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Catheter-based intervention procedures contain complex maneuvers, and they are often performed using fluoroscopic guidance assisted by 2D and 3D echocardiography viewed on a flat screen that inherently limits depth perception. Emerging mixed reality (MR) technologies, combined with advanced rendering techniques, offer potential enhancement in depth perception and navigational support. The study aims to evaluate a MR-based guidance system for the atrial septal puncture (ASP) procedure utilizing a phantom anatomical model. A novel MR-based guidance system using a modified Monte Carlo-based rendering approach for 3D echocardiographic visualization was introduced and evaluated against standard clinical 3D echocardiographic display on a flat screen. The objective was to guide the ASP procedure by facilitating catheter placement and puncture across four specific atrial septum quadrants. To assess the system's feasibility and performance, a user study involving four experienced interventional cardiologists was conducted using a phantom model. Results show that participants accurately punctured the designated quadrant in 14 out of 16 punctures using MR and 15 out of 16 punctures using the flat screen of the ultrasound machine. The geometric mean puncture time for MR was 31 s and 26 s for flat screen guidance. User experience ratings indicated MR-based guidance to be easier to navigate and locate tents of the atrial septum. The study demonstrates the feasibility of MR-guided atrial septal puncture. User experience data, particularly with respect to navigation, imply potential benefits for more complex procedures and educational purposes. The observed performance difference suggests an associated learning curve for optimal MR utilization.

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BACKGROUND: Echocardiography is a highly specialised examination performed by experienced healthcare professionals. These experienced healthcare professionals may not be available to patients during all hours in rural healthcare facilities. Remote-guided echocardiography could improve the availability of specialised care for patients living in rural areas. This study examined the feasibility of real-time remote guidance for medical students to perform an echocardiographic assessment of the left side of the heart. Thirteen healthy volunteers were recruited for remote-guided echocardiography, which was performed by 13 medical students. Student examinations/images were compared to reference echocardiography. Measurements of left ventricular fractional shortening and mitral valve blood flow velocity were also compared. Furthermore, guidance through a smartphone videoconference was compared to designated remote guidance software. RESULTS: Two-thirds of the images acquired by students were rated as medium or good quality and usable to evaluate two thirds of the cardiac structures. No significant bias was found for left ventricular fractional shortening. The measurements from the students' exams had a variation coefficient of 14.8% compared to the reference. The calculated deviation of the insonation angle was above 25° for both E and A-wave mitral valve blood flow velocity measurements. Images acquired by guidance through smartphone videoconference were of lower quality than those obtained using the designated remote guidance software. CONCLUSION: Real-time remote-guided echocardiography performed by medical students has limited value for clinical screening but could be useful for educational purposes.

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OBJECTIVES: This population-based, comprehensive, retrospective study presented the clinical outcomes of all children born in Norway between 2003 and 2017 with double outlet right ventricle (DORV). METHODS: All children born with DORV between 2003 and 2017 were identified in the Oslo University Hospital registry. Patients' characteristics, interventions, complications and deaths were recorded. Echocardiographic data were reviewed for classification according to current standards. We investigated time-dependent surgical reintervention and mortality using Kaplan-Meier analyses and determinants of treatment complications, reintervention and death using regression analyses. RESULTS: Ninety-three children with DORV represented an annual median prevalence of 1.18 per 10 000 births in Norway. Six children received palliative care. With an intention to treat, a surgical route with the primary biventricular repair was followed for 62 children, staged biventricular repair for 15 and univentricular repair for 10 children. Major complications occurred in 1.0% and 6.2% of children following catheter or surgical intervention, respectively. No significant determinants of the complications were identified. Overall survival following treatment was 91.9%, 90.8%, 89.5% and 89.5% and corresponding freedom from surgical reintervention was 88.0%, 79.0%, 74.9% and 69.4% at 1, 2, 5 and 10 years, respectively. The presence of atrioventricular septal defect predicted an increased risk of mortality (hazard ratio: 7.16) but did not increase the risk of surgical reintervention. CONCLUSIONS: In Norway, most children receive tailored treatment for DORV with low rates of complications, surgical reinterventions and mortality. However, atrioventricular septal defect remains a potential determinant of postoperative death.

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OBJECTIVE: To assess the influence of stent application on in-stent hemodynamics under standardized conditions. METHODS: Ovine common carotid arteries before and after stent (6 × 40 mm, sinus-Carotid-RXt, combined open-closed cell design; Optimed, Ettlingen, Germany) application were used. Plastic tubes, 10 mm in length, simulating stenosis were placed in the middle of the applied stent to induce different degrees of stenosis (moderate 57.8% and severe 76.4%). Flow velocity and dynamic compliance were, respectively, measured with ultrasound and laser scan; proximal, in-stent, and distal to the stented arterial segment (1 cm proximal and distal) in a pulsatile ex vivo circulation system. RESULTS: Stent insertion caused the in-stent peak systolic velocity to increase 22% without stenosis, 31% with moderate stenosis, and 23% with severe stenosis. Stent insertion without stenosis caused no significant increase in in-stent end-diastolic velocity (EDV) but a 17% increase with moderate stenosis. In severe stenosis, EDV was increased 56% proximal to the stenosis. Compliance was reduced threefold in the middle of the stented arterial segment where flow velocity was significantly increased. CONCLUSIONS: With or without stenosis, stent introduction caused the in-stent peak systolic velocity to become significantly elevated compared with a nonstented area. EDV was also increased by stent insertion in the case of moderate stenosis. The stent-induced compliance reduction may be causal for the increase in flow velocity since the stent-induced flow velocity elevation appeared in the stented area with low compliance. Because of altered hemodynamics caused by stent introduction when measured by duplex ultrasound, caution is prudent in concluding that carotid artery stenting is associated with a higher restenosis rate than carotid endarterectomy. Mistakenly upgrading moderate to severe restenosis could result in unnecessary reintervention. CLINICAL RELEVANCE: Clinical experience and prior studies support the supposition that restenosis after carotid artery stenting in carotid lesions displays erroneously elevated velocity when evaluated by duplex ultrasound (DUS), thus contributing to misleading interpretation of the degree of stenosis. This study, in contrast to studies of other groups, employs exactly the same conditions to measure flow with DUS in an unstented and then stented section of the carotid artery. Since DUS is the first-choice tool for carotid artery evaluation, knowledge about inexactness of the method is essential to avoid errors in treatment or follow-up decisions.

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