Expandable Tube Tether Locking for IMD Delivery
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Solution Overview
Problem
Existing implantable medical device delivery systems are prone to inadvertent release due to misalignment of tethering members, which can lead to insecure attachment and entanglement issues during implantation, affecting the precision and reliability of device placement.
Innovation Solution
A delivery system with a catheter shaft and an expandable tube that transitions between a released and locked condition, using a tether with a distal end that changes diameter to secure the tethering member within the tube, preventing misalignment and entanglement, and ensuring secure attachment and detachment of the medical device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two separate tethers connect the IMD to the catheter in the tethered state, then the IMD can be securely attached and tested, but the tethers may become misaligned and entangled, causing inadvertent release
Solution Approach 1:
The patent combines two separate tethers into a single integrated tether structure. The single tether includes a body with a tethering member at one end and a connector at the other end, eliminating the need for two separate tether components and their associated alignment issues.
Solution Approach 2:
The tether is segmented into distinct functional portions: a body portion, a tethering member portion with diameter greater than the hole, and a connector portion. This segmentation allows each portion to perform its specific function while maintaining overall simplicity.
2Reliability
If the tethering members are misaligned during implantation, then inadvertent release may occur, but maintaining precise alignment increases the complexity of the delivery system
Solution Approach 1:
The tethering member has a localized property of having a diameter greater than the hole in the attachment feature, creating a mechanical interference fit that prevents inadvertent release. This local geometric feature provides the necessary security without requiring complex alignment mechanisms throughout the entire tether structure.
3Ease of operation
If the tethers are made to pass through the hole for release, then the IMD can be disconnected, but the tethers may become entangled making transition to released state difficult
Solution Approach 1:
The connector portion of the single tether is designed to be extractable from the catheter assembly independently. The connector can be pulled through the catheter to release the tethering member from the attachment feature, providing a clean disconnection path that avoids entanglement with other catheter components.
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 system prevents unintended release and entanglement, allowing for precise placement and secure attachment of the medical device, enhancing the reliability of the implantation process by maintaining tether alignment and reducing the risk of misalignment-induced detachment.
Implementation Method 1
an expandable distal end portion extending distally beyond the distal end of the catheter shaft... In the released condition, the distal end of the tube has a diameter smaller than the first diameter, and in the locked condition, the distal end of the tube has a diameter larger than the first diameter
Data Source
Figure 1
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Figure 2B
AI summary
An implantable medical device (402) includes an attachment member (424) having an aperture (428) with a first diameter. A delivery device (400) includes a catheter shaft (406), a tube (450') within the shaft, and a tether (422') within the tube. The tube has a main portion (455') with a second diameter and an expandable distal end (457'). The tether has a body (423') and a tether member (426') having a third diameter greater than the second diameter and smaller than the first diameter. The tether is slideable relative to the tube from a released condition in which the tether member is positioned at least partially distal to the distal end of the tube, and a locked condition in which the tether member is at least partially surrounded by the distal end of the tube. The distal end of the tube can pass through the aperture only in the released condition.