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Introduction Low volume and high complex cardiac surgery such as resection of excess heart muscle (myectomy) has proven to be effective, yet, serious complications such as a ventricular septal defect, and complete heart block leading to pacemaker implantations may occur even for experienced surgeons. In situ simulation-based practice before actual surgery might improve patient outcomes. As simulation and clinical practice becomes more and more intertwined, we aimed to develop and implement three-dimensional (3D) heart models in preoperative planning and training to improve pre-operative patient-specific anatomy insights and surgical technique in an observational study to ultimately improve surgical outcome. Methods Eight consecutive patients scheduled for surgical myectomy received cardiac Magnetic Resonance Imaging (MRI) based 3D-planning from September 2020 to August 2022. The dedicated cardiac MRI examination resulted in a high resolution 3D sequence of the heart and thoracic blood vessels. Models increased in complexity over time from a) an in silico anatomical model, to b) 3D-printed septal myectomy planning, to c) pre-operative in situ surgical practice on a silicone model, and to d) intraoperative assessment of actual heart muscle resection compared to pre-operative planning. The models were also used for patient consultation and surgical informed consent. Our small sample size was deemed too small for quantitative analysis of patient outcomes. Results & Discussion An in silico 3D anatomical model of the heart with height map is visualised in Figure 1a. Thickened heart tissue exceeding 15 mm was printed in red for visual guidance of surgical resection (Figure 1b). In situ simulated resection of excess heart tissue was simulated on the silicone model one day before the actual surgery (Figure 1c), and allowed for adjustment of the planned resection. The pre-operative surgical plan and actual resected myocardial tissue volume and size were compared intraoperatively (Figure 1d). Since introduction of the patient-specific models, surgeons feel better prepared, more confident, and feel better supported making pre- and intra-operative decisions. Additionally, patients feel better informed about the actual procedure during outpatient consultation. In situ patient-specific simulation of complex cardiac surgery has become regular surgical practice in our hospital. It is recommended to implement and evaluate the presented workflow in other cardio-thoracic surgery centres, and for other disciplines to demonstrate improvement in patient outcomes. Keywords High Fidelity Simulation Training; Heart surgery; Three-Dimensional Imaging; Just-in-time simulation References/Acknowledgements Aggarwal R. Just-in-time simulation-based training. BMJ Quality & Safety 2017;26:866-868. https://dx.doi.org/10.1136/bmjqs-2017-007122 Ralph-Edwards A, Vanderlaan RD, Bajona P. Transaortic septal myectomy: techniques and pitfalls. Annals of Cardiothoracic Surgery 2017;6(4):410-415. https://doi.org/10.21037/acs.2017.07.08

With great interest we read the systematic review and meta-analysis by Osborne et al. on the effectiveness of high- and low-fidelity simulation-based medical education in teaching cardiac auscultation. We congratulate the authors for their efforts to provide a systematic review on simulation-based education. While the authors conclude that high-fidelity simulation has no benefit in improving cardiac auscultation knowledge or skills compared with low-fidelity simulation, we believe that this conclusion cannot be supported by the authors’ work.

Objectives: High-volume ECMO centers have better clinical outcomes than low-volume centers due to higher clinical exposure. Simulation-based training (SBT) can be an alternative for these centers to reach similar experience levels. SBT not only improves education of the individual caregiver but also improves multidisciplinary ECMO teams. However, ECMO simulators and/or simulations (Sims) differ on realism and functions, making each of these simulators useful for different purposes. Classifying Sims is often subjective and left to the individual user and/or creator. This scoping review aims to present a structured and objective way to classify available Sims. Methods: Physical and/or computational Sims with public information in English were screened for eligibility. Overall fidelity was established by taking the median of definition-based fidelity, derived from literature, and combining this with the median of our newly established component fidelity and customization fidelity. Component fidelity was based on the main elements of ECMO support while customization fidelity was based on main parameters to (re)create a unique patient, see table. Sims were subsequently classified as being low-, mid-, or high-fidelity. Results: Universal definitions for SBT were applied to Sims. According to our objective classification method, 10 (38%) low, 16 (62%) mid and no highfidelity Sims exist. Most (54%) Sims are lacking customization options for patient-specific modelling. Conclusions: Overall fidelity of available Sims were objectively classified based on definition-based, component, and customization fidelity. No high-fidelity Sims currently exists, urging for development of a high-fidelity simulator to improve ECMO-team training and improve patient outcomes. With our method, future Sims can be classified more objectively allowing for users and researchers to compare accordingly.

Untethered helical magnetic devices (UHMDs) have the potential to navigate bodily fluids using permanent-magnet robotic systems for minimally invasive diagnostic and surgical procedures. These devices can be actuated by robotically moving rotating permanent magnets (RPMs) to achieve controllable steering and propulsion simultaneously in a wireless manner. To date, the vast majority of motion control systems using UHMDs are constrained to operate in the absence of a dynamic flow field and prior work did not rigorously address the fundamental roles of rheological, magnetic, and geometric characteristics of the UHMD and its surroundings on the resulting stability. In this work, we show how to construct the region of attraction of a UHMD driven by two synchronized RPMs inside fluid-filled lumen around an equilibrium point. We first present the governing hydrodynamic model of a magnetically-driven UHMD to describe its behavior against the flow of blood serum. Then we validate the model using 1-D frequency response characterization and show that it captures the measured linear relationship between the actuation frequency and propulsive thrust at various flow fields. We find that a region of asymptotic stability can be achieved around an equilibrium point allowing a 6-mm-long UHMD to overcome maximum volumetric flow field of 1.2 l/hr (i.e., 2.65 cm/s).