Viscoelastic properties and collagen content of the long saphenous vein in normal and varicose veins.

Veins taken from patients undergoing surgery for varicose veins were compared with those obtained from patients undergoing other surgical procedures ('normals'). Varicose veins had a lower breaking strength and breaking energy than normal veins. Elastic stiffness was less in normals (tan theta = 41 (24] than in varicose veins (tan theta = 55 (18); P less than 0.01). There was no difference in viscoelastic behaviour between samples taken above, at, or below the valve leaflet insertion. In normals, perivalvular vein wall exhibited a 50 per cent lower breaking strength and elastic stiffness than vein from other sites. Collagen content was significantly higher in normal vein specimens in all sites examined (mean collagen content = 70 (21) micrograms/mg, versus 51 (20) micrograms/mg for varicose veins; P less than 0.001). We conclude that significant structural changes are seen in varicose veins. In normal veins, the perivalvular vein wall has distinct viscoelastic features when compared with vein wall from other sites. This difference was not found in veins which became varicose.