Science.gov

Sample records for left ventricle finite-element

  1. Finite element stress analysis of the human left ventricle whose irregular shape is developed from single plane cineangiocardiogram

    NASA Technical Reports Server (NTRS)

    Ghista, D. N.; Hamid, M. S.

    1977-01-01

    The three-dimensional left ventricular chamber geometrical model is developed from single plane cineangiocardiogram. This left ventricular model is loaded by an internal pressure monitored by cardiac catheterization. The resulting stresses in the left ventricular model chamber's wall are determined by computerized finite element procedure. For the discretization of this left ventricular model structure, a 20-node, isoparametric finite element is employed. The analysis and formulation of the computerised procedure is presented in the paper, along with the detailed algorithms and computer programs. The procedure is applied to determine the stresses in a left ventricle at an instant, during systole. Next, a portion (represented by a finite element) of this left ventricular chamber is simulated as being infarcted by making its active-state modulus value equal to its passive-state value; the neighbouring elements are shown to relieve the 'infarcted' element of stress by themselves taking on more stress.

  2. Finite element analysis of left ventricle during cardiac cycles in viscoelasticity.

    PubMed

    Shen, Jing Jin; Xu, Feng Yu; Yang, Wen An

    2016-08-01

    To investigate the effect of myocardial viscoeslasticity on heart function, this paper presents a finite element model based on a hyper-viscoelastic model for the passive myocardium and Hill's three-element model for the active contraction. The hyper-viscoelastic model considers the myocardium microstructure, while the active model is phenomenologically based on the combination of Hill's equation for the steady tetanized contraction and the specific time-length-force property of the myocardial muscle. To validate the finite element model, the end-diastole strains and the end-systole strain predicted by the model are compared with the experimental values in the literature. It is found that the proposed model not only can estimate well the pumping function of the heart, but also predicts the transverse shear strains. The finite element model is also applied to analyze the influence of viscoelasticity on the residual stresses in the myocardium.

  3. Electromechanical feedback with reduced cellular connectivity alters electrical activity in an infarct injured left ventricle: a finite element model study

    PubMed Central

    Guccione, Julius M.; Ratcliffe, Mark B.; Sundnes, Joakim S.

    2012-01-01

    Myocardial infarction (MI) significantly alters the structure and function of the heart. As abnormal strain may drive heart failure and the generation of arrhythmias, we used computational methods to simulate a left ventricle with an MI over the course of a heartbeat to investigate strains and their potential implications to electrophysiology. We created a fully coupled finite element model of myocardial electromechanics consisting of a cellular physiological model, a bidomain electrical diffusion solver, and a nonlinear mechanics solver. A geometric mesh built from magnetic resonance imaging (MRI) measurements of an ovine left ventricle suffering from a surgically induced anteroapical infarct was used in the model, cycled through the cardiac loop of inflation, isovolumic contraction, ejection, and isovolumic relaxation. Stretch-activated currents were added as a mechanism of mechanoelectric feedback. Elevated fiber and cross fiber strains were observed in the area immediately adjacent to the aneurysm throughout the cardiac cycle, with a more dramatic increase in cross fiber strain than fiber strain. Stretch-activated channels decreased action potential (AP) dispersion in the remote myocardium while increasing it in the border zone. Decreases in electrical connectivity dramatically increased the changes in AP dispersion. The role of cross fiber strain in MI-injured hearts should be investigated more closely, since results indicate that these are more highly elevated than fiber strain in the border of the infarct. Decreases in connectivity may play an important role in the development of altered electrophysiology in the high-stretch regions of the heart. PMID:22058157

  4. Quasi-static image-based immersed boundary-finite element model of left ventricle under diastolic loading

    PubMed Central

    Gao, Hao; Wang, Huiming; Berry, Colin; Luo, Xiaoyu; Griffith, Boyce E

    2014-01-01

    Finite stress and strain analyses of the heart provide insight into the biomechanics of myocardial function and dysfunction. Herein, we describe progress toward dynamic patient-specific models of the left ventricle using an immersed boundary (IB) method with a finite element (FE) structural mechanics model. We use a structure-based hyperelastic strain-energy function to describe the passive mechanics of the ventricular myocardium, a realistic anatomical geometry reconstructed from clinical magnetic resonance images of a healthy human heart, and a rule-based fiber architecture. Numerical predictions of this IB/FE model are compared with results obtained by a commercial FE solver. We demonstrate that the IB/FE model yields results that are in good agreement with those of the conventional FE model under diastolic loading conditions, and the predictions of the LV model using either numerical method are shown to be consistent with previous computational and experimental data. These results are among the first to analyze the stress and strain predictions of IB models of ventricular mechanics, and they serve both to verify the IB/FE simulation framework and to validate the IB/FE model. Moreover, this work represents an important step toward using such models for fully dynamic fluid–structure interaction simulations of the heart. © 2014 The Authors. International Journal for Numerical Methods in Engineering published by John Wiley & Sons, Ltd. PMID:24799090

  5. Quasi-static image-based immersed boundary-finite element model of left ventricle under diastolic loading.

    PubMed

    Gao, Hao; Wang, Huiming; Berry, Colin; Luo, Xiaoyu; Griffith, Boyce E

    2014-11-01

    Finite stress and strain analyses of the heart provide insight into the biomechanics of myocardial function and dysfunction. Herein, we describe progress toward dynamic patient-specific models of the left ventricle using an immersed boundary (IB) method with a finite element (FE) structural mechanics model. We use a structure-based hyperelastic strain-energy function to describe the passive mechanics of the ventricular myocardium, a realistic anatomical geometry reconstructed from clinical magnetic resonance images of a healthy human heart, and a rule-based fiber architecture. Numerical predictions of this IB/FE model are compared with results obtained by a commercial FE solver. We demonstrate that the IB/FE model yields results that are in good agreement with those of the conventional FE model under diastolic loading conditions, and the predictions of the LV model using either numerical method are shown to be consistent with previous computational and experimental data. These results are among the first to analyze the stress and strain predictions of IB models of ventricular mechanics, and they serve both to verify the IB/FE simulation framework and to validate the IB/FE model. Moreover, this work represents an important step toward using such models for fully dynamic fluid-structure interaction simulations of the heart. © 2014 The Authors. International Journal for Numerical Methods in Engineering published by John Wiley & Sons, Ltd.

  6. Normal and pathological NCAT image and phantom data based on physiologically realistic left ventricle finite-element models.

    PubMed

    Veress, Alexander I; Segars, W Paul; Weiss, Jeffrey A; Tsui, Benjamin M W; Gullberg, Grant T

    2006-12-01

    The four-dimensional (4-D) NURBS-based cardiac-torso (NCAT) phantom, which provides a realistic model of the normal human anatomy and cardiac and respiratory motions, is used in medical imaging research to evaluate and improve imaging devices and techniques, especially dynamic cardiac applications. One limitation of the phantom is that it lacks the ability to accurately simulate altered functions of the heart that result from cardiac pathologies such as coronary artery disease (CAD). The goal of this work was to enhance the 4-D NCAT phantom by incorporating a physiologically based, finite-element (FE) mechanical model of the left ventricle (LV) to simulate both normal and abnormal cardiac motions. The geometry of the FE mechanical model was based on gated high-resolution X-ray multislice computed tomography (MSCT) data of a healthy male subject. The myocardial wall was represented as a transversely isotropic hyperelastic material, with the fiber angle varying from -90 degrees at the epicardial surface, through 0 degrees at the midwall, to 90 degrees at the endocardial surface. A time-varying elastance model was used to simulate fiber contraction, and physiological intraventricular systolic pressure-time curves were applied to simulate the cardiac motion over the entire cardiac cycle. To demonstrate the ability of the FE mechanical model to accurately simulate the normal cardiac motion as well as the abnormal motions indicative of CAD, a normal case and two pathologic cases were simulated and analyzed. In the first pathologic model, a subendocardial anterior ischemic region was defined. A second model was created with a transmural ischemic region defined in the same location. The FE-based deformations were incorporated into the 4-D NCAT cardiac model through the control points that define the cardiac structures in the phantom which were set to move according to the predictions of the mechanical model. A simulation study was performed using the FE-NCAT combination to

  7. Normal and Pathological NCAT Image and PhantomData Based onPhysiologically Realistic Left Ventricle Finite-Element Models

    SciTech Connect

    Veress, Alexander I.; Segars, W. Paul; Weiss, Jeffrey A.; Tsui,Benjamin M.W.; Gullberg, Grant T.

    2006-08-02

    The 4D NURBS-based Cardiac-Torso (NCAT) phantom, whichprovides a realistic model of the normal human anatomy and cardiac andrespiratory motions, is used in medical imaging research to evaluate andimprove imaging devices and techniques, especially dynamic cardiacapplications. One limitation of the phantom is that it lacks the abilityto accurately simulate altered functions of the heart that result fromcardiac pathologies such as coronary artery disease (CAD). The goal ofthis work was to enhance the 4D NCAT phantom by incorporating aphysiologically based, finite-element (FE) mechanical model of the leftventricle (LV) to simulate both normal and abnormal cardiac motions. Thegeometry of the FE mechanical model was based on gated high-resolutionx-ray multi-slice computed tomography (MSCT) data of a healthy malesubject. The myocardial wall was represented as transversely isotropichyperelastic material, with the fiber angle varying from -90 degrees atthe epicardial surface, through 0 degreesat the mid-wall, to 90 degreesat the endocardial surface. A time varying elastance model was used tosimulate fiber contraction, and physiological intraventricular systolicpressure-time curves were applied to simulate the cardiac motion over theentire cardiac cycle. To demonstrate the ability of the FE mechanicalmodel to accurately simulate the normal cardiac motion as well abnormalmotions indicative of CAD, a normal case and two pathologic cases weresimulated and analyzed. In the first pathologic model, a subendocardialanterior ischemic region was defined. A second model was created with atransmural ischemic region defined in the same location. The FE baseddeformations were incorporated into the 4D NCAT cardiac model through thecontrol points that define the cardiac structures in the phantom whichwere set to move according to the predictions of the mechanical model. Asimulation study was performed using the FE-NCAT combination toinvestigate how the differences in contractile function

  8. Dynamic finite-strain modelling of the human left ventricle in health and disease using an immersed boundary-finite element method

    PubMed Central

    Gao, Hao; Carrick, David; Berry, Colin; Griffith, Boyce E.; Luo, Xiaoyu

    2016-01-01

    Detailed models of the biomechanics of the heart are important both for developing improved interventions for patients with heart disease and also for patient risk stratification and treatment planning. For instance, stress distributions in the heart affect cardiac remodelling, but such distributions are not presently accessible in patients. Biomechanical models of the heart offer detailed three-dimensional deformation, stress and strain fields that can supplement conventional clinical data. In this work, we introduce dynamic computational models of the human left ventricle (LV) that are derived from clinical imaging data obtained from a healthy subject and from a patient with a myocardial infarction (MI). Both models incorporate a detailed invariant-based orthotropic description of the passive elasticity of the ventricular myocardium along with a detailed biophysical model of active tension generation in the ventricular muscle. These constitutive models are employed within a dynamic simulation framework that accounts for the inertia of the ventricular muscle and the blood that is based on an immersed boundary (IB) method with a finite element description of the structural mechanics. The geometry of the models is based on data obtained non-invasively by cardiac magnetic resonance (CMR). CMR imaging data are also used to estimate the parameters of the passive and active constitutive models, which are determined so that the simulated end-diastolic and end-systolic volumes agree with the corresponding volumes determined from the CMR imaging studies. Using these models, we simulate LV dynamics from enddiastole to end-systole. The results of our simulations are shown to be in good agreement with subject-specific CMR-derived strain measurements and also with earlier clinical studies on human LV strain distributions. PMID:27041786

  9. The direct incorporation of perfusion defect information to define ischemia and infarction in a finite element model of the left ventricle.

    PubMed

    Veress, Alexander I; Fung, George S K; Lee, Taek-Soo; Tsui, Benjamin M W; Kicska, Gregory A; Paul Segars, W; Gullberg, Grant T

    2015-05-01

    This paper describes the process in which complex lesion geometries (specified by computer generated perfusion defects) are incorporated in the description of nonlinear finite element (FE) mechanical models used for specifying the motion of the left ventricle (LV) in the 4D extended cardiac torso (XCAT) phantom to simulate gated cardiac image data. An image interrogation process was developed to define the elements in the LV mesh as ischemic or infarcted based upon the values of sampled intensity levels of the perfusion maps. The intensity values were determined for each of the interior integration points of every element of the FE mesh. The average element intensity levels were then determined. The elements with average intensity values below a user-controlled threshold were defined as ischemic or infarcted depending upon the model being defined. For the infarction model cases, the thresholding and interrogation process were repeated in order to define a border zone (BZ) surrounding the infarction. This methodology was evaluated using perfusion maps created by the perfusion cardiac-torso (PCAT) phantom an extension of the 4D XCAT phantom. The PCAT was used to create 3D perfusion maps representing 90% occlusions at four locations (left anterior descending (LAD) segments 6 and 9, left circumflex (LCX) segment 11, right coronary artery (RCA) segment 1) in the coronary tree. The volumes and shapes of the defects defined in the FE mechanical models were compared with perfusion maps produced by the PCAT. The models were incorporated into the XCAT phantom. The ischemia models had reduced stroke volume (SV) by 18-59 ml. and ejection fraction (EF) values by 14-50% points compared to the normal models. The infarction models, had less reductions in SV and EF, 17-54 ml. and 14-45% points, respectively. The volumes of the ischemic/infarcted regions of the models were nearly identical to those volumes obtained from the perfusion images and were highly correlated (R

  10. Bi-ventricular finite element model of right ventricle overload in the healthy rat heart.

    PubMed

    Masithulela, Fulufhelo

    2016-11-25

    The recognition of RV overpressure is critical to human life, as this may signify morbidity and mortality. Right ventricle (RV) dysfunction is understood to have an impact on the performance of the left ventricle (LV), but the mechanisms remain poorly understood. It is understood that ventricular compliance has the ability to affect cardiac performance. In this study, a bi-ventricular model of the rat heart was used in preference to other, single-ventricle models. Finite element analysis (FEA) of the bi-ventricular model provides important information on the function of the healthy heart. The passive myocardium was modelled as a nearly incompressible, hyperelastic, transversely isotropic material using finite element (FE) methods. Bi-ventricular geometries of healthy rat hearts reconstructed from magnetic resonance images were imported in Abaqus©. In simulating the normal passive filling of the rat heart, pressures of 4.8 kPa and 0.0098 kPa were applied to the inner walls of the LV and RV respectively. In addition, to simulate the overpressure of the RV, pressures of 2.4 kPa and 4.8 kPa were applied to the endocardial walls of the LV and RV respectively. As boundary conditions, the circumferential and longitudinal displacements at the base were set to zero. The radial displacements at the base were left free. The results show that the average circumferential stress at the mid-wall in the overloaded model increased from 2.8 kPa to 18.2 kPa. The average longitudinal stress increased from 1.5 kPa to 9.7 kPa. Additionally, in the radial direction, the average stress increased from 0.1 kPa to 0.6 kPa in the mid-wall. The average circumferential strain was found to be 0.138 and 0.100 on the endocardium of the over pressured and healthy model respectively. The average circumferential stress at the epicardium, mid-wall and endocardium in the case of a normal heart is 10 times lower than in the overloaded heart model. The finite analysis method is able to provide

  11. Computer Simulation of Blood Flow, Left Ventricular Wall Motion and Their Interrelationship by Fluid-Structure Interaction Finite Element Method

    NASA Astrophysics Data System (ADS)

    Watanabe, Hiroshi; Hisada, Toshiaki; Sugiura, Seiryo; Okada, Jun-Ichi; Fukunari, Hiroshi

    To simulate fluid-structure interaction involved in the contraction of a human left ventricle, a 3D finite element based simulation program incorporating the propagation of excitation and excitation-contraction coupling mechanisms was developed. An ALE finite element method with automatic mesh updating was formulated for large domain changes, and a strong coupling strategy was taken. Under the assumption that the inertias of both fluid and structure are negligible and fluid-structure interaction is restricted to the pressure on the interface, the fluid dynamics part was eliminated from the FSI program, and a static structural FEM code corresponding to the cardiac muscles was also developed. The simulations of the contraction of the left ventricle in normal excitation and arrhythmia demonstrated the capability of the proposed method. Also, the results obtained by the two methods are compared. These simulators can be powerful tools in the clinical practice of heart disease.

  12. Double inlet left ventricle

    MedlinePlus

    ... PA: Elsevier; 2016:chap 431. Kouchoukos NT, Blackstone EH, Hanley FL, Kirklin JK. Tricuspid atresia and single-ventricle physiology. In: Kouchoukos NT, Blackstone EH, Hanley FL, Kirklin JK, eds. Kirklin/Barratt-Boyes ...

  13. Left ventricular finite element model bounded by a systemic circulation model.

    PubMed

    Veress, A I; Raymond, G M; Gullberg, G T; Bassingthwaighte, J B

    2013-05-01

    A series of models were developed in which a circulatory system model was coupled to an existing series of finite element (FE) models of the left ventricle (LV). The circulatory models were used to provide realistic boundary conditions for the LV models. This was developed for the JSim analysis package and was composed of a systemic arterial, capillary, and venous system in a closed loop with a varying elastance LV and left atria to provide the driving pressures and flows matching those of the FE model. Three coupled models were developed, a normal LV under normotensive aortic loading (116/80 mm Hg), a mild hypertension (137/89 mm Hg) model, and a moderate hypertension model (165/100 mm Hg). The initial step in the modeling analysis was that the circulation was optimized to the end-diastolic pressure and volume values of the LV model. The cardiac FE models were then optimized to the systolic pressure/volume characteristics of the steady-state JSim circulatory model solution. Comparison of the stress predictions for the three models indicated that the mild hypertensive case produced a 21% increase in the average fiber stress levels, and the moderate hypertension case had a 36% increase in average stress. The circulatory work increased by 18% and 43% over that of the control for the mild and moderate hypertensive cases, respectively.

  14. Pseudoaneurysm of the left ventricle.

    PubMed Central

    Mackenzie, J W; Lemole, G M

    1994-01-01

    Pseudoaneurysm of the left ventricle most often occurs after transmural myocardial infarction but may also follow cardiac operations, trauma, inflammation, or infection. In contrast to patients with true ventricular aneurysm, those with false aneurysm most commonly die of hemorrhage. Review of the reported surgical experience and of our 14 cases confirms that standard chest radiographs with an abnormal cardiac silhouette and rapidly expanding size may alert the physician to this sometimes overlooked diagnosis. Noninvasive tests such as color-flow Doppler echocardiography, 2-dimensional echocardiography, cineangiographic computed tomography, and transesophageal echocardiography allow relatively easy recognition of these apparently rare lesions with increasing frequency. Cardiac catheterization, however, is usually still necessary for a clear picture of the location and anatomy of the aneurysm and the state of the coronary arteries. Finally, a new classification is proposed, consisting of true aneurysm, false aneurysm, pseudo-false aneurysm, and mixed aneurysm. Images PMID:7888805

  15. Time Components of the Left Ventricle.

    ERIC Educational Resources Information Center

    Franks, B. Don

    The purpose of this study was to examine the relationship of the time components of the left ventricle. Since one of the ways to investigate cardiac function is to analyze the time intervals between particular events of the cardiac cycle, various time intervals of systole and diastole of the left ventricle were measured from simultaneous…

  16. Sensitivity of left ventricular mechanics to myofiber architecture: A finite element study.

    PubMed

    Nikou, Amir; Gorman, Robert C; Wenk, Jonathan F

    2016-06-01

    The goal of this study was to investigate the sensitivity of computational models of the heart to their incorporated myofiber architecture during diastole. This architecture plays a critical role in the mechanical and electrical function of the heart and changes after myocardial tissue remodeling, which is associated with some of the most common heart diseases. In this study, a left ventricular finite element model of the porcine heart was created using magnetic resonance imaging, which represents the in vivo geometry. Various myofiber architectures were assigned to the finite element mesh, in the form of fiber and sheet angles. A structural-based material law was used to model the behavior of passive myocardium and its parameters were estimated using measured in vivo strains and cavity volume from magnetic resonance imaging. The final results showed noticeable sensitivity of the stress distribution to both the fiber and sheet angle distributions. This implies that a structural-based material law that takes into account the effect of both fiber and sheet angle distributions should be used. The results also show that although the simulation results improve using available data from histological studies of myocardial structure, the need for individualized myofiber architecture data is crucial.

  17. Regional left ventricular myocardial contractility and stress in a finite element model of posterobasal myocardial infarction.

    PubMed

    Wenk, Jonathan F; Sun, Kay; Zhang, Zhihong; Soleimani, Mehrdad; Ge, Liang; Saloner, David; Wallace, Arthur W; Ratcliffe, Mark B; Guccione, Julius M

    2011-04-01

    Recently, a noninvasive method for determining regional myocardial contractility, using an animal-specific finite element (FE) model-based optimization, was developed to study a sheep with anteroapical infarction (Sun et al., 2009, "A Computationally Efficient Formal Optimization of Regional Myocardial Contractility in a Sheep With Left Ventricular Aneurysm," ASME J. Biomech. Eng., 131(11), p. 111001). Using the methodology developed in the previous study (Sun et al., 2009, "A Computationally Efficient Formal Optimization of Regional Myocardial Contractility in a Sheep With Left Ventricular Aneurysm," ASME J. Biomech. Eng., 131(11), p. 111001), which incorporates tagged magnetic resonance images, three-dimensional myocardial strains, left ventricular (LV) volumes, and LV cardiac catheterization pressures, the regional myocardial contractility and stress distribution of a sheep with posterobasal infarction were investigated. Active material parameters in the noninfarcted border zone (BZ) myocardium adjacent to the infarct (T(max_B)), in the myocardium remote from the infarct (T(max_R)), and in the infarct (T(max_I)) were estimated by minimizing the errors between FE model-predicted and experimentally measured systolic strains and LV volumes using the previously developed optimization scheme. The optimized T(max_B) was found to be significantly depressed relative to T(max_R), while T(max_I) was found to be zero. The myofiber stress in the BZ was found to be elevated, relative to the remote region. This could cause further damage to the contracting myocytes, leading to heart failure.

