Comparative haemodynamic effects of betaxolol and propranolol in patients with cirrhosis

Hemodynamic Response to Carvedilol is Maintained for Long Periods and Leads to Better Clinical Outcome in Cirrhosis: A Prospective Study

BACKGROUND

Non-selective beta-blockers (NSBBs), e.g. propranolol, are recommended for prophylaxis of variceal bleeding in cirrhosis. Carvedilol, a newer NSBB with additional anti-α1-adrenergic activity, is superior to propranolol in reducing portal pressure. Repeated HVPG measurements are required to identify responders to NSBB. We aimed to determine whether a single-time HVPG measurement, using acute-hemodynamic-response-testing, is sufficient to predict long-term response to carvedilol, and whether these responders have better clinical outcome.

METHODS

Consecutive patients with cirrhosis, aged 18-70 years, in whom NSBB was indicated for primary/secondary prophylaxis of variceal bleeding, and who underwent HVPG were included. Acute-hemodynamic-response was defined as a decrease in HVPG ≥10% from baseline or absolute HVPG value declining to <12 mm Hg, 1 h after 25 mg oral carvedilol. The aims of the study were to determine: the proportion of patients who achieved acute-hemodynamic-response to carvedilol; whether HVPG-response is maintained for 6 months; and clinical outcome of acute-responders to carvedilol therapy for 6 months.

RESULTS

The study included 69 patients (median age 51, males 93%). Alcohol was the most common etiology; 59% patients belonged to Child-Pugh class B. NSBB was indicated for primary prophylaxis in 36% and secondary prophylaxis in 64% patients. According to the response criteria, 67% patients were found to be acute-hemodynamic-responders. At 6 months, 92% patients were found to be still maintaining their hemodynamic response to carvedilol. Using intention-to-treat analysis, 76% patients maintained their response. These acute responders, on chronic treatment with carvedilol during the 6-month period, had lesser episodes of variceal bleeding, better ascites control, and improved MELD and CTP scores, than non-carvedilol treated non-responders. However, survival remained similar in both the groups.

CONCLUSIONS

A single-time HVPG measurement with acute-hemodynamic-response-testing is simple and reliable method for identifying patients who are more likely to respond to carvedilol therapy. The HVPG-response is maintained over a long period in majority of these patients and carvedilol therapy leads to better clinical outcome in these patients.

Review article: a drug therapy for the prevention of variceal haemorrhage

The development of varices is a major complication of cirrhosis, and variceal haemorrhage has a high mortality. There have been major advances in the primary and secondary prevention of variceal haemorrhage over the last 20 years involving endoscopic, radiological and pharmacological approaches. This review concentrates principally on drug therapy, particularly on the numerous haemodynamic studies. Many of these drugs have not been studied in clinical trials, but provide data about the underlying pathogenesis of portal hypertension. Also covered in this review are the randomized controlled trials and meta-analyses that involve a large number of patients. These trials involve relatively few drugs such as non-selective beta-blockers and nitrates. Correlations between haemodynamic and clinical parameters are discussed. Despite the recent increase in the use of alternative endoscopic therapies, an effective and well tolerated drug remains a clinically important research goal.

Altered thyroid status modulates portal pressure in normal rats

BACKGROUND & AIMS

Disturbances in thyroid function in humans and experimental animal models have been associated with alterations in liver function and portal circulation. We have previously shown that hypothyroidism can significantly reduce portal pressure in portal vein ligated rats as well as inhibit the development of cirrhosis and fulminant hepatic failure following toxic liver injury. The aim of this study was to determine the effects of increased and decreased thyroid function on portal pressure in rats with normal liver histology and portal circulation.

METHODS

Three groups of 12 Wistar rats each were studied over a 30 day period: euthyroid (Group 1), hyperthyroid (Group 2) and hypothyroid (Group 3). Hyperthyroidism was induced by subcutaneous injection of triiodothyronine (400 microg/100g body weight) every ten days during the study period. Hypothyroidism was induced by methimazole (0.04% in drinking water) from 2 weeks prior to and throughout the 30 day study. Serum triiodothyronine (T3) and thyroid stimulating hormone (TSH) levels were determined to confirm the induction of hyper- and hypothyroidism. Portal pressure was assessed by direct catheterization of the portal vein prior to sacrifice. Indirect confirmation of changes in portal circulation was obtained by determining splenic weight at the time of sacrificing the animals. Animals were sacrificed at 10 day intervals throughout the 30 day study.

