Segmented Torque Cable Structure for Predictable Device Deployment
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Solution Overview
Problem
Existing delivery cables for medical devices face challenges in providing sufficient column strength and maneuverability through tortuous anatomy while minimizing bias and snaking during deployment, leading to unpredictable final positions and increased force requirements.
Innovation Solution
A delivery cable design featuring a rigid proximal section and flexible distal section, comprising a flexible inner core, a rigid proximal outer coil, and a flexible distal outer coil with reduced rigidity, to enhance column strength and flexibility, reducing bias and snaking during deployment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the delivery cable is made rigid to provide column strength for advancing the medical device, then the cable can push the device through the catheter, but the cable cannot navigate tortuous anatomy and creates excessive bias on the deployed device
Solution Approach 1:
The delivery cable is divided into multiple sections with different rigidity characteristics: a proximal section with higher rigidity for column strength, a distal section with lower rigidity for navigating tortuous anatomy, and a transition section between them. This segmentation allows each portion to perform its specific function optimally.
Solution Approach 2:
Different sections of the delivery cable are assigned different local qualities (rigidity values) to match their functional requirements. The proximal section has higher rigidity for pushing force, while the distal section has lower rigidity for flexibility in tortuous paths.
2Adaptability or versatility
If the delivery cable is made flexible to navigate tortuous anatomy, then the cable can follow the vasculature path, but the cable lacks sufficient column strength to advance the medical device through the catheter
Solution Approach 1:
The cable is segmented into flexible distal portions for navigating anatomy and a rigid proximal portion for providing column strength during device advancement.
Solution Approach 2:
The cable exhibits spatially varying rigidity properties, with flexible characteristics at the distal end for navigation and rigid characteristics at the proximal end for force transmission.
3Ease of operation
If the distal outer member has a smaller outer diameter to reduce snaking, then the cable advances more smoothly, but the cable lacks sufficient torque transmission capability
Solution Approach 1:
The distal outer member has a locally optimized larger outer diameter in the transition section to reduce snaking during advancement, while maintaining sufficient torque transmission through the structured coil design.
Solution Approach 2:
The distal outer member is constructed as a coil structure that combines flexibility with torque transmission capability, effectively creating a composite mechanical behavior.
Data Source
AI summary
The present disclosure describes delivery cables for delivering a medical device and methods of making and employing the same. In one embodiment, a delivery cable includes a flexible inner core, a proximal outer coil, and a distal outer coil. The proximal outer coil has a first rigidity. The distal outer coil surrounds at least a portion of a distal section of the flexible inner core and has a second rigidity less than the first rigidity thereby, thereby reducing bias placed on the medical device by the delivery cable during deployment of the medical device. Relative dimensions of an outer diameter of the distal outer coil and an inner diameter of a delivery sheath for deploying the delivery cable reduce snaking of the delivery cable within the delivery sheath.