Shunt-Restricted Arterialized Venous Flaps Mimicking Arterial Flaps in Microcirculation: Observations in Sprague-Dawley Rats

Abstract

Introduction: An arterialized venous flap is not a physiologic flap which is nourished through arterial system. Several surgical techniques have been reported to improve the flap survival, but venous congestion and inadequate peripheral perfusion were frequently encountered which limited the generalization of flap. Suzuki ligated the arterialized central vein of the rabbit ear to investigate the influence of the competent ”valve”. They did not extrapolate the mechanism of flap survival. Aim and objectives: Our hypothesis is interruption of the flow-through arterialized vein not only makes the arterial flow circumventing the clamp to perfuse the peripheral area but also decreases venous pressure for better drainage. In this study, we conducted a rat experiment to compare the microcirculation of abdominal adipofascial arterialized venous flaps with and without restriction of the arterialized vein. Materials and methods: Six male Sprague-Dawley rats were used for microcirculation observation. Each adipofascial flap based on left thoracoepigastric vascular system was prepared and observed following the sequence of arterial flap, shunt-restricted arterialized venous flap, and flow-through arterialized venous flap. Microcirculation was observed and recorded under vital microscope with a 100X-magnification, which is composed of a Nikon microscope MM-22 and a Sony Trinitron video monitor. Results: In the flow-through arterialized venous flap, the flow in the flap was slowly to-and-fro in both arterioles and venules without a dominant direction. In the shunt-restricted arterialized venous flaps: at the proximal flap, the flow in the smaller vessels was constant and slow and the flow in the trunk vessels ran swiftly and stopped intermittently towards the periphery of the flap; at the middle flap, the flow moved slowly and constantly from proximal toward distal flap in both arterioles and venules; at the distal flap, the directions of the flow within the arterial and venous networks were similar to the flow observed in an arterial flap. Conclusion: In rat abdominal adipofascial arterialized venous flap model, we observed the interruption of arteriovenous shunting not only made the blood flow circumventing the ligated site to nourish distal part of flap, but also made the flow of arterial and venous system of the arterialized venous flap directionally moving from proximal toward distal part of flap.