Displaying publications 1 - 20 of 119 in total

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  1. Fulltext A perspective review on numerical simulations of hemodynamics in aortic dissection
    Wan Ab Naim WN, Ganesan PB, Sun Z, Chee KH, Hashim SA, Lim E
    ScientificWorldJournal, 2014;2014:652520.
    PMID: 24672348 DOI: 10.1155/2014/652520
    Aortic dissection, characterized by separation of the layers of the aortic wall, poses a significant challenge for clinicians. While type A aortic dissection patients are normally managed using surgical treatment, optimal treatment strategy for type B aortic dissection remains controversial and requires further evaluation. Although aortic diameter measured by CT angiography has been clinically used as a guideline to predict dilation in aortic dissection, hemodynamic parameters (e.g., pressure and wall shear stress), geometrical factors, and composition of the aorta wall are known to substantially affect disease progression. Due to the limitations of cardiac imaging modalities, numerical simulations have been widely used for the prediction of disease progression and therapeutic outcomes, by providing detailed insights into the hemodynamics. This paper presents a comprehensive review of the existing numerical models developed to investigate reasons behind tear initiation and progression, as well as the effectiveness of various treatment strategies, particularly the stent graft treatment.
    Matched MeSH terms: Hemodynamics*
  2. Functional Near-Infrared Spectroscopy of English-Speaking Adults With Attention-Deficit/Hyperactivity Disorder During a Verbal Fluency Task
    Husain SF, Chiang SK, Vasu AA, Goh CP, McIntyre RS, Tang TB, et al.
    J Atten Disord, 2023 Nov;27(13):1448-1459.
    PMID: 37341192 DOI: 10.1177/10870547231180111
    OBJECTIVE: Functional near-infrared spectroscopy (fNIRS) provides direct and quantitative assessment of cortical hemodynamic response. It has been used to identify neurophysiological alterations in medication-naïve adults with attention-deficit/hyperactivity disorder (ADHD). Hence, this study aimed to distinguish both medication-naïve and medicated adults with ADHD from healthy controls (HC).

    METHOD: 75 HCs, 75 medication-naïve, and 45 medicated patients took part in this study. fNIRS signals during a verbal fluency task (VFT) were acquired using a 52-channel system and relative oxy-hemoglobin changes in the prefrontal cortex were quantified.

    RESULTS: Prefrontal cortex hemodynamic response was lower in patients than HCs (p ≤ ≤.001). Medication-naïve and medicated patients did not differ in hemodynamic response or symptom severity (p > .05). fNIRS measurements were not associated with any clinical variables (p > .05). 75.8% patients and 76% HCs were correctly classified using hemodynamic response.

    CONCLUSION: fNIRS may be a potential diagnostic tool for adult ADHD. These findings need to be replicated in larger validation studies.

    Matched MeSH terms: Hemodynamics/physiology
  3. Pesticides Exposure and Cardiovascular Hemodynamic Parameters Among Male Workers Involved in Mosquito Control in East Coast of Malaysia
    Samsuddin N, Rampal KG, Ismail NH, Abdullah NZ, Nasreen HE
    Am J Hypertens, 2016 Feb;29(2):226-33.
    PMID: 26112865 DOI: 10.1093/ajh/hpv093
    Research findings have linked exposure to pesticides to an increased risk of cardiovascular (CVS) diseases. Therefore, this study aimed to assess the impact of chronic mix-pesticides exposure on CVS hemodynamic parameters.
    Matched MeSH terms: Hemodynamics
  4. METOPROLOL SUCCINATE: GENETIC ASPECTS OF INDIVIDUAL SENSITIVITY AND EFFICACY IN PATIENTS WITH OBESITY AND CHRONIC HEART FAILURE
    Gasanov I, Rudyk Y
    Georgian Med News, 2019 Jan.
