Temporary Pacemaker Fixation in Vena Cava via Tissue Ingrowth
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Solution Overview
Problem
Leadless pacemakers face challenges such as potential blood regurgitation due to size constraints and limited functionality due to small size, which restricts features like cardiac event statistics and wireless telemetry, and existing fixation mechanisms for implantable medical devices in blood vessels are complex or require cutting for removal.
Innovation Solution
A temporary fixation system for an implantable medical device in the inferior vena cava using a stent-like mechanism that dissolves or is self-engaging, allowing a larger pacemaker with more features and functionality, which is securely held by tissue growth after initial temporary fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a leadless pacemaker is implanted directly into the heart, then the device size is reduced and lead-related complications are minimized, but the pacemaker may touch the cardiac valve causing blood regurgitation and functionality is limited due to size constraints
Solution Approach 1:
The pacemaker is relocated from the three-dimensional space of the heart chamber to the one-dimensional path of the venous system, specifically the inferior vena cava. This dimensional shift allows the device to be positioned in a larger vessel where it can grow into the wall for secure fixation without interfering with cardiac valve function, while still maintaining a compact form factor suitable for minimally invasive implantation.
Solution Approach 2:
The inferior vena cava serves as an intermediary location between the traditional pocket implantation and direct heart implantation. By placing the pacemaker in the vena cava, the device gains access to the heart's electrical system through the venous pathway while being supported by the vessel wall, thereby avoiding direct contact with cardiac valves and eliminating lead-related complications.
2Reliability
If a traditional fixation mechanism is used for the implantable medical device, then the device is securely held in place, but the fixation mechanism is complex and requires cutting for removal
Solution Approach 1:
The fixation mechanism utilizes the body's own biological processes to secure and eventually release the device. The pacemaker is designed to grow into the vessel wall through tissue ingrowth, providing self-securing fixation without complex mechanical components. For removal, the device can be extracted by collapsing the vena cava, leveraging the body's physiological structure rather than requiring surgical cutting or complex disassembly procedures.
Solution Approach 2:
The fixation mechanism relies on changes in the physical and biological parameters of the vessel wall over time. Initially, the device is positioned within the vena cava, and over several weeks, tissue grows around and into the device housing, changing the mechanical properties of the fixation from temporary to permanent. This parameter change eliminates the need for complex fixation structures while ensuring secure device placement.
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
Enables the use of larger pacemakers with enhanced functionality, secure implantation without the need for complex fixation removal, and allows for later explantation for battery replacement by using biodegradable materials or stimuli-responsive polymers for temporary fixation.
Implementation Method 1
The fixation mechanism or element is temporary in nature in that the fixation holds the implantable medical device in place until the implantable medical device is grown in to the wall of the vessel
Implementation Method 2
using biodegradable materials or stimuli-responsive polymers for temporary fixation
Data Source
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AI summary
A medical fixation system for temporary fixation of an implantable medical device such as a short lead pacemaker outside of the heart in a larger blood vessel such as the superior or inferior vena cava. The fixation mechanism or element is temporary in nature in that the fixation holds the implantable medical device in place until the implantable medical device is grown in to the wall of the vessel and the short lead attached to the implantable medical device and implanted in the heart is grown in. The cell tissue surrounding the implantable medical device and the short lead then keeps the implantable medical device in place without the temporary fixation element.