Catheter ablation is the preferred minimally invasive treatment for cardiac arrhythmias. Limited maneuverability of currently available catheters undermines the success of this treatment and subjects operations to prolonged repeated attempts to pace suspicious zones and ablate the arrhythmogenic substrates under ionizing radiation of fluoroscopy. To compensate for such inefficiencies, a control system that can replace operator's hand during the procedure is desired. This system should be able to direct catheter tip toward the ablation site and maintain its contact with the substrate during ablation, accelerating the process and enhancing its precision. To realize such a system, the first step is to kinematically model the catheter and to devise a control strategy to embed the kinematics of the catheter. This paper proposes a simplified approach to model and control a general single-segment active catheter as a continuum robot. In this approach, the flexible catheter is modeled as a rigid manipulator having coupled joints. Utilizing the structural coupling of the catheter, joint-variables are reduced to actuatable parameters thus lifting some of the mathematical difficulties in formulation of a control strategy for redundant manipulators. The modeling is validated through experiments with a typical steerable ablation catheter equipped with an electromagnetic tracker in vitro.
In this paper a novel method is proposed for live endocardial boundary identification. The goal is to achieve an optimal solution to the problem of real-time automatic detection and tracking of endocardial border in ultrasonic image sequences acquired through Intracardiac Echocardiography (ICE). Border identification of 2D ultrasonic images, which normally consists of a number of stages namely preprocessing, segmentation, detection and visualization of the border, is a cumbersome task. ICE's potential in guidance of minimally invasive interventions requires online boundary detection of its inherently less speckled images. Numerous studies have addressed this issue in echographic images by proposing various methods applicable at each stage. With this repository of methods available, a comparative study is performed on single-image segmentation approaches. An algorithm based on order-statistics operators is proposed to achieve fast border delineation in a sequence of images. This method can outperform other approaches in terms of time and robustness, and does not require user interaction.