[Establishment of hemodynamic model of human radial forearm free flap].

Purpose: To preliminarily establish a hemodynamic 3D numeric model of radial forearm free flap with vascular pedicle of radial artery and vein, and discuss its scientific workability.

Methods: The 3D geometric model of 50mm×80mm×10mm radial forearm flap was established by Pro/E(Wildfire 4.0). The vascular pedicle was 50mm in length including radial artery (inside diameter was 1.9mm) and concomitant radial vein (inside diameter was 0.84mm). The half-embedded vessels went hrough the flap paralleling the long axis. Then the established geometric model was transferred to the SC/Tetra 8.0 software for mesh generation and calculation. According to the virtual flow volume of the radial artery, the inlet velocity was set as 20mm/s. With the different blood pressure of 53mmHg between the feeding artery and draining vein, the tentative porous values were achieved. Then porous model was applied to the flap to simulate the capillary structure. The pressure distribution on the central axis of radial artery and vein and the radial velocity distribution in three different cross sections of vessels were figured out.

Results: A model with 10355473 meshes and 2104014 nodes was built. When porous model was applied, the pressure difference between radial artery and vein was calculated to 7050 Pa (52.8mmHg), which was close to clinical value. The computational fluid dynamic analysis results showed that with porous model, the central pressure of radial artery was continuously kept to a higher level. When blood flowed in and flows out of the flap, the blood velocity decreased and increased greatly. While the central pressure of radial vein significantly decreased at the moment of blood flowing out of the flap. These results basically agreed with the features of normal blood circulation of the forearm flap.

Conclusions: Porous model effectively simulates hemodynamic status of forearm flap, which provides a new method for the study of mechanism of blood circulation in radial forearm flap and also lays a foundation for the following hemodynamic study of vascular anastomosis.