Swaged Coaxial Torque Shaft for Precise Biostimulator Delivery
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Solution Overview
Problem
Existing transport systems for leadless cardiac pacemakers suffer from inefficient torque transmission, leading to wind up and unloading issues, which result in poor correspondence between the input and output rotations, affecting the delivery and retrieval efficiency.
Innovation Solution
A biostimulator transport system with a swaged torque shaft featuring a dual-layer, coaxial construction, where the outer cable is swaged over the inner coil, forming a friction or slip fit, to enhance torque transmission and reduce wind up, ensuring a direct correlation between input and output rotations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an elongated cable is used as the torque transmission component, then the device can transmit torque, but the torque transmission efficiency is reduced due to wind up and unloading
Solution Approach 1:
The torque shaft is divided into multiple discrete segments or sections along its length. Each segment can be independently swaged or crimped to the outer cable, allowing for distributed torque transmission and reducing the wind-up effect that occurs in continuous flexible cables. This segmentation maintains torque efficiency while preserving the needed flexibility.
Solution Approach 2:
The torque shaft employs a nested construction where an inner core element is surrounded by an outer cable that is swaged or crimped around it. This nested structure allows the inner core to provide structural integrity and torque transmission while the outer cable provides flexibility and protection, eliminating the wind-up problem of single-cable designs.
2Adaptability or versatility
If the torque transmission component is made rotationally soft, then flexibility is improved, but correspondence between input and output rotation is degraded
Solution Approach 1:
Different sections of the torque shaft have different structural properties. The regions where swaging or crimping is applied provide rigid torque transmission with high rotational correspondence, while intermediate sections maintain flexibility. This local differentiation of properties allows the shaft to be both flexible and precise in different locations along its length.
Solution Approach 2:
The torque shaft combines materials and structures with different mechanical properties - a rigid inner core for torque transmission surrounded by a flexible outer cable. This composite construction provides both the flexibility needed for navigation and the rotational precision needed for accurate anchor deployment, resolving the contradiction between softness and correspondence.
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 swaged torque shaft improves torque transmission efficiency, reducing wind up and unloading, allowing for precise and effective delivery and retrieval of leadless pacemakers, even under challenging conditions.
Implementation Method 1
The outer cable is swaged over the inner coil, forming a friction or slip fit, to enhance torque transmission
Data Source
AI summary
A biostimulator transport system, such as a biostimulator delivery system, having a swaged torque shaft, is described. The torque shaft includes an outer cable coaxially arranged with an inner coil. The inner coil has a single wire coil extending around a central axis in a first helical direction, and the outer cable has several outer strands that extend around the central axis in a second helical direction that is different than the first helical direction. The outer cable can be swaged to form a close fit to the inner coil. The close fit of the swaged coaxial torque shaft structure can track to a target site through tortuous vessels and efficiently transfer torque from a handle to a docking cap of the biostimulator transport system to drive a biostimulator into the target site. Other embodiments are also described and claimed.