Right ventricle to pulmonary artery connection: Evolution and current alternatives

Handmade Bicuspid Valved Polytetrafluoroethylene Conduit for Right Ventricular Outflow Tract Reconstruction

Background: Excellent outcomes of right ventricle to pulmonary artery conduits with polytetrafluoroethylene (PTFE) valves have been reported. The purpose of this study was to analyze the short-term results of our handmade PTFE bicuspid valved conduit (VC) for right ventricular outflow tract reconstruction. Methods: Between September 2019 and May 2023, bicuspid PTFE-VC was implanted in 17 patients at a median age of 2.5 years (range, 3 months to 13.6 years). The PTFE-VC was fashioned from a commercially available PTFE tube graft (14 mm in three patients, 16 mm in three patients, 18 mm in one patient, 20 mm in three patients, and 22 mm in seven patients) and 0.1 mm thick PTFE membrane for the leaflet material. Valve function was assessed by echocardiogram after the implantation. The conduit reoperation and the conduit dysfunction were analyzed. There were no early deaths, but there was one late death. Results: There were no postoperative in-hospital deaths. Follow-up echocardiograms were available for 14 of 17 patients. The median follow-up was 21 months (range, 7-49 months). Conduit stenosis was none or trivial in 11 patients while it was mild in two and moderate in one patient and severe in 0 patients. Conduit insufficiency was mild or trivial in all 14 patients. By the end of the study period, freedom from reoperation/reintervention was 100%. There were no episodes of aneurysmal dilatation of the conduit or endocarditis. Conclusions: Handmade bicuspid PTFE VC shows good short-term outcome, with no significant valve dysfunction and no reintervention. A longer follow-up is necessary to evaluate the long-term advantages of using the handmade bicuspid PTFE VC.

Current development of bovine jugular vein conduit for right ventricular outflow tract reconstruction

Right ventricular outflow tract (RVOT) reconstruction is a common surgical method to treat congenital cardiac lesions, and bovine jugular vein conduit (BJVC) has become a prevalent candidate of prosthetic material for this procedure since 1999. Although many clinical studies have shown encouraging results on BJVCs, complications such as stenosis, aneurysmal dilatation, valve insufficiency, and infective endocarditis revealed in other clinical outcomes still remain problematic. This review describes the underlying mechanisms causing respective complications, and summarizes the current technological development that may address those causative factors. Novel crosslinking agents, decellularization techniques, conduit coatings, and physical reinforcement materials have improved the performances of BJVCs. The authors expect that the breakthroughs in the clinical application of BJVC may come from new genetic research findings and advanced characterization apparatuses and bioreactors, and are optimistic that the BJVC will in the future provide sophisticated therapies for next-generation RVOT reconstruction.

Dual-Gel 4D Printing of Bioinspired Tubes

The distribution of periodic patterns of materials with radial or bilateral symmetry is a universal natural design principle. Among the many biological forms, tubular shapes are a common motif in many organisms, and they are also important for bioimplants and soft robots. However, the simple design principle of strategic placement of 3D printed segments of swelling and nonswelling materials to achieve widely different functionalities is yet to be demonstrated. Here, we report the design, fabrication, and characterization of segmented 3D printed gel tubes composed of an active thermally responsive swelling gel (poly N-isopropylacrylamide) and a passive thermally nonresponsive gel (polyacrylamide). Using finite element simulations and experiments, we report a variety of shape changes including uniaxial elongation, radial expansion, bending, and gripping based on two gels. Actualization and characterization of thermally induced shape changes are of key importance to robotics and biomedical engineering. Our studies present rational approaches to engineer complex parameters with a high level of customization and tunability for additive manufacturing of dynamic gel structures.