including hepatic stellate cells and Kupffer cells. In addition, recent evidence indicates that bile duct epithelial cells (i.e. cholangiocytes) also participate in the progression of biliary fibrosis that is observed during chronic cholestatic liver diseases, such as primary sclerosing cholangitis. To date, there are no effective treatments for hepatic fibrosis. Several recent studies have demonstrated that the renin-angiotensin system (RAS) plays a key role in hepatic fibrosis. Therapies targeting the RAS may represent a promising paradigm for the prevention and treatment of hepatic fibrosis in the setting of chronic liver disease. In this review, we provide a comprehensive update on the role of RAS in the pathogenesis of hepatic fibrosis in both animal models and human studies. We will discuss the profibrotic mechanisms activated by the RAS and the cell types involved. Studies that have utilized angiotensin receptor blockers (ARBs) and angiotensin-converting enzyme (ACE) inhibitors to modulate the RAS in order to ameliorate hepatic fibrosis will also be discussed. Although the cumulative evidence supports the potential for the use of ARBs and ACE inhibitors as treatment for hepatic fibrosis, extensive studies of the effectiveness of RAS therapeutics are necessary in patients with chronic liver disease.

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.

Renin-angiotensin-aldosterone inhibitors in the reduction of portal pressure: a systematic review and meta-analysis

BACKGROUND & AIMS

Renin-angiotensin-aldosterone antagonists [ACE inhibitors (ACEi), angiotensin receptor blockers (ARB), aldosterone antagonists (AA)] are potential therapies for portal hypertension. We evaluated the efficacy and safety of RAAS inhibitors in hepatic venous pressure gradient (HVPG) reduction.

METHODS

We included full-text controlled trials in patients with cirrhosis and portal hypertension. The primary outcome was mean change in HVPG between treatment and control. Two independent reviewers performed trial selection and quality assessment. An individual patient meta-analysis based on the data of three studies was performed.

RESULTS

From 193 citations, 19 controlled trials (n=678) were included. When compared to placebo, ARB/ACEi resulted in significant HVPG reduction. The best quality trials compared ARB/ACEi to beta-blockers (BB). Pooled individual patient data for three of four of these trials showed that BB decreased the HVPG more than ARB/ACEi. In patients with Child Pugh A cirrhosis, the HVPG reduction with ARB/ACEi (-17%; 95% CI: -28 to -6), was similar to that of BB (-21%; 95% CI: -32 to -9). Significant variation in the comparison groups of AA trials precluded pooling. There was no difference in adverse events in any group but selected studies noted adverse hemodynamic effects in decompensated patients on ARB/ACEi.

CONCLUSIONS

ARB/ACEi reduce portal pressure in patients with Child Pugh A cirrhosis without adverse events. The efficacy and safety in this group may be secondary to a targeted effect on the local hepatic RAAS system, as compared to decompensated patients who risk hypotension and renal insufficiency due to activation of the systemic RAAS. Further studies should determine the potential of these drugs as an alternative or adjunct to BB.

Liver disease and the renin-angiotensin system: recent discoveries and clinical implications

The renin-angiotensin system (RAS) is a key regulator of vascular resistance, sodium and water homeostasis and the response to tissue injury. Historically, angiotensin II (Ang II) was thought to be the primary effector peptide of this system. Ang II is produced predominantly by the effect of angiotensin converting enzyme (ACE) on angiotensin I (Ang I). Ang II acts mainly through the angiotensin II type-1 receptor (AT(1)) and, together with ACE, these components represent the 'classical' axis of the RAS. Drug therapies targeting the RAS by inhibiting Ang II formation (ACE inhibitors) or binding to its receptor (angiotensin receptor blockers) are now in widespread clinical use and have been shown to reduce tissue injury and fibrosis in cardiac and renal disease independently of their effects on blood pressure. In 2000, two groups using different methodologies identified a homolog of ACE, called ACE2, which cleaves Ang II to form the biologically active heptapeptide, Ang-(1-7). Conceptually, ACE2, Ang-(1-7), and its putative receptor, the mas receptor represent an 'alternative' axis of the RAS capable of opposing the often deleterious actions of Ang II. Interestingly, ACE inhibitors and angiotensin receptor blockers increase Ang-(1-7) production and it has been proposed that some of the beneficial effects of these drugs are mediated through upregulation of Ang-(1-7) rather than inhibition of Ang II production or receptor binding. The present review focuses on the novel components and pathways of the RAS with particular reference to their potential contribution towards the pathophysiology of liver disease.

