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Karimian R, Saghafian M, Shirani E. Numerical investigation of LDL nanoparticle collision in coronary artery grafts with porous wall and different implantation angles and two state of inlet velocity. PLoS One 2024; 19:e0300326. [PMID: 38626003 PMCID: PMC11020682 DOI: 10.1371/journal.pone.0300326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2023] [Accepted: 02/23/2024] [Indexed: 04/18/2024] Open
Abstract
This study aimed to reduce the risk of graft occlusion by evaluating the two-phase flow of blood and LDL nanoparticles in coronary artery grafts. The study considered blood as an incompressible Newtonian fluid, with the addition of LDL nanoparticles, and the artery wall as a porous medium. Two scenarios were compared, with constant inlet velocity (CIV) and other with pulsatile inlet velocity (PIV), with LDL nanoparticles experiencing drag, wall-induced lift, and induced Saffman lift forces, or drag force only. The study also evaluated the concentration polarization of LDLs (CP of LDLs) near the walls, by considering the artery wall with and without permeation. To model LDL nanoparticles, the study randomly injected 100, 500, and 1000 nanoparticles in three release states at each time step, using different geometries. Numerical simulations were performed using COMSOL software, and the results were presented as relative collision of nanoparticles to the walls in tables, diagrams, and shear stress contours. The study found that a graft implantation angle of 15° had the most desirable conditions compared to larger angles, in terms of nanoparticle collision with surfaces and occlusion. The nanoparticle release modes behaved similarly in terms of collision with the surfaces. A difference was observed between CIV and PIV. Saffman lift and wall-induced lift forces having no effect, possibly due to the assumption of a porous artery wall and perpendicular outlet flow. In case of permeable artery walls, relative collision of particles with the graft wall was larger, suggesting the effect of CP of LDLs.
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Affiliation(s)
- Reza Karimian
- Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran
| | - Mohsen Saghafian
- Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran
| | - Ebrahim Shirani
- Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran
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Chen Y, Yang Y, Tan W, Fu L, Deng X, Xing Y. Hemodynamic effects of the human aorta arch with different inflow rate waveforms from the ascending aorta inlet: A numerical study. Biorheology 2021; 58:27-38. [PMID: 33682689 DOI: 10.3233/bir-201009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
BACKGROUND Heart failure (HF) is a common disease globally. Ventricular assist devices (VADs) are widely used to treat HF. In contrast to the natural heart, different VADs generate different blood flow waves in the aorta. OBJECTIVE To explore whether the different inflow rate waveforms from the ascending aorta generate far-reaching hemodynamic influences on the human aortic arch. METHODS An aortic geometric model was reconstructed based on computed tomography data of a patient with HF. A total of five numerical simulations were conducted, including a case with the inflow rate waveforms from the ascending aorta with normal physiological conditions, two HF, and two with typical VAD support. The hemodynamic parameters, wall shear stress (WSS), oscillatory shear index (OSI), relative residence time (RRT), and the strength of the helical flow, were calculated. RESULTS In contrast to the natural heart, numerical simulations showed that HF decreased WSS and induced higher OSI and RRT. Moreover, HF weakened helical flow strength. Pulsatile flow VADs that elevated the WSS, induced some helical flow, while continuous flow VADs could not. CONCLUSIONS HF leads to an adverse hemodynamic environment by decreasing WSS and reducing the helical flow strength. Based upon hemodynamic effects, pulsatile flow VADs may be more advantageous than continuous flow VADs. Thus, pulsatile flow VADs may be a better option for patients with HF.
