Microvenous grafts less than 1 mm in dimameter are now used routinely to replace the arterial defects in replantation surgery and electively to gain pedicle length during free tissue transfers. It is often difficult during operations to determine the correct length of vein graft required.. Excessive graft tension narrows the lumen while tortuosity allows kinking, both of which are thought to decrease patency.
This study was. undertaken as follows, to examine the physiological and hitological properties of 60 rabbits´ femoral vessels and the interposed vein grafts.
1. Femoral vessels were divided a distance 0. 0, 1. 0, 1. 5, 2.0, 2.5, 3.0, 4.Ocm respectively, and the con-
tracted length of vessels excised and the distance, between the retracted vessel ends were measured.
2. Various lengths of femoral vein grafts were used to icm defects in the ipsilateral femoral artery in
attempt to determine the correct length of vein graft and to estimate its patency rate.
3. Histological examinations and scanning electrion microscopic studies of the interpositional vein grafts
were combined to see their morphological changes.
Results obtained were as follows.
1. Harvested venous segments were found to contracted more than arteial segments, shortening by about 35-50 "No of their in vivo length, but excised arterial, segments contracted by approximately 35% of their vivo´ length.
2. The retraction of divided venous and arterial ends is approximately the same.
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3. When a 2.0cm vein graft was used to bridge the 1.0cm arterial defect, patency improved to 100%
I Long redundant grafts were initially tortuous and dilated, but lost their redundancy and dilatation i
when studied 4 weeks later.
4. Histologically, arterialized vein grafts thickened by accumulation of fibrous tissue in the medial layer and intimal proliferation.
5. Scanning eletron microscopic studies showed endothelial changes in vien grafts arterialization; The
vien graft´ endothelium was arranged in longitudinal folds resembling those seen in normal arteries.
Conclusively, when a 1.0cm arterial gap was bridged with the 2.Ocm interpositional vein graft, patency improved to 1001/c. As the length of the arterial defect increased more than 3.Ocm in length; the ideal inter-positional Microvenous grafts should be approximately 357o longer than the arterial defect to permit optimal balance be tween. linear and radial deforming forces.
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