Organ-on-a-Chip (OOC) platforms are microfluidic systems that recreate key features of human organ physiology in vitro via controlled perfusion. Fluid mechanical stimuli strongly influence cell morphology and function, making this important for cardiovascular OOC applications exposed to pulsatile blood flow. However, many existing OOC devices employ relatively simple chamber geometries and steady inflow assumptions, which may cause non-uniform shear exposure to cells, create stagnant regions with prolonged residence time, and overlook the specific effects of pulsatile perfusion. Here, we used computational fluid dynamics (CFD) to investigate how chamber geometry and inflow conditions shape the near-wall flow environment on a cell culture surface at a matched cycle-averaged volumetric flow rate. Numerical results demonstrated that pillarized chambers markedly reduced relative residence time (RRT) versus the flat chamber, and the small pillar configuration produced the most uniform time-averaged wall shear stress (TAWSS) distribution among the tested designs. Phase-resolved analysis further showed that wall shear stress varies with waveform phase, indicating that steady inflow may not capture features of pulsatile perfusion. These findings provide practical guidance for pillar geometries and perfusion conditions to create more controlled and physiologically relevant microenvironments in OOC platforms, thus improving the reliability of cell experimental readouts.

Background and objective: Surgical correction of pulmonary artery stenosis (PAS) is essential to the prognosis of patients with tetralogy of Fallot (TOF). The double -patch method of pulmonary arterioplasty is usually applied in case of multiple stenosis in TOF patients' pulmonary artery (PA) and when PAS cannot be relieved by the singlepatch method. The surgical planning for the double -patch design remains challenging. The purpose of this study is to investigate the double -patch design with different angulations between the left pulmonary artery (LPA) and the right pulmonary artery (RPA), and to understand postoperative hemodynamic alterations by the application of computer -aided design (CAD) and computational fluid dynamics (CFD) techniques. Methods: The three-dimensional model of the PA was reconstructed based on preoperative computed tomography imaging data obtained from the patient with TOF. Three postoperative models with different designs of doublepatch were created by "virtual surgery" using the CAD technique. Double -Patch 120 Model was created with double patches implanted in the main pulmonary artery (MPA) and the PA bifurcation and without changing the spatial position of PA. The angulation between the LPA and the RPA was defined as theta, which equaled to 120 degrees in Pre -Operative Model and Double -Patch 120 Model. Based on Double -Patch 120 Model, Double -Patch 110 Model and Double -Patch 130 Model were generated with theta equaled to 110 degrees and 130 degrees, respectively. Combined with CFD, the differences of velocity streamlines, wall shear stress (WSS), flow distribution ratio (FDR), and energy loss (EL) were compared to analyze postoperative pulmonary flow characteristics. Results: The values of velocity and WSS decreased significantly after virtual surgery. Obvious vortices and swirling flows were observed downstream of the stenosis of RPA and LPA in Pre -Operative Model, while fewer vortices developed along the anterior wall of the expanded lumens of RPA, especially in Double -Patch 110 Model. With the relief of PAS, two relatively higher WSS regions were observed at the posterior walls of RPA and LPA. The maximum WSS values in these regions of Double -Patch 110 Model were lower than those in DoublePatch 120 Model and Double -Patch 130 Model. Furthermore, the FDRs were elevated and the ELs were greatly reduced. It was found that Double -Patch 110 Model with the angulation between the LPA and the RPA equaled to 110 degrees showed relatively better properties of hemodynamics than other models. Conclusions: The angulation between the LPA and the RPA is an important factor that should be integrated in the double -patch design for TOF repair. Virtual surgery based on patient -specific vascular model and computational hemodynamics can be used to provide assistance for individualized surgical planning of double -patch arterioplasty.

