Immersive training in cardiology : focus on coronary obstructions surgery process with virtual reality

Chapter 1. State of Art 1.4. VR applications in cardiology

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Conclusion

Interventional cardiology is a demanding medical discipline requiring precise technical skills and real-time decision-making. Traditional training methods, while effective, often face challenges of cost, access, and standardization, particularly in low and middle income countries. In this context, virtual reality emerges as a valuable complementary tool for training healthcare professionals. It enables learners to visualize complex procedures in a risk-free, immersive environment particularly those involving the treatment of coronary obstructions, which require high precision and confidence. By simulating real-life coronary interventions, VR fosters deeper understanding, improves procedural memory, and enhances practitioner readiness before clinical exposure. This approach can significantly contribute to the democratization of specialized medical education by making high-quality, targeted training such as for coronary obstruction treatment more accessible, flexible, and context-relevant. The observations and gaps identified in this chapter provide a solid foundation for proposing a VR-based training solution tailored to the specific needs of interventional cardiology.

The following chapter will present our solution through its design and the various tools used to implement it.

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Chapter2

Conception and technical choices

Introduction

At the beginning of creating an application, it is necessary to formalize the preliminary steps of its development to make it more aligned with the client's needs. This chapter presents the various phases of modeling the proposed solution as well as the different tools and technologies used for its implementation.

2.1 Analysis and design

This phase consists of understanding the context of the application. It involves determining the functionalities and performance criteria that our application must fulfil.

2.1.1 Needs analysis

Functional needs

Functional needs are the system's functionalities, they represent the user's primary needs. Thus, through the solution, the user will be able to:

· Select and view a healthy heart, an obstructed heart, and/or the operating room and equipments in 3D ;

· Simulate assisted PCI or CABG on an obstructed heart;

· Simulate autonomous PCI or CABG on an obstructed heart; Once we have designed an administrator system, the administrator will be able to:

· Add or modify training modules;

· Update 3D models or clinical cases;

Non-functional needs

Non-functional needs are those that characterize the system. These are needs relating to performance and hardware type. The non-functional needs of the solution can be listed as follows:

·

Chapter 2. Conception and technical choices 2.1. Analysis and design

Comfortable VR experience (minimal eye strain and motion sickness);

· Attractive and user-friendly interfaces;

· Realistic and intuitive interactions;

· Smooth and stable performance (high frame rates, low latency, fluid animations);

· Immersive and visually accurate environment;

· Ergonomics and hardware compatibility;

2.1.2 Design

2.1.2.1 Technical design

We now enter the modelling phase. It is an essential part of large software projects and is also useful for medium-sized and even small projects. For this phase, we have opted for the UML (Unified Modeling Language) modelling language which is [39] is a standard modeling language that uses diagrams to help developers design, understand, and document software systems and business processes. In the following sections, we reprensent our system with both a use case diagram and a sequence diagram.

Use case diagram

The use case diagram in Figure 2.1 shows the different actions performed by the actors. An actor represents a person, process, or object outside the system that interacts with it.

Figure 2.1: Use case diagram

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Chapter 2. Conception and technical choices 2.1. Analysis and design

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Sequence diagram

The sequence diagram shows the interactions between the system and the actors in chronological order. Figure 2.2 shows the sequence diagram for the use case `Simulate surgery on an obstructed heart'.

Figure 2.2: Sequence diagram for the use case "Simulate surgery on an obstructed heart"

2.1.3 Fundamental design

The different stages of our application's development are:

· Project analysis: Understanding the needs, defining learning objectives, features, and target users.

· 3D object modeling: Creating digital models of organs, coronary vessels, medical tools, and the surgical environment.

· Model animation: Adding realistic movements (catheter insertion, heartbeat, blood flow) to simulate medical procedures.

· Immersive environment assembly: Integrating the models into a fully interactive and realistic VR scene.

·

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User Interface development: Designing menus, controls, and feedback systems to guide the user through the simulation.

