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Objective To investigate the effects of banding width on hemodynamic characteristics of pulmonary artery (PA) by constructing pulmonary artery banding (PAB) models with different widths. Methods Based on clinical practice, with the same banding position and degree, computer-aided design (CAD) was utilized to reconstruct three-dimensional PAB models with different banding widths (2, 3, 4, 5 mm). Hemodynamic characteristics of the models with different banding widths, including pressure, streamlines, energy loss, energy efficiency and blood flow distribution ratio, were compared and analyzed through computational fluid dynamics (CFD). Results The pressure of PA decreased significantly, while the change of banding width had no significant effects on the pressure drop level at banding position. With the increase of banding width, the energy loss decreased, and the energy efficiency showed an upward trend. The blood flow of the left PA raised, and the ratio of blood flow distribution between the left PA and right PA increased, with the maximum reaching up to 2.28 : 1. Conclusions The increase of banding width can reduce the energy loss of PA and improve the energy efficiency of blood flow, but it will lead to the imbalance of blood flow distributions between the left and right lungs. Both the balance of blood flow distribution and the energy loss should be considered in choice for banding width of PAB. The virtual design of PAB surgery based on CAD and CFD will assist individualized banding width selection in future.
ABSTRACT
Pectus excavatum is a common congenital chest wall deformities in children, presented with abnormal collapse of anterior chest wall. Thoracoscopic Nuss procedure is the present widely utilized clinical approach. Due to implanting a steel bar into the substernal area, operative organ injuries, postoperative pain, bar malposition, incomplete correction as well as risks of bar removal may occur. With the advancement of digital precision medicine and the interdisciplinary research of various disciplines and fields, there are more and more clinical applications and translations of these emerging applications represented by computational biomechanical simulations, three-dimensional printing and the latest absorbable biomaterial. They bring new opportunities and prospects for solving problems in the clinical treatment of PE as well as the improvement and development of patient-specific Nuss procedure planning.
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Objective:To investigate hemodynamic characteristics of the modified Blalock-Taussig shunt (MBTS) with the preservation or ligation of ductus arteriosus (DA) based on computational fluid dynamics (CFD), thus to help preoperative surgery design and postoperative prediction.Methods:A patient with pulmonary atresia and patent ductus arteriosus was included. Patient-specific three-dimensional model was reconstructed and virtual surgeries of shunt insertion and ductus ligation or preservation were performed via computer-aided design (CAD). CFD was utilized to analyze hemodynamic parameters preoperatively and postoperatively based on patient-specific anatomy and physiologic data.Results:The preservation of DA competitively reduced the shunt flow but increased total pulmonary perfusion. The shunt flow and ductal flow collided with each other, causing large and complicated turbulence in pulmonary artery where lower wall shear stress and higher oscillatory shear index were distributed, as well as higher energy loss.Conclusion:The preservation of DA is riskier in hemodynamics which may lead to pulmonary over-perfusion, inadequate systemic perfusion and heavier cardiac burden, thus increasing the risk of heart failure and it seems to bring no benefit in terms of reducing risks of thrombosis.
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Objective To investigate the effects of non-Newtonian properties on hemodynamic characteristics of Fontan procedure in computational simulation. Methods A Fontan vascular model was reconstructed based on patient-specific medical images. The boundary conditions were set according to velocity profiles measured by real-time echocardiography. The Newtonian model and two non-Newtonian (Casson and Carreau) models were applied to analyze the hemodynamic parameters, including flow ratio (FR), energy loss (EL), wall shear stress (WSS) as well as non-Newtonian importance factor, so as to compare flow differences between the Newtonian model and non-Newtonian models. Results The rheological models had small effects on the FR. The EL of non-Newtonian models was higher than that of the Newtonian model, and the EL of Casson model was the highest. Flow recirculation and flow disturbance accompanied with low WSS were observed in inferior vena cava (IVC). At low inflow velocity, flow disturbance in IVC of Newtonian model was more obvious. The calculations of non-Newtonian importance factor suggested significant non-Newtonian viscosity in IVC. Conclusions Non-Newtonian viscosity is significant in IVC where low velocity and flow recirculation are observed. Non-Newtonian properties of the blood should be considered in patient-specific hemodynamic simulation of Fontan procedure.
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Objective:To explore the causes of death after congenital heart surgery, which may be benefit for improving postoperative outcome of children with congenital heart disease (CHD).Methods:All cases of in-hospital mortality from 2013 to 2018 were collected to analyze the epidemiological characteristics of mortality and causes of death.Results:The mortality showed a downtrend over the past 6 years, from 2.2% in 2013 to 1.2% in 2018.Of all the cases, 72.0% children died under the age of one year old.The death mainly occurred within one week postoperatively (254, 73.2%), especially during the first (101, 29.1%) and the second (51, 14.7%) days.The main cause of death was residual or remained anatomy issues (103, 29.7%), followed by arrhythmia (66, 19.0%) and pulmonary hypertension (57, 16.4%). The incidence of heart failure ( P=0.048) and pulmonary hypertension( P<0.001) in children with functional single ventricle was higher than that in biventricular patients. Conclusion:With the progress of surgical technology and cardiopulmonary bypass, and the improvement of postoperative management, early death after the open-heart surgery for CHD decreased year by year.Postoperative residual or remained anatomy issues was the main cause of death, and the management of it should be strengthened in clinic, especially in children under one year old.