Tetralogy of Fallot (TOF) is one of the commonest cyanotic congenital heart diseases, characterized by the highly variable anatomy of pulmonary artery (PA), location and degree of obstruction. Subtle alterations in the geometry of PAs would cause changes of pulmonary hemodynamics, which are closely associated with the outcome of TOF patients. Hence, it is critical to understand the geometric characteristics of PA in TOF patients. This study was conducted to explored the differences of tortuosity of PAs between TOF patients and children with normal PAs. And there were twenty TOF patients and ten individuals with normal PA. The three-dimensional geometries of PAs were constructed based on preoperative computed tomography data. The tortuosity of pulmonary arteries were quantitatively measured and statistically analyzed. It was found that there were no obvious differences in the tortuosity of right pulmonary artery (RPA) between TOF and control groups (1.07 ± 0.044 vs. 1.07 ± 0.029, P = 0.977). Nevertheless, the tortuosity of main pulmonary artery (MPA) (1.07 ± 0.012 vs. 1.11 ± 0.038, P < 0.0001) and the tortuosity of left pulmonary artery (LPA) (1.10±0.022 vs. 1.18±0.070, P = 0.001) were relatively higher in the TOF group compared with the control group. The positive correlation was found between the tortuosity of MPA and the tortuosity of LPA (r=0.618, P < 0.0001). The area under the curve (AUC) of the MPA tortuosity and the LPA tortuosity was 0.945 and 0.935, respectively. They exhibit both high sensitivity and specificity in the diagnosis of TOF. The cutoff value of the MPA tortuosity was 1.092, and that of the LPA tortuosity was 1.117. It revealed that increased tortuosity of MPA and LPA in TOF patients compared with those of normal subjects, which might provide guidance for the diagnostic evaluation and prognostic prediction of TOF patients.

Background: The assessment of renal function is important to the prognosis of patients needing Fontan palliation due to the reconstructed compromised circulation. To know the relationship between the kidney perfusion and hemodynamic characteristics during surgical design could reduce the risk of acute kidney injury (AKI) and the postoperative complications. However, the issue is still unsolved because the current clinical evaluation methods are unable to predict the hemodynamic changes in renal artery (RA).Methods: We reconstructed a three-dimen-sional (3D) vascular model of a patient requiring Fontan palliation. The technique of computational fluid dynamics (CFD) was utilized to explore the changes of RA hemodynamics under different possible blood flow rates. The relationship between the kidney perfusion and hemodynamic characteristics was investigated.Results: The calculated results indicated the declined tendency of the pressure and pressure drop as the flow rate decreased. When the flow rate decreased to two-thirds of its baseline, both the pressure of left renal artery (LRA) and the pressure of right renal artery (RRA) dipped below 50%, and the pressure of RRA fell more quickly than that of LRA. Uneven distribution of WSS was observed on the trunk of RA, and the lowest WSS was found at the distal of RA. The average WSS in RA dropped to around 50% as the flow rate reached one-third of its baseline.Conclusions: As a promising approach, CFD can be utilized to quantitatively evaluate the hemodynamic char-acteristics of RA and contribute to offsetting the drawbacks of clinical assessments of renal function, to help rea-lize better prognosis for the patients with Fontan palliation.

目的:利用计算流体动力学探讨Fontan术后肾血流动力学变化,以辅助临床实现早期监测.方法:基于医学影像数据三维重建肾动脉分析Fontan手术前后不同时刻肾血流动力学参数差异.结果:肾动脉阻力指数及压力阶差在Fontan术后3 h较术前均增高,右肾动脉在术后3 d前均为高速流动,且术后左、右肾动脉血流动力学并未呈一致性改变.结论:计算流体动力学技术结合多普勒超声检查可为临床Fontan手术患儿早期异常肾血流动力学监测提供综合全面的评估,有助于患儿围手术期管理,改善预后.

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.

目的 利用计算流体力学方法探索肺动脉环缩术(PAB)中腔外环缩术(E-PAB)和腔内环缩术(I-PAB)间血流动力学差异.方法 纳入2020年上海交通大学医学院附属上海儿童医学中心1例需行PAB手术患儿,基于医学影像数据三维建模,利用计算机辅助设计分别行E-PAB和I-PAB虚拟手术,通过计算流体动力学分析比较术后肺动脉血流动力学参数差异.结果 与E-PAB相比,I-PAB术后环缩部位附近有更多湍流形成,该处附近压力变化明显,壁面剪切力较高,可达133Pa.I-PAB术后总能量损失(0.18W)远高于E-PAB(0.05W),能量效率32.61％,约为E-PAB的一半.结论 E-PAB在控制压力负荷,减轻心脏负担更具优势.不同环缩方式造成肺动脉几何形态差异是导致血流动力学表现不同的主要因素,计算流体动力学结合计算机辅助设计是术前手术规划和术后血流动力学预测的一种新型工具.

