In order to reduce the operative injury of the endothelium in free reversed vein grafts, cultured human endothelial cells were used to test the optimal concentration of the constituents of a
flushing solution for improved protection of the endothelium. The following
solution proved to be the most suitable when tested at 20 degrees C;
mannitol 160 mmol l-1,
glucose 15 mmol l-1, NaCl 30 mmol l-1,
KHCO3 5 mmol l-1, K2SO4 10 mmol l-1, KH2PO4 4 mmol l-1, MgSO4 20 mmol l-1, CaCl2 1.5 mmol l-1,
potassium citrate 1.0 mmol l-1,
Pluronic F-68 20 mg l-1,
HEPES 4 mmol l-1,
HEPES-Na 6 mmol l-1, pH 7.25, osmolality 325 mosmol kg-1 H2O. When endothelial cell injury was measured by a 51Cr-release assay, the new
solution protected human endothelial cells in culture during hypothermic incubation better than isotonic NaCl, St Thomas'
cardioplegic solution or Krebs-Henseleit's
buffer. Transmission and scanning electron microscopy showed that the endothelium of human saphenous vein grafts was well preserved following 6 h of incubation at 20 degrees C with the new
solution. As determined by morphometry using scanning electron microscopy, the endothelium of free porcine vein grafts was better preserved after incubation for 2 h at 20 degrees C with the new
solution than with either isotonic NaCl (p = 0.02) or diluted, heparinized blood (p = 0.02) as the incubation medium, all cases observed following 2 h of subsequent arterial flow. The present study indicates that the endothelium of free vein grafts can be well protected against
hypothermia when the
flushing and irrigation fluid has a composition favouring endothelial protection. It appears likely that such treatment of vein grafts will reduce the frequency of vein graft narrowing and occlusion, post-operatively.