The authors should be congratulated for their pioneering work in this field. Innovative biomedical engineering was translated into clinical practice and led to the development of specific material characteristics for the framework, fabric, and design of this new device which appears to overcome a key limitation of previous, bioresorbable occluders: mismatch between device degradation and incomplete endothelialization and consequent defect recanalization. This novel device, as compared with other bioresorbable and conventional occluders, contains two distinct bioresorbable frameworks, one with a fast and one with a slow degradation rate: polydioxanone (PDO) filaments offer enough stability to allow complete endothelialization before it starts to degrade at an early stage (i.e., after 3 months), and the covering poly-L-lactic acid fabric which has a lower degradation rate thereby prevents VSD recanalization at a later stage. As compared with a metal framework, the PDO framework is less elastic and occluder shaping is supported by a shape line on the left disc of the device. However, the PDO filaments have good echocardiographic visibility and allow device implantation under complete echocardiographic guidance. A zero-fluoroscopy approach is especially appealing in young children included in this study population (mean age 4 years), to minimize lifetime X-ray exposure. Especially in the young, lifetime management is important. Fully bioresorbable devices may have the ability to change our management and improve the quality of care. With the here presented technology, serious complications including device erosion, perforation, thrombus formation, or infection might be prevented. Furthermore, with the rising number of transcatheter-based left-sided heart interventions requiring transseptal access, the development of similar fully bioabsorbable occluders for the closure of patent foramen ovale and atrial septal defects potentially allowing uncomplicated repeat transseptal access is an unmet, yet important need, starting to be addressed [4]. There are potential risks related to any fully resorbable technology. First, it will be difficult to impossible to localize and retrieve a device in the untoward event of embolization because it is not radio-opaque. Hence, the embolization of such a device may have more serious consequences than the embolization of conventional devices. Second, the resilience of new tissue formed in the process of device resorption may not be adequate in the long term, especially in the presence of large pressure differences between chambers (i.e., between the ventricles). Third, it is conceivable that ‘‘neo-tissue” will not grow and continue to seal the defect in a growing individual. Fourth, though ultimately replaced by new tissue, it may not prevent potential initial compression, trauma, or inflammation of the conduction tissue. In this context, the absence of complete atrioventricular block with the here-described device is intriguing and encouraging.