    PMID: 30829590
    Aim - optimization of the treatment of obesity and chronic heart failure (CHF) patients by identifying key factors for the progression of cardiac decompensation and the principles of using metoprolol succinate, taking into account pharmacogenetic aspects in the complex treatment of this comorbidity. 127 patients with CHF 2nd-3rd stages, 1st-4th functional class by New York Heart Association at the age of 32-87 (61 [57; 65]) years were examined, including 93 men and 34 women. A comparative analysis of certain clinical criteria using the sequential analysis of Wald A.A. The results were statistically plausible with p<0.05. Conducting factor analysis allowed to separate groups of indicators and estimate the specific weight of individual factors in the pathogenesis of combined pathology - obesity and heart failure. The first two factors determine 76.8% of the variability of the indicators, given the indicators that load them, they were given descriptive titles "clinical-hemodynamic factor", "clinical and anthropometric factor". The proposed prognostic protocol provides new possibilities for predicting the efficacy of metoprolol succinate in patients with obesity and chronic heart failure. The developed discriminatory models allow to objectify the criteria for determining the doses of metoprolol succinate in patients with obesity and chronic heart failure - the maximum initial, maximal endpoint, and also to evaluate the expediency of a subsequent stepwise increase in dose. Perspective of further studies - development and clinical approbation of the protocol of the use of metoprolol succinate in patients with CHF in the context of obesity, taking into account the results of the conducted factor analysis and developed prognostic means.
    Matched MeSH terms: Hemodynamics
  5. The influence of geometrical shapes of stenosis on the blood flow in stenosed artery
    Kamangar S, Nik-Ghazali N, Badarudin A, Ameer Ahamad N, Irfan Anjum Badruddin, Govindaraju K, et al.
    Sains Malaysiana, 2017;46:1923-1933.
    The present work was carried out to investigate the blood flow behavior and the severity of blockage caused in the
    arterial passage due to the different geometries such as elliptical, trapezium and triangular shapes of stenosis. The study
    was conducted with respect to various sizes of stenosis in terms of 70%, 80% and 90% area blockage of the arterial
    blood flow. The study was carried out numerically with the help of advance computational fluid dynamic software. It
    was found that the shape of the stenosis plays an important role in overall pressure drop across the blockage region
    of artery. The highest level of pressure drop was observed for trapezoidal shape of stenosis followed by elliptical and
    then by triangular shaped stenosis. The wall shear stress across the stenosis is great for trapezoidal shape followed by
    triangular and elliptical stenosis for same blockage area in the artery.
    Matched MeSH terms: Hemodynamics
  6. Shear Wave Elastography: A Review on the Confounding Factors and Their Potential Mitigation in Detecting Chronic Kidney Disease
    Lim WTH, Ooi EH, Foo JJ, Ng KH, Wong JHD, Leong SS
    Ultrasound Med Biol, 2021 08;47(8):2033-2047.
    PMID: 33958257 DOI: 10.1016/j.ultrasmedbio.2021.03.030
    Early detection of chronic kidney disease is important to prevent progression of irreversible kidney damage, reducing the need for renal transplantation. Shear wave elastography is ideal as a quantitative imaging modality to detect chronic kidney disease because of its non-invasive nature, low cost and portability, making it highly accessible. However, the complexity of the kidney architecture and its tissue properties give rise to various confounding factors that affect the reliability of shear wave elastography in detecting chronic kidney disease, thus limiting its application to clinical trials. The objective of this review is to highlight the confounding factors presented by the complex properties of the kidney, in addition to outlining potential mitigation strategies, along with the prospect of increasing the versatility and reliability of shear wave elastography in detecting chronic kidney disease.
    Matched MeSH terms: Hemodynamics
  7. Fulltext Pressure reduction on blood flow in aorta coronary sinus conduit
    Siti Aslina Hussain, Tan, Hong Tat, Mohd Ismail Abdul Hamid, Norhafizah Abdullah, Azni Idris
    Pertanika Journal of Science & Technology, 2012;20(2):347-353.
    MyJurnal
    Numerical studies of blood flow system of aorta coronary sinus conduit were carried out using ANSYSTMCFD simulation. A different model of conduit, which differs in the inlet diameter, was investigated. Theinvestigated inlet diameters are 3 mm, 4 mm and 5 mm. Pressure drop from 80 mmHg to 15 mmHgwas achieved for all the models. The comparison chart was produced to compare the pattern of pressurereduction as well as velocity distribution in each model. From the analysis of coronary sinus conduit,it was found that a narrow tube needs to be incorporated into the conduit produced. This is to inducea venturi effect to reduce the pressure drop of blood within a specific throat length. As conclusion, amodel of 3 mm inlet and a throat diameter of 1.13 mm show satisfactory result for pressure reductionfrom 80 mmHg to 15 mmHg. This particular model also has a lower peak velocity at the inlet zone ofthe throat section, which is more preferable in terms of Reynolds number.
    Matched MeSH terms: Hemodynamics
  8. Fulltext Role of Transcranial Doppler in the Evaluation of Vasculopathy in Tuberculous Meningitis
    Tai MS, Sharma VK
    PLoS One, 2016;11(10):e0164266.
