Ares Pasipoularides
Duke University School of Medicine, Surgery, Faculty Member
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests: Cardiology, Medicine, Humans, Internal Medicine, Blood Pressure, and 11 morePublic health systems and services research, American Heart Association, Aorta, Blood Flow Velocity, Aortic Valve, Postoperative Period, Aortic valve stenosis, Heart Valve Prosthesis Implantation, stenosis, Cardiovascular medicine and haematology, and Ventricular Function
Research Interests:
Research Interests: Neuroscience, Psychology, Epigenetics, Medicine, Gene expression, and 15 moreHumans, Animals, Mechanotransduction, Heart, Genome, Hydrodynamics, Diagnostic Imaging, Phenotype, Genotype, Myocardium, Translational Medical Research, Gene Expression Regulation, Biomechanical Phenomena, Diastole, and Ventricular Function
Research Interests:
Research Interests: Cardiology, Polymorphism, Medicine, Humans, Internal Medicine, and 9 moreLeft Ventricular Dysfunction, Public health systems and services research, American Heart Association, Large Scale, Hypertrophic Cardiomyopathy, Titin, Diastole, Diastolic dysfunction, and Cardiovascular medicine and haematology
Research Interests: Cardiology, Consciousness, Medicine, Dogs, Internal Medicine, and 15 moreHemodynamics, Ischemia, Animals, Relaxation, Animal Model, Clinical Sciences, Analysis of Variance, Heart Ventricles, Muscle Relaxation, Thoracic and cardiovascular surgery, Pressure Overload, Myocardial Ischemia, Diastole, systole, and Cardiovascular medicine and haematology
Research Interests:
Research Interests:
Research Interests: Cardiology, Medicine, Humans, Internal Medicine, Hemodynamics, and 12 moreFemale, Male, Feedback, Dilated cardiomyopathy, Middle Aged, Public health systems and services research, Cardiomyopathy, Coronary Circulation, Ejection Fraction, Blood Flow Velocity, Cardiovascular medicine and haematology, and ventricle
Research Interests: Chemistry, Cardiology, Medicine, Humans, Internal Medicine, and 15 moreHemodynamics, Blood Pressure, Acceleration, Outflow, Clinical Sciences, Cardiac Catheterization, Middle Aged, Adult, Circulation, Blood Flow Velocity, Pressure Gradient, Cardiovascular medicine and haematology, physical exertion, Ventricular Function, and supine position
Research Interests:
Research Interests:
Computer software for the IBM PC was developed to assess the contractile properties of the right and left ventricles simultaneously. Four indices of systolic function were computed from pressure and volume data. These four indices consist... more
Computer software for the IBM PC was developed to assess the contractile properties of the right and left ventricles simultaneously. Four indices of systolic function were computed from pressure and volume data. These four indices consist of the slopes and x intercepts of lines fitted to different aspects of the pressure-volume relationship. A shell-subtraction model was utilized to compute the
Research Interests:
Publisher Summary This chapter describes the pressure-diameter, stiffness-stress, and stiffness-radius relationships of the circumflex coronary artery in the conscious dog in the absence of the complicating influences of anesthesia and... more
Publisher Summary This chapter describes the pressure-diameter, stiffness-stress, and stiffness-radius relationships of the circumflex coronary artery in the conscious dog in the absence of the complicating influences of anesthesia and recent surgery, both in the control state and after smooth muscle activation with alpha-adrenergic stimulation. This was accomplished by direct and continuous measurements of aortic root pressure and of circumflex coronary artery diameter using a modified, ultrasound technique in chronically instrumented animals. The unique feature of this study of coronary arterial wall mechanics is that it was conducted in conscious animals without the complicating influences of general anesthesia and recent surgery in acute animal studies. Moreover, vascular dimensions were measured instantaneously and continuously using an ultrasonic dimension gauge. The ultrasonic dimension gauge used in this study was modified to provide measurements of small dimensions, such as those of the circumflex coronary artery of the dog, and to obtain calibrations in steps of 0.5 μ sec, that is, 0.75 mm.