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Affiliation(s)
- Ying Chen
- College of Engineering and Technology, Beijing Institute of Economics and Management, Beijing, China.,College of Engineering, Peking University, Beijing, China.,Shenzhen Graduate School, Peking University, Shenzhen, China
| | - Yunmei Yang
- Yanshan County People's Hospital of Hebei, Yanshan, Hebei, China
| | - Wenchang Tan
- College of Engineering, Peking University, Beijing, China.,Shenzhen Graduate School, Peking University, Shenzhen, China
| | - Liqin Fu
- College of Engineering and Technology, Beijing Institute of Economics and Management, Beijing, China
| | - Xiaoyan Deng
- Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing, China.,School of Automation and Information Engineering, Sichuan University of Science and Engineering, Zigong, Sichuan, China
| | - Yubin Xing
- Department of Infection Management and Disease Control, The General Hospital of People's Liberation Army, Beijing, China
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Kang H, Yang J, Zhang W, Lu J, Ma X, Sun A, Deng X. Effect of endothelial glycocalyx on water and LDL transport through the rat abdominal aorta. Am J Physiol Heart Circ Physiol 2021; 320:H1724-H1737. [PMID: 33710913 DOI: 10.1152/ajpheart.00861.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Accepted: 03/04/2021] [Indexed: 12/13/2022]
Abstract
The surface of vascular endothelial cells (ECs) is covered by a protective negatively charged layer known as the endothelial glycocalyx. Herein, we hypothesized its transport barrier and mechanosensory role in transmural water flux and low-density lipoprotein (LDL) transport in an isolated rat abdominal aorta perfused under 85 mmHg and 20 dyn/cm2 ex vivo. The endothelial glycocalyx was digested by hyaluronidase (HAase) from bovine tests. Water infiltration velocity (Vw) was measured by a graduated pipette. LDL coverage and mean maximum infiltration distance (MMID) in the vessel wall were quantified by confocal laser scanning microscopy. EC apoptosis was determined by the terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) technique, and leaky junction rates were evaluated by electron microscopy. The results showed that a 42% degradation of the endothelial glycocalyx by HAase treatment increased Vw, LDL coverage, and MMID. Shear stress increased Vw, which cannot be inhibited by HAase treatment. Four hour-shear application increased about fourfolds of LDL coverage, whereas exerted no significant effects on its MMID, EC apoptosis, and the leaky junctions. On the contrary, 24-h shear exposure has no significant effects on LDL coverage, whereas increased 2.74-folds of MMID and about 53% of EC apoptotic rates that could be inhibited by HAase treatment. These results suggest endothelial glycocalyx acts as a transport barrier by decreasing water and LDL transport, as well as a mechanosensor of shear to regulate EC apoptosis, thus affecting leaky junctions and regulating LDL transport into the vessel wall.NEW & NOTEWORTHY A 42% degradation of the endothelial glycocalyx by hyaluronidase of the isolated rat abdominal aorta facilitated water and LDL transport across the vessel wall, suggesting endothelial glycocalyx as a transport barrier. A 24-h shear exposure increased LDL mean maximum infiltration distance, and enhanced EC apoptosis, which could be both inhibited by hyaluronidase treatment, suggesting endothelial glycocalyx may also act as a mechanosensor of shear to regulate EC apoptosis, thus affecting leaky junctions and regulating LDL transport.
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Affiliation(s)
- Hongyan Kang
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
| | - Jiali Yang
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
| | - Weichen Zhang
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
| | - Jinyan Lu
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
| | - Xuejiao Ma
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
| | - Anqiang Sun
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
| | - Xiaoyan Deng
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
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Wang Z, Liu M, Liu X, Sun A, Fan Y, Deng X. Hydraulic conductivity and low-density lipoprotein transport of the venous graft wall in an arterial bypass. Biomed Eng Online 2019; 18:50. [PMID: 31023303 PMCID: PMC6482508 DOI: 10.1186/s12938-019-0669-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 04/12/2019] [Indexed: 11/10/2022] Open
Abstract
Background Blood flow condition may have influence upon the hydraulic conductivity of venous graft (Lp,vein) in an arterial bypass, then affecting the accumulation of low-density lipoproteins (LDLs) within the graft wall. To probe this possibility, we first measured in vitro the filtration rates of swine lateral saphenous vein segments under different flow rates, and the correlation of Lp,vein with wall shear stress (WSS) was then obtained. Results The experimental results showed that when WSS was very low, Lp,vein would increase drastically with WSS from 1.16 ± 0.15 × 10−11 m/s Pa at 0 dyn/cm2 to 2.17 ± 0.20 × 10−11 m/s Pa at 0.7 dyn/cm2, then became constant of approximately 2.33 × 10−11 m/s Pa as the WSS increased further. Based on the experimental results, we assumed three different cases of Lp,vein and numerically simulated the LDLs transport in an arterial bypass model with venous graft. Case A: Lp,vein = 2.33 × 10−11 m/s Pa; Case B: Lp,vein = 1.16 × 10−11 m/s Pa (static condition with WSS of 0); Case C: Lp,vein was shear dependent. The simulation showed that the deposition/accumulation of LDLs within the venous graft wall in Case A was greatly enhanced when compared with that in Case B. However, the LDL accumulation in the graft wall was similar for Case A and Case C. Conclusions Our study, therefore, indicates that when the venous graft was implanted as a bypass graft, the Lp,vein might remain nearly constant along its whole length except for very few areas where the value of WSS was extremely low (less than 0.7 dyn/cm2) and the effects of Lp,vein modulated by blood flow on LDL transport may be neglected.
