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.
The development and progression of atherosclerosis and thrombosis are closely related to changes of hemodynamics parameters. Ultrasonic pulse wave Doppler technique is normally used for noninvasively blood flow imaging. However, this technique only provides one-dimensional velocity and depends on the angle between the ultrasound beam and the local velocity vector. In this study, ultrasonic particle image velocimetry method was used to assess whole field hemodynamic changes in normal blood vessels. By using the polynomial fitting method, we investigated the velocity gradient and assessed the shear in different blood flow velocity of 10 healthy rats. It was found that using four polynomial fitting could result in optimal measurement results. The results obtained by ultrasonic particle image velocimetry accorded with the results obtained using Doppler technique. The statistical average of cyclical vessel wall shear stress was positively related to the locational mean velocity. It is proven that ultrasonic particle image velocimetry method could be used to assess directly the real-time whole field hemodynamic changes in blood vessels and was non-invasively, and should be a good prosperous technique for monitoring complex blood flow in stenotic arteries.
Surgical intervention for chronic thoracoabdominal aortic dissecting aneurysms (cTAADA) is regarded as one of the most challenging procedures in the field of vascular surgery. For nearly six decades, open repair predominantly utilizing prosthetic grafts has been the treatment of choice for cTAADA. With advances in minimally invasive endovascular technologies, two novel surgical approaches have emerged: total endovascular stent-graft repair and hybrid procedures combining retrograde debranching of visceral arteries with endovascular stent-graft repair (abbreviated as hybrid procedure). Although total endovascular stent-graft repair offers reduced trauma and quicker recovery, limitations persist in clinical application due to hostile anatomical requirements of the aorta, high costs, and the lack of universally available stent-graft products. Hybrid repair, integrating the minimally invasive ethos of endovascular repair with visceral artery debranching techniques, has increasingly become a significant surgical modality for managing thoracoabdominal aneurysms, especially in cases unsuitable for open surgery or total endovascular treatment due to anatomical constraints such as aortic tortuosity or narrow true lumens in dissections. Recent enhancements in hybrid surgical approaches include ongoing optimization of visceral artery reconstruction strategies based on hemodynamic analyses, and exploration of the comparative benefits of staged versus concurrent surgical interventions.
Objective To investigate the clinical efficacy of mitral valve repair technique in the treatment of rheumatic mitral valve lesions. Methods The clinical data of patients diagnosed with rheumatic mitral valve lesions and undergoing mitral valve repair under extracorporeal circulation in our department from 2021 to 2022 were retrospectively analyzed. Results A total of 100 patients were collected, including 78 females and 22 males with an average age of 52 years. There were no secondary open heart or death in the whole group. Extracorporeal circulation time was 136.3±33.1 min, aortic cross-clamping time was 107.6±27.5 min, ventilator use time was 12.9±5.9 h, ICU stay was 2.6±1.4 d, and vasoactive medication use was 823.4±584.4 mg. Before and after the surgery, there were statistical differences in the left ventricular end diastolic diameter, left atrial end systolic diameter, effective mitral valve orifice area, shortening rate of left ventricular short axis, mitral E-peak blood flow velocity, mean mitral transvalvular pressure difference, mitral pressure half-time, and cardiac function graded by New York Heart Association (P＜0.05). While there was no statistical difference in left ventricular ejection fraction or left ventricular end-diastolic volume (P>0.05). Conclusion Overall repair of rheumatic mitral valve lesions can significantly improve the cardiac function and hemodynamics of the patients, and is a good choice for patients with rheumatic mitral valve lesions.
This paper aims to explore the feasibility of building a finite element model of left atrial diverticulum (LAD) using reverse engineering software based on computed tomography (CT) images. The study was based on a three-dimensional cardiac CT images of a atrial fibrillation patient with LAD. The left atrium and LAD anatomical features were accurately reproduced by using Geomagic Studio 12 and Mimics 15 reverse engineering software. In addition, one left atrial model with LAD and one without LAD were created with ANSYS finite element analysis software, and the validity of the two models were verified. The results show that it is feasible to establish the LAD finite element model based on cardiac three-dimensional CT images using reverse engineering software. The results of this paper will lay a theoretical foundation for further hemodynamic analysis of LAD.