RESULTS

Triiodothyronine treated rats were hyperthyroid compared to controls, with an elevation in serum T3 levels (3.8+/-0.9 mmol/L vs 1.3+/-0.4 mmol/L, p<0.05). In rats treated with methimazole, hypothyroidism was confirmed by a 7-fold increase in serum TSH compared to controls (1.8+/-0.4 vs 0.24+/-0.04 mmol/L, p<0.01). Portal pressure was significantly higher in the triiodothyronine treated rats compared to controls (12.8+/-1.7 and 9.6+/-0.75 cm H2O, p<0.001). Splenic weights in hyperthyroid rats were significantly higher than in controls (579+/-44 vs 478+/-46 mg, p<0.01). Portal pressure was significantly lower in the methimazole treated group compared to the control group (8.13+/-0.68 vs 9.6+/-0.75 cm H2O, p<0.01) as were splenic weights (400+/-33 vs 478+/-46 mg, p<0.01).

CONCLUSION

These studies demonstrate that disturbed thyroid function exerts significant hemodynamic effects on the portal circulation in normal rats and complements results from previous similar studies in cirrhotic animals.

Inhibition of concanavalin A-induced acute T cell dependent hepatic damage in mice by hypothyroidism

AIMS/BACKGROUND

Concanavalin A (Con A) activates T lymphocytes and causes acute T-cell-mediated hepatic injury in mice. Decreased thyroid hormonal production is associated with a variety of immunological manifestations, including inactivation of macrophages with reduced TNF production and reduced soluble IL-2 receptors in the serum. We have recently shown that hypothyroidism prevents the development of cirrhosis and also minimizes hepatic damage in rats with fulminant hepatic failure. In the present study we examined the effects of hypothyroidism on a mouse model of Con A induced T cell-mediated acute hepatitis.

METHODS

Hypothyroidism was induced both medically (MMI, PTU) and surgically. Eight groups of 10 mice each were studied: euthyroid controls (2 groups: water, Con A) and hypothyroid (6 groups: MMI, PTU, Surgical, MMI-Con A, PTU-Con A, Surgical-Con A).

RESULTS

Hepatic inflammation was significantly decreased in each of the Con A treated hypothyroid groups of mice. The serum transaminases, TNF-alpha and IL-6 levels were significantly elevated in the Con A treated group while near normal levels were found in the hypothyroid Con A treated groups (mean+/-SE AST: 1499+/-18 vs 78+/-10 IU/l, p<0.001; TNF: 2500+/-250 vs 135+/-15 pg/ml, p<0.001, IL-6: 12,200+/-300 vs 1260+/-140 pg/ml, p<0.001, respectively).

CONCLUSIONS

Hypothyroidism, independent of the mode of induction, can effectively inhibit the development of acute T cell-mediated liver damage in mice. These results suggest that some decrease in thyroid function might have a role in the prevention of immune mediated liver diseases.

Liver function in cirrhotic patients in the euthyroid versus the hypothyroid state

We recently showed that some decrease in thyroid hormone blood levels can effectively and significantly prevent the development of cirrhosis and fulminant hepatic failure and decrease portal pressure in three different rat models. This study was conducted to determine whether hypothyroidism has a beneficial effect over euthyroidism on patients with active liver cirrhosis of different etiologies. The medical files of hypothyroid patients with cirrhosis who were referred to the Tel-Aviv Medical Center between the years 1980 and 1995 were retrospectively evaluated. Of 3,528 patients with biopsy-proven cirrhosis and 4,738 hypothyroid patients who were identified, only 46 (25 female, 54%; mean age, 52.3 +/- 9.1) met the eligibility criteria. The patients suffered from cirrhosis (mean, 9.5 +/- 4.3 years; range, 4-23) and had hypothyroidism (mean, 12 +/- 6 years; range, 4-31). Most patients suffered from hypothyroidism of unknown etiology (85%), whereas the rest had hypothyroidism after surgical/iodine ablation of the gland. In the hypothyroid versus the euthyroid state, a significant negative correlation was found between thyroid-stimulating hormone blood levels and both functional and synthetic liver function tests (p < 0.001). A significant negative correlation was also found between thyroid-stimulating hormone blood levels and clinical deterioration manifested as bleeding varices, the development of ascites, and episodes of encephalopathy. We conclude that in patients with liver cirrhosis, the liver function in the hypothyroid state tend to be better than in the euthyroid state. A mild controlled decreased thyroid function may be beneficial for euthyroid cirrhotic patients.

