EFFECTS OF VENA-CAVAL BANDING IN EXPERIMENTALLY-INDUCED MULTIPLE PORTOSYSTEMIC SHUNTS IN DOGS

Effects of vena caval banding on portal venous and vena caval hemodyna mics were examined in 6 control dogs and in 10 dogs that had undergone attenuation (banding) of the abdominal part of the caudal vena cava a nd had dimethylnitrosamine-induced multiple portosystemic shunts (PSS) . Additionally, indocyanine green (ICG) extraction and clearance after infusion to steady state were used to calculate hepatic plasma flow i n these dogs. Sixteen dogs were randomly assigned to 2 groups: control (n = 6) or diseased(n = 10). Diseased dogs were administered dimethyl nitrosamine (2 mg/kg, PO, twice weekly) until multiple Pss developed, as assessed by results of clinical laboratory tests, ultrasonography, and hepatic scintigraphy. Shunts were confirmed visually at celiotomy and by contrast portography. Venous pressures (caudal vena caval, port al, and hepatic) were recorded before and after vena caval banding for up to 7 days in dogs from both groups. Peritoneal cavity pressures we re recorded in all dogs after closure of the body wall. To determine I CG extraction and clearance, a bolus injection of ICG (0.5 mg/kg, IV) was administered, followed by steady-state infusion of 0.097 mg/min. E xtractions and clearances of ICG were measured, and from these, hepati c plasma flow rates were determined immediately before and after bandi ng and at 6 hours, 48 hours, and 7 days after banding. The gradient (c audal vena caval pressure within 1 to 2 mm of Hg of portal pressure) b etween caudal vena cava and portal venous pressures established at ban ding was maintained after the first hour in both groups. Caudal vena c ava pressures established at banding were maintained throughout the st udy, with the exception of the first hour in diseased dogs. Extraction ratios were higher in control dogs at all times, except at 48 hours. Clearance was higher in control dogs at all times. Hepatic plasma flow did not differ between groups, except immediately after banding, when flow was greater in diseased dogs, and differences were not found ove r time in either group. This study indicated that vena caval banding i n this model of experimentally induced multiple PSS increases and main tains caudal vena cava pressure, relative to portal venous pressure (a fter the first hour) for 7 days, and that calculated hepatic plasma fl ow is not persistently improved by vena caval banding.