Hemodynamic and Geometric Factors in Flow-Through Chain-Linked Double Free Flap Reconstruction: A Critical Analysis.

Complex head and neck defects requiring double free flap reconstruction present unique challenges in vascular design. Flow-through configurations, where one flap's arterial supply feeds a second flap, offer theoretical advantages but create inherent vulnerabilities. This seminar examines the hemodynamic and geometric principles underlying flow-through reconstruction, analyzes common failure mechanisms, and provides practical guidelines for surgical decision-making. Key concepts include retrograde thrombus propagation, cumulative pressure drops in series circuits, and the non-Newtonian properties of blood that complicate theoretical predictions. Understanding these principles is essential for appropriate patient selection and technical execution in complex reconstructive cases.