凍結手術における温度依存性を考慮した一次血栓形成モデリング

抄録

Cryosurgery is a treatment for cancer which destructs cells by freezing. In cryosurgery, cells are injured not only by freezing but also by vascular stasis. The vascular stasis caused by thrombosis necrotizes the surrounding non-targeted cells due to the lack of oxygen and nourishment. Inhibition of thrombus formation, the former phase of the vascular stasis, is required to prevent damaging normal cells around a tumor. By analysis of thrombus formation under low temperature, the temperature controlling method can be developed to form less thrombus. Foregoing studies simulate platelet aggregation based on distance between platelets. However, in cryosurgery, temperature dependency of blood-clotting factors' activity is required to be considered. The authors constructed a model consisting of vascular and extravascular tissues. The temperature distribution near the ice probe and vessel is simulated by using the finite difference method solving the energy equation. The cell necrosis areas were estimated by considering the freezing rate of water in the vascular endothelial cells. We also constructed a model considering the temperature dependency of bonding probability and simulated platelet aggregation to cell necrosis areas. The bonding between platelets is represented as a spring and a damper. The simulation with varied temperature around destructed area showed that platelet aggregation depending on temperature. By comparing simulation result with experimental data, it is suggested that the proposed model can represent thrombus formation.