Impact of preserved collateral veins on small-for-size grafts in living donor liver transplantation.

AIM: Graft size is a critical issue in living donor liver transplantation (LDLT). We hypothesized that too much portal flow could possibly be diverted into pre-existing collateral veins, alleviating small-for-size syndrome (SFSS) in LDLT. This study evaluated the impact of the preserved collateral veins in the outcomes of LDLT using a small-for-size graft. METHODS: For patient safety, a graft-to-recipient weight ratio (GRWR) <0.8% was strictly confined to patients with collateral veins (group A), and the patient group was compared in a 1:3 ratio to a matched group of patients with GRWR ≥0.8% (group B) using propensity score analysis. RESULTS: Forty and 120 patients were included in group A and B, respectively. No significant differences in baseline patient characteristics were observed between the two groups except for graft weight and GRWR. The lowest GRWR was 0.4%. The graft portal inflow showed no significant differences for 7 days after graft implantation, ranging from 1668 to 5100 mL/min. Small-for-size syndrome occurred in no patients (0.0%) in group A and in 10 (8.3%) in group B (P = 0.067). Overall survival rates at 1, 3, and 5 years were not different between the two groups (85.0%, 82.5%, and 82.5% vs. 92.5%, 86.7%, and 85.0%, respectively; P = 0.670). CONCLUSION: Pre-existing collateral veins saved during surgery may have a reserve buffer for excessive portal flow to obviate SFSS in LDLT.