Expansion of venous flaps: an experimental study in rats.

In this study, the effects of controlled tissue expansion on the survival of unipedicled venous flaps were investigated in rats. In three groups of Lewis rats, a 3 x 6 cm unipedicled Lateral thoracic venous flap was studied with group 1 as control group (n = 30) without any manipulation, group 2 (n = 30) where an expander was introduced under the flap area but was not expanded and group 3 (n = 30) in which a 40 ml expander was introduced under the flap area and was expanded over a period of 10 days. Observations included gross and histological examination, reverse microangiography, reverse flow resistance and percentage of survival of flaps. Group 3 (expanded) showed more angiogenesis, a better delineation on microangiography, lower reverse flow resistance and higher survival rates as compared to group 2 (non-expanded). In the control group the survival rate of flaps was the poorest and the flaps showed higher rates of reverse flow resistance. Microangiography was not successful in the control group. In a pilot project prior to this experiment microscopic examination of the Lateral thoracic vein in 10 Lewis rats had confirmed the presence of two or three valves in this vein.