This study was conducted to investigate the pulmonary artery (PA) variations in tetralogy of Fallot (TOF) and preoperative morphological predictors for early reoperation. Eighty-three TOF patients and 20 children with normal PA were included. The TOF group was divided into two subsets according to whether or not reoperation was performed within 3 years postoperatively. Clinical information was obtained, along with computed tomography (CT)-based three-dimensional geometry of the PA. Morphological measurements of the length of the main PA branches, the angles between them, and the cross-sectional area of each segment of the PAs were acquired using computer software. Logistic regression and receiver operating characteristic curves were applied to analysis. The TOF group showed a significantly smaller PA size and irregular PA shape, with lower Nakata and McGoon indices, than the control group. The median bifurcation angle (angle-γ) was greater than 100° in the TOF group, as compared to 66.70° in the control group (P < 0.000). Residual obstruction of the infundibulum or PAs was the main reason for early reoperation in this series. The development of the main PA and left PA was poorer in the reoperation subset than in the non-reoperation subset (P ≤ 0.01). The preoperative angle-γ in the reoperation subset was larger than that in the non-reoperation subset (median, 117.8° vs. 112.0°, P = 0.026). Higher weight (OR = 0.372) and McGoon index (OR = 0.122) were protective factors, while larger angle-γ (> 114.8°, OR = 5.040) and angle-γ normalized by body surface area (BSA) (γ/BSA > 297.9, OR = 18.860) were risk factors. This study provides an intuitive perspective of PA anatomical variations in TOF. Larger preoperative PA bifurcation angle and γ/BSA were morphological risk predictors of postoperative reoperation in patients with TOF.

目的 探究不同开窗形状对于全腔肺动脉连接术(total cavo-pulmonary connection,TCPC)循环血流动力学的影响.方法 利用术后患儿的影像学资料重建TCPC三维模型,在面积相等的情况下分别设计圆形、正方形、椭圆形和菱形四种不同形状的开窗.以临床测量的血流动力学参数为依据设定边界条件,应用计算流体力学(computational fluid dynamics,CFD)技术分别对无开窗以及四种不同形状开窗下的血流进行模拟.结果 菱形开窗的平均壁面剪切力最低,为2.1 Pa,圆形开窗时最高,为2.7 Pa;菱形开窗的整体TCPC循环能量损失也最低,为10.94 mW,而圆形开窗最高,为13.69 mW;不同形状开窗下窗口分流量和中心静脉压等参数差异较小.结论 在面积相同的情况下,不同的开窗形状下TCPC区域的平均壁面剪切力和能量消耗均有所不同.

The question of preserving the patent ductus arteriosus (PDA) during the modified Blalock–Taussig shunt (MBTS) procedure remains controversial. The goal of this study was to investigate the effects of the PDA on the flow features of the MBTS to help with preoperative surgery design and postoperative prediction. In this study, a patient with pulmonary atresia and PDA was included. A patient-specific three-dimensional model was reconstructed, and virtual surgeries of shunt insertion and ductus ligation were performed using computer-aided design. Computational fluid dynamics was utilized to analyze the hemodynamic parameters of varied models based on the patient-specific anatomy and physiological data. The preservation of the PDA competitively reduced the shunt flow but increased total pulmonary perfusion. The shunt flow and ductal flow collided, causing significant and complicated turbulence in the pulmonary artery where low wall shear stress, high oscillatory shear index, and high relative residence time were distributed. The highest energy loss was found when the PDA was preserved. The preservation of PDA is not recommended during MBTS procedures because it negatively influences hemodynamics. This may lead to pulmonary overperfusion, inadequate systemic perfusion, and a heavier cardiac burden, thus increasing the risk of heart failure. Also, it seems to bring no benefit in terms of reducing the risk for thrombosis.

According to the actual requirements of pediatric intensive care, a suction detection system of pediatric oral secretions integrated with monitoring function is designed. The system has the function of adjustable intermittent attraction. The duration and proportion of intermittent attraction can be adjusted according to the individualized needs of pediatric intensive care. The suction head of pacifier can reduce the mechanical damage to pediatric oral mucosa as much as possible. Meanwhile, the system can detect and monitor the real-time biochemical indexes of the collected oral secretions, which can be used to help the judgement of aspiration and quantitatively evaluate the microcirculation dysfunction.