AT1 receptor antagonist Candesartan in selected cirrhotic patients: effect on portal pressure and liver fibrosis markers

BACKGROUND/AIMS

The renin-angiotensin system plays an important role in hepatic fibrogenesis and in portal hypertension. To examine the long-term effects of Candesartan cilexetil, an angiotensin type 1 (AT1) receptor blocker, on portal-systemic haemodynamics and on liver fibrosis.

METHODS

Forty-seven compensated Child A and Child B (8) cirrhotic patients were randomly assigned to receive Candesartan cilexetil, 8 mg/d (N.24) and no treatment (N.23) for 1 year. Portal-systemic haemodynamic parameters, serological levels of procollagen (PIIINP), hyaluronic acid (HA) and transforming growth factor beta 1 (TGFbeta1) were assessed at baseline and after 12 months.

RESULTS

No patients discontinued or decreased the drug. The hepatic venous pressure gradient (HVPG) decreased significantly in treated patients (-8.4%+/-2.4) with a reduction >20% in 25% of cases vs+5.6%+/-2.9 in the untreated group. HA plasma levels decreased significantly in Candesartan treated patients in whom HVPG diminished and rose in untreated patients in whom HVPG increased.

CONCLUSIONS

In selected cirrhotic patients, pharmacological inhibition of the AT1 receptor is well tolerated and induced a mild reduction of portal pressure. This haemodynamic effect might be related to liver fibrogenesis activity.

Inappropriately low angiotensin II generation: a factor determining reduced kidney function and survival in patients with decompensated cirrhosis

BACKGROUND/AIMS

Angiotensin II contributes to the post-glomerular arteriolar vasoconstriction which maintains the glomerular filtration rate (GFR) in renal hypoperfusion. To explore whether depressed angiotensin II generation, due to reduced angiotensinogen production or low angiotensin-converting enzyme (ACE) levels, could impair kidney function in advanced cirrhosis.

METHODS

We studied and prospectively followed up 21 diuretic-free ascitic cirrhotic patients, through these determinations: plasma levels of active renin (AR), renin activity (PRA), angiotensin II, ACE and aldosterone; renal clearances of sodium, inulin and para-aminohippurate; antipyrine clearance. Fifteen healthy subjects were also studied.

RESULTS

GFR distribution was bimodal, 10 patients had low GFR values (l-GFR group) and 11 had normal-GFR values (n-GFR group) (below and above 105 ml/min per 1.73 m(2) body surface area). Antipyrine clearance and Child-Pugh score did not differ in the two patient groups. l-GFR group had higher AR and PRA values, lower ACE levels and a significantly higher AR/Angiotensin II ratio than n-GFR group (all P<0.01). All 21 patients showed increased values of the AR/PRA ratio, i.e. subnormal angiotensinogen levels (P<0.03). The 18-month survival rates of l-GFR and n-GFR groups were 20 and 81% (P<0.02).

CONCLUSIONS

Low-GFR cirrhotic patients had a worse survival rate associated with more severe contraction of the effective arterial blood volume, higher AR/Angiotensin II ratio and lower ACE levels.

Effects of long-term Irbesartan in reducing portal pressure in cirrhotic patients: comparison with propranolol in a randomised controlled study

BACKGROUND/AIMS

The role of angiotensin II (AT-II) type I receptor antagonists in the treatment of portal hypertension remains controversial. We tested the efficacy of Irbesartan (Irb) vs. Propranolol (Pro) in reducing portal pressure and evaluated its systemic haemodynamic effects.

METHODS

Thirty-four patients were randomly assigned to receive either Irb 300 mg/day (19 patients) or Pro 40-120 mg/day (15 patients) for 2 months.

RESULTS

Irb was discontinued in five patients (26%). No major side effect occurred in the Pro group. On an average, the portal pressure gradient decreased significantly more in the Pro than in the Irb group (median -19.5%, range -11/-31% vs. -4.8%, +2.5/-10%, P<0.001). A clinically significant decrease was seen in one (7%) of the patients given Irb vs. five (33%) given Pro (P<0.02). The fall in mean arterial pressure was significantly higher with Irb than with Pro (median -29%, range -15/-45% vs. -4.9%, +8/-19%, P<0.02). Irb significantly modified the blood creatinine clearance (median -29 ml/m, range +9/-61 ml/m, -30, -24/-35% P<0.0001 vs. basal).