Prophylactic treatment of patients with esophageal varices: is it ever indicated?

The prognosis of patients who bleed from esophageal varices is dismal. Prophylactic treatment of the varix or the elevated portal venous pressure offers a possibility of improving the outlook for these patients. However, as only approximately one-third of patients with varices bleed during their lifetime, correct identification of high-risk patients is vital before embarking on prophylaxis. At present, neither European or Japanese selection criteria are perfect in this respect. The documented incidence of initial variceal bleeding varies between 27% and 48%, and most bleeding episodes occur within the first year after varices are diagnosed. Data from six randomized controlled trials comparing prophylactic beta-blockers with placebo demonstrated a decreased incidence of bleeding in propranolol-treated patients, which in large measure may depend on patient compliance and did not significantly affect survival in all but one study. Early randomized studies of prophylactic sclerotherapy have shown significant reductions in both the incidence of bleeding and mortality, but this promise has not been sustained by subsequent trials, and indeed sclerotherapy was detrimental in two studies. The impressive results in highly selected patients treated in Japan by prophylactic surgery are unlikely to be repeated in a Western setting, involving patient populations that consist predominantly of alcoholic cirrhotics. At present prophylaxis with beta-blockade seems to offer the best therapeutic option, but the future may lie in the development of new interventional techniques such as transjugular intrahepatic portosystemic stent shunting (TIPS) or variceal banding, and ultimately with hepatic transplantation.

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.

Review article: the pathophysiology and pharmacological treatment of portal hypertension

The pathogenesis of portal hypertension remains poorly understood. Similarly, pharmacological manipulation for the prevention and treatment of variceal haemorrhage has not fulfilled the promise of the 1980s. This article reviews current concepts in the pathophysiology of portal hypertension and considers pharmacotherapy for the treatment of variceal bleeding.

Long term management of oesophageal varices

Effective control of variceal rebleeding (secondary prophylaxis) or prevention of the initial bleeding (primary prophylaxis) are the main objectives of the treatment of portal hypertension. Endoscopic sclerotherapy is the treatment of choice for secondary prophylaxis, since it significantly decreases rebleeding and, to some extent, mortality. A combination of propranolol and sclerotherapy may be of benefit by decreasing postsclerotherapy rebleeding. Endoscopic variceal band ligation and transjugular intrahepatic shunt are emerging as useful alternative techniques. Devascularisation and preferably selective shunts should be reserved for use as salvage of sclerotherapy failures. Liver transplantation, if feasible, could become the ultimate therapy by controlling variceal bleeding and improving hepatic function. Pharmacotherapy, while not very successful for secondary prophylaxis, has shown promise for primary prophylaxis of variceal bleeding. Nonselective beta-blockers significantly decrease the rebleeding rates but are associated with only marginal survival benefits. beta-Blockers alone cannot decrease the hepatic venous pressure gradient adequately (to less than 12mm Hg). Combination with nitrates and other drugs may prove beneficial and requires clinical evaluation. Endoscopic sclerotherapy and surgery have little role in primary prevention of variceal bleeding in patients with cirrhosis but need evaluation in noncirrhotic patients.

Divergent circulatory effects of betaxolol in conscious and anesthetized normal and portal hypertensive rats

We aimed to define the circulatory effects of beta 1-blockade in conscious normal and portal hypertensive rats and determine if pentobarbital anesthesia affected these responses. A selective beta 1-antagonist, betaxolol, was given to four groups: conscious and anesthetized sham-operated and portal hypertensive rats. Cardiac output and splanchnic organ blood flows were measured by radioactive microspheres twice in each rat, before and 15 min after betaxolol. Both groups of conscious rats maintained mean arterial pressure despite significant decreases in cardiac output and heart rate, by increasing total peripheral resistance. Anesthetized rats were unable to do this and thus also diminished arterial pressure significantly, with portal hypertensive rats showing greater decreases than sham-operated rats. Portal tributary flow and portal pressure decreased only in the anesthetized rats. Autoregulation of splanchnic blood flow was not uniform between groups or organs: although splenic flow decreased in all four groups, intestinal blood flow decreased only in anesthetized portal hypertensive rats. The greatest decreases in several splanchnic organ blood flows were seen in this latter group. These results indicate that: (i) pentobarbital markedly changes systemic and splanchnic responses to beta 1-blockade; (ii) splanchnic autoregulation is not uniform--the intestinal circulation enjoys more protection than the splenic; and (iii) portal hypertensive rats seem to be more vulnerable to the circulatory effects of beta 1-blockade.

