SMP-Foam Sheathed Embolization for LAA Particulate Containment
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Solution Overview
Problem
Current endovascular devices for closing the left atrial appendage (LAA) face challenges such as air embolism, pericardial effusions, tissue tearing, device embolization, stroke, and incomplete occlusion, while existing percutaneous devices lack a volume-filling occlusion member and generate harmful particulates.
Innovation Solution
A sheathed embolization device (SED) composed of shape memory polymer (SMP) foam encapsulated within a thin polymeric membrane to mitigate particulate generation, integrated with nitinol for fluoroscopic guidance and cavity sealing, featuring a detachment mechanism for delivery and deployment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If existing percutaneous devices are used for LAA closure, then the procedure can be performed minimally invasively, but harmful particulates are generated and adverse events occur
Solution Approach 1:
The patent employs a thin polymeric membrane that encapsulates the SMP foam, forming a flexible shell structure. This membrane acts as a containment barrier that prevents particulate matter from escaping into the bloodstream while allowing the device to maintain its minimally invasive percutaneous delivery profile. The flexible nature of the membrane enables it to conform to the device geometry and expand/contract with the SMP foam during deployment.
Solution Approach 2:
The polymeric membrane serves as an intermediary layer between the SMP foam and the surrounding biological environment. It mediates the interaction by filtering and containing potential particulates from the SMP foam while still permitting therapeutic effects (such as clotting and tissue ingrowth) to occur. This intermediary structure resolves the contradiction by blocking harmful particulates while maintaining the beneficial minimally invasive delivery method.
2Productivity
If SMP foam is used for occlusion, then rapid clotting and tissue ingrowth are achieved, but particulate generation occurs
Solution Approach 1:
The thin polymeric membrane encapsulating the SMP foam creates a contained environment that preserves the rapid clotting and tissue ingrowth properties of the SMP foam while preventing particulate escape. The membrane's selective permeability and containment capability allow therapeutic effects to proceed at full speed while blocking harmful particulates from entering the circulation.
Solution Approach 2:
The membrane acts as an intermediary that separates the particulate-generating SMP foam material from the bloodstream, while still allowing the biochemical processes of clotting and tissue ingrowth to occur effectively. This resolves the contradiction by maintaining high productivity in occlusion while eliminating the harmful particulate side effect.
3Reliability
If conventional LAA closure devices are used, then stroke risk is reduced, but adverse events like air embolism and tissue tearing occur
Solution Approach 1:
The thin polymeric membrane provides a flexible, conforming barrier that reduces mechanical trauma to surrounding tissues compared to rigid conventional devices. The flexibility of the membrane allows it to adapt to tissue contours, reducing the risk of tissue tearing while maintaining effective LAA occlusion for stroke prevention. The encapsulated structure also minimizes air pocket formation that could lead to air embolism.
4Reliability
If volume-filling occlusion is achieved with SMP foam, then complete LAA occlusion is obtained, but device complexity increases
Solution Approach 1:
The thin polymeric membrane adds only a minimal structural layer around the SMP foam, maintaining relative device simplicity while enabling complete volume-filling occlusion. The membrane's thin nature and flexibility allow it to conform perfectly to the SMP foam geometry, ensuring complete occlusion without adding significant structural complexity or interfering with the foam's expansion and clotting properties.
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 SED achieves rapid clotting, endothelialization, and tissue ingrowth, reducing adverse events like device thrombosis and migration, while effectively occluding the LAA and minimizing particulate generation, thus improving procedural outcomes and safety.
Implementation Method 1
SMP foams are capable of being compressed to fit inside a catheter and then actuating once exposed to body heat and water inside vasculature, achieving up to a 70-fold volume expansion
Implementation Method 2
To program SMPs, the material is heated above its glass transition (Tg) temperature, and an external stress is applied to deform the material to its secondary shape. The secondary shape is then fixed by cooling the material under constant load
Implementation Method 3
The porous architecture of the foams provides a large surface area for rapid clotting and connective tissue infiltration
Data Source
AI summary
An embodiment includes an apparatus comprising: a shape memory polymer (SMP) foam having an outside surface; and a membrane that encapsulates at least 50% of the outside surface of the SMP foam; wherein (a) the SMP foam includes a thermoset SMP, and (b) the membrane includes a thermoplastic polymer. Other embodiments are addressed herein.