CONCLUSIONS

Irb offers no advantage over Pro in the control of portal hypertension. Moreover, its therapeutic profile is limited by important side effects.

Nitric oxide mediates the reduced vasoconstrictor response to angiotensin II in patients with preascitic cirrhosis

BACKGROUND/AIMS

Altered vascular responses to vasopressor agents contribute to the pathogenesis of the circulatory dysfunction in cirrhosis. This study aims to assess the role of endogenous nitric oxide (NO) in the reduced vascular responsiveness to angiotensin II (ANG-II) in eight patients with preascitic cirrhosis compared with eight age- and sex-matched healthy controls.

METHODS

Forearm blood flow (FBF) responses to sub-systemic, locally-active intra-brachial infusions of ANG-II were measured using venous occlusion plethysmography before and during the application of an 'NO-clamp', a balanced co-infusion of L-N(G)-monomethyl-arginine (a selective NO synthase inhibitor) and sodium nitroprusside (an exogenous NO donor) to block endogenous NO production and restore normal NO-mediated basal blood flow, respectively.

RESULTS

Before applying the 'NO-clamp', ANG-II caused dose-dependent reductions of FBF in both groups (P<0.001) that were significantly attenuated in the cirrhotic patients (P=0.012). In the presence of the 'NO-clamp', the ANG-II-mediated vasoconstriction was enhanced in cirrhotic patients (P<0.01), unchanged in controls, and now similar in both groups.

CONCLUSIONS

This study confirms that vasoconstriction to ANG-II is reduced in patients with preascitic cirrhosis, and suggests that this is principally due to enhanced NO generation mediated by ANG-II.

Update on ascites and hepatorenal syndrome

Ascites is the most common complication occurring during liver cirrhosis. Even if a significant decrease in renal clearance may be observed in the first step of chronic active liver disease, renal impairment, at times complicated by the typical signs of hepatorenal syndrome, occurs only in patients with ascites, especially when tense and refractory. Experimental and clinical data seem to suggest a primary sodium and water retention in the pathogenesis of ascites, in the presence of an intrahepatic increase of hydrostatic pressure, which, by itself, physiologically occurs during digestion. Abnormal sodium and water handling leads to plasma volume expansion, followed by decreased peripheral vascular resistance and increased cardiac output. This second step is in agreement with the peripheral arterial vasodilation hypothesis, depicted by an increase in total blood volume, but with a decreased effective arterial blood volume. This discrepancy leads to the activation of the sympathetic nervous and renin-angiotensin-aldosterone systems associated with the progressive activation of the renal autacoid systems, especially, that of the arachidonic acid. During advanced cirrhosis, renal impairment becomes more sustained and renal autacoid vasodilating substances are less available, possibly due to a progressive exhaustion of these systems. At the same time ascites becomes refractory inasmuch as it is no longer responsive to diuretic treatment. Various pathogenetic mechanisms leading to refractory ascites are mentioned. Finally, several treatment approaches to overcome the reduced effectiveness of diuretic therapy are cited. Paracentesis, together with simultaneous administration of human albumin or other plasma expanders is the main common approach to treat refractory ascites and to avoid a further decrease in renal failure. Other effective tools are: administration of terlipressin together with albumin, implantation of the Le Veen shunt, surgical porto-systemic shunting or transjugular intrahepatic portosystemic stent-shunt, or orthotopic liver transplantation, according to the conditions of the individual patient.

Randomized comparison of long-term losartan versus propranolol in lowering portal pressure in cirrhosis

BACKGROUND & AIMS

It has been suggested that losartan, an angiotensin II (A-II) type 1 receptor blocker, may have a pronounced portal pressure reducing effect, far greater than that of propranolol. This randomized controlled trial compared the hemodynamic and renal effects of continued 6-week administration of losartan (n = 25) vs. propranolol (n = 15) in portal hypertensive patients with cirrhosis treated endoscopically after a variceal bleeding episode.

METHODS

Hepatic venous pressure gradient (HVPG), systemic hemodynamics, renal function, and vasoactive factors were measured before and at 6 weeks of treatment.

