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Research Interests: Treatment Outcome, Optical coherence tomography, Medicine, Stents, Prospective studies, and 15 moreHumans, Female, Male, Follow-up studies, Vascular endothelium, Middle Aged, Mechanical Stress, Coronary Angiography, Cardiovascular Imaging, Reproducibility of Results, prosthesis Design, Neointima, Cohort Studies, Cardiovascular medicine and haematology, and Tissue Scaffolds
Low density lipoprotein (LDL) has a significant role on the atherosclerotic plaque development, while the concentration of high density lipoproteins (HDL) is considered to play an atheroprotective role according to several biochemical... more
Low density lipoprotein (LDL) has a significant role on the atherosclerotic plaque development, while the concentration of high density lipoproteins (HDL) is considered to play an atheroprotective role according to several biochemical mechanisms. In this work, it is the first time that both LDL and HDL concentrations are taken into account in order to predict the regions prone for plaque development. Our modeling approach is based on the use of a realistic three-dimensional reconstructed pig coronary artery in two time points. Biochemical data measured in the pig were also included in order to develop a more customized model. We modeled coronary blood flow by solving the Navier-Stokes equations in the arterial lumen and plasma filtration in the arterial wall using Darcy's Law. HDL transport was modeled only in the arterial lumen using the convection-diffusion equation, while LDL transport was modeled both in the lumen and the arterial wall. An additional novelty of this work is that we model the oxidation of LDL taking into account the atheroprotective role of HDL. The results of our model were in good agreement with histological findings demonstrating that increased oxidized LDL is found near regions of advanced plaques, while non-oxidized LDL is found in regions of early plaque types.
Research Interests: Biochemistry, Computer Science, Chemistry, Cardiology, Convection, and 15 moreMass Transfer, Computational Modeling, Molecular Biophysics, Medicine, Humans, Diffusion, Animals, Behavioral Animal Models, Mathematical Model, Haemodynamics, Coronary Angiography, Oxygen, Oxidation, Convection Diffusion Equation, and Coronary Vessels
To examine the efficacy of angiography derived endothelial shear stress (ESS) in predicting atherosclerotic disease progression. Thirty-five patients admitted with ST-elevation myocardial infarction that had three-vessel intravascular... more
To examine the efficacy of angiography derived endothelial shear stress (ESS) in predicting atherosclerotic disease progression. Thirty-five patients admitted with ST-elevation myocardial infarction that had three-vessel intravascular ultrasound (IVUS) immediately after revascularization and at 13 months follow-up were included. Three dimensional (3D) reconstruction of the non-culprit vessels were performed using (i) quantitative coronary angiography (QCA) and (ii) methodology involving fusion of IVUS and biplane angiography. In both models, blood flow simulation was performed and the minimum predominant ESS was estimated in 3 mm segments. Baseline plaque characteristics and ESS were used to identify predictors of atherosclerotic disease progression defied as plaque area increase and lumen reduction at follow-up. Fifty-four vessels were included in the final analysis. A moderate correlation was noted between ESS estimated in the 3D QCA and the IVUS-derived models (r = 0.588, P < ...
