A Novel Technique for Experimental Flow Visualization of Mechanical Valves

Area of Science:

• Biomedical Engineering
• Fluid Dynamics
• Cardiovascular Devices

Background:

• Thromboembolic events (TEs) are a significant risk associated with mechanical heart valves.
• The hinge region's geometry is suspected to influence the occurrence of TEs.

Purpose of the Study:

• To develop and validate a novel technique for visualizing washout dynamics in mechanical heart valve hinge areas.
• To assess differences in washout characteristics between two commercial mechanical heart valve designs.

Main Methods:

• A dairy-based colloidal suspension (DBCS) was employed as a high-contrast tracer.
• Valves were mounted in fluidic channels, and DBCS was introduced into hinge regions.
• Time-lapse imaging and image analysis were used to quantify washout rates and patterns.

Main Results:

• Increased flow rates led to improved washout and reduced clearance times.
• Significant differences in washout rate time constants were observed between valve types (>40% faster clearance in one type, p < 0.01).
• Topographic maps revealed unique washout patterns for each valve design, with high reproducibility (SEM ±3.9).

Conclusions:

• The developed visualization technique effectively characterizes washout in mechanical heart valve hinges.
• Distinct washout patterns suggest potential links between hinge geometry, flow dynamics, and TEs.
• This methodology can aid in identifying stagnation zones and evaluating designs to mitigate TE risks.