  18. Finite Element Analysis of Stresses Developed in the Blood Sac of a Left Ventricular Assist Device

    PubMed Central

    Haut Donahue, T. L.; Dehlin, W.; Gillespie, J.; Weiss, W.J.; Rosenberg, G.

    2009-01-01

    The goal of this research is to develop a 3D finite element (FE) model of a left ventricular assist device (LVAD) to predict stresses in the blood sac. The hyperelastic stress-strain curves for the segmented poly(ether polyurethane urea) blood sac were determined in both tension and compression using a servo-hydraulic testing system at various strain rates. Over the range of strain rates studied, the sac was not strain rate sensitive, however the material response was different for tension versus compression. The experimental tension and compression properties were used in a FE model that consisted of the pusher plate, blood sac and pump case. A quasi-static analysis was used to allow for nonlinearities due to contact and material deformation. The 3D FE model showed that blood sac stresses are not adversely affected by the location of the inlet and outlet ports of the device and that over the systolic ejection phase of the simulation the prediction of blood sac stresses from the full 3D model and an axisymmetric model are the same. Minimizing stresses in the blood sac will increase the longevity of the blood sac in vivo. PMID:19131267

  19. Nonlinear dynamics of the left ventricle.

    PubMed

    Munteanu, Ligia; Chiroiu, Calin; Chiroiu, Veturia

    2002-05-01

    The cnoidal method is applied to solve the set of nonlinear dynamic equations of the left ventricle. By using the theta-function representation of the solutions and a genetic algorithm, the ventricular motion can be described as a linear superposition of cnoidal pulses and additional terms, which include nonlinear interactions among them.

  20. Feasibility of rapid and automated importation of 3D echocardiographic left ventricular (LV) geometry into a finite element (FEM) analysis model

    PubMed Central

    Verhey, Janko F; Nathan, Nadia S

    2004-01-01

    Background Finite element method (FEM) analysis for intraoperative modeling of the left ventricle (LV) is presently not possible. Since 3D structural data of the LV is now obtainable using standard transesophageal echocardiography (TEE) devices intraoperatively, the present study describes a method to transfer this data into a commercially available FEM analysis system: ABAQUS©. Methods In this prospective study TomTec LV Analysis TEE© Software was used for semi-automatic endocardial border detection, reconstruction, and volume-rendering of the clinical 3D echocardiographic data. A newly developed software program MVCP FemCoGen©, written in Delphi, reformats the TomTec file structures in five patients for use in ABAQUS and allows visualization of regional deformation of the LV. Results This study demonstrates that a fully automated importation of 3D TEE data into FEM modeling is feasible and can be efficiently accomplished in the operating room. Conclusion For complete intraoperative 3D LV finite element analysis, three input elements are necessary: 1. time-gaited, reality-based structural information, 2. continuous LV pressure and 3. instantaneous tissue elastance. The first of these elements is now available using the methods presented herein. PMID:15473901

  1. Left ventricle to left atrium shunt via a paravalvular abscess.

    PubMed

    Gasparovic, H; Smalcelj, A; Brida, M

    2009-10-01

    Intracardiac fistulas are rare complications of infective endocarditis that contribute to the complexity of surgical management, and impose an additional hemodynamic burden on the already challenged heart. We report on a case of successful surgical management of a paravalvular communication between the left ventricle and the left atrium via an abscess cavity. Georg Thieme Verlag KG Stuttgart. New York.

  2. Chronic obstructive pulmonary disease and left ventricle.

    PubMed

    Portillo, Karina; Abad-Capa, Jorge; Ruiz-Manzano, Juan

    2015-05-01

    Several studies have shown that the interaction between chronic obstructive pulmonary disease (COPD) and cardiovascular comorbidity is complex and bidirectional, since each of these diseases complicates the prognosis of the other. Recent advances in imaging technology have led to better characterization of cardiac chambers and allowed the relationship between certain cardiac function parameters and COPD clinical and functional variables to be explored. Although cardiac abnormalities in COPD have been mainly associated with the right ventricle, several studies have reported that the left ventricle may also be affected in this disease. A better understanding of the mechanisms involved and their clinical implications will establish diagnostic and therapeutic strategies for patients with both these conditions. Copyright © 2014 SEPAR. Published by Elsevier Espana. All rights reserved.

  3. A smoothed finite element method for analysis of anisotropic large deformation of passive rabbit ventricles in diastole.

    PubMed

    Jiang, Chen; Liu, Gui-Rong; Han, Xu; Zhang, Zhi-Qian; Zeng, Wei

    2015-01-01

    The smoothed FEM (S-FEM) is firstly extended to explore the behavior of 3D anisotropic large deformation of rabbit ventricles during the passive filling process in diastole. Because of the incompressibility of myocardium, a special method called selective face-based/node-based S-FEM using four-node tetrahedral elements (FS/NS-FEM-TET4) is adopted in order to avoid volumetric locking. To validate the proposed algorithms of FS/NS-FEM-TET4, the 3D Lame problem is implemented. The performance contest results show that our FS/NS-FEM-TET4 is accurate, volumetric locking-free and insensitive to mesh distortion than standard linear FEM because of absence of isoparametric mapping. Actually, the efficiency of FS/NS-FEM-TET4 is comparable with higher-order FEM, such as 10-node tetrahedral elements. The proposed method for Holzapfel myocardium hyperelastic strain energy is also validated by simple shear tests through the comparison outcomes reported in available references. Finally, the FS/NS-FEM-TET4 is applied in the example of the passive filling of MRI-based rabbit ventricles with fiber architecture derived from rule-based algorithm to demonstrate its efficiency. Hence, we conclude that FS/NS-FEM-TET4 is a promising alternative other than FEM in passive cardiac mechanics.

  4. Finite Element Modeling of Mitral Valve Repair

    PubMed Central

    Morgan, Ashley E.; Pantoja, Joe Luis; Weinsaft, Jonathan; Grossi, Eugene; Guccione, Julius M.; Ge, Liang; Ratcliffe, Mark

    2016-01-01

    The mitral valve is a complex structure regulating forward flow of blood between the left atrium and left ventricle (LV). Multiple disease processes can affect its proper function, and when these diseases cause severe mitral regurgitation (MR), optimal treatment is repair of the native valve. The mitral valve (MV) is a dynamic structure with multiple components that have complex interactions. Computational modeling through finite element (FE) analysis is a valuable tool to delineate the biomechanical properties of the mitral valve and understand its diseases and their repairs. In this review, we present an overview of relevant mitral valve diseases, and describe the evolution of FE models of surgical valve repair techniques. PMID:26632260

  5. Hemodynamic forces in a model left ventricle

    NASA Astrophysics Data System (ADS)

    Domenichini, Federico; Pedrizzetti, Gianni

    2016-12-01

    Intraventricular pressure gradients were clinically demonstrated to represent one useful indicator of the left ventricle (LV) function during the development of heart failure. We analyze the fluid dynamics inside a model LV to improve the understanding of the development of hemodynamic forces (i.e., mean pressure gradient) in normal conditions and their modification in the presence of alterations of LV tissue motion. To this aim, the problem is solved numerically and the global force exchanged between blood flow and LV boundaries is computed by volume integration. We also introduce a simplified analytical model, based on global conservation laws, to estimate hemodynamic forces from the knowledge of LV tissue information commonly available in cardiac imaging. Numerical results show that the normal intraventricular gradients feature a deep brief suction at early diastolic filling and a persistent thrust during systolic ejection. In presence of abnormalities of the wall motion, the loss of time synchrony is more relevant than the loss of spatial uniformity in modifying the normal pressure gradient spatiotemporal pattern. The main findings are reproduced in the integral model, which represents a possible easy approach for integrating fluid dynamics evaluations in the clinical examination.

  6. An Inverse Finite Element Method for Determining the Tissue Compressibility of Human Left Ventricular Wall during the Cardiac Cycle

    PubMed Central

    Hassaballah, Abdallah I.; Hassan, Mohsen A.; Mardi, Azizi N.; Hamdi, Mohd

    2013-01-01

    The determination of the myocardium’s tissue properties is important in constructing functional finite element (FE) models of the human heart. To obtain accurate properties especially for functional modeling of a heart, tissue properties have to be determined in vivo. At present, there are only few in vivo methods that can be applied to characterize the internal myocardium tissue mechanics. This work introduced and evaluated an FE inverse method to determine the myocardial tissue compressibility. Specifically, it combined an inverse FE method with the experimentally-measured left ventricular (LV) internal cavity pressure and volume versus time curves. Results indicated that the FE inverse method showed good correlation between LV repolarization and the variations in the myocardium tissue bulk modulus K (K = 1/compressibility), as well as provided an ability to describe in vivo human myocardium material behavior. The myocardium bulk modulus can be effectively used as a diagnostic tool of the heart ejection fraction. The model developed is proved to be robust and efficient. It offers a new perspective and means to the study of living-myocardium tissue properties, as it shows the variation of the bulk modulus throughout the cardiac cycle. PMID:24367544

  7. An inverse finite element method for determining the tissue compressibility of human left ventricular wall during the cardiac cycle.

    PubMed

    Hassaballah, Abdallah I; Hassan, Mohsen A; Mardi, Azizi N; Hamdi, Mohd

    2013-01-01

    The determination of the myocardium's tissue properties is important in constructing functional finite element (FE) models of the human heart. To obtain accurate properties especially for functional modeling of a heart, tissue properties have to be determined in vivo. At present, there are only few in vivo methods that can be applied to characterize the internal myocardium tissue mechanics. This work introduced and evaluated an FE inverse method to determine the myocardial tissue compressibility. Specifically, it combined an inverse FE method with the experimentally-measured left ventricular (LV) internal cavity pressure and volume versus time curves. Results indicated that the FE inverse method showed good correlation between LV repolarization and the variations in the myocardium tissue bulk modulus K (K = 1/compressibility), as well as provided an ability to describe in vivo human myocardium material behavior. The myocardium bulk modulus can be effectively used as a diagnostic tool of the heart ejection fraction. The model developed is proved to be robust and efficient. It offers a new perspective and means to the study of living-myocardium tissue properties, as it shows the variation of the bulk modulus throughout the cardiac cycle.

  8. Study of cardiovascular function using a coupled left ventricle and systemic circulation model.

    PubMed

    Chen, W W; Gao, H; Luo, X Y; Hill, N A

    2016-08-16

    To gain insight into cardio-arterial interactions, a coupled left ventricle-systemic artery (LV-SA) model is developed that incorporates a three-dimensional finite-strain left ventricle (LV), and a physiologically-based one-dimensional model for the systemic arteries (SA). The coupling of the LV model and the SA model is achieved by matching the pressure and the flow rate at the aortic root, i.e. the SA model feeds back the pressure as a boundary condition to the LV model, and the aortic flow rate from the LV model is used as the input for the SA model. The governing equations of the coupled system are solved using a combined immersed-boundary finite-element (IB/FE) method and a Lax-Wendroff scheme. A baseline case using physiological measurements of healthy subjects, and four exemplar cases based on different physiological and pathological scenarios are studied using the LV-SA model. The results of the baseline case agree well with published experimental data. The four exemplar cases predict varied pathological responses of the cardiovascular system, which are also supported by clinical observations. The new model can be used to gain insight into cardio-arterial interactions across a range of clinical applications. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  9. Patient-specific simulation of a trileaflet aortic heart valve in a realistic left ventricle and aorta

    NASA Astrophysics Data System (ADS)

    Gilmanov, Anvar; Le, Trung; Stolarski, Henryk; Sotiropoulos, Fotis

    2013-11-01

    We develop a patient-specific model of the left ventricle consisting of: (1) magnetic-resonance images (MRI) data for wall geometry and kinematics reconstruction of the left ventricle during one cardiac cycle and (2) an elastic trileaflet aortic heart valve implanted in (3) a realistic aorta interacting with blood flow driven by the pulsating left ventricle. Blood flow is simulated via a new fluid-structure interaction (FSI) method, which couples the sharp-interface CURVIB [L. Ge, F. Sotiropoulos, JCP, (2007)] for handling complex moving boundaries with a new, rotation-free finite-element (FE) formulation for simulating large tissue deformations [H. Stolarski, A. Gilmanov, F. Sotiropoulos, IJNME, (2013)] The new FE shell formulation has been extensively tested and validated for a range of relevant problems showing good agreements. Validation of the coupled FSI-FE-CURVIB model is carried out for a thin plate undergoing flow-induced vibrations in the wake of a square cylinder and the computed results are in good agreement with published data. The new approach has been applied to simulate dynamic interaction of a trileaflet aortic heart valve with pulsating blood flow at physiological conditions and realistic artery and left ventricle geometry.

  10. [Endomyocardial fibrosis with massive calcification of the left ventricle].

    PubMed

    Trigo, Joana; Camacho, Ana; Gago, Paula; Candeias, Rui; Santos, Walter; Marques, Nuno; Matos, Pedro; Brandão, Victor; Gomes, Veloso

    2010-03-01

    Endomyocardial fibrosis is a rare disease, endemic in tropical countries. It is characterized by fibrosis of the endocardium that can extend to myocardium. Important calcification of the endocardium is rare with only a few cases reported in the literature. We report a case of endomyocardial fibrosis in a european caucasian patient, associated with massive calcification of left ventricle.

  11. The influence of inflow cannula malposition and left ventricle size on intraventricular thrombosis risk for Left Ventricle Assist Device

    NASA Astrophysics Data System (ADS)

    Chivukula, V. Keshav; McGah, Patrick; Prisco, Anthony; Beckman, Jennifer; Mokadam, Nanush; Mahr, Claudius; Aliseda, Alberto

    2016-11-01

    Patients with left ventricular assist devices (LVAD) have high incidence of thrombosis and stroke. Patient-specific left ventricle 3D models were created with different LVAD inflow cannula angles with the ventricle axis (in increments of +/-7o). Left ventricle sizes ranging from 4 - 7 . 5cm in diameter were studied. The aim is optimizing inflow cannula selection and alignment in LVAD patients by understanding the roles that misalignment of the cannula and ventricle size variability play in platelet activation, residence time and agglomeration. Unsteady CFD simulations with patient-specific boundary conditions were performed, and particle tracking was conducted for 10 cardiac cycles to compute the residence time and shear stress histories of platelets for different configurations. Eulerian and Lagrangian metrics, as well as a newly-developed thrombogenic potential score were calculated and used to assess the thrombogenic risk associated with the inflow cannula. Results indicate that inflow cannula misalignment can significantly increase the risk of thrombosis. Cannula sizing without ventricle size consideration affects thrombogenecity for patients outside the normal range (5-6 cm). A methodology is outlined for minimization of thrombotic potential in LVAD implantation strategies

  12. Left Ventricle Diverticulum with Partial Cantrell's Syndrome

    PubMed Central

    El Kouache, Mustapha; Labib, S.; El Madi, A.; Babakhoya, A.; Atmani, S.; Abouabdilah, Y.; Harandou, M.

    2012-01-01

    Cantrell syndrome is a very rare congenital disease associating five features: a midline, upper abdominal wall disorder, lower sternal abnormality, anterior diaphragmatic defect, diaphragmatic pericardial abnormality, and congenital abnormalities of the heart. In this paper, we report a case of partial Cantrell's syndrome with left ventricular diverticulum, triatrial situs solitus, ventricular septal defect, dextrorotation of the heart, an anterior pericardial diaphragmatic defect, and a midline supraumbilical abdominal wall defect with umbilical hernia. The 5-month-old patient underwent a successful cardiac surgical procedure. A PTFE membrane was placed on the apex of the heart to facilitate reopening of the patient's chest. Postoperative course was uneventful. The patient was discharged with good clinical condition and with a normal cardiac function. PMID:24826242

  13. Application of NASTRAN for stress analysis of left ventricle of the heart

    NASA Technical Reports Server (NTRS)

    Pao, Y. C.; Ritman, E. L.; Wang, H. C.

    1975-01-01

    Knowing the stress and strain distributions in the left ventricular wall of the heart is a prerequisite for the determination of the muscle elasticity and contractility in the process of assessing the functional status of the heart. NASTRAN was applied for the calculation of these stresses and strains and to help in verifying the results obtained by the computer program FEAMPS which was specifically designed for the plane-strain finite-element analysis of the left ventricular cross sections. Adopted for the analysis are the true shape and dimensions of the cross sections reconstructed from multiplanar X-ray views of a left ventricle which was surgically isolated from a dog's heart but metabolically supported to sustain its beating. A preprocessor was prepared to accommodate both FEAMPS and NASTRAN, and it has also facilitated the application of both the triangular element and isoparameteric quadrilateral element versions of NASTRAN. The stresses in several crucial regions of the left ventricular wall calculated by these two independently developed computer programs are found to be in good agreement. Such confirmation of the results is essential in the development of a method which assesses the heart performance.

  14. Is the human left ventricle partially a fractal pump?

    NASA Astrophysics Data System (ADS)

    Moore, Brandon; Dasi, Lakshmi

    2011-11-01

    Ventricular systolic and diastolic dysfunctions represent a large portion of healthcare problems in the United States. Many of these problems are caused and/or characterized by their altered fluid-structure mechanics. The structure of the left ventricle in particular is complex with time dependent multi-scale geometric complexity. At relatively small scales, one facet that is still not well understood is the role of trabeculae in the pumping function of the left ventricle. We utilize fractal geometry tools to help characterize the complexity of the inner surface of the left ventricle at different times during the cardiac cycle. A high-resolution three dimensional model of the time dependent ventricular geometry was constructed from computed tomography (CT) images in a human. The scale dependent fractal dimension of the ventricle was determined using the box-counting algorithm over the cardiac cycle. It is shown that the trabeculae may indeed play an integral role in the biomechanics of pumping by regulating the mechanical leverage available to the cardiac muscle fibers.

  15. A strategic approach for cardiac MR left ventricle segmentation.

    PubMed

    Dakua, Sarada Prasad; Sahambi, J S

    2010-09-01

    Quantitative evaluation of cardiac function from cardiac magnetic resonance (CMR) images requires the identification of the myocardial walls. This generally requires the clinician to view the image and interactively trace the contours. Especially, detection of myocardial walls of left ventricle is a difficult task in CMR images that are obtained from subjects having serious diseases. An approach to automated outlining the left ventricular contour is proposed. In order to segment the left ventricle, in this paper, a combination of two approaches is suggested. Difference of Gaussian weighting function (DoG) is newly introduced in random walk approach for blood pool (inner contour) extraction. The myocardial wall (outer contour) is segmented out by a modified active contour method that takes blood pool boundary as the initial contour. Promising experimental results in CMR images demonstrate the potentials of our approach.

  16. Coronary fistula to the left ventricle: assessed by computed tomography.

    PubMed

    Mendonça, Roberto Moreno; Bandeira, Rodrigo Lima; Fonseca, Fredson J S; Macedo Filho, Robson

    2011-10-01

    Coronary artery fistulas are rare and are most often diagnosed by echocardiography or by cine-angiocardiography. However, the computed tomography angiography (CTA) of coronary arteries has been gaining ground. The incidence of this disease is very low, with a more frequent occurrence of fistulas originating in the right coronary artery. There is a higher incidence of coronary artery fistulas to right heart chambers, with coronary artery fistulas to the left ventricle (LV) being rare. Treatment can be surgical or percutaneous. This report describes a case of coronary fistula to left ventricle diagnosed by CT angiography of coronary arteries in a hypertensive and asymptomatic 46-year-old male, who was tested positive for ischemia in an exercise test. The CT angiography ruled out coronary obstructive disease, but it revealed a coronary fistula to the left ventricular cavity.

  17. Finite Element Analysis on the Relationship between Left Ventricular Pump Function and Fiber Structure within the Wall

    NASA Astrophysics Data System (ADS)

    Watanabe, Hiroshi; Sugiura, Seiryo; Hisada, Toshiaki

    In this study, a 3D finite element based simulation program incorporating the propagation of excitation and excitation-contraction coupling mechanisms developed by us was modified to reproduce the more realistic ventricular wall structure. FE model of LV consists of six layers of muscle bundles and the fiber direction of the inner-most layer was longitudinal. Although the detailed modeling did not influence the global pump function of the LV appreciably, we could successfully identify the functional significance of longitudinal fibers as pointed out by clinical observations. Furthermore, we also changed the heart structure drastically to elucidate the functional significance of the fiber structure. The results suggest that the double-helical structure the heart has developed through the evolutionary process can be an optimal design for a blood pump.

  18. Double-outlet right ventricle with an intact interventricular septum and concurrent hypoplastic left ventricle in a calf.

    PubMed

    Newhard, D K; Jung, S W; Winter, R L; Kuca, T; Bayne, J; Passler, T

    2017-01-19

    A 3-day-old Hereford heifer calf presented for evaluation of lethargy and dyspnea, with persistent hypoxia despite supplemental oxygen therapy. A grade III/VI right apical systolic murmur was noted during cardiac auscultation. Echocardiography revealed a double-outlet right ventricle with an intact interventricular septum and concurrent hypoplastic left ventricle and tricuspid valve dysplasia. Post-mortem examination revealed additional congenital anomalies of ductus arteriosus, patent foramen ovale, and persistent left cranial vena cava. This report illustrates the use of echocardiographic images to diagnose a double-outlet right ventricle with an intact interventricular septum and a hypoplastic left ventricle in a calf.