Research Interests:
Research Interests:
Research Interests: Cardiology, Medicine, Elasticity, Humans, Internal Medicine, and 14 moreHemodynamics, Animals, Heart, Perfusion, Acute Myocardial Infarction, Myocardial Infarction, Public health systems and services research, Time Factors, Coronary Circulation, Coronary Artery Disease, Ejection Fraction, Biomechanical Phenomena, Acute Disease, and Cardiovascular medicine and haematology(Hemodynamics, Animals, Heart, Perfusion, Acute Myocardial Infarction, Myocardial Infarction, Public health systems and services research, Time Factors, Coronary Circulation, Coronary Artery Disease, Ejection Fraction, Biomechanical Phenomena, Acute Disease, and Cardiovascular medicine and haematology)
(Hemodynamics, Animals, Heart, Perfusion, Acute Myocardial Infarction, Myocardial Infarction, Public health systems and services research, Time Factors, Coronary Circulation, Coronary Artery Disease, Ejection Fraction, Biomechanical Phenomena, Acute Disease, and Cardiovascular medicine and haematology)
Research Interests:
Research Interests:
Research Interests:
Previous investigation of conventional isometric twitches of normothermic cat papillary muscle has shown that hypoxia prolongs relaxation, and this prolongation is actually accentuated during early reoxygenation. Our aim was to identify... more
Previous investigation of conventional isometric twitches of normothermic cat papillary muscle has shown that hypoxia prolongs relaxation, and this prolongation is actually accentuated during early reoxygenation. Our aim was to identify how hypoxia and reoxygenation affect the coupled processes of activation and inactivation that govern the time course of internally generated contractile tension (Ti). Activation and inactivation are modeled as first-order processes with rate constants ka and ki, respectively, and the overall isometric muscle as an underdamped second-order lag system driven by Ti. The analytical expression (To) for the externally recorded tension is dominated by two exponential terms incorporating ka and ki. Accurate least-squares fits of digitized twitches to To yielded estimates of ka and ki at 1- to 3-min intervals during control oxygenation, hypoxia, and early and late reoxygenation. Results follow. Compared with control, normothermic hypoxia prolonged activation...
Research Interests:
To investigate complementarity and competitiveness between the intrinsic and extrinsic components of the total left ventricular systolic load, hemodynamic data from 18 elderly subjects with severe aortic stenosis were analyzed before and... more
To investigate complementarity and competitiveness between the intrinsic and extrinsic components of the total left ventricular systolic load, hemodynamic data from 18 elderly subjects with severe aortic stenosis were analyzed before and after balloon dilation of the stenosed aortic valve. Multisensor micromanometric pressure measurements allowed calculation (simplified Bernoulli equation) of the ejection velocity and aortic input impedance spectra. Despite a 32% increase in the aortic valve area (from 0.56 +/- 0.04 to 0.74 +/- 0.05 cm2 [mean +/- SEM], p < 0.01), the peak left ventricular systolic pressure fell by only 12% (from 189 +/- 10 to 167 +/- 8 mm Hg, p < 0.01). This was accompanied by an increase in the impedance at the same cardiac output. In a subset of patients (n = 9) in whom the peak aortic systolic pressure rose after valvuloplasty (from 115 +/- 10 to 128 +/- 12 mm Hg, p < 0.01), a 40% increase in the aortic valve area was accompanied by a marked increase in ...
Research Interests: Mathematics, Cardiology, Medicine, Catheterization, Humans, and 15 moreInternal Medicine, Hemodynamics, Blood Pressure, Female, Male, Clinical Sciences, Aged, Circulation, Blood Flow Velocity, Aortic Valve, Postoperative Period, Aortic pressure, Aortic valve stenosis, Cardiovascular medicine and haematology, and Aortic Valvuloplasty
Analysis of a tapering, pulsatile flow field predicts that substantial subvalvular pressure gradients exist in patients with valvular aortic stenosis (AS) without invoking a second anatomic site of obstruction. Using a catheter with two... more
Analysis of a tapering, pulsatile flow field predicts that substantial subvalvular pressure gradients exist in patients with valvular aortic stenosis (AS) without invoking a second anatomic site of obstruction. Using a catheter with two laterally mounted micromanometers, we examined the left ventricle in 11 patients with AS, mean age 64 +/- 11 years (+/- SD); the mean valve area was 1.0 +/- 0.3 cm2. Simultaneous measurements were made in (1) the left ventricular (LV) chamber and the LV outflow tract (LVOT) and (2) the LVOT and ascending aorta (AO). No patient had anatomic evidence of a subvalvular obstruction, but large subvalvular gradients were present in all. The average peak LV-LVOT and LV-AO gradients were 41 +/- 17 mm Hg and 58 +/- 23 mm Hg, respectively. Flow velocity was electromagnetically derived in two patients. The LV-LVOT gradient was associated with an increased flow velocity in the LVOT. This study suggests that large subvalvular gradients are present in AS and help o...
