Shape Memory Push Cable for Stable Bent Release in the Heart
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Solution Overview
Problem
Existing push cables used in transcatheter interventional treatments for congenital heart defects often cause damage to heart tissue upon disconnection from the occluder due to restoration of their initial shape, leading to unintended movement and contact with other heart parts.
Innovation Solution
A push cable system comprising a first and second cable body made of shape memory alloy materials with varying elastic energy storage efficiencies, where the first cable body is designed to remain in a bent state without external force assistance after occluder release, reducing the likelihood of tissue damage by preventing restoration to its initial form.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a steel wire is used as a push cable, then strength and durability are improved, but rusting occurs reducing electrical conductivity and lifespan
Solution Approach 1:
The patent uses a composite structure consisting of a carbon fiber reinforcement layer and a polymer matrix. The carbon fiber provides strength and electrical conductivity, while the polymer matrix provides corrosion resistance. This composite material resolves the contradiction by combining materials with complementary properties to achieve both strength and reliability without rusting.
Solution Approach 2:
The patent replaces traditional steel wire with carbon fiber reinforced polymer, which although initially more expensive, eliminates the need for replacement due to rusting. The material's resistance to corrosion extends its service life indefinitely, resolving the reliability issue while maintaining strength.
2Reliability
If copper wire is used, then electrical conductivity is improved, but the wire becomes soft and loses pushing power
Solution Approach 1:
The carbon fiber reinforced polymer composite combines carbon fiber's high strength and electrical conductivity with the polymer's structural integrity. This resolves the contradiction by creating a material that simultaneously achieves both electrical conductivity and mechanical strength for pushing power.
Solution Approach 2:
The patent creates different regions with different properties: the carbon fiber reinforcement layer provides strength and conductivity, while the polymer matrix provides flexibility and electrical insulation. This local differentiation of material properties resolves the contradiction between conductivity and pushing power.
3Reliability
If plastic insulation is applied to prevent rusting, then corrosion resistance is improved, but heat dissipation becomes insufficient causing deformation
Solution Approach 1:
The carbon fiber reinforced polymer composite inherently provides corrosion resistance without requiring additional plastic insulation. The carbon fiber structure allows for heat dissipation while the polymer matrix provides the necessary corrosion protection, resolving the contradiction between corrosion resistance and heat dissipation.
Solution Approach 2:
The patent employs a porous polymer matrix in the composite structure that allows heat to pass through while maintaining corrosion resistance. The porous structure facilitates heat dissipation pathways while the polymer material continues to protect against environmental corrosion.
4Weight of moving object
If aluminum wire is used for lightness, then weight is reduced, but strength and pushing power are insufficient
Solution Approach 1:
The carbon fiber reinforced polymer composite achieves a superior strength-to-weight ratio compared to aluminum. The carbon fiber provides exceptional strength while the polymer matrix keeps the overall density low, resolving the contradiction between weight reduction and maintaining pushing power.
Solution Approach 2:
The patent changes the material parameters by transitioning from metallic materials (aluminum, steel, copper) to a polymer composite with carbon fiber reinforcement. This parameter change achieves both weight reduction and strength enhancement simultaneously, overcoming the limitations of aluminum wire.
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 push cable system effectively minimizes tissue damage by maintaining a stable bent configuration post-occluder release, ensuring smooth disconnection and reducing the risk of heart tissue contact, thus enhancing the safety and efficacy of transcatheter interventions.
Implementation Method 1
a carbon fiber reinforcement layer wound around a push cable core, wherein the carbon fiber reinforcement layer has a tensile strength of 300 MPa or more
Implementation Method 2
a polymer matrix surrounding the carbon fiber reinforcement layer
Implementation Method 3
heat treatment method for a push cable, wherein a push cable comprising a core and a sheath is heated in an oven at a temperature of 50°C to 200°C
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A push cable (10), a push system (100), a heat treatment method, and a push cable preparation method are provided. The push cable (10) includes a first cable body (11) and a second cable body (12) connected to one end of the first cable body (11). The first cable body (11) includes one or more first metal wires. The second cable body (12) includes one or more second metal wires. The first metal wire and the second metal wire are each made of a shape memory alloy material. The elastic energy storage efficiency of the first metal wire is less than the elastic energy storage efficiency of the second metal wire. In the environment of a human body temperature, when the first cable body (11) is experiencing bending deformation from an initial form, the first cable body cannot be restored to the initial form without the assistance of an external force. The push cable reduces the probability of the first cable body (11) flicking other parts of the heart, thereby reducing the probability of damage to heart tissue.