Preventing a first variceal bleed with non-selective beta-blockers
Non-selective beta-blockers (acting on both the heart and the gut vessels) lower pressure in the portal vein and cut the risk of a first bleed from dilated oesophageal veins.
Remember
To prevent a first bleed from medium or large oesophageal varices (dilated veins in the lower oesophagus), use a non-selective beta-blocker such as carvedilol or propranolol; banding with rubber bands is the alternative if a beta-blocker cannot be taken or is not tolerated.
Oesophageal varices are dilated veins in the lower oesophagus. They form when the pressure in the portal vein rises, usually because of cirrhosis. Blood then finds a way round the scarred liver through collateral veins (natural bypass channels), and in the oesophagus these are thin-walled and fragile.
Varices cause no symptoms, which is why they are looked for at endoscopy in people with cirrhosis. They can bleed suddenly and severely. The wall tension in these veins rises with the pressure inside them, so rupture becomes more likely as the pressure climbs. Drug treatment before any bleed therefore aims to lower the portal pressure. This is primary prevention, meaning treatment before a first bleed.
Non-selective beta-blockers such as propranolol or carvedilol lower that pressure in two ways. By blocking beta-1 receptors in the heart, they lower heart rate and cardiac output, so less blood is pumped into the splanchnic circulation (the circulation of the gut). By blocking beta-2 receptors in the gut arteries (stimulating these receptors widens the arteries), they leave the alpha-1 vasoconstricting effect unopposed, so the arteries narrow and less blood flows into the portal vein. With less inflow, portal pressure falls and the varices are under less tension.
Bisoprolol, a selective beta-1 blocker, slows the heart yet leaves the gut arteries alone, so it is not used for this purpose. For medium or large varices, NICE says to offer carvedilol or propranolol; if a beta-blocker cannot be taken or is not tolerated, endoscopic variceal band ligation (rubber bands placed around the varices) is the alternative.
Key facts
- Aim of drug treatment
- to lower the pressure in the portal vein, because the tension in the thin-walled varices rises with that pressure
- Drugs
- non-selective beta-blockers such as propranolol or carvedilol
- Heart effect
- blocking beta-1 receptors lowers heart rate and cardiac output
- Gut effect
- blocking beta-2 receptors in the gut arteries (stimulating these receptors widens the arteries) leaves alpha-1 vasoconstriction unopposed, so less blood enters the portal vein
- Alternative
- for medium or large varices, endoscopic variceal band ligation if a beta-blocker cannot be taken or is not tolerated
- Primary prevention
- treatment before a first bleed
Exam traps
- A proton pump inhibitor (a drug that reduces gastric acid secretion) does not lower the risk of a variceal bleed, since varices bleed under high pressure in their thin walls, not because of acid.
- A selective beta-1 blocker (such as bisoprolol) lowers heart rate but leaves the gut arteries alone, so portal pressure hardly changes and it is not used to prevent a first variceal bleed.
- A TIPS, a shunt that diverts portal blood through the liver into the hepatic vein, is kept for bleeding that cannot be controlled or keeps coming back, and is too invasive for someone who has not bled.
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