Left Ventricular Assist Pump with Segmented Rotor-Stator and Casing
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Solution Overview
Problem
Current left ventricular cardiac assist devices face challenges in achieving optimal blood circulation and minimizing risks of haemolysis and thrombosis, while also requiring a compact design to reduce infection risk and allow for easy removal when the left ventricle recovers.
Innovation Solution
A left ventricular cardiac assist pump with a spindle-shaped rotor-stator assembly and a separate casing that provides a large cross-sectional passage for blood flow, minimizing sudden direction changes and using electromagnetic bearings for efficient operation, along with a unique implantation method that positions the pump in series with the left ventricle, allowing for natural blood circulation and pulsatility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a compact pump design is used to reduce infection risk and allow easy removal, then device size is reduced, but blood circulation efficiency and flow area are compromised
Solution Approach 1:
The pump is divided into functionally independent modules: a compact rotor-stator assembly for pumping and a separate casing that forms the blood flow passage. This segmentation allows the pumping mechanism to be small while the flow passage can be optimized for efficient blood circulation, resolving the contradiction between compact size and circulation efficiency.
Solution Approach 2:
The invention transitions from traditional axial or radial flow configurations to a mixed-flow design where blood moves through a three-dimensional passage that combines axial and radial components. This dimensional approach maximizes flow area within a compact pump footprint, improving blood circulation efficiency without increasing overall device volume.
2Ease of operation
If the pump is designed with a compact size for easy removal and reduced infection risk, then implantation simplicity is improved, but electromagnetic motor performance deteriorates due to limited space for stator and rotor
Solution Approach 1:
The electromagnetic motor is segmented into a rotor-stator assembly that is functionally separated from the blood flow passage (casing). This allows the motor components to be tightly packed for compactness while the casing provides the necessary space for efficient electromagnetic field generation, maintaining motor performance in a compact configuration.
Solution Approach 2:
The casing acts as a flexible boundary that defines the blood flow passage while accommodating the rigid rotor-stator assembly. This separation allows the electromagnetic components to be designed for optimal performance in a compact space, with the casing providing the necessary clearance and flow passage without adding significant volume.
3Use of energy by moving object
If a small gap between rotor and stator is used to improve electromagnetic cooperation, then motor efficiency is improved, but blood flow passage area is reduced
Solution Approach 1:
The design segments the electromagnetic motor ( rotor-stator with small gap) from the blood flow passage (casing). The rotor-stator assembly maintains a small gap for efficient electromagnetic coupling, while the separate casing provides an independent, optimally sized blood flow passage. This functional segmentation resolves the contradiction between motor efficiency and flow area.
4Reliability
If a bypass arrangement is used to assist the left ventricle, then cardiac function is improved, but infection risk increases due to larger implantation area
Solution Approach 1:
The pump is designed as a compact, self-contained device with segregated functions (motor and flow passage), minimizing the overall implantation footprint. This compact segmentation reduces the surface area exposed to potential pathogens, lowering infection risk while maintaining effective cardiac assistance through the efficient rotor-stator-casing configuration.
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
The pump achieves efficient blood circulation with reduced risks of haemolysis and thrombosis, maintains natural blood flow dynamics, and allows for easy removal when the left ventricle recovers, minimizing infection risk due to its compact size and efficient implantation.
Implementation Method 1
an upstream electromagnetic bearing magnets assembly, upstream electromagnetic bearing stator windings, a downstream electromagnetic bearing magnets assembly and downstream electromagnetic bearing stator windings
Implementation Method 2
the impeller, which is of the centrifugal type, with blood being driven towards the casing
Implementation Method 3
the rotor comprises an impeller and a shaft, the stator is positioned around the shaft, the rotor-stator assembly forming a spindle-shaped assembly
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A left ventricular cardiac assist pump, including an inlet opening (18) and a discharge opening (20) aligned in an axial direction, the pump including a casing (11) spaced from a stator (13) and a rotor (12) comprising an impeller (16) and a shaft (17), with at least one connecting spacer (14) connecting the casing (11) and the stator (13), the impeller (16) being configured to direct the blood towards the casing (11) and the discharge opening (20), whereby blood flows through the pump principally between the casing (11) and the rotor-stator assembly (15). The casing (11) and the connecting spacers (14) are each formed of a mesh structure (125, 126) made of a resilient shape memory material.