· Visual identity design: Creating the logo, selecting colors and fonts to ensure a consistent visual branding.

· Demo testing: Conducting initial testing to evaluate usability, flow, and relevance of the content.

· Project compilation and testing: Final technical adjustments, debugging, and optimization for deployment.

· Performance tracking integration: Adding a system to monitor user progress, scores, and provide feedback for learning.

2.2 Technical choices

Several technical resources were mobilised to develop the virtual reality simulation application. These can be divided into two main categories: on the one hand, tools dedicated to designing the 3D universe, such as modelling and texturing software; on the other hand, those essential to the functioning of the simulation, including a game engine, a programming language and an SDK adapted to virtual reality.

2.2.1 Choice of 3D modelling and animation software Blender

Blender is a free and open-source software for 3D modeling, animation, rendering, compositing, and video editing. Highly versatile and powerful, it is widely used across fields such as visual effects, game development, architecture, and virtual reality. It enables the creation of realistic or stylized 3D scenes, texturing, lighting, object and character animation, as well as simulation of physical phenomena like smoke, fluids, and collisions. As a cost-free solution, it stands as a strong alternative to expensive professional software. [40]

Originally developed by the Dutch animation studio NeoGeo in the 1990s, Blender was released to the public in 1998. After the bankruptcy of NaN (Not a Number), the company that distributed Blender, the open-source community rallied to buy back the software and continue its development under a free license. Since then, Blender has been actively maintained by the Blender Foundation and a large global community of developers and artists. Today, it is recognized as a professional-grade tool used by both indie creators and major studios. [41]

In our surgical simulation application, Blender was used to create realistic 3D models of the human heart and simulate surgical interactions for treating coronary obstructions. Its sculpting, rigging, and animation tools allowed precise modeling, procedure animation, and immersive visual integration. While alternatives like Autodesk Maya, 3ds Max, Cinema 4D, and ZBrush exist, Blender was chosen for its free access, active community, frequent updates, and seamless compatibility with Unity, making it ideal for efficiently producing realistic biomedical models.

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Figure 2.3: Operating room design in Blender 2.2.2 Choice of game engine and programming language

Unity & C-Sharp (C#)

Unity, developed by Unity Technologies, is a widely used cross-platform engine for creating interactive 2D and 3D applications, including VR and AR simulations. Its robust tools for rendering, physics, scripting, and asset management, along with multi-platform deployment, made it ideal for our project. We used Unity 2020.3.41f1 (LTS) for stability and long-term support, leveraging C#, Unity's native language, which offers clean object-oriented syntax, automatic memory management, and seamless integration with Unity's API. This enabled us to efficiently implement VR interactions, simulate surgical procedures, design user interfaces, and maintain a structured, maintainable code-base. The engine also allowed seamless integration with 3D assets created in Blender and facilitated real-time testing of surgical scenarios. Compared to alternatives like Unreal Engine (C++) and Godot (GDScript), Unity provided the best combination of flexibility, performance, and mature VR support, ensuring a smooth development process for our immersive cardiology training software.

Figure 2.4: Using the Unity3D engine to create the VR experience

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2.2.3 IDE

To write, debug, and manage our C# scripts within Unity, we used Visual Studio Community 2017. This free, full-featured IDE developed by Microsoft is officially supported by Unity and offers excellent integration with it, including IntelliSense, debugging tools, error tracking, and project organization. Its lightweight setup and reliable performance made it an ideal choice for our workflow, especially in the context of Unity 2020.3.41f1.

Other alternatives like JetBrains Rider, Visual Studio Code, or MonoDevelop exist, but Visual Studio Community stands out due to its deep Unity support, professional-grade features, and longstanding stability. Its compatibility with Unity packages and ease of configuration for VR scripting made it especially valuable during our project.

