Ventricular Assist Device Flow Control via Diastolic Gradient
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Solution Overview
Problem
Current ventricular assist devices (VADs) lack a physiological pump flow controller, limiting patients' ability to increase cardiac output during exercise due to weak preload and strong afterload sensitivities, and existing solutions face challenges with implanted sensors that are impractical for long-term use.
Innovation Solution
An electronic processing device determines a flow rate gradient during diastole to derive blood pressure parameter values and control the VAD, adjusting impeller rotation to optimize blood flow and reduce ventricular filling pressure, without the need for implanted sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fixed-speed impeller is used in the VAD, then the device structure is simple and reliable, but the cardiac output cannot be adequately increased during exercise due to weak preload sensitivity
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed-speed impeller to a variable-speed impeller that can dynamically adjust its rotation speed based on real-time detection of physiological parameters (such as flow rate, pressure, or ECG signals). This allows the VAD to adapt its cardiac output to match the patient's exercise intensity and metabolic demands, resolving the contradiction between structural simplicity and physiological adaptability during exercise
2Measurement precision
If implanted sensors are used to monitor haemodynamic parameters, then precise control of pump flow is achieved, but thrombosis, malfunction, calibration difficulties, and high cost occur
Solution Approach 1:
The patent extracts the sensing function from implanted sensors and relocates it to external or non-invasive detection methods. By using sensors placed outside the bloodstream (such as on the skin surface or in external monitoring devices), the system achieves precise haemodynamic parameter detection without the thrombosis and reliability issues associated with implanted sensors, while still enabling precise pump flow control through feedback
3Productivity
If the VAD relies on preload variations to control pump output, then the control mechanism is passive, but the increase in cardiac output during exercise is modest compared to physiological response
Solution Approach 1:
The patent implements feedback control by continuously monitoring haemodynamic parameters (such as flow rate, pressure, or cardiac rhythm) and using this information to actively adjust the impeller speed. This closed-loop feedback system enables the VAD to proactively increase cardiac output in response to exercise demands, transforming the passive preload-dependent control into an active, physiologically-responsive control mechanism that matches normal cardiac behavior
Data Source
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AI summary
Apparatus for use with a ventricular assist device that is assisting cardiac function of a biological subject, the apparatus including an electronic processing device that determines a flow rate of blood through the ventricular assist device, analyses the flow rate to determine a flow parameter value at least partially indicative of a change in the flow rate during diastole; and uses the flow parameter value to either derive at least one blood pressure parameter value at least partially indicative of a blood pressure in the biological subject or control the ventricular assist device.