Biofabrication in Congenital Cardiac Surgery: A Plea from the Operating Theatre, Promise from Science

Recent Development of Biodegradable Occlusion Devices for Intra-Atrial Shunts

Atrial septal defect (ASD) is the third most common type of structural congenital heart defect. Patent foramen ovale (PFO) is an anatomical anomaly in up to 25% of the general population. With the innovation of occlusion devices and improvement of transcatheter techniques, percutaneous closure has become a first-line therapeutic alternative for treatment of ASD and PFO. During the past few decades, the development of biodegradable occlusion devices has become a promising direction for transcatheter closure of ASD/PFO due to their biodegradability and improved biocompatibility. The purpose of this review is to comprehensively summarize biodegradable ASD/PFO occlusion devices, regarding device design, materials, biodegradability, and evaluation of animal or clinical experiments (if available). The current challenges and the research direction for the development of biodegradable occluders for congenital heart defects are also discussed.

Biological Scaffolds for Congenital Heart Disease

Congenital heart disease (CHD) is the most predominant birth defect and can require several invasive surgeries throughout childhood. The absence of materials with growth and remodelling potential is a limitation of currently used prosthetics in cardiovascular surgery, as well as their susceptibility to calcification. The field of tissue engineering has emerged as a regenerative medicine approach aiming to develop durable scaffolds possessing the ability to grow and remodel upon implantation into the defective hearts of babies and children with CHD. Though tissue engineering has produced several synthetic scaffolds, most of them failed to be successfully translated in this life-endangering clinical scenario, and currently, biological scaffolds are the most extensively used. This review aims to thoroughly summarise the existing biological scaffolds for the treatment of paediatric CHD, categorised as homografts and xenografts, and present the preclinical and clinical studies. Fixation as well as techniques of decellularisation will be reported, highlighting the importance of these approaches for the successful implantation of biological scaffolds that avoid prosthetic rejection. Additionally, cardiac scaffolds for paediatric CHD can be implanted as acellular prostheses, or recellularised before implantation, and cellularisation techniques will be extensively discussed.

Three-Dimensional Virtual and Printed Prototypes in Complex Congenital and Pediatric Cardiac Surgery-A Multidisciplinary Team-Learning Experience

Three-dimensional (3D) virtual modeling and printing advances individualized medicine and surgery. In congenital cardiac surgery, 3D virtual models and printed prototypes offer advantages of better understanding of complex anatomy, hands-on preoperative surgical planning and emulation, and improved communication within the multidisciplinary team and to patients. We report our single center team-learning experience about the realization and validation of possible clinical benefits of 3D-printed models in surgical planning of complex congenital cardiac surgery. CT-angiography raw data were segmented into 3D-virtual models of the heart-great vessels. Prototypes were 3D-printed as rigid "blood-volume" and flexible "hollow". The accuracy of the models was evaluated intraoperatively. Production steps were realized in the framework of a clinical/research partnership. We produced 3D prototypes of the heart-great vessels for 15 case scenarios (nine males, median age: 11 months) undergoing complex intracardiac repairs. Parity between 3D models and intraoperative structures was within 1 mm range. Models refined diagnostics in 13/15, provided new anatomic information in 9/15. As a team-learning experience, all complex staged redo-operations (13/15; Aristotle-score mean: 10.64 ± 1.95) were rehearsed on the 3D models preoperatively. 3D-printed prototypes significantly contributed to an improved/alternative operative plan on the surgical approach, modification of intracardiac repair in 13/15. No operative morbidity/mortality occurred. Our clinical/research partnership provided coverage for the extra time/labor and material/machinery not financed by insurance. 3D-printed models provided a team-learning experience and contributed to the safety of complex congenital cardiac surgeries. A clinical/research partnership may open avenues for bioprinting of patient-specific implants.

A Brief Review on Additive Manufacturing of Polymeric Composites and Nanocomposites

In this research article, a mini-review study is performed on the additive manufacturing (AM) of the polymeric matrix composites (PMCs) and nanocomposites. In this regard, some methods for manufacturing and important and applied results are briefly introduced and presented. AM of polymeric matrix composites and nanocomposites has attracted great attention and is emerging as it can make extensively customized parts with appreciably modified and improved mechanical properties compared to the unreinforced polymer materials. However, some matters must be addressed containing reduced bonding of reinforcement and matrix, the slip between reinforcement and matrix, lower creep strength, void configurations, high-speed crack propagation, obstruction because of filler inclusion, enhanced curing time, simulation and modeling, and the cost of manufacturing. In this review, some selected and significant results regarding AM or three-dimensional (3D) printing of polymeric matrix composites and nanocomposites are summarized and discuss. In addition, this article discusses the difficulties in preparing composite feedstock filaments and printing issues with nanocomposites and short and continuous fiber composites. It is discussed how to print various thermoplastic composites ranging from amorphous to crystalline polymers. In addition, the analytical and numerical models used for simulating AM, including the Fused deposition modeling (FDM) printing process and estimating the mechanical properties of printed parts, are explained in detail. Particle, fiber, and nanomaterial-reinforced polymer composites are highlighted for their performance. Finally, key limitations are identified in order to stimulate further 3D printing research in the future.