Variable-Gap Impeller for High-Flow Blood Pumping
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Solution Overview
Problem
Existing mechanical circulatory support devices face challenges in optimizing blood flow while minimizing the risk of hemolysis and device damage, particularly in high-flow scenarios for patients with mild cardiogenic shock or high-risk percutaneous coronary intervention.
Innovation Solution
The design incorporates an impeller with a variable outer diameter and a varying radial gap between the impeller blades and the tubular cannula, featuring distinct radial gaps in the distal and outflow regions to enhance efficiency and reduce hemolysis, with the distal region having a minimized radial gap and the outflow region having a larger gap to accommodate blood flow without increasing device wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the radial gap between the impeller and tubular cannula is minimized to enhance pumping efficiency, then blood flow rate increases, but the risk of hemolysis and device damage increases
Solution Approach 1:
The patent applies local quality by implementing different radial gap sizes in different regions of the impeller. The distal region has a minimized radial gap (0.05-0.15mm) to maximize pumping efficiency, while the proximal region has an enlarged radial gap (0.20-0.50mm) to reduce hemolysis and device damage. This spatial variation in gap quality allows each region to optimize for its specific functional requirements.
Solution Approach 2:
The impeller is segmented into distinct radial gap regions - a distal region with minimized gap and a proximal region with enlarged gap. This segmentation allows the device to simultaneously achieve high pumping efficiency in the distal region while protecting against hemolysis and damage in the proximal region, resolving the contradiction between productivity and safety.
2Productivity
If the impeller outer diameter is increased to improve blood flow capacity, then flow rate increases, but the risk of device damage and hemolysis increases
Solution Approach 1:
The patent implements a dynamic impeller design where the outer diameter varies along the axial length. The distal portion has a larger outer diameter (4.0-6.0mm) to maximize flow capacity, while the proximal portion has a smaller outer diameter (2.0-4.0mm) to reduce damage risk. This dynamic variation in geometry allows the impeller to adapt its flow capacity and safety characteristics along its length.
Solution Approach 2:
Different sections of the impeller are assigned different outer diameter qualities - the distal section has larger diameter for flow capacity while the proximal section has smaller diameter for safety. This local differentiation resolves the contradiction between maximizing blood flow capacity and minimizing device damage and hemolysis.
3Productivity
If the radial gap is uniformly minimized throughout the impeller to maximize pumping efficiency, then flow rate increases, but hemolysis and device wear increase
Solution Approach 1:
The impeller is divided into functional segments with different radial gap characteristics. The distal segment operates with minimized gap for high pumping efficiency, while the proximal segment operates with enlarged gap to protect against hemolysis and wear. This segmentation allows the system to generate harmful factors only where necessary for performance while protecting critical components.
Solution Approach 2:
The radial gap quality varies locally along the impeller length - minimized in the distal region for efficiency and enlarged in the proximal region for protection. This local quality variation enables the system to achieve high pumping efficiency without uniformly increasing hemolysis and device wear throughout the entire impeller.
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 configuration allows for higher blood flow rates with reduced hemolysis and device damage by optimizing the radial gaps, enhancing the mechanical circulatory support system's performance and safety.
Implementation Method 1
an impeller rotated by the motor that moves blood through the tubular inflow cannula and out through the outflow area
Implementation Method 2
an impeller rotated by the motor that moves blood through the tubular inflow cannula and out through the outflow area
Data Source
AI summary
The present disclosure is directed generally to mechanical cardiovascular support systems used in the medical field to assist the movement of blood. In particular the present disclosure is directed to an impeller having features that allow improved performance. An annular flow area around a rotating impeller may be variable along the axial length of the impeller. A first radial gap, between a distal region of the impeller and a surrounding tubular housing, may be greater or smaller than a second radial gap, between a proximal region of the impeller and the surrounding tubular housing.