The vascular response of the "delay" procedure.
Delay of a flap apparently enhances its vitality during later transfer. At the present time, although we have a better understanding of the mechanism of skin flap delay, there are still controversies regarding the details. The purpose of our research was to study the vascular response of the delay phenomenon and compare the results with those obtained by others. This was accomplished by raising and delaying flaps in rats and histologically counting, at regular intervals, the number of arterioles, at a point of 2 cm distally to the base of the flap. Our data shows a decline in the number of arterio-venous shunts, from one week toward the third week post-operatively, thus sustaining those who advocate that the optimum time for transfer after delay procedure, is towards the third week. It is of empiric knowledge that a delay of a flap apparently enhances its chances for survival during later elevation, rotation, and transfer. Hynes (1) suggested that the reason for necrosis in the distal part of the flap is due to the opening of a significant number of arterio-venous shunts. The work of Reinisch (2) contributed to this idea by demonstrating a change in the microvascular circulation in the flap. In this work, an attempt is made to give further proof of Hynes' theory by counting histologically the number of arterioles during the delay period in a flap as an indication of the number of patent arterio-venous shunts.