Design and Evaluation of the Epsilon Catheter

Abstract

Objectives – Over the past decades, more and more cardiac diseases have been treated in interventional cardiology. Catheters are generally used to access the heart through the blood vessels. The previously developed steerable Sigma catheter at Delft University of Technology, tackles cable related challenges of conventional mechanically controlled catheters by an improved tip and shaft design. With its two finger-controlled joysticks, the handle allows full actuation of the four degrees of freedom catheter tip. However, this input control method is not specifically designed for optimal user experience. Therefore, the aim of this research is to design an input control method for the Sigma catheter tip and shaft design to improve task performance while reducing workload for the interventionist. Methods – A theoretical framework was composed and analysed to form design requirements. After detailing the functional and geometrical design, a functional prototype, the Epsilon catheter, was fabricated. To evaluate the proposed control method, an experimental setup was prepared and the control method of both catheters were compared. Six participants were asked to conduct the task, which consisted of contacting targets with the catheter end-point. Target-to-target times were measured and a self-report questionnaire was conducted. Results – The theoretical analysis was divided in the interventional environment, the interventionist who controls the catheter, and the instrumentation. A functional design was made, including catheter control through combining multiple fingers and the wrist using positive input-output coupling. The geometrical design achieved these functionalities through bending flexures and a 180° bended shaft. Data analysis of the experiment showed differences in target-to-target times and self-reported measures. Conclusion – The Epsilon prototype showed to fulfil on the requirements in a functionality test. The prototype allows steering the catheter tip in five degrees of freedom, single-handed in a handheld design. In the experimental setup, participants using the control method of the Epsilon catheter, performed the targeting task faster than using the Sigma catheter with reduced workload. Significance – Allowing the interventionist to control all manoeuvrability of the catheter tip single handed, may change the operational procedure during interventional cardiology. A single interventionist could perform extended treatment using two individually controlled multi-steerable catheters. Further developments will be towards design optimisations to further improve user experience and evaluation of the fifth degree of freedom.