Nested Balloon Catheter Shaft for Low-OD Large-Lumen Delivery
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Solution Overview
Problem
Existing microcatheters face challenges in achieving a minimized outer diameter (OD) while maintaining a large inner lumen size and balancing flexibility and torqueability, particularly when incorporating an expandable balloon, which often increases the OD and limits their ability to navigate tortuous vasculature effectively.
Innovation Solution
A balloon catheter design with thin-walled outer and inner shafts, secured at discrete connection points, where the balloon is bonded radially inward to maintain the OD and includes a stiff proximal section for torque transmission and a flexible distal section for navigation, with a dedicated inflation lumen for rapid balloon expansion and deflation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an expandable balloon is incorporated into the catheter, then the catheter can isolate vascular compartments and deliver drugs to target tissue, but the outer diameter increases and the ability to navigate tortuous vasculature is limited
Solution Approach 1:
The balloon is nested within the catheter shaft structure, with the catheter shaft forming a sheath that contains the balloon. The balloon is positioned within the distal portion of the catheter shaft, allowing it to be compact when deflated while still providing isolation function when inflated. This nesting approach minimizes the overall outer diameter of the catheter assembly.
Solution Approach 2:
The catheter shaft is designed with dynamic properties, being more flexible in the distal portion to facilitate navigation through tortuous vasculature while maintaining structural integrity. The shaft can be advanced over a guidewire and manipulated to navigate complex vascular paths, then positioned to provide stable balloon isolation when needed.
2Length of moving object
If the catheter shaft wall thickness is reduced to minimize outer diameter, then the catheter can navigate smaller vessels better, but the structural strength and torque transmission are compromised
Solution Approach 1:
The catheter shaft is segmented into different portions with different mechanical properties. The proximal portion has greater stiffness for torque transmission and manipulation, while the distal portion is more flexible for navigation. This segmentation allows each section to be optimized for its specific function while maintaining overall structural integrity.
Solution Approach 2:
The catheter shaft is constructed from composite materials or multi-layer structures that combine different material properties. The shaft includes a flexible polymer outer layer for navigation and a reinforcing inner layer (such as a braid or mesh) that provides strength and torque transmission capability, achieving both flexibility and structural integrity.
3Productivity
If the inner lumen size is increased to improve drug delivery capacity, then more drug can be delivered simultaneously, but the outer diameter increases and navigation ability is reduced
Solution Approach 1:
The catheter employs a multi-lumen configuration where multiple functions are integrated into different spatial dimensions within the shaft. The drug delivery lumen is positioned concentrically within the shaft, while the balloon inflation lumen is formed in the annular space between the inner and outer shafts. This dimensional arrangement allows large drug delivery capacity without proportionally increasing the outer diameter.
Solution Approach 2:
The catheter shaft structure serves multiple functions simultaneously: it provides structural support, contains the balloon, provides drug delivery pathways, and allows for manipulation and navigation. The multi-lumen design enables the same shaft structure to handle drug delivery, balloon inflation, and mechanical manipulation without requiring separate components that would increase overall diameter.
4Ease of operation
If the distal section is made more flexible for navigation through tortuous vasculature, then the catheter can navigate better, but the torque transmission to the balloon is reduced
Solution Approach 1:
The catheter is segmented into a proximal section with higher stiffness for torque transmission and manipulation, and a distal section with higher flexibility for navigation. The shaft includes a transition zone that gradually transitions from stiff to flexible, allowing torque to be transmitted through the proximal portion while the distal portion can navigate tortuous vasculature without excessive resistance.
Solution Approach 2:
Different portions of the catheter shaft have different mechanical properties tailored to their specific functions. The proximal portion has greater rigidity for manipulation and torque transmission, while the distal portion has greater flexibility for navigation. This local differentiation of mechanical properties allows the catheter to simultaneously achieve good navigation and effective torque transmission.
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 allows for increased inner lumen size, minimized OD, and effective navigation through tortuous vasculature with rapid drug delivery and balloon inflation/deflation, enhancing the efficacy of transvascular procedures.
Implementation Method 1
fluid to be advanced through the inflation lumen and into an internal volume of the balloon to inflate the balloon
Implementation Method 2
a proximal collar radially outside of the proximal end of the balloon, the proximal collar compressing the proximal end of the balloon between the proximal collar and the outer surface of the distal region of the adapter
Implementation Method 3
a stiff proximal section for torque transmission
Data Source
AI summary
Balloon catheters that includes inner and outer elongate shafts, each of which is secured relative to an end of an inflatable member. The inner and outer elongate shafts are secured relative to one another at one more discrete connection locations. The balloon bonding locations are disposed radially inward relative to an outer dimension of the outer elongate shaft.