Congenital tracheal stenosis (CTS) is a rare but potentially life-threatening disease which results in congnital airway lesion. CTS is often associated with cardiovascular anomalies and presented with a wide spectrum of symptoms. CTS has challenged pediatric surgeons for decades. Various classic approaches and new techniques, including computational fluid dynamics, tissue-engineering trachea, and 3D printing have been proposed for diagnosis and treatment of CTS. This review provides a snapshot of the main progress of diagnosis and treatment of CTS.
Objective To optimize the hemodynamics of a disk blood pump in children. Method We used the computational fluid dynamics technology to simulate the flow in a pediatric blood pump numerically, and finally analyzed the results for deep study about the thrombosis and hemolysis produced in it, to improve the design according to the results of the flow field analysis. Results We calculated results between the flow rate and the pressure elevation at different rotational speed: 2 500 rpm, 3 000 rpm, and 4 000 rpm, respectively. Under each rotational speed, it was selected five different discharge outlet boundary conditions. The simulation results conformed to the experimental data. The increased pressure of the blood pump was effective. But the phenomenon of flow separation was increased the at blade surface in the low speed region. The maximum wall shear stress was maintained within 100 Pa. Conclusion The design of disc blood pump has a good fluid dynamic performance. And the flow line is fluent, the probability of thrombosis and hemolysis occurred is in the range of control. But the phenomenon of flow separation is appeared. There is a room to improve.
ObjectiveTo investigate the effects of a self-powered conduit in different patients’ models who underwent extracardiac Fontan procedure.MethodsFour children who underwent extracardiac Fontan procedure in Shanghai Children's Medical Center from 2011 to 2017 year were selected. Venae cavae and pulmonary arteries were reconstructed using Mimics 19.0®. In silico, a venturi conduit was introduced to the anastomosis of venae cavae and pulmonary artery. Then computational fluid dynamics simulation was performed using patients’ clinical data.ResultsWhen inferior venae cavae were directly to or to the left of superior venae cavae, the venturi conduit could assist the return of venous blood and reduce the pressures of venae cavae about 0.5 mm Hg. And the pressure differences between venae cavae and pulmonary arteries were about –0.7 mm Hg, which suggested that the conduit could generate right ventricle-like effect.ConclusionThe venturi conduit can reduce the pressure of venae cavae, increase pulmonary circulation flow and improve Fontan hemodynamics.
ObjectiveTo review the advances in the computational fluid dynamics (CFD) in tissue engineering.MethodsThe latest research of CFD applied to tissue engineering were extensively retrieved and analyzed, the optimization of bioreactor design and the simulation of fluid dynamics and cell growth kinetics during tissue regeneration in vitro were mainly reviewed.ResultsThe simulation and predictive capabilities of CFD can provide important guidance for the optimization of bioreactor design, and the cultivation of engineering tissue. The accuracy of model prediction results can be further improved by combining with experimental research.ConclusionAs a new and effective research tool, CFD has its unique advantages in the application of tissue engineering. However, a more comprehensive and accurate simulation of the whole process of tissue regeneration still needs further studies.
