Study of biodegradable occluder of atrial septal defect in a porcine model

Figures

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  Figure 1. Schematic drawing of (A) the previous PLLA ASD device and (B) the modified PLLA ASD device. Both A and B present (a) unlocked state, (b) locked state, and (c) device and delivery system. Six modifications have been made to device A that result in device B: Reduced PLLA wire meshes, screw connector, one more mark at the sealing tip of the left disc, a loader with flare angle, a locking system, downsized membrane

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  Figure 2. Leukocyte counts at pre‐procedure and at 1, 3, 6, and 12 months after implantations. No significant difference was found between biodegradable devices and control group

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  Figure 3. The X‐ray images before (A) and after (B) releasing the PLLA device. The arrows indicate marks. Seven marks were shown clearly after releasing the polymer device

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  Figure 4. Echo images at 6 months follow‐up. (A) Four chamber view; (B) short axis view. The arrows indicate the biodegradable device. The device exhibited an appropriate shape and no residual shunting

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  Figure 5. Gross appearances of a PLLA device (A–C) and a metal device (D–F) taken from the pigs at indicated follow‐up spots. (A) At 3 months, the left disc (arrow) of a PLLA device was completely covered by new endothelial tissue, and PLLA wires were not visible; (B) at 6 months, the left disc of the PLLA device was completely covered; (C) at 12 months, the left of the PLLA device was partially degraded, and the rest was still in a firm formation; (D) at 3 months, the left disc of the metal device was covered partially by new endothelial tissues; (E and F) at 6 months (E) and 12 months (F), the left disc was almost covered by new endothelial tissue, and the metal wires were still visible

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  Figure 6. HE staining of a PLLA occluder (A–C) and a metal occluder (D–F) at different follow‐up points (3 months for a and D, 6 months for B and E, and 12 months for C and F). At all of the three time points after implantation, the PLLA device (blue arrows) was surrounded by a large amount of collagen fibers (black arrows) and fibroblasts (green arrows). A moderate number of inflammatory cells and multinuclear giant cells could be observed; yet no necrotic tissue observed. The PLLA wires were partly degraded at 12 months. For the nonbiodegradable occlude, a large number of collagen fibers (black arrows) and fibroblasts (green arrows) surrounded the metal device (red arrows). A small number of inflammatory cells was also observed

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  Figure 7. Scanning electronic microscopic images of the PLLA occluder (A–C) and metal occlude (D–F) at different time points after implantation (×400). At 3 months (A) and 6 months (B), the PLLA occluders were covered by a layer of fibrous tissues. At 3 months (D) and 6 months (E), the metal occluders were not only covered by a layer of fibrous tissues, but also by many endothelial cells. At 12 months, both the PLLA occluders and the metal devices were covered by a large amount of endothelial cells