UmbreLAA
Blood clots in the left atrial appendage (LAA) are a leading cause of ischemic stroke in non-valvular atrial fibrillation (AF). Complications with oral anticoagulants (OACs) and the success of LAA closure devices have increased interest in mechanical occlusion. Current devices struggle with diverse LAA anatomies, prompting development of a novel endocardial LAA occluder offering greater variability.
Team Members
Gari Eberly, Madison Reddie, Diego Alonso Quevedo Moreno
Advisors
Keagan Mendez, Ellen Roche
Affiliation
Boston Scientific, Institute for Medical Engineering and Science - MIT
My Role
Design, Prototyping, Testing
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Process
We started by analysing prior art and then defining the functional requirements. We explored three LAA removal approaches: ablation, ligation, and plugging, selecting the latter for its low invasiveness, high safety, and familiarity. The functional requirements guided the process, emphasizing anatomical accommodation. Concepts were developed, analyzed, and down-selected using Pugh charts. Prototypes were iteratively created with proxy materials, refining the design to a final version.
.png)
Process
We started by analysing prior art and then defining the functional requirements. We explored three LAA removal approaches: ablation, ligation, and plugging, selecting the latter for its low invasiveness, high safety, and familiarity. The functional requirements guided the process, emphasizing anatomical accommodation. Concepts were developed, analyzed, and down-selected using Pugh charts. Prototypes were iteratively created with proxy materials, refining the design to a final version.
We went through a lot of different designs and mechanisms before settling on the final one which was inspired by an umbrella, hence the name - UmbreLAA.
New Design
Existing Design
New Design
Results
Cost reduction of 95% and weight reduction of 50% was achieved. The prototypes of the design were built and tested extensively. The process plan has been defined and documented. The supply chain for the materials has been set up. The assembly line has been set up in MIT Building 35. 25 FrEDs have been successfully manufactured and are ready to be deployed to the end users.
Old Design | New Design | |
|---|---|---|
Minimum Extruded Fiber Diameter | ~0.2 mm | 0.15 mm |
Weight | ~10 lbs | 5 lbs |
Unit Costs | $5428 | $269 |
Adaptable LAA Occlusion
01
To reduce rates of device-anatomy mismatch, and thereby also increase the number of people that can benefit from mechanical occlusion of the LAA, we designed a device that both supports a larger range of anatomical variation and whose width can be changed in-situ to match the specific anatomy of the patient - the UmbreLAA.
02
Unlike other commercially available devices on the market, the base diameter of the UmbreLAA can be changed during insertion by a trained operator, thereby allowing large ranges of LAA diameters to be accommodated by a single device size.
03
The UmbreLAA consists of two main parts: the expandable plug and an accompanying pacifier module. The plug anchors to the wall of the LAA and its width can be adjusted in-situ to effectively seal the LAA. The pacifier sits just outside the LAA ostium and provides a second seal against clot embolization. The frame of the UmbreLAA consists of a flexible silicone frame with elastic joints that allow the device to collapse within a catheter for percutaneous delivery. The final device will be covered in a PET membrane to support re-endothelialization after insertion.
The Prototype
Leaving this area for any text you may want for the Prototype above and the video to the right.
02
We repeated these tests in both static and dynamic conditions. In the dynamic condition, we contracted the LAA molds by 25% at a rate of 60 contractions per minute to simulate the effect of the beating heart. Moving forward, we will display the results of the dynamic tests as they more closely resemble physiological conditions.
Testing
The following tests were performed and UmbreLAA was benchmarked against the WatchmanFLX:
Conformability
We tested the prototype’s ability to conform in different ostium shapes and identified peri-device gaps, represented here in black.
Sealing
We tested its ability to seal against leaks by measuring the amount of material that can pass through these gaps.
Stability
We quantified device stability by measuring the amount of force required to pull the device out of the LAA models.
Future Work
Future efforts will include fabricating high-fidelity prototypes with biocompatible, non-thrombogenic materials. Accelerated aging and fatigue testing will validate long-term durability. Development of deployment tools and procedures will prioritize minimally invasive techniques. In vivo animal studies will assess safety and efficacy, focusing on the anchoring hooks' interaction with cardiac tissue.
Results
UmbreLAA prototypes exhibited superior anchorage and reduced peri-device leakage compared to the WATCHMAN FLX. Dynamic tug tests demonstrated significantly higher dislodgement forces, validating the inclusion of larger hooks and additional prongs. The addition of the pacifier module effectively mitigated leakage in extreme anatomical models, ensuring robust sealing capabilities.
Conformability
Sealing
Stability
Results
UmbreLAA prototypes exhibited superior anchorage and reduced peri-device leakage compared to the WATCHMAN FLX. Dynamic tug tests demonstrated significantly higher dislodgement forces, validating the inclusion of larger hooks and additional prongs. The addition of the pacifier module effectively mitigated leakage in extreme anatomical models, ensuring robust sealing capabilities.
Sealing
Conformability
Stability