RESULTS

Losartan did not reduce HVPG (-2% +/- 12%, NS) but significantly decreased mean arterial pressure (MAP, -8% +/- 10%, P = 0.001). On the contrary, propranolol significantly reduced HVPG (-10% +/- 11%, P = 0.003) and cardiac output (-16% +/- 12%, P = 0.001) but did not modify MAP (2.5% +/- 10%, NS). Losartan increased A-II levels, reduced aldosterone, and decreased glomerular filtration rate (GFR) in Child B patients. Propranolol did not modify renal function. Adverse events related to therapy were mild and similar in both groups.

CONCLUSIONS

Unlike propranolol, long-term losartan administration does not significantly reduce HVPG in patients with cirrhosis treated after a variceal bleeding episode, and it caused hypotension and reduced GFR in patients with moderate liver failure. Therefore, losartan is not an alternative to propranolol in preventing variceal rebleeding.

Drug treatment for bleeding oesophageal varices

At the time of diagnosis of cirrhosis, varices are present in about 60% of decompensated and 30% of compensated patients. The risk factors for the first episode of variceal bleeding in cirrhotic patients are the severity of liver dysfunction, a large size of the varices and the presence of endoscopic red colour signs, but only a third of patients who suffer variceal haemorrhage demonstrate the above risk factors. The only treatment that does not require sophisticated equipment or the skills of a specialist, and is immediately available, is vasoactive drug therapy. Hence, drug therapy should be considered to be the initial treatment of choice and can be administered while the patient is transferred to hospital, as has been done in one recent study. Moreover, drug therapy is no longer considered to be only a 'stop-gap' therapy until definitive endoscopic therapy is performed. Several recent trials have reported an efficacy similar to that of emergency sclerotherapy in the control of variceal bleeding. Furthermore, recent evidence suggests that those patients with high variceal or portal pressure are likely to continue to bleed or re-bleed early, implying that prolonged therapy lowering the portal pressure over several days may be the optimal treatment. Pharmacological treatment with beta-blockers is safe, effective and the standard long-term treatment for the prevention of recurrence of variceal bleeding. The combination of beta-blockers with isosorbide-5-mononitrate needs further testing in randomized controlled trials. The use of haemodynamic targets for the reduction of the HVPG response needs further study, and surrogate markers of the pressure response need evaluation. Ligation has recently been compared with beta-blockers for primary prophylaxis, but there is as yet no good evidence to recommend banding for primary prophylaxis if beta-blockers can be given.

Role of angiotensin II in regulation of basal and sympathetically stimulated vascular tone in early and advanced cirrhosis

BACKGROUND & AIMS

The renin-angiotensin and sympathetic nervous systems are activated in cirrhosis. This study aimed to establish the role of angiotensin II (ANG II) in the regulation of basal and sympathetically stimulated vascular tone in preascitic cirrhotic patients and patients with diuretic-refractory ascites compared with age- and sex-matched healthy controls.

METHODS

Forearm blood flow (FBF) responses to lower body negative pressure (LBNP) and to subsystemic, intrabrachial infusions of losartan, an angiotensin II type 1 (AT(1)) receptor antagonist, norepinephrine, and ANG II were measured using venous occlusion plethysmography.

RESULTS

In all groups, ANG II and norepinephrine caused dose-dependent reductions in FBF (P < 0.001); responses to norepinephrine were similar across the 3 groups but those to ANG II were less in both cirrhotic groups than in controls (P < 0.01). Losartan caused a dose-dependent increase in FBF only in patients with refractory ascites (P < 0.01). LBNP caused less reduction in FBF in refractory ascites patients than in both preascitic patients and controls (P < 0.01).

CONCLUSIONS

Despite hyporesponsiveness to exogenous ANG II in both early and advanced cirrhosis, endogenous ANG II contributes to the maintenance of basal vascular tone only in advanced cirrhosis. These findings suggest a role of ANG II in the pathogenesis of ascites. Attenuated LBNP responses occurred only in advanced cirrhosis, without apparent interaction with endogenous ANG II.