    PMID: 27723828 DOI: 10.1371/journal.pone.0164266
    Vascular complications are important causes of cerebral infarction in tuberculous meningitis (TBM).Transcranial Doppler ultrasonography (TCD) is a non-invasive tool that can provide real-time information about cerebral hemodynamics. However, the literature on the role of TCD in the diagnosis or monitoring of vasculopathy associated with TBM is scarce. We explored the role of TCD in the diagnosis and monitoring of TBM-related vasculopathy of the major intracranial arteries.
    Matched MeSH terms: Hemodynamics
  9. Fulltext 3D model of generalized power law blood flow in a stenosed bifurcated artery
    Azim Azahari, Zuhaila Ismail, Normazni Abdullah
    MATEMATIKA, 2018;34(1):87-102.
    MyJurnal
    Numerical simulation of the behaviour of blood flow through a stenosed bifurcated
    artery with the presence of single mild stenosis at parent artery is investigated. The
    flow analysis applies the incompressible, steady, three-dimensional Navier-Stokes equations
    for non-Newtonian generalized power law fluids. Behaviour of blood flow is simulated
    numerically using COMSOL Multiphysicsthat based on finite element method.The
    results showthe effect of severity of stenosis on flow characteristics such as axial velocity
    and its exhibit flow recirculation zone for analysis on streamlines pattern.
    Matched MeSH terms: Hemodynamics
  10. Fulltext The impact of cranioplasty on cerebral blood flow and its correlation with clinical outcome in patients underwent decompressive craniectomy
    Mah JK, Kass RA
    Asian J Neurosurg, 2016 Jan-Mar;11(1):15-21.
    PMID: 26889273 DOI: 10.4103/1793-5482.172593
    Decompressive craniectomy is commonly use as the treatment for medically refractory intracranial hypertension. Unexpected improvement in patient's neurological status has been observed among patients that underwent cranioplasty. Restoration of cerebral blood flow (CBF) hemodynamics is one of the contributing factors. This study was conducted to determine the impact of cranioplasty on CBF and its correlation with clinical outcome.
    Matched MeSH terms: Hemodynamics
  11. Fulltext Prevalence of Bacterial Contamination when using a Diversion Pouch during Blood Collection: A Single Center Study in Malaysia
    Jumaah N, Joshi SR, Sandai D
    Malays J Med Sci, 2014 May;21(3):47-53.
    PMID: 25246835 MyJurnal
    The implementation of diversion pouches is to minimise the risk of bacterial contamination as the initial blood flow is prevented from entering primary bag collections as it is diverted into a pouch. This study was carried out to determine the prevalence of bacterial contamination in the diversion pouches used during blood collections in the Transfusion Department of Hospital Seberang Jaya, Penang, Malaysia.
    Matched MeSH terms: Hemodynamics
  12. Hemodynamic response to exercise and head-up tilt of patients implanted with a rotary blood pump: a computational modeling study
    Lim E, Salamonsen RF, Mansouri M, Gaddum N, Mason DG, Timms DL, et al.
    Artif Organs, 2015 Feb;39(2):E24-35.
    PMID: 25345482 DOI: 10.1111/aor.12370
    The present study investigates the response of implantable rotary blood pump (IRBP)-assisted patients to exercise and head-up tilt (HUT), as well as the effect of alterations in the model parameter values on this response, using validated numerical models. Furthermore, we comparatively evaluate the performance of a number of previously proposed physiologically responsive controllers, including constant speed, constant flow pulsatility index (PI), constant average pressure difference between the aorta and the left atrium, constant average differential pump pressure, constant ratio between mean pump flow and pump flow pulsatility (ratioP I or linear Starling-like control), as well as constant left atrial pressure ( P l a ¯ ) control, with regard to their ability to increase cardiac output during exercise while maintaining circulatory stability upon HUT. Although native cardiac output increases automatically during exercise, increasing pump speed was able to further improve total cardiac output and reduce elevated filling pressures. At the same time, reduced venous return associated with upright posture was not shown to induce left ventricular (LV) suction. Although P l a ¯ control outperformed other control modes in its ability to increase cardiac output during exercise, it caused a fall in the mean arterial pressure upon HUT, which may cause postural hypotension or patient discomfort. To the contrary, maintaining constant average pressure difference between the aorta and the left atrium demonstrated superior performance in both exercise and HUT scenarios. Due to their strong dependence on the pump operating point, PI and ratioPI control performed poorly during exercise and HUT. Our simulation results also highlighted the importance of the baroreflex mechanism in determining the response of the IRBP-assisted patients to exercise and postural changes, where desensitized reflex response attenuated the percentage increase in cardiac output during exercise and substantially reduced the arterial pressure upon HUT.