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Affiliation(s)
- Zhenze Wang
- Beijing Key Laboratory of Rehabilitation Technical Aids for Old-Age Disability, Key Laboratory of Technical Aids Analysis and Identification Key Laboratory of the Ministry of Civil Affairs, National Research Centre for Rehabilitation Technical Aids, Beijing, 100176, China
| | - Ming Liu
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, 100083, China.,Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing, 100083, China
| | - Xiao Liu
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, 100083, China.,Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing, 100083, China
| | - Anqiang Sun
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, 100083, China. .,Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing, 100083, China.
| | - Yubo Fan
- Beijing Key Laboratory of Rehabilitation Technical Aids for Old-Age Disability, Key Laboratory of Technical Aids Analysis and Identification Key Laboratory of the Ministry of Civil Affairs, National Research Centre for Rehabilitation Technical Aids, Beijing, 100176, China. .,Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, 100083, China. .,Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing, 100083, China.
| | - Xiaoyan Deng
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, 100083, China.,Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing, 100083, China
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Zhu Y, Chen R, Juan YH, Li H, Wang J, Yu Z, Liu H. Clinical validation and assessment of aortic hemodynamics using computational fluid dynamics simulations from computed tomography angiography. Biomed Eng Online 2018; 17:53. [PMID: 29720173 PMCID: PMC5932836 DOI: 10.1186/s12938-018-0485-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 04/23/2018] [Indexed: 02/02/2023] Open
Abstract
Background Hemodynamic information including peak systolic pressure (PSP) and peak systolic velocity (PSV) carry an important role in evaluation and diagnosis of congenital heart disease (CHD). Since MDCTA cannot evaluate hemodynamic information directly, the aim of this study is to provide a noninvasive method based on a computational fluid dynamics (CFD) model, derived from multi-detector computed tomography angiography (MDCTA) raw data, to analyze the aortic hemodynamics in infants with CHD, and validate these results against echocardiography and cardiac catheter measurements. Methods This study included 25 patients (17 males, and 8 females; a median age of 2 years, range: 4 months–4 years) with CHD. All patients underwent both transthoracic echocardiography (TTE) and MDCTA within 2 weeks prior to cardiac catheterization. CFD models were created from MDCTA raw data. Boundary conditions were confirmed by lumped parameter model and transthoracic echocardiography (TTE). Peak systolic velocity derived from CFD models (PSVCFD) was compared to TTE measurements (PSVTTE), while the peak systolic pressure derived from CFD (PSPCFD) was compared to catheterization (PSPCC). Regions with low and high peak systolic wall shear stress (PSWSS) were also evaluated. Results PSVCFD and PSPCFD showed good agreements between PSVTTE (r = 0.968, p < 0.001; mean bias = − 7.68 cm/s) and PSPCC (r = 0.918, p < 0.001; mean bias = 1.405 mmHg). Regions with low and high PSWSS) can also be visualized. Skewing of velocity or helical blood flow was also observed at aortic arch in patients. Conclusions Our result demonstrated that CFD scheme based on MDCTA raw data is an accurate and convenient method in obtaining the velocity and pressure from aorta and displaying the distribution of PSWSS and flow pattern of aorta. The preliminary results from our study demonstrate the capability in combining clinical imaging data and novel CFD tools in infants with CHD and provide a noninvasive approach for diagnose of CHD such as coarctation of aorta in future.
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Affiliation(s)
- Yulei Zhu
- Department of Radiology, Guangdong General Hospital, Guangdong Academy of Medical Sciences, No. 106, Zhong Shan Er Lu, Guangzhou, 510080, Guangdong, China.,School of Medicine, South China University of Technology, Guangzhou, 510006, Guangdong, China
| | - Rui Chen
- Department of Radiology, Guangdong General Hospital, Guangdong Academy of Medical Sciences, No. 106, Zhong Shan Er Lu, Guangzhou, 510080, Guangdong, China.,School of Medicine, South China University of Technology, Guangzhou, 510006, Guangdong, China
| | - Yu-Hsiang Juan
- Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital, Linkou Chang Gung University, Taoyuan, Taiwan
| | - He Li
- Department of Cardiac Surgery, Guangdong Cardiovascular Institute, Guangdong Provincial Key Laboratory of South China Structural Heart Disease, Guangdong General Hospital, Guangdong Academy of Medical Sciences, No. 106, Zhong Shan Er Lu, Guangzhou, 510080, Guangdong, China
| | - Jingjing Wang
- Department of Radiology, Guangdong General Hospital, Guangdong Academy of Medical Sciences, No. 106, Zhong Shan Er Lu, Guangzhou, 510080, Guangdong, China.,School of Medicine, South China University of Technology, Guangzhou, 510006, Guangdong, China
| | - Zhuliang Yu
- School of Medicine, South China University of Technology, Guangzhou, 510006, Guangdong, China. .,College of Automation Science and Technology, South China University of Technology, 381 Wushan Road, Guangzhou, 510080, Guangdong, China.