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.
Intravascular optical coherence tomography (IVOCT) has emerged as a high-resolution and minimal-invasive imaging technique that provides high-speed visualization of coronary arterial vessel walls and clearly displays the vessel lumen and lesions under the intima. However, morphological gray-scale images cannot provide enough information about the tissue components to accurately characterize the plaque tissues including calcified, fibrous, lipidic and mixed plaques. Quantitative IVOCT (qIVOCT) is necessary to provide the physiological contrast mechanisms and obtain the characteristic parameters of tissues with clinical diagnostic value. In this paper, the progress of qIVOCT is reviewed. The current methods for quantitatively measuring optical, elastic and hemodynamic parameters of vessel wall and plaque tissues using IVOCT gray-scale images and raw backscattered signals are introduced and potential development is forecast.
Objective To investigate and compare the effects of succinylated gelatin injection and saline priming on the first hour blood pressure in critically ill patients receiving continuous renal replacement therapy (CRRT). Methods Inpatients who received continuous venous-venous dialysis filtration therapy in the intensive care unit of West China Hospital of Sichuan University between January and May 2024 were selected. The patients were randomly divided into an experimental group (colloidal solution group) and a control group (crystalloid solution group) in a 1∶1 ratio. The colloidal solution group used succinylated gelatin injection as the priming solution, and used the dual connection method to draw blood to the machine. The patient’s systolic blood pressure, diastolic blood pressure, mean arterial pressure and heart rate at 10 minutes before and 0, 1, 3, 5, 10, 30 and 60 minute after CRRT initiation, the name and dosage of vascular compression drugs pumped intravenously at 0, 30 and 60 minutes, and the liquid inlet and outlet in the first hour were monitored and recorded. The crystalloid solution group used normal saline as the priming solution, and the rest of the methods were the same as those of the colloidal solution group. Two groups of patients were compared for changes in blood pressure and heart rate during the first hour of CRRT, as well as the incidence of hypotension. Results A total of 208 patients were included, with 104 cases in each group. There was no significant difference in baseline data between the two groups (P>0.05). At 3 minutes after CRRT, the systolic blood pressure of the crystalloid solution group was lower than that of the colloidal solution group [(122.56±23.82) vs. (129.43±25.46) mm Hg (1 mm Hg=0.133 kPa); t=−2.005, P=0.046]. There was no statistically significant difference in diastolic blood pressure, mean arterial pressure, or heart rate between the two groups at different time points (P>0.05). The intra group comparison results showed that the systolic blood pressure of the crystalloid solution group decreased compared to before at 1, 3, 5, and 10 minutes after CRRT (P<0.05), while the diastolic blood pressure and mean arterial pressure decreased compared to before at 3, 5, and 10 minutes after the start of CRRT (P<0.05); there was no statistically significant difference in blood pressure of the colloidal solution group among different time points after the start of CRRT (P>0.05). The heart rate of the crystalloid solution group was higher at 10 minutes after the start of CRRT than at 3 minutes after CRRT (P=0.045); 60 minutes after the start of CRRT, the heart rate in the colloidal solution group was lower than that 0 minutes after CRRT (P=0.032); there was no statistically significant difference between the two groups at other time points within each group (P>0.05). On the first hour of CRRT, there was a statistically significant difference in the incidence of hypotension between the two groups [33 cases (31.7%) vs. 18 cases (17.3%); χ2=5.845, P=0.016]. Conclusions The use of colloidal solution pre-flushing is more advantageous to improving the decrease in blood pressure in the first hour of CRRT in severe patients than crystalloid solution group pre-flushing. And it can reduce the incidence of hypotension in the first hour of CRRT in severe patients.
