Full MODSIM Process for Stent Deployment

Enhance real world medical practice through full MODSIM virtual experience for stent deployment.

An article by Iris Blume , Dima Likhachev, PHD, MBA and Nicolas Ladislas Sénémaud

Introduction 

At Dassault Systèmes, our daily mission is to collectively make a profound impact on the world. We are a community of innovators, dreamers, and doers who transform concepts into realities, tackling some of the world's most pressing challenges while serving our valued clients, partners, and the communities that surround us.

In this context, we delve into the vital realm of cardiovascular device development, where innovation can truly save lives. Today, we explore the critical role of stents in addressing cardiovascular diseases (CVDs), unveiling how advanced modeling and simulation methods can reshape the landscape of patient care. We also shed light on the challenges faced during their development and regulatory approval process.

CVDs, which affect the heart, arteries, and veins throughout the body, stand as the leading global cause of mortality, accounting for an estimated 32% of all deaths annually (World Health Organization, 2021). CVDs continue to afflict a growing number of individuals, making stents one of the most commonly utilized medical devices. A stent, typically composed of Nitinol, acts as a steel spring inserted into an artery to regulate blood flow, addressing a wide range of cardiovascular ailments, from cholesterol blockages to aneurysms.

Challenges

In the realm of medical practice, predicting the behavior of a stent post-insertion into a patient's anatomy holds paramount importance for ensuring treatment efficacy. Physicians and surgeons often rely on empirical assessments, scrutinizing MRI scans to determine the appropriate stent and insertion technique. However, this approach poses inherent risks, especially in complex cases like cerebral aneurysms. It is evident that this process could benefit from refinement and acceleration through the utilization of advanced modeling and simulation methods.

While stent manufacturers have already embraced simulations to assist physicians in their pre-operative evaluations, these simulations tend to be exceedingly time-consuming. Existing methods, though highly precise, predominantly rely on simulation tools such as Abaqus. The process involves multiple data preparation steps, resulting in a staggering timeframe of approximately 18 hours to complete a single stent structural simulation, with some cases taking up to 48 hours to deliver the simulation results.

Solution 

In our pursuit of more efficient cardiovascular device development, we propose a practical solution. By employing MODSIM methods, particularly in optimizing data preparation, we aim to cut simulation time in half. This approach utilizes generative design to automatically generate precise models for stents and patient anatomy, streamlining the inputs for :

• Finite Element Analysis (FEA) for the stent structural simulation and;
• Computational Fluid Dynamics (CFD) for the blood flow simulation

We are introducing a new 100% cloud-based MODSIM approach on the 3DEXPERIENCE Platform that covers all aspects of stent deployment analysis. Our primary goal is to reduce the risks associated with device development, ensuring that issues such as fracture, migration, or failure to meet functional requirements become less common. This innovation reflects our ongoing commitment to improving healthcare and related fields.

• generative design:to accurately model the stent and have full control over its geometry through parameters and design rulesto reverse engineer the specific patient anatomy automatically generating the artery centerline
• to structural simulation:to simulate its structural behaviors while deploying into the arteryto simulate deformation of the stent in the blood flow 
• to fluid simulation:to simulate influence of stent on the blood flowto simulate a particles flow and stagnation points

In our scenario, 6 steps all chained together will take us though a complete stent deployment analysis:

1. Parametric stent design
2. Patient anatomy reverse engineering
3. Stent calibration and positioning
4. Stent deployment
5. Blood flow simulation
6. Results interpretation

Digital continuity between those steps accelerates tremendously the overall process making it automatable regardless of the anatomy complexity. It will allow us to provide a complete analysis of the stent deployment in specific patient anatomy answering crucial questions:

• Wall apposition on the sealing zones > Does the stent fit properly the anatomy?
• Stent displacement with blood stream  > Does the stent stay fixed with time?
• Particle accumulation > Is there a particle accumulation because of beaks on the sealing zones?
• Blood flow limitation in aneurysm > Does the aneurysm reduce size after stent insertion?

Process 

In this video, the team explains the end to end process, going over the 6 steps mentioned above.

Results interpretation

This end-to-end continuous process will therefore cover all aspects of stent modelling to its impact on the blood flow once inserted. Much faster than conventional method, it is delivered in one single process without interoperability issues for the first time. We summarize the design and setup time of the full MODSIM process for stent deployment in the table below:

Conclusion 

Process time has been drastically reduced (18h to 4h for the FEA part) thanks to innovative and simpler methodology. MODSIM approach allowed to automatically generate accurate informed geometries ready to be used for simulation. Chainging Design <> FEA <> CFD in one single process wouldn't have been possible without using generative design technologies on the 3DEXPERIENCE platform insuring strong and consistent interfaces between all the steps. 

Those comparisons show on one hand the impact of the stent on the blood stream, reducing pressure and flow in the aneurysm, but also validates its position in the artery maximizing wall apposition. Therefore this workflow answers the most critical pre operational unknowns such as how the stent will deploy (wall apposition), how will it affect the blood stream and will it limit the blood flow in the aneurysm with time. Delivering those answers, using a standardized and automatic process, increases the value and access of technology to surgeons, stent manufacturers, opening the door to large scale studies on patient cohorts. This virtual experience will definitely secure complex real world surgical operations to provide tailor made solutions.

Special thanks to Jean Sénémaud for his precious guidance