Hepatorenal failure

Since the description of HRS more than 100 years ago, significant advances have been made in understanding the pathophysiology of HRS and in the management of these patients. There is now a therapeutic armamentarium: medical (ornipressin plus plasma volume expansion), radiographic (TIPS shunt), and surgical (liver transplantation). The diagnosis of HRS is no longer synonymous with a death sentence; instead, it is a therapeutic challenge, and a coordinated approach by intensivists, hepatologists, nephrologists, interventional radiologists, and transplant surgeons is needed to continue to improve the prognosis of cirrhotic patients presenting with HRS. Increased understanding of HRS will allow preventative rather than therapeutic measures to be used. As in all fields of medicine, these advances will come only with innovative clinical investigation.

Changes in glomerular filtration rate and renal plasma flow in cirrhotic rats during converting enzyme inhibition

During the development of cirrhosis ascites-edema, peripheral vasodilatation, hypotension and an increase of the plasma concentration of several neurohormones are frequently observed. Such complex changes in the hormonal profile hinders the assessment of the relative role of each in the pathophysiology of this disease. The purpose of this work was to evaluate in a rat model of experimental cirrhosis (phenobarbital/CCl4) the role of the renin-angiotensin system in the pre-ascitic stage of the disease using the converting enzyme inhibitor captopril. Cirrhotic rats showed diminished renal and hepatic perfusion. Compared to normal rats, glomerular filtration rate in cirrhotic rats was reduced from 0.75 +/- 0.11 to 0.42 +/- 0.06 mL/min/100 g BW, and renal plasma flow was reduced from 2.37 +/- 0.28 to 1.58 +/- 0.16 mL/min/100 g BW; the indocyanine green slope changed from -0.095 +/- 0.028 to -0.057 +/- 0.01; the plasma sodium concentration fell from 144 +/- 1.5 to 131 +/- 5.40 mEq/L (all < .05). The mean arterial pressure was not reduced in the cirrhotic rats. There was no ascites. Both the acute (25 mg i.v.) and chronic (25 mg i.p. daily plus 25 mg/L in drinking water) administration of captopril to cirrhotic rats induced an increase in glomerular filtration rate and renal plasma flow along with a steeper slope in indocyanine green decay (p < .05 for all three parameters) when compared to non-treated cirrhotic animals. No changes were observed in controls. In the balance studies, an increase in urinary volume along with a decrease in urinary osmolality was recorded in cirrhotic rats on chronic captopril treatment. In conclusion, our results show an activation of the renin-angiotensin system in these rats, as disclosed by the inhibition of the converting enzyme, as well as a possible interaction with ADH.

Ascites and renal functional abnormalities in cirrhosis. Pathogenesis and treatment

In the past few years, there have been important advances in the field of pathogenesis and management of ascites and hepatorenal syndrome in cirrhosis. A new pathogenic theory of ascites and renal dysfunction in cirrhosis has been presented and previously ill-defined conditions, such as refractory ascites and hepatorenal syndrome, have been defined precisely. The link between the diseased liver and the disturbances in renal function and vasoactive systems is not completely known, but a large body of evidence indicates that it consists of a circulatory dysfunction that affects mainly the arterial circulation and is characterized by an inability to maintain an effective arterial blood volume within normal limits. The research on the mechanisms of this circulatory dysfunction will give valuable information in the design of more pathophysiologically oriented therapeutic approaches to the management of ascites.

The hepatorenal syndrome

Hepatorenal syndrome may occur in any form of severe liver disease. It appears less common in children than adults, but still carries a poor prognosis. There are several factors involved in its aetiology, including a decreased renal perfusion pressure, activation of the renal sympathetic nervous system and increased synthesis of several vasoactive mediators, which may modulate glomerular filtration by acting as both renal vasoconstrictors and dynamic regulators of the glomerular capillary ultrafiltration coefficient, through their action on mesangial cells. This review will discuss the pathophysiology of the hepatorenal syndrome and some of the principles of management of patients with renal failure and severe liver disease. The role of renal support and liver transplantation will also be covered.

