Helical Fixation Member with Chisel Tip for Cardiac Leads

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Solution Overview

Problem

Existing implantable medical leads face challenges in securely fixing to cardiac tissue, particularly in areas with hard or fibrotic tissue and non-perpendicular orientations, where traditional screw-in attachments are impractical due to the dynamic and tortuous nature of cardiac structures.

Innovation Solution

A helical fixation member with a 'chisel-tip' design, featuring a tip surface that faces the center axis, allowing for effective piercing and fixation at desired implant sites, including those parallel to the lead's axis, and capable of penetrating through hard fibrotic tissue.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a traditional screw-in attachment is used, then fixation is achieved in perpendicular orientations, but it becomes impractical in hard or fibrotic tissue and non-perpendicular orientations

Engineering Contradiction:

Improvefixation securityVSAvoidadaptability to different tissue orientations and hardness

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent inverts the traditional screw-in approach by using a helical fixation member that advances along the lead axis rather than perpendicular to it. The tip is configured to pierce tissue in the direction of lead advancement, enabling fixation in non-perpendicular orientations and hard or fibrotic tissue where traditional methods fail.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the geometric parameters of the fixation mechanism by using a helical configuration with a specific pitch and diameter ratio. The tip angle and surface orientation are optimized to facilitate piercing along the lead axis, allowing the device to adapt to various tissue types and orientations while maintaining reliable fixation.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If a helical fixation member with a tip facing the center axis is used, then penetration into hard fibrotic tissue is facilitated, but device complexity increases

Engineering Contradiction:

Improveease of penetration into tissueVSAvoidcomplexity of helical structure with oriented tip

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent merges the helical fixation member and the oriented tip into a single integrated structure. The tip is formed as an integral part of the helical member, with the first surface of the tip facing the center axis to facilitate piercing. This integration simplifies manufacturing compared to assembling separate components while maintaining the ability to penetrate hard fibrotic tissue effectively.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS7657325B2Implantable medical lead including a helical fixation member

Publication Date: 2010.02.02 MEDTRONIC INC

AI summary

An implantable medical lead comprises an elongated body extending between a proximal end and a distal end, and a helical fixation member extending from the distal end of the elongated body. The helical fixation member is configured to fix the implantable medical lead at an implant site and includes a tip comprising a first surface generally facing a center axis of the helical fixation member.