Evaluation of Mechanical Properties of Catheter Shafts under Cyclic Bending

抄録

Catheter intervention is used for the treatment of various diseases inside the body. This non-surgical technique is widely used because of its clinical and economic benefits. Although the mechanical properties of a catheter shaft are important to conduct operations using catheters safely, there is no standard testing method for the mechanical properties of the catheter shaft. In this study an evaluation method for the mechanical properties of the catheter shaft under cyclic bending was proposed. Cyclic bending tests were conducted to compare mechanical properties (radial strength and resistance of buckling) of three kinds of specimens. One is the outer layer of the catheter shaft, and the other two are a steel-ribbon catheter shaft and a W-ribbon catheter shaft. Load difference defined by the maximum load of each cycle was used to decide the buckling displacement. Additionally, finite element analysis (FEA) was performed to analyze the deformation behavior of the catheter shaft during a three-point bending test. The load-displacement curves obtained from the FEA showed a good agreement with the envelope of the load-displacement curves in the experiment. It was also revealed from FEA that the deformation behavior of the catheter shaft at the loading point was different from the material of the wire mesh in the catheter shaft. These results suggest the radial strength of the wire mesh increases the buckling displacement of the outer tube and enhances the buckling strength of the catheter shaft. These results also showed that the W-ribbon catheter shaft demonstrated the highest load resistance and the highest buckling displacement. Thus, it was shown that the proposed experimental procedure based on the cyclic bending tests was effective to compare the mechanical properties of various catheter shafts.