Haemodynamic effects of enalaprilat on portal hypertension in patients with HBsAg-positive cirrhosis

It has been suggested that enalaprilat inhibits the renin-angiotensin-aldosterone system in plasma and tissue; it may therefore reduce portal vascular pressure owing to secondary hyperaldosteronism in patients with liver cirrhosis. In order to evaluate this concept, 20 patients with hepatitis B surface antigen (HBsAg)-positive liver cirrhosis and portal hypertension received an intravenous infusion of 2.5 mg of enalaprilat. Wedged hepatic venous pressure, free hepatic venous pressure and cardiac index were measured before, immediately after, and then 15 min, 30 min and 1 h after intravenous enalaprilat infusion. The mean pressure gradient between wedged hepatic venous pressure and free hepatic venous pressure was significantly decreased, by 13% immediately after, 18% at 15 min, 23% at 30 min and 13% at 1 h after infusion of enalaprilat. Thirteen patients experienced a decrease of hepatic venous pressure gradient (HVPG) greater than 5 mmHg, another three 3-5 mmHg and the remaining four patients exhibited no significant change in HVPG. Systemic haemodynamic indices, including pulmonary arterial pressure, pulmonary capillary wedge pressure and central venous pressure, decreased significantly at 15 and 30 min after enalaprilat infusion (P < 0.01). Liver function, renal function and blood routine before and after enalaprilat infusion showed no significant change. There were no adverse effects during or after enalaprilat infusion. We conclude that enalaprilat infusion can quickly and safely reduce the hepatic venous pressure gradient in patients with HBsAg-positive cirrhosis.

Renal and hormonal responses to repeated treatment with enalapril in non-azotemic cirrhosis with ascites

Since a single dose of the angiotensin-converting enzyme inhibitor enalapril was shown to cause natriuresis in cirrhosis in a previous study, we investigated whether repeated doses of this substance would sustain a favorable renal effect in cirrhosis. Ten milligrams of enalapril maleate were administered once a day for 8 days to ten patients with non-azotemic cirrhosis and ascites. Enalapril reduced blood pressure significantly at 4 to 12 h (systolic blood pressure) and 2, 6, and 8 h (diastolic blood pressure) on day 2, compared to pretreatment (day 0) values, but this depressor effect decreased on day 8. No change in heart rate could be detected. Enalapril significantly suppressed serum angiotensin-converting enzyme activity and plasma aldosterone concentration (p < 0.001 to 0.01), which were elevated prior to treatment, with pretreatment values of 25.8 +/- 1.8 IU/l for serum angiotensin-converting enzyme activity and 241 +/- 67 pg/ml for plasma aldosterone concentration. This drug caused a 12 to 24% increase (p < 0.05 to 0.01) in mean daily urinary volume and a 40 to 54% increase (p < 0.001 to 0.01) in mean daily urinary sodium excretion from the respective pretreatment baselines during the 8-day period. Creatinine clearance was improved (p < 0.05) by the treatment, with mean improvement values from 24 to 34% above the pretreatment value of 47.4 +/- 4.3 ml/min.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacological treatment of portal hypertension: hemodynamic effects and prevention of bleeding

In the past 10 years, it has been clearly shown that vasoactive substances reduce portal pressure in patients or animals with portal hypertension. Some of these substances act by inducing splanchnic vasoconstriction, while others reduce hepatic and porto-systemic collateral vascular resistance and, thus, induce a portal hypotensive effect. Still others induce arterial hypotension, which causes a vasoconstrictive effect in the splanchnic territory. Since these drugs act on different vascular receptors, their combination should have a more marked effect on portal hypertension. Up to now, only nonselective beta-blockers have been used in the prevention of first gastrointestinal bleeding in patients with portal hypertension and esophageal varices and in the prevention of recurrent gastrointestinal bleeding. These trials have shown that propranolol or nadolol significantly reduce either a first episode of bleeding or recurrent bleeding. This pharmacological treatment also improves the survival rate in these patients. All of these studies have helped us to understand, in part, why gastrointestinal hemorrhage occurs in certain patients. Additional studies of beta-blockers or other substances are, nevertheless, necessary to select patients who will respond to this type of treatment. Finally, it is possible that the pharmacological treatment of portal hypertension may also be used before esophageal varices occur.

Effects of low-dose captopril on renal hemodynamics and function in patients with cirrhosis of the liver

BACKGROUND

In cirrhotic patients with ascites, captopril has deleterious effects on renal function, which have been referred to as captopril-induced arterial hypotension. The effects of this drug on renal function in cirrhosis were evaluated using low-dose captopril, thereby avoiding any change in arterial pressure.

METHODS

In a randomized, double-blind, placebo controlled, cross-over trial, the effects of 12.5 mg captopril on renal plasma flow, glomerular filtration rate (measured by radioisotopic techniques), and sodium excretion in healthy controls and cirrhotic patients with and without ascites were determined.

