Torque Limiter for Leadless Cardiac Device Anchoring
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Solution Overview
Problem
Existing active implantable medical devices face challenges in securely anchoring to heart tissue without causing tissue damage, particularly due to excessive torque during implantation, which can lead to tearing or puncturing, especially in thin heart walls.
Innovation Solution
A delivery system with a torque limiter mechanism is employed, featuring a catheter with a torque shaft and a torque limiter component that couples to the leadless capsule, limiting radial torque after anchoring to prevent further rotation and tissue damage, using a deformable elastic component like a coil spring to control torque transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a helical screw anchoring mechanism is used to penetrate and anchor the medical device to the tissue, then secure anchoring is achieved, but excessive torque can cause tissue damage such as tearing or puncturing
Solution Approach 1:
A torque limiter mechanism is introduced as an intermediary component between the delivery catheter and the leadless capsule. This mechanism includes a torque shaft, a torque limiter component (such as a deformable elastic component or friction-based limiter), and a docking feature. The torque limiter component is positioned between the torque shaft and the capsule to intercept and limit excessive torque before it reaches the anchoring screw and tissue.
Solution Approach 2:
The torque limiter mechanism changes the torque parameter transmitted to the capsule by imposing a maximum torque threshold. When the applied torque exceeds this threshold, the torque limiter component deforms or slips, preventing further torque transmission. This parameter change ensures that the torque remains within a safe range that secures anchoring without causing tissue damage.
2Productivity
If continuous rotation is applied during implantation to advance the anchoring screw, then penetration and anchoring are achieved, but excessive rotation after anchoring can cause tissue damage
Solution Approach 1:
The torque limiter mechanism provides automatic feedback control through its deformable or friction-based component. As rotation continues and torque builds up, the torque limiter component responds by deforming or slipping when the torque threshold is reached, automatically stopping further torque transmission without requiring external intervention. This feedback mechanism allows continuous rotation to proceed safely.
Solution Approach 2:
The torque limiter mechanism is self-regulating and does not require external control systems or additional actuators. The deformable elastic component or friction interface automatically limits torque based on its mechanical properties, making the system self-service in preventing excessive rotation and tissue damage.
3Reliability
If high torque is applied to ensure firm anchoring of the capsule, then secure fixation is achieved, but the risk of cardiac tamponade increases due to potential heart wall puncture
Solution Approach 1:
The torque limiter mechanism provides beforehand cushioning by pre-establishing a torque threshold that prevents excessive force application. The deformable elastic component or friction-based limiter is designed to engage before dangerous torque levels can be reached, cushioning against potential tissue damage and cardiac tamponade before they can occur.
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 torque limiter ensures secure anchoring of the leadless capsule without causing tissue damage, allowing for safe implantation and preventing cardiac tamponade by limiting torque after the capsule is fully anchored, thus enhancing the safety and effectiveness of the implantation procedure.
Implementation Method 1
using a deformable elastic component like a coil spring to control torque transmission
Data Source
Figure 1A
Figure 1B~2B
Figure 3A~3B
AI summary
A torque limiting mechanism between a medical device and an implantation accessory is disclosed. In a particular embodiment, a delivery system for a leadless active implantable medical device includes a delivery catheter and a torque shaft (428) disposed within the delivery catheter. The delivery system also includes a docking cap (416) having a distal end for engaging an attachment mechanism of the leadless active implantable medical device. The delivery system also includes a torque limiting component (424) coupled to a distal end of the torque shaft and a proximal end of the docking cap.