Subjects -> MEDICAL SCIENCES (Total: 8669 journals)
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CARDIOVASCULAR DISEASES (338 journals)                  1 2 | Last

Showing 1 - 200 of 338 Journals sorted alphabetically
Acta Angiologica     Open Access   (Followers: 5)
Acta Cardiologica     Hybrid Journal   (Followers: 2)
Acute Cardiac Care     Hybrid Journal   (Followers: 8)
Adipositas - Ursachen, Folgeerkrankungen, Therapie     Hybrid Journal  
AJP Heart and Circulatory Physiology     Hybrid Journal   (Followers: 12)
Aktuelle Kardiologie     Hybrid Journal   (Followers: 1)
American Heart Journal     Hybrid Journal   (Followers: 60)
American Journal of Cardiology     Hybrid Journal   (Followers: 68)
American Journal of Cardiovascular Drugs     Hybrid Journal   (Followers: 18)
American Journal of Hypertension     Hybrid Journal   (Followers: 29)
Anales de Cirugia Vascular     Full-text available via subscription   (Followers: 1)
Anatolian Journal of Cardiology     Open Access   (Followers: 6)
Angiología     Full-text available via subscription  
Angiologia e Cirurgia Vascular     Open Access   (Followers: 1)
Angiology     Hybrid Journal   (Followers: 3)
Annales de Cardiologie et d'Angéiologie     Full-text available via subscription   (Followers: 1)
Annals of Circulation     Open Access   (Followers: 2)
Annals of Noninvasive Electrocardiology     Hybrid Journal   (Followers: 1)
Annals of Pediatric Cardiology     Open Access   (Followers: 12)
AORTA     Open Access  
Archives of Cardiovascular Diseases     Full-text available via subscription   (Followers: 6)
Archives of Cardiovascular Diseases Supplements     Full-text available via subscription   (Followers: 4)
Archives of Cardiovascular Imaging     Open Access   (Followers: 2)
Archivos de cardiología de México     Open Access   (Followers: 1)
Argentine Journal of Cardiology (English edition)     Open Access   (Followers: 2)
Arquivos Brasileiros de Cardiologia     Open Access   (Followers: 2)
Arrhythmia & Electrophysiology Review     Open Access   (Followers: 1)
Arteriosclerosis, Thrombosis and Vascular Biology     Full-text available via subscription   (Followers: 33)
Artery Research     Hybrid Journal   (Followers: 5)
ARYA Atherosclerosis     Open Access  
ASAIO Journal     Hybrid Journal   (Followers: 4)
ASEAN Heart Journal     Open Access   (Followers: 3)
Asian Cardiovascular and Thoracic Annals     Hybrid Journal   (Followers: 2)
Aswan Heart Centre Science & Practice Services     Open Access   (Followers: 1)
Atherosclerosis : X     Open Access  
Bangladesh Heart Journal     Open Access   (Followers: 3)
Basic Research in Cardiology     Hybrid Journal   (Followers: 9)
BMC Cardiovascular Disorders     Open Access   (Followers: 22)
Brain Circulation     Open Access   (Followers: 1)
British Journal of Cardiology     Full-text available via subscription   (Followers: 18)
Canadian Journal of Cardiology     Hybrid Journal   (Followers: 18)
Cardiac Cath Lab Director     Full-text available via subscription  
Cardiac Electrophysiology Review     Hybrid Journal   (Followers: 2)
Cardiac Failure Review     Open Access   (Followers: 2)
Cardiocore     Full-text available via subscription   (Followers: 1)
Cardiogenetics     Open Access   (Followers: 3)
Cardiology     Full-text available via subscription   (Followers: 20)
Cardiology and Angiology: An International Journal     Open Access   (Followers: 1)
Cardiology and Therapy     Open Access   (Followers: 11)
Cardiology Clinics     Full-text available via subscription   (Followers: 14)
Cardiology in Review     Hybrid Journal   (Followers: 9)
Cardiology in the Young     Hybrid Journal   (Followers: 35)
Cardiology Journal     Open Access   (Followers: 6)
Cardiology Plus     Open Access   (Followers: 1)
Cardiology Research     Open Access   (Followers: 15)
Cardiology Research and Practice     Open Access   (Followers: 11)
Cardiopulmonary Physical Therapy Journal     Hybrid Journal   (Followers: 9)
Cardiorenal Medicine     Full-text available via subscription   (Followers: 1)
Cardiothoracic Surgeon     Open Access   (Followers: 1)
CardioVasc     Full-text available via subscription   (Followers: 1)
Cardiovascular & Haematological Disorders - Drug Targets     Hybrid Journal   (Followers: 1)
Cardiovascular & Hematological Agents in Medicinal Chemistry     Hybrid Journal   (Followers: 2)
CardioVascular and Interventional Radiology     Hybrid Journal   (Followers: 15)
Cardiovascular and Thoracic Open     Open Access  
Cardiovascular Diabetology     Open Access   (Followers: 10)
Cardiovascular Drugs and Therapy     Hybrid Journal   (Followers: 14)
Cardiovascular Endocrinology & Metabolism     Hybrid Journal   (Followers: 1)
Cardiovascular Engineering     Hybrid Journal   (Followers: 1)
Cardiovascular Engineering and Technology     Hybrid Journal   (Followers: 1)
Cardiovascular Intervention and Therapeutics     Hybrid Journal   (Followers: 5)
Cardiovascular Journal     Open Access   (Followers: 6)
Cardiovascular Journal of Africa     Full-text available via subscription   (Followers: 5)
Cardiovascular Journal of South Africa     Full-text available via subscription   (Followers: 2)
Cardiovascular Medicine in General Practice     Full-text available via subscription   (Followers: 7)
Cardiovascular Pathology     Hybrid Journal   (Followers: 4)
