Expandable Dilator Mechanism for Safe Sheath Withdrawal
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Solution Overview
Problem
Existing medical devices face challenges in withdrawing deflated balloons or large medical devices through unexpanded introducer sheaths without causing deformation or damage, particularly during procedures like transcatheter aortic valve replacement (TAVR) where balloon valvuloplasty (BAV) devices may not deflate properly, leading to issues with introducer sheath deformation.
Innovation Solution
The use of an expandable dilator with a shaft and expander mechanism that includes a tether or flexible ring, which when pulled proximally, expands the introducer sheath by separating slits or unfolding folds, allowing deflated balloons or medical devices to be withdrawn safely.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a deflated balloon or large medical device is withdrawn through an unexpanded introducer sheath, then the device can be removed from the patient, but the sheath may deform or be damaged
Solution Approach 1:
The dilator expands the introducer sheath in advance before device withdrawal, preparing the sheath to accommodate the deflated balloon or large medical device and prevent deformation during removal
Solution Approach 2:
The dilator is divided into functional segments including an expandable expander, tether mechanism, and shaft with cutout, allowing controlled expansion of the sheath through sequential activation of these components
2Adaptability or versatility
If the expander is pulled proximally through the shaft to expand the sheath, then the sheath can accommodate larger devices, but the shaft structure must accommodate the expander movement
Solution Approach 1:
The expander is positioned within the shaft structure and can be pulled through the shaft's lumen, with the shaft containing cutouts that allow the expander to interact with and expand the sheath while remaining protected within the shaft
3Strength
If the expander outer diameter is larger than the lumen inner diameter, then the expander can effectively expand the sheath, but the expander must be precisely positioned and controlled
Solution Approach 1:
The tether acts as an intermediary mechanism connecting the operator's pulling action to the expander, allowing controlled transmission of force to expand the sheath while maintaining precise positioning of the expander within the shaft
Solution Approach 2:
The mechanical connection between the shaft and expander is replaced with a flexible tether connection, allowing the expander to be pulled through the shaft and positioned against the sheath without rigid mechanical constraints
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 dilator effectively expands the introducer sheath, enabling safe withdrawal of medical devices without damaging the sheath, thereby facilitating smooth procedural execution.
Implementation Method 1
pulling the tether proximally moves the expander proximally through the shaft such that the expander separates opposing edges of the slit as the expander moves proximally through the shaft
Implementation Method 2
the flexible ring configured to be moved axially from the tapered distal tip onto the shaft, the flexible ring having a plurality of protrusions extending radially outward
Data Source
AI summary
An expandable dilator for use with an expandable sheath includes a shaft having a tapered distal tip, a body, a proximal end, and a lumen extending longitudinally from the distal tip to the proximal end. The expandable dilator includes an expansion mechanism extending radially outward from the outer surface of the shaft. When the expandable dilator is withdrawn proximally into the expandable sheath, the expansion mechanism engages the distal end of the sheath and expands the sheath as the expansion mechanism moves proximally through the sheath.