  19. Ischemic contracture of the left ventricle. Production and prevention.

    PubMed

    MacGregor, D C; Wilson, G J; Tanaka, S; Holness, D E; Lixfeld, W; Silver, M D; Rubis, L J; Goldstein, W; Gunstensen, J; Bigelow, W G

    1975-12-01

    Ischemic contracture of the left ventricle ("stone heart") is a recognized complication of prolonged periods of interruption of the coronary circulation during open-heart surgery. We have examined the effects of moderate hypothermia (28 degrees C.) and preoperative beta-adrenergic blockade (propranolol, 0.5 mg. per kilogram; 1.0 mg. per kilogram) on contracture development during ischemic arrest of the heart. Four groups of 8 dogs each were placed on total cardiopulmonary bypass, and ischemic arrest of the heart was produced by cross-clamping the ascending aorta and venting the left ventricle. Intramyocardial carbon dioxide tension was continuously monitored by mass spectrometry. When anaerobic energy production ceased, as indicated by a final plateau in the intramyocardial carbon dioxide accumulation curve, the ischemic arrest was terminated and the contractile state of the heart observed. These results are given in the text. We conclude that beta-adrenergic blockade delays, but does not prevent, the onset of ischemic contracture of the left ventricle under normothermic conditions. Moderate hypothermia appears to prevent this complication completely.

  20. A coupled mitral valve-left ventricle model with fluid-structure interaction.

    PubMed

    Gao, Hao; Feng, Liuyang; Qi, Nan; Berry, Colin; Griffith, Boyce E; Luo, Xiaoyu

    2017-09-01

    Understanding the interaction between the valves and walls of the heart is important in assessing and subsequently treating heart dysfunction. This study presents an integrated model of the mitral valve (MV) coupled to the left ventricle (LV), with the geometry derived from in vivo clinical magnetic resonance images. Numerical simulations using this coupled MV-LV model are developed using an immersed boundary/finite element method. The model incorporates detailed valvular features, left ventricular contraction, nonlinear soft tissue mechanics, and fluid-mediated interactions between the MV and LV wall. We use the model to simulate cardiac function from diastole to systole. Numerically predicted LV pump function agrees well with in vivo data of the imaged healthy volunteer, including the peak aortic flow rate, the systolic ejection duration, and the LV ejection fraction. In vivo MV dynamics are qualitatively captured. We further demonstrate that the diastolic filling pressure increases significantly with impaired myocardial active relaxation to maintain a normal cardiac output. This is consistent with clinical observations. The coupled model has the potential to advance our fundamental knowledge of mechanisms underlying MV-LV interaction, and help in risk stratification and optimisation of therapies for heart diseases. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  1. Measurement of Strain in the Left Ventricle during Diastole withcine-MRI and Deformable Image Registration

    SciTech Connect

    Veress, Alexander I.; Gullberg, Grant T.; Weiss, Jeffrey A.

    2005-07-20

    The assessment of regional heart wall motion (local strain) can localize ischemic myocardial disease, evaluate myocardial viability and identify impaired cardiac function due to hypertrophic or dilated cardiomyopathies. The objectives of this research were to develop and validate a technique known as Hyperelastic Warping for the measurement of local strains in the left ventricle from clinical cine-MRI image datasets. The technique uses differences in image intensities between template (reference) and target (loaded) image datasets to generate a body force that deforms a finite element (FE) representation of the template so that it registers with the target image. To validate the technique, MRI image datasets representing two deformation states of a left ventricle were created such that the deformation map between the states represented in the images was known. A beginning diastoliccine-MRI image dataset from a normal human subject was defined as the template. A second image dataset (target) was created by mapping the template image using the deformation results obtained from a forward FE model of diastolic filling. Fiber stretch and strain predictions from Hyperelastic Warping showed good agreement with those of the forward solution. The technique had low sensitivity to changes in material parameters, with the exception of changes in bulk modulus of the material. The use of an isotropic hyperelastic constitutive model in the Warping analyses degraded the predictions of fiber stretch. Results were unaffected by simulated noise down to an SNR of 4.0. This study demonstrates that Warping in conjunction with cine-MRI imaging can be used to determine local ventricular strains during diastole.

  2. A structure-function analysis of the left ventricle

    PubMed Central

    Meyer, Leith C. R.; Fuller, Andrea; Haw, Anna; Mitchell, Duncan; Farrell, Anthony P.; Costello, Mary-Ann; Izwan, Adian; Badenhorst, Margaret; Maloney, Shane K.

    2016-01-01

    This study presents a structure-function analysis of the mammalian left ventricle and examines the performance of the cardiac capillary network, mitochondria, and myofibrils at rest and during simulated heavy exercise. Left ventricular external mechanical work rate was calculated from cardiac output and systemic mean arterial blood pressure in resting sheep (Ovis aries; n = 4) and goats (Capra hircus; n = 4) under mild sedation, followed by perfusion-fixation of the left ventricle and quantification of the cardiac capillary-tissue geometry and cardiomyocyte ultrastructure. The investigation was then extended to heavy exercise by increasing cardiac work according to published hemodynamics of sheep and goats performing sustained treadmill exercise. Left ventricular work rate averaged 0.017 W/cm3 of tissue at rest and was estimated to increase to ∼0.060 W/cm3 during heavy exercise. According to an oxygen transport model we applied to the left ventricular tissue, we predicted that oxygen consumption increases from 195 nmol O2·s−1·cm−3 of tissue at rest to ∼600 nmol O2·s−1·cm−3 during heavy exercise, which is within 90% of the oxygen demand rate and consistent with work remaining predominantly aerobic. Mitochondria represent 21-22% of cardiomyocyte volume and consume oxygen at a rate of 1,150 nmol O2·s−1·cm−3 of mitochondria at rest and ∼3,600 nmol O2·s−1·cm−3 during heavy exercise, which is within 80% of maximum in vitro rates and consistent with mitochondria operating near their functional limits. Myofibrils represent 65–66% of cardiomyocyte volume, and according to a Laplacian model of the left ventricular chamber, generate peak fiber tensions in the range of 50 to 70 kPa at rest and during heavy exercise, which is less than maximum tension of isolated cardiac tissue (120–140 kPa) and is explained by an apparent reserve capacity for tension development built into the left ventricle. PMID:27586835

  3. Vortex formation and instability in the left ventricle

    NASA Astrophysics Data System (ADS)

    Le, Trung Bao; Sotiropoulos, Fotis; Coffey, Dane; Keefe, Daniel

    2012-09-01

    We study the formation of the mitral vortex ring during early diastolic filling in a patient-specific left ventricle (LV) using direct numerical simulation. The geometry of the left ventricle is reconstructed from Magnetic Resonance Imaging (MRI) data of a healthy human subject. The left ventricular kinematics is modeled via a cell-based activation methodology, which is inspired by cardiac electro-physiology and yields physiologic LV wall motion. In the fluid dynamics videos, we describe in detail the three-dimensional structure of the mitral vortex ring, which is formed during early diastolic filling. The ring starts to deform as it propagates toward the apex of the heart and becomes inclined. The trailing secondary vortex tubes are formed as the result of interaction between the vortex ring and the LV wall. These vortex tubes wrap around the circumference and begin to interact with and destabilize the mitral vortex ring. At the end of diastole, the vortex ring impinges on the LV wall and the large-scale intraventricular flow rotates in clockwise direction. We show for the first time that the mitral vortex ring evolution is dominated by a number of vortex-vortex and vortex-wall interactions, including lateral straining and deformation of vortex ring, the interaction of two vortex tubes with unequal strengths, helicity polarization of vortex tubes and twisting instabilities of the vortex cores.

  4. Automatic functional analysis of left ventricle in cardiac cine MRI.

    PubMed

    Lu, Ying-Li; Connelly, Kim A; Dick, Alexander J; Wright, Graham A; Radau, Perry E

    2013-08-01

    A fully automated left ventricle segmentation method for the functional analysis of cine short axis (SAX) magnetic resonance (MR) images was developed, and its performance evaluated with 133 studies of subjects with diverse pathology: ischemic heart failure (n=34), non-ischemic heart failure (n=30), hypertrophy (n=32), and healthy (n=37). The proposed automatic method locates the left ventricle (LV), then for each image detects the contours of the endocardium, epicardium, papillary muscles and trabeculations. Manually and automatically determined contours and functional parameters were compared quantitatively. There was no significant difference between automatically and manually determined end systolic volume (ESV), end diastolic volume (EDV), ejection fraction (EF) and left ventricular mass (LVM) for each of the four groups (paired sample t-test, α=0.05). The automatically determined functional parameters showed high correlations with those derived from manual contours, and the Bland-Altman analysis biases were small (1.51 mL, 1.69 mL, -0.02%, -0.66 g for ESV, EDV, EF and LVM, respectively). The proposed technique automatically and rapidly detects endocardial, epicardial, papillary muscles' and trabeculations' contours providing accurate and reproducible quantitative MRI parameters, including LV mass and EF.

  5. Automatic functional analysis of left ventricle in cardiac cine MRI

    PubMed Central

    Lu, Ying-Li; Connelly, Kim A.; Dick, Alexander J.; Wright, Graham A.

    2013-01-01

    Rationale and objectives A fully automated left ventricle segmentation method for the functional analysis of cine short axis (SAX) magnetic resonance (MR) images was developed, and its performance evaluated with 133 studies of subjects with diverse pathology: ischemic heart failure (n=34), non-ischemic heart failure (n=30), hypertrophy (n=32), and healthy (n=37). Materials and methods The proposed automatic method locates the left ventricle (LV), then for each image detects the contours of the endocardium, epicardium, papillary muscles and trabeculations. Manually and automatically determined contours and functional parameters were compared quantitatively. Results There was no significant difference between automatically and manually determined end systolic volume (ESV), end diastolic volume (EDV), ejection fraction (EF) and left ventricular mass (LVM) for each of the four groups (paired sample t-test, α=0.05). The automatically determined functional parameters showed high correlations with those derived from manual contours, and the Bland-Altman analysis biases were small (1.51 mL, 1.69 mL, –0.02%, –0.66 g for ESV, EDV, EF and LVM, respectively). Conclusions The proposed technique automatically and rapidly detects endocardial, epicardial, papillary muscles’ and trabeculations’ contours providing accurate and reproducible quantitative MRI parameters, including LV mass and EF. PMID:24040616

  6. Endovascular Treatment of Two Pseudoaneurysms Originating From the Left Ventricle

    SciTech Connect

    Cwikiel, Wojciech Keussen, Inger; Gustafsson, Ronny; Mokhtari, Arash

    2013-12-15

    A 67-year-old woman resented with an acute type A aortic dissection, which was treated surgically with aortic valve replacement as a composite graft with reimplantation of the coronary arteries. At the end of surgery, a left-ventricular venting catheter was placed through the apex and closed with a buffered suture. Consecutive computed tomography (CT) examinations verified a growing apex pseudoaneurysm. Communication between the ventricle and the pseudoaneurysm was successfully closed with an Amplatz septal plug by the transfemoral route. Follow-up CT showed an additional pseudoaneurysm, which also was successfully closed using the same method.

  7. [Akinetic zones of the left ventricle in aortic insufficiency. Treatment].

    PubMed

    Actis Dato, A; Panero, G B; De Michelis, M; Borio-Alluto, L

    1975-12-05

    22 cases of aortic valvular insufficiency treated by prosthesis and in which the acinetic areas of the left ventricle were eliminated at the same time are reported. Only one postoperative death (ventricular fibrillation) was encountered; one after 1 year (emboly as a result of endocarditis) and one as a result of an unknown cause. Emphasis is laid upon the frequency of this associated complication, its seriously negative incidence on ventricular haemodynamics, the need for surgical treatment, and its favourable immediate and long-term results.

  8. Three-dimensional diastolic blood flow in the left ventricle.

    PubMed

    Khalafvand, Seyed Saeid; Ng, Eddie Yin-Kwee; Zhong, Liang; Hung, Tin-Kan

    2017-01-04

    Three-dimensional blood flow in a human left ventricle is studied via a computational analysis with magnetic resonance imaging of the cardiac motion. Formation, growth and decay of vortices during the myocardial dilation are analyzed with flow patterns on various diametric planes. They are dominated by momentum transfer during flow acceleration and deceleration through the mitral orifice. The posterior and anterior vortices form an asymmetric annular vortex at the mitral orifice, providing a smooth transition for the rapid inflow to the ventricle. The development of core vortex accommodates momentum for deceleration and for acceleration at end diastolic atrial contraction. The rate of energy dissipation and that of work done by viscous stresses are small; they are approximately balanced with each other. The kinetic energy flux and the rate of work done by pressure delivered to blood from ventricular dilation is well balanced by the total energy influx at the mitral orifice and the rate change of kinetic energy in the ventricle. Published by Elsevier Ltd.

  9. [Gigantic coronary aneurysm arisen from coronary fistula between the left circumflex artery and the left ventricle].

    PubMed

    Uchida, T; Andou, H; Yasutsune, T; Iwai, T; Fukumura, F; Tanaka, J

    2008-12-01

    A 71-year-old male was referred to our hospital due to abnormality detected by a chest roentgenogram. He had no symptoms except for slight chest oppression. He was found to have a giant coronary aneurysm. It was originated from a coronary artery (left circum flex branch) left ventricular fistula. The orifice of this fistula to the left ventricle was also dilated and formed diverticulum. Ligation of the feeding coronary branch, closure of the aneurysmal fistula in the left ventricular wall and aneurysmectomy were performed under cardiopulmonary bypass. Postoperative course was uneventful. A giant aneurysm originated from a coronary-left ventricular fistula was considered to be very rare.

  10. [Penetrating trauma by foreign body in the left heart ventricle].

    PubMed

    García-Lledó, J A; Moya Mur, J L; Balaguer Recena, J; Novo García, E; Sancho Piedras, J M; Sáiz Beneit, R; Rubio Cantarero, C; Epeldegui Torre, A; Oliva de Anquín, E

    1997-02-01

    We present the case of a patient who suffered a cardiac penetrating trauma due to a 6-cm long steel splinter. He was self-admitted to the emergency room and was asymptomatic. Cardiac trauma was diagnosed by the presence of a foreign body in his chest X-ray. Transthoracic and transesophageal echocardiography showed pericardial effusion and a dense foreign body that crossed the left ventricle from upside down and forward to back. The patient underwent cardiac surgery under extracorporal circulation. A shooting wound was seen on the left ventricular free wall. Transesophageal echocardiography was performed during surgery in order to define the position of the foreign body and to discard lesions due to multidirectional injury. Lesions were repaired and the patient was discharged with no complications. This case report illustrates the possibility of survival after cardiac penetrating trauma, and the role of echocardiography in the diagnosis and surgical repair of this type of trauma.

  11. Regional analysis of the left ventricle of the heart.

    PubMed

    Bernis, François; Léger, Christophe; Eder, Véronique

    2006-04-01

    This paper presents a method to analyze the local wall motion of the left ventricle of the heart. Data are sets of points (obtained from various medical imaging modalities) corresponding to surfaces of the left ventricle, which evolve as a function of time. After re-sampling, the surfaces are segmented in order to create regions of equivalent volume. Then, the local cardiac parameters are estimated: evolution of the regional volumes as a function of time, ejection fraction, end-diastolic and end-systolic volumes, end-diastolic and end-systolic instants. The method has been validated using deformable surfaces synthesized from an ellipsoidal model. It has also been tested in vivo on a set of 59 patients using a specially developed software product, which satisfies severe constraints of robustness, real-time, interactivity and ergonomics. The results obtained are similar to those provided by a reference nuclear medicine examination, but the proposed method is faster and gives a more precise localization of the cardiac wall motion anomalies.

  12. Investigating Shear Wave Physics in a Generic Pediatric Left Ventricular Model via In Vitro Experiments and Finite Element Simulations.

    PubMed

    Caenen, Annette; Pernot, Mathieu; Shcherbakova, Darya Alexandrovna; Mertens, Luc; Kersemans, Mathias; Segers, Patrick; Swillens, Abigail

    2017-02-01

    Shear wave elastography (SWE) is a potentially valuable tool to noninvasively assess ventricular function in children with cardiac disorders, which could help in the early detection of abnormalities in muscle characteristics. Initial experiments demonstrated the potential of this technique in measuring ventricular stiffness; however, its performance remains to be validated as complicated shear wave (SW) propagation characteristics are expected to arise due to the complex non-homogenous structure of the myocardium. In this work, we investigated the (i) accuracy of different shear modulus estimation techniques (time-of-flight (TOF) method and phase velocity analysis) across myocardial thickness and (ii) effect of the ventricular geometry, surroundings, acoustic loading, and material viscoelasticity on SW physics. A generic pediatric (10-15-year old) left ventricular model was studied numerically and experimentally. For the SWE experiments, a polyvinylalcohol replicate of the cardiac geometry was fabricated and SW acquisitions were performed on different ventricular areas using varying probe orientations. Additionally, the phantom's stiffness was obtained via mechanical tests. The results of the SWE experiments revealed the following trends for stiffness estimation across the phantom's thickness: a slight stiffness overestimation for phase speed analysis and a clear stiffness underestimation for the TOF method for all acquisitions. The computational model provided valuable 3-D insights in the physical factors influencing SW patterns, especially the surroundings (water), interface force, and viscoelasticity. In conclusion, this paper presents a validation study of two commonly used shear modulus estimators for different ventricular locations and the essential role of SW modeling in understanding SW physics in the pediatric myocardium.

  13. Differential stress response mechanisms in right and left ventricles.

    PubMed

    Zungu-Edmondson, Makhosazane; Suzuki, Yuichiro J

    2016-01-01

    Right ventricular (RV) failure is the major cause of death among patients with pulmonary hypertension. However, differences between the RV and left ventricle (LV) of the adult heart have not been defined, despite myocytes from these two ventricles originate from different progenitor cells. The lack of such knowledge interferes with developing therapeutic strategies to protect the RV. The goal of this study was to identify possible differences between stress responses in the RV and LV free walls of adult rats. We found that levels of angiogenesis and autophagy/mitophagy proteins are higher in the LV than in the RV. Thus, the LV may be more resistant to stress-induced damage. To test this, isolated rat hearts were subjected to biventricular working heart perfusion and ischemia/reperfusion (I/R) injury. However, I/R was found to cause apoptosis in both LV and RV to a similar extent. One mechanism of cardiac apoptosis involves downregulation of GATA4 transcription factor that controls gene transcription of anti-apoptotic Bcl-xL. Interestingly, only in the RV, I/R caused downregulation of GATA4 and Bcl-xL, suggesting that mechanisms of apoptosis may be different between the two ventricles. Levels of tropomyosin and troponin T were also found to be decreased in response to I/R only in the RV, but not in the LV. Downregulation of the GATA4/Bcl-xL axis and the reduction of tropomyosin and troponin T are RV-specific events that occur in response to stress. This information may be useful for designing RV-specific therapeutic strategies to treat RV failure in pulmonary hypertension patients.

  14. Left ventricle contractile function in trained dogs with cardial hypertrophy.

    PubMed

    Riedhammer, H H; Rafflenbeul, W; Weihe, W H; Krayenbühl, H P

    1976-01-01

    Eight mongrel dogs exercised for 8 weeks by treadmill running at 20 per cent incline 20 to 25 minutes twice daily, 4-5 days/week. Another eight dogs which were kept in the cages for a similar period served as controls. The exercise program was effective in inducing myocardial hypertrophy since the ratio left ventricular weight/body weight was significantly (P less than 0.001) higher in the trained dogs (5.04 g/kg) than in the sedentary animals (3.83 g/kg). In morphine-chloralose anesthesia the dogs were studied by left heart catherization and cineangiography at spontaneous heart rate (run I), at paced heart rate (run II), at paced heart rate following cardiac autonomic nervous blockade by bilateral vagotomy and the administration of propranolol (run III) and during acute pressure loading with methoxzmine at constant heart rate (run IV). Intergroup comparison yielded no significant difference in any hemodynamic or volumetric parameter throughout the entire study. However, with intragroup comparisons between run III and run IV a less significant increase in left ventricular end-diastolic pressure (from 5 to 15 mm Hg; P less than 0.05) was observed in the trained animals than in the control dogs (from 6 to 25 mm Hg; P less than 0.001). Left ventricular end-diastolic volume increased significantly only in the control dogs during acute pressure loading. Mean aortic pressure and left ventricular peak dP/dt increased to a similar extent in both groups. Since in the trained dogs the left ventricle encroaches less on the Frank-Starling mechanism than in normal animals for overcoming an acute pressure burden it is concluded that the development of hypertrophy concomitant with chronic exercise represents an adaptive mechanism with evidence of beneficial consequences for the intrinsic contractile function of the myocardium.

  15. Percutaneous cardioscopy of the left ventricle in patients with myocarditis

    NASA Astrophysics Data System (ADS)

    Uchida, Yasumi; Tomaru, Takanobu; Nakamura, Fumitaka; Oshima, Tomomitsu; Fujimori, Yoshiharu; Hirose, Junichi

    1992-08-01

    The morphology and function of the cardiac chambers have been evaluated clinically using cineventriculography, computed tomography, magnetic resonance imaging, and endomyocardial biopsy. Excluding the invasive technique of biopsy where tissue is actually removed, these other non-invasive techniques reveal only indirect evidence of endocardial and subendocardial pathology and, therefore, allow the potential for misdiagnosis from insufficient data. Fiberoptic examinations, as recently demonstrated in coronary, pulmonary, and peripheral vessels, allow direct observation of pathology otherwise unobtainable. Recently, similar techniques have been applied to examine the cardiac chambers of dogs and the right heart of humans. In this study, we examine the feasibility and safety of percutaneous fiberoptic cardioscopy of the left ventricle in patients with myocarditis.

