Inversion of Left Atrial Appendage Will Cause Compressive Stresses in the Tissue: Simulation Study of Potential Therapy

Figures

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  Figure 1. Schematic of LAA closure device and approach. The progression of the procedure is from (A–H). (A): Insert device into the LAA. (B): Deploy suction flute. (C): Suction onto inside distal wall of the LAA. (D): Pull the LAA inward and invert it. (E): Extend needle into inverted space. (F): Inject adhesive through needle-tip hypo-tube wire with side holes (blind closed tip). (G): Retract needle and maintain suction until adhesive cures. (H): Remove closure device leaving only tissue glue behind. The inversion of the LAA apex is not to scale, and can be much less, depending on the length of the LAA.

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  Figure 2. LA model (green) as extrapolated from the LHHM (grey); insertions show LAA mesh at undeformed and deformed configurations.

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  Figure 3. Color-coded stress distributions in the human left atrium during inversion of the LAA. Highest compressive (negative) stress (-1 MPa) is shown in dark blue; highest tensile (positive) stress (1 MPa) is shown in dark red. The progression of the procedure is from #1 to #6. #1: Baseline, before any LAA inversion. #2: LAA is 20% inverted; compressive stress is seen near tip of LAA. #3: LAA is 40% inverted; compressive stress is seen over a larger portion of the LAA. #4: LAA is 60% inverted; compressive, as well as some tensile stress, is visible in LAA. #5: LAA is 80% inverted; only compressive stress is visible in LAA. #6: LAA is 100% inverted; only compressive stress is visible in LAA.

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  Figure 4. (A) Average stress at LAA tip as a function of displacement of the clamped nodes: (B) pulling force needed for LAAI as a function of simulation time.

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  Figure 5. Flow velocity streamlines in the atrial chamber at peak systole of E-wave (top row) and diastole (bottom row) for both the non-inverted and inverted LAA.

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  Figure 6. Flow velocity streamlines (top row) and velocity vector at a cross section for both the LAA and LAAI.

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  Figure 7. Mean flow velocity over one cardiac cycle at the tip of LAAI and in a cross-section of LAA (see inset).