Intimal fibrosis (phlebosclerosis) in the saphenous vein of the lower limb: a quantitative analysis.

The influence of pre-existing phlebosclerosis on the patency rate of aorto-coronary bypasses is uncertain. To examine this influence, extensive quantitative histological investigations of the intimal thickness of the left saphenous vein were made in 30 cases. In almost all veins the intima was thickened by collagen and elastic fibres as well as by fusiform cells which were assumed to be smooth muscle cells. The innermost layers also contained increased collagen adding to the intimal thickening. Three different methods to measure the intimal thickness were tested morphometrically: planimetric, a four-point method and a so-called method of estimate. The latter is the most time-saving and effective method. The average intimal thickness showed considerable deviations, but the intimal thickness in individual veins did not deviate greatly. As a rule, a specimen with an intimal thickness of less than 100 microns belonged to a vein with mild or moderate intimal thickening, but specimens with an average intimal thickness of 100-250 microns usually derived from a vein with moderate or pronounced intimal fibrosis. However, extreme values allowed a more precise statement to be made. A specimen with a nonsclerotic intima suggested at best a mild intimal fibrosis of the vein in the lower limb, whereas a specimen with marked intimal thickening derived from a vein with severe phlebosclerosis.