Vein Suturing Results in Worse Lung Graft Outcomes Compared to the Cuff Method.

BACKGROUND: The rat orthotopic lung transplant model is not widely used yet because of the complexity of the procedure, in particular, venous anastomosis. Here, we performed a rat orthotopic lung transplantation using either the suture (ST) or cuff (CT) method for vein anastomosis. OBJECTIVES: To compare the vein ST and CT techniques in terms of operative time, success, recipient survival, and early histological outcomes was the objective of this study. METHODS: A total of 24 left lung transplants in rats were performed. Twelve syngeneic (Lewis to Lewis) and 12 allogeneic (Brown-Norway to Lewis) lung transplants were performed using either the vein ST or the CT procedure. Arterial and bronchial anastomoses were performed with the CT technique. Graft histological damage was evaluated 3-7 days post-transplant in all rat lungs. RESULTS: The surgical success rate was 75% in both the ST and CT groups. Failures related mainly to vein bleeding (n = 2 in the ST group) and thrombosis (n = 1 in the ST group; n = 2 in the CT group). Total ischemia time was longer in the ST group (122 ± 25 min in ST group vs. 83 ± 10 min in CT group, mean ± SD), due to prolonged warm ischemia time (60 ± 12 min in the ST group vs. 21 ± 5 min in the CT group, mean ± SD), reflecting the time required to complete the vein ST procedure. The prolonged warm ischemia time resulted in significantly higher vascular inflammation in syngeneic grafts (2.3 ± 1.2 ST group vs. 0 in the CT group, mean ± SD) and in increased severity of ischemia/reperfusion injury and acute graft rejection (3.6 ± 0.4 in the ST group vs. 2.6 ± 0.4 in the CT group, mean ± SD) in allogeneic lung transplants. CONCLUSIONS: The vein ST technique is a more time-consuming procedure than the CT method and the prolonged anastomosis time has a deleterious impact on transplant outcomes. These findings suggest that warm ischemia time - one of the modifiable transplant factors - should be considered a major risk factor in lung transplantation, particularly in the setting of donation after cardiac death.