Atrial Septal Defect (ASD) Occluder–Histopathology in 59 Human Explanted Devices

Objectives: This study was aimed to evaluate and characterize tissue reactions within and at the surface of devices for interventional closure of atrial septal defects.

Methods: Explants were processed using a uniform protocol after surgical removal from humans. Devices were fixed in formalin and embedded in methyl methacrylate. Serial sections were obtained by sectioning with a diamond cutter and grinding, thus saving the metal/tissue interface for histological evaluation. Standard staining and immunohistochemistry was performed using conventional protocols.

Result: Fifty-nine devices were analyzed (amplatzer n = 29, cardioseal/starflex n = 10, biostar n = 5, helex n = 4, and others n = 11). Implants had been in the human body for 1 day to 15 years (mean 3.2 years). Main reason for explantation had been residual shunting in 20, thrombus formation, and/or clinical suspicion for embolism in 10, heart surgery otherwise indicated in 8, device dislocation in 7, deformity of the device in 5, damage to the right atrial wall in 3, and other reasons in 6 patients, respectively. Endothelialization and cellular organization of tissue within the devices was present in all specimen with implantation times >6 months. Lymphocytic infiltrations and local foreign body reaction related to textile components were found in almost all explants. No case of device related endocarditis was identified. Calcifications, partial corrosion of metal wires, and complete degradation of ivalon foam material were seen in explants with implantation time >7 years.

Conclusion: This is the largest cohort on ASD occlusion devices with complete histology workup after surgical explantation. We demonstrate timely endothelialization and tissue organization, a typical pattern of chronically persisting inflammation. Calcifications and material alterations with partial corrosion or even loss of “permanent” materials were seen in long-term explants. We conclude that patients with ASD occlusion devices should be followed life-long for detection of potential implant-related complications. Our findings may be relevant for development of new devices.