Cardiovascular Regenerative Medicine     Open Access  
Cardiovascular Research     Hybrid Journal   (Followers: 16)
Cardiovascular Revascularization Medicine     Hybrid Journal   (Followers: 1)
Cardiovascular System     Open Access  
Cardiovascular Therapeutics     Open Access   (Followers: 1)
Cardiovascular Toxicology     Hybrid Journal   (Followers: 6)
Cardiovascular Ultrasound     Open Access   (Followers: 5)
Case Reports in Cardiology     Open Access   (Followers: 7)
Catheterization and Cardiovascular Interventions     Hybrid Journal   (Followers: 3)
Cerebrovascular Diseases     Full-text available via subscription   (Followers: 3)
Cerebrovascular Diseases Extra     Open Access  
Chest     Full-text available via subscription   (Followers: 103)
Choroby Serca i Naczyń     Open Access   (Followers: 1)
Circulation     Hybrid Journal   (Followers: 267)
Circulation : Cardiovascular Imaging     Hybrid Journal   (Followers: 15)
Circulation : Cardiovascular Interventions     Hybrid Journal   (Followers: 19)
Circulation : Cardiovascular Quality and Outcomes     Hybrid Journal   (Followers: 11)
Circulation : Genomic and Precision Medicine     Hybrid Journal   (Followers: 16)
Circulation : Heart Failure     Hybrid Journal   (Followers: 26)
Circulation Research     Hybrid Journal   (Followers: 35)
Cirugía Cardiovascular     Open Access  
Clínica e Investigación en Arteriosclerosis     Full-text available via subscription  
Clínica e Investigación en arteriosclerosis (English Edition)     Hybrid Journal  
Clinical and Experimental Hypertension     Hybrid Journal   (Followers: 3)
Clinical Cardiology     Hybrid Journal   (Followers: 10)
Clinical Hypertension     Open Access   (Followers: 5)
Clinical Medicine Insights : Cardiology     Open Access   (Followers: 6)
Clinical Research in Cardiology     Hybrid Journal   (Followers: 5)
Clinical Research in Cardiology Supplements     Hybrid Journal  
Clinical Trials and Regulatory Science in Cardiology     Open Access   (Followers: 4)
Congenital Heart Disease     Hybrid Journal   (Followers: 6)
Congestive Heart Failure     Hybrid Journal   (Followers: 4)
Cor et Vasa     Full-text available via subscription   (Followers: 1)
Coronary Artery Disease     Hybrid Journal   (Followers: 3)
CorSalud     Open Access  
Critical Pathways in Cardiology     Hybrid Journal   (Followers: 5)
Current Cardiology Reports     Hybrid Journal   (Followers: 6)
Current Cardiology Reviews     Hybrid Journal   (Followers: 3)
Current Cardiovascular Imaging Reports     Hybrid Journal   (Followers: 1)
Current Cardiovascular Risk Reports     Hybrid Journal  
Current Heart Failure Reports     Hybrid Journal   (Followers: 5)
Current Hypertension Reports     Hybrid Journal   (Followers: 6)
Current Hypertension Reviews     Hybrid Journal   (Followers: 6)
Current Opinion in Cardiology     Hybrid Journal   (Followers: 13)
Current Problems in Cardiology     Hybrid Journal   (Followers: 3)
Current Research : Cardiology     Full-text available via subscription   (Followers: 1)
Current Treatment Options in Cardiovascular Medicine     Hybrid Journal   (Followers: 1)
Current Vascular Pharmacology     Hybrid Journal   (Followers: 5)
CVIR Endovascular     Open Access   (Followers: 1)
Der Kardiologe     Hybrid Journal   (Followers: 1)
Echo Research and Practice     Open Access   (Followers: 2)
Echocardiography     Hybrid Journal   (Followers: 4)
Egyptian Heart Journal     Open Access   (Followers: 2)
Egyptian Journal of Cardiothoracic Anesthesia     Open Access  
ESC Heart Failure     Open Access   (Followers: 4)
European Cardiology Review     Open Access   (Followers: 1)
European Heart Journal     Hybrid Journal   (Followers: 67)
European Heart Journal - Cardiovascular Imaging     Hybrid Journal   (Followers: 10)
European Heart Journal - Cardiovascular Pharmacotherapy     Full-text available via subscription   (Followers: 2)
European Heart Journal - Quality of Care and Clinical Outcomes     Hybrid Journal  
European Heart Journal : Acute Cardiovascular Care     Hybrid Journal   (Followers: 1)
European Heart Journal : Case Reports     Open Access   (Followers: 1)
European Heart Journal Supplements     Hybrid Journal   (Followers: 7)
European Journal of Cardio-Thoracic Surgery     Hybrid Journal   (Followers: 9)
European Journal of Cardio-Thoracic Surgery Supplements     Full-text available via subscription   (Followers: 2)
European Journal of Cardiovascular Nursing     Hybrid Journal   (Followers: 5)
European Journal of Heart Failure     Hybrid Journal   (Followers: 13)
European Journal of Preventive Cardiology.     Hybrid Journal   (Followers: 6)
European Stroke Organisation     Hybrid Journal   (Followers: 3)
Experimental & Translational Stroke Medicine     Open Access   (Followers: 9)
Expert Review of Cardiovascular Therapy     Full-text available via subscription   (Followers: 3)
Folia Cardiologica     Open Access  
Forum Zaburzeń Metabolicznych     Hybrid Journal  
Frontiers in Cardiovascular Medicine     Open Access   (Followers: 1)
Future Cardiology     Hybrid Journal   (Followers: 5)
General Thoracic and Cardiovascular Surgery     Hybrid Journal   (Followers: 3)
Global Cardiology Science and Practice     Open Access   (Followers: 5)
Global Heart     Hybrid Journal   (Followers: 3)
Heart     Hybrid Journal   (Followers: 48)
Heart and Mind     Open Access  
Heart and Vessels     Hybrid Journal  
