Simulating Living Heart Valves in Abaqus

This blog highlights part of the PhD work of our colleague Elmer, conducted at Eindhoven University of Technology, where simulation met mechanobiology to explore one of the most ambitious applications of engineering tools: living heart valve replacements. 

Heart valve disease often requires surgical intervention. While current prosthetic valves can restore blood flow, they are non-living and cannot grow or adapt, posing a major limitation, especially for younger patients. This challenge is driving efforts to develop living valve replacements through tissue engineering or surgical techniques like the Ross procedure. These solutions require valves that can withstand physiological forces and biologically adapt over time, something conventional simulation methods struggle to predict. 

By leveraging user-defined material models (UMATs) in Abaqus, researchers are now able to simulate not just the mechanical behavior of these valves, but their growth and remodeling as living systems. 

Why Living Valves Need Simulation 

Our hearts contain four valves that ensure blood flows in the correct direction. Some of these, like the aortic and pulmonary valves, are subject to intense mechanical loads. When diseased, they often require replacement. But traditional valve prosthetics, while lifesaving, come with major limitations: they wear down, can cause immune responses, and most critically, do not grow with the patient. 

Two approaches aim to overcome this: 

• The Ross procedure, where a healthy valve from the patient’s pulmonary circuit is transplanted into the high-pressure aortic position. 

• Tissue-engineered valves, where biodegradable scaffolds are implanted and populated with the patient’s own cells. 

Both solutions depend on how the living tissue responds to new mechanical conditions, a question that can now be answered using simulation. 

Simulating Growth Using a UMAT in Abaqus 

To capture this complexity, a user-defined material model (UMAT) was developed in Abaqus to represent both heart valve tissue and the biodegradable scaffold. These materials are highly anisotropic and strain-stiffening, making their simulation non-trivial. 

Simulation of strain distribution in a living heart valve model using a UMAT in Abaqus

What made this UMAT unique was its ability to go beyond static material behavior: it simulated how the valve tissue grows and remodels over time, driven by local mechanical stimuli. Grounded in mechanobiology, the model connected mechanical stress to biological outcomes: 

• An increase in tissue mass led to local volume growth in the finite element mesh. 

• Changes in tissue composition directly affected local stiffness. 

This approach allowed researchers to virtually predict changes in geometry, mechanical function, and failure risk, without invasive procedures or trial-and-error experiments. 

Modeling Adaptation in the Ross Procedure 

The Ross procedure moves a pulmonary valve, used to operating under low pressure, into the high-pressure aortic position. This abrupt mechanical shift causes increased stress in the valve leaflets, which in turn stimulates tissue production and remodeling. 

By simulating this scenario in Abaqus, the model predicted local thickening and stiffening of the valve tissue, findings that closely matched observations in explanted Ross valves. Beyond validation, the model also enabled exploration of biological variability: valves with more mechano-sensitive cells adapted well, while less responsive ones showed signs of dilation and dysfunction. 

Visualization of mechanical stress adaptation in Ross procedure simulations

These insights suggest that patient-specific differences in biological responsiveness may explain why some Ross valves fail while others thrive, an important step toward personalized surgical planning. 

Designing Better Engineered Valves Through Simulation 

Tissue-engineered valves are designed to be implanted and then remodeled by the patient’s own body. In many cases, a preliminary valve is grown in the lab, decellularized to prevent immune reaction, and later repopulated by host cells. 

The culturing phase in the lab plays a key role in determining long-term success. But optimizing this phase experimentally is slow and expensive. That’s why the UMAT was further extended to simulate both in-vitro culturing and in-vivo adaptation. 

This enabled researchers to virtually test how different lab stimulation protocols (e.g. flow rate, stretch cycles, biochemical cues) influence cell behavior and mechanical outcome after implantation. Early results show that small adjustments during the lab phase can significantly affect tissue formation and durability in the body, providing a powerful tool for design optimization. 

Extending Abaqus Into Life Sciences 

This research shows how Abaqus can simulate much more than metal fatigue or crashworthiness. By integrating mechanobiology into custom material models, engineers and scientists can model growth, adaptation, and failure in living tissues, opening doors to simulation-driven innovation in the life sciences and medical device design. 

Dynamic simulation of valve growth and remodeling in response to mechanical stimuli

Interested in Using Abaqus for Biological Growth Simulation or Valve Modeling?

Reach out via our contact form or email us at sales@4realsim.com to discover how 4RealSim can help bring advanced life sciences simulation into your research workflow.