| | - Hui Liu
- Department of Radiology, Guangdong General Hospital, Guangdong Academy of Medical Sciences, No. 106, Zhong Shan Er Lu, Guangzhou, 510080, Guangdong, China. .,School of Medicine, South China University of Technology, Guangzhou, 510006, Guangdong, China.
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Li X, Liu X, Zhang P, Feng C, Sun A, Kang H, Deng X, Fan Y. Numerical simulation of haemodynamics and low-density lipoprotein transport in the rabbit aorta and their correlation with atherosclerotic plaque thickness. J R Soc Interface 2017; 14:rsif.2017.0140. [PMID: 28424305 DOI: 10.1098/rsif.2017.0140] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 03/20/2017] [Indexed: 12/25/2022] Open
Abstract
Two mechanisms of shear stress and mass transport have been recognized to play an important role in the development of localized atherosclerosis. However, their relationship and roles in atherogenesis are still obscure. It is necessary to investigate quantitatively the correlation among low-density lipoproteins (LDL) transport, haemodynamic parameters and plaque thickness. We simulated blood flow and LDL transport in rabbit aorta using computational fluid dynamics and evaluated plaque thickness in the aorta of a high-fat-diet rabbit. The numerical results show that regions with high luminal LDL concentration tend to have severely negative haemodynamic environments (HEs). However, for regions with moderately and slightly high luminal LDL concentration, the relationship between LDL concentration and the above haemodynamic indicators is not clear cut. Point-by-point correlation with experimental results indicates that severe atherosclerotic plaque corresponds to high LDL concentration and seriously negative HEs, less severe atherosclerotic plaque is related to either moderately high LDL concentration or moderately negative HEs, and there is almost no atherosclerotic plaque in regions with both low LDL concentration and positive HEs. In conclusion, LDL distribution is closely linked to blood flow transport, and the synergetic effects of luminal surface LDL concentration and wall shear stress-based haemodynamic indicators may determine plaque thickness.
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Affiliation(s)
- Xiaoyin Li
- Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, People's Republic of China
| | - Xiao Liu
- Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, People's Republic of China
| | - Peng Zhang
- Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, People's Republic of China
| | - Chenglong Feng
- Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, People's Republic of China
| | - Anqiang Sun
- Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, People's Republic of China
| | - Hongyan Kang
- Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, People's Republic of China
| | - Xiaoyan Deng
- Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, People's Republic of China
| | - Yubo Fan
- Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, People's Republic of China .,National Research Center for Rehabilitation Technical Aids, Beijing, People's Republic of China
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The Effect of Fluid Shear Stress on the In Vitro Release Kinetics of Sirolimus from PLGA Films. Polymers (Basel) 2017; 9:polym9110618. [PMID: 30965925 PMCID: PMC6418679 DOI: 10.3390/polym9110618] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 10/31/2017] [Accepted: 11/10/2017] [Indexed: 12/27/2022] Open
Abstract
Drug-carrying coatings of stents implanted in blood vessels are exposed to various blood flows. This study investigated the effect of fluid shear stress on the in vitro release kinetics of sirolimus from poly(lactic-co-glycolic acid) (PLGA) films. The homemade parallel plate flow chamber was used to exert quantitative shear stress on the sirolimus-carrying film. By adjusting the flow rate of the release media in the chamber, three levels of shear stress (3.6, 12.0, and 36.0 dyn/cm²) were respectively applied. For each level of shear stress employed, the release kinetics of sirolimus from the PLGA films exhibited a four-phase profile: an initial burst release phase (Phase I), a lag phase (Phase II), a second burst release phase (Phase III), and a terminal release phase (Phase IV). During Phases I and II, sirolimus was released slowly and in small amounts (<10%); however, during Phases III and IV, the drug release increased considerably. Comparisons of different shear stresses indicated that greater shear stress resulted in earlier and faster sirolimus release, with more cumulative drug release observed. PLGA film degradations (molecular weight reduction, mass loss, and surface topographical variations) were also investigated to better explain the observed drug release behavior. Consequently, fluid shear stress was found to significantly accelerate the release of sirolimus from the PLGA matrices. Therefore, this study could provide a practical method for evaluating the in vitro drug release from polymer matrices under uniform shear stress, and might help improve the design of biodegradable coatings on drug-eluting stents.
