Evaluation of Different Approaches for Atrial Septal Defect Closure

Objectives: Transcatheter closure of atrial septal defects (ASD) and patent foramen ovale (PFO) is the therapeutic gold-standard. However, current devices consist of a lot of foreign material and are stiff, and therefore cannot adapt to the anatomy. The underlying mechanism of fixation relies on compression which can lead to tissue damage and complete heart blocks, for example. Thus, there is a big need for alternative materials and closure techniques. The aim of the study was evaluation of closure approaches with flexible patch materials and tissue adhesives in an in vitro burst pressure setup and an ex vivo beating heart model.

Methods: ASD and PFO were created in epicardial slices of porcine hearts. A burst pressure setup and an ex vivo beating heart model were developed to determine pressures which can be withstand after closure. The defects were closed with novel and established approaches: sutures in combination with poly (glycerol sebacate urethane (PGSU) patches, a biocompatible and biodegradable elastomer (I), pericardial patches (PP) treated with glutaraldehyde (II), and without treatment (III), fibrin glue alone (IV), and Tachosil patches (V). The maximum burst pressure was determined.

Result: Sutured PGSU patches, as well as treated and untreated PP, showed sufficient tensile strength and withstood supraphysiological burst pressures after PFO (maximum pressure of 217.2 ± 6.2 mm Hg for PGSU patches and 250 ± 0 mm Hg for treated and untreated PP; n = 18) and ASD closure (maximum pressure of 138.2 ± 26.1 mm Hg for PGSU patches and 221.8 ± 9.0 mm Hg for treated PP; n = 18). In contrast, fibrin glue alone achieved maximum burst pressures of 62.7 ± 5.5 mm Hg after PFO closure (n = 24) and Tachosil patches achieved maximum burst pressures of 67 ± 9.5 mm Hg after PFO (n = 18) and 50.7 ± 6.2 mm Hg (n = 18) after ASD closure. Furthermore, maximum burst pressures for closure of PFOs with fibrin glue alone and ASDs with Tachosil patches were 20.3 ± 2.9 mm Hg (n = 3) and 80.7 ± 11.8 mm Hg (n = 3) in the beating heart model, respectively.

Conclusion: We present a reliable burst pressure setup and an ex vivo beating heart model for evaluation of closure approaches for cardiac septal defects. Treated and untreated PP showed no difference in maximum burst pressures although handling of treated patches was easier. All approaches showed sufficient adhesive strength to overcome the existing atrial pressures (up to at least 20 mm Hg) and therefore have potential to be used for the development of novel closure approaches of ASDs or PFOs.