ObjectiveTo explore the hemodynamic effects of inhaled nitric oxide (iNO) on postoperative hemodynamic in patients with cyanotic congenital heart disease (CHD) combined with decreased pulmonary blood flow.MethodsFrom 2014 to 2018, there were 1 764 patients who received corrective repair of cyanotic CHD with decreased pulmonary blood flow in the Department of Pediatric Cardiac Surgery of Fuwai Hospital. We included 61 patients with the ratio of right ventricular systolic pressure to systolic blood pressure (SBP) ≥75% after weaning from cardiopulmonary bypass. There were 41 males and 20 females, with the age of 20.5 (9.0, 39.0) months and weight of 12.5±7.8 kg. The patients were divided into two groups: a conventional group (33 patients, conventional therapy only) and a combined therapy group (28 patients, iNO combined with conventional therapy). The hemodynamics during the first 24 hours after iNO therapy and the in-hospital outcomes of the two groups were investigated and compared.ResultsThere was no statistical difference between the two groups in demographic characteristics and surgical parameters (P>0.05). The hemodynamic effects of iNO within 24 hours included the decrease in the vasoactive inotropic score (VIS, 21.6±6.6 vs. 17.3±7.2, P=0.020) along with the increase in blood pressure (SBP: 73.7±9.7 mm Hg vs. 90.8±9.1 mm Hg, P<0.001) , the decrease in central venous pressure (10.0±3.1 mm Hg vs. 7.9±2.1 mm Hg, P=0.020), the decrease in lactate (2.2±1.7 mmol/L vs. 1.2±0.5 mmol/L, P<0.001) and increase in urine output [2.8±1.7 mL/(kg·h) vs. 4.9±2.2 mL/(kg·h), P<0.001]. The decrease of VIS at 24 h after the surgery in the conventional therapy group was not statistically significant (22.1±7.9 vs. 20.0±8.5, P=0.232). Besides, we discovered that the need for renal replacement therapy (RRT) was less in the combined therapy group than that in the conventional therapy group, especially in the moderate complicated surgery [risk adjustment in congenital heart surgery (RACHS-1) ≤3] subgroup (9.5% vs. 40.7%, P=0.016).ConclusionIn pediatric patients after corrective repair of cyanotic and pulmonary blood follow decreased CHD with increased pulmonary vascular resistance, iNO combined with conventional therapy can improve the hemodynamics effectively. Compared with the conventional therapy, the combined therapy with iNO can decrease the VIS and the need for RRT, which is beneficial to the postoperative recovery of patients.
Vena cava filter is a filter device designed to prevent pulmonary embolism caused by thrombus detached from lower limbs and pelvis. A new retrievable vena cava filter was designed in this study. To evaluate hemodynamic performance and thrombus capture efficiency after transplanting vena cava filter, numerical simulation of computational fluid dynamics was used to simulate hemodynamics and compare it with the commercialized Denali and Aegisy filters, and in vitro experimental test was performed to compare the thrombus capture effect. In this paper, the two-phase flow model of computational fluid dynamics software was used to analyze the outlet blood flow velocity, inlet-outlet pressure difference, wall shear stress on the wall of the filter, the area ratio of the high and low wall shear stress area and thrombus capture efficiency when the thrombus diameter was 5 mm, 10 mm, 15 mm and thrombus content was 10%, 20%, 30%, respectively. Meanwhile, the thrombus capture effects of the above three filters were also compared and evaluated by in vitro experimental data. The results showed that the Denali filter has minimal interference to blood flow after implantation, but has the worst capture effect on 5 mm small diameter thrombus; the Aegisy filter has the best effect on the trapping of thrombus with different diameters and concentrations, but the low wall shear stress area ratio is the largest; the new filter designed in this study has a good filtering and capture efficiency on small-diameter thrombus, and the area ratio of low wall shear stress which is prone to thrombosis is small. The low wall shear stress area of the Denali and Aegisy filters is relatively large, and the risk of thrombosis is high. Based on the above results, it is expected that the new vena cava filter designed in this paper can provide a reference for the design and clinical selection of new filters.