Basket Catheter Spines with Localized Flexibility for Tissue Safety
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Solution Overview
Problem
Basket-shaped electrophysiology catheters face challenges in achieving sufficient flexibility to minimize tissue damage while maintaining effective tissue contact and electrode spacing, particularly in varying atrial sizes and shapes, due to the risk of injury from stiffer spines.
Innovation Solution
The catheter features spines with varying flexibility, including regions of greater and lesser flexibility, designed to deform predictably under axial forces, allowing for axial compression and absorption of excessive forces, thereby minimizing tissue damage while maintaining tissue contact and electrode spacing, utilizing Nitinol alloys for shape memory properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If stiffer spines are used in the basket catheter, then better tissue contact is achieved, but the risk of injury and damage to the atrial wall increases
Solution Approach 1:
The spines are constructed with non-uniform cross-sections featuring notches or reduced-thickness regions at specific locations. This creates zones of varying flexibility along the spine length, where certain segments are more compliant than others. The stiffer regions provide structural support and tissue contact capability, while the softer notched regions reduce stress concentration and minimize tissue damage risk during expansion and contact.
Solution Approach 2:
Each spine is divided into multiple segments with different structural characteristics through the introduction of notches or varied cross-sectional geometries. These segmented regions allow different parts of the same spine to exhibit different mechanical properties - some portions are designed to be more flexible while others maintain stiffness, enabling the spine to function as a composite structure with localized functionality.
2Object-affected harmful factors
If the basket assembly is made more flexible to minimize tissue damage, then tissue contact safety improves, but the ability to maintain electrode spacing and effective tissue contact deteriorates
Solution Approach 1:
The spines incorporate non-uniform cross-sections with strategic notches that create localized flexibility zones. The regions with notches or reduced thickness provide enhanced flexibility and compliance to minimize tissue damage, while the fuller, thicker sections between notches maintain sufficient stiffness to preserve electrode spacing and ensure effective tissue contact when the basket is expanded.
3Object-affected harmful factors
If spines are designed to deform predictably under axial force, then shock absorption capability improves, but structural rigidity may be compromised
Solution Approach 1:
The spines feature non-uniform cross-sections with notches or reduced-thickness regions positioned to create predictable deformation zones. When axial forces are applied during basket expansion or when contacting tissue, these notched regions are designed to flex and absorb shock in a controlled manner, while the overall spine structure maintains sufficient rigidity through its broader geometric configuration and material properties.
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 catheter effectively absorbs and dampens forces that could damage tissue, ensuring reliable contact and spacing without increasing the risk of injury, enabling precise mapping and ablation in cardiac procedures.
Implementation Method 1
Nitinol belongs to a class of materials called Shaped Memory Alloys (SMA). These materials have interesting mechanical properties beyond flexibility and elasticity, including shape memory and superelasticity which allow nitinol to have a 'memorized shape.'
Implementation Method 2
Nitinol has different temperature phases, including martensitic phase and austenite phase. The austenite phase is Nitinol's stronger, higher-temperature phase. Crystalline structure is simple cubic. Superelastic behavior occurs in this phase (over a 50°-60° C. temperature spread).
Implementation Method 3
At body temperature, nitinol wire is flexible and elastic and like most metals nitinol wires deform when subjected to minimal force and return to their shape in the absence of that force.
Data Source
AI summary
A catheter with basket-shaped electrode assembly with spines configured for hyper-flexing in a predetermined, predictable manner when a compressive force acts on the assembly from either its distal end or its proximal end. At least one spine has at least one region of greater (or hyper) flexibility that allows the electrode assembly to deform, for example, compress, for absorbing and dampening excessive force that may otherwise cause damage or injury to tissue wall in contact with the assembly, without compromising the structure and stiffness of the remaining regions of the spine, including its distal and proximal regions. The one or more regions of greater flexibility in the spine allow the spine to flex into a generally V-shape configuration or a generally U-shape configuration.