Delivery Catheter Tether System for Kink Resistance
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Solution Overview
Problem
Existing implantable medical device delivery systems face challenges with kink resistance, maneuverability, and accurate deployment, particularly in tortuous vascular pathways, and often require invasive procedures or risk contact damage during deployment.
Innovation Solution
The development of delivery catheters with improved kink resistance and a reduced profile, featuring an outer sheath and/or balloon for secure deployment, along with a tether and inner shaft system that secures the implantable medical device, allowing for precise placement and reduced risk of migration or contact damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a traditional delivery catheter design is used, then the device can be delivered through vasculature, but it suffers from kinking and poor maneuverability in tortuous vascular pathways
Solution Approach 1:
The delivery catheter is divided into multiple segments including a delivery catheter body, an inner shaft, and a tether system. The inner shaft can be independently advanced or retracted relative to the delivery catheter body, allowing the distal portion to be stiffened for stability while the proximal portion remains flexible for maneuverability. This segmentation resolves the contradiction by providing different mechanical properties in different zones of the same device.
Solution Approach 2:
The delivery catheter employs a dynamic inner shaft that can change its stiffness characteristics during delivery. The inner shaft may include a shape memory alloy or other dynamic material that allows it to transition from a flexible state during navigation to a stiffer state for secure device retention. This dynamic property adjustment resolves the contradiction between needing flexibility for maneuverability and stiffness for kink resistance.
2Manufacturing precision
If the implantable medical device is secured to the delivery catheter, then deployment accuracy is improved, but the fixation means may contact and damage the vasculature walls before deployment
Solution Approach 1:
The fixation means (expandable basket or loop) is nested within the delivery catheter body during delivery, with the inner shaft positioned inside the fixation means. This nested configuration keeps the fixation means collapsed and contained, preventing contact with vascular walls. Upon deployment, the inner shaft is retracted, allowing the fixation means to expand in place without having contacted the vasculature during delivery, thus resolving the contradiction between secure positioning and preventing contact damage.
Solution Approach 2:
The delivery system is designed so that the inner shaft is preliminarily positioned to support and constrain the fixation means in a compressed state before deployment. This preliminary positioning ensures the fixation means remains harmlessly contained during navigation through tortuous vasculature, and only expands to contact tissue at the precise moment of intended deployment, resolving the contradiction between early security and late contact.
3Reliability
If an outer sheath and balloon are used for device retention and deployment, then deployment control is improved, but the catheter profile increases and maneuverability decreases
Solution Approach 1:
The invention extracts and eliminates the balloon component from the traditional delivery system, replacing it with a tether system that passes through the delivery catheter and secures the implantable device to the inner shaft. This extraction of the balloon reduces the overall catheter profile and eliminates the complex balloon inflation/deflation mechanism, improving maneuverability while maintaining reliable deployment control through the tether system.
Solution Approach 2:
The tether acts as an intermediary element between the inner shaft and the implantable device, replacing the need for a balloon. The tether can be tensioned to secure the device during delivery and then released to allow deployment, providing reliable control without requiring the bulky balloon structure. This intermediary approach resolves the contradiction by achieving deployment control through a less intrusive mechanism.
Data Source
AI summary
A kit for implantation of an implantable medical device (IMD) comprises an elongated outer shaft, a tether, and an elongated inner shaft. The IMD comprises a fixation element comprising a looped portion. The outer shaft is sized to traverse a vasculature of the patient and defines a longitudinal lumen and a port in fluid communication with the lumen and located proximal a distal end of the outer shaft. A first portion of the tether is configured to pass through the lumen. A second portion of the tether is configured to exit the lumen through the port and pass through the looped portion of the fixation element of the IMD outside of the outer shaft. A third portion of the tether defines a looped portion of the tether. A portion of the inner shaft is configured to pass through the lumen and to pass through the looped portion of the tether.