Objective: Pulmonary hypertension related to congenital heart disease (PH-CHD) is a devastating disease caused by hemodynamic disorders. Previous hemodynamic research in PH-CHD mainly focused on wall shear stress (WSS). However, energy loss (EL) is a vital parameter in evaluation of hemodynamic status. We investigated if EL of the pulmonary artery (PA) is a potential biomechanical marker for comprehensive assessment of PH-CHD. Materials and Methods: Ten PH-CHD patients and 10 age-matched controls were enrolled. Subject-specific 3-D PA models were reconstructed based on computed tomography. Transient flow, WSS, and EL in the PA were calculated using non-invasive computational fluid dynamics. The relationship between body surface area (BSA)-normalized EL (E.) and PA morphology and PA flow were analyzed. Results: Morphologic analysis indicated that the BSA-normalized main PA (MPA) diameter (DMPAnorm), MPA/aorta diameter ratio (DMPA/DAO), and MPA/(left PA + right PA) [DMPA/D(LPA+RPA)] diameter ratio were significantly larger in PH-CHD patients. Hemodynamic results showed that the velocity of the PA branches was higher in PH-CHD patients, in whom PA flow rate usually increased. WSS in the MPA was lower and E. was higher in PH-CHD patients. E. was positively correlated with DMPAnorm, DMPA/DAO, and DMPA/D(LPA+RPA) ratios and the flow rate in the PA. E. was a sensitive index for the diagnosis of PH-CHD. Conclusion: E. is a potential biomechanical marker for PH-CHD assessment. This hemodynamic parameter may lead to new directions for revealing the potential pathophysiologic mechanism of PH-CHD.

目的 先天性心脏病相关性肺动脉高压(pulmonary arterial hypertension related to congenital heart disease,PAH-CHD)是肺动脉血流动力学异常所致的一种疾病.研究肺循环血流动力学特异性,有助于了解PAH-CHD发生发展的生物力学因素.方法 对5例PAH-CHD患儿和5例无PAH (Non-PAH)的先天性心脏病患儿通过临床及影像资料收集,重建三维血管模型,利用计算流体动力学模拟肺动脉血液流动,对比分析肺动脉血流动力学相关速度流线、壁面剪切力(wall shear stress,WSS)及单位体表面积平均能量损失((E))差异.结果 血流动力学相关指标显示,PAH-CHD患儿左右肺动脉分支处流速和WSS明显升高,主肺动脉处WSS明显降低,(E)呈显著增加趋势且与肺动脉直径及入口流量呈明显正相关.结论 PAH-CHD患儿较Non-PAH患儿肺动脉分支处流速和WSS明显升高,主肺动脉WSS降低,(E)增加,表明这些血流动力学因素与PAH-CHD密切相关,是临床评估PAH-CHD的潜在血流动力学指标.

Background The desirable distance, defined as offset, between the central line of the superior vena cava (SVC) and the intra-atrial conduit after an intra-atrial conduit (IAC) Fontan's procedure remained unclear. We compared the hemodynamic features using virtual surgery with different offset designs in our study. Methods Three-dimensional models of IAC Fontan's procedure were reconstructed according to the magnetic resonance imagings (MRIs) of three patients, then four models for each patient with different offsets equaling 100, 67, 33, and 0% of the diameter of the IVC were reconstructed. Computational fluid dynamics (CFD) were performed in each model to predict the best hemodynamic features, including streamlines of blood flow, wall shear stress (WSS), energy loss (EL), and the hepatic flow distribution (HFD) ratio. Results Comprehensive evaluation of WSS, EL, and HFD revealed than an offset of 33% presents the best hemodynamic performance among the three patients modeled. In patient A, an offset of 33% resulted in the best HFD (left pulmonary artery/right pulmonary artery [LPA/RPA] = 35/65%). In patient B, the best trade-off between HFD (35/65%), and WSS was achieved with an offset of 33%. In patient C, EL peaked at an offset of 0% and significantly dropped at an offset of 33% with a desirable HFD (60/40%). Conclusions We verified that the offset distance influences hemodynamic performance in IAC Fontan's procedure. Considering several hemodynamic parameters, the best trade-offs between hemorheology, pulmonary perfusion, and energy efficiency were achieved at an offset of 33%. This distance should be taken into consideration and optimized during the surgical planning for the IAC Fontan's procedure.

目的 研究内管道Fontan手术中上腔静脉中线与心内管道中线之间(定义为Offset)的最佳距离并比较不同Offset对血流动力学的影响.方法 收集心内管道Fontan患儿术后心脏磁共振影像资料,通过三维立体建模、虚拟手术技术以及血流动力学模拟,探究不同Offset距离(相当于下腔静脉直径的0、33％、67％和100％)对血管壁剪切力、血流分布、肝血流分配比以及能量损失等血流动力学参数的影响.结果 Offset为0时,患儿左肺动脉起始段存在异常高剪切力区域;同时,在上腔静脉、心内管道连接肺动脉处存在螺旋状涡流.Offset从0至100％相对应的能量损失分别为69.96 mW、50.52 mW、58.00 mW和62.94 mW;肝血流分配(左肺动脉/右肺动脉)分别为65％:35％、60％:40％、55％:45％、55％:45％.结论 不同Offset对心内管道Fontan手术血流动力学有显著的影响.综合血管壁剪切力、血流分布、肝血流分配比以及能量损失等指标,Offset 33％为该患儿最佳Offset距离.

