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.
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 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.
Quantitative measurement of strain distribution of arterial vessel walls due to pulsatile blood flow within the vascular lumen is valuable for evaluating the elasticity of arterial wall and predicting the evolution of plaques. The present paper shows that the three-dimensional (3D) strain distribution are estimated through uni-directional coupling for 3D vessel and blood models reconstructed from intravascular ultrasound (IVUS) images with the computational fluid dynamics (CFD) numerical simulation technique. The morphology of vessel wall and plaques as well as strain distribution can be visually displayed with pseudo-color coding.
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.
To visualize and quantify the hemodynamics in the aortic arch in normal individuals, we used velocity distribution, retrograde flow, vortex formation, and mean energy loss (mEL) at different cardiac cycles in our study. We performed Vector flow mapping (VFM) analysis by using echocardiography in 87 healthy volunteers. The results showed that ① in different sections of the aortic arch, a skewed peak flow velocity (Vp) always appeared in the period of rapid ejection but in different distribution. The systolic flow in the entire aortic arch rose rapidly from near-zero at the point of iso-volumetric contraction to the peak velocity at the period of rapid ejection, and then decreased gradually; ② In the period of iso-volumetric relaxation, retrograde flow and vortex were observed in all subjects in the inner wall of the entire aortic arch; and ③ The change rule of mEL in the entire aortic arch was similar to that of flow velocity. VFM can provide insights into the intra-aortic arch flow patterns, and offer essential fundamentals about flow features associated with common aortic diseases.
Objective To explore the hemodynamic assessment after radical surgery in children with tetralogy of Fallot (TOF) by both echocardiography and Mostcare monitor. Methods Clinical data of 63 children with TOF who underwent radical surgery in our hospital from February 2016 to June 2018 were retrospectively analyzed, including 34 males and 29 females, aged 6-24 (9.82±5.77) months. There were 19 patients undergoing transannular patch reconstruction of the right ventricular outflow tract (a transannular patch group) while 44 patients retained the pulmonary valve annulus (a non-transannular patch group) . The echocardiography and Mostcare monitor parameters were recorded and brain natriuretic peptide was tested at the time points of 0, 8, 12, 24 and 48 hours after operation (T 0, T 1, T 2, T 4) to analyze their correlations and the change trend at different time points after radical surgery. Results The left ventricular ejection fraction at T 1 (43.49%±3.82%) was lower than that at T 0 (48.29%±4.55%), T 2 (45.83%±3.69%), T 3 (53.76%±4.43%) and T 4 (60.54%±3.23%, P<0.05). The cardiac index at T 1 (1.85±0.35 L·min−1·m−2) was lower than that at T 0 (2.11±0.38 L·min−1·m−2), T 2 (2.07±0.36 L·min−1·m−2), T 3 (2.42±0.37 L·min−1·m−2) and T 4 (2.82±0.42 L·min−1·m−2, P<0.05). The cardiac circulation efficiency at T1 (0.19±0.05) was lower than that at T 0 (0.22±0.06), T 2 (0.22±0.05), T 3 (0.28±0.06) and T 4 (0.34±0.06, P<0.05). The right ventricular two-chambers view fraction area change at T 1 (23.17%±3.11%) was lower than that at T 0 (25.81%±3.74%), T 2 (25.38%±3.43%), T 3 (30.60%±4.50%) and T 4 (36.94%±5.85%, P<0.05). The pulse pressure variability was the highest at T 0 (18.76%±3.58%), followed by T 1 (14.81%±3.32%), T 2 (12.44%±2.94%), T 3 (10.39%±2.96%) and T 4 (9.18%±1.92%, P<0.05). The blood brain natriuretic peptide was higher at T 1 (846.67±362.95 pg/ml) than that at T 0 (42.60±18.06 pg/ml), T 2 (730.95±351.09 pg/ml), T 3 (510.98±290.39 pg/ml) and T 4 (364.41±243.56 pg/ml, P<0.05). There was no significant difference in left ventricular ejection fraction, cardiac circulation efficiency and heart index between the two groups (P>0.05). The right ventricular two-chambers view fraction area change of the transannular patch group was significantly lower than that of the non-transannular patch group at each time point (P<0.05). The blood brain natriuretic peptide and pulse pressure variability of the transannular patch group were significantly higher than those of the non-transannular patch group (P<0.05). Left ventricular ejection fraction was positively correlated with cardiac index (r=0.637, P=0.001) and cardiac circulation efficiency (r=0.462, P=0.001) while was significantly negatively correlated with blood brain natriuretic peptide (r=–0.419, P=0.001). Conclusion Both methods can accurately reflect the state of cardiac function. Mostcare monitor has a good consistency with echocardiography. Using transannular patch to recontribute right ventricular outflow tract in operation has more influence on right ventricular systolic function. The Mostcare monitor can guide the hemodynamic management after surgery in real time, continuously and accurately.
