Shape-Memory Polymer-Based Occluder for Percutaneous Closure of Ventricular Septal Defect

Ventricular septal defect (VSD) remains one of the most prevalent congenital cardiac anomalies in pediatric populations. Percutaneous interventional closure has gradually replaced conventional open thoracotomy for selected patients, yet commercially available occluders are predominantly fabricated from metallic nitinol mesh, which carries long-term risks such as endothelialization delay, metal fatigue, and persistent foreign-body response. This work proposes a biodegradable shape-memory polymer occluder engineered for minimally invasive VSD repair. The device adopts a dual-disc structure integrated with a self-expanding shape-memory matrix, which can be compressed into a low-profile delivery catheter and recover its predefined geometric configuration upon reaching the physiological temperature inside the cardiac chamber. Systematic in vitro mechanical characterization demonstrates that the optimized polymer formulation provides sufficient radial support while maintaining appropriate flexibility to accommodate cyclic cardiac deformation. In a porcine animal model, the implanted occluder exhibits progressive degradation synchronized with neointimal ingrowth, and no severe complications including arrhythmia, device embolization or residual shunt are observed during the 6-month follow-up period. Compared with metallic counterparts, the bioresorbable occluder eliminates permanent metallic implants in the heart and reduces the requirement for long-term imaging surveillance. Nevertheless, further refinements are required to regulate the degradation rate and improve anti-thrombogenic surface performance before large-scale clinical translation.