Variable Stiffness Dilator for Tortuous Vessel Navigation
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Solution Overview
Problem
Current dilators used for accessing blood vessels are either too rigid for initial access or too flexible for navigating tortuous anatomy, necessitating replacement with a more flexible catheter, which complicates procedures like angioplasty and stenting.
Innovation Solution
A dilator with multiple stiffness sections, manufactured from varying material blends such as polypropylene and elastomer, featuring a distal end that tapers and becomes less rigid, allowing for flexibility while maintaining rigidity for sheath advancement, and optionally including an atraumatic tip and radiopaque markers for visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a uniform rigid dilator is used for initial access, then the dilator can effectively dilate the vessel opening, but it cannot navigate tortuous anatomy and causes trauma
Solution Approach 1:
The dilator is divided into multiple sections with different stiffness characteristics. The proximal section maintains rigidity for effective vessel dilation, while the distal section becomes progressively more flexible to navigate tortuous anatomy. This segmentation allows the single dilator to perform both functions that previously required separate devices.
Solution Approach 2:
Different sections of the dilator are constructed with varying material properties to provide localized characteristics. The proximal portion uses stiffer materials for structural support and dilation effectiveness, while the distal portion uses more flexible materials to conform to curved vascular paths, reducing trauma during navigation.
2Ease of operation
If a flexible catheter is used to navigate tortuous anatomy, then the catheter can track through curved vessels, but it lacks the rigidity needed for effective sheath advancement
Solution Approach 1:
The dilator combines flexible distal sections for tracking with a rigid proximal section for advancement. This segmentation enables the device to first navigate curved anatomy using its flexible tip, then provide sufficient structural support in the proximal section to effectively advance the sheath assembly through the vessel.
Solution Approach 2:
The dilator employs composite construction with materials of varying stiffness properties integrated along its length. This allows the device to exhibit both flexibility where needed for navigation and rigidity where needed for mechanical advancement, combining properties that would otherwise require separate devices.
3Strength
If a rigid dilator is used for sheath advancement, then the dilator can effectively support the sheath assembly, but it causes trauma to the vessel wall
Solution Approach 1:
The dilator provides rigidity locally in the proximal section where structural support is needed for sheath advancement, while the distal section transitions to flexible materials that can conform to the vessel wall without causing trauma. This localized differentiation of mechanical properties eliminates the trauma issue while maintaining support capability.
Solution Approach 2:
By segmenting the dilator into rigid and flexible zones, the design allows the rigid proximal portion to bear the mechanical load of advancing the sheath assembly, while the flexible distal portion interfaces gently with the vessel wall, preventing trauma during navigation and deployment.
4Reliability
If multiple separate devices are used (rigid dilator then flexible catheter), then each device can perform its specific function, but the procedure becomes more complex and time-consuming
Solution Approach 1:
The invention merges the functions of multiple separate devices (rigid dilator and flexible catheter) into a single integrated dilator. The combined device maintains the functional performance of both components through its segmented construction, eliminating the need for device replacement and simplifying the procedural workflow.
Solution Approach 2:
The multi-section dilator serves multiple functions within a single device: it navigates tortuous anatomy like a flexible catheter, advances the sheath assembly with rigid support, and reduces vascular trauma. This multi-functionality eliminates the need for multiple specialized devices and reduces procedural complexity.
Data Source
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AI summary
The present invention relates to a dilator (30). The dilator includes a shaft (32), a lumen (41) and a hub (43). The shaft has at least two stiffness sections with the stiffness sections becoming less rigid as they approach a distal end of the shaft. The varying stiffness sections allow the dilator to track along the guidewire through torturous vasculature so as the dilator is advanced and the stiffness is changed, the stiffer sheath can advance smoothly through a blood vessel. The dilator may also taper at the distal tip to stretch the initial skin puncture hole larger to accommodate the dilator shaft and ease the sheath tip insertion through to the vasculature. Or the shaft may taper from where it extends beyond the sheath distal tip to the distal end so that it can reach further distal in the vasculature. The dilator may also include an atraumatic tip for easier advancement of the dilator. The dilator distal end may also include one or more radiopaque markers and a shaped distal end.