Blood Pump Speed Control for Thrombus Prevention
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Solution Overview
Problem
Rotary blood pumps face challenges in maintaining effective blood delivery while minimizing thrombus formation and turbulence, particularly at speeds below the design speed, which can lead to blockages and impaired function.
Innovation Solution
The blood pump operates alternately at low and design speeds, with rapid acceleration to design speed to prevent thrombus formation, and deceleration without external energy to maintain effective flow rates, using a DC motor with cyclically excited windings and permanent magnets, controlled by a remote controller to vary flow rates and synchronize with heart function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the blood pump operates at low speed below design speed, then energy consumption is reduced and flow rate is adjusted to match patient needs, but thrombus formation and turbulence increase
Solution Approach 1:
The patent applies periodic acceleration pulses at design speed superimposed on the low-speed operation. These periodic high-speed pulses prevent thrombus formation by periodically clearing blood stasis and turbulence, while the base low-speed operation maintains energy efficiency and matches patient flow requirements.
Solution Approach 2:
The patent dynamically adjusts the pump speed by superimposing acceleration pulses on the base low-speed operation. This dynamic speed modulation allows the system to maintain low average speed for energy efficiency while periodically achieving design speed to prevent thrombus formation, resolving the contradiction between energy consumption and thrombus prevention.
2Reliability
If the blood pump operates constantly at design speed, then thrombus formation is prevented, but energy consumption increases and flow rate flexibility is reduced
Solution Approach 1:
Instead of continuous high-speed operation, the patent uses periodic acceleration pulses at design speed superimposed on low-speed operation. This periodic action maintains thrombus prevention effectiveness while dramatically reducing average energy consumption and allowing flow rate adjustment to match patient needs.
Solution Approach 2:
The patent changes the speed parameter dynamically by superimposing acceleration pulses on the base operating speed. This parameter modulation allows the system to achieve thrombus prevention at design speed only when necessary, while maintaining lower average speed for energy efficiency and flow rate flexibility.
3Adaptability or versatility
If the blood pump operates at low speed, then flow rate is reduced to match patient needs, but blood delivery effectiveness decreases
Solution Approach 1:
The patent uses periodic acceleration pulses to periodically enhance blood delivery effectiveness even during low-speed operation. These pulses ensure adequate blood propelling during critical moments while maintaining low average flow rate to match patient needs, resolving the contradiction between adaptability and productivity.
4Speed
If the impeller is designed for minimal stalls at design speed, then turbulence is minimized at high speed, but performance at low speed deteriorates with increased stalls and turbulence
Solution Approach 1:
The patent periodically activates the impeller at design speed to clear stalls and reduce turbulence that accumulate during low-speed operation. This periodic high-speed activation maintains impeller performance and reduces turbulence without requiring continuous high-speed operation, thus resolving the contradiction between design speed performance and low-speed turbulence.
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 approach prevents thrombus buildup, allows flexible flow rate adjustment, and provides pulsatile support to the heart, ensuring effective blood delivery and minimizing turbulence, even at lower speeds, without constant high-speed operation.
Implementation Method 1
The rotor is a DC motor without a slip ring, which has cyclically excited windings in the stator and permanent magnets in the rotor
Implementation Method 2
The rotor is connected to an impeller that rotates in a pump ring
Data Source
Figure 1~2
Figure 3~5
AI summary
The blood pump is sometimes operated at a lower speed than its design speed. This poses a risk of thrombus formation because flow separation can occur on the impeller blades of the rotary blood pump. To clear deposits from the impeller, the pump speed is temporarily increased to the design speed. Alternatively, the pump can operate alternately at its design speed and a lower speed, with this pulsed operation synchronized to the heart rate.