Hemodynamic Remodeling Mechanism And Pathophysiologial Correlate In Rat Hepatic Vein Outflow Obstruction

Aim hepatic venous obstruction is not uncommon with the development of livingdonor liver transplantation and extended liver resection with transaction of the majorhepatic vein. This leads to focal congestion in the graft or remnant liver. Thehemodynamic change and the prognosis of the focal congestive area is unclear. Thisstudy aims to characterize the focal hemodynamic change and pathophysiologialcorrelate in different hepatic lobes with outflow obstruction and its course of recoveryin rat model.MethodPart1: Rat livers were divided into3different areas. Ligation of the left hepatic veinwas implemented to induce congestive area in isolated lobe （IL）， and Ligation of theright median hepatic vein in non-isolated lobe （NIL）. Meanwhile, The right superiorlobe was chosen as the normal control area. Staining agent was injuected into thecongestive area to visualize the hemodynamic remodeling process in relation topressure gradients. The flux value （FV） and the oxygen saturation （SO₂） ofmicrocirculation was monitored before euthanasia on post-operation0.5,12,24,48,96,168, and336hours. The hepatic damage and Suzuki’s score were evaluated.Part2: Rats liver were divided into3different areas. Ischemia reperfusion （IR） area:the inflow of the right superior lobe was clamped for half an hour. NIL-congestivereperfusion （CR） area: the outflow of the right median lobe was clamped for half anhour. IL-CR area: the outflow of the left lobe was clamped for half an hour. The FV andthe SO₂of microcirculation was monitored before euthanasia on post-operation0,24,72, and168hours. The hepatic damage and Suzuki’s score were evaluated.ResultPart1: There were no significant differences in average FV and SO₂among normallobes and no statistically difference in multiple comparisons between different lobes. No significant correlation was observed between FV and SO₂in normal lobes. The blood ofnormal lobes flowed out through the hepatic vein. In NIL, the congestive area recoveredspontaneously by the formation of vascularized sinusoidal canal （VSC）. But in IL,congestive area cannot recovered spontaneously by the formation of hepatofugal portalflow （HPF）. The FV of NIL congestive area increased gradually, while the bloodperfusion of IL congestive area show undulation of declining first and then rising. TheSO₂of NIL congestive area rises first and then decline. Meanwhile, The SO₂of ILcongestive area increased gradually. In both the NIL and the IL congestive area, SO₂increased with FV.Part2: Compared to IR，CR reduced FV and SO₂more significantly. However, incomparison of IL-CR and NIL-CR area, no significant difference was found. Afterloosening the clamp, each area of the liver can recover spontaneously. Compared withIR, CR would result in more severe liver damage in early postoperative period.However, there is no significant difference between NIL-CR area and IL-CR area. Afterloosening the clamp, each area of the liver an recover spontaneously.Conclusion When hepatic vein was obstructed，the FV and SO₂declined significantly,causeing severe liver damage. However, the prognosis of NIL congestive area wasbetter to that of IL. VSC was the main pattern of hemodynamic remodeling in NILcongestive area, while HPF was the main pattern in IL. Hepatic arterial perfusion isessential for the spontaneous recovery from focal hepatic venous outflow obstruction.The NIL could regain dual blood supply. Compared to the SO₂, the timely and sufficientmicrocirculation reperfusion was crucial in the spontaneous recovery of congestive area.However, despite of the timely and sufficient miscirculation reperfusion, CR can alsoinduce severe liver damage; Compared to the IR, CR could result in more severe liverdamage. In addition, the results of CR showed no significant difference between NILand IL.