Intravenous versus superior mesenteric artery vasopressin infusions for the treatment of variceal bleeding.

The effects of 30-minute intravenous and superior mesenteric artery (SMA) infusions of vasopressin in dosages of 2.75 mU and 14 mU per min per kg were compared in five dogs that had cirrhosis and portal hypertension induced by fractionated intraportal polyvinyl alcohol injections. A reduction in portal pressure of approximately 35% was found with both SMA doses and the larger intravenous vasopressin dose, while the smaller intravenous dose reduced portal pressure only 18%. A significantly larger decrease in portal blood flow was found with SMA than intravenous vasopressin administration. Cardiovascular side effects were dose-dependent but independent of the administration mode. Liver enzymes were not affected. Portal vein thrombosis occurred in one dog after the larger SMA dose.