Steerable Catheter Whipping Control via Segmented Shaft

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Solution Overview

Problem

Steerable catheters experience whipping issues during rotation, leading to reduced control and accuracy, especially in tortuous vasculature, and existing methods for agent delivery cause mechanical trauma and inaccurate needle placement.

Innovation Solution

The catheter shaft design incorporates incremental whipping features with varying flexural modulus sections to control torque response and improve needle accuracy by relocating the neutral axis of bending, and a pneumatic delivery mechanism replaces needle-based agent delivery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the catheter shaft is made more flexible to enable navigation through tortuous vasculature, then the catheter can reach target sites more effectively, but whipping increases during rotation reducing control accuracy

Engineering Contradiction:

Improvecatheter navigabilityVSAvoidcontrol accuracy

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The catheter shaft is divided into multiple sections with different flexural moduli. The distal section has lower flexural modulus for flexibility and navigability, while the proximal section has higher flexural modulus for stability and reduced whipping during rotation, allowing the catheter to achieve both adaptability and control accuracy

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the catheter shaft are assigned different mechanical properties: the distal portion is made more flexible to navigate tortuous vasculature, while the proximal portion is made stiffer to reduce whipping and improve rotational control, thereby resolving the contradiction between navigability and control accuracy

Inventive Principle:

Principle #3Local quality

2Measurement precision

If the tendon wire is pulled to deflect the distal section toward the target site, then the catheter can be positioned accurately, but the needle position relative to the catheter tip becomes inaccurate due to shaft deformation

Engineering Contradiction:

Improvecatheter tip positioningVSAvoidneedle placement accuracy

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The needle is repositioned from a longitudinal orientation to a transverse orientation relative to the catheter shaft. This dimensional change allows the needle to extend perpendicular to the shaft axis, making the needle tip position independent of shaft deflection and tendon wire tension, thereby maintaining manufacturing precision while achieving accurate catheter tip positioning

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Productivity

If a needle is used to deliver therapeutic agent into the myocardial tissue, then direct delivery is achieved, but mechanical trauma is caused to the tissue

Engineering Contradiction:

Improveagent delivery efficiencyVSAvoidtissue trauma

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The mechanical needle penetration system is replaced with a pneumatic delivery system that uses pressurized gas to propel the therapeutic agent through the catheter wall and into the myocardial tissue. This substitution eliminates the mechanical trauma caused by needle puncture while maintaining efficient agent delivery through the high-velocity jet of therapeutic solution

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Reliability

If the catheter shaft is made stiffer to reduce whipping during rotation, then control accuracy improves, but the catheter cannot navigate through tortuous vasculature effectively

Engineering Contradiction:

Improverotational controlVSAvoidvasculature navigability

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The catheter shaft is segmented into proximal and distal sections with different flexural moduli, allowing the distal section to be flexible for navigating tortuous vasculature while the proximal section remains stiff for maintaining rotational control and reducing whipping during operator manipulation

Inventive Principle:

Principle #1Segmentation

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 design enhances control over catheter tip placement, reduces mechanical trauma during agent delivery, and ensures precise and repeatable needle deployment without the need for needles.

Implementation Method 1

activating a pneumatic source such that the therapeutic agent is propelled out of the tip at a velocity sufficient to deliver the therapeutic agent into the adjacent target tissue

Methodology Applied

Scientific EffectPressurisation: Pressurisation

Data Source

PatentUS8708954B2Agent delivery catheters

Publication Date: 2014.04.29 ABBOTT CARDIOVASCULAR SYSTEMS INC

AI summary

An agent delivery catheter that includes an anti-whipping feature, improved assembly of distal parts and/or accuracy/repeatability of needle delivery to a target tissue. Additional features include fitting a catheter with a pneumatic delivery device for delivery of a therapeutic agent without using a needle.