[Vasoconstrictive Therapies for Bleeding Esophageal Varices and their Mechanisms of Action]

Abstract

Variceal bleeding is one of the most dramatic complications in gastroenterology and has a high mortality rate. Early treatment with vasoactive drugs can save lives when skilled endoscopists are not immediately available. Vasoactive drugs like terlipressin, somatostatin or octreotide are not only indicated as first-choice emergency treatment, but they also increase the success rate of endoscopic treatments. Whereas the efficacy and mechanisms of action of terlipressin to arrest haemorrhage and to improve the disturbed cardiovascular situation of cirrhotic patients, including those with hepatorenal syndrome, are well documented, the efficacy and mechanisms of action of somatostatin and octreotide remain unclear and uncertain. On account of its vasoconstrictive effects on the dilated splanchnic blood vessels, terlipressin reduces blood flow into the portal vein and, thus, reduces portal venous pressure and blood flow through porto-systemic shunts. As a consequence, variceal bleeding is arrested, central and arterial hypovolaemia is corrected, and activation of the renin-angiotensin-aldosterone system as well as the sympathetic nervous system is reduced, leading to lower intrahepatic and intrarenal resistance. The result is an improvement of organ perfusion - including perfusion of the kidneys and the liver - as well as an improvement of the hyperdynamic cardiovascular situation and a better survival rate. Whereas terlipressin has been shown to stimulate kidney function and to prolong survival time in patients with bleeding esophageal varices as well as those with hepatorenal syndrome, no such promising effects were observed with somatostatin or octreotide.