In vivo assessment of the hepatic microcirculation after mesenterico-portal bypass (REX-shunt) using orthogonal polarization spectral imaging.

Background: Extrahepatic portal vein thrombosis, not associated with cirrhosis or tumours, is the second most frequent cause of portal hypertension worldwide. Especially in children, anatomic mesenterico-portal interposition (REX-shunt) has become an established treatment. The changes in hepatic microcirculation after reperfusion of the shunt have not been investigated so far.

Aims: This study investigates the hepatic microcirculation before and after REX-shunt interposition using orthogonal polarization spectral imaging (OPS).

Patients And Methods: Since 2004, three consecutive patients with extrahepatic portal vein thrombosis underwent REX-shunt interposition. We measured the hepatic microcirculation by OPS before and directly after REX-shunt reperfusion and analysed the capillary vessel diameter, red blood cell velocity, functional capillary density and volumetric blood flow. Furthermore, we compared our values with the physiological values of the hepatic microcirculation defined previously by other investigators.

Results: All shunts showed an excellent function in the follow-up investigations. The intra-individual microcirculatory analysis revealed a reduction in the red blood cell velocity after shunt reperfusion in particular.

Conclusions: Our results provide preliminary evidence for the reversal of the hepatic arterial buffer response following the restoration of the portal venous blood flow. This may be a short-term effect because of the restored portal venous blood flow.