Beta-receptor blocking treatment in portal hypertension

A study of the antiulcer mechanisms of propranolol in rats

Although propranolol has been shown to protect against ethanol and stress ulceration, the antiulcer mechanisms are still unclear. The present study examined the antiulcer mechanisms of propranolol in three different types of ulceration induced respectively by ethanol (60%), indomethacin (30 mg/kg) and stress (cold-restraint). Propranolol pretreatment in the highest dose (10 mg/kg) given either intraperitoneally (i.p.) or orally (p.o.) prevented gastric mucosal damage in these three ulcer models. The three doses of the drug (2.5, 5 or 10 mg/kg) dose-dependently decreased systemic blood pressure which was accompanied by a reduction of gastric mucosal blood flow. These findings suggest that the protection was unrelated to an improvement of local circulation in the stomach. However, propranolol preserved the mucus levels in the three types of ulcer models. The beta-adrenoceptor blocker also increased the basal gastric mucosal potential difference. These findings indicate that propranolol strengthens the mucosal barrier by the preservation of mucosal mucus and enhancement of the mucosal integrity in the stomach.

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.

Pathophysiology and clinical basis of prevention and treatment of complications of chronic liver disease

Chronic liver failure is characterized by the appearance of jaundice, ascites, encephalopathy and/or gastrointestinal bleeding. Acute episodes of hepatic decompensation are frequently precipitated by additional events, e.g. septicaemia, diuretic therapy or excessive protein intake. Identification, correction and treatment of these precipitating factors are first steps in the management of chronic liver failure. Nutritional support is important in the treatment of cirrhotic patients, because malnutrition is one of the major determinants of patient outcome. Management of encephalopathy reduces the appearance of gut-derived nitrogenous toxins and corrects imbalances in amino acid metabolism. Treatment of ascites is salt restriction supported by gentle and incremental administration of diuretics. Ursodesoxycholic acid has become a new and promising modality in the management of cholestatic liver diseases. If conservative therapy fails to recompensate liver function, liver transplantation may be indicated.