Figure 2.5: Script for animating the user's hands written in Visual Studio 2017 2.2.4 Choice of SDK and frameworks for YR

· SDK

The Software Development Kit we used is Oculus XR Plugin[43], a comprehensive set of tools, libraries, and resources provided by Unity for developers who want to create virtual reality (VR) experiences for Oculus headsets, including Quest, Quest 2, Quest 3, and Rift devices. It offers robust support for device tracking, controller input, hand tracking, haptic feedback, and platform-specific optimizations, making it easier to build immersive and responsive VR environments. Although primarily designed for Oculus hardware, it can be combined with Unity's XR framework to support cross-platform VR development. The choice of the Oculus XR Plugin in our project is due to its native compatibility with Oculus devices, ensuring precise interactions and smooth locomotion. It also excels in delivering an intuitive and immersive user experience, which was essential for our VR application.

· Frameworks

We used the Unity XR Interaction Toolkit, a flexible framework designed to simplify the creation of VR and AR experiences by providing ready-to-use components for interactions, locomotion, and user interface control [42]. It allows developers to define interactive objects (which users can grab, tap, or manipulate) and interactors, which represent input devices such as VR

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controllers or hand tracking. In the context of our project, this toolkit proved essential for enabling intuitive manipulation of surgical tools.

2.2.5 Others softwares Adobe Illustrator

Adobe Illustrator is a widely recognized vector graphics creation software in professional environments. Part of the Adobe suite, it can be used independently or in conjunction with Photoshop, offering powerful vector drawing tools. Vector images, composed of curves defined by mathematical formulas, have the advantage of being resolution-independent, meaning they retain their quality even when enlarged. Illustrator is suitable for creating printed documents as well as illustrations for the web, such as logos and posters. It offers numerous features designed to enhance productivity. For creating the logo of our application, we chose to use Adobe Illustrator CC 2020. Figure 2.6 shows the software interface during its use for designing the logo.

Figure 2.6: Adobe Illustrator interface screenshot

Adobe Photoshop

Adobe Photoshop is a computer-assisted editing, processing, and drawing software, introduced in 1990 and available for MacOS and Windows since 1992. Developed by Adobe, it is primarily used for digital photo processing and also allows for creating images from scratch. Photoshop mainly works with raster images, which are composed of a grid of points called pixels. The advantage of these images is their ability to reproduce subtle color gradations.

2.3 Development methodology

The software was developed using an Iterative and Incremental Development approach, enabling gradual building, testing, and refinement. This methodology is especially suitable for projects involving 3D modeling, VR integration, and interactive software. The main stages of development are

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outlined below:

· Specification definition: The project started by defining application requirements and objectives, detailing expected features, user interactions, and the scope of simulated surgical procedures. This stage provided a solid foundation for all subsequent development activities.

· Project planning and task breakdown: The project was divided into smaller, manageable tasks, each producing deliverables that contributed to the overall application. This approach enabled effective progress tracking, task prioritization, and iterative improvements.

· Information gathering: Medical accuracy was ensured by collecting information from online sources, cardiology students, and professional cardiologists. This research informed the VR representation of operating procedures and surgical workflows.

· Scenario and workflow development: Application scenarios and surgical procedure scripts were created to define user interactions, procedural sequences, and expected behaviors within the virtual environment.

· Modeling and asset creation

- Installation and setup of Blender and Adobe Photoshop - Modeling, texturing, and basic animation of 3D objects - Exporting 3D models for integration into Unity

· Integration and Incremental Development in Unity

- Design of the logo and graphic charter to ensure visual consistency;

- User interface (UI) design and layout;

- Installation of Unity and required SDKs;

- Importation of characters and 3D models;

- Creation of different scenes and VR camera configuration;

- Learning and applying C# to implement interactive features;

- Writing scripts to manage events and functionalities;

- Development of incremental features and functionalities;

- Deployment on the Oculus Quest 3 headset for iterative testing;

· Testing, validation, and refinement: Each increment of the application was tested to ensure correct functionality, usability, and immersion. Feedback from testing guided adjustments and improvements, allowing the application to evolve gradually toward the final version.