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Purpose: To study the dose and time effect of external beam irradiation on the morphometry of both angioplasted and nonangioplasted arteries in a hypercholesterolemic rabbit model. Methods and materials: Eight groups of rabbit femoral... more
Purpose: To study the dose and time effect of external beam irradiation on the morphometry of both angioplasted and nonangioplasted arteries in a hypercholesterolemic rabbit model. Methods and materials: Eight groups of rabbit femoral arteries were studied: arteries (a) with no intervention, (b) irradiated with a 12-Gy 6 MV X-ray dose, (c) with a 18-Gy, (d) treated with balloon angioplasty,
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Research Interests: Algorithms, Calcium, Optical coherence tomography, Optical Imaging, Tomography, and 13 moreImage Classification, Humans, Cluster Analysis, Coherence, Diagnostic Imaging, High resolution satelite image, Sensitivity, Reproducibility of Results, K means algorithm, Sensitivity and Specificity, Predictive value of tests, image resolution, and Coronary Vessels
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Heart failure (HF) is a chronic disease associated with significant prevalence, mortality, and health care expenditure. The aim of the present study was to explore the factors associated with anxiety and depression experienced by patients... more
Heart failure (HF) is a chronic disease associated with significant prevalence, mortality, and health care expenditure. The aim of the present study was to explore the factors associated with anxiety and depression experienced by patients hospitalized with HF. We evaluated 190 hospitalized HF patients in four public hospitals. The data were collected using a specific questionnaire, which, apart from demographic and clinical variables, included the Hospital Anxiety and Depression Scale (HADS). In the total sample, 24.7% and 32.6% of patients were found to have moderate or high levels of anxiety, respectively. Simple multinomial logistic regression showed that no characteristic was significantly associated with anxiety. It also appeared that 17.4% of patients had minor and 24.2% major depression. Among the factors examined, longer disease duration was associated with a higher probability of being depressed (p=0.041). Moreover, single/divorced and widowed patients were more likely to have major depression compared to married patients (35.6% vs. 19.2%, p=0.046). Simple multinomial logistic regression revealed that married patients were 59% less likely to have major depression compared to their unmarried counterparts (OR: 0.41). Moreover, patients with short (&amp;amp;amp;amp;amp;amp;amp;amp;lt;1 year) and moderate (2-5 years) disease duration were 69% (OR: 0.31) and 61% (OR: 0.39) less likely to have major depression compared to those with a long disease duration. Multiple multinomial logistic regression showed that only the disease duration remained statistically significantly associated with depression after controlling for the rest of factors found to be significant at a univariate level. Nurses and physicians must take measures for the identification, assessment and management of anxiety and depression in this clinical population.
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The aim of this study is to describe a new method for three-dimensional (3D) reconstruction of coronary arteries using Frequency Domain Optical Coherence Tomography (FD-OCT) images. The rationale is to fuse the information about the... more
The aim of this study is to describe a new method for three-dimensional (3D) reconstruction of coronary arteries using Frequency Domain Optical Coherence Tomography (FD-OCT) images. The rationale is to fuse the information about the curvature of the artery, derived from biplane angiographies, with the information regarding the lumen wall, which is produced from the FD-OCT examination. The method is based on a three step approach. In the first step the lumen borders in FD-OCT images are detected. In the second step a 3D curve is produced using the center line of the vessel from the two biplane projections. Finally in the third step the detected lumen borders are placed perpendicularly onto the path based on the centroid of each lumen border. The result is a 3D reconstructed artery produced by all the lumen borders of the FD-OCT pullback representing the 3D arterial geometry of the vessel.
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Optical Coherence Tomography (OCT) is a fiber--optic imaging modality which produces high resolution tomographic images of the coronary lumen and outer vessel wall. While OCT images present morphological information in highly resolved... more
Optical Coherence Tomography (OCT) is a fiber--optic imaging modality which produces high resolution tomographic images of the coronary lumen and outer vessel wall. While OCT images present morphological information in highly resolved detail, the characterization of the various plaque components relies on trained readers. The aim of this study is to extract a set of features in grayscale OCT images and to use them in order to classify the atherosclerotic plaque. Intensity and texture based features we used in order to classify the plaque in four plaque types: Calcium (C), Lipid Pool (LP), Fibrous Tissue (FT) and Mixed Plaque (MP). 50 OCT annotated images from 3 patients were used to train and test the proposed plaque characterization method. Using a Random Forests classifier overall classification accuracy 80.41% is reported.
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ABSTRACT Shear stress on the endothelial surface has been implicated in atherosclerosis localization, plaque vulnerability, and remodeling behavior of the arterial wall, as well as in-stent restenosis following percutaneous coronary... more
ABSTRACT Shear stress on the endothelial surface has been implicated in atherosclerosis localization, plaque vulnerability, and remodeling behavior of the arterial wall, as well as in-stent restenosis following percutaneous coronary interventions. The purposes of this chapter are to introduce haemodynamic shear stress, briefly explain the methodology for measuring and imaging shear stress in vivo, present the role of shear stress in the atherosclerotic disease process, and cite the evidence highlighting the effects of stent implantation on local blood flow patterns and linking shear stress at the stent surface to neointimal hyperplasia following coronary artery stenting.
