Spring-Biased Tethering Cap for Catheter Navigation
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Solution Overview
Problem
Operators face difficulty navigating catheter assemblies to implant sites on the left side of the heart, such as within the coronary vein or left atrium, due to mechanical and MRI compatibility issues with traditional elongate lead wires.
Innovation Solution
A compact implantable medical device and catheter assembly with an end-cap subassembly featuring a cap and spring-biased tethering member, including a super-elastic wire, which facilitates navigation through blood vessels and orifices by allowing the cap to be positioned in both closed and open configurations, enabling easier passage and deployment of the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a traditional catheter assembly with elongate lead wires is used, then the device can be implanted in subcutaneous pockets, but mechanical and MRI compatibility issues arise and navigation to left side of heart is difficult
Solution Approach 1:
The catheter assembly is divided into distinct functional segments: a delivery catheter for navigation, a compact implantable device, and an end-cap subassembly with tethering member. This segmentation allows each component to be optimized independently - the delivery catheter for navigation ease and the implantable device for mechanical/MRI compatibility.
Solution Approach 2:
The traditional elongate lead wires are extracted and replaced with a compact implantable device that is wholly contained within a relatively compact package. This eliminates the mechanical and MRI compatibility issues associated with traditional lead wires while maintaining the essential pacing function.
2Reliability
If a compact implantable device is used, then mechanical and MRI compatibility is improved, but navigation through tight spaces like coronary sinus ostium becomes more difficult
Solution Approach 1:
The end-cap subassembly incorporates a spring-biased tethering member that can dynamically change the configuration of the cap between compressed and extended states. This dynamic capability allows the cap to adapt to different spatial constraints during navigation through tight spaces like the coronary sinus ostium.
Solution Approach 2:
The tethering member utilizes super-elastic material properties that allow significant deformation and recovery. This parameter change in the material's physical state enables the cap to be compressed into a small profile for navigation, then return to its extended configuration for proper device deployment and function.
3Ease of operation
If the cap is made large enough to facilitate navigation, then ease of navigation improves, but the device size increases and may not fit within the catheter lumen
Solution Approach 1:
The cap's size is made dynamic through the spring-biased tethering member mechanism. During navigation, the cap is compressed to a small volume that fits within the catheter lumen. Once positioned, the tethering member extends, causing the cap to expand to a larger configuration that facilitates device deployment and maintains proper positioning.
Solution Approach 2:
The cap is designed to nest within itself or within the catheter assembly during the delivery phase. The tethering member allows the cap to be collapsed or folded into a compact form that can be passed through the catheter lumen, then deployed outward at the target site for its full navigational and deployment function.
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 end-cap subassembly enhances the ability to deliver the implantable medical device to the left side of the heart by providing a tapered leading edge and spring-biased mechanism, improving navigation and deployment efficiency, particularly through tight spaces like the coronary sinus ostium or interatrial septum.
Implementation Method 1
the spring-biased tethering member of the end-cap subassembly is made, at least in part, from a super-elastic wire having a curvature formed therein
Data Source
AI summary
A catheter assembly includes a cap and a spring-biased tethering member coupled thereto. The cap includes first and second portions, and a transition zone extending therebetween. A girth of the first portion is sized to fit within a distal-most opening of the catheter assembly; and a girth of the second portion tapers from a first size at the transition zone, which is too large to fit within the distal-most opening, to a smaller size at a distal end of the cap. The spring-biased tethering member holds the cap in open and closed positions, when the cap first portion extends within the distal-most opening, and when the cap is separated from the distal-most opening, respectively. At the closed position, the first portion is approximately concentric with the distal-most opening, and at the open position, an entirety of the cap is laterally offset from the distal-most opening.