Cardiovascular catheter stiffness – a static measurement approach

Abstract Catheters are widely used for therapeutic and diagnostic purposes in various medical applications. Along with frictional properties as well as the catheter profile the catheter stiffness mainly affects the deliverability and thus, the handling properties of the catheter. Within this study the bending stiffness of proximal and distal catheter samples was investigated with a custom made test setup. In particular, the influence of the catheter clamping length on the test results is discussed. Bending stiffness was calculated directly from the measured force, deflection and clamping length considering the test setup compliance. Measurements were performed three times at five positions in circumferential direction. Measured bending stiffness ranged from 629 ± 31 Nmm² to 733 ± 58 Nmm² for the proximal samples and from 30 ± 5 Nmm² to 98 ± 30 Nmm² for the distal samples, respectively. Bending stiffness varied depending on the free catheter length and the reaction force measured. The maximum reaction force decreased with increasing free catheter length leading to a higher measurement uncertainty. However, when considering the same free catheter length quantitative results were similar within the group of proximal and distal samples, respectively.