Heart Failure Clinics     Full-text available via subscription   (Followers: 2)
Heart Failure Reviews     Hybrid Journal   (Followers: 3)
Heart India     Open Access   (Followers: 2)
Heart International     Full-text available via subscription  
Heart Rhythm     Hybrid Journal   (Followers: 11)
Heart Views     Open Access   (Followers: 2)
HeartRhythm Case Reports     Open Access  
Hellenic Journal of Cardiology     Open Access   (Followers: 1)
Herz     Hybrid Journal   (Followers: 2)
High Blood Pressure & Cardiovascular Prevention     Full-text available via subscription   (Followers: 2)
Hypertension     Full-text available via subscription   (Followers: 23)
Hypertension     Open Access   (Followers: 2)
Hypertension in Pregnancy     Hybrid Journal   (Followers: 9)
Hypertension Research     Hybrid Journal   (Followers: 4)
Ibrahim Cardiac Medical Journal     Open Access  
IJC Heart & Vessels     Open Access   (Followers: 1)
IJC Heart & Vasculature     Open Access   (Followers: 1)
IJC Metabolic & Endocrine     Open Access   (Followers: 1)
Indian Heart Journal     Open Access   (Followers: 5)
Indian Journal of Cardiovascular Disease in Women WINCARS     Open Access  
Indian Journal of Thoracic and Cardiovascular Surgery     Hybrid Journal  
Indian Pacing and Electrophysiology Journal     Open Access   (Followers: 1)
Innovations : Technology and Techniques in Cardiothoracic and Vascular Surgery     Hybrid Journal   (Followers: 1)
Insuficiencia Cardíaca     Open Access  
Interactive CardioVascular and Thoracic Surgery     Hybrid Journal   (Followers: 7)
International Cardiovascular Forum Journal     Open Access  
International Journal of Angiology     Hybrid Journal   (Followers: 2)
International Journal of Cardiology     Hybrid Journal   (Followers: 17)
International Journal of Cardiology Hypertension     Open Access   (Followers: 1)
International Journal of Cardiovascular and Cerebrovascular Disease     Open Access   (Followers: 3)
International Journal of Cardiovascular Imaging     Hybrid Journal   (Followers: 2)
International Journal of Cardiovascular Research     Hybrid Journal   (Followers: 6)
International Journal of Heart Rhythm     Open Access  
International Journal of Hypertension     Open Access   (Followers: 8)
International Journal of Hyperthermia     Open Access  
International Journal of Stroke     Hybrid Journal   (Followers: 32)
International Journal of the Cardiovascular Academy     Open Access  
Interventional Cardiology Clinics     Full-text available via subscription   (Followers: 2)
Interventional Cardiology Review     Open Access  
JACC : Basic to Translational Science     Open Access   (Followers: 5)
JACC : Cardiovascular Imaging     Hybrid Journal   (Followers: 18)
JACC : Cardiovascular Interventions     Hybrid Journal   (Followers: 19)
JACC : Heart Failure     Full-text available via subscription   (Followers: 14)
JAMA Cardiology     Hybrid Journal   (Followers: 30)

        1 2 | Last

Similar Journals
Journal Cover
Cardiovascular Engineering and Technology
Journal Prestige (SJR): 0.448
Citation Impact (citeScore): 1
Number of Followers: 1  
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1869-408X - ISSN (Online) 1869-4098
Published by Springer-Verlag Homepage  [2626 journals]
  • The Length Versus Diameter Relationship and Radial Force Properties of the
           Amplatzer™ Vascular Plug Type IV: Observations for Oversizing
    • Abstract: Background In palliated single ventricle patients aortopulmonary collateralization is a cause for significant loss of cardiovascular efficiency. In larger vessels, device occlusion becomes an alternative to embolization with multiple coils. The physical characteristics of the Amplatzer ™ Vascular Plug Type IV (AVPIV) are potentially conducive to oversizing the device allowing coverage of a longer portion of vessel. Despite the widespread use of the AVPIV, little published data exists describing the behavior of the device as it is constrained in different vessel sizes. Methods 4–8 mm AVPIV devices were measured in glass tubing in diameters ranging from 1 to 8 mm internal diameter. Radial force was measured by constraining the devices to the desire diameters from 1 to 7 mm and measuring the force the device exerted to one of the constraining walls. This force vs. diameter relationship was evaluated for each device and compared across different devices. Results The devices range in length from 12.36 to 31.24 mm. The 4 mm device lengthened 3.44 mm from unconstrained to 1 mm diameter (12.36 to 15.80 mm), while the 8 mm AVP IV lengthened 14.74 mm from unconstrained to 1 mm diameter constraint (16.50–31.24 mm, 89% lengthening). The highest overall radial force (1.38 N), radial force at 50% compression (1.25 N), and average stiffness (0.95 N/mm) was found in the 5 mm diameter device. Conclusions The AVP IV device has a reliable length for diameter relationship. A counterintuitive property of the AVP IV with regards to radial force for device size was found. The 5 mm AVPIV was found to exert the highest radial force and stiffness compared to the other devices. The 7 and 8 mm AVPIV devices were consistently found to exert less radial force. This property suggests that oversizing an AVP IV could be safe and effective, potentially decreasing total devices used, cost, and overall procedure time.