ABSTRACT Optical coherence tomography (OCT) is a relatively new imaging technique that was introduced to overcome limitations of previous imaging modalities. OCT provides high resolution cross-sectional images of the coronaries which... more
ABSTRACT Optical coherence tomography (OCT) is a relatively new imaging technique that was introduced to overcome limitations of previous imaging modalities. OCT provides high resolution cross-sectional images of the coronaries which permit detailed evaluation of the luminal morphology and assessment of coronary artery pathology. These unique qualities render OCT a useful tool in clinical practice and research arena. However, apart from its significant advantages OCT imaging has also considerable limitations. To overcome the pitfalls of OCT, fusion of this modality with other imaging techniques has been proposed. Today several hybrid catheter and sophisticated data fusion methodologies have been developed for this purpose, which appear to provide a complete and comprehensive assessment of plaque characteristics and vessel pathophysiology. The aim of this review article is to describe the available OCT based hybrid imaging modalities, present the advantages and limitations of these approaches and discuss their potential value in clinical practice and research arena.
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The electrocardiogram (ECG) is a signal commonly used in medicine mainly because of its simple acquisition process and the diagnostic information that can be extracted concerning the pathophysiological condition of the heart. It... more
The electrocardiogram (ECG) is a signal commonly used in medicine mainly because of its simple acquisition process and the diagnostic information that can be extracted concerning the pathophysiological condition of the heart. It represents the electrical activity of the heart in the surface of the ...
In this paper, a framework for the inflation of micro-CT data using intravascular ultrasound (IVUS) images, is presented. The proposed methodology consists of four steps. In the first step a centerline is extracted from the micro-CT... more
In this paper, a framework for the inflation of micro-CT data using intravascular ultrasound (IVUS) images, is presented. The proposed methodology consists of four steps. In the first step a centerline is extracted from the micro-CT images. In the second step the micro CT images are segmented automatically using the k-means algorithm. In the third step IVUS- micro-CT images are co-registered based on fiducial markers selected manually by the experts. Finally, the images are inflated by applying a transformation method on each image. The transformation method is based on the IVUS and micro-CT contour difference. The proposed methodology for inflating micro-CT images could increase the reliability of correct plaque labeling process as well to enhance the accuracy of the produced training dataset from the micro-CT images.
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Cardiovascular disease, including coronary artery disease, stroke and peripheral vascular disease, is the leading cause of death among women. Vascular endothelial dysfunction is an early marker of atherosclerosis. Women with premature... more
Cardiovascular disease, including coronary artery disease, stroke and peripheral vascular disease, is the leading cause of death among women. Vascular endothelial dysfunction is an early marker of atherosclerosis. Women with premature ovarian failure (or premature menopause) present an increased risk for cardiovascular disease, which might be attributed to the early onset of vascular endothelial dysfunction, associated with sex steroid deficiency. Cyclical estrogen and progestogen therapy has been shown to restore endothelial function in these young women. Further research is required to assess primarily the long-term effects of hormone replacement therapy on cardiovascular and overall prognosis in young women with premature ovarian failure, as well as the effects of different doses, duration and routes of hormone administration in these women.
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Endovascular brachytherapy (EVBT) is an established treatment to reduce the probability of restenosis after a percutaneous coronary intervention. The purpose of this study was to assess (1) the manufacturer&#39;s stated dosimetric... more
Endovascular brachytherapy (EVBT) is an established treatment to reduce the probability of restenosis after a percutaneous coronary intervention. The purpose of this study was to assess (1) the manufacturer&#39;s stated dosimetric data for (90)Sr/(90)Y source trains to be used in EVBT and (2) the procedure-related radiation burden. The radiation fields in water around six (90)Sr/(90)Y source trains were studied using phantoms made of &#39;solid water&#39; and MD55-2 radiochromic films. The water equivalence of the phantom material was tested by applying quantitative computed tomography. Thermoluminescence dosemeters were used to assess personal radiation burden and crosscheck the dose distribution along the source trains. Technical failure was observed in one source train and this train was excluded from analysis. The measured dose rate in water at 2 mm radial distance was on average 8% higher than the manufacture&#39;s stated value (range of measured to stated values 1.05--1.15). The dose rate decreased exponentially with radial distance between 2 and 6 mm. The dose rate in contact with the source viewing window of the delivery devices ranged between 0.5 and 7.5 mGy h(-1). Low-energy photons were the main contributors to personal dose.
