Catheters have been widely used to deal with heart valve diseases. However, the diversity in handle structures and bending curvatures imposes significant complexities in safe delivery and positioning. In this letter, we designed a module for single knob actuation assembled coaxially on the catheter handle, composed of a chuck for universal clamping of diameters from 15 to 45 mm and a position-adjustable shaft to accommodate various spacing between knobs. In addition, we proposed a two-curvature with pseudo joints (TC-PJ) model for bending control of bendable sections (BSs) in catheters. The verification was decoupled into two steps based on the other three deformation patterns. Firstly, comparing the two-curvature (TC) model with pseudo-rigid-body (PRB), constant curvature (CC), and Euler spiral (ES) models to simulate planar bending and elongation, the results showed a more accurate shape representation. Then, five distinct catheters were employed to test the clamping universality of the module and tip positioning precision of the TC-PJ model which took torsion and shear strain into consideration. The root-mean-square error (RMSE) and the standard deviation (SD) of tip position and direction were analysed. Results indicated the module's suitability for clamping these catheters, with the large guide sheath exhibiting minimal position RMSE (SD) of around 0.10 (0.051) mm and 0.049 (2.15) degrees, while the puncture catheter demonstrated the highest position and direction RMSE (SD) extending to about 1.16 (0.53) mm and 0.70 (31.33) degrees, primarily attributed to the coupling of two sequential bendable components. Overall, the proposed actuation module and kinematic model showed the ability of universal manipulation and an average tip position and direction RMSE of 0.65 mm and 0.23 degrees in free space.

Accurate clip positioning (including position, direction, and orientation) in transcatheter mitral edge-to-edge repair (M-TEER) is challenging due to the complexity of manipulating tendon-driven concentric catheters under imaging guidance. Existing methods are limited to either task-space position/shape control or image-space joint control. This study presents a compact eight-DoF robot for controlling the PASCAL device, achieving closed-loop pose control in image space. Building on a prior variable curvature model, we develop a kinematic model that accounts for coupling between catheter handles and compensates for tip length variation. A prior sheath shape model is also integrated to support safer navigation in confined anatomy during clip adjustment. To achieve precise image-space pose control, we design a novel framework featuring a mapping strategy for independent control of clip position, direction, and orientation relative to registered imaging views, along with a Jacobian-based PID controller. Simulation results demonstrate effective independent control, with only direction adjustments exhibiting minor coupling with orientation (maximum deviation: 2.69$^{\circ }$). Experiments show that closed-loop control effectively mitigates catheter misalignment and rubber deformation, achieving average positional and angular RMSEs to 0.52 mm and 0.61$^{\circ }$. This robot provides precise, image-space pose control, which is expected to assist with the challenge of accurate clip positioning in M-TEER.

Cardiac ablation (CA) is an interventional electrophysiological procedure used to disrupt arrhythmic substrates in the myocardium by inducing localized scarring. Current CA training relies on the master–apprentice model. In different fields of medicine including CA, virtual and physical simulators have proven to enhance, and even outperform, conventional training modalities while providing a risk-free learning environment. Despite the benefits, high costs and operational difficulties limit the widespread use of interventional simulators. Our previous research introduced a low-cost CA simulator using a 3D-printed biatrial cardiac model, successfully recording ten ablation lesions on the phantom myocardium. In this work, we present and evaluate an enhanced version: compared to the previous version, the cardiac phantom’s electrical behavior and ablation settings were optimized to produce consistent lesions, while 3D-printed components improved the haptic and radiographic properties of the simulator. Seven cardiologists compared the experimental simulator’s performance to the leading commercial system from Heartroid in a 24-question survey on a 5-point Likert scale. The four following areas of fidelity were considered: catheter entry, anatomical correctness, radiographic appearance, and mapping and ablation. The experimental simulator significantly outperformed the commercial system (p < 0.01), particularly in radiographic appearance (p < 0.01). The results show the potential for the experimental simulator in routine CA training.

Radiofrequency ablation (RFA) is a treatment used in the management of various arrhythmias including atrial fibrillation. Enhanced training for electrophysiologists through the use of physical simulators has a significant role in improving patient outcomes. The requirements for a high-fidelity simulator for cardiac RFA are challenging and not fully met by any research or commercial simulator at present. In this study, we have produced and evaluated a 3D-printed, bi-atrial model contained in a custom-made enclosure for RFA simulation using a new soft tissue-mimicking polymer, Layfomm-40, combined with thermochromic pigment and barium sulphate in an acrylic paint carrier. We evaluated the conductive properties of Layfomm-40, its sensitivity to RFA, and its visibility in X-ray imaging, and carried a full simulation of RFA in the cardiac catheterization laboratory by an electrophysiologist. We demonstrated that a patient-specific 3D-printed Layfomm-40 bi-atrial model coated with a custom thermochromic/barium sulphate paint was compatible with the CARTO3 electroanatomic mapping system and could be effectively imaged using X-ray fluoroscopy. We demonstrated the effective delivery and visualization of radiofrequency ablation lesions in this model. The simulator meets nearly all the requirements for high-fidelity physical simulation of RFA. The use of such simulators is likely to have impact on the training of electrophysiologists and the evaluation of novel RFA devices.

Objective: This study aimed to develop and evaluate a 3-degree-of-freedom (DoF) robotic system for the safe delivery of cardiac sheaths through challenging anatomical structures, including the fossa ovalis and pathways with tight curves. Methods: The robot and its kinematic model were built on a previously proposed single-DoF actuation module and bending model. A sheath delivery strategy (SDS) was developed, combining two control methods: tip position control to approach an optimal entry point and point-constrained control to maintain consistent navigation through this point, minimizing tissue contact. Technical performance was evaluated through trajectory-following and point-crossing tests, followed by feasibility experiments in a simulated scenario. Trials were conducted by three cardiologists using a validated phantom model under fluoroscopic guidance, comparing SDS with joint control (JC) and manual control (MC). Results: Average root mean square errors were 2.10 mm for tip position control and 1.86 mm for point-constrained control. SDS outperformed MC with significantly shorter trajectory lengths and lower root mean square jerk. Compared to JC, SDS reduced sheath-induced movements (an indirect measure of force) and increased retraction success rates at the fossa ovalis. Conclusion: The proposed robotic system reduced tissue wall contact compared to JC and provided smoother, more controlled operations than MC, ensuring safer and more effective delivery through confined pathways. Significance: This work contributes to advancing robotic-assisted cardiac sheath delivery, providing a reliable and safer method for navigating challenging anatomical structures.

In the growing field of electrophysiology, cardiac ablation either via heating or freezing target tissues using catheters, induces localised scarring to block or destroy defective electrical pathways in the heart. To test equipment and ablation settings, studies have resorted to ex-vivo and in-vivo models including pigs, dogs, and chickens. The use of animal tissue presents ethical and logistical complications and introduces variability between samples and between studies. In a scientific community faced with progressively more stringent ethics and regulations on animal testing, a more practical and ethical alternative should be established. To meet this need, multiple studies have proposed tissue-mimicking materials. However, either toxicity or poorly matched physical properties, prevented these materials from reaching widespread application. Furthermore, no material has yet been identified to test both cryoablation and radiofrequency ablation. Here, we present a novel thermochromic alginate hydrogel material that can simulate ablation lesions for both radiofrequency ablation and cryoablation. This material could find direct applications in electrophysiology, but adapted mixtures could also be used to recreate other tissues for different simulations.