      PubDate: 2019-03-21
  • Assessing the Thrombogenic Potential of Heart Valve Prostheses: An
           Approach for a Standardized In - Vitro Method
    • Abstract: Purpose Thrombogenic complications are still a main issue in the general performance of cardiovascular implants, especially heart valves. To date, the thrombogenic potential of those prostheses is pre-clinically assessed in time consuming animal studies with questionable evidence. Methods In this study, we present a new in-vitro method to assess and compare deficiencies of heart valve substitutes concerning their thrombogenic performance and locate initial clot formation under physiological conditions using porcine blood. Therefore, an athrombogenic pulse duplicator (THIA3) was developed that simulates the anatomic and hemodynamic conditions in the vicinity of the aortic valve. Validation of this tester was carried out with regard to hemodynamics, reproducibility and using positive and negative control valves and by comparison of clot locations with literature data from chronic animal trials with sheep using a St. Jude bileaflet valve. Results Validation of the tester showed quasi-physiological hemodynamics and reproducible clot formation. Identical clot formations were found comparing findings in vitro with chronic animal trials. Conclusion The THIA 3 has proven its suitability for valid, reproducible evaluation of thrombogenic potential of heart valves in a short period of time.
      PubDate: 2019-03-06
  • A New Method for Simulating Embolic Coils as Heterogeneous Porous Media
    • Abstract: Purpose To gain insight into the influence of coils on aneurysmal hemodynamics, computational fluid dynamics (CFD) can be used. Conventional methods of modeling coils consider the explicit geometry of the deployed devices within the aneurysm and discretize the fluid domain. However, the complex geometry of a coil mass leads to cumbersome domain discretization along with a significant number of mesh elements. These problems have motivated a homogeneous porous medium coil model, whereby the explicit geometry of the coils is greatly simplified, and relevant homogeneous porous medium parameters are approximated. Unfortunately, since the coils are not distributed uniformly in the aneurysm, the homogeneity assumption is no longer valid. Methods In this paper, a novel heterogeneous porous medium approach is introduced. To verify the model, we performed CFD simulations to calculate the pressure drop caused by actual deployed coils in a straight cylinder. Next, we considered three different anatomical aneurysm geometries virtually treated with coils and studied the hemodynamics using the presented heterogeneous porous medium model. Results We show that the blood kinetic energy predicted by the heterogeneous model is in strong agreement with the conventional approach. The homogeneity assumption, on the other hand, significantly over-predicts the blood kinetic energy within the aneurysmal sac. Conclusions These results indicate that the benefits of the porous medium assumption can be retained if a heterogeneous approach is applied. Implementation of the presented method led to a substantial reduction in the total number of mesh elements compared to the conventional method, and greater accuracy was enabled by considering heterogeneity compared to the homogenous approach.
      PubDate: 2019-03-01
  • A Computational Study of Mechanical Performance of Bioresorbable Polymeric
           Stents with Design Variations
    • Abstract: Purpose The study compared the mechanical behavior of bioresorbable polymeric stents with various designs during deployment, and investigated their fatigue performance under pulsatile blood pressure loading. Methods Finite element simulations have been carried out to compare the mechanical performance of four bioresorbable polymeric stents, i.e., Absorb, Elixir, Igaki-Tamai and RevaMedical, during deployment in diseased artery. Tri-folded balloon was modelled to expand the crimped stent onto the three-layered arterial wall with plaque. Cyclic diastolic-systolic pressure loading was applied to both stent and arterial wall to study fatigue behavior. Results Stents with larger U-bend and longer axial strut demonstrate more flexibility but suffer from severe dogboning and recoiling effects. Stress concentrations in the stent, as well as in the plaque and artery, are higher for stents designed with increased rigidity such as those with smaller U-bends and shorter axial struts. Simulations of fatigue deformation for Elixir stent demonstrate that the U-bends, with high stress concentrations, have a potential risk of fatigue failure under pulsatile systolic-diastolic blood pressure as opposed to the counter metallic stents which are normally free of fatigue failure. Conclusion The structural behaviour of bioresorbable polymeric stent is strongly affected by its design, in terms of expansion, dogboning, recoiling and stress distribution during the deployment process.
      PubDate: 2019-03-01
  • Mechanical Characterization of the Lamellar Structure of Human Abdominal
           Aorta in the Development of Atherosclerosis: An Atomic Force Microscopy
    • Abstract: Abstract Atherosclerosis is a major risk factor for cardiovascular disease. However, mechanisms of interaction of atherosclerotic plaque development and local stiffness of the lamellar structure of the arterial wall are not well established. In the current study, the local Young’s modulus of the wall and plaque components were determined for three different groups of healthy, mildly diseased and advanced atherosclerotic human abdominal aortas. Histological staining was performed to highlight the atherosclerotic plaque components and lamellar structure of the aortic media, consisting of concentric layers of elastin and interlamellar zones. The force spectroscopy mode of the atomic force microscopy was utilized to determine Young’s moduli of aortic wall lamellae and plaque components at the micron level. The high variability of Young’s moduli (E) at different locations of the atherosclerotic plaque such as the fibrous cap (E = 15.5± 2.6 kPa), calcification zone (E = 103.7±19.5 kPa), and lipid pool (E = 3.5±1.2 kPa) were observed. Reduction of elastin lamellae stiffness (18.6%), as well as stiffening of interlamellar zones (50%), were detected in the diseased portion of the medial layer of abdominal aortic wall compared to the healthy artery. Additionally, significant differences in the stiffness of both elastin lamellae and interlamellar zones were observed between the diseased wall and disease-free wall in incomplete plaques. Our results elucidate the alternation of the stiffness of different lamellae in the human abdominal aortic wall with atherosclerotic plaque development and may provide new insight on the remodeling of the aortic wall during the progression of atherosclerosis.