  16. Functional Strain-Line Pattern in the Human Left Ventricle

    NASA Astrophysics Data System (ADS)

    Pedrizzetti, Gianni; Kraigher-Krainer, Elisabeth; De Luca, Alessio; Caracciolo, Giuseppe; Mangual, Jan O.; Shah, Amil; Toncelli, Loira; Domenichini, Federico; Tonti, Giovanni; Galanti, Giorgio; Sengupta, Partho P.; Narula, Jagat; Solomon, Scott

    2012-07-01

    Analysis of deformations in terms of principal directions appears well suited for biological tissues that present an underlying anatomical structure of fiber arrangement. We applied this concept here to study deformation of the beating heart in vivo analyzing 30 subjects that underwent accurate three-dimensional echocardiographic recording of the left ventricle. Results show that strain develops predominantly along the principal direction with a much smaller transversal strain, indicating an underlying anisotropic, one-dimensional contractile activity. The strain-line pattern closely resembles the helical anatomical structure of the heart muscle. These findings demonstrate that cardiac contraction occurs along spatially variable paths and suggest a potential clinical significance of the principal strain concept for the assessment of mechanical cardiac function. The same concept can help in characterizing the relation between functional and anatomical properties of biological tissues, as well as fiber-reinforced engineered materials.

  17. Torsion of the left ventricle during pacing with MRI tagging

    NASA Astrophysics Data System (ADS)

    Sorger, Jonathan M.; Wyman, Bradley T.; Faris, Owen P.; Hunter, William R.; McVeigh, Elliot R.

    2000-04-01

    In this study the effects of different pacing protocols on left ventricular (LV) torsion was evaluated over the full cardiac cycle. A systolic and diastolic series of Magnetic Resonance Imaging scans were combined and used to calculate the torsion of the LV. The asynchronous contraction resulting from ventricular pacing interferes with the temporal evolution of LV torsion. From these experiments we have shown that measuring torsion is an extremely sensitive indicator of the existence of ectopic excitation. The torsion of the left ventricle was investigated under three different protocols: (1) Right atrial pacing, (2) Right ventricular pacing and (3) Simultaneous pacing from the right ventricular apex and left ventricular base. The temporal evolution of torsion was determined from tagged magnetic resonance images and was evaluated over the full cardiac cycle. The peak twist Tmax for the RA paced heart was 11.09 (+/- 3.54) degrees compared to 6.06 (+/- 1.65) degrees and 6.09 (+/- 0.68) degrees for the RV and Bi-V paced hearts respectively. While biventricular pacing has been shown to increase the synchrony of contraction, it does not preserve the normal physiological twist patterns of the heart.

  18. Patient-specific finite element modeling of the Cardiokinetix Parachute(®) device: effects on left ventricular wall stress and function.

    PubMed

    Lee, Lik Chuan; Ge, Liang; Zhang, Zhihong; Pease, Matthew; Nikolic, Serjan D; Mishra, Rakesh; Ratcliffe, Mark B; Guccione, Julius M

    2014-06-01

    The Parachute(®) (Cardiokinetix, Inc., Menlo Park, California) is a catheter-based device intended to reverse left ventricular (LV) remodeling after antero-apical myocardial infarction. When deployed, the device partitions the LV into upper and lower chambers. To simulate its mechanical effects, we created a finite element LV model based on computed tomography (CT) images from a patient before and 6 months after Parachute(®) implantation. Acute mechanical effects were determined by in silico device implantation (VIRTUAL-Parachute). Chronic effects of the device were determined by adjusting the diastolic and systolic material parameters to better match the 6-month post-implantation CT data and LV pressure data at end-diastole (ED) (POST-OP). Regional myofiber stress and pump function were calculated in each case. The principal finding is that VIRTUAL-Parachute was associated with a 61.2 % reduction in the lower chamber myofiber stress at ED. The POST-OP model was associated with a decrease in LV diastolic stiffness and a larger reduction in myofiber stress at the upper (27.1%) and lower chamber (78.4%) at ED. Myofiber stress at end-systole and stroke volume was little changed in the POST-OP case. These results suggest that the primary mechanism of Parachute(®) is a reduction in ED myofiber stress, which may reverse eccentric post-infarct LV hypertrophy.

  19. Patient-specific finite element modeling of the Cardiokinetix Parachute® device: Effects on left ventricular wall stress and function

    PubMed Central

    Lee, Lik Chuan; Ge, Liang; Zhang, Zhihong; Pease, Matthew; Nikolic, Serjan D.; Mishra, Rakesh; Ratcliffe, Mark B.; Guccione, Julius M.

    2014-01-01

    The Parachute® (Cardiokinetix, Inc., Menlo Park, California) is a catheter-based device intended to reverse left ventricular (LV) remodeling after antero-apical myocardial infarction. When deployed, the device partitions the LV into upper and lower chambers. To simulate its mechanical effects, we created a finite element LV model based on computed tomography (CT) images from a patient before and 6 months after Parachute® implantation. Acute mechanical effects were determined by in-silico device implantation (VIRTUAL-Parachute). Chronic effects of the device were determined by adjusting the diastolic and systolic material parameters to better match the 6-month post-implantation CT data and LV pressure data at end-diastole (ED) (POST-OP). Regional myofiber stress and pump function were calculated in each case. The principal finding is that VIRTUAL-Parachute was associated with a 61.2% reduction in the lower chamber myofiber stress at ED. The POST-OP model was associated with a decrease in LV diastolic stiffness, and a larger reduction in myofiber stress at the upper (27.1%) and lower chamber (78.4%) at ED. Myofiber stress at end-systole and stroke volume were little changed in the POST-OP case. These results suggest that the primary mechanism of Parachute® is a reduction in ED myofiber stress, which may reverse eccentric post-infarct LV hypertrophy. PMID:24793158

  20. Infarcted Left Ventricles Have Stiffer Material Properties and Lower Stiffness Variation: Three-Dimensional Echo-Based Modeling to Quantify In Vivo Ventricle Material Properties.

    PubMed

    Fan, Longling; Yao, Jing; Yang, Chun; Tang, Dalin; Xu, Di

    2015-08-01

    Methods to quantify ventricle material properties noninvasively using in vivo data are of great important in clinical applications. An ultrasound echo-based computational modeling approach was proposed to quantify left ventricle (LV) material properties, curvature, and stress/strain conditions and find differences between normal LV and LV with infarct. Echo image data were acquired from five patients with myocardial infarction (I-Group) and five healthy volunteers as control (H-Group). Finite element models were constructed to obtain ventricle stress and strain conditions. Material stiffening and softening were used to model ventricle active contraction and relaxation. Systolic and diastolic material parameter values were obtained by adjusting the models to match echo volume data. Young's modulus (YM) value was obtained for each material stress-strain curve for easy comparison. LV wall thickness, circumferential and longitudinal curvatures (C- and L-curvature), material parameter values, and stress/strain values were recorded for analysis. Using the mean value of H-Group as the base value, at end-diastole, I-Group mean YM value for the fiber direction stress-strain curve was 54% stiffer than that of H-Group (136.24 kPa versus 88.68 kPa). At end-systole, the mean YM values from the two groups were similar (175.84 kPa versus 200.2 kPa). More interestingly, H-Group end-systole mean YM was 126% higher that its end-diastole value, while I-Group end-systole mean YM was only 29% higher that its end-diastole value. This indicated that H-Group had much greater systole-diastole material stiffness variations. At beginning-of-ejection (BE), LV ejection fraction (LVEF) showed positive correlation with C-curvature, stress, and strain, and negative correlation with LV volume, respectively. At beginning-of-filling (BF), LVEF showed positive correlation with C-curvature and strain, but negative correlation with stress and LV volume, respectively. Using averaged values of two groups

  1. Left ventricle remodelling by double-patch sandwich technique

    PubMed Central

    Tappainer, Ernesto; Fiorani, Vinicio; Pederzolli, Nicola; Manfredi, Jacopo; Nocchi, Andrea; Zogno, Mario

    2007-01-01

    Background The sandwich double-patch technique was adopted as an alternative method for reconstruction of the left ventricle after excision of postinfarction dysfunctional myocardium to solve technical problems due to the thick edges of the ventricular wall. Methods Over a 5-year period, 12 of 21 patients with postinfarction antero-apical left ventricular aneurysm had thick wall edges after wall excision. It was due to akinetic muscular thick tissue in 6 cases, while in the other 6 with classic fibrous aneurysm, thick edges remained after the cut of the border zone. The ventricular opening was sandwiched between two patches and this is a technique which is currently used for the treatment of the interventricular septum rupture. In our patients the patches are much smaller than the removed aneurysm and they were sutured simply by a single row of single stitches. However, in contrast to interventricular septum rupture where the patches loosen the tension of the tissues, in our patients the patches pull strongly and restrain the walls by fastening their edges and supporting tight stitches. In this way they could narrow the cavity and close the ventricle. Results The resected area varied from 5 × 4 to 8 × 8 cm. Excision was extended into the interventricular septum in 5 patients, thus opening the right ventricle. CABG was performed on all patients but two. Left ventricular volumes and the ejection fraction changed significantly: end-systolic volume 93.5 ± 12.4 to 57.8 ± 8.9 ml, p < 0.001; end-diastolic volume 157.2 ± 16.7 to 115.3 ± 14.9 ml, p < 0.001; ejection fraction 40.3 ± 4.2 to 49.5 ± 5.7%, p < 0.001. All patients did well. One patient suffered from bleeding, which was not from the wall suture, and another had a left arm paresis. The post-operative hospital stay was 5 to 30 days with a mean 10.5 ± 7.5 days/patient. At follow-up, 9 to 60 months mean 34, all patients were symptom-free. NYHA class 2.5 ± 0.8 changed to 1.2 ± 0.4, p < 0.001. Conclusion The

  2. Passive and active ventricular elastances of the left ventricle

    PubMed Central

    Zhong, Liang; Ghista, Dhanjoo N; Ng, Eddie YK; Lim, Soo T

    2005-01-01

    Background Description of the heart as a pump has been dominated by models based on elastance and compliance. Here, we are presenting a somewhat new concept of time-varying passive and active elastance. The mathematical basis of time-varying elastance of the ventricle is presented. We have defined elastance in terms of the relationship between ventricular pressure and volume, as: dP = EdV + VdE, where E includes passive (Ep) and active (Ea) elastance. By incorporating this concept in left ventricular (LV) models to simulate filling and systolic phases, we have obtained the time-varying expression for Ea and the LV-volume dependent expression for Ep. Methods and Results Using the patient's catheterization-ventriculogram data, the values of passive and active elastance are computed. Ea is expressed as: ; Epis represented as: . Ea is deemed to represent a measure of LV contractility. Hence, Peak dP/dt and ejection fraction (EF) are computed from the monitored data and used as the traditional measures of LV contractility. When our computed peak active elastance (Ea,max) is compared against these traditional indices by linear regression, a high degree of correlation is obtained. As regards Ep, it constitutes a volume-dependent stiffness property of the LV, and is deemed to represent resistance-to-filling. Conclusions Passive and active ventricular elastance formulae can be evaluated from a single-beat P-V data by means of a simple-to-apply LV model. The active elastance (Ea) can be used to characterize the ventricle's contractile state, while passive elastance (Ep) can represent a measure of resistance-to-filling. PMID:15707494

  3. Disturbed myocardial connexin 43 and N-cadherin expressions in hypoplastic left heart syndrome and borderline left ventricle.

    PubMed

    Mahtab, Edris A F; Gittenberger-de Groot, Adriana C; Vicente-Steijn, Rebecca; Lie-Venema, Heleen; Rijlaarsdam, Marry E B; Hazekamp, Mark G; Bartelings, Margot M

    2012-12-01

    Borderline left ventricle is the left ventricular morphology at the favorable end of the hypoplastic left heart syndrome. In contrast to the severe end, it is suitable for biventricular repair. Wondering whether it is possible to identify cases suitable for biventricular repair from a developmental viewpoint, we investigated the myocardial histology of borderline and severely hypoplastic left ventricles. Postmortem specimens of neonatal, unoperated human hearts with severe hypoplastic left heart syndrome and borderline left ventricle were compared with normal specimens and hearts from patients with transposition of the great arteries. After tissue sampling of the lateral walls of both ventricles, immunohistochemical and immunofluorescence stainings against cardiac troponin I, N-cadherin, and connexin 43, important for proper cardiac differentiation, were done. All severely hypoplastic left hearts (7/7) and most borderline left ventricle hearts (4/6) showed reduced sarcomeric expressions of troponin I in left and right ventricles. N-cadherin and connexin 43 expressions were reduced in intercalated disks. The remaining borderline left ventricle hearts (2/6) were histologically closer to control hearts. Four of 6 borderline left ventricle hearts showed myocardial histopathology similar to the severely hypoplastic left hearts. The remainder were similar to normal hearts. Our results and knowledge regarding the role of epicardial-derived cells in myocardial differentiation lead us to postulate that an abnormal epicardial-myocardial interaction could explain the observed histopathology. Defining the histopathologic severity with preoperative myocardial biopsy samples of hearts with borderline left ventricle might provide a diagnostic tool for preoperative decision making. Copyright © 2012 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

  4. Automatic finite element generators

    NASA Technical Reports Server (NTRS)

    Wang, P. S.

    1984-01-01

    The design and implementation of a software system for generating finite elements and related computations are described. Exact symbolic computational techniques are employed to derive strain-displacement matrices and element stiffness matrices. Methods for dealing with the excessive growth of symbolic expressions are discussed. Automatic FORTRAN code generation is described with emphasis on improving the efficiency of the resultant code.

  5. False aneurysm of the left ventricle due to a penetrating chest wound.

    PubMed

    Badui, E; Madrid, R; Ayala, F; Enciso, R; Verdin, R

    1991-11-01

    A 24-year-old white man had a knife chest wound, and four months after this event, manifested progressive dyspnea. A false aneurysm of the left ventricle was diagnosed by 2D echocardiogram. Surgical resection of the aneurysmal sac with closure of the orifice of the lateral wall of the left ventricle was performed successfully.

  6. Left ventricle segmentation in MRI via convex relaxed distribution matching.

    PubMed

    Nambakhsh, Cyrus M S; Yuan, Jing; Punithakumar, Kumaradevan; Goela, Aashish; Rajchl, Martin; Peters, Terry M; Ayed, Ismail Ben

    2013-12-01

    A fundamental step in the diagnosis of cardiovascular diseases, automatic left ventricle (LV) segmentation in cardiac magnetic resonance images (MRIs) is still acknowledged to be a difficult problem. Most of the existing algorithms require either extensive training or intensive user inputs. This study investigates fast detection of the left ventricle (LV) endo- and epicardium surfaces in cardiac MRI via convex relaxation and distribution matching. The algorithm requires a single subject for training and a very simple user input, which amounts to a single point (mouse click) per target region (cavity or myocardium). It seeks cavity and myocardium regions within each 3D phase by optimizing two functionals, each containing two distribution-matching constraints: (1) a distance-based shape prior and (2) an intensity prior. Based on a global measure of similarity between distributions, the shape prior is intrinsically invariant with respect to translation and rotation. We further introduce a scale variable from which we derive a fixed-point equation (FPE), thereby achieving scale-invariance with only few fast computations. The proposed algorithm relaxes the need for costly pose estimation (or registration) procedures and large training sets, and can tolerate shape deformations, unlike template (or atlas) based priors. Our formulation leads to a challenging problem, which is not directly amenable to convex-optimization techniques. For each functional, we split the problem into a sequence of sub-problems, each of which can be solved exactly and globally via a convex relaxation and the augmented Lagrangian method. Unlike related graph-cut approaches, the proposed convex-relaxation solution can be parallelized to reduce substantially the computational time for 3D domains (or higher), extends directly to high dimensions, and does not have the grid-bias problem. Our parallelized implementation on a graphics processing unit (GPU) demonstrates that the proposed algorithm

  7. Transmural distribution of myocardial infarction: difference between the right and left ventricles in a canine model

    SciTech Connect

    Ohzono, K.; Koyanagi, S.; Urabe, Y.; Harasawa, Y.; Tomoike, H.; Nakamura, M.

    1986-07-01

    The evolution of myocardial infarction 24 hours after ligating both the right coronary artery and the obtuse marginal branch of the left circumflex coronary artery was examined in 33 anesthetized dogs. Postmortem coronary angiography and a tracer microsphere technique were used to determine risk areas and their collateral blood flows, respectively. The mean weight of the risk areas was 11.3 +/- 0.5 g (mean +/- SEM) in the right ventricle and 10.5 +/- 0.9 g in the left ventricle (NS). The weight of infarcted tissue was 5.7 +/- 0.7 g in the right ventricle and 5.2 +/- 0.9 g in the left ventricle (NS). In both ventricles, infarct weight was linearly related to risk area size, and the percent of risk area necrosis was inversely correlated with the extent of collateral flow at 24 hours of coronary ligation, defined as the mean myocardial blood flow inside the central risk area. Ratios of infarct to risk area between the subendocardial and subepicardial layers were 0.76 +/- 0.06 and 0.28 +/- 0.05 in the right and left ventricles, respectively (p less than 0.01, between ventricles, n = 31), which coincided well with subendocardial-to-subepicardial-flow ratios at 24 hours, ie, 0.86 +/- 0.04 in the right ventricle and 0.32 +/- 0.06 in the left ventricle (p less than 0.01). The regional distribution of myocardial infarction correlated well with flow distribution inside the risk area; the slope of these relations was similar between the subendocardium and subepicardium in the right ventricle, whereas in the left ventricle it was larger in the subendocardium than in the subepicardium. Thus, in the dog, the inherent change in the regional distribution of coronary collateral blood flow is an important modifier in the evolution of myocardial infarction, especially in the left ventricle.

  8. Cardiac microvascular rarefaction in hyperthyroidism-induced left ventricle dysfunction.

    PubMed

    Freitas, Felipe; Estato, Vanessa; Carvalho, Vinícius Frias; Torres, Rafael Carvalho; Lessa, Marcos Adriano; Tibiriçá, Eduardo

    2013-10-01

    The pathophysiology underlying hyperthyroidism-induced left ventricle (LV) dysfunction and hypertrophy directly involves the heart and indirectly involves the neuroendocrine systems. The effects of hyperthyroidism on the microcirculation are still controversial in experimental models. We investigated the effects of hyperthyroidism on the cardiac function and microcirculation of an experimental rat model. Male Wistar rats (170-250 g) were divided into two groups: the euthyroid group (n = 10), which was treated with 0.9% saline solution, and the hyperthyroid group (n = 10), which was treated with l-thyroxine (600 μg/kg/day, i.p.) during 14 days. An echocardiographic study was performed to evaluate the alterations in cardiac function, structure and geometry. The structural capillary density and the expression of angiotensin II AT1 receptor in the LV were analyzed using histochemistry and immunohistochemistry, respectively. Hyperthyroidism was found to induce profound cardiovascular alterations, such as systolic hypertension, tachycardia, LV dysfunction, cardiac hypertrophy, and myocardial fibrosis. This study demonstrates the existence of structural capillary rarefaction and the down-regulation of the cardiac angiotensin II AT1 receptor in the myocardium of hyperthyroid rats in comparison with euthyroid rats. Microvascular rarefaction may be involved in the pathophysiology of hyperthyroidism-induced cardiovascular alterations. © 2013 John Wiley & Sons Ltd.

  9. Comparative stereology of the mouse and finch left ventricle.

    PubMed

    Bossen, E H; Sommer, J R; Waugh, R A

    1978-01-01

    The volume fractions and surface per unit cell volume of some subcellular components of the left ventricles of the finch and mouse were quantitated by stereologic techniques. These species were chosen for study because they have similar heart rates but differ morphologically in some respects: fiber diameter is larger in the mouse; the mouse has transverse tubules while the finch does not; and the finch has a form of junctional sarcoplasmic reticulum (JSR), extended JSR (EJSR), located in the cell interior with no direct plasmalemmal contact, while the mouse interior JSR (IJSR) abuts on transverse tubules. Our data show that the volume fraction (Vv) and surface area per unit cell volume (Sv) of total SR, and free SR (FSR) are similar. The volume fractions of mitochondria, myofibrils, and total junctional SR were also similar. The Sv of the cell surface of the finch was similar to the Sv of the cell surface of the mouse (Sv-plasmalemma plus Sv of the transverse tubules). The principal difference was in the distribution of JSR; the mouse peripheral JSR (PJSR) represents only 9% of the total JSR, while the finch PJSR accounts for 24% of the bird's JSR. The similar volume fractions of total junctional SR (PJSR + EJSR in the finch; PJSR + IJSR in the mouse) suggest that the EJSR is not an embryologic remnant, and raises the possibility that some function of JSR is independent of plasmalemmal contact.

  10. Fast left ventricle tracking using localized anatomical affine optical flow.

    PubMed

    Queirós, Sandro; Vilaça, João L; Morais, Pedro; Fonseca, Jaime C; D'hooge, Jan; Barbosa, Daniel

    2017-02-16

    In daily clinical cardiology practice, left ventricle (LV) global and regional function assessment is crucial for disease diagnosis, therapy selection and patient follow-up. Currently, this is still a time-consuming task, spending valuable human resources. In this work, a novel fast methodology for automatic LV tracking is proposed based on localized anatomically constrained affine optical flow. This novel method can be combined to previously proposed segmentation frameworks or manually delineated surfaces at an initial frame to obtain fully delineated datasets and, thus, assess both global and regional myocardial function. Its feasibility and accuracy was investigated in three distinct public databases, namely in realistically simulated 3D ultrasound (US), clinical 3D echocardiography and clinical cine cardiac magnetic resonance (CMR) images. The method showed accurate tracking results in all databases, proving its applicability and accuracy for myocardial function assessment. Moreover, when combined to previous state-of-the-art segmentation frameworks, it outperformed previous tracking strategies in both 3D US and CMR data, automatically computing relevant cardiac indices with smaller biases and narrower limits of agreement compared to reference indices. Simultaneously, the proposed localized tracking method showed to be suitable for online processing, even for 3D motion assessment. Importantly, although here evaluated for LV tracking only, this novel methodology is applicable for tracking of other target structures with minimal adaptations. This article is protected by copyright. All rights reserved.

