BIOLOGICAL RESPONSE TO BARD CLAMSHELL SEPTAL OCCLUDERS IN THE CANINE HEART

Background The Clamshell Septal Occluder has been used to close variou s congenital heart defects. The purpose of this study was to evaluate the long-term biological response to this device after placement in th e canine heart. Previous in vivo studies with device placement were li mited to 60 days. Methods and Results An atrial septal defect was crea ted 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 placeme nt with groups of dogs euthanitized at the same intervals. Gross and m icroscopic assessment was done on the explanted devices. The implants were covered at least 50% by neointima at 1 month and covered complete ly by 3 months. There was no thrombus formation. Areas of focal hemorr hage were evident at 1 month and were not present at 3 months. The fib rous capsule that covered the device became more densely organized and neovascularized by 2 years. A focal foreign body reaction at the devi ce-tissue interface persisted for 2 years. There were no arm fractures with either the old or new devices in these dogs. Conclusions The Bar d Clamshell Septal Occluder is well tolerated in the canine heart for at least 2 years and elicits a normal healing process.