Biological response to Bard Clamshell Septal Occluders in the canine heart.

Overview

BACKGROUND: The Clamshell Septal Occluder has been used to close various congenital heart defects. The purpose of this study was to evaluate the long-term biological response to this device after placement in the canine heart. Previous in vivo studies with device placement were limited to 60 days. METHODS AND RESULTS: An atrial septal defect was created in dogs by blade septostomy followed by balloon dilation. Both old and new (redesigned) devices were placed. Angiographic follow-up was performed at 1, 3, and 6 months and 1 and 2 years after device placement with groups of dogs euthanitized at the same intervals. Gross and microscopic assessment was done on the explanted devices. The implants were covered at least 50% by neointima at 1 month and covered completely by 3 months. There was no thrombus formation. Areas of focal hemorrhage were evident at 1 month and were not present at 3 months. The fibrous capsule that covered the device became more densely organized and neovascularized by 2 years. A focal foreign body reaction at the device-tissue interface persisted for 2 years. There were no arm fractures with either the old or new devices in these dogs. CONCLUSIONS: The Bard Clamshell Septal Occluder is well tolerated in the canine heart for at least 2 years and elicits a normal healing process.