  11. Nonuniform blood flow in the canine left ventricle.

    PubMed

    Flynn, A E; Coggins, D L; Austin, R E; Muehrcke, D D; Aldea, G S; Goto, M; Doucette, J W; Hoffman, J I

    1990-11-01

    In order to investigate the relationship between coronary perfusion pressure and blood flow distribution in the left ventricle (LV), we measured myocardial blood flow in small regions using radioactive microspheres in six anesthetized, open-chest dogs. Mean coronary perfusion pressure (CPP) was controlled with a femoral artery to left main coronary artery shunt which included a pressurized, servo-controlled blood reservoir. In each dog, we measured flow in 192 regions of the LV free wall (mean weight per region = 206 +/- 38 mg) at different perfusion pressures. At CPP = 80 mm Hg, blood flow to individual regions varied fourfold (0.30 to 1.18 ml/min/g; relative dispersion (RD) = 21.8 +/- 2.3%). At CPP = 50 mm Hg, flow varied over sevenfold (0.08 to 0.60 ml/min/g; RD = 42.8 +/- 10%; P less than 0.01 vs 80 mm Hg). This relationship between flow variability and CPP was present within individual LV layers as well between layers and is much higher than the error associated with the microsphere technique. We conclude that blood flow to small regions of the LV is markedly nonuniform. This heterogeneity becomes more profound at lower CPP. These findings suggest that (1) global measurements of coronary flow must be interpreted with caution, and (2) even in hearts with normal coronary arteries some regions of the LV are more susceptible to ischemia than others. In addition, these findings may help explain the patchy nature of myocardial damage that occurs following periods of low coronary pressure or inadequate myocardial protection during cardiopulmonary bypass.

  12. Measurements, modeling, control and simulation - as applied to the human left ventricle for purposeful physiological monitoring.

    NASA Technical Reports Server (NTRS)

    Ghista, D. N.; Rasmussen, D. N.; Linebarger, R. N.; Sandler, H.

    1971-01-01

    Interdisciplinary engineering research effort in studying the intact human left ventricle has been employed to physiologically monitor the heart and to obtain its 'state-of-health' characteristics. The left ventricle was selected for this purpose because it plays a key role in supplying energy to the body cells. The techniques for measurement of the left ventricular geometry are described; the geometry is effectively displayed to bring out the abnormalities in cardiac function. Methods of mathematical modeling, which make it possible to determine the performance of the intact left ventricular muscle, are also described. Finally, features of a control system for the left ventricle for predicting the effect of certain physiological stress situations on the ventricle performance are discussed.

  13. Quantification of protein expression changes in the aging left ventricle of Rattus norvegicus.

    PubMed

    Grant, Jennifer E; Bradshaw, Amy D; Schwacke, John H; Baicu, Catalin F; Zile, Michael R; Schey, Kevin L

    2009-09-01

    As the heart ages, electrophysiological and biochemical changes can occur, and the ventricle in many cases loses distensibility, impairing diastolic function. How the proteomic signature of the aged ventricle is unique in comparison to young hearts is still under active investigation. We have undertaken a quantitative proteomics study of aging left ventricles (LVs) utilizing the isobaric Tagging for Relative and Absolute Quantification (iTRAQ) methodology. Differential protein expression was observed for 117 proteins including proteins involved in cell signaling, the immune response, structural proteins, and proteins mediating responses to oxidative stress. For many of these proteins, this is the first report of an association with the aged myocardium. Additionally, two proteins of unknown function were identified. This work serves as the basis for making future comparisons of the aged left ventricle proteome to that of left ventricles obtained from other models of disease and heart failure.

  14. Left ventricle surface reconstruction from volumetric CT images by the fusion of clustering and active contours

    NASA Astrophysics Data System (ADS)

    Fan, Li; Chen, Chang W.

    1998-07-01

    This paper presents an integrated scheme to extract and reconstruct left ventricle chambers from CT volumetric image sequences. An accurate extraction of left ventricle chambers is a crucial step towards cardiac dynamics analysis based on image sequences, a very much desired non-invasive technique for heart disease diagnosis and monitoring. The integrated approach aims at solving two major problems in cardiac image segmentation: imaging related ambiguity and anatomy related ambiguity. The K-means clustering with Gibb's random field constraints is able to resolve the imaging related ambiguity to obtain robust segmentation even when the intensity of the left ventricle exhibits spatially varying distribution. The active contour models incorporating a priori shape knowledge is able to resolve the anatomy related ambiguity to estimate the valve that separates the left ventricle from left atrium and aorta but is indistinguishable in the given images due to motion and partial volume effects. The fusion of the clustering and active contour models enables an integrated reconstruction of left ventricle chambers from the CT image sequences. Preliminary results show that the proposed scheme can produce extracted left ventricle chambers that compare favorably with the manually delineated chambers by a skilled operator. However, this proposed scheme is fast and reproducible.

  15. Adrenergic desensitization in left ventricle from streptozotocin diabetic swine.

    PubMed

    Roth, D A; White, C D; Hamilton, C D; Hall, J L; Stanley, W C

    1995-10-01

    Patients with diabetes mellitus that exhibit cardiac pump failure display compromised stroke volume, ejection fraction, and slower rates of rise and fall of left ventricular (LV) dP/dt in the absence of ischemic injury. We hypothesized that diabetic cardiomyopathy may involve decrements in adrenergic sensitivity, with specific molecular alterations in the beta-adrenergic receptor (beta AR)- G protein- adenylyl cyclase (AC) signal transduction system. We assessed the effects of 3 months of streptozotocin-induced diabetes (125 mg/kg i.v.; DIAB, n = 10) on myocardial signal transduction in mini-pigs. DIAB were hyperglycemic compared to controls (CON, n = 10; 20.92 +/- 2.64 v 5.24 +/- 0.35 mM glucose), and had lower fasting insulin levels (6.46 +/- 0.97 v 13.68 +/- 3.91 microU/ml). Transmural LV free wall homogenates from DIAB exhibited similar beta AR density as CON, but decreased cAMP production (pmol cAMP/mg prot.min) using these pharmacological stimulators: 10 microM Isoproterenol plus 100 microM GTP (74 +/- 5 v 97 +/- 11); 100 microM Gpp(NH)p (116 +/- 7 v 161 +/- 17); 10 mM fluoride ion (266 +/- 16 v 324 +/- 25). No differences between DIAB and CON were observed when stimulated by 100 microM forskolin (440 +/- 20 v 429 +/- 33), suggesting no alterations in the catalytic subunit of AC. In DIAB, quantitative immunoblotting indicated slightly depressed levels of Gs (552 +/- 44 v 630 +/- 59 pmol/g ww; NS), but a significant redistribution of alpha s from the sarcolemma to the cytosol (32.7 +/- 0.82% v 25.9 +/- 1.7%). Significantly elevated levels of cardiac Gi were seen in DIAB homogenates compared to CON ventricles (2326 +/- 145 v 1522 +/- 181 pmol/g ww), with no alpha i subunit redistribution. We conclude that despite maintained beta AR density, receptor-dependent and G protein-dependent stimulation of AC is depressed so that streptozotocin-induced diabetic LV is affected by increased cardiac Gi, redistribution of Gs alpha to the cytosol, and an increase in the Gi

  16. [DEFORMITY OF LEFT VENTRICLE WALLS IN PATIENTS WITH AORTAL VALVE STENOSIS].

    PubMed

    Trembovetskaya, E M

    2015-04-01

    Parameters of longitudinal deformity of left ventricle walls in patients, suffering aortal valve stenosis (AVS), were analyzed. While the process of heart contraction in norm and in AVS occurs, longitudinal deformity is expressed maximally in its apical divisions. AVS deformity of apical divisions of left ventricle, as well as middle divisions of interventricular septum and lower wall, practically did not differ from such in norm, and deformity of basal divisions of all walls and middle divisions of posterior, lateral and anterior walls of left ventricle was trustworthy less than a norm. Thus, a reduction of the deformity indices in basal divisions of left ventricle and middle segments of its posterior, lateral and anterior walls in patients, suffering AVS with preserved output fraction, precedes the disorders of its hemodynamics and constitutes a predictor for the cardiac output reduction.

  17. An acquired Gerbode defect from the left ventricle to the coronary sinus following mitral valve replacement.

    PubMed

    Collis, Richard; Afoke, Jonathan; McGregor, Christopher Ga

    2017-06-01

    We report the management of an acquired Gerbode defect, from the left ventricle to the coronary sinus, following mechanical mitral valve replacement. Following a failed percutaneous closure, surgical patch closure of the defect was performed. © 2017 Wiley Periodicals, Inc.

  18. A new technique in advancing the catheter from the left atrium to the left ventricle.

    PubMed

    Wennevold, A

    1980-01-01

    A technique is described by which a catheter is advanced from the left atrium to the left ventricle during a right heart catheterization via the leg. A loop in the catheter is created by the clockwise twisting of the catheter while it is gently pushed against the posterior left wall of the left atrium. The catheter is then pulled back and is twisted counter-clockwise. The catheter has to be soft, and biplane fluroscopy is required. During a 16-month period 162 consecutive infants and children had heart catheterization performed, during which a pediatric NIH catheter was passed to the left atrium. The loop-technique was attempted in 95 patients and was successful in 66 patients. One or two attempts were usually in 95 patients and was successful in 66 patients. One or two attempts were usually sufficient. No complications were encountered apart from two brief episodes of bradycardia. The technique is easy to perform with a reasonable success rate. It seems most useful in infants in whom 5F catheters are used.

  19. Computational Modeling of Left Ventricle Dynamics and Flow Based on Ultrasonographic Data

    NASA Astrophysics Data System (ADS)

    Iwase, Hidehito; Liu, Hao; Fujimoto, Shinichi; Himeno, Ryutaro

    A computational model combined ultrasonographic data and computational fluid dynamics (CFD) was developed and applied to an anatomically realistic model of the human left ventricle. The proposed methodology employs but not limited to ultrasonographic scans of a human left ventricle to obtain a set of time-varying images of morphology and dynamics of the left ventricle, which are utilized in generating a dynamic geometrical model for blood flow simulation. A so-called Two-Chamber-View modeling method has been proposed to obtain digitized anatomical images on two mutually orthogonal planes that cut through the left ventricle chamber along the long axis from base to apex, and from which two endocardial borderlines in the two planes are extracted for each time frame. Endocardial contours in the short-axis plane is approximated as an ellipse with two radii determined from the extracted endocardial borderlines in the two long-axis planes and stacked up from base to apex to generate a fully three-dimensional geometric model. Physiological conditions of inflow/outflow at orifices notionally representing the mitral and aortic vales are obtained also based on the ultrasonographic images by deriving flow rates at the orifices directly through calculating time-variation-rate of the left ventricle volume. Computational modeling of left ventricle hemodynamics is accomplished by using an in-house NS solver with specific modification for blood flow in heart chamber. The reconstructed CFD model well captures the three-dimensional dynamics of endocardial wall in terms of contraction and expansion phases in the left ventricle; and the dominant fluid dynamics involving vortices and swirls are simulated reasonably. Our computed results indicate that realistic modeling of both geometry and physiological conditions of left ventricle is of great importance in correctly predicting the behavior of the dominant vortex flow and their influence on the heart function.

  20. Abnormal origin of the left subclavian artery from the left pulmonary artery in a patient with double outlet right ventricle.

    PubMed

    Lee, Youngok; Hong, Seong Wook

    2014-02-01

    Anomalous aortic origin of the left subclavian artery (LSCA) from the left pulmonary artery (LPA) is a rare congenital cardiac malformation. We describe a case of LSCA from the LPA via ductus arteriosus in association with a double-outlet right ventricle, which never has been reported previously in Korea.

  1. Selection of reference genes for gene expression studies in heart failure for left and right ventricles.

    PubMed

    Li, Mengmeng; Rao, Man; Chen, Kai; Zhou, Jianye; Song, Jiangping

    2017-07-15

    Real-time quantitative reverse transcriptase-PCR (qRT-PCR) is a feasible tool for determining gene expression profiles, but the accuracy and reliability of the results depends on the stable expression of selected housekeeping genes in different samples. By far, researches on stable housekeeping genes in human heart failure samples are rare. Moreover the effect of heart failure on the expression of housekeeping genes in right and left ventricles is yet to be studied. Therefore we aim to provide stable housekeeping genes for both ventricles in heart failure and normal heart samples. In this study, we selected seven commonly used housekeeping genes as candidates. By using the qRT-PCR, the expression levels of ACTB, RAB7A, GAPDH, REEP5, RPL5, PSMB4 and VCP in eight heart failure and four normal heart samples were assessed. The stability of candidate housekeeping genes was evaluated by geNorm and Normfinder softwares. GAPDH showed the least variation in all heart samples. Results also indicated the difference of gene expression existed in heart failure left and right ventricles. GAPDH had the highest expression stability in both heart failure and normal heart samples. We also propose using different sets of housekeeping genes for left and right ventricles respectively. The combination of RPL5, GAPDH and PSMB4 is suitable for the right ventricle and the combination of GAPDH, REEP5 and RAB7A is suitable for the left ventricle. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Ductal stenting retrains the left ventricle in transposition of great arteries with intact ventricular septum.

    PubMed

    Sivakumar, Kothandam; Francis, Edwin; Krishnan, Prasad; Shahani, Jagdish

    2006-11-01

    In late presenters with transposition of the great arteries, intact ventricular septum, and regressing left ventricle, left ventricular retraining by pulmonary artery banding and aortopulmonary shunt is characterized by a stormy postoperative course and high costs. Ductal stenting in the cardiac catheterization laboratory is conceptualized to retrain the left ventricle with less morbidity. Recanalization and transcatheter stenting of patent ductus arteriosus was performed in patients with transposition to induce pressure and volume overload to the regressing left ventricle. Serial echocardiographic monitoring of left ventricular shape, mass, free wall thickness, and volumes was done, and once the left ventricle was adequately prepared, an arterial switch was performed. The ductal stent was removed and the remaining surgical steps were similar to a 1-stage arterial switch operation. Postoperative course, need for inotropic agents, and left ventricular function were monitored. Ductal stenting in 2 patients aged 3 months resulted in improvement of indexed left ventricular mass from 18.9 to 108.5 g/m2, left ventricular free wall thickness from 2.5 to 4.8 mm, and indexed left ventricular volumes from 7.6 to 29.5 mL/m2 within 3 weeks. Both patients underwent arterial switch (bypass times 125 and 158 minutes) uneventfully, needed inotropic agents and ventilatory support for 3 days, and were discharged in 8 and 10 days. Ductal stenting is a less morbid method of left ventricular retraining in transposition of the great arteries with regressed left ventricle. Its major advantages lie in avoiding pulmonary artery distortion and neoaortic valve regurgitation resulting from banding and also in avoiding thoracotomy.

  3. Regional myocardial shape and dimensions of the working isolated canine left ventricle

    NASA Technical Reports Server (NTRS)

    Ritman, E.; Tsuiki, K.; Donald, D.; Wood, E. H.

    1975-01-01

    Angiographic experiments were performed on isolated canine left ventricle preparations using donor dog to supply blood to the coronary circulation via a rotary pump to control coronary flow. The angiographic record was transferred from video tape to video disk for detailed uninterrupted sequential analysis at a frequency of 60 fields/sec. It is shown that the use of a biplane X-ray technique and a metabolically supported isolated canine left ventricle preparation provides an angiographically ideal means of measuring the mechanical dynamics of the myocardium while the intact left ventricular myocardial structure and electrical activation pattern retain most of the in situ ventricular characteristics. In particular, biplane X-ray angiography of the left ventricle can provide estimates of total ventricular function such as ejection fraction, stroke volume, and myocardial mass correct to within 15% under the angiographically ideal conditions of the preparation.

  4. Double outlet right ventricle with unilateral absence of left pulmonary artery.

    PubMed

    Ugurlucan, Murat; Arslan, Ahmet H; Yildiz, Yahya; Ay, Sibel; Cicek, Sertac

    2013-06-01

    Congenital absence of unilateral pulmonary artery, either as a primary defect or in combination with other congenital cardiovascular malformations, is very rare. Double outlet right ventricle pathology in combination with unilateral absence of pulmonary artery has only been reported once in the literature. In this report, we present our experience with double outlet right ventricle with unilateral absence of left pulmonary artery in a 3-year-old female patient who underwent a palliative procedure and was scheduled for correction.

  5. Diverticular and Aneurysmal Structures of the Left Ventricle in Adults

    PubMed Central

    Makkuni, Premraj; Kotler, Morris N.; Figueredo, Vincent M.

    2010-01-01

    Left ventricular outpouchings are increasingly detected on cardiovascular imaging. Herein, we describe the case of a 45-year-old man who underwent noncardiac preoperative imaging and was found to have an asymptomatic left ventricular outpouching. The patient underwent successful surgical repair of the structure. When left ventricular outpouchings are detected, the main differential diagnoses are pseudoaneurysm, aneurysm, and diverticulum. The outcomes for these conditions differ substantially, and accurate diagnosis can be crucial in making clinical decisions. We review the relevant medical literature, outline the natural history of these left ventricular abnormalities, and discuss options in regard to their management. PMID:21224951

  6. Transthoracic delivery of large devices into the left ventricle through the right ventricle and interventricular septum: preclinical feasibility

    PubMed Central

    2013-01-01

    Background We aim to deliver large appliances into the left ventricle through the right ventricle and across the interventricular septum. This transthoracic access route exploits immediate recoil of the septum, and lower transmyocardial pressure gradient across the right versus left ventricular free wall. The route may enhance safety and allow subxiphoid rather than intercostal traversal. Methods The entire procedure was performed under real-time CMR guidance. An “active” CMR needle crossed the chest, right ventricular free wall, and then the interventricular septum to deliver a guidewire then used to deliver an 18Fr introducer. Afterwards, the right ventricular free wall was closed with a nitinol occluder. Immediate closure and late healing of the unrepaired septum and free wall were assessed by oximetry, angiography, CMR, and necropsy up to four weeks afterwards. Results The procedure was successful in 9 of 11 pigs. One failed because of refractory ventricular fibrillation upon needle entry, and the other because of inadequate guidewire support. In all ten attempts, the right ventricular free wall was closed without hemopericardium. There was neither immediate nor late shunt on oximetry, X-ray angiography, or CMR. The interventricular septal tract fibrosed completely. Transventricular trajectories planned on human CT scans suggest comparable intracavitary working space and less acute entry angles than a conventional atrial transseptal approach. Conclusion Large closed-chest access ports can be introduced across the right ventricular free wall and interventricular septum into the left ventricle. The septum recoils immediately and heals completely without repair. A nitinol occluder immediately seals the right ventricular wall. The entry angle is more favorable to introduce, for example, prosthetic mitral valves than a conventional atrial transseptal approach. PMID:23331459

  7. Morphological three-dimensional analysis of papillary muscles in borderline left ventricles.

    PubMed

    Velasco Forte, Mari N; Nassar, Mohamed; Byrne, Nick; Silva Vieira, Miguel; Pérez, Israel V; Ruijsink, Bram; Simpson, John; Hussain, Tarique

    2017-09-01

    Mitral valve anatomy has a significant impact on potential surgical options for patients with hypoplastic or borderline left ventricle. Papillary muscle morphology is a major component regarding this aspect. The purpose of this study was to use cardiac magnetic resonance to describe the differences in papillary muscle anatomy between normal, borderline, and hypoplastic left ventricles. We carried out a retrospective, observational cardiac magnetic resonance study of children (median age 5.36 years) with normal (n=30), borderline (n=22), or hypoplastic (n=13) left ventricles. Borderline and hypoplastic cases had undergone an initial hybrid procedure. Morphological features of the papillary muscles, location, and arrangement were analysed and compared across groups. All normal ventricles had two papillary muscles with narrow pedicles; however, 18% of borderline and 46% of hypoplastic cases had a single papillary muscle, usually the inferomedial type. In addition, in borderline or hypoplastic ventricles, the supporting pedicle occasionally displayed a wide insertion along the ventricular wall. The length ratio of the superolateral support was significantly different between groups (normal: 0.46±0.08; borderline: 0.39±0.07; hypoplastic: 0.36±0.1; p=0.009). No significant difference, however, was found when analysing the inferomedial type (0.42±0.09; 0.38±0.07; 0.39±0.22, p=0.39). The angle subtended between supports was also similar among groups (113°±17°; 111°±51° and 114°±57°; p=0.99). A total of eight children with borderline left ventricle underwent biventricular repair. There were no significant differentiating features for papillary muscle morphology in this subgroup. The superolateral support can be shorter or absent in borderline or hypoplastic left ventricle cases. The papillary muscle pedicles in these patients often show a broad insertion. These changes have important implications on surgical options and should be described routinely.

  8. Doppler echocardiographic description of double-inlet left ventricle in an Arabian horse.

    PubMed

    Sedacca, Cassidy D; Bright, Janice M; Boon, June

    2010-08-01

    Univentricular atrioventricular (AV) connections are rare and complex congenital cardiac anomalies in which both AV valves communicate into a large, common (single) receiving chamber. The common chamber can be of left, right, or mixed ventricular morphology. Although well documented in people, reports of the double-inlet ventricle malformation are rare in the veterinary literature. This report provides description of an Arabian horse with a double-inlet univentricular connection of left ventricular type, a hypoplastic subpulmonary right ventricle, two muscular ventricular septal defects, and a stenotic mitral valve. Transthoracic Doppler echocardiography enabled antemortem diagnosis, and provided an assessment of intracardiac hemodynamics. The findings indicate that Doppler echocardiography is a useful, noninvasive tool for evaluating equine patients with congenital univentricular AV connections, such as a double-inlet left ventricle.

  9. Regional myocardial shape and dimensions of the working isolated canine left ventricle

    NASA Technical Reports Server (NTRS)

    Ritman, E. L.; Tsuiki, K.; Donald, D.; Wood, E. H.

