Recent developments in next-generation occlusion devices

Transcatheter closure has been widely accepted as a highly effective way to treat abnormal blood flows and/or embolization of thrombus in the heart. It allows the closure of four types of congenital heart defects (CHDs) and stroke-associated left atrial appendage (LAA). The four types of CHDs include atrial septal defect (ASD), patent foramen ovale (PFO), patent ductus arteriosus (PDA), and ventricular septal defect (VSD). Advancements in the materials and configurations of occlusion devices have spurred the transition from open-heart surgery with high complexity and morbidity, or lifelong medication with a high risk of bleeding, to minimally invasive deployment. A variety of occlusion devices have been developed over the past few decades, particularly novel ones represented by biodegradable and 3D-printed occlusion devices, which are considered as next-generation alternatives to conventional Nitinol-based occlusion devices due to biodegradability, customization, and improved biocompatibility. The aim here is to comprehensively review the next-generation occlusion devices in terms of materials, configurations, manufacturing methods, deployment strategies, and (if available) experimental results or clinical data. The current challenges and the direction of future work are also proposed. STATEMENT OF SIGNIFICANCE: Implantation of occlusion devices has become a widely accepted and highly effective treatment for occluding abnormal blood/thrombus flow within the heart. Due to the serious complications such as erosion and displacement of conventional Nitinol-based occluders, next-generation occluders with reduced risk of complications and improved biocompatibility has emerged. Here, we comprehensively review the next-generation occluders developed for atrial septal defect (ASD), patent foramen ovale (PFO), patent ductus arteriosus (PDA), ventricular septal defect (VSD), and left atrial appendage (LAA), with special emphasis on biodegradable occluders. Besides, intelligent materials (e.g., automatically deployable shape memory polymers) and rapid customized manufacturing methods (3D/4D printing) for the fabrication of occluders are also introduced. Lastly, the directions of future work are highlighted.

The Future of Paediatric Heart Interventions: Where Will We Be in 2030?

Purpose of Review

Cardiac catheterization therapies to treat or palliate infants, children and adults with congenital heart disease have developed rapidly worldwide in both technical innovation and device development in the previous three decades. By reviewing of current status of novel or development of devices and techniques, we will discuss what is likely to happen in paediatric heart intervention in the next decade.

Recent Findings

Recently, biodegradable stents and devices, transcatheter pulmonary valve implantation for the native right ventricle outflow tract and MRI-guided interventions have been progressing rapidly with good immediate to early results. These are expected to be introduced and spread in the next decade although there are still challenges to overcome.

Summary

The future of paediatric heart intervention is very promising with rapid development of technological progress.

A novel biodegradable occluder for the closure of ventricular septal defects: immediate and medium-term results in a canine model

OBJECTIVES

The feasibility of an Amplatzer septal occluder closure of ventricular septal defects (VSDs) under echocardiographic guidance has already been proven. However, the technique is not used routinely owing to high-rate atrioventricular blocks and the non-absorbability of the occluder. Here, we aimed to evaluate the safety, biocompatibility and effectiveness of a new biodegradable occluder.

METHODS

A total of 18 adult beagle dogs [mean body weight 8.85 kg (range 8.10-10.40 kg)] were enrolled in our study from March 2015 to July 2018. VSD animal models were prepared by thoracic intervention, and the new bioabsorbable occluder was implanted under the guidance of transthoracic echocardiography. Laboratory examinations, transthoracic echocardiography and electrocardiography were performed after surgery, and pathological samples from dogs were obtained after euthanasia and examined in the 1st, 3rd, 6th, 9th, 12th and 24th months to evaluate the safety, biocompatibility and effectiveness of the biodegradable occluder.

RESULTS

All the dogs received successful implantations of the biodegradable occluder and survived, showing no follow-up-related complications (such as dislocation, arrhythmia and recanalization). Biochemical tests showed no significant abnormalities or differences, except for an increase in white blood cells and C-reactive proteins on the day after the operation. Histopathological examinations revealed that the bioabsorbable occluders were biocompatible, while immunohistochemical evaluations and electron microscopy showed endothelial cells growing on the occluder surface.

CONCLUSIONS

The effective occlusion of VSD, good biocompatibility, rapid endothelialization and lack of complications shown by the biodegradable occluder in this study suggest that the device meets acceptable clinical safety and has potential application prospects.

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.

[Interventional closure of atrial septal defects, patent oval foramen and ventricular septal defects]

Percutaneous transcatheter closure techniques and devices for congenital intracardiac shunts have considerably improved; therefore, catheter closure is now the treatment of choice for atrial septal defects (ASD). This is technically feasible in more than 80% of patients with a secundum ASD and the success rate is higher than 99%. General anesthesia is as a rule unnecessary and the hospital stay is very short. A patent oval foramen (POF) is a potential cause of cryptogenic stroke and peripheral embolisms. The catheter occlusion has many advantages in comparison to lifelong anticoagulation therapy and for some patients it is the only therapeutic option. Randomized trials have shown that interventional closure leads to results which are comparable to drug therapy and for some occlusion systems even evidence of significant advantages compared to drug therapy was found. Even ventricular septal defects (VSD), including perimembraneous and post-myocardial infarction VSDs can be closed by catheter techniques with a high success rate.