Active and passive liver microvascular responses from angiotensin, endothelin, norepinephrine, and vasopressin

Vasoconstrictor agents may induce a decrease in hepatic vascular volume passively, by decreasing distending pressure, or actively, by stimulating contractile elements of capacitance vessels. Hepatic venular resistance was estimated in anesthetized rabbits from hepatic venular pressure (Pμhv; by servo-null micropipette), inferior vena cava pressure, and total hepatic blood flow (Fhv; by ultrasound flow probe). Changes in liver volume were estimated from measures of liver lobe thickness. Angiotensin (ANG) II, endothelin (ET)-1, norepinephrine (NE), and vasopressin (VP) were infused into the portal vein at a constant rate for 5 min. We conclude that ANG II and NE induced active constriction of hepatic capacitance vessels, because the liver lobe thickness decreased significantly even though Pμhv and portal venous distending pressure (Ppv) increased. All four agents increased splanchnic and hepatic venous resistances in similar proportions. With VP, Pμhv and Ppv decreased, but with ET-1, Pμhv and Ppv increased. However, lobe thickness was not significantly changed by either drug during the infusion compared with the 2-min control period. Thus VP and ET-1 have only minor effects on hepatic capacitance vessels. ET-1, at 0.04 μg · min−1 · kg body wt−1, caused an increase in systemic arterial blood pressure, but erythrocyte movement through the sinusoids in some animals stopped.

Portacaval Shunt for Portal Hypertensive Gastropathy

Portal hypertensive gastropathy is a vascular disorder of the gastric mucosa distinguished by ectasia of the mucosal capillaries and submucosal veins without inflammation. During 1988 to 1993, 12 patients with biopsyproven cirrhosis (10 alcoholic, 2 posthepatitic) were evaluated and treated prospectively by portacaval shunt for active bleeding from severe portal hypertensive gastropathy. Eleven patients had been hospitalized for bleeding three to nine times previously, and one was bleeding uncontrollably for the first time. Requirement for blood transfusions ranged from 11 to 39 units cumulatively, of which 8 to 30 units were required specifically to replace blood lost from portal hypertensive gastropathy. Admission findings were ascites in 9 patients, jaundice in 8, severe muscle wasting in 10, hyperdynamic state in 9. Child's risk class was C in 7, B in 4, A in 1. Ten of the 12 patients had previously received repetitive endoscopic sclerotherapy for esophageal varices, which has been reported to precipitate portal hypertensive gastropathy. Eight patients had failed propranolol therapy for bleeding. Portacaval shunt was performed emergently in 11 patients and electively in 1, and permanently stopped bleeding in all by reducing the mean portal vein-inferior vena cava pressure gradient from 251 to 16 mm saline. There were no operative deaths, and two unrelated late deaths after 13 and 24 months. During 1 to 6.75 years of followup, all shunts remained patent by ultrasonography, the gastric mucosa reverted to normal On serial endoscopy, and there was no gastrointestinal bleeding. Recurrent portal-systemic encephalopathy developed in only 8% of patients. Quality of life was generally good. It is concluded that portacaval shunt provides definitive treatment of bleeding portal hypertensive gastropathy by eliminating the underlying cause, and makes possible prolonged survival with an acceptable quality of life.