Animal Experimental Study of Bioabsorbable Left Atrial Appendage Occluder

Abstract

Left atrial appendage (LAA) closure can prevent stroke in high-risk patients with atrial fibrillation.

A bioabsorbable LAA occluder made of degradable polymer materials, such as polydioxanone (PDO) and poly-L-lactic acid (PLA), and nitinol wire was used. Occluders were successfully implanted in 18 Chinese rural dogs, 2 of which died within 48 hours after operation due to pericardial tamponade and hemorrhage, respectively. Follow-up observation was performed after transcatheter LAA closure. New tissue was found on the surface of the occluder 2 months after operation. No adjacent structures such as the mitral valve and the left superior pulmonary vein were affected by the occluder discs. Hematoxylin and eosin (HE) staining was performed at 3 months after operation, which showed intact intimal structure on the occluder surface, and unabsorbed PDO and PLA were observed. Scanning electron microscopy showed irregular arrangement of endothelial cells. New endothelial tissue was observed to completely cover the occluder at 6 months after operation. Most PDOs were replaced by fibrous connective tissue, and scanning electron microscopy showed regularly arranged endothelial cells. Pathological examination at 12 months showed only a small remnant of PDO. The gross specimens of the liver, spleen, and kidneys and pathological examination did not indicate thromboembolism.

The bioabsorbable LAA occluder made of PDO, PLA, and nitinol wire was safe and effective for the occlusion of LAA in dogs. The surface of the occluder was endothelialized half a year after operation. The absorbable materials of the occluder were degraded after 1 year.