Clinical endothelial damage during preparation of saphenous vein grafts is an important cause of early and late graft failure. The cause of endothelial injury during vein harvesting and preservation is complex. Hypothermia is thought necessary to
preserve cell viability but has been implicated in morphologic injury to the endothelium.
This study was initiated to investigate the relative role of cold(4℃) storage temperature on the endothelium injury of inferior vena cava of Wistar rat.
In these experiments, rats of Wistar strain, weighing 150 to 210 gm, were diwided into : normal control(n=5) group, 4℃preserved group(n=15), and 20℃preserved group(n=15).
When harvesting the vena cava, a piece length(4~5cm) was taken and divided in two equal parts.
In control group immediately after harvesting, vena cava segment were fixed for scanning electron microscope examination. The group preserved at 4℃saline was also subdivided into 3 groups : 15 minutes group(n=5) 50 minutes group(n=5) and
papaverine
mixed 50 minutes group(n=5).
The group preserved at 20℃saline was also subdivided into 3 groups : 15 minutes group (n=5), 50 minutes group(n=5) and papaverine mixed 50 minutes group(n=5).
The effect of profound(4℃) and moderate cooling (20℃), with or without mixing papaverine on the endothelium of the inferior vena cava segments of Wistar rat was compared.
The types of pathological damage observed included endothelial cell separation, endothelial cell loss, rater, exposed basement membrane, exposed fibrillar collagen, intimal edema, and medial edema. The damaged endothelial cells among the 100
cells
were
counted in the scanning electron microscope and the extent of damage was expressed on the basis of percent.
@ES The results were as follows :
@EN 1) In normal control group, well-preserved endothelial lining with cobblestone appearance was seen.
2) Frank partial erosion of endothelial lining, intercellular separation and exposure underlying subendothelial components were examined with 52.5% of cell damage in 4℃15minutes group. In 4℃50 minutes group, rolled-up appearance ofmost
endothelial
cells with severe desquamation and exposure of underlying subendothelial components were seen with 76.5% of cell damage.
3) Vein segments of 20℃15 minutes group showed no significant endothelial damage, and in 20℃50 minutes group, mild edema or flattened endothelium with partial erosion and adhesion of platelets were seen.
4) No significant endothelial disruption or detachment was seen with normal lining in 50 minutes papaverine-mixed group both of 4℃and 20℃saline with 5.5% and 5.0% of damaged cell respectively.
The vena cava segments that were exposed to 4℃had significantly higher degree of endothelial cell detachnment than those exposed to 20℃. But this cold-induced injury can be minimized if the vena cava segment is preserved in the solution mixed
with
papaverine.
The study indicates that cooling to 4℃may be harmful to the endothelial lining of veins which are prepared for grafting into the arterial system, and papaverine may works to prevent endothelial injury.
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