Research Interests: Cardiology, Medicine, Electrocardiography, Humans, Internal Medicine, and 15 moreHemodynamics, Blood Pressure, Female, Male, Clinical Sciences, Aged, Cardiac Catheterization, Adult, Circulation, Hypertrophic Cardiomyopathy, Blood Flow Velocity, Aortic Valve, Aortic valve stenosis, Cardiovascular medicine and haematology, and ascending aorta
Research Interests:
Research Interests:
Functional imaging computational fluid dynamics simulations of right ventricular (RV) inflow fields were obtained by comprehensive software using individual animal-specific dynamic imaging data input from three-dimensional (3-D) real-time... more
Functional imaging computational fluid dynamics simulations of right ventricular (RV) inflow fields were obtained by comprehensive software using individual animal-specific dynamic imaging data input from three-dimensional (3-D) real-time echocardiography (RT3D) on a CRAY T-90 supercomputer. Chronically instrumented, lightly sedated awake dogs (n = 7) with normal wall motion (NWM) at control and normal or diastolic paradoxical septal motion (PSM) during RV volume overload were investigated. Up to the E-wave peak, instantaneous inflow streamlines extended from the tricuspid orifice to the RV endocardial surface in an expanding fanlike pattern. During the descending limb of the E-wave, large-scale (macroscopic or global) vortical motions ensued within the filling RV chamber. Both at control and during RV volume overload (with or without PSM), blood streams rolled up from regions near the walls toward the base. The extent and strength of the ring vortex surrounding the main stream were...
Research Interests:
Research Interests:
Functional imaging computational fluid dynamics simulations of right ventricular (RV) inflow fields were obtained by comprehensive software using individual animal-specific dynamic imaging data input from three-dimensional (3-D) real-time... more
Functional imaging computational fluid dynamics simulations of right ventricular (RV) inflow fields were obtained by comprehensive software using individual animal-specific dynamic imaging data input from three-dimensional (3-D) real-time echocardiography (RT3D) on a CRAY T-90 supercomputer. Chronically instrumented, lightly sedated awake dogs (n = 7) with normal wall motion (NWM) at control and normal or diastolic paradoxical septal motion (PSM) during RV volume overload were investigated. Up to the E-wave peak, instantaneous inflow streamlines extended from the tricuspid orifice to the RV endocardial surface in an expanding fanlike pattern. During the descending limb of the E-wave, large-scale (macroscopic or global) vortical motions ensued within the filling RV chamber. Both at control and during RV volume overload (with or without PSM), blood streams rolled up from regions near the walls toward the base. The extent and strength of the ring vortex surrounding the main stream were...
