Rotatable Curve Active Fixation Lead for Cardiac Rhythm Management
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Solution Overview
Problem
Existing implantable medical leads face challenges in maintaining a preformed curved shape during deployment and fixation in the heart, which can lead to stress on the lead and require excessive tissue penetration for anchoring, compromising the accuracy and stability of cardiac rhythm management devices.
Innovation Solution
The design incorporates an outer tubular portion with a bias to maintain a curved shape, an inner tubular portion with a steeper filar pitch and polymer jacket slots for flexibility, and an active fixation mechanism that rotates relative to the outer tubular portion to securely affix to tissue while minimizing stress and maintaining the curved shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the lead uses a preformed curved shape to navigate cardiac anatomy, then the lead can be deployed through venous access, but the lead experiences stress during deployment and fixation that can compromise its structural integrity
Solution Approach 1:
The lead is divided into two distinct tubular portions: an outer tubular portion that maintains the preformed curved shape, and an inner tubular portion that is straight and rotatable within the outer portion. This segmentation allows the outer portion to navigate cardiac anatomy while the inner portion remains stress-free during deployment and fixation.
Solution Approach 2:
The inner tubular portion is nested within the outer tubular portion, with the inner portion capable of rotating relative to the outer portion. The inner coil conductor is surrounded by an inner polymer jacket, which is in turn surrounded by the outer tubular portion. This nested structure allows the inner straight portion to rotate within the outer curved portion without compromising the outer shape.
2Reliability
If the lead requires excessive tissue penetration for anchoring, then the lead can be securely fixed in place, but the accuracy and stability of cardiac rhythm management devices are compromised
Solution Approach 1:
The inner tubular portion is designed to be rotatable relative to the outer tubular portion, allowing dynamic adjustment during fixation. The active fixation element on the inner portion can rotate to engage tissue anchors while the outer curved portion remains stationary, maintaining precise lead placement without requiring excessive tissue penetration.
Solution Approach 2:
The active fixation element on the inner tubular portion automatically engages with tissue anchors through rotation, securing the lead in place without requiring excessive penetration depth. The rotatable inner portion self-adjusts to achieve secure fixation while maintaining the precision of the outer curved portion's placement.
3Ease of operation
If the inner tubular portion is made flexible to allow rotation, then the active fixation element can affix to tissue, but the curved shape of the lead may not be maintained during rotation
Solution Approach 1:
The outer tubular portion is designed with different mechanical properties than the inner tubular portion. The outer portion is stiffer and maintains the preformed curved shape, while the inner portion is more flexible to allow rotation. This local differentiation of mechanical properties allows rotation capability without compromising the overall curved shape.
Solution Approach 2:
The outer tubular portion is preformed with a specific curved shape that is maintained during inner portion rotation. The curvature of the outer portion acts as a stable framework that preserves the lead's navigable shape even as the inner straight portion rotates for fixation.
4Ease of operation
If the inner coil conductor has a steeper filar pitch along the curved section, then the inner tubular portion gains flexibility for rotation, but the conductor's structural strength is reduced
Solution Approach 1:
The inner coil conductor is designed with a steeper filar pitch specifically along the curved section to provide flexibility for rotation, while maintaining a standard filar pitch in other sections to preserve structural strength where needed. This localized variation in filar pitch optimizes both flexibility and strength in different regions of the conductor.
Data Source
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AI summary
Various embodiments concern a lead having a proximal section and a curbed section. The lead can comprise an outer tubular portion having a bias such that the lead assumes a curved shape along the curved section. The lead can further include an inner tubular portion extending within the outer tubular portion, the inner tubular portion comprising an inner coil conductor and an inner polymer jacket over the inner coil conductor along the curved section, the inner tubular member stiffer along the proximal section than the curved section, the outer tubular portion stiffer along the curved section relative to the inner tubular portion along the curved section such that the inner tubular portion can rotate relative to the outer tubular portion while the curved shape is substantially maintained. Relative rotation can extend and rotate and active fixation element.