      PubDate: 2019-03-01
  • Objective Uniaxial Identification of Transition Points in Non-Linear
           Materials: Sample Application to Porcine Coronary Arteries and the
           Dependency of Their Pre- and Post-Transitional Moduli with Position
    • Abstract: Purpose This study aimed to develop an objective method for the elastic characterisation of pre- and post-transitional moduli of left anterior descending (LAD) porcine coronary arteries. Methods Eight coronary arteries were divided into proximal, middle and distal test specimens. Specimens underwent uniaxial extension up to 3 mm. Force–displacement measurements were used to determine the induced true stress and stretch for each specimen. A local maximum of the stretch-true stress data was used to identify a transition point. Pre- and post-transitional moduli were calculated up to and from this point, respectively. Results The mean pre-transitional moduli for all specimens was 0.76 MPa, as compared to 4.86 MPa for the post-transitional moduli. However, proximal post-transitional moduli were significantly greater than that of middle and distal test specimens (p < 0.05). Conclusion Post-transitional uniaxial properties of the LAD are dependent on location along the artery. Further, it is feasible to objectively identify a transition point between pre- and post-transitional moduli.
      PubDate: 2019-03-01
  • Effect of Varying Viscosity on Two-Fluid Model of Blood Flow through
           Constricted Blood Vessels: A Comparative Study
    • Abstract: Purpose Most of the previously studied non-Newtonian blood flow models considered blood viscosity to be constant but for correct measurement of flow rate and flow resistance, the hematocrit dependent viscosity will be better as various literature suggested the variable nature of blood viscosity. Present work concerns the steady and pulsatile nature of blood flow through constricted blood vessels. Two-fluid model for blood is considered with the suspension of all the RBCs (erythrocytes) in the core region as a non-Newtonian (Herschel–Bulkley) fluid and the plasma in the cell free region near wall as a Newtonian fluid. No slip condition on the wall and radially varying viscosity has been taken. Methods For steady flow the analytical approach has been taken to obtain the exact solution. Regular perturbation expansion method has been used to solve the governing equations for pulsatile flow up to first order of approximation by assuming the pulsatile Reynolds number to be very small (much less than unity). Results Flow rate, wall shear stress and velocity profile have been graphically analyzed and compared with constant viscosity model. A noteworthy observation of the present study is that rise in viscosity index leads to decay in velocity, velocity of plug flow region, flow rate while flow resistance increases with rising viscosity index (m). The results for Power-law fluid (PL), Bingham-plastic fluid (BP), Newtonian fluid (NF) are found as special cases from this model. Like the constant viscosity model, it has been also observed that the velocity, flow rate and plug core velocity of two-fluid model are higher than the single-fluid model for variable viscosity. Conclusions The two-phase fluid model is more significant than the single-fluid model. Effect of viscosity parameter on various hemodynamical quantities has been obtained. It is also concluded that a rising viscosity parameter (varying nature of viscosity) significantly distinguishes the single and two-fluid models in terms of changes in blood flow resistance. The outcome of present study may leave a significant impact on analyzing blood flow through small blood vessels with constriction, where correct measurement of flow rate and flow resistance for medical treatment is very important.
      PubDate: 2019-03-01
  • Reversed Auxiliary Flow to Reduce Embolism Risk During TAVI: A
           Computational Simulation and Experimental Study
    • Abstract: Introduction Endovascular treatments, such as transcatheter aortic valve implantation (TAVI), carry a risk of embolization due to debris dislodgement during various procedural steps. Although embolic filters are already available and marketed, mechanisms underlying cerebral embolism still need to be elucidated in order to further reduce cerebrovascular events. Methods We propose an experimental framework with an in silico duplicate allowing release of particles at the level of the aortic valve and their subsequent capture in the supra-aortic branches, simulating embolization under constant inflow and controlled hemodynamic conditions. The effect of a simple flow modulation, consisting of an auxiliary constant flow via the right subclavian artery (RSA), on the amount of particle entering the brachiocephalic trunk was investigated. Preliminary computational fluid dynamics (CFD) simulations were performed in order to assess the minimum retrograde flow-rate from RSA required to deviate particles. Results Our results show that a constant reversed auxiliary flow of 0.5 L/min from the RSA under a constant inflow of 4 L/min from the ascending aorta is able to protect the brachiocephalic trunk from particle embolisms. Both computational and experimental results also demonstrate that the distribution of the bulk flow dictates the distribution of the particles along the aortic branches. This effect has also shown to be independent of release location and flow rate. Conclusions The present study confirms that the integration of in vitro experiments and in silico analyses allows designing and benchmarking novel solutions for cerebral embolic protection during TAVI such as the proposed embo-deviation technique based on an auxiliary retrograde flow from the right subclavian artery.
      PubDate: 2019-03-01
  • A Valveless Pulsatile Pump for the Treatment of Heart Failure with
           Preserved Ejection Fraction: A Simulation Study
    • Abstract: Purpose Effective treatment of patients with terminal heart failure and preserved ejection fraction (HFpEF) is an unmet medical need. The aim of this study was to investigate a novel valveless pulsatile pump as a therapeutic option for the HFpEF population through comprehensive in silico investigations. Methods The pump was simulated in a numerical model of the cardiovascular system of four HFpEF phenotypes and compared to a typical case of heart failure with reduced ejection fraction (HFrEF). The proposed pump, which was modeled as being directly connected to the left ventricle, features a single valveless inlet and outlet cannula and is driven in co-pulsation with the left ventricle. We collected hemodynamics for two different pump volumes (30 and 60 mL). Results In all HFpEF conditions, the 30 mL pump improved the cardiac output by approximately 1 L/min, increased the mean arterial pressure by > 11% and lowered the mean left atrial pressure by > 30%. With the larger (60 mL) stroke volume, these hemodynamic improvements were more pronounced. In the HFrEF condition however, these effects were three times less in magnitude. Conclusions In this simulation study, the valveless pulsatile device improves hemodynamics in HFpEF patients by increasing the total stroke volume. The hemodynamic benefits are achieved with a small device volume comparable to implantable rotary blood pumps.