    1975-01-01

    The extent to which the dynamic shape and dimensions of the isolated left ventricular myocardial wall differ throughout the myocardium and how these differences are characteristic of the anatomic location was demonstrated. The use of a biplane X-ray technique and a metabolically-supported isolated canine left ventricle preparation provided an angiographically ideal means of measuring mechanical dynamics of the myocardium while the intact left ventricular myocardial structure and electrical activation pattern retains most of the in situ ventricular characteristics.

  10. Communication between the left ventricle and right atrium

    PubMed Central

    Barclay, R. S.; Reid, J. M.; Coleman, E. N.; Stevenson, J. G.; Welsh, T. M.; McSwan, N.

    1967-01-01

    A further 15 patients with left ventricular/right atrial communication are reported, 14 of whom were treated surgically. The clinical triad of a ventricular septal defect murmur, cardiac enlargement, and an arteriovenous shunt at atrial level is characteristic of the malformation. Of the 14 patients accorded surgical treatment, one died soon after operation. The remainder are well, with both the electrocardiographic signs of left ventricular hypertrophy and the radiographic evidence of cardiomegaly having undergone regression. Images PMID:4227847

  11. Finite element computational fluid mechanics

    NASA Technical Reports Server (NTRS)

    Baker, A. J.

    1983-01-01

    Finite element analysis as applied to the broad spectrum of computational fluid mechanics is analyzed. The finite element solution methodology is derived, developed, and applied directly to the differential equation systems governing classes of problems in fluid mechanics. The heat conduction equation is used to reveal the essence and elegance of finite element theory, including higher order accuracy and convergence. The algorithm is extended to the pervasive nonlinearity of the Navier-Stokes equations. A specific fluid mechanics problem class is analyzed with an even mix of theory and applications, including turbulence closure and the solution of turbulent flows.

  12. Finite element computational fluid mechanics

    NASA Technical Reports Server (NTRS)

    Baker, A. J.

    1983-01-01

    Finite element analysis as applied to the broad spectrum of computational fluid mechanics is analyzed. The finite element solution methodology is derived, developed, and applied directly to the differential equation systems governing classes of problems in fluid mechanics. The heat conduction equation is used to reveal the essence and elegance of finite element theory, including higher order accuracy and convergence. The algorithm is extended to the pervasive nonlinearity of the Navier-Stokes equations. A specific fluid mechanics problem class is analyzed with an even mix of theory and applications, including turbulence closure and the solution of turbulent flows.

  13. Automatic short axis orientation of the left ventricle in 3D ultrasound recordings

    NASA Astrophysics Data System (ADS)

    Pedrosa, João.; Heyde, Brecht; Heeren, Laurens; Engvall, Jan; Zamorano, Jose; Papachristidis, Alexandros; Edvardsen, Thor; Claus, Piet; D'hooge, Jan

    2016-04-01

    The recent advent of three-dimensional echocardiography has led to an increased interest from the scientific community in left ventricle segmentation frameworks for cardiac volume and function assessment. An automatic orientation of the segmented left ventricular mesh is an important step to obtain a point-to-point correspondence between the mesh and the cardiac anatomy. Furthermore, this would allow for an automatic division of the left ventricle into the standard 17 segments and, thus, fully automatic per-segment analysis, e.g. regional strain assessment. In this work, a method for fully automatic short axis orientation of the segmented left ventricle is presented. The proposed framework aims at detecting the inferior right ventricular insertion point. 211 three-dimensional echocardiographic images were used to validate this framework by comparison to manual annotation of the inferior right ventricular insertion point. A mean unsigned error of 8, 05° +/- 18, 50° was found, whereas the mean signed error was 1, 09°. Large deviations between the manual and automatic annotations (> 30°) only occurred in 3, 79% of cases. The average computation time was 666ms in a non-optimized MATLAB environment, which potentiates real-time application. In conclusion, a successful automatic real-time method for orientation of the segmented left ventricle is proposed.

  14. [Left ventricle assist device: rehabilitation and management programmes].

    PubMed

    D'agrosa-Boiteux, M-C; Geoffroy, E; Dauphin, N; Camilleri, L; Eschalier, R; Cuenin, C; Moisa, A

    2014-09-01

    Progress in the medical management of patients with heart failure with systolic dysfunction has been accompanied by a significant improvement in survival and quality of life. These strategies have also resulted in changes in the clinical profile as well as an increase in the number of patients with advanced heart failure. The technological developments in left ventricular assist devices provide real hope for these patients. This article related our experience of management and the rehabilitation program realized.

  15. Effect of diastolic flow patterns on the function of the left ventricle

    NASA Astrophysics Data System (ADS)

    Seo, Jung Hee; Mittal, Rajat

    2013-11-01

    Direct numerical simulations are used to study the effect of intraventricular flow patterns on the pumping efficiency and the blood mixing and transport characteristics of the left ventricle. The simulations employ a geometric model of the left ventricle which is derived from contrast computed tomography. A variety of diastolic flow conditions are generated for a fixed ejection fraction in order to delineate the effect of flow patterns on ventricular performance. The simulations indicate that the effect of intraventricular blood flow pattern on the pumping power is physiologically insignificant. However, diastolic flow patterns have a noticeable effect on the blood mixing as well as the residence time of blood cells in the ventricle. The implications of these findings on ventricular function are discussed.

  16. Toward automatic finite element analysis

    NASA Technical Reports Server (NTRS)

    Kela, Ajay; Perucchio, Renato; Voelcker, Herbert

    1987-01-01

    Two problems must be solved if the finite element method is to become a reliable and affordable blackbox engineering tool. Finite element meshes must be generated automatically from computer aided design databases and mesh analysis must be made self-adaptive. The experimental system described solves both problems in 2-D through spatial and analytical substructuring techniques that are now being extended into 3-D.

  17. Left Ventricle Hypertrophy, Dilatation and Ejection Fraction Changes Before and After Kidney Transplantation

    PubMed Central

    Tayebi-Khosroshahi, Hamid; Abbasnezhad, Mohsen; Habibzadeh, Afshin; Bakhshandeh, Masumeh; Chaichi, Parastoo

    2013-01-01

    Background Patients with end stage renal disease (ESRD) are at risk of complications in different organs including cardiovascular system. Renal transplantation is the best choice in these patients which diminishes these complications. It is observed that after renal transplantation, cardiac parameters have appropriate improvement. Current study evaluates echocardiographic findings in renal transplant recipients before and after kidney transplantation. Methods In an analytic cross sectional study, 30 patients (50% male, mean age of 45.57 ± 13.32 years) with ESRD who underwent renal transplantation were studied. All patients had echocardiographic studies after the last dialysis before and 6 months after transplantation. Echocardiographic study was done by Color Doppler two dimension methods and left ventricle ejection fraction was measured by Simpson method. All echocardiograms before and after transplantation were interpreted by the same cardiologist. Results Mean left ventricle ejection fraction before and after renal transplantation was 53.83±10.14% and 57.33±4.49%, respectively (P = 0.09). Left ventricle hypertrophy, mitral regurgitation and tricuspid regurgitation existed in 46.7%, 76.7% and 33.3% respectively, which was improved in 30%, 50% and 33.3% after renal transplantation. Conclusion According to the results of current study it is suggested that renal transplantation could improve left ventricle parameters in patients with end stage renal disease.

  18. Fluid-structure interaction in the left ventricle of the human heart coupled with mitral valve

    NASA Astrophysics Data System (ADS)

    Meschini, Valentina; de Tullio, Marco Donato; Querzoli, Giorgio; Verzicco, Roberto

    2016-11-01

    In this paper Direct Numerical Simulations (DNS), implemented using a fully fluid-structure interaction model for the left ventricle, the mitral valve and the flowing blood, and laboratory experiments are performed in order to cross validate the results. Moreover a parameter affecting the flow dynamics is the presence of a mitral valve. We model two cases, one with a natural mitral valve and another with a prosthetic mechanical one. Our aim is to understand their different effects on the flow inside the left ventricle in order to better investigate the process of valve replacement. We simulate two situations, one of a healthy left ventricle and another of a failing one. While in the first case the flow reaches the apex of the left ventricle and washout the stagnant fluid with both mechanical and natural valve, in the second case the disturbance generated by the mechanical leaflets destabilizes the mitral jet, thus further decreasing its capability to penetrate the ventricular region and originating heart attack or cardiac pathologies in general.

  19. Pregnancy Differentially Regulates the Collagens Types I and III in Left Ventricle from Rat Heart

    PubMed Central

    Limon-Miranda, Sarai; Salazar-Enriquez, Diana G.; Muñiz, Jesus; Ramirez-Archila, Mario V.; Sanchez-Pastor, Enrique A.; Andrade, Felipa; Soñanez-Organis, Jose G.; Moran-Palacio, Edgar F.; Virgen-Ortiz, Adolfo

    2014-01-01

    The pathologic cardiac remodeling has been widely documented; however, the physiological cardiac remodeling induced by pregnancy and its reversion in postpartum are poorly understood. In the present study we investigated the changes in collagen I (Col I) and collagen III (Col III) mRNA and protein levels in left ventricle from rat heart during pregnancy and postpartum. Col I and Col III mRNA expression in left ventricle samples during pregnancy and postpartum were analyzed by using quantitative PCR. Data obtained from gene expression show that Col I and Col III in left ventricle are upregulated during pregnancy with reversion in postpartum. In contrast to gene expression, the protein expression evaluated by western blot showed that Col I is downregulated and Col III is upregulated in left ventricle during pregnancy. In conclusion, the pregnancy differentially regulates collagens types I and III in heart; this finding could be an important molecular mechanism that regulates the ventricular stiffness in response to blood volume overload present during pregnancy which is reversed in postpartum. PMID:25147829

  20. Pregnancy differentially regulates the collagens types I and III in left ventricle from rat heart.

    PubMed

    Limon-Miranda, Sarai; Salazar-Enriquez, Diana G; Muñiz, Jesus; Ramirez-Archila, Mario V; Sanchez-Pastor, Enrique A; Andrade, Felipa; Soñanez-Organis, Jose G; Moran-Palacio, Edgar F; Virgen-Ortiz, Adolfo

    2014-01-01

    The pathologic cardiac remodeling has been widely documented; however, the physiological cardiac remodeling induced by pregnancy and its reversion in postpartum are poorly understood. In the present study we investigated the changes in collagen I (Col I) and collagen III (Col III) mRNA and protein levels in left ventricle from rat heart during pregnancy and postpartum. Col I and Col III mRNA expression in left ventricle samples during pregnancy and postpartum were analyzed by using quantitative PCR. Data obtained from gene expression show that Col I and Col III in left ventricle are upregulated during pregnancy with reversion in postpartum. In contrast to gene expression, the protein expression evaluated by western blot showed that Col I is downregulated and Col III is upregulated in left ventricle during pregnancy. In conclusion, the pregnancy differentially regulates collagens types I and III in heart; this finding could be an important molecular mechanism that regulates the ventricular stiffness in response to blood volume overload present during pregnancy which is reversed in postpartum.

  1. A numerical study of the left ventricle using structure-based bio-mechanical model

    NASA Astrophysics Data System (ADS)

    Zhu, Yunfei; Luo, Xiaoyu; Feng, Yaoqi

    A numerical study of the left ventricle using structure-based bio-mechanical model In space environment, microgravity and radiation can have deleterious effects on the cardiovascular system of the astronauts. The work in this paper is part of an ongoing effort to use mathematical models to provide a better understanding of the impact of long-duration spaceflight on the heart and blood vessels. In this study, we develop a computational left ventricle model before and after myocardium infarction based on cardiovascular mechanical theory. The anatomically realistic model has a rule-based fibre structure and a orthotropic structure-based constitutive model. The differences of deformations in the left ventricle before and after infarction are compared in details. In particular, the effects of fiber direction and fiber dispersion are examined. The disarray of both the fiber and sheet orientation is characterized by a dispersion parameter. The left ventricle volume is calculated from the MRI images and used for the optimization of the parameters of the myocardium. We provide the numerical framework for further study on effects of spaceflight on the cardiovascular system.

  2. [Giant negative T waves in idiopathic apical diverticulum of the left ventricle in adults].

    PubMed

    Barboteu, M; Desnos, M; Hagège, A; Dufour, M; Chauvaud, S; Junes, G; Baleynaud, S; Bruneval, P; Guérot, C

    1995-10-01

    Left ventricular diverticula, congenital or acquired, with normal coronary arteries are rare. Apical diverticula are exceptionally rare in the adult. The authors present the clinical, paraclinical, anatomopathological pre- and postoperative data in a case of apical diverticulum of the left ventricle presenting with giant negative T waves. The differential diagnosis of these electrocardiographic changes is discussed, in particular apical cardiomyopathy, especially as the two conditions may be associated.

  3. Increased myocardial ischemia during nitrate therapy: caused by multiple coronary artery-left ventricle fistulae?

    PubMed

    Heper, Gulumser; Kose, Sedat

    2005-01-01

    We present the case of a 54-year-old man who had crescendo angina during nitrate therapy. Selective coronary angiograms showed no atherosclerotic lesions, but did show plexuses of intramural vessels that connected the distal thirds of the left and right coronary systems with the left ventricle. The cause of our patient's increased myocardial ischemia during nitrate therapy may have been the coronary "steal" phenomenon.

  4. A Computational Chemo-Fluidic Modeling for the Investigation of Patient-Specific Left Ventricle Thrombogenesis

    NASA Astrophysics Data System (ADS)

    Mittal, Rajat; Seo, Jung Hee; Abd, Thura; George, Richard T.

    2015-11-01

    Patients recovering from myocardial infarction (MI) are considered at high-risk for cardioembolic stroke due to the formation of left ventricle thrombus (LVT). The formation of LVT is the result of a complex interplay between the fluid dynamics inside the ventricle and the chemistry of coagulation, and the role of LV flow pattern on the thrombogenesis was not well understood. The previous computational study performed with the model ventricles suggested that the local flow residence time is the key variable governing the accumulation of coagulation factors. In the present study, a coupled, chemo-fluidic computational modeling is applied to the patient-specific cases of infracted ventricles to investigate the interaction between the LV hemodynamics and thrombogensis. In collaboration with the Johns Hopkins hospital, patient-specific LV models are constructed using the multi-modality medical imaging data. Blood flow in the left ventricle is simulated by solving the incompressible Navier-Stokes equations and the biochemical reactions for the thrombus formation are modeled with convection-diffusion-reaction equations. The formation and deposition of key coagulation chemical factors are then correlated with the hemodynamic flow metrics to explore the biophysics underlying LVT risk. Supported by the Johns Hopkins Medicine Discovery Fund and NSF Grant: CBET-1511200, Computational resource by XSEDE NSF grant TG-CTS100002.

  5. Skeletal muscle ventricles as left atrial-aortic pumps: short-term studies.

    PubMed

    Hooper, T L; Niinami, H; Hammond, R L; Lu, H; Ruggiero, R; Pochettino, A; Stephenson, L W

    1992-08-01

    In 5 dogs, skeletal muscle ventricles (SMVs) were constructed from the latissimus dorsi muscle and placed in the left hemithorax. After a 3-week vascular delay period, SMVs were electrically preconditioned with 2-Hz stimulation for 6 weeks. At a second operation, SMVs were connected between the left atrium and thoracic aorta by afferent and efferent aortic root homografts, and stimulated to contract in a 1:2 diastolic mode. At a mean left atrial pressure of 12.4 +/- 1.3 mm Hg and a burst stimulation frequency of 33 Hz, SMV stroke volume was initially 43% of that of the native left ventricle, achieving a flow equivalent to 21% of cardiac output (194 +/- 38 versus 902 +/- 85 mL/min). At 50-Hz stimulation, this figure rose to 27% (246 +/- 41 mL/min; p less than 0.05). Skeletal muscle ventricle power output (the product of stroke work and contraction rate) at 33 Hz was 0.016 +/- 0.003 W, increasing to 0.024 +/- 0.004 W at 50 Hz (p less than 0.05), corresponding to 14% and 22%, respectively, of left ventricular power output (0.11 +/- 0.012 W). After 4 hours of continuous pumping, four of the SMVs were still generating flows of more than 70% of starting values and more than 60% of initial power output. This study demonstrates that SMVs can function in the systemic circulation at physiologic left atrial preloads.

  6. Automated axial right ventricle to left ventricle diameter ratio computation in computed tomography pulmonary angiography.

    PubMed

    González, Germán; Jiménez-Carretero, Daniel; Rodríguez-López, Sara; Kumamaru, Kanako K; George, Elizabeth; San José Estépar, Raúl; Rybicki, Frank J; Ledesma-Carbayo, Maria J

    2015-01-01

    Right Ventricular to Left Ventricular (RV/LV) diameter ratio has been shown to be a prognostic biomarker for patients suffering from acute Pulmonary Embolism (PE). While Computed Tomography Pulmonary Angiography (CTPA) images used to confirm a clinical suspicion of PE do include information of the heart, a numerical RV/LV diameter ratio is not universally reported, likely because of lack in training, inter-reader variability in the measurements, and additional effort by the radiologist. This study designs and validates a completely automated Computer Aided Detection (CAD) system to compute the axial RV/LV diameter ratio from CTPA images so that the RV/LV diameter ratio can be a more objective metric that is consistently reported in patients for whom CTPA diagnoses PE. The CAD system was designed specifically for RV/LV measurements. The system was tested in 198 consecutive CTPA patients with acute PE. Its accuracy was evaluated using reference standard RV/LV radiologist measurements and its prognostic value was established for 30-day PE-specific mortality and a composite outcome of 30-day PE-specific mortality or the need for intensive therapies. The study was Institutional Review Board (IRB) approved and HIPAA compliant. The CAD system analyzed correctly 92.4% (183/198) of CTPA studies. The mean difference between automated and manually computed axial RV/LV ratios was 0.03±0.22. The correlation between the RV/LV diameter ratio obtained by the CAD system and that obtained by the radiologist was high (r=0.81). Compared to the radiologist, the CAD system equally achieved high accuracy for the composite outcome, with areas under the receiver operating characteristic curves of 0.75 vs. 0.78. Similar results were found for 30-days PE-specific mortality, with areas under the curve of 0.72 vs. 0.75. An automated CAD system for determining the CT derived RV/LV diameter ratio in patients with acute PE has high accuracy when compared to manual measurements and similar

  7. Computational modelling of left-ventricular diastolic mechanics: effect of fibre orientation and right-ventricle topology.

    PubMed

    Palit, Arnab; Bhudia, Sunil K; Arvanitis, Theodoros N; Turley, Glen A; Williams, Mark A

    2015-02-26

    Majority of heart failure patients who suffer from diastolic dysfunction retain normal systolic pump action. The dysfunction remodels the myocardial fibre structure of left-ventricle (LV), changing its regular diastolic behaviour. Existing LV diastolic models ignored the effects of right-ventricular (RV) deformation, resulting in inaccurate strain analysis of LV wall during diastole. This paper, for the first time, proposes a numerical approach to investigate the effect of fibre-angle distribution and RV deformation on LV diastolic mechanics. A finite element modelling of LV passive inflation was carried out, using structure-based orthotropic constitutive law. Rule-based fibre architecture was assigned on a bi-ventricular (BV) geometry constructed from non-invasive imaging of human heart. The effect of RV deformation on LV diastolic mechanics was investigated by comparing the results predicted by BV and single LV model constructed from the same image data. Results indicated an important influence of RV deformation which led to additional LV passive inflation and increase of average fibre and sheet stress-strain in LV wall during diastole. Sensitivity of LV passive mechanics to the changes in the fibre distribution was also examined. The study revealed that LV diastolic volume increased when fibres were aligned more towards LV longitudinal axis. Changes in fibre angle distribution significantly altered fibre stress-strain distribution of LV wall. The simulation results strongly suggest that patient-specific fibre structure and RV deformation play very important roles in LV diastolic mechanics and should be accounted for in computational modelling for improved understanding of the LV mechanics under normal and pathological conditions. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Dynamic Mode Decomposition Bio-Markers for Left Ventricle Flow

    NASA Astrophysics Data System (ADS)

    Borja, Maria; Martinez-Legazpi, Pablo; Benito, Yolanda; Yotti, Raquel; Fernandez-Aviles, Francisco; Bermejo, Javier; Del Alamo, Juan C.

    2016-11-01

    Dynamic mode decomposition (DMD) is a tool used in the fluid community to extract a set of modes that describe the underling fluid dynamics in a set of flow fields generated experimentally or by numerical simulations. Despite advances in medical imaging, characterization of some cardiac dysfunctions has remained a challenge and diagnosis is often subjective. This study presents a novel DMD method to objectively characterize left ventricular (LV) flow in healthy volunteers and patients with dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM). Our approach is based on assessing temporal evolution dependent mode structures from two-dimensional velocity fields, obtained experimentally using echocardiographic color Doppler velocimetry, and defined with a common unit normal moving LV coordinate system. Using the mode structures as a basis, we reconstruct the flow field, determine the key contributing modes, and obtain a reduce order model. Using 20 healthy volunteers, 20 DCM patients and 20 HCM patients, our results show quantitative and qualitative differences between healthy and in the DCM and HCM patients. This study suggests that temporal evolution dependent modes can be used as bio-markers to asses in-vivo LV flow.

  9. [The thickness/radius ratio (h/r) of the left ventricle in pure mitral insufficiency].

