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 effects of intravenous treprostinil in different doses on the hemodynamics and postoperative outcomes after high-risk total cavo-pulmonary connection (TCPC). MethodsFrom 2018 to 2021, among 189 patients who underwent TCPC in the Department of Pediatric Cardiac Surgery of Fuwai Hospital, 26 high-risk patients who received the intravenous treprostinil therapy were retrospectively analyzed. There were 12 males and 14 females, with an age of 4 (3, 6) years and a weight of 17.6±6.2 kg. The patients were divided into two groups: a high-dose group [15 patients, maintaining dose>10 ng/(kg·min)] and a low-dose group [11 patients, maintaining dose≤10 ng/(kg·min)]. The hemodynamics before treprostinil using and during the first 24 hours after reaching the maintaining dose of treprostinil, and postoperative outcomes of the two groups were investigated. ResultsThe incidence of heterotaxia was higher in the high-dose group (66.7% vs. 18.2%, P=0.021). During the observation period, the mean pulmonary artery pressure decreased from 11.9±3.6 mm Hg to 11.0±3.3 mm Hg in the low-dose group (P=0.013), and from 12.9±4.7 mm Hg to 10.2±3.4 mm Hg in the high-dose group (P=0.001). The decreasing effect in the high-dose group was better than that in the low-dose group (P=0.010). There was no statistical difference in the postoperative outcomes between the two groups (P>0.05). In terms of side effects, patients needed temporarily increased dosage of vasoactive drugs to maintain stable blood pressure during 6-12 h after treprostinil therapy in the high-dose group. ConclusionIn patients after high-risk TCPC, intravenous high-dose treprostinil has a better therapeutic effect on reducing pulmonary artery pressure. However, it should be noted that increased dosage of vasoactive agents may be required to maintain blood pressure stability in patients with high-dose treprostinil.
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.
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.
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.
Ankle pump exercise (APE) is one of the basic measures to prevent the formation of deep vein thrombosis, which has been widely recognized for its advantages of simplicity, safety, and ease of perform. However, there is still controversy regarding the frequency, duration, angle, position, and adjunctive exercise of APE. This article will review the hemodynamic and hemorheological effects of APE for the prevention of DVT, the current status of clinical application, and new advances in adjunctive APE, in order to provide methods and guidance for clinical staff.
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.
Computational fluid dynamics was used to investigate the effect of the pathogenesis of membranous obstruction of inferior vena cava of Budd-Chiari syndrome with various angles between right hepatic vein and inferior vena cava. Mimics software was used to reconstruct the models from magnetic resonance imaging (MRI) angiograms of inferior vena cava, right hepatic vein, middle hepatic vein and left hepatic vein, and 3DMAX was used to construct the models of 30°, 60°, 90° and 120° angles between right hepatic vein and inferior vena cava, which was based on the reconstructed models.The model was conducted with clinical parameters in terms of wall shear stress distribution, static pressure distribution and blood velocity. The results demonstrated that the differences between wall shear stress and static pressure had statistical significance with various angles between right hepatic vein and inferior vena cava by SPSS. The pathogenesis of membranous obstruction of inferior vena cava had a correlation with the angles between right hepatic vein and inferior vena cava.
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.
Objective To investigate the correlation of intracranial arachnoid cyst (IAC) with epilepsy and the possible mechanism of seizure induced by IAC. Methods Patients with IAC, who were treated in West China Hospital of Sichuan University between January 2009 and January 2019, were included and divided into IAC with epilepsy group and IAC without epilepsy group according to whether they were diagnosed with epilepsy. We collected the IAC location information of all subjects after the establishment of a three-dimensional spatial coordinate system of MRI images. Computational fluid dynamics technology was used to establish a blood vessel model in cyst area and perform hemodynamic analysis basing on contrast-enhanced CT images. Results A total of 72 patients were enrolled, including 24 in the IAC with epilepsy group and 48 in the IAC without epilepsy group. There was no significant difference between the two groups in terms of sex, age, IAC location, the volumes or the maximum diameters of IAC (P>0.05). Consecutive areas formed by the seven high-risk areas found in the IAC with epilepsy group were located in the temporal area. The seven high-risk areas were simultaneous IAC location in 5 patients in the IAC with epilepsy group and in 1 patient in the IAC without epilepsy group, and the difference was statistically significant (χ2=5.114, P=0.024). Comparison of the hemodynamic parameters between the two types of vascular models revealed similar pressure changes and blood pressure parameters, with lower blood flow and higher mean vascular wall shear stress in the IAC with epilepsy group. Conclusions IAC may cause epilepsy by increasing adjacent blood vessel stenosis and blood vessel wall shear stress through cyst space-occupying effect. The most common location of IAC with epilepsy is the temporal area. The occupying effect of IAC should be considered in the location of epileptogenic foci before surgery for IAC patients with epilepsy.