Multi-layer Implantable Stent Frame Reducing Foreshortening

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Solution Overview

Problem

Implantable medical devices, such as heart valve stents, experience significant foreshortening during deployment, making valve positioning difficult and increasing the risk of dislodging calcified plaques due to the change in length between radially contracted and expanded states, which complicates insertion and alignment.

Innovation Solution

A frame design for implantable medical devices featuring multiple layers with independent length changes, where one layer extends beyond the other, reducing the extent of foreshortening while maintaining radial stiffness, and utilizing additive manufacturing for precise strut formation and coupling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a conventional single-layer metal frame is used for implantable medical devices, then the device can be manufactured with simple structure, but the device experiences significant foreshortening during deployment making valve positioning difficult and increasing the risk of dislodging calcified plaques

Engineering Contradiction:

Improveframe structureVSAvoidvalve positioning

Core Design Contradiction:

Device complexityVSEase of operation

Solution Approach 1:

The frame is divided into multiple independent layers (first layer and second layer), each capable of independent radial expansion. This segmentation allows different layers to manage different aspects of deployment, with the first layer providing primary structural support and the second layer reducing foreshortening effects, thereby improving positioning accuracy without excessive complexity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention transitions from a single-layer two-dimensional structure to a multi-layer three-dimensional structure. The overlapping arrangement of first and second layers creates additional structural dimensions that compensate for foreshortening while maintaining manufacturing feasibility through modular construction

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Device complexity

If a conventional single-layer metal frame is used for implantable medical devices, then the device structure remains simple, but the device length changes significantly between radially contracted and expanded states increasing the risk of dislodging calcified plaques

Engineering Contradiction:

Improveframe structureVSAvoidplaque stability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The multi-layer overlapping structure acts as a cushioning mechanism that absorbs and distributes the mechanical stresses of deployment. The second layer, overlapping the first layer, provides a buffer that reduces the abrupt length changes that could dislodge plaques, preparing the structure in advance to handle deployment forces

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Ease of operation

If multiple layers with independent length changes are used in the frame design, then foreshortening is reduced and positioning is improved, but the device complexity increases

Engineering Contradiction:

Improvedevice positioningVSAvoidframe structure

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The frame layers are arranged in a nested configuration where the second layer overlaps and is positioned relative to the first layer. This nesting allows the multi-layer structure to achieve foreshortening reduction while maintaining a compact form factor that limits the increase in overall device complexity

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

Inventive Principle:

Principle #1Segmentation

4Manufacturing precision

If additive manufacturing is used for precise strut formation and coupling, then manufacturing precision is improved, but the manufacturing process complexity increases

Engineering Contradiction:

Improvestrut formationVSAvoidmanufacturing process

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The invention combines multiple struts and layers into integrated structures where struts from the first and second layers are coupled together. This merging allows additive manufacturing to create complex multi-layer configurations in a single process, improving precision while the modular nature of the coupled struts maintains manufacturing ease through standardized connection points

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS11259918B2Frame for an implantable medical device and a method of manufacturing a frame for an implantable medical device

Publication Date: 2022.03.01 CARENA HEALTHCARE LTD

AI summary

A frame for an implantable medical device, comprising: a first member, comprising a plurality of struts defining a plurality of cells, wherein the first member is annular and defines a longitudinal direction which is parallel to the axis of the first member, a radial direction, and a circumferential direction; a second member, comprising a plurality of struts and coupled to the first member at circumferentially distributed locations; wherein the second member overlaps a first end portion of the first member and extends beyond the first end portion of the first member.