Offset Soft Tip Catheter for Stent Tracking
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Solution Overview
Problem
Catheters face challenges in navigating through vascular systems, particularly when encountering stented segments or tortuous vessels, due to their stiffness and lack of directional control, which can lead to damage or entanglement with existing stents.
Innovation Solution
A catheter with a distal soft tip featuring an offset inner diameter is created by using a mandrel with a curve to produce an asymmetric cross-section, allowing for enhanced directional flexibility and tracking capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the catheter tip is made soft to reduce trauma to vessel wall tissue, then the trauma to tissue is reduced, but the catheter loses directional control and stiffness needed for procedural manipulation
Solution Approach 1:
The catheter employs different material properties at different locations: the distal tip is made of soft material (e.g., polyether block amide) to minimize tissue trauma, while the proximal shaft maintains rigid material (e.g., nitinol) for maneuverability and stiffness. This local differentiation allows each region to optimize its mechanical properties for its specific functional requirements.
Solution Approach 2:
The catheter is constructed as a composite structure combining soft and rigid materials. The distal tip uses soft polyether block amide to reduce trauma, while the proximal portion uses nitinol for stiffness and maneuverability. This composite approach resolves the contradiction by allowing different material types to coexist in a single device, each performing its optimal function.
2Ease of operation
If the catheter tip is tapered to facilitate movement through vessels, then ease of movement is improved, but directional control and tracking ability across stents are compromised
Solution Approach 1:
The catheter tip features an asymmetric cross-sectional geometry where the inner lumen diameter is offset from the outer diameter, creating an eccentric configuration. This asymmetric design provides directional bias that enhances tracking ability across stents while maintaining the tapered shape for ease of movement. The offset creates a preferred direction of flexibility that aids in navigating tortuous vessels and stented segments.
Solution Approach 2:
The catheter tip incorporates curved geometric features including a tapered profile and an offset inner lumen that creates a curved bending characteristic. This curvature design allows the tip to flex in a preferred direction, enhancing its ability to track across stents and navigate tortuous vascular anatomy while maintaining smooth movement through the vessel system.
3Ease of operation
If the catheter is made rigid to provide torsional control and stiffness for manipulation, then procedural control is improved, but the risk of puncturing or damaging vessels increases
Solution Approach 1:
The catheter is divided into distinct segments with different mechanical properties: a proximal rigid shaft portion for manipulation and torsional control, and a distal soft tip portion for trauma-free vessel wall contact. This segmentation allows the rigid and soft characteristics to be separated spatially, with the rigid portion providing procedural control and the soft portion protecting the vessel wall.
Solution Approach 2:
The catheter uses composite material construction combining nitinol (rigid) for the proximal shaft to provide torsional control and maneuverability, and polyether block amide (soft) for the distal tip to minimize vessel damage. This material composite approach allows the device to simultaneously achieve procedural control and tissue safety by assigning different material properties to different functional regions.
4Ease of manufacture
If a symmetric tapered end is used at the catheter tip, then manufacturing simplicity is maintained, but directional benefit when approaching stented sharp turns is lost
Solution Approach 1:
The catheter tip incorporates an asymmetric offset design where the inner lumen diameter is deliberately positioned away from the center of the outer diameter. This asymmetric configuration creates a directional flexibility advantage that enhances the catheter's ability to track across stents and navigate sharp turns, while the overall tapered geometry maintains manufacturing feasibility. The asymmetry is integrated into the molding process, adding directional functionality without substantially complicating manufacturing.
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 offset inner diameter design enables easier navigation through stented segments and eccentric lesions, reducing the risk of damage and improving the catheter's ability to divert away from obstructions, while maintaining sufficient stiffness for procedural control.
Implementation Method 1
Heat is applied. The heat causes the proximal end of the tip and the soft distal end of the tip to become flowable while the heat shrink contracts radially, thereby bonding both segments.
Implementation Method 2
The heat causes the proximal end of the tip and the soft distal end of the tip to become flowable
Data Source
AI summary
A medical catheter device is disclosed that comprises a tubular shaft member, a soft tip member, and a wire guide lumen extending longitudinally within the tubular shaft member and the soft tip member. The wire guide lumen is offset relative to the centerline within the soft tip member. By offsetting the inner diameter of the soft tip member in such a way as to not change the outward profile of the catheter, the soft tip will have improved tracking across existing stents and eccentric lesions.