Radiopaque Cannula Marker Using Heat Shrink Nesting
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Solution Overview
Problem
Intracardiac and intravascular blood pumps with low radiopacity materials pose challenges in accurate positioning during medical procedures due to reduced visibility under X-ray or fluoroscopic imaging, which can impact their proper function.
Innovation Solution
A method of applying a radiopaque marker to the cannula of these pumps using a radiopaque polymer band or metallic element, integrated through a heat shrink tube process, ensuring minimal size and surface disruption, maintaining a smooth surface free of sharp edges or roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If a radiopaque marker is added to the cannula to improve visibility during imaging, then the visibility is improved, but the outer diameter of the cannula increases
Solution Approach 1:
The radiopaque band is placed inside the heat shrink tube, which then shrinks around it, nesting the marker within the cannula structure. This allows the marker to be contained within the existing outer diameter envelope while still providing radiopacity for imaging visibility.
Solution Approach 2:
The heat shrink tube acts as a flexible shell that conforms to the cannula surface when heated. This thin film approach allows the radiopaque marker to be applied without significantly increasing the cannula's outer diameter, as the tube shrinks to wrap tightly around the existing structure.
2Difficulty of detecting and measuring
If a radiopaque marker is applied to the cannula surface, then visibility is improved, but surface roughness or sharp edges may be created promoting haemolysis or thrombus
Solution Approach 1:
The heat shrink tube forms a smooth, continuous flexible shell over the radiopaque band and cannula surface. When heated, it shrinks to create a uniform, rounded outer surface that eliminates sharp edges and roughness, preventing blood cell damage and thrombus formation while maintaining the underlying radiopaque marker.
Solution Approach 2:
The heat shrink tube serves as a protective cushioning layer applied before the cannula is implanted. It pre-smooths the surface irregularities that would otherwise be present from the radiopaque band application, preventing harmful effects to blood cells and preventing clot formation.
3Length of stationary object
If the cannula is miniaturized for percutaneous insertion, then ease of insertion is improved, but radiopacity and visibility are reduced
Solution Approach 1:
Instead of making the entire cannula radiopaque (which would increase diameter), the radiopaque band is applied locally to specific portions of the cannula where visibility is needed during insertion and positioning. This localized approach maintains miniaturization while providing sufficient imaging visibility at critical locations.
Solution Approach 2:
The radiopaque band is nested within the heat shrink tube and cannula structure, allowing the marker to be incorporated into the miniaturized design without adding significant outer diameter. The nested configuration enables the radiopaque material to be contained within the existing size envelope.
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 radiopaque marker enhances visibility during medical procedures without increasing the cannula's outer diameter or causing surface irregularities, promoting safe and accurate implantation while maintaining the cannula's structural integrity and reducing risks of haemolysis or thrombus formation.
Implementation Method 1
heating the band and the polymer tube to: soften the band, cause the heat shrink tube to shrink and apply force on the softened band towards the cannula
Implementation Method 2
cause the heat shrink tube to shrink and apply force on the softened band towards the cannula
Implementation Method 3
obtain a band of radiopaque polymer material... enhance visibility during medical procedures
Data Source
Figure 1
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AI summary
A method is disclosed of applying a radiopaque marker to a cannula for use with an intracardiac pump, the method including: obtaining a band of radiopaque polymer material; placing the band around an outer diameter of the cannula, the cannula including a flexible tubular wall formed around and supported by a coil of shape memory material; placing a heat shrink tube around the band and the cannula; heating the band and the polymer tube to: soften the band, cause the heat shrink tube to shrink and apply force on the softened band towards the cannula, and cause the softened band to be welded to the cannula to form a radiopaque marker in a portion of the tubular wall; and removing the heat shrink tube.