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Research Interests: Research Design, Atherosclerosis, Preventive medicine, Adolescent, Pediatric Cardiology, and 13 moreGreece, Humans, Child, Female, Male, Vascular endothelium, Prognosis, The Carotid Artery Intima Media Thickness, Cross Sectional Studies, Vasodilation, Early Diagnosis, Age of Onset, and Brachial artery
Macrophages interact with modified lipoproteins and alter their functional status. In this study, the effects of the adrenergic agents adrenaline, isoproterenol, and dobutamine on macrophages activated with acetylated low-density... more
Macrophages interact with modified lipoproteins and alter their functional status. In this study, the effects of the adrenergic agents adrenaline, isoproterenol, and dobutamine on macrophages activated with acetylated low-density lipoprotein were tested. The aim of this investigation was to determine whether adrenergic agents influence biologically significant functions of these cells in an in vitro model of macrophage-lipoprotein acute interaction. Rat peritoneal macrophages were incubated with acetylated low-density lipoprotein for 16 h, with or without adrenergic agents. Hydrogen peroxide and nitric oxide production and acid phosphatase activities in the supernatant and cell lysate were assayed. Adrenaline and isoproterenol inhibited the production of hydrogen peroxide, stimulated the production of nitric oxide, and increased the extracellular activity of acid phosphatase in the lipoprotein-activated cells. Dobutamine increased the extracellular, but decreased the intracellular acid phosphatase activity. Adrenaline and dobutamine also produced changes in the cell size and nuclear morphology of the macrophages. Macrophages are activated in vitro by acetylated low-density lipoprotein, and their functions and morphology are modified under the influence of adrenergic agents. Certain effects could be attributed to changes in cyclic AMP levels.
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The objective of this article is to study which factors are associated with depression and anxiety in older adults with intellectual disabilities (ID). Depressive and anxiety symptoms were studied in 990 participants with borderline to... more
The objective of this article is to study which factors are associated with depression and anxiety in older adults with intellectual disabilities (ID). Depressive and anxiety symptoms were studied in 990 participants with borderline to profound ID, aged ≥ 50 years, using self-report and informant-report screening questionnaires. In 290 participants, major depression and anxiety disorders were assessed with a standardised psychiatric interview. Associations with personal, medical and psychosocial factors, which were collected through questionnaires and participants&amp;amp;amp;amp;#39; medical and psychological records, were studied using multiple logistic regression analysis. Increased depressive symptoms were positively associated with increased anxiety symptoms, number of life events during the past year and chronic diseases (heart failure, stroke, chronic obstructive pulmonary disease, coronary artery disease, diabetes mellitus and malignity in the previous 5 years) and negatively with instrumental activities of daily living (IADL) abilities. Major depression was positively associated with chronic diseases and negatively with IADL abilities. Increased anxiety symptoms were positively associated with borderline or mild ID and increased depressive symptoms and negatively associated with Down syndrome, epilepsy and social contacts. Anxiety disorders showed no significant associations. To develop effective prevention and treatment policies, factors associated with depression and anxiety in older adults with ID should be further examined in longitudinal research.
