Transcatheter Heart Valve Downstream Fluid Dynamics in an Accelerated Evaluation Environment

Area of Science:

• Biomedical Engineering
• Cardiovascular Research
• Medical Device Testing

Background:

• Transcatheter aortic valve replacements (TAVRs) offer minimally invasive treatment for aortic valve disease.
• Long-term durability of TAVR bioprosthetic heart valves (BHVs) requires further investigation.
• Current pre-clinical testing using accelerated wear testers (AWTs) lacks clear validation for predicting in vivo performance.

Purpose of the Study:

• To characterize the fluid dynamics within an ISO:5840 compliant AWT.
• To compare AWT conditions to in vivo or in vitro physiological loading relevant to TAVR BHVs.
• To assess the accuracy of AWTs in predicting TAVR BHV durability.

Main Methods:

• High-speed particle image velocimetry was used to quantify velocity fields, Reynolds stresses, and turbulence intensity in an AWT.
• TAVR enface imaging was employed to determine orifice area and estimate flow rate.
• Fluid dynamics and loading conditions were analyzed during simulated systole and diastole.

Main Results:

• Peak systole showed maximum central jet velocity (0.50 m/s), Reynolds stresses (265.1 Pa, 124.6 Pa), and turbulence intensity (37.3%).
• AWT recirculation during diastole created retrograde flow and eddies.
• The AWT demonstrated a reduced valve fully loaded period and pressure compared to in vivo/in vitro conditions, despite similar fluid environments and TAVR motion.

Conclusions:

• Current AWTs may not accurately replicate the in vivo loading conditions experienced by TAVR BHVs.
• The characterized fluid environment in the AWT suggests limitations in its ability to predict long-term TAVR durability.
• Further refinement of AWTs is necessary for reliable pre-clinical assessment of TAVR BHV performance.