A novel in vivo technique for observations of choke vessels in a rat skin flap model.

Background: Choke vessels are reduced-caliber vessels that link adjacent vascular territories throughout the body. The behavior of choke vessels determines flap survival. Therefore, it is important to develop a reliable technique with which to study these vessels. The purpose of this report is to document a novel in vivo technique for the study of choke anastomotic vessels in a rat skin flap model. Methods: This study was divided into two parts. In part I, 30 adult Sprague-Dawley rats underwent whole-body lead oxide/gelatin injection and the skin was removed for radiography to analyze the skin vasculature. In part II, a dorsal skin flap was elevated in 12 rats, and a skinfold chamber was installed to observe the choke vessels between the iliolumbar artery perforator and the posterior intercostal artery perforator for 8 days. Evans blue dye was injected through the lateral tail vein. Blood flow velocity was calculated. Results: In part I, three distinct patterns of dorsal cutaneous vasculature were found. A three-territory, 3.5 x 10-cm flap can be elevated on the dorsum of the rat. In part II, an increase in diameter of the choke arteries and the choke veins was observed, particularly in the fine venules. Blood flow velocity across the arterial segment of the choke zone was found to be 2.5 mm/second. Conclusions: The observation chamber technique for in vivo study of the choke anastomotic region of the rat dorsal skin flap model is a promising novel method for studying skin microcirculation. The time sequence of microvascular events in the choke anastomotic zone of this rat model was documented. (Plast. Reconstr. Surg. 130: 308, 2012.)