The venous flaps: an experimental study of the microvascular architecture, the area of perfusion and their correlation.

The aim was to compare the various modes (cephalic, caudal and bidirectional input) of venous-flap perfusion and to relate the area perfused to the microvascular architecture of the venous flaps. Thirty-three flaps harvested from the forearm and dorsal foot regions of 12 fresh cadavers were divided into four groups: Group 1, cephalic input (n = 12); Group 2, caudal input (n = 11); Group 3, bidirectional input (n = 13 - converted from either Group 1 or Group 2); and Group 4, a control group made up of traditional arterial free flaps (n = 10). Perfusion was carried out using a cocktail of vital dye and Roentgen contrast medium, so that the flaps could be studied both for area of perfusion and by microangiography. Perfusion in Groups 1 and 2 was carried out with increasing numbers of injected veins. The numbers of contrasted vessels in the microangiograms were counted and correlated with the areas of perfusion. Statistical comparisons were made between the different groups, between the test groups and the control group, and between the flaps from different anatomical locations. The bidirectional-input flaps showed statistically significantly larger areas of perfusion than both the caudal-input and the cephalic-input groups. The perfusion areas of the cephalic-input flaps were larger than those of the caudal-input flaps. The control flaps had the largest area of perfusion. Forearm flaps had larger areas of perfusion than dorsal foot flaps. There was a significant correlation between the area perfused and the number of vessels contrasted in all the venous flaps, with a significant increase in perfusion area with increasing numbers of veins.