Expandable Sheath Assembly with Segmented Proximal and Distal Sheaths
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Solution Overview
Problem
Existing expandable sheath assemblies for percutaneous medical device insertion into body vessels are prone to causing trauma and complications due to their large size, which can lead to vessel tearing, calcification dislodgment, and lack of tactile feedback during insertion.
Innovation Solution
An expandable sheath assembly with a low-profile dilator, a distal sheath made of low-friction polymeric material, and a hemostatic valve that allows the proximal sheath to slide and lift the distal sheath for expansion within the body vessel, reducing the need to push past calcifications and providing tactile feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a larger introducer sheath is used to access body vessels, then the medical device can be introduced, but it creates sizeable arteriotomies causing more trauma to the patient and increases the risk of vessel tearing and calcification dislodgment
Solution Approach 1:
The sheath assembly is divided into multiple segments: a proximal sheath, a distal sheath, and an intermediate dilator. The proximal sheath can be advanced independently through the hub, and the distal sheath is pulled away from the dilator to expand the vessel. This segmentation allows the sheath to be introduced in a compressed state and then expanded locally at the distal end, reducing overall trauma to the vessel.
Solution Approach 2:
The sheath assembly transitions from a compressed, low-profile state during insertion to an expanded state at the distal end. The distal sheath is pulled away from the dilator during the procedure, dynamically changing the configuration from a single compressed unit to a separated expanded structure. This dynamic transformation allows the sheath to accommodate larger medical devices while minimizing initial trauma.
2Adaptability or versatility
If a radially expanding intravascular sheath assembly is used to access the body vessel, then the vessel can be dilated, but the complex mechanisms such as ratcheting or balloon mechanisms increase device complexity and do not provide tactile feedback
Solution Approach 1:
The complex ratcheting or balloon mechanisms found in prior art are extracted and replaced with a simpler pull-away mechanism. The distal sheath is pulled away from the dilator using a wire, eliminating the need for complex expansion mechanisms. This simplification reduces device complexity while maintaining the ability to dilate the vessel effectively.
Solution Approach 2:
The expansion mechanism is simplified to a self-service approach where the distal sheath is pulled away from the dilator by the operator using a wire. This direct manual manipulation provides tactile feedback to the operator during the expansion process, eliminating the need for complex automated or mechanical expansion systems.
3Length of moving object
If the proximal sheath is advanced through the hub to expand the distal sheath, then the vessel can be accessed with a smaller initial profile, but the forces required to insert the sheath may be higher and risk dislodging calcification
Solution Approach 1:
The sheath assembly is segmented into proximal and distal portions that can be advanced independently. The proximal sheath is advanced through the hub first, and then the distal sheath is pulled away from the dilator. This segmentation allows the sheath to be introduced in a compressed state with lower insertion forces, reducing the risk of dislodging calcification while still achieving the necessary expansion.
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 minimizes trauma by reducing shear, hoop, and axial stress on the vessel, lowering the risk of re-access complications and allowing for a smaller initial profile with reduced risk of clotting and vessel damage.
Implementation Method 1
The proximal sheath concurrently slides with the hemostatic valve along the axis A to advance the proximal sheath through the hub and interleave the proximal sheath between the dilator and the distal sheath. As a result, the distal sheath is lifted from the dilator by way of the proximal sheath to effectuate an expansion of the distal sheath within the body vessel.
Implementation Method 2
A distal sheath comprised of a low friction polymeric material overlays the dilator
Data Source
AI summary
An expandable sheath assembly includes a support body extending from a proximal end to a distal end. A guide rod is interconnected to the support body and extends between the ends along an axis. A dilator extends from the guide rod for insertion into a body vessel, and a hub is releasable connected to the distal end of the support body. A distal sheath overlays the dilator, and a hemostatic valve is slidably disposed along the axis. A proximal sheath extends from the hemostatic valve and is disposed in surrounding and coaxial relationship with the guide rod. The proximal sheath is concurrently slidable with the hemostatic valve along axis to advance the proximal sheath through the hub and interleave the proximal sheath between the dilator and the distal sheath for lifting the distal sheath from the dilator and effectuating an expansion of the body vessel.