Slotted Catheter Shaft Flexibility and Diameter Trade-off
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Solution Overview
Problem
Catheters used in medical applications, particularly for navigating tortuous vasculature, face challenges in maintaining flexibility while minimizing size and ensuring structural integrity, as additional materials for flexibility often increase wall thickness and overall diameter.
Innovation Solution
A catheter design featuring a flexible, hollow shaft with a slotted portion having alternating helical patterns of cut and uncut segments, allowing for varying flexibility and stiffness along its length, enabling navigation through multiple bends without kinking or ovalizing, and constructed from materials like stainless steel or nitinol.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If additional materials or materials with different stiffness are used to improve flexibility, then flexibility is improved, but wall thickness and outer diameter increase
Solution Approach 1:
The catheter shaft is segmented into multiple sections with different flexibility characteristics. The distal section has fewer longitudinal slots providing higher flexibility for navigating tortuous vasculature, while the proximal section has more slots providing higher rigidity for stable manipulation. This segmentation allows the catheter to achieve both flexibility and controlled diameter without adding material thickness.
Solution Approach 2:
Different portions of the catheter shaft are given different local properties through varying slot densities. The distal end has lower slot density for enhanced flexibility where it needs to navigate sharp angles, while the proximal end has higher slot density for rigidity where it needs to be manipulated. This local differentiation resolves the contradiction by placing flexibility exactly where needed without increasing overall diameter.
2Ease of operation
If additional materials or materials with different stiffness are used to improve flexibility, then flexibility is improved, but structural integrity deteriorates
Solution Approach 1:
The catheter is divided into segments with different slot configurations. The distal segment has fewer slots maintaining structural integrity for navigating vessels, while the proximal segment has more slots providing flexibility for manipulation. This segmentation allows each region to optimize its properties independently, preserving overall structural integrity while achieving necessary flexibility.
Solution Approach 2:
Local quality variations are achieved through different slot densities in different regions. The proximal region with higher slot density provides flexibility for manipulation, while the distal region with lower slot density maintains structural integrity for navigating tortuous vasculature. This localized property distribution resolves the contradiction between flexibility and structural integrity.
3Volume of moving object
If wall thickness is decreased to reduce outer diameter, then outer diameter is reduced, but structural integrity deteriorates
Solution Approach 1:
The catheter shaft is segmented into regions with different slot densities that compensate for varying wall thickness requirements. The distal section with fewer slots can have thinner walls to reduce diameter, while the proximal section with more slots maintains adequate structural integrity through its rigidity-providing slot configuration. This segmentation allows optimized wall thickness distribution.
Solution Approach 2:
Local quality is optimized by varying slot density along the shaft length. Regions requiring higher flexibility (distal) have fewer slots allowing thinner walls and reduced diameter, while regions requiring rigidity (proximal) have more slots providing structural support. This local optimization resolves the contradiction between reduced diameter and maintained structural integrity.
4Area of stationary object
If inner diameter is increased to facilitate device positioning and aspiration, then inner diameter is increased, but wall thickness must be decreased which compromises structural integrity
Solution Approach 1:
The catheter is segmented into distal and proximal sections with different slot configurations that allow differential wall thickness optimization. The distal section can have thinner walls to maximize inner diameter for device positioning and aspiration, while the proximal section maintains thicker walls with higher slot density to preserve structural integrity. This segmentation enables optimized inner diameter without compromising overall strength.
Solution Approach 2:
Local quality optimization allows the distal region to have thinner walls for increased inner diameter facilitating device positioning and aspiration, while the proximal region maintains thicker walls for structural integrity. The varying slot densities provide the necessary mechanical support at different locations, resolving the contradiction between maximized inner diameter and maintained structural integrity.
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 design enhances flexibility to traverse tight angles while maintaining structural integrity, reducing the catheter's outer diameter and increasing inner diameter, facilitating better device positioning and aspiration within the vasculature.
Implementation Method 1
The slotted portion includes a first segment with a first pattern of slotted openings and a second segment extending proximally relative the first segment with a second pattern of slotted openings different from the first pattern... configured to provide the flexible and hollow shaft with flexibility to traverse at least two bends having angles of at least or up to 90 degrees
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 1E~1G
AI summary
A catheter or shaft, such as a distal access support or aspiration catheter, is provided that is configured to be advanced at least partially within a patient. The catheter or shaft may include a flexible and hollow shaft including a proximal end and a distal end. The flexible and hollow shaft may include a slotted portion with a plurality of slotted openings, the slotted portion including a first segment with a first pattern of slotted openings and a second segment extending proximally relative the first segment with a second pattern of slotted openings different from the first pattern.