Vasospasm of the flap pedicle - the new experimental model on rat

An experimental model for testing vasodilating drugs on vasospasm caused by standardized traumatisation of a pedicle has not been described yet. The aim of this study was to develop such model and to compare the effects of different types of surgical manipulations that can provoke vasospasm during flap dissection.

The pedicled groin flap was dissected in 185 male Wistar rats under standardised conditions. The blood perfusion curves of the flap were obtained using the Laser Doppler flow-meter. The vasospasm was provoked by the following manoeuvres: pulling on the pedicle; compression of the pedicle by vascular clamps; dissection of the vessels and by presence of blood around the pedicle. The perfusion recording curves were processed and two important time periods describing the progress of spasm were extracted. Combined non-parametrical ANOVA and WILCOXON tests were used to compare the time parameters between the groups. On the basis of statistical evaluation, we divided the factors responsible for vasospasm into categories labelled as strong and weak. The strong stimuli included dissection of the vessels; pulling on the pedicle using 15g, 20g and 25g weights and presence of blood around the pedicle. The weak stimuli included compression of the pedicle using vascular clamps and pulling on the pedicle using 10g weight. Pulling on the pedicle using 15g weight was chosen as the most appropriate stimulus for the experimental model.

A new experimental model for studying vasospasm caused by tension on the pedicle was developed. This model is well defined, easily repeatable and reproducible, produces vasospasm of appropriate duration and permits standardized topical application of vasodilating drugs.

The finding that certain kind of surgical traumatisation causes vasospasm that is longer than the others may help microsurgeons to review their methods of surgical manipulation.