Non-Pulsatile Ventricular Assist Pump With Within-Beat Speed Control
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Solution Overview
Problem
Non-pulsatile ventricular assist devices (VADs) cause an increased tendency to bleeding due to von Willebrand factor (vWF) deficiency, and they reduce blood pressure pulsatility, leading to inadequate perfusion of the microvasculature.
Innovation Solution
An event-based within-a-beat control strategy for the rotational speed of VADs, using an open-loop or closed-loop control system to generate a desired minimum pulsatility in the arterial blood pressure, synchronizing speed alterations with cardiac events to restore and maintain physiological pulsatility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a non-pulsatile VAD operates at constant rotational speed, then the VAD provides stable blood flow and pressure support, but it causes vWF deficiency and reduces blood pressure pulsatility leading to inadequate microvasculature perfusion
Solution Approach 1:
The patent applies periodic action by modulating the rotational speed of the VAD rotor in a periodic manner that synchronizes with the cardiac cycle. The control device varies the rotational speed between different levels during systole and diastole, creating artificial pulsatility in the blood flow and pressure waveform. This periodic speed modulation restores the physiological pulsatility needed for vWF function and microvasculature perfusion while maintaining adequate overall blood flow support.
Solution Approach 2:
The patent implements dynamics by transitioning from a static constant-speed operation to a dynamic variable-speed operation. The control device continuously adjusts the rotational speed of the VAD rotor based on detected cardiac cycle events, making the pump adaptable to the physiological requirements of different cardiac phases. This dynamic speed adjustment allows the VAD to provide both stable flow support and physiological pulsatility.
2Object-affected harmful factors
If the rotational speed of VAD is varied within a cardiac cycle to restore pulsatility, then vWF deficiency is reduced and microvasculature perfusion is improved, but the control system complexity increases
Solution Approach 1:
The patent employs feedback control by using a control device that detects cardiac cycle events (such as ECG signals or pressure waveform features) and uses this information to adjust the rotational speed of the VAD rotor. The control device receives feedback about the cardiac phase and modulates the pump speed accordingly, creating a closed-loop system that automatically restores pulsatility without requiring complex external control systems.
Data Source
AI summary
A control device (100) for controlling the rotational speed (nVAD(t)) of a non-pulsatile ventricular assist device, VAD, (50) uses an event-based within-a-beat control strategy, wherein the control device is configured to alter the rotational speed of the VAD within the cardiac cycle of the assisted heart and to synchronize the alteration of the rotational speed with the heartbeat by at least one sequence of trigger signals (σ(t)) that is related to at least one predetermined characteristic event in the cardiac cycle. Further, a VAD (50) for assistance of a heart comprises the control device (100) for controlling the VAD, wherein the VAD is preferably a non-pulsatile rotational, for example catheter-based, blood pump.