      PubDate: 2019-03-01
  • Patient-Specific Multi-Scale Model Analysis of Hemodynamics Following the
           Hybrid Norwood Procedure for Hypoplastic Left Heart Syndrome: Effects of
           Reverse Blalock–Taussig Shunt Diameter
    • Abstract: Introduction The hybrid Norwood (HN) is a relatively new first stage palliative procedure for neonates with hypoplastic left heart syndrome, in which a sustainable uni-ventricular circulation is established in a less invasive manner than with the standard Norwood procedure. A computational multiscale model of the circulation following the HN procedure was used to obtain detailed hemodynamics. Implementation of a reverse-BT shunt (RBTS), a synthetic bypass from the main pulmonary to the innominate artery placed to counteract aortic arch stenosis, and its effects on local and global hemodynamics were studied. Methods A post-op patient-derived anatomy of the HN procedure was utilized with varying degrees of distal arch obstruction, or stenosis, (nominal and 90% lumenal area reduction) and varying RBTS diameters (3.0, 3.5, 4.0 mm). A closed lumped parameter model (LPM) for the proximal and peripheral circulations was coupled to a 3D computational fluid dynamics (CFD) model in order to obtain converged flow fields for analysis. Results CFD analyses of patient-derived anatomic configurations demonstrated consistent trends of vascular bed perfusion, vorticity, oscillatory shear index and wall shear stress levels. In the models with severe stenosis, implementation of the RBTS resulted in a restoration of arterial perfusion to near-nominal levels regardless of the shunt diameter. Shunt flow velocity, vorticity, and overall wall shear stress levels decreased with increasing shunt diameter, while shunt flow and systemic oxygen delivery increased with increased shunt diameter. In the absence of distal arch stenosis, large (4.0 mm) grafts may risk thrombosis due to low velocities and flow patterns. Conclusion Among the three graft sizes, the best option seems to be the 3.5 mm RBTS which provides a more organized flow similar to that of the 3.0 mm configuration with lower levels of wall shear stress. As such, in the setting of this study and for comparable HN physiologies our results suggest that: (1) the 4.0 mm shunt is a generous shunt diameter choice that may be problematic particularly when implemented prophylactically in the absence of stenosis, and (2) the 3.5 mm shunt may be a more suitable alternative since it exhibits more favorable hemodynamics at lower levels of wall shear stress.
      PubDate: 2019-03-01
  • Multi-Objective Optimization Design of Balloon-Expandable Coronary Stent
    • Abstract: Purpose Recent studies suggested that suboptimal delivery and longitudinal stent deformation can result in in-stent restenosis. Therefore, the purpose of this paper was to study the effect of stent geometry on stent flexibility and longitudinal stiffness (LS) and optimize the two metrics simultaneously. Then, the reliable and accurate relationships between metrics and design variables were established. Methods A multi-objective optimization method based on finite element analysis was proposed for the investigation and improvement of stent flexibility and LS. The relative influences of design variables on the two metrics were evaluated on the basis of the main effects. Three surrogate models, namely, the response surface model (RSM), radial basis function neural network (RBF), and Kriging were employed and compared. Results The accuracies of the three models in fitting flexibility were nearly similar, although Kriging made more accurate prediction in LS. The link width played important roles in flexibility and LS. Although the flexibility of the optimal stent decreased by 13%, the LS increased by 48.3%. Conclusions The obtained results showed that the multi-objective optimization method is efficient in predicting an optimal stent design. The method presented in this paper can be useful in optimizing stent design and improving the comprehensive mechanical properties of stents.
      PubDate: 2019-03-01
  • Quantitative Characterization of Aortic Valve Endothelial Cell Viability
           and Morphology In Situ Under Cyclic Stretch
    • Abstract: Abstract Current protocols for mechanical preconditioning of tissue engineered heart valves have focused on application of pressure, flexure and fluid flow to stimulate collagen production, ECM remodeling and improving mechanical performance. The aim of this study was to determine if mechanical preconditioning with cyclic stretch could promote an intact endothelium that resembled the viability and morphology of a native valve. Confocal laser scanning microscopy was used to image endothelial cells on aortic valve strips subjected to static incubation or physiological strain regimens. An automated image analysis program was designed and implemented to detect and analyze live and dead cells in images captured of a live aortic valve endothelium. The images were preprocessed, segmented, and quantitatively analyzed for live/dead cell ratio, minimum neighbor distance and circularity. Significant differences in live/dead cellular ratio and the minimum distance between cells were observed between static and strained endothelia, indicating that cyclic strain is an important stimulus for maintaining a healthy endothelium. In conclusion, in vitro application of physiological levels of cyclic strain to tissue engineered heart valves seeded with autologous endothelial cells would be advantageous.
      PubDate: 2019-03-01
  • Estimation of Biomechanical Properties of Normal and Atherosclerotic
           Common Carotid Arteries
    • Abstract: Purpose We developed a modified Kelvin model so that the periodic changes of the arterial intima–media thickness (IMT) over the cardiac cycle were involved. Modified model was implemented for carotid artery, solved via a parameter optimization technique and biomechanical parameters of the model. Methods Consecutive ultrasonic images of the common carotid artery of 30 male patients including 10 healthy subjects, 10 subjects with mild and 10 subjects with sever stenosis were recorded and processed offline. Temporal changes of the internal diameter and IMT were extracted using a combined maximum gradient and dynamic programming algorithm. The blood pressure waveforms were deduced calibrating the internal diameter waveforms using an empirical exponential relationship. Results According to the results of the ANOVA statistical analysis, mean values of the zero pressure radiuses, stress relaxation times, elastic moduli and strain relaxation times of the common carotid arteries of three groups were significantly different. Mentioned parameters increased 11, 24, 7 and 6% in patients with mild (< 50%) stenosis and 12, 73, 8 and 61% in the group with sever stenosis (> 50%) relative to healthy group. Conclusion Present study can be an indicative of the general state of the vascular system and be used for discriminating atherosclerotic from healthy arteries.