    PubMed

    Guadalajara, J F; Alexánderson, E; Monobe, F; Nieto, S; Huerta, D

    1992-01-01

    We studied 11 patients with severe mitral regurgitation (MR). With 2-D echocardiogram we could obtain the septal and posterior wall thickness, left ventricular internal dimensions and ventricular function. With parasternal short axis view we calculate the h/r ratio (left ventricular thickness/radius). The results were compared with normal values: we found important left atrial and ventricle dilatation with significative difference from the normal values (P < 0.001), the diastolic and systolic h/r ratio was significative lower than the normal values (P < 0.005): the systolic wall stress was significative higher in relation to normal values (P < 0.001). We conclude that patients with severe (MR) initially have an important ventricular dilatation but no hypertrophy despite volume overload. The possible explanation is that in early stages of the disease, the afterload of the left ventricle is low and does not trigger the development of hypertrophy. The hypertrophy appears only when the systolic stress is high secondary to myocardial failure. The excessive dilatation of the left ventricle probably damages the myocardial fibers by excessive stretch. This mechanism probably explains the poor late surgical evolution of patients with mitral prosthesis. This we propose that the optimal surgical timing for such patients is when the systolic wall stress elevates over the normal limits, because this is an early sign of myocardial failure.

  10. [Pseudoaneurysm of the left ventricle in young patients: A propos of three cases].

    PubMed

    Ndiaye, M B; Ba, F G; Bodian, M; Diao, M; Kane, A D; Sarr, S A; Mbaye, A; Dia, M M; Jobe, M; Sarr, M; Kane, A; Ba, S A

    2015-09-01

    Pseudoaneurysm of the left ventricle is a rare late complication of myocardial infarction. So-called non-coronary forms have been described in young people. In this context, we report three cases. Mr. M.B., aged 20, consulted for chest pain associated with palpitations. Cardiovascular examination found a pulsatile, expanding precordial bulging and a mesocardiac systolo-diastolic murmur. We noted a sinus rhythm with ventricular extrasystoles on ECG. The chest radiograph showed cardiomegaly and aneurysmal deformation of the left lower heart border. Doppler echocardiography showed a large left ventricular apical pseudoaneurysm. Mrs. O.B., aged 23, was admitted for biventricular heart failure and in whom the examination found a systolic murmur in the apical area. ECG showed a regular sinus tachycardia, left atrial and ventricular hypertrophy. The chest radiograph showed cardiomegaly and aneurysmal deformation of left middle and lower heart borders. Doppler echocardiography showed a large left ventricular apical pseudoaneurysm. Mr. I.S., aged 24, admitted for the management of congestive heart failure. The patient had non-specific laboratory inflammatory signs, a sinus tachycardia and extrasystoles on the ECG. Chest radiography showed a discontinuation at the posterior arch of the sixth rib, a cardiomegaly and a neurismal dilatation of the left lower heart border. Doppler echocardiography showed a large apical pseudoaneurysm of the left ventricle. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  11. Persistent organic pollutants and abnormal geometry of the left ventricle in the elderly.

    PubMed

    Sjöberg Lind, Ylva; Lind, Lars; Salihovic, Samira; van Bavel, Bert; Lind, P Monica

    2013-08-01

    Established risk factors for left ventricular hypertrophy (LVH) are hypertension, diabetes, and obesity. However, as these risk factors explain only part of the variation in left ventricular mass, we investigated whether persistent organic pollutants (POPs) might also play a role in LVH, because exposure to polychlorinated biphenyl 126 induced cardiac growth in rats. In the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS), left ventricular mass index (LVMI), relative wall thickness (RWT), and geometric groups of LVH, were determined by echocardiography and 21 POPs were measured by high-resolution chromatography coupled to high-resolution mass spectrometry (HRGC/HRMS) in 1016 individuals aged 70 years. All individuals with a history of myocardial infarction were excluded from analysis (n = 72). Several of the POPs were related to abnormal left ventricular geometry before adjustment for established risk factors, but lost in significance following adjustment. However, the pesticide hexachlorobenzene (HCB) levels were significantly related to RWT, and concentric left ventricular remodeling, also following adjustment for sex, blood pressure, antihypertensive treatment, diabetes, and BMI (P <0.0001). In this cross-sectional study, circulating levels of HCB were related to increased wall thickness of the left ventricle and concentric left ventricular remodeling, independently of LVH risk factors, suggesting a role of this environmental contaminant in abnormal growth of the left ventricle.

  12. Iatrogenic Perforation of the Left Ventricle during Insertion of a Chest Drain

    PubMed Central

    Kim, Dongmin; Lim, Seong-Hoon

    2013-01-01

    Chest draining is a common procedure for treating pleural effusion. Perforation of the heart is a rare often fatal complication of chest drain insertion. We report a case of a 76-year-old female patient suffering from congestive heart failure. At presentation, unilateral opacity of the left chest observed on a chest X-ray was interpreted as massive pleural effusion, so an attempt was made to drain the left pleural space. Malposition of the chest drain was suspected because blood was draining in a pulsatile way from the catheter. Computed tomography revealed perforation of the left ventricle. Mini-thoracotomy was performed and the drain extracted successfully. PMID:23772413

  13. Finite elements of nonlinear continua.

    NASA Technical Reports Server (NTRS)

    Oden, J. T.

    1972-01-01

    The finite element method is extended to a broad class of practical nonlinear problems, treating both theory and applications from a general and unifying point of view. The thermomechanical principles of continuous media and the properties of the finite element method are outlined, and are brought together to produce discrete physical models of nonlinear continua. The mathematical properties of the models are analyzed, and the numerical solution of the equations governing the discrete models is examined. The application of the models to nonlinear problems in finite elasticity, viscoelasticity, heat conduction, and thermoviscoelasticity is discussed. Other specific topics include the topological properties of finite element models, applications to linear and nonlinear boundary value problems, convergence, continuum thermodynamics, finite elasticity, solutions to nonlinear partial differential equations, and discrete models of the nonlinear thermomechanical behavior of dissipative media.

  14. Second order tensor finite element

    NASA Technical Reports Server (NTRS)

    Oden, J. Tinsley; Fly, J.; Berry, C.; Tworzydlo, W.; Vadaketh, S.; Bass, J.

    1990-01-01

    The results of a research and software development effort are presented for the finite element modeling of the static and dynamic behavior of anisotropic materials, with emphasis on single crystal alloys. Various versions of two dimensional and three dimensional hybrid finite elements were implemented and compared with displacement-based elements. Both static and dynamic cases are considered. The hybrid elements developed in the project were incorporated into the SPAR finite element code. In an extension of the first phase of the project, optimization of experimental tests for anisotropic materials was addressed. In particular, the problem of calculating material properties from tensile tests and of calculating stresses from strain measurements were considered. For both cases, numerical procedures and software for the optimization of strain gauge and material axes orientation were developed.

  15. Finite elements of nonlinear continua.

    NASA Technical Reports Server (NTRS)

    Oden, J. T.

    1972-01-01

    The finite element method is extended to a broad class of practical nonlinear problems, treating both theory and applications from a general and unifying point of view. The thermomechanical principles of continuous media and the properties of the finite element method are outlined, and are brought together to produce discrete physical models of nonlinear continua. The mathematical properties of the models are analyzed, and the numerical solution of the equations governing the discrete models is examined. The application of the models to nonlinear problems in finite elasticity, viscoelasticity, heat conduction, and thermoviscoelasticity is discussed. Other specific topics include the topological properties of finite element models, applications to linear and nonlinear boundary value problems, convergence, continuum thermodynamics, finite elasticity, solutions to nonlinear partial differential equations, and discrete models of the nonlinear thermomechanical behavior of dissipative media.

  16. Finite elements: Theory and application

    NASA Technical Reports Server (NTRS)

    Dwoyer, D. L. (Editor); Hussaini, M. Y. (Editor); Voigt, R. G. (Editor)

    1988-01-01

    Recent advances in FEM techniques and applications are discussed in reviews and reports presented at the ICASE/LaRC workshop held in Hampton, VA in July 1986. Topics addressed include FEM approaches for partial differential equations, mixed FEMs, singular FEMs, FEMs for hyperbolic systems, iterative methods for elliptic finite-element equations on general meshes, mathematical aspects of FEMS for incompressible viscous flows, and gradient weighted moving finite elements in two dimensions. Consideration is given to adaptive flux-corrected FEM transport techniques for CFD, mixed and singular finite elements and the field BEM, p and h-p versions of the FEM, transient analysis methods in computational dynamics, and FEMs for integrated flow/thermal/structural analysis.

  17. Finite elements: Theory and application

    NASA Technical Reports Server (NTRS)

    Dwoyer, D. L. (Editor); Hussaini, M. Y. (Editor); Voigt, R. G. (Editor)

    1988-01-01

    Recent advances in FEM techniques and applications are discussed in reviews and reports presented at the ICASE/LaRC workshop held in Hampton, VA in July 1986. Topics addressed include FEM approaches for partial differential equations, mixed FEMs, singular FEMs, FEMs for hyperbolic systems, iterative methods for elliptic finite-element equations on general meshes, mathematical aspects of FEMS for incompressible viscous flows, and gradient weighted moving finite elements in two dimensions. Consideration is given to adaptive flux-corrected FEM transport techniques for CFD, mixed and singular finite elements and the field BEM, p and h-p versions of the FEM, transient analysis methods in computational dynamics, and FEMs for integrated flow/thermal/structural analysis.

  18. Acclimatization to chronic hypobaric hypoxia is associated with a differential transcriptional profile between the right and left ventricle.

    PubMed

    Adrogue, Julia V; Sharma, Saumya; Ngumbela, Kholiswa; Essop, M Faadiel; Taegtmeyer, Heinrich

    2005-10-01

    Acute hypobaric hypoxia induces a transient reactivation of the fetal-metabolic gene program in the rat heart. Although chronic hypobaric hypoxia causes alterations in metabolism and cardiac function, little is known about the transcriptional profile associated with acclimatization to chronic hypoxia. Because in chronic hypoxia only the right ventricle is exposed to pressure overload (pulmonary hypertension), we hypothesized that chronic hypobaric hypoxia induces a differential transcriptional profile in the right and left ventricle. Male Wistar rats were exposed to a hypobaric environment (11% O2) for 4, 10, and 12 weeks. Right and left ventricular tissue was isolated for histology and candidate gene expression. Chronic hypobaric hypoxia induced right ventricular hypertrophy without fibrosis. In the right ventricle, changes in metabolic gene expression suggested a downregulation of fatty acid metabolism and an increase in glucose metabolism, while left ventricular metabolic gene expression suggested restoration of fatty acid metabolism. While myosin heavy chain isoform transcript levels in the right ventricle indicated a progressive reactivation of the fetal iso-gene pattern, there was normalization of myosin iso-gene expression in the left ventricle. Similarly, sarcoendoplasmic reticulum ATPase 2a (SERCA2a) transcript levels in the right ventricle decreased by 12 weeks of chronic hypoxia exposure, whereas, left ventricular SERCA2a expression was unchanged. In conclusion, acclimatization to chronic hypobaric hypoxia induced a differential transcriptional response between the right and left ventricle. We speculate that reactivation of the fetal-metabolic program in the right ventricle is adaptive to pressure overload.

  19. Electrical analogy of diastolic pressure difference between left atrium and ventricle.

    PubMed

    Haruyama, S; Mori, H; Wan, L M; Shinozaki, Y; Sakamoto, H; Okino, H

    1994-07-01

    We proposed a mathematical model to describe the early filling process of the left ventricle and applied the model to in vivo experiments. The solution of a second-order differential equation indicated that the pressure difference between the left atrium and ventricle during ventricular filling (PD) could be explained by a transient response, i.e. decremental oscillation, in an LCR circuit. Thereafter, we analysed the sequence of PD during vagal stimulation with two catheter-tip manometers in 12 anaesthetised dogs and evaluated changes in the parameters of the system under various haemodynamic conditions. The values of omega n and zeta were quite stable among beats within an episode of vagal stimulation, between episodes and even among dogs, despite the changes in haemodynamic variables. Pericardiotomy and partial discommunication of the mitral valve with the left ventricular free wall by cutting the mitral chordal tendons decreased omega n and increased zeta, mainly because of the increase in CLV. Occlusion of the coronary vascular beds with large numbers of microspheres increased omega n and decreased zeta, mainly because of the decrease in CLV. Mitral obstruction with an inflated balloon (increase in R) abolished the oscillatory changes and produced an exponential decay sequence of PD. In conclusion, both the logical and experimental approaches indicated that the sequence of PD could be considered as decremental oscillation in the LCR circuit and the parameters omega n and zeta could be good indices of the diastolic property of the left ventricle.

  20. Parallel, Implicit, Finite Element Solver

    NASA Astrophysics Data System (ADS)

    Lowrie, Weston; Shumlak, Uri; Meier, Eric; Marklin, George

    2007-11-01

    A parallel, implicit, finite element solver is described for solutions to the ideal MHD equations and the Pseudo-1D Euler equations. The solver uses the conservative flux source form of the equations. This helps simplify the discretization of the finite element method by keeping the specification of the physics separate. An implicit time advance is used to allow sufficiently large time steps. The Portable Extensible Toolkit for Scientific Computation (PETSc) is implemented for parallel matrix solvers and parallel data structures. Results for several test cases are described as well as accuracy of the method.

  1. Obstructive left heart disease in neonates with a "borderline" left ventricle: diagnostic challenges to choosing the best outcome.

    PubMed

    Tuo, Giulia; Khambadkone, Sachin; Tann, Oliver; Kostolny, Martin; Derrick, Graham; Tsang, Victor; Sullivan, Ian; Marek, Jan

    2013-10-01

    In most newborns with left heart obstruction, the choice between a single-ventricle or biventricular management pathway is clear. However, in some neonates with a "borderline" left ventricle, this decision is difficult. Existing criteria do not reliably identify neonates who will have a good long-term outlook after biventricular repair (BVR). The objective of this study was prospective assessment of the outcome after BVR for newborns in whom the left ventricle (LV) was considered "borderline" by an expert group. This study was a prospective follow-up evaluation of neonates with obstructive left heart disease related to a "borderline" LV who underwent biventricular management between January 2005 and April 2011. Of 154 neonates who required intervention for left heart obstruction, 13 (7.8 %) met the echocardiographic (echo) inclusion criteria. At the first and last echo, the z-scores were respectively -1.76 ± 1.37 and -0.66 ± 1.47 (p = 0.013) for the mitral valve, -1.02 ± 1.57 and -0.23 ± 1.78 (p = 0.056) for the aortic valve, and 13.77 ± 5.8 and 20.85 ± 8.9 ml/m(2) (p = 0.006) for the LV end-diastolic volume. At this writing, all 12 survivors are clinically well. However, LV diastolic dysfunction and pulmonary artery hypertension was present in 5 (36 %) of 12 patients. Endocardial fibroelastosis (EFE) was detected in five patients at the last follow-up echo, but only in two patients preoperatively. Cardiac magnetic resonance imaging did not confirm EFE in any of assessed patients. The study authors could not reliably predict the outcome after BVR for neonates with left heart obstruction and a "borderline" LV. The presence of EFE with consequent diastolic dysfunction is more important than LV volume in determining the outcome. Prospective identification of EFE remains challenging.

  2. Element-topology-independent preconditioners for parallel finite element computations

    NASA Technical Reports Server (NTRS)

    Park, K. C.; Alexander, Scott

    1992-01-01

    A family of preconditioners for the solution of finite element equations are presented, which are element-topology independent and thus can be applicable to element order-free parallel computations. A key feature of the present preconditioners is the repeated use of element connectivity matrices and their left and right inverses. The properties and performance of the present preconditioners are demonstrated via beam and two-dimensional finite element matrices for implicit time integration computations.

  3. Element-topology-independent preconditioners for parallel finite element computations

    NASA Technical Reports Server (NTRS)

    Park, K. C.; Alexander, Scott

    1992-01-01

    A family of preconditioners for the solution of finite element equations are presented, which are element-topology independent and thus can be applicable to element order-free parallel computations. A key feature of the present preconditioners is the repeated use of element connectivity matrices and their left and right inverses. The properties and performance of the present preconditioners are demonstrated via beam and two-dimensional finite element matrices for implicit time integration computations.

  4. Transcatheter closure of left ventricle to right atrial communication using cera duct occluder.

    PubMed

    Ganesan, Gnanavelu; Paul, G Justin; Mahadevan, Vaikom S

    Left ventricle-right atrial communication could be congenital (Gerbode defect) or acquired as a complication of surgery or infective endocarditis and leads to volume overloading of pulmonary circulation. Two types, direct and indirect types are known depending on the involvement of septal tricuspid leaflet. Transcatheter closure of this defect is feasible and appears an attractive alternative to surgical management. Various devices like Amplatzer duct occluder I, II, Muscular ventricular septal defect device etc. have been used to close this defect. We report two patients, a preteen boy with direct left ventricle-right atrial communication as post operative complication and an adult female with indirect communication who underwent transcatheter closure with Cera duct occluder (Lifetech Scientific (Shenzhen), China). Copyright © 2017. Published by Elsevier B.V.

  5. [Withdrawal syndrome complicated with heart left ventricle dysfunction in young woman addicted to alcohol].

    PubMed

    Gawlikowski, Tomasz; Biedroń, Witold; Hubalewska-Dydejczyk, Alicja; Pach, Dorota

    2007-01-01

    A case of 23-years old woman, addicted to alcohol and affected by depression, with functional heart disturbances is described. The heart left ventricle dysfunction developed after alcohol withdrawal. In ECG leads (V2-V6, I, II, aVL) symmetrical, negative T waves were present. Echocardio graphy revealed decreased left ventricle ejection fraction (LVEF=35%) and local abnormal contractility. The cardiomyocytes necrosis markers (CK-MB, troponin I) were negative. After several days the improvement of the heart function was observed (LEVF= 56%, improving of myocardium regional contractility). The rest scintigraphy of the heart (99mTc-MIBI GSPECT) was performed and its results corresponded with echocardiography revelations. The ECG changes improved during three weeks hospitalization, but were not normal on discharge.

  6. Inotropic changes in the left ventricle: the effect of changes in heart rate, aortic pressure and end-diastolic pressure

    PubMed Central

    Furnival, C. M.; Linden, R. J.; Snow, H. M.

    1970-01-01

    1. Under conditions where heart rate, mean aortic pressure and enddiastolic pressure in the left ventricle are held constant, the intravenous infusion of isoprenaline is accompanied by large changes in dP/dt max in the left ventricle. 2. Under similar conditions, during stepwise increments in the rate of infusion of isoprenaline the changes in dP/dt max (measured at a constant paced heart rate) were proportional to changes in the free (intrinsic) heart rate. It is concluded that dP/dt max is a quantitative index of inotropic changes in the left ventricle. 3. In comparison to dP/dt max, three other variables which have been used to indicate inotropic changes in the heart (peak pressure in the left ventricle, duration of systole and stroke work at constant end-diastolic pressure), were shown to be unreliable indices of inotropic changes. 4. Using dP/dt max to indicate inotropic changes, alteration in the heart rate while mean aortic pressure and end-diastolic pressure in the left ventricle were held constant, and in mean aortic pressure while heart rate ane end-diastolic pressure in the left ventricle were held constant, were each shown to be accompanied by small inotropic changes in the heart. 5. Under similar conditions, changes in end-diastolic pressure in the left ventricle alone were not accompanied by inotropic changes as indicated by dP/dt max. PMID:5501006

  7. Idiopathic dilated cardiomyopathy: computerized anatomic study of relashionship between septal and free left ventricle wall

    PubMed Central

    Juliani, Paulo Sérgio; da Costa, Éder França; Correia, Aristides Tadeu; Monteiro, Rosangela; Jatene, Fabio Biscegli

    2014-01-01

    Introduction A feature of dilated cardiomyopathy is the deformation of ventricular cavity, which contributes to systolic dysfunction. Few studies have evaluated this deformation bearing in mind ventricular regions and segments of the ventricle, which could reveal important details of the remodeling process, supporting a better understanding of its role in functional impairment and the development of new therapeutic strategies. Objective To evaluate if, in basal, equatorial and apical regions, increased internal transverse perimeter of left ventricle in idiopathic dilated cardiomyopathy occurs proportionally between the septal and non-septal segment. Methods We performed an anatomical study with 28 adult hearts from human cadavers. One group consisted of 18 hearts with idiopathic dilated cardiomyopathy and another group with 10 normal hearts. After lamination and left ventricle digital image capture, in three different regions (base, equator and apex), the transversal internal perimeter of left ventricle was divided into two segments: septal and not septal. These segments were measured by proper software. It was established an index of proportionality between these segments, called septal and non-septal segment index. Then we determined whether this index was the same in both groups. Results Among patients with normal hearts and idiopathic dilated cardiomyopathy, the index of proportionality between the two segments (septal and non-septal) showed no significant difference in the three regions analyzed. The comparison results of the indices NSS/SS among normal and enlarged hearts were respectively: in base 1.99 versus 1.86 (P=0.46), in equator 2.22 versus 2.18 (P=0.79) and in apex 2.96 versus 3.56 (P=0.11). Conclusion In the idiopathic dilated cardiomyopathy, the transversal dilatation of left ventricular internal perimeter occurs proportionally between the segments corresponding to the septum and free wall at the basal, equatorial and apical regions of this chamber

  8. Finite element shell instability analysis

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Formulation procedures and the associated computer program for finite element thin shell instability analysis are discussed. Data cover: (1) formulation of basic element relationships, (2) construction of solution algorithms on both the conceptual and algorithmic levels, and (3) conduction of numerical analyses to verify the accuracy and efficiency of the theory and related programs therein are described.

  9. Computational modeling and analysis for left ventricle motion using CT/Echo image fusion

    NASA Astrophysics Data System (ADS)

    Kim, Ji-Yeon; Kang, Nahyup; Lee, Hyoung-Euk; Kim, James D. K.