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.
Objective To study the hemodynamic characteristics of concealed perforator flap in mini-pigs by ultrasonic Doppler technique. Methods Seven 7-month-old mini-pigs, weighing 20-25 kg, were included in the study. The saphenous artery perforator flap (group A, n=4), saphenous artery concealed perforator flap (group B, n=5), and saphenous artery concealed perforator flap combined with sarcolemma (group C, n=5) models were established randomly on both hind limbs of pigs. The pigs and flap survival conditions were observed after operation. The percentage of flap survival area was calculated by Photoshop CS5 software at 5 days after operation. Ultrasonic Doppler technique was performed on the flaps before operation and at immediate, 3 days, and 5 days after operation to record the hemodynamic changes of the flaps. The hemodynamic indicators of saphenous artery (inner diameter, peak systoli velocity, resistance index, and blood flow) and saphenous vein (inner diameter, maximum velocity, and blood flow) were recorded. Results At 1 day after operation, 1 pig died of infection, and the rest survived until the experiment was completed. Finally, the 3 flaps of group A, 4 of group B, and 5 of group C were included in the study. The flaps of the 3 groups all showed swelling after operation, which was most significant at 3 days. At 3 days after operation, the flaps in group B showed partial bruising and necrosis. At 5 days after operation, the flaps in groups A and C were basically alive, and the necrosis area of flap in group B increased further. The percentage of flap survival area in groups A, B, and C were 99.7%±0.5%, 74.8%±26.4%, and 100%, respectively. The percentage of flap was significantly lower in group B than in groups A and C (P<0.05). There was no significant difference between groups A and C (P>0.05). There were significant differences in the hemodynamic indicators of saphenous artery and vein between different time points in 3 groups (P<0.05). There was no significant difference in each indicator between groups at each time point (P>0.05). Conclusion Both the saphenous artery concealed perforator flap and the flap combined with sarcolemma have stable blood flow, but the survival area of the latter was better than the former.
Objective To evaluate the early clinical outcomes of the Renatus® balloon-expandable valve in the treatment of severe aortic stenosis. MethodsFrom November 2021 to April 2022, a total of 38 patients who received Renatus® balloon-expandable valve for severe aortic stenosis in Guangdong Provincial People's Hospital were included. There were 22 males and 16 females, with an average age of 73.7±5.3 years. Mean aortic gradient and peak aortic jet velocity at baseline, post-procedure, and follow-up were compared. Clinical outcomes including all-cause mortality, perivalvular leakage, serious adverse cardiovascular events and the occurrence of permanent pacemaker implantation were assessed. ResultsAll patients completed the procedure successfully without conversion to thoracotomy or perioperative death. The post-implant mean aortic pressure gradient was decreased from 41.5 (27.8, 58.8) mm Hg to 6.0 (3.0, 8.0) mm Hg, and the peak aortic jet velocity was also decreased from 4.1±0.9 m/s to 1.7±0.4 m/s (P<0.001). Pacemakers were required in 2 (5.3%) patients. The median follow-up time was 27.5 (23.0, 87.5) d, with a follow-up rate of 100.0%. The mean aortic gradient was 8.0 (7.0, 10.8) mm Hg and peak aortic jet velocity was 2.0±0.3 m/s, showing significant improvement compared with those in the preoperative period (P<0.001). No severe aortic regurgitation or paravalvular leak was observed. There was no serious cardiovascular adverse event or reoperative event during the study period. ConclusionTranscatheter aortic valve replacement with the domestic Renatus® balloon-expandable valve system is a safe and effective procedure for selected patients with severe aortic stenosis who are at high risk or not candidates for surgical aortic valve replacement.