Expandable Access Sheath for Repositioning Implanted Medical Devices

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Solution Overview

Problem

Medical devices without stylet or guidewire lumens face challenges in re-gaining venous access for repositioning after implantation, as they lack a mechanism to accommodate devices with larger diameters, such as connectors and anchoring sleeves, making it difficult to reinsert a delivery catheter for repositioning or re-fixation.

Innovation Solution

The development of an access sheath with expandable edges and a tapered design allows for the insertion and accommodation of medical device bodies with larger diameters, enabling re-gaining venous access without the need for additional lumens, using biocompatible materials like polyethylene or PTFE, and incorporating features like interlocking edges and radiopaque markers for visibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a delivery catheter is removed after device implantation, then the device can be fixed at the target site, but venous access is lost and cannot be regained for repositioning

Engineering Contradiction:

Improvedevice fixationVSAvoidrepositioning access

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The access sheath is divided into separate functional sections: a distal section with edges for engaging the device body and a proximal section for operator manipulation. This segmentation allows the sheath to perform multiple functions - maintaining access while allowing device removal and potential repositioning.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The access sheath acts as an intermediary device that remains in the venous system after the delivery catheter is removed. It provides a continuous pathway for guidewires and allows reinsertion of delivery catheters if repositioning is needed, without requiring additional venous punctures.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If the access sheath has a small diameter to minimize trauma, then blood loss is reduced, but devices with larger diameters cannot be inserted

Engineering Contradiction:

Improveblood lossVSAvoiddevice accommodation

Core Design Contradiction:

Object-affected harmful factorsVSAdaptability or versatility

Solution Approach 1:

The access sheath edges are designed to be dynamically adjustable - they can be spread apart to accommodate devices of various diameters and then return to a closed position. This dynamic behavior allows the sheath to adapt to different device sizes while maintaining a compact profile when not in use.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The sheath transitions between different states: the edges can change from a closed configuration (minimizing diameter and blood loss) to an open configuration (accommodating larger devices). This parameter change allows the sheath to resolve the contradiction between size and adaptability.

Inventive Principle:

Principle #35Parameter changes

3Strength

If the access sheath edges are made rigid to maintain structure, then the sheath holds its shape, but friction and trauma to the device body increase

Engineering Contradiction:

Improvesheath structureVSAvoidfriction

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

Different portions of the access sheath have different mechanical properties. The edges are designed with specific structural characteristics for engagement, while the main body of the sheath has smoother, more compliant characteristics to reduce friction as devices pass through during insertion and removal.

Inventive Principle:

Principle #3Local quality

4Ease of operation

If the access sheath remains in the venous system permanently, then continuous access is maintained, but it occupies space and may interfere with device function

Engineering Contradiction:

Improvecontinuous accessVSAvoidvenous space occupation

Core Design Contradiction:

Ease of operationVSArea of stationary object

Solution Approach 1:

The access sheath is constructed as a thin-walled, flexible structure that can collapse or conform to the surrounding venous anatomy. This minimizes the space it occupies while maintaining its function as an access pathway. The sheath can be compressed against the vein wall, reducing its cross-sectional area in the venous system.

Inventive Principle:

Principle #30Flexible shells and thin films

Data Source

PatentUS9302078B2Systems and methods for gaining access around an implanted medical device

Publication Date: 2016.04.05 MEDTRONIC INC

AI summary

Systems for gaining access into a body of a patient around an implanted body of an elongate medical device include a sheath having a deformable wall that allows insertion of the device body into a lumen surrounded by the sheath wall. The sheath wall may include first and second edges that extend from a proximal end to a distal end of the lumen, or just extend along a distal portion of the lumen. A tool, which includes a groove sized to grasp about a circumference of the device body, may facilitate insertion of the device body into the lumen of those sheath embodiments that include the first and second edges, by spreading at least one of the first and second edges of the wall apart from the other of the first and second edges while the device body is grasped within the tool.