Atrial Septal Defect Device Closure in the Pediatric Population: A Current Review

Biodegradable polymeric occluder with controllable locking structure for closure of atrial septal defect via interventional treatment

Atrial septal defect (ASD) is one of the major congenital heart diseases, and transcatheter closure with a cardiac occluder is a modern method to treat ASD with the advantage of mini-invasiveness over traditional surgical closure. While current occlusion devices are mainly made of non-degradable nitinol with superelasticity, the permanent existence of a metal in vivo may trigger potential complications and especially has an adverse effect on the heart development for children. However, it is challenging to invent a superelasticity-free occluder that can be delivered through a catheter but firmly locked after being opened at the target site; it is also much desired for research and development to quickly assess the feasibility of a superelasticity-free occluder in vitro. Herein, a biodegradable poly(L-lactide) (PLLA) occluder composed of a braided PLLA frame as the skeleton and a nonwoven PLLA fabric as the flow-blocking membrane is developed, and a controllable locking structure is designed to enable firm closure for a device even without superelasticity. We also suggest and justify a series of in vitro methods to assess the efficacy of the biodegradable occluder, and the results confirm the reliability of locking, water-blocking, mechanical strength and degradability. It is found that the PLLA fabric with moderate fiber density is optimal for surface endothelialization. We also carry out biological assessments; significant endothelialization and alleviated inflammation response are observed after 6 months of subcutaneous implantation into rabbits. The porcine model illustrates that the biodegradable polymeric occluder can be successfully implanted into the atrial septum via transcatheter intervention; the follow-ups have confirmed the safety and efficacy of this biodegradable polymeric occluder with the controllable locking structure.

Outcomes of Device Closure of Atrial Septal Defects

Several devices have been designed and tried over the years to percutaneously close atrial septal defects (ASDs). Most of the devices were first experimented in animal models with subsequent clinical testing in human subjects. Some devices were discontinued or withdrawn from further clinical use for varied reasons and other devices received Food and Drug Administration (FDA) approval with consequent continued usage. The outcomes of both discontinued and currently used devices was presented in some detail. The results of device implantation are generally good when appropriate care and precautions are undertaken. At this time, Amplatzer Septal Occluder is most frequently utilized device for occlusion of secundum ASD around the world.

Biodegradable atrial septal defect occluders: A current review

Atrial septal defect (ASD) is a common structural congenital heart disease. With the development of interventional closure devices and transcatheter techniques, interventional closure therapy has become the most well-accepted therapeutic alternative worldwide, as it offers a number of advantages over conventional therapies such as improved safety, easier operation, lower complication rates and invasiveness, and shorter anesthetic time and hospitalizations. During the past decades, various types of occluders based on nondegradable shape memory alloys have been used in clinical applications. Considering that the permanent existence of foreign nondegradable materials in vivo can cause many potential complications in the long term, the research and development of biodegradable occluders has emerged as a crucial issue for interventional treatment of ASD. This review aims to summarize partially or fully biodegradable occlusion devices currently reported in the literature from the aspects of design, construction, and evaluation of animal experiments. Furthermore, a comparison is made on the advantages and disadvantages of the materials used in biodegradable ASD occlusion devices, followed by an analysis of the problems and limitations of the occlusion devices. Finally, several strategies are proposed for future development of biodegradable cardiac septal defect occlusion devices. STATEMENT OF SIGNIFICANCE: Although occlusion devices based on nondegradable alloys have been widely used in clinical applications and saved numerouspatients, biodegradable occlusion devices may offer some advantages such as fewer complications, acceptable biocompatibility, and particularly temporary existence, thereby leaving "native" tissue behind, which will certainly become the development trend in the long term. This review summarizes almost all partially or fully biodegradable occlusion devices currently reported in the literature from the aspects of design, construction, and evaluation of animal experiments. Furthermore, a comparison is made on the advantages and disadvantages of the materials used in biodegradable ASD occlusion devices, followed by an analysis of the problems and limitations of the occlusion devices. Finally, several strategies are proposed for future development of biodegradable cardiac septal defect occlusion devices.

Recent advances in managing septal defects: atrial septal defects

The purpose of this review is to discuss the management of atrial septal defects (ASD), paying particular attention to the most recent developments. There are four types of ASDs: ostium secundum, ostium primum, sinus venosus, and coronary sinus defects. The fifth type, patent foramen ovale-which is present in 25 to 30% of normal individuals and considered a normal variant, although it may be the seat of paradoxical embolism, particularly in adults-is not addressed in this review. The indication for closure of the ASDs, by and large, is the presence of right ventricular volume overload. In asymptomatic patients, the closure is usually performed at four to five years of age. While there was some earlier controversy regarding ASD closure in adult patients, currently it is recommended that the ASD be closed at the time of presentation. Each of the four defects is briefly described followed by presentation of management, whether by surgical or percutaneous approach, as the case may be. Of the four types of ASDs, only the ostium secundum defect is amenable to percutaneous occlusion. For ostium secundum defects, transcatheter closure has been shown to be as effective as surgical closure but with the added benefits of decreased hospital stay, avoidance of a sternotomy, lower cost, and more rapid recovery. There are several FDA-approved devices in use today for percutaneous closure, including the Amplatzer® Septal Occluder (ASO), Amplatzer® Cribriform device, and Gore HELEX® device. The ASO is most commonly used for ostium secundum ASDs, the Gore HELEX® is useful for small to medium-sized defects, and the cribriform device is utilized for fenestrated ASDs. The remaining types of ASDs usually require surgical correction. All of the available treatment modes are safe and effective and prevent the development of further cardiac complications.