      PubDate: 2019-03-01
  • Cardiac Valve Bioreactor for Physiological Conditioning and Hydrodynamic
           Performance Assessment
    • Abstract: Purpose Tissue engineered heart valves (TEHV) are being investigated to address the limitations of currently available valve prostheses. In order to advance a wide variety of TEHV approaches, the goal of this study was to develop a cardiac valve bioreactor system capable of conditioning living valves with a range of hydrodynamic conditions as well as capable of assessing hydrodynamic performance to ISO 5840 standards. Methods A bioreactor system was designed based on the Windkessel approach. Novel features including a purpose-built valve chamber and pressure feedback control were incorporated to maintain asepsis while achieving a range of hydrodynamic conditions. The system was validated by testing hydrodynamic conditions with a bioprosthesis and by operating with cell culture medium for 4 weeks and living cells for 2 weeks. Results The bioreactor system was able to produce a range of pressure and flow conditions from static to resting adult left ventricular outflow tract to pathological including hypertension. The system operated aseptically for 4 weeks and cell viability was maintained for 2 weeks. The system was also able to record the pressure and flow data needed to calculate effective orifice area and regurgitant fraction. Conclusions We have developed a single bioreactor system that allows for step-wise conditioning protocols to be developed for each unique TEHV design as well as allows for hydrodynamic performance assessment.
      PubDate: 2019-03-01
  • A Novel Pulse Damper for Endothelial Cell Flow Bioreactors
    • Abstract: Purpose Peristaltic pumps (PP) are favored in flow bioreactors for their non-contact sterile design. But they produce pulsatile flow, which is consequential for the cultured cells. A novel pulse damper (PD) is reported for pulsatility elimination. Methods The PD design was implemented to target static pressure pulsatility and flow rate (velocity) pulsatility from a PP. Damping effectiveness was tested in a macro-scale, closed-loop recirculating bioreactor mimicking the aortic arch at flow rates up to (4 L/min). Time-resolved particle image velocimetry was used to characterize the velocity field. Endothelial cells (EC) were grown in the bioreactor, and subjected to continuous flow for 15 min with or without PD. Results The PD was found to be nearly 90% effective at reducing pulsatility. The EC exposed to low PP flow without PD exhibited distress signaling in the form of increased ERK1/2 phosphorylation (2.5 folds) when compared to those exposed to the same flow with PD. At high pump flow without PD, the cells detached and did not survive, while they were perfectly healthy with PD. Conclusions Flow pulsatility from PP causes EC distress at low flow and cell detachment at high flow. Elevated temporal shear stress gradient combined with elevated shear stress magnitude at high flow are believed to be the cause of cell detachment and death. The proposed PD design was effective at minimizing the hemodynamic stressors in the pump’s output, demonstrably reducing cell distress. Adoption of the proposed PD design in flow bioreactors should improve experimental protocols.
      PubDate: 2019-03-01
  • Technical Feasibility and Design of a Shape Memory Alloy Support Device to
           Increase Ejection Fraction in Patients with Heart Failure
    • Abstract: Purpose Heart failure is increasingly prevalent in the elderly. Treatment of patients with heart failure aims at improving their clinical condition, quality of life, prevent hospital (re)admissions and reduce mortality. Unfortunately, only a select group of heart failure patients with reduced ejection fraction are eligible for Cardiac Resynchronization Therapy where 30–40% remain non-responders and need left ventricular support. The aim of this study is to investigate if a shape memory alloy (SMA) is able to increase the ejection fraction of a mono-chamber static heart model by 5%. Methods A pediatric ventilation balloon was used as a heart model (mono-chamber). Flexinol®, a SMA, was placed around the heart model in multiple configurations and activated using pulse width modulation techniques to determine influence of diameter and configuration on volume displacement. Furthermore, pressure within the heart model was measured with a custom-made pressure sensor. Results SMA with a diameter of 0.38 mm, placed in a spiral shape and activated with a duty cycle of 80% and a frequency of 50/min gave the highest ejection fraction increase of 3.5%. Conclusions This study demonstrated the feasibility of volume displacement in a static heart model by activation of SMA-wires. Configuration, duty cycle, frequency, pulse intervals and diameter were identified as important factors affecting the activation of SMA-wires on volume displacement. Future research should include the use of parallel SMA-wires, prototype testing in dynamic or ex vivo bench models.
      PubDate: 2019-03-01
  • Abdominal Aortic Aneurysm Volumetric Evaluation During Mid-term Follow-Up
           After Endovascular Sealing Using the Nellix™ Device
    • Abstract: Objectives To analyze the volumetric evolution of abdominal aortic aneurysms after endovascular sealing (EVAS) with the Nellix™ device during follow-up. Methods Patients who underwent elective EVAS in our institution in 2014 and 2015 were retrospectively reviewed. Preoperative, postoperative and 1-year scans were processed. A custom software was conceived to assess semi-automated measurements of the aneurysm sac and the endograft sizes including volume, maximum diameter, sectional area and perimeter. Thrombus volume, aneurysm length, mean distance between the stents inside the polymer-filled sacs and endograft migration were also estimated. Manual maximum diameters were measured for comparison. Inter and intra-observer variability of the proposed semi-automated method was evaluated. Results Pre-EVAS, post-EVAS and last follow-up scans of 12 patients were finally analyzed during a mean follow-up of 17 ± 5 months. No endograft migration or endoleak were detected. During follow-up, aneurysm volume and perimeter slightly increased compared to post-EVAS scans (+ 1 and + 5%, respectively, p < 0.05). A systematic 6% enlargement of the endobag volume was also observed (range 1–15 mL, p < 0.001). Endobag maximum diameter, area and perimeter increased 4, 8, and 8%, respectively (all p < 0.01). Mean plane-by-plane distance between stents increased 4% (p < 0.05). Mean thrombus volume did not change during follow-up, although a high variability was observed. Aneurysm and thrombus volume changes were highly correlated (r = 0.93, p < 0.001). No associations were observed between aneurysm and endobag volume changes. Intra- and inter-observer variability was below 1.7 and 2.4% for diameter and volume measurements, respectively. The automated measurements of post-EVAS aneurysm diameter and volume were higher than preoperative (p < 0.05). Maximum diameters measured manually did not differ between scans. Conclusion Small aneurysm volume enlargement detected during a mid-term follow-up was associated with thrombus size change, whereas systematic endograft expansion resulted independent from the aortic growth. Volumetric measurements using a semi-automated method could quantify small changes in aneurysm, endograft and thrombus sizes not detected by manually defined maximal diameters.