Research Interests: Psychology, Cognitive Science, Anxiety Disorders, Quality of life, Intellectual Disability, and 22 moreAnxiety, Activities of Daily Living, Greece, TIME, Heart Failure, Humans, Hospitalization, Chronic Disease, Female, Male, Netherlands, Depressive Disorder, Risk factors, Clinical Sciences, Geriatric Psychiatry, Aged, Middle Aged, Risk Factors, Time, ANXIETY, Life Change Events, and Marital Status
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Research Interests: Artificial Intelligence, Biomedical Engineering, Data Mining, Biomedical, Electrocardiography, and 13 moreHumans, Noise, Association Rule Mining, Heart rate, Feature Extraction, Information Storage and Retrieval, Cardiac Arrhythmias, Electrocardiogram, Reproducibility of Results, Association Rule, Sensitivity and Specificity, Rule Based, and Electrical And Electronic Engineering
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Platelet size has been shown to reflect platelet activity. We prospectively measured the mean platelet volume (MPV) in 47 patients undergoing single vessel angioplasty for symptomatic angina. The patients underwent repeat angiography 4-8... more
Platelet size has been shown to reflect platelet activity. We prospectively measured the mean platelet volume (MPV) in 47 patients undergoing single vessel angioplasty for symptomatic angina. The patients underwent repeat angiography 4-8 months later irrespective of symptomatic status. Restenosis was assessed quantitatively by hand held calliper measurements of the lesion and qualitatively by a return of angina, ST segment changes on an exercise test and visual analysis of the lesion severity by two experienced angiographers. Twenty-four patients developed recurrent angina during the follow-up period, the MPV in the group with chest pain was 8.54 +/- 0.60 fl compared to 8.1 +/- 0.69 fl in the asymptomatic group (P = 0.04). Twenty two patients had significant ST segment changes at exercise. In this group the MPV was 8.6 +/- 0.56 fl compared to 8.0 +/- 0.70 fl for the group with a negative test (P = 0.002). Similarly visually assessed angiographic stenosis showed a significant increase in the restenotic group (8.6 +/- 0.56 vs. 8.0 +/- 0.61 fl, P = 0.001). The relative odds for developing clinically defined restenosis were 10.2 times greater if the pre-procedural MPV lay in the upper compared to the lowest quartile. There was a positive correlation between MPV and change in minimal luminal diameter between post angioplasty and follow-up angiography, assessed quantitatively, r = +0.56, P = 0.016. There was no association between clinical or angiographic definitions of restenosis and haemoglobin, red cell count, mean corpuscular volume, white cell count or platelet count. Platelet size may influence the development of restenosis after successful coronary angioplasty.
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The incidence of cardiovascular disease is low in healthy premenopausal women and increases with age especially after the menopause; this difference has been attributed to the loss of endogenous estrogen. Atherosclerosis is a chronic... more
The incidence of cardiovascular disease is low in healthy premenopausal women and increases with age especially after the menopause; this difference has been attributed to the loss of endogenous estrogen. Atherosclerosis is a chronic inflammatory condition of the vascular wall that may result in an acute clinical event by inducing plaque rupture/erosion leading to thrombosis. A growing body of evidence suggests that the spectrum of the effects of estrogen on vascular pathophysiology is complex and may depend largely on the state of vascular pathology. In relatively healthy vessels, estrogen prevents the development and progression of atherosclerotic lesions, while in the presence of established atherosclerotic plaques, estrogen fails to inhibit the progression of atherosclerosis or may even trigger cardiovascular events. The mechanisms responsible for this are not yet fully elucidated. It is possible that postmenopausal estrogen/progestogen therapy may be beneficial in perimenopausal and early menopausal women prior to atherosclerotic plaque formation, but it may not prevent progression of atherosclerotic plaques and acute cardiovascular events in older women with cardiovascular risk factors or women with established atherosclerosis. Various formulations, doses and routes of hormone therapy administration as well as the genetic background of women should also be taken into account when considering the benefit-to-risk ratio of hormone therapy use.
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An air filled intraaortic balloon connected to an extravascular air chamber (compression chamber system-CCS) was used in 10 anesthetized dogs to increase its stroke volume (SV). Highest SV increases (up to over 200%) were observed at low... more
An air filled intraaortic balloon connected to an extravascular air chamber (compression chamber system-CCS) was used in 10 anesthetized dogs to increase its stroke volume (SV). Highest SV increases (up to over 200%) were observed at low SV states, with a high CCS volume and with high increases of the systolic pressure. The CCS pressure--systolic pressure relationship was a sigmoid-like curve. In conclusion, highest SV&#39;s may be achieved at low SV states, using CCS volumes about 400 ml and the highest CCS pressure that may cause a linear aortic pressure increase.