Résumé
The hemodynamical effect of the collateral portosystemic circulation upon the portal system has not yet been fully understood. The US-Doppler made possible the non-invasive study of the portal system by evaluating the parameters: flow direction, diameter and flow velocity in it's vessels. AIMS: To study the paraumbilical vein as a collateral portosystemic pathway and identify patterns for appraising its hemodynamic importance to the portal system. METHOD: US-Doppler study of the portal system of 24 patients with Mansoni's hepatosplenic schistosomic portal hypertension, previous esophagic variceal bleeding and patent paraumbilical vein with hepatofugal flow. The diameter and the mean flow velocity were measured in the paraumbilical vein and so were the mean flow velocity in the portal vein, right and left portal branches. The Pearson test (linear correlation) was applied to the portal vein's mean flow velocity and the paraumbilical vein's diameter and mean flow velocity. The patients were divided in four groups: D1-paraumbilical vein with diameter < 0.68 cm (n = 14), D2-paraumbilical vein with diameter > or = 0.68 cm (n = 10), V1-paraumbilical vein with mean flow velocity < 18.41 cm/seg (n = 13) and V2-paraumbilical vein with mean flow velocity > or = 18.41 cm/seg (n = 11). The mean flow velocity in the portal vein, right and left portal branches of the four groups were compared. RESULTS: The paraumbilical vein diameter was 0.68 +/- 0.33 cm (range: 0.15-1.30 cm) and the mean flow velocity was 18.41 +/- 11.51 cm/seg (range: 5.73-38.20 cm/seg). The linear correlation between the portal vein's mean flow velocity/paraumbilical vein diameter and the paraumbilical vein's mean flow velocity showed r = 0.504 and r = 0.735, respectively. In the group D2 there was an increase in the mean flow velocity in the portal vein (17.80 +/- 3.42/22.30 +/- 7.67 cm/seg) and in the left portal branch (16.00 +/- 4.73/22.40 +/- 7.90 cm/seg). In the group V2 there was an increase in the mean flow velocity in the portal vein (16.31 +/- 3.49/21.96 +/- 5.89 cm/seg) and in the left portal branch (14.22 +/- 4.41/21.94 +/- 7.20 cm/seg). There was no change in the right portal branch (13.67 +/- 5.74/15.43 +/- 3.43 cm/seg). CONCLUSIONS: In portal hypertension due to hepatosplenic schistosomiasis, the patent paraumbilical vein, with hepatofugal flow, diameter > or = 0.68 cm and mean flow velocity > or = 18.41 cm/seg...