Dimensional analysis of human saphenous vein grafts: Implications for external mesh support

Dimensional analysis of saphenous veins of 200 consecutive patients having coronary artery bypass grafting. Outer diameters were measured in situ during vein harvest at routine surgical syringe distension. Mean outer-diameter values are shown as a function of distance from the ankle. Error bars represent 95% confidence intervals. Vertical lines delineate statistically significant cut points between segments of different diameter (Tukey-Kramer honestly significant difference [HSD] test) with capital letters A through E indicating statistical significance. Regions not sharing identical capital letters are statistically distinct (P < .05).

Incidence of outer-diameter fluctuations and distances over which they occur. The dashed line represents the percentage of veins that experienced diameter changes of a certain magnitude (right-sided y-axis). The solid line shows the average distance over which these diameter changes take place (left-sided y-axis). Error bars represent 95% confidence intervals.

Distribution of side branches from the malleolus. Partitioning revealed a highly significant increase in the total number of side branches (solid line) between 22 and 32 cm from the ankle. When branches were categorized into large (dashed line), medium (dashed/dotted line), and small (dotted line) sizes, their densities followed a similar distribution pattern with a relatively equal incidence between the groups. Error bars represent 95% confidence intervals.

Histologic appearance of malleolar segments of human saphenous veins (black bar, intima; white bar, media; and gray bar, adventitia). Although the Masson's stains (left column/original magnification ×4 and middle column/original magnification ×10) allow us to distinguish between smooth muscle cells (red) and collagen (blue), Movat stains (right column/original magnification ×40) were chosen to distinguish intimal “cushions” from true neointimal hyperplasia. Glycosaminoglycans—typical for neointimal hyperplasia—would have stained blue. Their absence supports the interpretation that cushions are anatomic rather than pathologic structures. Typically, thick-walled veins (top row) have a high propensity for intimal cushions, whereas thin-walled veins (bottom row) generally have delicate intimas.