Left Atrial Appendage Occlusion Device: Evaluation of Surgical Implant Success and in Vivo Corrosion Performance

Objective: The purpose of this study was to compare the in vivo corrosion resistance of the implanted titanium, nitinol annular occlusion device to a control device, i.e. an implantable device containing nitinol, approved by the FDA and currently on the market. Methods: The annular occlusion device is a self-closing, implantable clip. Three canines underwent placement of devices on the left and right atrial appendages. Two Vnus U-clips were secured to either atrium. On post-operative day 95, animals underwent en-bloc cardiac resection via the previous left thoracotomy incision. The annular occlusion device and U-clips were dissected free from the atria. The polyester fabric and tissue ingrowth were removed from the devices and were sent for corrosion analysis. Results: Gross examination of resected hearts of two canines revealed no abnormalities. The compressed endocardial surfaces were completely fused and the appendages fully necrosed. All devices were located and harvested. The annular occlusion device clips and Medtronic Vnus U-clips were evaluated using scanning electron microscopy. Both low and high magnification examination of the nitinol springs and the site of insertion of the nitinol springs into the titanium tubes in the annular occlusion device showed no evidence of localized corrosion. In no case was any evidence of general or localized corrosion found in the form of metallic oxidation. Conclusion: The annular occlusion device provides safe and reliable exclusion of the left atrial appendage without evidence of general or localized corrosion over the 95-day exposure period in canines and may therefore provide a reasonable therapeutic option for stroke risk reduction in patients with atrial fibrillation.