Objective-To establish the implantation technique for the atrial septal def
ect occluder system (ASDOS) device in an experimental animal model and to d
etermine long term mechanical stability of the device and its in vivo prope
rties in terms of biocompatibility and tissue reaction.
Materials and methods-An atrial septal defect was created and the device im
planted in 17 pigs (mean weight 30 kg). The implantation technique was refi
ned and modified because of initial technical and anatomical complications
during nine acute pilot studies. The technique proved to be feasible in eig
ht subsequent survival studies. Four pigs were electively killed three mont
hs after implantation (group 1). The remaining four pigs were killed six mo
nths after implantation (group 2).
Results-Necropsy showed all devices were embedded in soft tissue three mont
hs after implantation. Microscopic examination of atrial septal tissue show
ed an acute granulomatous inflammatory reaction in group 1 and fibrosis in
group 2. The intensity of the inflammatory reaction around the device was c
learly milder in group 2, indicating a decline in the inflammatory response
with time. Clinical and biochemical investigations indicated acceptable bi
ocompatibility of the device.
Conclusion-The implantation technique for the ASDOS device in a chronic pig
model has been established. Biocompatibility of the device was acceptable.