Interatrial Shunt Structure for Reversible In Vivo Flow Adjustment
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Solution Overview
Problem
Existing implantable devices for adjusting fluid flow in the human body, such as interatrial shunts, face limitations in reversibility and stability, leading to hysteresis effects, stress, fatigue, and irreversible deformation, which can result in device failure and inadequate regulation of blood flow.
Innovation Solution
Development of implantable devices with composite structures exhibiting superelastic and shape-memory properties, allowing for reversible adjustment of dimensions through mechanical deformation and temperature-induced crystalline phase changes, using materials like NITINOL with specific austenitic finish temperatures, enabling in vivo expansion and contraction of the passageway.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing implantable devices are used to adjust fluid flow, then fluid flow regulation is achieved, but device stability and reliability deteriorate due to hysteresis effects, stress, fatigue, and irreversible deformation
Solution Approach 1:
The patent applies parameter changes by utilizing temperature-induced phase transitions in shape memory materials. The device transitions between martensitic (deformed) and austenitic (recovered) phases through controlled heating and cooling, enabling reversible dimensional changes without permanent deformation. This resolves the contradiction by allowing the device to maintain dimensional stability through reversible phase changes rather than irreversible plastic deformation.
Solution Approach 2:
The patent employs composite materials combining shape memory alloys (such as Nitinol) with other materials to create a device that exhibits both superelasticity and shape memory effects. This composite structure enables the device to withstand stress and fatigue while maintaining reliability through reversible dimensional adjustments, directly addressing the contradiction between reliability and dimensional stability.
2Adaptability or versatility
If device dimensions are adjusted in vivo, then fluid flow control is improved, but device complexity increases due to reversible adjustment mechanisms
Solution Approach 1:
The patent applies self-service by designing the device to automatically adjust its dimensions through temperature-induced phase transitions. The shape memory material self-regulates its configuration in response to thermal changes, eliminating the need for complex external actuation mechanisms. This resolves the contradiction by providing flow regulation flexibility through a self-adjusting mechanism rather than a complex controlled system.
Solution Approach 2:
The patent replaces complex mechanical adjustment mechanisms with a thermal-field-based approach. Instead of using motors, pistons, or linkages to adjust device dimensions, the invention uses temperature-controlled phase transitions in shape memory materials to achieve dimensional changes. This substitution reduces structural complexity while maintaining adaptability for flow regulation.
3Duration of action of stationary object
If superelastic and shape-memory materials are used, then device reversibility is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies local quality by creating zones with different austenitic finish temperatures within the shape memory material structure. Different portions of the device can be heat-treated to exhibit phase transitions at different temperatures, allowing for controlled sequential activation of dimensional changes. This approach manages manufacturing precision requirements by distributing temperature control across different zones rather than requiring uniform precision throughout the entire device.
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 devices provide precise and reversible control of fluid flow by adjusting the cross-sectional area of the passageway, simplifying catheter manipulations and reducing the risk of device failure, thus effectively managing conditions like heart failure and pulmonary hypertension.
Implementation Method 1
exhibiting superelastic and shape-memory properties, allowing for reversible adjustment of dimensions through mechanical deformation and temperature-induced crystalline phase changes
Implementation Method 2
exhibiting superelastic and shape-memory properties, allowing for reversible adjustment of dimensions through mechanical deformation
Implementation Method 3
using materials like NITINOL with specific austenitic finish temperatures, enabling in vivo expansion and contraction of the passageway
Data Source
AI summary
Devices are provided with an internal dimension that can be reduced and increased in vivo. In one example, an interatrial shunt for placement at an atrial septum of a patient's heart includes a body. The body includes first and second regions coupled in fluid communication by a neck region. The body includes a shape-memory material. The body defines a passageway through the neck region for blood to flow between a first atrium and a second atrium. The first and second regions are superelastic at body temperature, and the neck region is malleable at body temperature. A flow area of the passageway through the neck region may be adjusted in vivo.