Graft Inflow Modulation for Portal Hyper-perfusion in Live Donor Liver Transplantation: a Randomized Pilot Study

Due to shortage of deceased donor organs, LDLT (living donor living transplantation) is gaining importance all over world. Previous studies have showed poor outcomes with donor grafts having GRWR (graft to recipient weight ratio) < 0.8 due to development of SFSS (Small for Size Syndrome) where the graft is too small to meet the recipient's metabolic demands. SFSS is characterised by prolonged cholestasis, intractable ascites, prolonged INR and encephalopathy. However, it is not always possible to obtain larger graft from live donor owing to the risk's associated to donor. Various techniques have been developed in order to manage a smaller graft in recipient (ex: hemiportocaval shunts, splenic artery ligation, splenectomy). HPCS (hemiportocaval shunt) have been associated with risks of portal steal phenomenon and encephalopathy. Splenectomy is associated with increased risks of infections / sepsis and portal vein thrombosis postoperatively. Splenic artery ligation close to its origin is associated with least risks and is increasingly being used as the method of graft inflow modulation when required.

Recent studies have showed that Portal Flow Hemodynamics are more important than GRWR in predicting the occurrence of SFSS. Grafts whose GRWR is > 0.8 can also show features of SFSS after ruling out all other causes (5). Persistent portal hypertension leads to sinusoidal endothelial injury, haemorrhage, oedema and architectural distortion - these changes are more marked in SFS (small for size) grafts. Also, due to hepatic arterial buffer response, reduced flow in hepatic artery leads to further ischemic injury, cholestasis and ischemic cholangitis. A recipient portal venous flow of > 250 ml/min/100 grams of liver weight is defined as portal hyper perfusion.

H Y Ou et al retrospectively analysed data involving patients whose PVF > 250 ml/min/100 gr after reperfusion where 6 patients underwent inflow modulation (using splenic artery ligation) and other 2 didn't. They found that only 1 / 6 patients in those who underwent GIM developed SFSS where as both the patients who didn't undergo GIM developed SFSS (1 of them died). Also, none of the patients developed complications related to splenic artery ligation in their study.

Bhavin B et al in their retrospective study on 134 liver transplant recipients found that 19 patients met criteria for SFSS (as per Kyushu University). On analysis of the factors responsible for early graft dysfunction, only portal vein flow > 190 ml/min/100 gr of liver after reperfusion was found to be a significant predictor. GRWR was not significantly associated with graft dysfunction - 3 / 19 patients had GRWR < 0.8 while 16 patients in non-dysfunction group had GRWR < 0.8

Ogura et al retrospectively analysed data involving intentional portal pressure modulation when PVP (portal venous pressure) > 20 mm Hg. They found that the patients with a portal pressure < 15 mm Hg had better 2 year survival compared to those with > 15 mm Hg. Also, recovery from hyper bilirubinaemia and coagulopathy after transplantation was significantly better in those with PVP < 15 mm Hg.