Heart Valve Testing Apparatus with Non-Sinusoidal Pressure Control
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Solution Overview
Problem
Current methods for testing prosthetic heart valves face challenges in replicating the high cycle rates and fluid dynamics required by standards like ISO 5840, particularly for flexible valves, leading to premature failure and false testing results due to excess reverse pressure spikes.
Innovation Solution
The development of a heart valve testing apparatus featuring a non-sinusoidal motion driven by a fluid impeller with a controllable actuator and pressure control system, including a bypass and compliance devices, to manage reverse pressures and ensure reliable testing protocols.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high cycle rate (1200 cycles per minute or more) is used to achieve 200 million cycles in reasonable time, then productivity is improved, but reverse pressure spikes occur causing false testing failures
Solution Approach 1:
The system dynamically adjusts the reverse pressure level during testing based on real-time valve position detection. When the valve is detected to be in an unstable position (prone to spiking), the reverse pressure is automatically reduced to prevent false failures, while allowing higher pressure when the valve is stable. This dynamic adaptation enables high-speed testing without sacrificing accuracy.
Solution Approach 2:
The system employs feedback mechanisms by continuously monitoring valve position and stability during the testing cycle. This feedback information is used to adjust reverse pressure levels in real-time, creating a closed-loop control system that prevents pressure spikes while maintaining high testing speed. The feedback ensures that productivity gains do not compromise testing reliability.
2Measurement precision
If excess reverse pressure is applied to achieve thorough testing, then measurement precision is improved, but heart valves fail prematurely causing false testing failures
Solution Approach 1:
The system dynamically modulates reverse pressure based on detected valve stability. When valves are detected to be in unstable positions where spiking is likely, the reverse pressure is automatically reduced to prevent premature failure. When valves are stable, full testing pressure is applied. This dynamic approach maintains measurement precision while protecting valve durability.
Solution Approach 2:
The system takes preliminary anti-action by detecting potentially unstable valve positions before excess pressure is applied. By identifying valves at risk of spiking in advance, the system can pre-adjust pressure levels to prevent false failures, thereby maintaining thoroughness without compromising durability.
3Productivity
If flexible animal tissue valves are tested at high cycle rates, then productivity is improved, but fluid dynamic effects cause difficulty in complying with testing standards
Solution Approach 1:
The system uses feedback from valve position detection to automatically adjust testing parameters in real-time. This feedback mechanism simplifies compliance with testing standards by eliminating the need for manual intervention, even when testing flexible animal tissue valves at high speeds. The automated adjustments handle fluid dynamic effects without increasing operational complexity.
Solution Approach 2:
The testing system performs self-adjustment based on detected valve characteristics and stability. Rather than requiring complex external control for each flexible valve type, the system autonomously adapts its parameters to comply with standards, thereby maintaining high productivity without proportionally increasing device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution allows for accurate and reliable testing of heart valves by controlling reverse pressures and minimizing peak pressures, reducing the risk of premature failure and false negatives, while enabling enhanced long-term reliability assessment.
Implementation Method 1
a fluid impeller such as a bellows or piston that is reciprocated in a non-sinusoidal trajectory
Implementation Method 2
a bypass and a controllable bypass valve that is controlled to limit reverse pressures applied to a heart valve under test
Implementation Method 3
a pressure control system comprising compliance devices upstream and/or downstream of a heart valve under test
Data Source
AI summary
Methods and apparatus for accelerated wear testing of prosthetic heart valves apply non-sinusoidal pressure waveforms. The waveforms may maintain a threshold reverse pressure for a desired duration while limiting a peak reverse pressure. Apparatus may include a fluid impeller such as a bellows or a piston driven by an actuator having a position controlled by a motion control system. The apparatus may include a pressure control system comprising one or more bypass channels and bypass valves controlling a resistance of the bypass channels to fluid flow. The bypass valves may be controlled in real time.