Polymeric and metallic occluders for interventional therapy of cardiovascular diseases

Interventional therapy has, as a minimally invasive approach, been widely adopted for treating cardiovascular diseases, particularly structural heart disease, where occluders play a pivotal role in transcatheter closure. This paper comprehensively reviews the evolutionary trajectory and emerging frontiers of cardiovascular occluders, beginning with their interventional applications in congenital heart defects (atrial septal defect, ventricular septal defect, patent foramen ovale, and patent ductus arteriosus) and left atrial appendage closure. The focus then shifts to occluder materials and design principles, tracing the progression from early non-degradable metals like stainless steel to the current gold standard, nitinol, whose hyperelasticity enables self-expanding devices. To promote rapid endothelialization on nitinol implants, surface nanocoatings of bioceramics such as titanium nitride have been developed to modulate cell-material interactions. To eliminate risks from permanent metallic implants, biodegradable occluders have emerged as an alternative. The design of biodegradable occluders utilizing medical polymers such as polylactic acid and polydioxanone is illustrated, highlighting structural innovations such as locking strategies to overcome the lack of hyperelasticity. Key considerations including matching degradation rate with tissue regeneration and achieving X-ray visibility are also described. Finally, future perspectives are presented: expanding applications to infants and the elderly, incorporating tissue engineering for in situ regeneration, and leveraging nanotechnology and artificial intelligence to optimize device performance. The ongoing advancement of occluder technologies will propel interventional therapy for structural heart disease toward a safer and more effective treatment.