    Matched MeSH terms: Hemodynamics*
  13. Fulltext Hemodynamic monitoring and outcome-a physiological appraisal
    Chan YK, Khan ZH
    Acta Anaesthesiol Taiwan, 2011 Dec;49(4):154-8.
    PMID: 22221689 DOI: 10.1016/j.aat.2011.11.002
    Hemodynamic monitoring provides us with refined details about the cardiovascular system. In spite of increased availability of the monitoring process and monitoring equipment, hemodynamic monitoring has not significantly improved survival outcome. Care providers should be cognizant of the role of the cardiovascular system and its importance in oxygen delivery to the cells in order to sustain life. Effective hemodynamic monitoring should be able to delineate how well the system is performing in carrying out this role. Different hemodynamic monitors serve in this role to a different extent; some provide very little information on this. The cardiovascular system is only one of the many systems that need to function optimally for survival; others of equal importance include the integrity of the airway, the breathing process, the adequacy of hemoglobin level, and the health of the tissue bed, especially in the brain and the heart. Advances in hemodynamic monitoring with focus on oxygen delivery at the cellular level may ultimately provide the edge to effective monitoring that can impact outcome.
    Matched MeSH terms: Hemodynamics/physiology*
  14. Severe mitral incompetence following balloon mitral valvuloplasty: complete resolution during follow-up
    Kannan P, Jeyamalar R
    Cathet Cardiovasc Diagn, 1995 Mar;34(3):220-1; discussion 222-3.
    PMID: 7497488
    Mitral incompetence (MR) is a complication of balloon mitral valvuloplasty. There are few reports of long-term outcome. We believe this is the first report in the literature of complete resolution during follow-up of severe mitral regurgitation resulting from balloon valvuloplasty.
    Matched MeSH terms: Hemodynamics/physiology
  15. Fulltext Right heart haemodynamics in normal Malaysian subjects
    Omar A, Fong CY, Singham KT
    Med J Malaysia, 1985 Dec;40(4):307-11.
    PMID: 3842730
    The right heart pressures and saturations at different sites were measured in 87 normal individuals over a 16-year period during heart cardiac catheterisation. The right heart pressure measurements were comparable with normal values reported in Caucasian subjects. However, the total pulmonary vascular resistance and systemic vascular resistance were significantly different, though the pulmonary vascular resistance was comparable.
    Matched MeSH terms: Hemodynamics*
  16. Fulltext Numerical solution of magnetohydrodynamics effects on a generalised power law fluid model of blood flow through a bifurcated artery with an overlapping shaped stenosis
    Zain NM, Ismail Z
    PLoS One, 2023;18(2):e0276576.
    PMID: 36780455 DOI: 10.1371/journal.pone.0276576
    This paper presents a numerical analysis of blood flow in a diseased vessel within the presence of an external magnetic field. The blood flow was considered to be incompressible and fully developed, in that the non-Newtonian nature of the fluid was characterised as a generalised power law model for shear-thinning, Newtonian, and shear-thickening fluids. The impact of a transverse directed external magnetic field on blood flow through a stenosed bifurcated artery was investigated. The arterial geometry was considered as a bifurcated channel with overlapping shaped stenosis. The problem was treated mathematically using the Galerkin Least-Squares (GLS) method. The implementation of this numerical method managed to overcome the numerical instability faced by the classical Galerkin technique when adopted to a highly viscous flow. The benefit of GLS in circumventing the Ladyzhenskaya-Babuška-Brezzi (LBB) condition was utilized by evaluating both the velocity and pressure components at corner nodes of a unstructured triangular element. The non-linearity that emerged from the convective terms was then treated using the Newton-Raphson method, while the numerical integrals were computed using a Gaussian quadrature rule with six quadrature points. The findings obtained from this study were then compared with available results from the literature as well as Comsol multiphysics software to verify the accuracy and validity of the numerical algorithms. It was found that the application of magnetic field was able to overcome flow reversal by 39% for a shear-thinning fluid, 26% for a Newtonian fluid, and 27% for a shear-thickening fluid. The negative pressure and steep wall shear stress which occurs at the extremities of an overlapping stenosis throat were diminished by rise in magnetic intensity. This prevented thrombosis occurrence and produced a uniform calm flow.
