Nested Balloon Catheter Shafts for Low-Profile Drug Delivery
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Solution Overview
Problem
Existing catheters face challenges in achieving a minimized outer diameter while maintaining a large inner lumen size and ensuring both trackability and torqueability, particularly when incorporating an expandable balloon, which often increases the outer diameter and compromises flexibility and torque transmission.
Innovation Solution
A balloon catheter design with thin-walled outer and inner shafts, where the balloon is secured radially inward to maintain the outer diameter, and a stiff proximal section transfers torque to a flexible distal section, with discrete connection points to resist movement and allow for balloon inflation through a separate lumen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an expandable balloon is incorporated into the catheter, then the catheter can perform embolization and drug delivery functions, but the outer diameter increases which compromises trackability through small vessels
Solution Approach 1:
The balloon is nested within the catheter shaft structure, specifically positioned within the distal section of the outer shaft. The balloon is secured to the inner shaft using a bonding agent, allowing it to be contained within the catheter's outer diameter envelope while maintaining its expandable functionality for embolization and drug delivery procedures.
2Length of moving object
If the wall thickness of the shaft is reduced to minimize outer diameter, then trackability improves, but torque transmission capability deteriorates
Solution Approach 1:
The catheter shaft is divided into distinct sections with different mechanical properties. The proximal section has greater stiffness to provide torque transmission capability, while the distal section has reduced stiffness to maintain flexibility and trackability. This segmentation allows each region to be optimized for its specific functional requirements without compromising the entire structure.
Solution Approach 2:
Different regions of the catheter shaft are assigned different mechanical properties. The proximal section uses materials or structures with higher stiffness for torque transmission, while the distal section uses materials or structures with lower stiffness for flexibility. This local differentiation of mechanical properties resolves the contradiction between wall thickness, trackability, and torque transmission.
3Productivity
If the central lumen size is increased to facilitate drug delivery, then delivery efficiency improves, but the outer diameter increases which compromises trackability
Solution Approach 1:
The catheter employs multiple lumens arranged in a segmented configuration. A first lumen is positioned within the inner shaft for drug delivery, while a second lumen is positioned within the outer shaft for balloon inflation. This segmentation allows the drug delivery lumen to have adequate size for efficient drug delivery without requiring the entire catheter outer diameter to be large, as the balloon inflation lumen utilizes the space between the inner and outer shafts.
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 achieves a minimized outer diameter with a larger inner lumen, enabling effective tracking through tortuous vasculature and rapid drug delivery while maintaining torque transmission and balloon inflation capabilities.
Implementation Method 1
A lumen passes through the catheter and exits within the intra-balloon space allowing injection of drugs, emulsions, fluids and fluid/solid mixtures
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
the distal end of the inflatable balloon having an inner surface that is disposed radially inward relative to the outer surface of the distal end of the outer elongate shaft
Data Source
AI summary
Catheters that includes inner and outer elongate shafts, each of which is secured relative to an end of an inflatable member. Balloon bonding locations may be disposed radially inward relative to an outer dimension of the outer elongate shaft.