OPS-imaging der humanen hepatischen Mikrozirkulation nach orthotoper Lebertransplantation

Abstract

Disturbances of the hepatic microcirculation are a main pathophysiological factor of ischemia and reperfusion injury (I/R) resulting in delayed graft function following liver transplantation. The present study aimed to analyze sinusoidal perfusion in the course of clinical full-size liver transplantation utilising the orthogonal polarization spectral (OPS)-imaging technique, which enables, like in intravital fluorescence microscopy, the direct observation of the sinusoidal blood flow. A total of 27 patients was examined. For transplantation, in all grafts a simultaneous reperfusion of the hepatic artery and the portal vein was performed. In all patients a veno-venous bypass was performed. The mean cold ischemia time for the preservation in UW solution was 555 ± 205 min, the mean anhepatic period 82 ± 29 min. Sinusoidal perfusion was analyzed 5 and 30 minutes following reperfusion on both liver lobes. Quantification of the microcirculatory parameters was performed off-line by using a computer-assisted image analysis system as were the sinusoidal diameter (D), red blood cell velocity (RBCV), and the functional sinusoidal density (FSD). The sinusoidal volumetric blood flow (BVs) was calculated from the sinusoidal diameter and the red blood cell velocity (BVs = π /(D/2)2×VRBCV). The results were then compared to the baseline microcirculation after laparotomy of 21 living donors for living related liver transplantation, which were considered of representing the physiologic hepatic microcirculation of a human liver. Typically for reperfusion injury, manifestation of red blood cell sludging, sinusoidal perfusion stasis, and erythrocyte extravasation was observed in the early course following transplantation. Compared to the baseline microcirculation, the sinusoidal diameter and the sinusoidal volumetric blood flow were significantly increased, the functional sinusoidal density and the red blood cell velocity significantly decreased. For the first time, OPS-imaging enabled direct visualization of postischemic hepatic microcirculation following full-size liver transplantation in humans. Both 5 and 30 minutes after reperfusion a sinusoidal perfusion deficit compared to baseline liver microcirculation was observed. The increase of the diameter and the volumetric blood flow by the means of a reactive hyperemia within the perfused sinusoids represent a typical postischemic reaetion. Taken together, OPS-imaging enabled the objectivation of the sinusoidal perfusion in the course of liver transplantation, which may be crucial for treatment strategies of ischemia/reperfusion induced injury.