How I do it Outflow modulation to target liver regeneration: Something old, something new *

Background: Stimulation of hepatic hypertrophy is a useful aid to accomplish hepatic resections when the future liver remnant (FLR) is small. Although inflow occlusion, especially through portal flow, has been extensively studied, the role of outflow modulation has not yet been described. Methods: Description of outflow modulation to tailor hypertrophy of future liver remnant in the context of bilobar metastatic disease. A patient with small FLR (segments I and IV) was managed with a two-stage procedure. The first stage consisted of a right hepatectomy and modulation of the left hepatic vein outflow through reduction of its diameter, with macroscopic congestion of segments IIeIII. The second stage consisted of a left lateral sectionectomy six weeks later. Postoperative courses were uneventful without any sign of liver failure. Results: Following the first stage procedure computed tomography revealed distinct hypertrophy rates between sections. The non-congested area had an increase of 156% in the volume of segment IV (from 137 to 351 cm 3 ) and 100% in the volume of segment I (from 20 to 40 cm 3 ). The congested area, segments IIeIII, increased only 24% (from 205 to 253 cm 3 ).