Inlet Cannula with Segmented Zones for Heart Pump Thrombus Prevention
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Solution Overview
Problem
Existing inlet cannulas for heart pumps face a high risk of thrombus formation and clogging due to disturbed blood flow, which can lead to thrombi being introduced into the cannula and subsequently the blood pump.
Innovation Solution
The design incorporates an ingrowth zone with increased surface roughness and an inlet zone with minimal surface roughness, separated by a flow separation edge that increases wall shear stress, reducing the risk of thrombi formation and ensuring undisturbed fluid flow, using a hemocompatible material like titanium or stainless steel, and optionally featuring texturing and a lattice element to prevent thrombi entry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the inlet cannula surface is polished to minimize surface roughness for uniform blood flow, then fluid flow is improved, but the cannula cannot grow into the ventricle wall
Solution Approach 1:
The inlet cannula surface is divided into two distinct zones: a polished inlet zone with minimal surface roughness for uniform blood flow, and a structured ingrowth zone with increased surface roughness for ventricle wall integration. This segmentation allows each zone to optimize its specific function without compromising the other.
Solution Approach 2:
Different surface qualities are applied to different regions of the inlet cannula. The inlet zone features a smooth, polished surface to minimize flow disturbance, while the outer surface features a structured, rougher surface to promote tissue ingrowth and stable integration into the ventricle wall.
2Stability of the object's composition
If the inlet cannula has a structured region with increased surface roughness for ventricle wall integration, then stability is improved, but blood flow is disturbed and thrombus formation risk increases
Solution Approach 1:
The inlet cannula is segmented into a structured ingrowth zone for stability and a polished inlet zone for safe fluid flow. This spatial separation ensures that the structured region promoting integration does not come into contact with the blood flow, thereby eliminating the thrombus formation risk associated with rough surfaces.
Solution Approach 2:
The surface quality is localized to specific regions: the outer surface has a structured, rough texture for tissue integration, while the inner inlet surface is smooth and polished to maintain laminar blood flow and prevent thrombus formation.
3Ease of manufacture
If the inlet zone and ingrowth zone are smoothly transitioned, then manufacturing is simplified, but flow separation and thrombus risk occur
Solution Approach 1:
The inlet zone and ingrowth zone are clearly segmented and separated by a distinct flow separation edge, eliminating gradual transitions. This sharp demarcation prevents flow separation and thrombus formation while remaining manufacturable through processes like selective polishing or additive manufacturing.
Solution Approach 2:
Instead of using a smooth gradual transition between zones, the design employs a sharp, well-defined flow separation edge. This inverted approach—using a discontinuous rather than continuous transition—effectively prevents flow disturbance and thrombus formation.
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 solution minimizes thrombi formation and ensures undisturbed fluid flow into the cannula and pump, reducing the risk of clogging and maintaining high wall shear stress, thereby enhancing the reliability of the fluid pump system.
Implementation Method 1
a flow separation edge that increases wall shear stress
Data Source
AI summary
An inlet cannula is provided for supplying a fluid from a human vessel to a fluid pump, the inlet cannula formed as a hollow structure suitable for conveying the fluid and a surface of the inlet cannula has an ingrowth zone and an inlet zone separated from each other by a tear-off edge extending in the circumferential direction of the inlet cannula, wherein a first tangent to the inlet zone on the tear-off edge has an angle to a longitudinal axis of the inlet cannula of >0° and <180°, and wherein a surface roughness in the ingrowth zone is greater than a surface roughness in the inlet zone, and wherein along the flow direction the ingrowth zone is concave, convex, or not curved and the inlet zone is convexly curved, and wherein the tear-off edge forms a curvature transition between the ingrowth zone and the inlet zone.