Double Suction Centrifugal Blood Pump With Single-Inlet Flow Split
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Solution Overview
Problem
Current mechanical circulatory support devices, such as centrifugal blood pumps, face complications including infection, thrombus formation, embolic and hemorrhagic strokes, and blood damage due to design limitations like bifurcated inflow tubes, side holes, and narrow leakage flow paths, which are too large for implantation in the left ventricle and cause high shear stress.
Innovation Solution
A double suction centrifugal pump design with blood-immersed cone bearings and a shroud-less configuration, utilizing a single inlet and outflow conduit, eliminates secondary flow paths and supports the rotor with cone bearings, reducing shear stress and thrombus formation, and incorporating a percutaneous power cable for infection prevention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a bifurcated inflow tube with two inflow conduits is used to create a double suction pump, then the pump can achieve double suction capability, but the pump size becomes too large to implant within the pericardium
Solution Approach 1:
The single inflow tube is segmented into two separate flow paths that feed the two impellers back-to-back, eliminating the need for a bifurcated tube structure. This segmentation allows double suction capability while maintaining a compact single-tube configuration that fits within the pericardium.
Solution Approach 2:
The patent transitions from a conventional side-by-side impeller arrangement to a back-to-back configuration where impellers face opposite directions along the same axis. This dimensional reorganization allows both impellers to be fed by a single inflow tube while maintaining double suction functionality, reducing the overall pump footprint.
2Device complexity
If side holes are used in the inflow tube to supply blood to both impellers, then the pump structure is simplified, but hemolysis occurs due to high shear stress at the holes
Solution Approach 1:
The harmful side holes are completely removed from the design. Instead of using holes in the inflow tube to feed the impellers, the patent extracts this function to separate inflow channels that guide blood flow smoothly to each impeller inlet, eliminating the shear stress concentration that causes hemolysis.
Solution Approach 2:
The patent introduces smooth transition channels as intermediary flow paths between the single inflow tube and the two impeller inlets. These intermediary channels distribute blood flow evenly without creating high shear stress zones, mediating between the simplified single-tube structure and the requirement to avoid hemolysis.
3Reliability
If magnetic levitation windings surround the pump impellers, then the pump achieves magnetic suspension, but the pump becomes too complex and large to implant in the apex of the left ventricle
Solution Approach 1:
The complex magnetic levitation windings surrounding the impellers are extracted and replaced with a simpler magnetic bearing system. The patent uses magnetic bearings to support the impeller shaft, achieving reliable magnetic suspension without the bulky winding structures that increase pump size and complexity.
Solution Approach 2:
The patent replaces the mechanical winding-based magnetic levitation system with a more compact magnetic bearing system. This substitution maintains the non-contact suspension capability while dramatically reducing the structural complexity and size, making the pump suitable for apex implantation.
4Device complexity
If axial flow pump design is used, then the pump structure is simple, but blood damage is higher compared to centrifugal pumps
Solution Approach 1:
The patent changes the fundamental flow pattern parameter from axial to radial flow through the impellers. This parameter change transitions the pump mechanism to a centrifugal design that generates lower shear stress on blood cells, reducing hemolysis and thrombus formation while maintaining acceptable structural complexity through the back-to-back 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 design achieves reduced adverse events, lower thrombus formation, minimized blood damage, and a more compact, energy-efficient pump suitable for long-term implantation with reduced risk of serious strokes and extended battery life.
Implementation Method 1
blood immersed bearings to levitate the pump rotor
Implementation Method 2
double suction centrifugal pump design
Data Source
Figure 1
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AI summary
A centrifugal blood pump uses the "double suction" arrangement of the blood flow channels, by dividing the blood flow across the impeller into two practically identical streams, one flowing across the upstream side of the impeller and the other flowing across the downstream side. The double suction arrangement is obtained by using a "flow through cone bearing" mounted to the hub of the impeller. The impeller is attached to the driving motor by three posts, which do not significantly diminish the flow area. The annular flow through the motor "air gap" reaches the flow channel as a single stream and divides into two streams in the vicinity of the posts. The flow is distributed equally to the two sides of the impeller. After passing across the impeller the two streams combine into one that enters the spiral volute and continues past the pump cutwater and through the outflow channel.