    Matched MeSH terms: Hemodynamics*
  17. Fulltext Cardiorespiratory parameters before and after acupuncture: observations in a healthy and diseased state
    Mohan V, Das S
    Clinics (Sao Paulo), 2012;67(6):673-4.
    PMID: 22760909
    Comment on: Nascimento RC, Hossri CA, Berwanger O, Carvalho VO. Acupuncture and exercise capacity: a case report. Clinics. 2012;67(2):193–4
    Matched MeSH terms: Hemodynamics/physiology*
  18. Coupled Plasma Filtration Adsorption (CPFA) plus Continuous Veno-Venous Haemofiltration (CVVH) versus CVVH alone as an adjunctive therapy in the treatment of sepsis
    Hassan J, Cader RA, Kong NC, Mohd M, Rahman AR, Hod R
    EXCLI J, 2013;12:681-92.
    PMID: 26600735
    To compare the efficacy of Coupled Plasma Filtration and Adsorption (CPFA) plus Continuous Veno-Venous Haemofiltration (CVVH) versus CVVH alone as an adjunct treatment of sepsis in terms of haemodynamic stability, inotropic requirement and inflammatory mediators.
    Matched MeSH terms: Hemodynamics
  19. Hartmann and Reynolds numbers effects in the newtonian blood flow of a bifurcated artery with an overlapping stenosis
    Norliza Mohd. Zain, Zuhaila Ismail
    MATEMATIKA, 2019;35(2):213-227.
    MyJurnal
    Blood flow through a bifurcated artery with the presence of an overlapping stenosis located at parent’s arterial lumen under the action of a uniform external magnetic field is studied in this paper. Blood is treated as an electrically conducting fluid which exhibits the Magnetohydrodynamics principle and it is characterized by a Newtonian fluid model. The governing equations are discretized using a stabilization technique of finite element known as Galerkin least-squares. The maximum velocity and pressure drop evaluated in this present study are compared with the results found in previous literature and COMSOL Multiphysics. The solutions found in a satisfactory agreement, thus verify the source code is working properly. The effects of dimensionless parameters of Hartmann and Reynolds numbers in the fluid’s velocity and pressure are examined in details with further scientific discussions.
    Matched MeSH terms: Hemodynamics
  20. Effect of intimal flap motion on flow in acute type B aortic dissection by using fluid-structure interaction
    Chong MY, Gu B, Chan BT, Ong ZC, Xu XY, Lim E
    Int J Numer Method Biomed Eng, 2020 12;36(12):e3399.
    PMID: 32862487 DOI: 10.1002/cnm.3399
    A monolithic, fully coupled fluid-structure interaction (FSI) computational framework was developed to account for dissection flap motion in acute type B aortic dissection (TBAD). Analysis of results included wall deformation, pressure, flow, wall shear stress (WSS), von Mises stress and comparison of hemodynamics between rigid wall and FSI models. Our FSI model mimicked realistic wall deformation that resulted in maximum compression of the distal true lumen (TL) by 21.4%. The substantial movement of intimal flap mostly affected flow conditions in the false lumen (FL). Flap motion facilitated more flow entering the FL at peak systole, with the TL to FL flow split changing from 88:12 in the rigid model to 83:17 in the FSI model. There was more disturbed flow in the FL during systole (5.8% FSI vs 5.2% rigid) and diastole (13.5% FSI vs 9.8% rigid), via a λ2 -criterion. The flap-induced disturbed flow near the tears in the FSI model caused an increase of local WSS by up to 70.0% during diastole. This resulted in a significant reduction in the size of low time-averaged WSS (TAWSS) regions in the FL (113.11 cm2 FSI vs 177.44 cm2 rigid). Moreover, the FSI model predicted lower systolic pressure, higher diastolic pressure, and hence lower pulse pressure. Our results provided new insights into the possible impact of flap motion on flow in aortic dissections, which are particularly important when evaluating hemodynamics of acute TBAD. NOVELTY STATEMENT: Our monolithic fully coupled FSI computational framework is able to reproduce experimentally measured range of flap deformation in aortic dissection, thereby providing novel insights into the influence of physiological flap motion on the flow and pressure distributions. The drastic flap movement increases the flow resistance in the true lumen and causes more disturbed flow in the false lumen, as visualized through the λ2 criterion. The flap-induced luminal pressure is dampened, thereby affecting pressure measures, which may serve as potential prognostic indicators for late complications in acute uncomplicated TBAD patients.
    Matched MeSH terms: Hemodynamics
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