Research Interests: Physiology, Physics, Biomechanics, Medicine, Dogs, and 15 moreHemodynamics, Animals, Mechanoreceptors, Heart, American, Hydrodynamics, Medical Physiology, Blood Flow, Coronary Circulation, Blood Flow Velocity, Biomechanical Phenomena, tricuspid valve insufficiency, Diastole, Tourbillon, and endocardium
ABSTRACT We describe a novel functional imaging approach for quantitative analysis of right ventricular (RV) blood flow patterns in specific experimental animals (or humans) using real-time, three-dimensional (3-D) echocardiography... more
ABSTRACT We describe a novel functional imaging approach for quantitative analysis of right ventricular (RV) blood flow patterns in specific experimental animals (or humans) using real-time, three-dimensional (3-D) echocardiography (RT3D). The method is independent of the digital imaging modality used. It comprises three parts. First, a semiautomated segmentation aided by intraluminal contrast medium locates the RV endocardial surface. Second, a geometric scheme for dynamic RV chamber reconstruction applies a time interpolation procedure to the RT3D data to quantify wall geometry and motion at 400 Hz. A volumetric prism method validated the dynamic geometric reconstruction against simultaneous sonomicrometric canine measurements. Finally, the RV endocardial border motion information is used for mesh generation on a computational fluid dynamics solver to simulate development of the early RV diastolic inflow field. Boundary conditions (tessellated endocardial surface nodal velocities) for the solver are directly derived from the endocardial geometry and motion information. The new functional imaging approach may yield important kinematic information on the distribution of instantaneous velocities in the RV diastolic flow field of specific normal or diseased hearts.
Research Interests:
Research Interests:
Research Interests:
H ypertrophic cardiomyopathy (HCM) is a fascinating and polymorphic cardiac disease. Its impact on cardiac function retains intense clinical interest as it is one of the most common inherited cardiac diseases, affecting about 1 in 500... more
H ypertrophic cardiomyopathy (HCM) is a fascinating and polymorphic cardiac disease. Its impact on cardiac function retains intense clinical interest as it is one of the most common inherited cardiac diseases, affecting about 1 in 500 people. According to the prevalent view, HCM is a predominantly obstructive disease compromising systolic left ventricular (LV) ejection. Then again, impeded left ventricular orthograde emptying is not an invariable finding. Diastolic dysfunction associated with the abnormal hypertrophy patterns and their sequelae may also be responsible for impaired LV pumping performance. The diastolic peculiarities of LV dynamics in HCM were the focus of a companion survey. Additionally, the myocyte disorganization typifying HCM probably creates systolic contraction inefficiencies, and may be implicated in marked mechanical functional limitation in some HCM patients. As ejection flow characteristics became clinically measurable diagnostic features—with conventional ...
Research Interests:
Diastolic cardiac dysfunction as a component of heart failure is nowadays sufficiently recognized as to be a part of the coding for congestive heart failure in the International Classification of Diseases (ICD-10, codes I50.3033). This... more
Diastolic cardiac dysfunction as a component of heart failure is nowadays sufficiently recognized as to be a part of the coding for congestive heart failure in the International Classification of Diseases (ICD-10, codes I50.3033). This recognition of diastole by the World Health Organization has been accompanied by major strides in the appraisal of diastolic function,1-8 made possible by technology that encompasses multisensor cardiac catheterization,1,2,9-11 and invasive and noninvasive digital imaging modalities.1,12-22 It is now widely appreciated that enhancing diastolic filling has clinical merit and that the significance of diastolic dysfunction is far reaching.23,24 Nonetheless, the fact that in health and disease diastolic dynamics are dependent on a large number of factors and their interactions1-3,22,25 has complicated the evaluation of the multifactorial causes of the observed ventricular filling abnormalities. As our pathophysiologic understanding of heart failure has pr...
Research Interests:
Research Interests:
Genomics designates the coordinated investigation of a large number of genes in the context of a biological process or disease. It may be long before we attain comprehensive understanding of the genomics of common complex cardiovascular... more
Genomics designates the coordinated investigation of a large number of genes in the context of a biological process or disease. It may be long before we attain comprehensive understanding of the genomics of common complex cardiovascular diseases (CVDs) such as inherited cardiomyopathies, valvular diseases, primary arrhythmogenic conditions, congenital heart syndromes, hypercholesterolemia and atherosclerotic heart disease, hypertensive syndromes, and heart failure with preserved/reduced ejection fraction. Nonetheless, as genomics is evolving rapidly, it is constructive to survey now pertinent concepts and breakthroughs. Today, clinical multimodal electronic medical/health records (EMRs/EHRs) incorporating genomic information establish a continuously-learning, vast knowledge-network with seamless cycling between clinical application and research. It can inform insights into specific pathogenetic pathways, guide biomarker-assisted precise diagnoses and individualized treatments, and s...