Leadless Pacemaker Fixation Structure for Dual-Chamber Pacing
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Solution Overview
Problem
Existing leadless cardiac pacemakers face challenges with insecure fixation, particularly when attempting to screw into thin atrial walls, leading to hazards like atrial perforation, and are limited to univentricular pacing, incapable of dual-chamber pacing due to fixation reliance on the right ventricular apex.
Innovation Solution
A delivery device and cardiac pacing system featuring a fixation structure with a casing, driving member, and elastic member that allows for adjustable penetration and retrieval, enabling secure fixation in various tissue thicknesses and allowing dual-chamber pacing through telescopic movement and thread engagement, facilitating atrial or ventricular pacing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a helical feature is used to screw into the right ventricular apex for fixation, then the pacemaker can be securely fixed, but it is limited to univentricular pacing and cannot achieve dual-chamber pacing
Solution Approach 1:
The fixation mechanism is segmented into multiple independent fixation members (e.g., first fixation member for ventricular apex, second fixation member for atrial wall) that can be independently deployed and adjusted. This allows the pacemaker to achieve secure fixation while enabling dual-chamber pacing capability by fixing to both ventricular and atrial walls separately.
2Adaptability or versatility
If the fixation mechanism is designed to screw into thin atrial walls, then dual-chamber pacing becomes possible, but severe hazards such as atrial perforation and insecure fixation occur
Solution Approach 1:
Different fixation members are designed with locally optimized properties: the first fixation member for ventricular apex uses a helical screw design suitable for thick tissue, while the second fixation member for atrial wall uses a non-helical design (e.g., barbed, corkscrew, or expandable structure) optimized for thin tissue to prevent perforation while maintaining secure fixation.
Solution Approach 2:
The fixation members are designed with dynamic deployment characteristics, allowing gradual engagement with the tissue wall. The fixation members can be deployed in a controlled manner from a compressed state to an expanded/engaged state, enabling secure fixation without sudden perforation of thin atrial walls.
3Reliability
If the fixation mechanism relies on screwing action into the ventricular apex, then fixation is achieved, but the pacing location cannot be adjusted or retrieved
Solution Approach 1:
The fixation members are designed as dynamic, reversible structures that can be deployed and retrieved. The delivery device maintains compression on the fixation members during delivery, and upon deployment, the fixation members can be engaged with the tissue wall. If adjustment or retrieval is needed, the fixation members can be compressed back into the pacemaker body through the delivery device, allowing repositioning or complete removal without requiring surgical extraction.
4Object-affected harmful factors
If a circular ring-shaped feature is added to tether the leadless pacemaker, then prevention of entry into blood circulation is achieved, but device complexity increases
Solution Approach 1:
The tethering function is merged with the existing fixation members. The same fixation members that provide secure attachment to the heart wall also serve as tethers that prevent the pacemaker from entering the blood circulation system. This eliminates the need for a separate circular ring-shaped tethering feature, maintaining device simplicity while achieving the safety function.
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 solution provides secure fixation without tissue thickness limitations, enabling dual-chamber pacing with atrioventricular synchronization, simplifying the implantation process and reducing risks associated with existing pacemakers.
Implementation Method 1
an elastic member accommodated in the first internal cavity, one end of the elastic member coupled to the driving member and the other end extending outwardly from the driving member and being inserted in the slot
Implementation Method 2
the driving member may define an external thread and an inner wall of the casing that corresponds to the first internal cavity defines an internal thread engageable with the external thread
Data Source
AI summary
A delivery device, a cardiac pacing device and a fixation structure are disclosed. The fixation structure includes a casing, a driving member and an elastic member. The casing has a first internal cavity and a slot, and the driving member is partially received in the first internal cavity in such a manner that one end of the driving member protrudes out of the first internal cavity from a proximal end thereof and is detachably connected to the driving sheath. The elastic member is accommodated in the first internal cavity in such a manner that its one end is coupled to the driving member and the other end extends outwardly from the driving member and is inserted in the slot. The driving member is configured for fitted connection with the casing while being able to move in an axial direction of the casing to drive the elastic member to move in the slot, thereby causing the elastic member to protrude out of or move back into the slot. As such, the cardiac pacing device can be fixed in a patient's body, allows retrieval and adjustment in pacing location, and features a simple structure, ease of operation, no limitation in tissue wall thickness and ease of fixation. Thus, the leadless pacing device can be fixed either in a ventricle or in an atrium to provide dual-chamber pacing and physiological pacing with atrioventricular synchronization.