Expandable Sheath Reducing Insertion Force and Vessel Trauma
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Solution Overview
Problem
Conventional introducer sheaths for endovascular delivery systems pose challenges due to their large profile, which can cause vessel trauma, increase procedure time, and risk of vessel tears and plaque dislodgement during the insertion of prosthetic devices like heart valves.
Innovation Solution
An expandable sheath with a polymer layer composition that allows reversible expansion to accommodate the delivery system, reducing insertion force and minimizing vessel trauma, featuring a polyether block amide or polyurethane-based material with inorganic fillers and solid lubricants for reduced friction and improved flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional introducer sheath with large diameter is used to accommodate the delivery system, then the delivery system can be introduced, but vessel trauma, risk of vessel tears and plaque dislodgement increases
Solution Approach 1:
The sheath transitions from a small compressed diameter for insertion to a large expanded diameter for device delivery, then returns to small diameter for removal. This dynamic size change allows the sheath to accommodate the delivery system while maintaining a small profile during vessel insertion, thereby reducing vessel trauma and the risk of vessel tears and plaque dislodgement.
Solution Approach 2:
The delivery system is nested within the expandable sheath during the procedure. The sheath encompasses the delivery system when expanded, providing protection and support, while maintaining a compact form factor during insertion and removal phases.
2Ease of operation
If multiple dilators or sheaths are used to dilate the vessel progressively, then the vessel can be accessed, but the procedure time increases
Solution Approach 1:
The sheath is divided into different sections with distinct functions: a distal expandable section for accommodating the delivery system and a proximal section for insertion and sealing. This segmentation allows the sheath to perform multiple functions (insertion, expansion, device delivery, removal) in a single device, eliminating the need for multiple sequential dilators and sheaths.
Solution Approach 2:
The expandable sheath serves multiple functions: it acts as an introducer for vessel access, expands to accommodate the delivery system, provides sealing at the insertion site, and facilitates device removal. This multi-functionality consolidates what would traditionally require multiple separate devices into a single universal sheath, reducing procedure time.
3Ease of operation
If a conventional loader extends from the proximal end of the introducer sheath, then the delivery apparatus can be introduced, but the available working length of the delivery apparatus decreases
Solution Approach 1:
The sheath transitions from a compressed state during insertion to an expanded state during device delivery. This dynamic expansion creates the necessary clearance and space for the delivery apparatus within the sheath lumen, eliminating the need for a proximal loader extension while maintaining adequate working length for the delivery system.
4Force
If the sheath is made with reversible expansion capability, then insertion force is reduced, but the sheath structure becomes more complex
Solution Approach 1:
The sheath incorporates a flexible expandable section with circumferential folds that allow reversible expansion and compression. This flexible shell structure enables the sheath to expand to reduce insertion force and friction during device delivery, then compress back to a small diameter for easy removal, without requiring complex mechanical mechanisms.
Solution Approach 2:
The sheath utilizes changes in its physical parameters (diameter, flexibility, wall thickness) along its length and during operation. The expandable section has varying wall thickness and flexibility characteristics that enable controlled expansion and compression, reducing insertion force while managing structural complexity through material and geometric design.
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 expandable sheath reduces insertion force by up to 50% and minimizes vessel trauma and plaque dislodgement, enabling safer and more efficient delivery of prosthetic devices with a single sheath size, thereby shortening procedure time and enhancing patient safety.
Implementation Method 1
the elongated tube is configured to reversibly expand from an initial diameter do in an unexpended position to an expanded diameter de in an expanded position upon passage of a medical device
Implementation Method 2
up to about 20% of a solid lubricant filler based on a total weight of the first compound composition
Data Source
AI summary
Aspects of an expandable sheath can be used in conjunction with a catheter assembly to introduce a prosthetic device, such as a heart valve, into a patient. Such aspects can minimize trauma to the vessel by allowing for temporary expansion of a portion of the introducer sheath to accommodate the delivery apparatus, followed by a return to the original diameter once the prosthetic device passes through. Some aspects can include various configurations of the sheath that comprise an elongated tube having a disclosed composition that can form an outer jacket or a strain relief jacket or can be used as the outer layer of the sheath. Aspects of the present expandable sheath can avoid the need for multiple insertions for the dilation of the vessel and reduce the push force needed for passage of the medical device, thus offering advantages over prior art introducer sheaths.