      PubDate: 2019-03-01
  • Experimental Insight into the Hemodynamics and Perfusion of Radiological
           Contrast in Patent and Non-patent Aortic Dissection Models
    • Abstract: Purpose In a curved vessel such as the aortic arch, the velocity profile closer to the aortic root is normally skewed towards the inner curvature wall, while further downstream along the curve, the velocity profile becomes skewed towards the outer wall. In an aortic dissection (AD) disease, blood velocities in the true lumen (TL) and false lumen (FL) are hypothesized to depend on the proximity of the entry tear to the root of aortic arch. Faster velocity in the FL can lead to higher hemodynamic loading, and pose tearing risk. Furthermore, the luminal velocities control the perfusion rate of radiological contrast media during diagnostic imaging. The objective in this study is to investigate the effect of AD disease morphology and configuration on the blood velocity field in the TL and FL, and on the relative perfusion of radiological enhancement agents through the dissection. Methods Eight in vitro models were studied, including patent and non-patent FL configurations. Particle image velocimetry (PIV) was used to quantify the AD velocity field, while laser-induced fluorescence (LIF) was implemented to visualize dynamical flow phenomena and to quantify the perfusion of injected dye, in mimicry of contrast-enhanced computed tomography (CT). Results The location of the proximal entry tear along the aortic arch in a patent FL had a dramatic impact on whether the blood velocity was higher in the TL or FL. The luminal velocities were dependent on the entry/reentry tear size combination, with the smaller tear (whether distal or proximal) setting the upper limit on the maximal flow velocity in the FL. Upon merging near the distal reentry tear, the TL/FL velocity differential gave rise to the roll up and shedding of shear layer vortices that convected downstream in close proximity to the wall of the non-dissected aorta. In a non-patent FL, the flow velocity was practically null with all the blood passing through the TL. LIF imaging showed much slower perfusion of contrast dye in the FL compared to the TL. In a patent FL, however, dye had a comparable perfusion rate appearing around the same time as in the TL. Conclusions Blood velocities in the TL and FL were highly sensitive to the exact dissection configuration. Geometric case A1R, which had its proximal entry tear located further downstream along the aortic arch, and had its entry and reentry tears sufficiently sized, exhibited the highest FL flow velocity among the tested models, and it was also higher than in the TL, which suggest that this configuration had elevated hemodynamic loading and risk for tearing. In contrast-enhanced diagnostic imaging, a time-delayed acquisition protocol is recommended to improve the detection of suspected cases with a non-patent FL.
      PubDate: 2019-02-25
  • Current Challenges and Emergent Technologies for Manufacturing Artificial
           Right Ventricle to Pulmonary Artery (RV-PA) Cardiac Conduits
    • Abstract: Abstract Despite advances in modern surgery, congenital heart disease remains a medical challenge and major cause of infant mortality. Valved conduits are routinely used to surgically correct blood flow in hearts with congenital malformations by connecting the right ventricle to the pulmonary artery (RV-PA). This review explores the current range of RV-PA conduits and describes their strengths and disadvantages. Homografts and xenografts are currently the primary treatment modalities, however both graft types have limited biocompatibility and durability, and present a disease transmission risk. Structural deterioration of a replaced valve can lead to pulmonary valve stenosis and/or regurgitation. Moreover, as current RV-PA conduits are of a fixed size, multiple subsequent operations are required to upsize a valved conduit over a patient’s lifetime. We assess emerging biomaterials and tissue engineering techniques with a view to replicating the features of native tissues, including matching the durability and elasticity required for normal fluid flow dynamics. The benefits and limitations of incorporating cellular elements within the biomaterial are also discussed. Present review demonstrates that an alignment of medical and engineering disciplines will be ultimately required to produce a biocompatible and high-functioning artificial conduit.
      PubDate: 2019-02-14
  • Tricuspid Valve Annular Mechanics: Interactions with and Implications for
           Transcatheter Devices
    • Abstract: Abstract In the interventional treatment of tricuspid valve regurgitation, the majority of prosthetic devices interact with or are implanted to the tricuspid valve annulus. For new transcatheter technologies, there exists a growing body of clinical experience, literature, and professional discourse related to the difficulties in delivering, securing, and sustaining the function of these devices within the dynamic tricuspid annulus. Many of the difficulties arise from circumstances not encountered in open-heart surgery, namely; a non-arrested heart, indirect visualization, and a reliance on non-suture-based methods. These challenges require the application of procedural techniques or system designs to account for tricuspid annular motion, forces, and underlying tissue strength. Improved knowledge in these interactions will support the goals of improving device systems, their procedures, and patient outcomes. This review aims to describe current concepts of tricuspid annular mechanics, key device and procedural implications, and highlight current knowledge gaps for future consideration.
      PubDate: 2019-02-12
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Tel: +00 44 (0)131 4513762

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