通过收集局限型先天性主动脉瓣上狭窄患儿术前超声心动图、CT影像资料,经三维立体建模、虚拟手术技术以及血流动力学模拟,探究先天性局限型主动脉瓣上狭窄外科纠治手术(McGoon术、Doty术以及Brom术)术后对主动脉、冠状动脉及头臂血管区域血流动力学的影响.结果显示三种手术方式术后窦管交界、升主动脉、主动脉弓内异常高速血流均消失.三种虚拟手术均能有效解除狭窄且术后各项血流动力学指标并无明显差异.McGoon手术操作相对安全简易,可作为局限型先天性瓣上狭窄手术的首选方案.

This study introduced a combined computational fluid dynamics (CFD) and echocardiography methodology to simulate blood flow in the single right ventricle (SRV) and normal ventricles to study the intraventricular flow. Derived from echocardiographic image loops, CFD-based three-dimensional (3D) flow models of normal subject's left ventricle (LV) and right ventricle (RV) and SRV with and without heart failure at three characteristic diastolic statuses were reconstructed. The CFD derived morphological and functional measurements in normal ventricles and the SRV were validated with echocardiography. The vortex in the normal ventricles and the SRV were studied. The morphological and functional measurements derived from CFD modeling and echocardiography were comparable, and both methods demonstrated the larger volume and higher spherical index in the SRV, in particular the SRV with heart failure. All the vortices in the SRV were smaller than those in the normal control subject's LV and RV, notably with heart failure. Unlike normal LV and RV, no vortex ring was observed in the SRV. Echocardiography-based CFD demonstrated the feasibility of quantifying ventricular morphology and function; in addition, CFD can detect the abnormal flow pattern (smaller or obliterated vortices) in the SRV when compared with normal ventricles.

Cavopulmonary anastomosis is a common surgical method for patients with single-ventricle. Studies found that preservation of the antegrade pulmonary blood flow (APBF) can improve postoperative arterial blood oxygen saturations. Here, a patient-specific 3D model was reconstructed as an original model. Based on it, we imitated four possible surgical models with different angulation between APBF and vertical plane of superior vena cava (SVC) to 75°, 60°, 45° and 30° by the method of computer-aided design (CAD). Local hemodynamics of the connected area were analyzed by computational fluid dynamics (CFD). The results indicated that changing the APBF will affect local hemodynamic characteristics, and the angle of APBF should be appropriately controlled in clinical practice.

Analysis of hemodynamics inside tricuspid atresia (TA) chamber is essential to the understanding of TA for optimal treatment. In this study, we introduced a combined computational fluid dynamics (CFD) to simulate blood flow in the left ventricle (LV) to study the diastolic flow changes in TA. Real-time 3-dimentional echocardiography loops (ECHO) were acquired in normal control group, in TA patients before surgery (pre-op group) and after surgery (post-op group). ECHO loops were reconstructed and simulated by CFD, the geometric, volumetric changes, and vortices in the LV were studies and compare among 3 groups. Compared with the control group, pre-op TA patients demonstrated significant LV remodeling, manifesting with smaller LV length, larger diameter, width and spherical index, as well as lager volumes; post-op TA group showed revisions in values of both geometric and volumetric measurements. CDF also demonstrated the abnormality of vortices in the pre-op TA patients and the alteration of existence and measurements of vortex in postoperation group. Echo-based CFD modeling can show the abnormality of TA in both LV geometric, volumetric measurements and intracardiac vortices; and CFD is capable to demonstrate the alterations of LV after Fontan and Glenn surgical procedure.

Objective:To investigate the morphological characteristics of pulmonary arteries in tetralogy of Fallot patients. Methods:By medical image three dimensional (3D ) reconstruction software,3D models of pulmonary arteries were reconstructed and analyzed in ten pediatric patients without pulmonary artery malformation and ten pediatric patients with tetralogy of Fallot. Results:The 3D models of normal pulmonary arteries were homogeneous,which had a″Y″shape in the top viewport, and the central line of main pulmonary artery was continued with that of left pulmonary artery.On the contrary,the pulmonary artery models of tetralogy of Fallot were remarkably different,which did′t have the normal structure homogeneity and showed the offset″Y″shape. Conclusion:The morphological characteristics of pulmonary arteries in tetralogy of Fallot patients are of great dissimilarity,which should be carefully analyzed before surgery.