Correction of extrahepatic portal vein thrombosis by the mesenteric to left portal vein bypass

Abstract

Objective: The goal of this study was to determine the effectiveness of mesenteric vein to left portal vein bypass operation (MLPVB) in correcting extrahepatic portal vein thrombosis (EHPVT) in children. The treatment of idiopathic EHPVT has been primarily palliative, whereas MLPVB restores hepatic portal flow in patients with EHPVT.

Methods: Thirty-four children with symptomatic EHPVT underwent surgery with intent to perform MLPVB and were followed for up to 7 years. MLPVB was successful in 31 patients (91%), all of whom maintain patent vein grafts and have symptomatic relief of EHPVT in follow-up. All patients had complete relief from gastrointestinal bleeding. Patients with hypersplenism had significant increases in platelet and leukocyte counts and reduction in spleen size. Superior mesenteric vein flow increased from 119 +/- 66 mL/min before bypass to 447 +/- 225 mL/min (P < 0.0001) after surgery. Postoperative blood flow in the bypass graft expressed as a fraction of calculated ideal portal flow for size correlated inversely with age (P < 0.001). Left-portal vein diameter increased from 2.6 +/- 1.6 mm to 7.3 +/- 2.4 mm 2 years after surgery (P < 0.002). Liver volume increased from 703 +/- 349 cm3 to 799 +/- 351 cm3 1 week after surgery (P < 0.001). Prothrombin time improved to normal in all patients 1 year after surgery.

Conclusions: MLPVB provides excellent relief of symptoms in children with idiopathic EHPVT and results in liver growth and normalization of coagulation parameters. This surgery is corrective and should be done at as early an age as possible.

FIGURE 1. A, Conventional angiography usually failed to demonstrate the size or presence of an intact intrahepatic portal vein because the contrast filled the cavernous transformation (CVTP) in the hilum of the liver or flowed into the coronary vein (G). B, Magnetic resonance (MR) or computed tomography (CT) angiography usually demonstrated and allowed precise measurement (2.5 mm) of the portal vein diameter in the left lobe of the liver as indicated here by the dotted line.

FIGURE 2. Blood flow measured by flow probe superior mesenteric vein (SMV) before mesenteric vein to left portal vein bypass operation (MLPVB) and in the vein graft into the Rex recessus (Rex flow) after completing the operation. Mesenteric flow was significantly increased by MLPVB (P < 0.0001).

FIGURE 3. An example of the attenuation of the intrahepatic portal venous tree as observed in most of the patients in this series. This intraoperative portal venogram was obtained by injecting contrast into the patent umbilical vein. The left portal vein (arrow) measures 2 mm in diameter where the vein will be opened within the Rex recessus to perform the MLPVB anastomosis.

FIGURE 4. The diameter of the left portal vein diameter in the Rex recessus was measured by Doppler ultrasound. The diameter increased progressively over time after MLPVB (P < 0.005, ANOVA).

FIGURE 5. Flow in the bypass expressed as a proportion of calculated ideal portal vein flow is plotted against the age of the child at surgery. A significant inverse correlation between flow achieved and the age of the patient suggests increasingly poor compliance of the intrahepatic venous system over time (P < 0.001).