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Three-dimensional(3D)extrusion-based bioprinting is widely used in tissue engineering and regener-ative medicine to create cell-incorporated constructs or scaffolds based on the extrusion technique.One critical issue in 3D extrusion-based bioprinting is printability or the capability to form and maintain reproducible 3D scaffolds from bioink(a mixture of biomaterials and cells).Research shows that printability can be affected by many factors or parameters,including those associated with the bioink,printing process,and scaffold design,but these are far from certain.This review highlights recent de-velopments in the printability assessment of extrusion-based bioprinting with a focus on the definition of printability,printability measurements and characterization,and printability-affecting factors.Key issues and challenges related to printability are also identified and discussed,along with approaches or strategies for improving printability in extrusion-based bioprinting.
RESUMO
Abstract Background: The influence of pulmonary vein (PV) anatomy on cryo kinetics during cryoballoon (CB) ablation is unclear. Objective: To investigate the relationship between PV anatomy and cryo kinetics during CB ablation for atrial fibrillation (AF). Methods: Sixty consecutive patients were enrolled. PV anatomy, including ostial diameters (long, short and corrected), ratio between short and long diameters, ostium shape (round, oval, triangular, and narrow), and drainage pattern (typical, with common trunk, common antrum, ostial branch and supernumerary PV) were evaluated on multi-detector computed tomography (MDCT) images pre-procedure. Cryo kinetics parameters [balloon freeze time from 0 to -30ºC (BFT), balloon nadir temperature (BNT) and balloon warming time from -30 to +15ºC (BWT)] were recorded during procedure. All p values are two-sided, with values of p < 0.05 considered to be statistically significant. Results: 606 times of freezing cycle were accomplished. Moderate negative correlation was documented between BNT and corrected PV diameter (r = -0.51, p < 0.001) when using 23-mm CBs, and mild negative correlation (r = - 0.32, p = 0.001) was found when using 28-mm CBs. Multivariate logistic regression analysis revealed that PV corrected ostial diameter (OR, 1.4; p = 0.004) predicted a BNT < -51ºC when using 23-mm CBs, while PV ostium oval shape (OR, 0.3; p = 0.033) and PV locations (left inferior PV: OR, 0.04; p = 0.005; right superior PV: OR, 4.3; p = 0.025) predicted BNT < -51ºC when using 28-mm CBs. Conclusions: MDCT can provide PV anatomy accurate evaluation prior CB ablation. PV anatomy is associated with cryo kinetics during ablation.
Resumo Fundamentos: A influência da anatomia da veia pulmonar (VP) na criocinética durante a ablação por criobalão (CB) não está clara. Objetivo: Investigar a relação entre a anatomia da VP e a criocinética durante a ablação com CB para fibrilação atrial (FA). Métodos: sessenta pacientes consecutivos foram matriculados. Foram avaliados em imagens de tomografia computadorizada multidetectora (TCMD) pré-procedimento a anatomia da VP, incluindo diâmetros dos óstios (longo, curto e corrigido), relação entre diâmetros curtos e longos, forma do óstio (redondo, oval, triangular e estreito) e padrão de drenagem (típico, com tronco comum, antro comum, ramo ostial e VP supranumerária). Os parâmetros criocinéticos [tempo de congelamento de balão de 0 a -30ºC (TCB), temperatura do nadir do balão (TNB) e tempo de aquecimento do balão de -30 a + 15ºC (TAB)] foram registrados durante o procedimento. Todos os valores de p são bicaudais, com valores de p < 0,05 considerados estatisticamente significativos. Resultados: o ciclo de congelamento foi realizado 606 vezes. Correlação negativa moderada foi documentada entre o TNB e o diâmetro VP corrigido (r = - 0,51, p < 0,001) ao usar CBs de 23 mm e correlação negativa leve (r = - 0,32, p = 0,001) foi encontrada ao usar 28- mm CBs. A análise de regressão logística multivariada revelou que o diâmetro corrigido do óstio da VP (OR, 1,4; p = 0,004) previu um TNB < -51ºC ao usar CB de 23 mm, enquanto a forma oval do óstio VP (OR, 0,3; p = 0,033) e as localizações da VP (VP inferior: OR, 0,04; p = 0,005; VP superior direito: OR, 4,3; p = 0,025) previram TNB < -51ºC ao usar CBs de 28 mm. Conclusões: A TCMD pode fornecer uma avaliação precisa da anatomia da VP antes da ablação por CB. A anatomia da VP está associada à criocinética durante a ablação.