Cardiac Assist Flow Measurement With Doppler Ambiguity Correction
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Solution Overview
Problem
Existing methods for determining fluid flow velocity in implanted vascular support systems, such as left-heart support systems, face challenges due to the violation of the Nyquist sampling theorem caused by long signal transit times and high flow velocities, leading to ambiguities in pulsed Doppler measurements using a single ultrasound transducer.
Innovation Solution
A method that utilizes a pulsed Doppler measurement with a single ultrasound transducer, combined with operating parameters of the flow machine, to correct ambiguities in the measurement results by selecting the most plausible flow velocity or volume flow based on the motor characteristics, allowing precise determination of fluid flow even in conditions that violate the Nyquist sampling theorem.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pulsed Doppler measurement is performed with a single ultrasound transducer in implanted vascular support systems, then measurement precision is improved, but measurement ambiguities occur due to violation of Nyquist sampling theorem
Solution Approach 1:
The patent introduces operating parameters (rotational speed, differential pressure) as intermediary information to resolve ambiguities in the Doppler measurement. These parameters act as mediators between the ultrasound measurement system and the flow machine, allowing disambiguation of the flow velocity measurements without requiring additional ultrasound transducers or changing the fundamental measurement approach.
Solution Approach 2:
The system uses feedback from the flow machine's operating parameters to correct and validate the Doppler measurements. By continuously monitoring rotational speed and differential pressure, the system can identify when ambiguities occur in the Doppler spectrum and use the operating parameters to determine the correct flow velocity, creating a closed-loop measurement system that self-corrects.
2Speed
If high flow velocities are measured with long signal transit times, then flow velocity determination is achieved, but Nyquist sampling theorem is violated causing spectral ambiguities
Solution Approach 1:
The patent performs preliminary determination of the flow velocity range using the flow machine's operating parameters (rotational speed and differential pressure) before interpreting the Doppler spectrum. This preliminary action establishes the expected velocity range, which then guides the interpretation of the Doppler data and helps identify when aliasing has occurred, allowing for correct velocity determination despite the Nyquist violation.
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
Enables accurate determination of fluid flow velocity and volume flow through vascular support systems, even outside surgical scenarios, by resolving ambiguities using operating parameters like rotational speed and differential pressure, ensuring high precision and reliability.
Implementation Method 1
carrying out a pulsed Doppler measurement by means of an ultrasonic sensor (2) of the support system (1)
Data Source
AI summary
The invention relates to a method for determining at least a flow velocity or a fluid volume flow of a fluid flowing through an implanted vascular support system, comprising the following steps: a) carrying out a pulsed Doppler measurement by means of an ultrasonic sensor of the support system, b) evaluating a measurement result from step a), which has a possible ambiguity, c) providing at least one operating parameter of a flow machine of the support system, d) determining at least the flow velocity or the fluid volume flow using the measurement result evaluated in step b), wherein the possible ambiguity of the measurement result is corrected using the operating parameter.