Measuring Stress on a Third-Generation Balloon-Expandable Aortic Valve During Expansion

Area of Science:

• Biomedical Engineering
• Cardiovascular Research
• Materials Science

Background:

• Transcatheter aortic valve replacement (TAVR) is a key treatment for aortic stenosis.
• Third-generation balloon-expandable valves like the Edwards SAPIEN 3 (S3-TAV) are widely used.
• Aortic calcification poses challenges to TAVR device performance and longevity.

Purpose of the Study:

• To determine mechanical stresses on the S3-TAV during crimping and expansion in the presence of aortic calcification.
• To identify critical regions of stress concentration within the valve.
• To correlate simulated stress patterns with potential clinical complications like thrombosis and degeneration.

Main Methods:

• Reconstruction of a 3D computer-aided design (CAD) model of the S3-TAV.
• Finite element analysis (FEA) simulations of valve crimping, reopening, and systemic pressure loading.
• Utilized high-resolution micro-computed tomography scans for accurate geometric meshing.
• Material properties derived from surgical bioprostheses and cobalt-chromium alloys.

Main Results:

• Peak stresses during crimping were concentrated at the commissural tips, the leaflet attachment sites.
• These stress hotspots are identified as potential sites for thrombosis and valve degeneration.
• Persistent bulky calcifications post-expansion can lead to paravalvular leakages (PVLs), precursors to thrombosis and degeneration.

Conclusions:

• The crimping process induces significant stress at the commissural tips of the S3-TAV.
• Aortic calcification is a critical factor influencing valve stress distribution and potential failure modes.
• Understanding these mechanical stresses is crucial for improving TAVR device design and patient outcomes.