Influence of Perioperative Storage Solutions on Long-Term Vein Graft Function and Morphology

It has been shown that suboptimal preparation of a vein graft prior to its insertion results in immediate morphologic and functional damage to the endothelial cells but not to the underlying smooth muscle cells. However, little is known about whether such perioperative injury to the vein grafts influences the subsequent development of intimal hyperplasia and smooth muscle cell contractility. This study examines the influence of storage in saline solution or Ringer's lactate on the development of intimal hyperplasia and vasomotor function in experimental vein grafts. Twenty-six New Zealand white rabbits had a carotid vein bypass graft performed after the veins had been immersed (15 minutes) in either heparinized saline solution (Sal; n = 13) or Ringer's lactate (RL; n = 13), and each group was harvested after 28 days for either histologic (n = 8) or functional studies (n = 5; four 5 mm rings/graft). Saline storage of the vein graft resulted in a 38% increase in the thickness of the intimal hyperplasia (113±2 vs. 83±2 μm, Sal vs. RL; mean±SEM;p<0.05)without a change in medial thickness (87±5 vs. 86±8 μm, Sal vs. RL;p>0.05). The two sets of vein grafts showed no difference in sensitivity to norepinephrine, serotonin, and bradykinin. The standardized maximal contractile forces (maximal contraction/contraction to 60 mmol/L KCl; mean±SEM) to serotonin (0.88±0.11 vs. 0.52±0.07;p<0.01), and to bradykinin (1.65±0.15 vs. 0.37±0.13;p<0.01)were increased in the vein grafts stored in saline solution compared with those stored in Ringer's lactate. Norepinephrine responses were unchanged (1.32±0.12 vs. 1.57±0.20;p>0.05). Saline storage of the vein graft results in the increased development of intimal hyperplasia with an overall enhanced contractility but without changes in agonist sensitivity. This study places further emphasis on the need for good perioperative care of the vein bypass graft because it results not only in the previously documented short-term problems but also in long-term structural and contractile changes that may contribute to decreased graft patency.