Catheter Tip Spring Element Flexibility Rigidity

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Solution Overview

Problem

Current endovascular catheter tips face challenges in achieving both longitudinal flexibility and radial rigidity, which are essential for navigating tortuous vessels and avoiding obstacles like stents and vessel lesions, as they require conflicting material properties that are difficult to optimize simultaneously.

Innovation Solution

A catheter tip design featuring a spring-like structure with a tapered external diameter and constant or minimally tapering internal diameter, combined with a radially rigid and tapered distal end, provides both longitudinal flexibility and pushability, minimizing the risk of catching on vessel surfaces or stent struts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the catheter tip is made with a thin or flexible material to achieve longitudinal flexibility, then the catheter can navigate tortuous vessels, but the pushability and radial rigidity are compromised

Engineering Contradiction:

Improvelongitudinal flexibilityVSAvoidpushability and radial rigidity

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The catheter tip is constructed using a composite structure combining a flexible polymer material (e.g., polyurethane or Pebax) with an embedded spring element made of shape memory alloy (Nitinol) or stainless steel. This composite construction allows the tip to exhibit both longitudinal flexibility for navigating tortuous vessels and radial rigidity for maintaining pushability and avoiding collapse when encountering obstacles.

Inventive Principle:

Principle #40Composite materials

2Strength

If the catheter tip is made with a thick or stiff material to achieve pushability and radial rigidity, then the catheter can maintain structural integrity, but the longitudinal flexibility and deliverability are compromised

Engineering Contradiction:

Improvepushability and radial rigidityVSAvoidlongitudinal flexibility

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The catheter tip is segmented into distinct functional zones: a proximal portion with higher radial rigidity for pushability, a distal portion with enhanced longitudinal flexibility for navigation, and a tapered distal edge for reduced catching. The spring element is positioned to provide radial support while the tapered geometry allows the tip to flex longitudinally without collapsing, resolving the contradiction between strength and adaptability.

Inventive Principle:

Principle #1Segmentation

3Stability of the object's composition

If the catheter tip is designed to be radially rigid to avoid collapse, then the distal edge maintains structural integrity, but the tip may flare and catch on vessel surfaces or stent struts

Engineering Contradiction:

Improveradial rigidityVSAvoidcatching on vessel surface or stent struts

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The catheter tip employs local quality variations through its geometry and material distribution. The distal edge is tapered to a smaller radius, creating a smooth, low-profile leading edge that reduces catching on vessel surfaces and stent struts. The spring element provides localized radial rigidity support while the tapered geometry allows controlled flexibility at the critical distal edge, preventing flaring and catching.

Inventive Principle:

Principle #3Local quality

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

This design enhances deliverability and minimizes the risk of kinking or collapse, allowing for smoother navigation through challenging vascular anatomies while maintaining pushability and radial support, thereby improving the overall effectiveness of stent delivery and angioplasty procedures.

Implementation Method 1

a spring-like structure, a spring element, that endows the catheter tip with the desired longitudinal flexibility and pushability

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

The spring element may have an external diameter that tapers distally, i.e., the diameter decreases from the proximal end to the distal end

Methodology Applied

Scientific EffectSpring: Spring

Data Source

PatentUS11458284B2Catheter tip assembled with a spring

Publication Date: 2022.10.04 MEDINOL LTD

AI summary

A catheter tip having a spring element that imparts longitudinal flexibility, pushability and radial rigidity to the catheter tip, thereby improving deliverability, is provided. The spring element also provides radial support to the distal edge of the catheter tip. The spring element may taper distally, but may have a substantially constant inner luminal diameter. The spring element may be partially covered or embedded, leaving its distal end exposed. The spring element may also include spaced coils in a proximal region. The apparatus may be used with any interventional catheter system, but is particularly suitable for use with balloon-expandable stent systems and balloon-angioplasty systems, where flexibility of the catheter tip and minimal flaring of the distal edge of the catheter tip is desirable.