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ZHENG QUAN, CHU ZHAOWEI, LI XIAOMING, KANG HONGYAN, YANG XIAO, FAN YUBO. EFFECTS OF AQUEOUS MEDIUM, TWEEN-20 AND FLOW ON THE STABILITY OF SIROLIMUS. J MECH MED BIOL 2017. [DOI: 10.1142/s0219519417500397] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Sirolimus-eluting stents have been widely used in the treatment of coronary artery disease. Prior to the clinical application, the in vitro drug release test is a mandatory requirement for the quality control of sirolimus-eluting stents. How to maintain the stability of sirolimus in the release medium is an important issue throughout the drug release research. In this study, the stability tests of sirolimus in three aqueous media (ultrapure water (UPW), normal saline (NS) and phosphate-buffered saline (PBS, pH 7.4)) were carried out. It was found that the half-lives of sirolimus in UPW, NS and PBS (pH 7.4) were, respectively, 111.8, 43.6 and 11.5[Formula: see text]h. Tween-20 was then added to the above-mentioned three aqueous media and was shown to improve the solubility and stability of sirolimus in aqueous solutions. Under static conditions, the half-life value for sirolimus was significantly increased in the presence of Tween-20 (UPW, 3.5-fold; NS, 2.0-fold; PBS (pH 7.4), 2.7-fold). The effect of solution flow on the stability of sirolimus was also investigated in a flow loop apparatus to mimic vessel-like flow conditions. There was a significant decrease in the stability of sirolimus in aqueous media with the increase of flow rate. The results suggest that aqueous solution supplemented with Tween-20 could be used as the release medium for sirolimus-eluting stents, and that the circulation of the release medium should be controlled at low flow rate.
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Affiliation(s)
- QUAN ZHENG
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, P. R. China
| | - ZHAOWEI CHU
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, P. R. China
| | - XIAOMING LI
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, P. R. China
| | - HONGYAN KANG
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, P. R. China
| | - XIAO YANG
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, P. R. China
| | - YUBO FAN
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, P. R. China
- National Research Center for Rehabilitation Technical Aids, Beijing 100176, P. R. China
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Zhang Q, Gao B, Chang Y. The study on hemodynamic effect of series type LVAD on aortic blood flow pattern: a primary numerical study. Biomed Eng Online 2016; 15:163. [PMID: 28155672 PMCID: PMC5260100 DOI: 10.1186/s12938-016-0252-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Background Left ventricular assist device (LVAD) has become an alternative treatment for end-stage heart failure patients. Series type of LVAD, as a novel LVAD, has attracted more and more attention. The hemodynamic effects of series type LVAD on aortic blood pattern are considered as its important characteristics; however, the precise mechanism of it is still unclear. Methods To clarify the hemodynamic effects of series type LVAD on aortic blood flow pattern, a comparative study on the aortic blood flow pattern and hemodynamic states were carried out numerically for two cases, including series type LVAD support and normal condition. The steady-state computational fluid dynamic (CFD) approach was employed. The blood flow streamline, blood velocity vector and distribution of wall shear stress (WSS) were calculated to evaluate the differences of hemodynamic effects between both conditions. Results The results demonstrated that the aortic flow pattern under series type LVAD showed significant different from that of normal condition. The strength of aortic swirling flow was significantly enhanced by the series type LVAD support. Meanwhile, the rotating direction of swirling flow under LVAD support was also dominated by the rotating direction of series type LVAD. Moreover, the blood velocity and WSS under LVAD support were also significantly enhanced, compared with that under normal condition. Conclusion The hemodynamic states, including the aortic swirling flow characteristic, was significantly dominated by LVAD support. Present investigation could provide not only a useful information on the vascular complications caused by LVAD support, but also provide a useful guide for optimal the structure of the series type LVAD.
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Affiliation(s)
- Qi Zhang
- School of Life Science and BioEngineering, Beijing University of Technology, Beijing, 100124, People's Republic of China
| | - Bin Gao
- School of Life Science and BioEngineering, Beijing University of Technology, Beijing, 100124, People's Republic of China
| | - Yu Chang
- School of Life Science and BioEngineering, Beijing University of Technology, Beijing, 100124, People's Republic of China.
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