RESULTS

In healthy subjects, captopril only induced a significant, 18% increase in renal plasma flow. In contrast, glomerular filtration rate significantly decreased in patients with (from 108 +/- 7 to 78 +/- 9 mL/min) and without ascites (from 102 +/- 4 to 88 +/- 3 mL/min), whereas renal plasma flow did not change. Urinary sodium excretion also significantly decreased in ascitic patients (from 43.8 +/- 4.4 to 30.6 +/- 3.8 mumol/min).

CONCLUSIONS

These data suggest that angiotensin II contributes to maintain renal hemodynamics in cirrhosis with and without ascites.

Angiotensin-converting enzyme (ACE)-inhibition in cirrhosis. Pharmacokinetics and dynamics of the ACE-inhibitor cilazapril (Ro 31-2848)

The angiotensin-converting enzyme (ACE)-inhibitor, cilazapril, is converted to its active metabolite, cilazaprilat, by ester hydrolysis in the liver. The pharmacokinetics and pharmacodynamics of a single 1 mg oral dose of cilazapril were investigated in 10 healthy volunteers and in 9 cirrhotic patients with compensated cirrhosis and portal hypertension. A significantly increased mean plasma peak concentration (40.0 +/- 13.6 ng/ml vs. 25.5 +/- 7.9 ng/ml; p < 0.05) and a decreased apparent oral clearance (7.8 +/- 6.0 l/h vs. 16.4 +/- 5.4 l/h; p < 0.05) of cilazapril were found in cirrhotic patients compared to healthy volunteers. The plasma concentration of cilazaprilat declined in 2 phases. In both phases the plasma half-life was significantly longer in patients with cirrhosis (1st phase: 2.5 +/- 0.8 h vs. 1.7 +/- 0.6 h; p < 0.05; 2nd phase: 46.2 +/- 16.6 h vs. 28.8 +/- 4.7 h; p < 0.001). Consequently, cilazaprilat concentrations at 24 h were higher in patients than in volunteers (1.42 +/- 0.33 ng/ml vs. 0.87 +/- 0.14 ng/ml; p < 0.001). The predose activity of the ACE (26.3 +/- 7.3 U/l vs. 16.8 +/- 4.5 U/l; p < 0.005) and plasma renin activity (3.3 +/- 3.2 ng/ml/h vs. 1.4 +/- 1.0 ng/ml/h) were higher in patients than in volunteers. Maximum ACE-inhibition occurred at similar times in patients (2.7 h) and volunteers (2.3 h). Maximum ACE-inhibition was slightly higher in volunteers (94.6%) than in patients (90.6%). At later time points (> 24 h), however, ACE-inhibition was more pronounced in patients (at 72 h: 39.6 +/- 6.9% vs. 23.5 +/- 8.2%; p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Portal pressure, renal function and hormonal profile after acute and chronic captopril treatment in cirrhosis

The acute effects of captopril in cirrhosis are well known but there are few descriptions of the pattern of response to chronic administration of captopril in this disease. Nine nonuraemic cirrhotic patients with ascites and portal hypertension were studied after 1 week on fixed sodium and water intake (balance diet) and following acute and chronic treatment with captopril (three doses of 25 mg every 30 min and 75 mg.day-1 for three weeks, respectively). Whilst on the balance diet, 7/9 patients were unable to excrete the amount of sodium ingested. After the acute administration of captopril, a significant reduction was seen in arterial blood pressure (86.9 vs 77 mm Hg), with no change in the intra-hepatic pressures (free suprahepatic pressure, FSHP: 15.0 vs 12.1 mm Hg and wedged suprahepatic pressure, WSHP: 22.9 vs 20.7 mm Hg). After chronic captopril treatment, a drop was observed in portal pressure (FSHP: 9.4 mm Hg and WSHP 18.8 mm Hg, NS) and the arterial pressure returned to its basal level. The plasma aldosterone concentration decreased, whilst noradrenaline and dopamine increased significantly, the latter more than the former, leading to a reduction in the noradrenaline/dopamine ratio (14.5 vs 5.0). Seven out of nine patients showed enhanced natriuresis and the remaining two, who previously had had a positive sodium balance failed to do so. These haemodynamic, hormonal and renal changes were interpreted as evidence of blockade of angiotensin II generation by captopril, and also as a homoeostatic response by the sympathetic nervous system.