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 explore the effectiveness and predictive value of computer simulated thoracic endovascular aortic repair (TEVAR). Methods The clinical data of the patients with Stanford type B aortic dissection who underwent TEVAR from February 2019 to February 2022 in our hospital was collected. According to whether there was residual false cavity around the stent about 1 week after TEVAR, the patients were divided into a false cavity closure group and a false cavity residual group. Based on computer simulation, personalized design and three-dimensional construction of the stent framework and covering were carried out. After the stent framework and membrane were assembled, they were pressed and placed into the reconstructed aortic dissection model. TEVAR computer simulation was performed, and the simulation results were analyzed for hemodynamics to obtain the maximum blood flow velocity and maximum wall shear stress at the false lumen outlet level at the peak systolic velocity of the ventricle, which were compared with the real hemodynamic data of the patient after TEVAR surgery. The impact of hemodynamics on the residual false lumen around the stent in the near future based on computer simulation of hemodynamic data after TEVAR surgery was further explored. Results Finally a total of 28 patients were collected, including 24 males and 4 females aged 53.390±11.020 years. There were 18 patients in the false cavity closure group, and 10 patients in the false cavity residual group. The error rate of shear stress of the distal decompression port of the false cavity after computer simulation TEVAR was 6%-25%, and the error rate of blood flow velocity was 3%-31%. There was no statistical difference in age, proportion of male, history of hypertension, history of diabetes, smoking history, prothrombin time or activated partial thromboplatin time at admission between the two groups (all P>0.05). The blood flow velocity and shear stress after TEVAR were statistically significant (all P<0.05). The maximum shear stress (OR=1.823, P=0.010) of the false cavity at the level of the distal decompression port after simulated TEVAR was an independent risk factor for the residual false cavity around the stent. Receiver operating characteristic curve analysis showed that the area under the curve corresponding to the maximum shear stress of false cavity at the level of distal decompression port after simulated TEVAR was 0.872, the best cross-sectional value was 8.469 Pa, and the sensitivity and specificity were 90.0% and 83.3%, respectively. Conclusion Computers can effectively simulate TEVAR and perform hemodynamic analysis before and after TEVAR surgery through simulation. Maximum shear stress at the decompression port of the distal end of the false cavity is an independent risk factor for the residual false cavity around the stent. When it is greater than 8.469 Pa, the probability of residual false cavity around the stent increases greatly.
The impeller profile, which is one of the most important factors, determines the creation of shear stress which leads to blood hemolysis in the internal flow of centrifugal blood pump. The investigation of the internal flow field in centrifugal blood pump and the estimation of the hemolysis within different impeller profiles will provide information to improve the performance of centrifugal blood pump. The SST κ-ω with low Reynolds correction was used in our laboratory to study the internal flow fields for four kinds of impellers of centrifugal blood pump. The flow fields included distributions of pressure field, velocity field and shear stress field. In addition, a fast numerical hemolysis approximation was adopted to calculate the normalized index of hemolysis (NIH). The results indicated that the pressure field distribution in all kinds of blood pump were reasonable, but for the log spiral impeller pump, the vortex and backflow were much lower than those of the other pumps, and the high shear stress zone was just about 0.004%, and the NIH was 0.0089.
The pulsatile flow experiment can not only evaluate the preclinical safety and risk of prosthetic heart valve (PHV) but also play an important role in the computational model and fluid simulation, providing an experimental basis for the performance optimization of PHV. This paper mainly reviews the development and the latest progress of PHV pulsatile flow experiments and the characteristics of experimental pulse duplicator, and discuss the research direction of pulsatile flow experiments, expecting a further development in this field.
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.
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.
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.
This paper aims to analyze the impact of splenic vein thrombosis (SVT) on the hemodynamic parameters in hepatic portal vein system. Based on computed tomography (CT) images of a patient with portal hypertension and commercial software MIMICS, the patient's portal venous system model was reconstructed. Color Doppler ultrasound method was used to measure the blood flow velocity in portal vein system and then the blood flow velocities were used as the inlet boundary conditions of simulation. By using the computational fluid dynamics (CFD) method, we simulated the changes of hemodynamic parameters in portal venous system with and without splenic vein thrombosis and analyzed the influence of physiological processes. The simulation results reproduced the blood flow process in portal venous system and the results showed that the splenic vein thrombosis caused serious impacts on hemodynamics. When blood flowed through the thrombosis, blood pressure reduced, flow velocity and wall shear stress increased. Flow resistance increased, blood flow velocity slowed down, the pressure gradient and wall shear stress distribution were more uniform in portal vein. The blood supply to liver decreased. Splenic vein thrombosis led to the possibility of forming new thrombosis in portal vein and surroundings.
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.
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.