ObjectiveTo investigate the application of computational fluid dynamics (CFD) in hemodynamic evaluation of aortic root reconstruction.MethodsThe clinical data of 1 patient with severe aortic valve stenosis was analyzed. Enhanced CT images were used as the original data, and professional software was used to reconstruct the three-dimensional (3D) model and fluid mechanics simulation of the aorta (including preoperative, postoperative and ideal conditions).ResultsThe 3D reconstruction model could directly present the distribution of valve calcification and the dilatation of the ascending aorta. The remodeled sinotubular junction and sinus structure were observed in the model under postoperative and ideal conditions. The improvement of ascending aorta dilatation was evaluated statistically by the diameter distribution before and after surgery. CFD simulation showed that the area of high flow velocity, pressure intensity and wall shear stress before surgery were consistent with the expansion area of the ascending aorta, and the restricted blood flow acceleration was observed at the angle between the arch and the descending aorta. In the ideal condition, the streamline of blood at the descending aorta was more stable and flat compared with preoperative or postoperative conditions, and there was no obvious abnormal high pressure and high wall shear stress area in the ascending aorta. The cardiopulmonary bypass time was 106 min, of which the aortic cross-clamp time was 60 min. The cardiac echocardiography indicated that the aortic valve worked well, and the peak systolic blood velocity was 1.7 m/s. The length of hospital stay after surgery was 12 d, including 2 d in ICU. The ventilator use time was 11.6 h. The patient did not have any remarkable discomfort during the 1-year follow-up.ConclusionCFD can be used to evaluate anatomic and hemodynamic abnormalities before aortic root reconstruction surgery. Postoperative reconstruction simulation can be performed again to evaluate the surgical effect, and meanwhile, virtual improvement can be tried for the unresolved problems to accumulate diagnosis and treatment experience, so as to provide patients with more accurate and personalized diagnosis and treatment procedure.
Hemodynamics plays a vital role in the development and progression of cardiovascular diseases, and is closely associated with changes in morphology and function. Reliable detection of hemodynamic changes is essential to improve treatment strategies and enhance patient prognosis. The combination of computational fluid dynamics with cardiovascular imaging technology has extended the accessibility of hemodynamics. This review provides a comprehensive summary of recent developments in the application of computational fluid dynamics for cardiovascular hemodynamic assessment and a succinct discussion for potential future development.
Objective To establish a personalized Stanford type B aortic dissection numerical simulation model, and using computational fluid dynamics (CFD) numerical simulation to obtain the hemodynamic behavior and law of the type B aortic dissection at different stages of development. Methods Based on the theory of three-dimensional model reconstruction, we used CT images of a patient with type B aortic dissection in the Xiamen Cardiovascular Hospital of Xiamen University, relevant medical image processing software to reconstruct a personalized aortic three-dimensional model, and CFD to reconstruct the model which was simulated in fluid mechanics. Results The three-dimensional reconstruction model could intuitively observe the changing trend of the false cavity at different stages of the dissection development. Through fluid mechanics simulation, the blood flow rate, pressure, wall shear stress, vascular wall Von Mises stress and other parameters at different stages of the dissection development were obtained. Conclusion The hemodynamic behavior and law of relevant parameters in the development stage of aortic dissection are analyzed. The combination of the values of relevant parameters and clinical medical detection and diagnosis can well predict the development of the disease, and finally provide more theories and methods for the scientific diagnosis of aortic dissection.
The hemodynamic parameters in arteries are difficult to measure non-invasively, and the analysis and prediction of hemodynamic parameters based on computational fluid dynamics (CFD) has become one of the important research hotspots in biomechanics. This article establishes 15 idealized left coronary artery bifurcation models with concomitant stenosis and aneurysm lesions, and uses CFD method to numerically simulate them, exploring the effects of left anterior descending branch (LAD) stenosis rate and curvature radius on the hemodynamics inside the aneurysm. This study compared models with different stenosis rates and curvature radii and found that as the stenosis rate increased, the oscillatory shear index (OSI) and relative residence time (RRT) showed a trend of increase; In addition, the decrease in curvature radius led to an increase in the degree of vascular curvature and an increased risk of vascular aneurysm rupture. Among them, when the stenosis rate was less than 60%, the impact of stenosis rate on aneurysm rupture was greater, and when the stenosis rate was greater than 60%, the impact of curvature radius was more significant. Based on the research results of this article, it can be concluded that by comprehensively considering the effects of stenosis rate and curvature radius on hemodynamic parameters, the risk of aneurysm rupture can be analyzed and predicted. This article uses CFD methods to deeply explore the effects of stenosis rate and curvature radius on the hemodynamics of aneurysms, providing new theoretical basis and prediction methods for the assessment of aneurysm rupture risk, which has important academic value and practical guidance significance.