Current status and future goals of the pharmacologic reduction of portal hypertension

The continuous oral administration of different drugs can produce a sustained reduction in portal pressure in patients with portal hypertension. beta-Adrenergic antagonists, alpha 2-adrenergic agonists, and 5-hydroxytryptamine-receptor antagonists have been evaluated for their long-term effects on portal pressure reduction. Clinical studies show that gastrointestinal bleeding can be prevented by pharmacologic therapy. This type of treatment is efficient and safe, and, if a drug has no clinical effect, a different drug or a combination can be used. Several problems, however, need to be addressed, including patient compliance, selection of responders, and hemodynamic evaluation of the treatment and its duration. Although pharmacologic treatment of portal hypertension is known to be efficient, there are advances still to be made.

Long-term pharmacologic therapy of portal hypertension

Beta-blockers modify splanchnic hemodynamics in cirrhotic patients. Nonselective beta-blockers are more effective than selective beta-blockers. Azygos blood flow, as a measure of collateral circulation, including that through varices, is always reduced, but the effects on portal pressure, whether measured directly or by the wedged hepatic venous pressure, are variable. The initial reported correlation between a 25% reduction of resting pulse rate and similar percentage reduction in the wedged free hepatic venous gradient has not been reproduced in subsequent studies. Therefore, to study the effect of changes in hemodynamic indices and the likelihood of variceal bleeding, direct measurements of such indices need to be made in clinical trials. At present, only one primary-prevention trial of propranolol suggests that a hemodynamic index can be used to identify patients given propranolol who will not bleed. Some clinical factors may be important in identifying nonresponders in trials of secondary prevention, but these are not universally recognized. The results of secondary-prevention studies are very heterogeneous, and it is difficult to understand why this is so. However, comparative studies versus sclerotherapy suggest that reductions in rebleeding and mortality are similar. Pharmacologic treatment, including beta-blockade, is ideal for primary prevention of variceal bleeding. The initial results from randomized studies are more homogeneous regarding the benefit of beta-blockers than in the secondary-prevention studies, although there is still doubt about the response in cirrhotics with ascites. No fatal complications due to propranolol administration have been reported in cirrhotic patients, and the complications are reversible. The future of pharmacologic therapy for portal hypertension lies in combination therapy. The addition of vasodilators to beta-blockers appears to potentiate their effect on portal pressure reduction. The results of clinical trials are awaited with great interest.

Hyperkinetic circulatory syndrome in patients with presinusoidal portal hypertension. Effect of propranolol

This study evaluates systemic and splanchnic haemodynamics and the effect of propranolol in 15 patients with presinusoidal portal hypertension (portal vein obstruction, n = 11; schistosomiasis, n = 4). These patients exhibited a hyperkinetic circulatory syndrome characterized by high cardiac index (4.4 +/- 1.61.min-1.m-2, mean +/- S.D.) and by low systemic vascular resistance despite normal liver function and sinusoidal pressure. Hepatic blood flow was decreased in half of the patients with portal vein obstruction. Azygos blood flow, an estimate of superior portal-systemic collateral circulation, was markedly increased in all patients (0.46 +/- 0.19 l/min, upper limit of normal: 0.19 l/min). Therefore, in these patients with normal hepatic venous pressure gradient, azygos blood flow measurement provides an index of splanchnic haemodynamic changes. Propranolol administration (15 mg, i.v.) reduced the hyperkinetic circulatory syndrome, with a significant decrease in heart rate (-17 +/- 6%), cardiac index (-25 +/- 12%) and azygos blood flow (-40 +/- 26%) and a significant increase in systemic vascular resistance (+40 +/- 40%). These results suggest that the hyperkinetic circulatory syndrome observed in these patients, could be related to an increase in beta-adrenergic activity. The decrease in azygos blood flow, after propranolol administration, was significantly correlated (r = 0.94) with the increase in right atrial pressure. This finding suggests that propranolol may act through an increase in portal-systemic collateral venous tone. These haemodynamic results justify, in patients with presinusoidal portal hypertension, clinical trials investigating the beneficial effect of beta-blockers on gastrointestinal bleeding caused by portal hypertension.