Effects of vasopressin on portal hemodynamics in patients with portal hypertension.

In view of the variability in the magnitude of the response of portal venous pressure to vasopressin in man, we investigated the effect of vasopressin on portal hemodynamics in seven patients with portal hypertension by simultaneous catheterization of the portal and the hepatic vein and the measurement of portal venous flow by an echo-Doppler flowmetry. Infusion of vasopressin (0.3 U/min) significantly decreased portal venous pressure (-36%), the gradient between portal venous pressure and free hepatic venous pressure (-50.6%), and portal venous flow (-54.3%) but did not reduce mean arterial pressure and pulse rate. Thus, vasopressin seems to decrease portal venous pressure by reducing portal venous flow.