    2014-03-01

    In order to diagnose heart disease such as myocardial infarction, 2D strain through the speckle tracking echocardiography (STE) or the tagged MRI is often used. However out-of-plane strain measurement using STE or tagged MRI is inaccurate. Therefore, strain for whole organ which are analyzed by simulation of 3D cardiac model can be applied in clinical diagnosis. To simulate cardiac contraction in a cycle, cardiac physical properties should be reflected in cardiac model. The myocardial wall in left ventricle is represented as a transversely orthotropic hyperelastic material, with the fiber orientation varying sequentially from the epicardial surface, through about 0° at the midwall, to the endocardial surface. A time-varying elastance model is simulated to contract myocardial fiber, and physiological intraventricular systolic pressure curves are employed for the cardiac dynamics simulation in a cycle. And an exact description of the cardiac motion should be acquired in order that essential boundary conditions for cardiac simulation are obtained effectively. Real time cardiac motion can be acquired by using echocardiography and exact cardiac geometrical 3D model can be reconstructed using 3D CT data. In this research, image fusion technology from CT and echocardiography is employed in order to consider patient-specific left ventricle movement. Finally, longitudinal strain from speckle tracking echocardiography which is known to fit actual left ventricle deformation relatively well is used to verify these results.

  10. Soy milk versus simvastatin for preventing atherosclerosis and left ventricle remodeling in LDL receptor knockout mice.

    PubMed

    Santos, L; Davel, A P; Almeida, T I R; Almeida, M R; Soares, E A; Fernandes, G J M; Magalhães, S F; Barauna, V G; Garcia, J A D

    2017-02-20

    Functional food intake has been highlighted as a strategy for the prevention of cardiovascular diseases by reducing risk factors. In this study, we compared the effects of oral treatment with soy milk and simvastatin on dyslipidemia, left ventricle remodeling and atherosclerotic lesion of LDL receptor knockout mice (LDLr-/-) fed a hyperlipidic diet. Forty 3-month old male LDLr-/- mice were distributed into four groups: control group (C), in which animals received standard diet; HL group, in which animals were fed a hyperlipidic diet; HL+SM or HL+S groups, in which animals were submitted to a hyperlipidic diet plus soy milk or simvastatin, respectively. After 60 days, both soy milk and simvastatin treatment prevented dyslipidemia, atherosclerotic lesion progression and left ventricle hypertrophy in LDLr-/- mice. These beneficial effects of soy milk and simvastatin were associated with reduced oxidative stress and inflammatory state in the heart and aorta caused by the hyperlipidic diet. Treatment with soy milk was more effective in preventing HDLc reduction and triacylglycerol and VLDLc increase. On the other hand, simvastatin was more effective in preventing an increase in total cholesterol, LDLc and superoxide production in aorta, as well as CD40L both in aorta and left ventricle of LDLr-/-. In conclusion, our results suggest a cardioprotective effect of soy milk in LDLr-/- mice comparable to the well-known effects of simvastatin.

  11. Soy milk versus simvastatin for preventing atherosclerosis and left ventricle remodeling in LDL receptor knockout mice

    PubMed Central

    Santos, L.; Davel, A.P.; Almeida, T.I.R.; Almeida, M.R.; Soares, E.A.; Fernandes, G.J.M.; Magalhães, S.F.; Barauna, V.G.; Garcia, J.A.D.

    2017-01-01

    Functional food intake has been highlighted as a strategy for the prevention of cardiovascular diseases by reducing risk factors. In this study, we compared the effects of oral treatment with soy milk and simvastatin on dyslipidemia, left ventricle remodeling and atherosclerotic lesion of LDL receptor knockout mice (LDLr-/-) fed a hyperlipidic diet. Forty 3-month old male LDLr-/- mice were distributed into four groups: control group (C), in which animals received standard diet; HL group, in which animals were fed a hyperlipidic diet; HL+SM or HL+S groups, in which animals were submitted to a hyperlipidic diet plus soy milk or simvastatin, respectively. After 60 days, both soy milk and simvastatin treatment prevented dyslipidemia, atherosclerotic lesion progression and left ventricle hypertrophy in LDLr-/- mice. These beneficial effects of soy milk and simvastatin were associated with reduced oxidative stress and inflammatory state in the heart and aorta caused by the hyperlipidic diet. Treatment with soy milk was more effective in preventing HDLc reduction and triacylglycerol and VLDLc increase. On the other hand, simvastatin was more effective in preventing an increase in total cholesterol, LDLc and superoxide production in aorta, as well as CD40L both in aorta and left ventricle of LDLr-/-. In conclusion, our results suggest a cardioprotective effect of soy milk in LDLr-/- mice comparable to the well-known effects of simvastatin. PMID:28225891

  12. Complex blood flow patterns in an idealized left ventricle: A numerical study

    NASA Astrophysics Data System (ADS)

    Tagliabue, Anna; Dedè, Luca; Quarteroni, Alfio

    2017-09-01

    In this paper, we study the blood flow dynamics in a three-dimensional (3D) idealized left ventricle of the human heart whose deformation is driven by muscle contraction and relaxation in coordination with the action of the mitral and aortic valves. We propose a simplified but realistic mathematical treatment of the valves function based on mixed time-varying boundary conditions (BCs) for the Navier-Stokes equations modeling the flow. These switchings in time BCs, from natural to essential and vice versa, model either the open or the closed configurations of the valves. At the numerical level, these BCs are enforced by means of the extended Nitsche's method (Tagliabue et al., Int. J. Numer. Methods Fluids, 2017). Numerical results for the 3D idealized left ventricle obtained by means of Isogeometric Analysis are presented, discussed in terms of both instantaneous and phase-averaged quantities of interest and validated against those available in the literature, both experimental and computational. The complex blood flow patterns are analysed to describe the characteristic fluid properties, to show the transitional nature of the flow, and to highlight its main features inside the left ventricle. The sensitivity of the intraventricular flow patterns to the mitral valve properties is also investigated.

  13. Effect of trabeculae and papillary muscles on the hemodynamics of the left ventricle

    NASA Astrophysics Data System (ADS)

    Vedula, Vijay; Seo, Jung-Hee; Lardo, Albert C.; Mittal, Rajat

    2016-04-01

    The impact of surface trabeculae and papillary muscles on the hemodynamics of the left ventricle (LV) is investigated using numerical simulations. Simulations of ventricular flow are conducted for two different models of the LV derived from high-resolution cardiac computed tomography (CT) scans using an immersed boundary method-based flow solver. One model comprises a trabeculated left ventricle (TLV) that includes both trabeculae and papillary muscles, while the second model has a smooth left ventricle that is devoid of any of these surface features. Results indicate that the trabeculae and papillary muscles significantly disrupt the vortices that develop during early filling in the TLV model. Large recirculation zones are found to form in the wake of the papillary muscles; these zones enhance the blockage provided by the papillary muscles and create a path for the mitral jet to penetrate deeper into the ventricular apex during diastole. During systole, the trabeculae enhance the apical washout by `squeezing' the flow from the apical region. Finally, the trabeculae enhance viscous dissipation rate of the ventricular flow, but this effect is not significant in the overall power budget.

  14. Spatial heterogeneity of four-dimensional relative pressure fields in the human left ventricle.

    PubMed

    Eriksson, Jonatan; Bolger, Ann F; Carlhäll, Carl-Johan; Ebbers, Tino

    2015-12-01

    To assess the spatial heterogeneity of the four-dimensional (4D) relative pressure fields in the healthy human left ventricle (LV) and provide reference data for normal LV relative pressure. Twelve healthy subjects underwent a cardiac MRI examination where 4D flow and morphological data were acquired. The latter data were segmented and used to define the borders of the LV for computation of relative pressure fields using the pressure Poisson equation. The LV lumen was divided into 17 pie-shaped segments. In the normal left ventricle, the relative pressure in the apical segments was significantly higher relative to the basal segments (P < 0.0005) along both the anteroseptal and inferolateral sides after the peaks of early (E-wave) and late (A-wave) diastolic filling. The basal anteroseptal segment showed significantly lower median pressure than the opposite basal inferolateral segment during both E-wave (P < 0.0005) and A-wave (P = 0.0024). Relative pressure in the left ventricle is heterogeneous. During diastole, the main pressure differences in the LV occur along the basal-apical axis. However, pressure differences were also found in the short axis direction and may reflect important aspects of atrioventricular coupling. Additionally, this study provides reference data on LV pressure dynamics for a group of healthy subjects. © 2014 Wiley Periodicals, Inc.

  15. [Diastolic dysfunction of left ventricle in psoriatic patients with concomitant opisthorchiasis before and after antihelminthic therapy].

    PubMed

    Khardikova, S A; Berendeeva, E P; Kaliuzhin, V V; Beloborodova, E I

    2009-01-01

    The aim of the study was to evaluate left ventricular diastolic function in psoriatic patients with chronic opisthrochosis (CO) before and after antihelminthic therapy. It included 75 patients with psoriasis and CO, 50 with psoriasis alone, 50 with CO, and 20 healthy subjects. All patients underwent standard echocardiographic examination in the M-, B-, and Doppler mode. The study revealed impaired active relaxation of the left ventricle manifest as increased isovolumic relaxation time more pronounced in patients with concurrent CO and psoriasis than in those with psoriasis alone. Antihelminthic therapy did not cause deterioration of the diastolic function in these patients and should be recommended in case of combined pathology.

  16. [Air Bubble in the Left Ventricle due to Computed Tomography Guided Lung Needle Biopsy].

    PubMed

    Matsuda, Eisuke; Yoshida, Kumiko; Yoshiyama, Koichi; Hayashi, Tatsuro; Tanaka, Toshiki; Tao, Hiroyuki; Okabe, Kazunori

    2015-11-01

    Computed tomography (CT) guided lung biopsy is a useful examination in diagnosing pulmonary diseases, but the complications such as pneumothorax or pulmonary hemorrhage can not be ignored. Among them, air embolization is a severe complication, although it is infrequently encountered. Forty two-year-old man admitted to our department for the examination of left lung tumor. CT guided lung biopsy was performed. After examination, the patient showed disturbance in cardiac function, which recovered in several minutes. Chest CT revealed air bubble in the left ventricle. After 2-hours head down position followed by bed rest, air bubble is confirmed to be dissappeared by CT.

  17. A robust automated left ventricle region of interest localization technique using a cardiac cine MRI atlas

    NASA Astrophysics Data System (ADS)

    Ben-Zikri, Yehuda Kfir; Linte, Cristian A.

    2016-03-01

    Region of interest detection is a precursor to many medical image processing and analysis applications, including segmentation, registration and other image manipulation techniques. The optimal region of interest is often selected manually, based on empirical knowledge and features of the image dataset. However, if inconsistently identified, the selected region of interest may greatly affect the subsequent image analysis or interpretation steps, in turn leading to incomplete assessment during computer-aided diagnosis or incomplete visualization or identification of the surgical targets, if employed in the context of pre-procedural planning or image-guided interventions. Therefore, the need for robust, accurate and computationally efficient region of interest localization techniques is prevalent in many modern computer-assisted diagnosis and therapy applications. Here we propose a fully automated, robust, a priori learning-based approach that provides reliable estimates of the left and right ventricle features from cine cardiac MR images. The proposed approach leverages the temporal frame-to-frame motion extracted across a range of short axis left ventricle slice images with small training set generated from les than 10% of the population. This approach is based on histogram of oriented gradients features weighted by local intensities to first identify an initial region of interest depicting the left and right ventricles that exhibits the greatest extent of cardiac motion. This region is correlated with the homologous region that belongs to the training dataset that best matches the test image using feature vector correlation techniques. Lastly, the optimal left ventricle region of interest of the test image is identified based on the correlation of known ground truth segmentations associated with the training dataset deemed closest to the test image. The proposed approach was tested on a population of 100 patient datasets and was validated against the ground truth

  18. [Postero'inferior aneurysm of the left ventricle following myocardial infarction. Diagnosis and surgical treatment].

    PubMed

    Flores Covarrubias, S E; Acoltzin Vidal, C; Nava Lopez, G; Palacios Macedo, X

    1979-01-01

    This is a report of the first four cases of left ventricle aneurysm of the posterior and inferior segments successfully treated surgically in the Hospital de Cardiología y Neumología del Centro Médico Nacional, México D. F., and represent the twelve per cent of all realized aneurysmectomies. The patients were all men with 57 years mean age, and a previous history of posteroinferior myocardial infarction, complicated in three of them with angor and severe ventricle arrythmias; chest X ray in lateral view showed a bump of the posteroinferior border of the cardiac silhouette; the echocardiography increase in the ventricular diameter below the mitral valve; the ventriculography made evident a diastolic bulging with systolic expansion of posterior and inferior segments of the left ventricle and no mitral regurgitation; selective coronary arteriography showed a dominant right pattern with 100 per cent proximal occlusion. Aneurysmectomy was done in all four cases and aortocoronary by-pass in two. The posteromedial papilar muscle was found respected in all cases and in two cases a mural thrombus was detected.

  19. A Reconstruction Method of Blood Flow Velocity in Left Ventricle Using Color Flow Ultrasound

    PubMed Central

    Jang, Jaeseong; Ahn, Chi Young; Jeon, Kiwan; Heo, Jung; Lee, DongHak; Choi, Jung-il

    2015-01-01

    Vortex flow imaging is a relatively new medical imaging method for the dynamic visualization of intracardiac blood flow, a potentially useful index of cardiac dysfunction. A reconstruction method is proposed here to quantify the distribution of blood flow velocity fields inside the left ventricle from color flow images compiled from ultrasound measurements. In this paper, a 2D incompressible Navier-Stokes equation with a mass source term is proposed to utilize the measurable color flow ultrasound data in a plane along with the moving boundary condition. The proposed model reflects out-of-plane blood flows on the imaging plane through the mass source term. The boundary conditions to solve the system of equations are derived from the dimensions of the ventricle extracted from 2D echocardiography data. The performance of the proposed method is evaluated numerically using synthetic flow data acquired from simulating left ventricle flows. The numerical simulations show the feasibility and potential usefulness of the proposed method of reconstructing the intracardiac flow fields. Of particular note is the finding that the mass source term in the proposed model improves the reconstruction performance. PMID:26078773

  20. A Reconstruction Method of Blood Flow Velocity in Left Ventricle Using Color Flow Ultrasound.

    PubMed

    Jang, Jaeseong; Ahn, Chi Young; Jeon, Kiwan; Heo, Jung; Lee, DongHak; Joo, Chulmin; Choi, Jung-il; Seo, Jin Keun

    2015-01-01

    Vortex flow imaging is a relatively new medical imaging method for the dynamic visualization of intracardiac blood flow, a potentially useful index of cardiac dysfunction. A reconstruction method is proposed here to quantify the distribution of blood flow velocity fields inside the left ventricle from color flow images compiled from ultrasound measurements. In this paper, a 2D incompressible Navier-Stokes equation with a mass source term is proposed to utilize the measurable color flow ultrasound data in a plane along with the moving boundary condition. The proposed model reflects out-of-plane blood flows on the imaging plane through the mass source term. The boundary conditions to solve the system of equations are derived from the dimensions of the ventricle extracted from 2D echocardiography data. The performance of the proposed method is evaluated numerically using synthetic flow data acquired from simulating left ventricle flows. The numerical simulations show the feasibility and potential usefulness of the proposed method of reconstructing the intracardiac flow fields. Of particular note is the finding that the mass source term in the proposed model improves the reconstruction performance.

  1. An Endomyocardial Biopsy of the Left Ventricle in an Anorexia Nervosa Patient with Sinus Bradycardia and Left Ventricular Systolic Dysfunction

    PubMed Central

    Takahashi, Satoshi

    2016-01-01

    Anorexia nervosa (AN) is an eating disorder characterized by an abnormally low body weight, an intense fear of gaining weight, and a distorted perception of body weight. AN is a life-threatening condition that significantly increases the risk of death due to cardiac complications, such that at least one-third of all deaths in patients with AN are associated with cardiac causes including sudden death. In many reports, sudden death has been linked to reduced left ventricular function, structural changes, and QT abnormalities. However, the mechanistic details connecting AN to cardiac abnormalities remain unknown. Here we present an endomyocardial biopsy of the left ventricle in a case of AN with a reversible left ventricular systolic dysfunction. PMID:27833764

  2. [Penetrating foreign body in the left ventricle with undetected chronic evolution].

    PubMed

    Moreno-Martínez, Francisco L; Lagomasino Hidalgo, Alvaro L; Chao García, Jean L; Bermúdez Yera, Gustavo; Ibargollín Hernández, Rosendo; Vega Fleites, Luis Felipe; Medrano Plana, Yuri; Castañeda Casarvilla, Luis; Pérez, Guillermo A; Monteagudo Lima, Luis; López-Bernal, Omaida J

    2009-01-01

    Penetrating cardiac trauma constitutes a serious threat for life. Less than the third part of all patients who suffer it arrives at the hospital alive, and half of them die. Most of the penetrating foreign bodies in the heart are metallic, and are frequently caused by firearms and rarely by self-injury. The accidental penetration is uncommon but inadvertent penetration is extremely rare. We present the case of a patient who suffered a closed-chest trauma and did not notice the penetration of a foreign body (copper wire fragment) in the heart. It remained lodged in the left ventricle for more than 3 months. This it is the only case reported in the literature where a strange body: a) crosses the free wall of the right ventricle, the right ventricular cavity, interventricular septum, and the mitral valve apparatus; b) occupies almost all the anteroposterior diameter of the heart, and c) did not produce acute or chronic bleeding.

  3. [Dispersion pattern of saline indicator on canine left ventricle (author's transl)].

    PubMed

    Neto, S G; Mello, A

    1976-01-01

    The cardiac output evaluation is usually realized through indicator dilution techniques and this principle was applied to ventricular volume measurements. However this approach has been criticized by several workers. Based on the recently developed association of indicator dilution method with intraventricular impedance recording to cardiac output determinations, the present investigation was designed to analize the dipersion pattern of saline solution within the ventricle. Three bipolar eletrodes were placed in different positions on the left ventricle in order to record the duration in seconds, for the saline to reach these positions. The detection of the saline was done through conductibility changes at the eletrodes ends. The results indicate a time duration smaller to the indicator dispersion than those of the diastole duration, simultaneously measured.

  4. Kinematic, Dynamic, and Energy Characteristics of Diastolic Flow in the Left Ventricle.

    PubMed

    Khalafvand, Seyed Saeid; Hung, Tin-Kan; Ng, Eddie Yin-Kwee; Zhong, Liang

    2015-01-01

    Blood flow characteristics in the normal left ventricle are studied by using the magnetic resonance imaging, the Navier-Stokes equations, and the work-energy equation. Vortices produced during the mitral valve opening and closing are modeled in a two-dimensional analysis and correlated with temporal variations of the Reynolds number and pressure drop. Low shear stress and net pressures on the mitral valve are obtained for flow acceleration and deceleration. Bernoulli energy flux delivered to blood from ventricular dilation is practically balanced by the energy influx and the rate change of kinetic energy in the ventricle. The rates of work done by shear and energy dissipation are small. The dynamic and energy characteristics of the 2D results are comparable to those of a 3D model.

  5. Kinematic, Dynamic, and Energy Characteristics of Diastolic Flow in the Left Ventricle

    PubMed Central

    Khalafvand, Seyed Saeid; Hung, Tin-Kan; Ng, Eddie Yin-Kwee; Zhong, Liang

    2015-01-01

    Blood flow characteristics in the normal left ventricle are studied by using the magnetic resonance imaging, the Navier-Stokes equations, and the work-energy equation. Vortices produced during the mitral valve opening and closing are modeled in a two-dimensional analysis and correlated with temporal variations of the Reynolds number and pressure drop. Low shear stress and net pressures on the mitral valve are obtained for flow acceleration and deceleration. Bernoulli energy flux delivered to blood from ventricular dilation is practically balanced by the energy influx and the rate change of kinetic energy in the ventricle. The rates of work done by shear and energy dissipation are small. The dynamic and energy characteristics of the 2D results are comparable to those of a 3D model. PMID:26417381

  6. Transcatheter desiccation of the canine left ventricle using radiofrequency energy: a pilot study

    SciTech Connect

    Huang, S.K.; Graham, A.R.; Hoyt, R.H.; Odell, R.C.

    1987-07-01

    Catheter ablation of cardiac tissue by means of direct-current electrical energy is associated with several complications. We assessed the efficacy and safety of closed-chest catheter desiccation of the left ventricular myocardium with microbipolar radiofrequency (RF) energy (750 kHz) in five dogs. The unipolar configuration was used with RF energy delivered between the tip electrode of a standard No. 7F tripolar catheter in the left ventricle and an external patch electrode on the left lateral chest wall. A single application with different RF energy settings (100 J, 200 J, and 300 J) was delivered to three individual endocardial sites of the left ventricle. Ventricular tachycardia or fibrillation was not observed during energy application and 24 hours after ablation, as assessed by a Holter recording. There was no damage to the electrode catheter. Dogs were killed on the fifth day. Pathology showed well-delineated ovoid or round-shaped coagulation necrosis at the ablation sites. Microscopic findings consisted of circumscribed areas of necrosis surrounded by a zone of fibroblastic and mononuclear proliferation. In conclusion, catheter ablation of the ventricular myocardium with RF energy is an apparently safe procedure and can effectively produce discrete areas of injury without destruction of surrounding uninvolved myocardium. This method offers potential clinical utility for catheter ablation of refractory sustained ventricular tachycardia.

  7. Finite Element Analysis of Ventricular Wall Motion and Intra-Ventricular Blood Flow in Heart with Myocardial Infarction

    NASA Astrophysics Data System (ADS)

    Watanabe, Hiroshi; Sugano, Takeshi; Sugiura, Seiryo; Hisada, Toshiaki

    To study the wall motion abnormality and characteristic flow distribution observed in the heart with myocardial infarction, we modified our finite element model of left ventricle and performed simulations at two different phases after the onset of the disease by applying characteristic material property to the infarcted region. The model could not only reproduce the hemodynamic change in myocardial infarction but also give mechanistic insight into the following complicating problems. 1) Stagnation of blood as the cause of clot formation 2) Extra energy wasted for the stretch of infarcted tissue. The effect of compensatory enhancement of the force generation in normal myocardial tissue is also discussed.

  8. Left and Right Ventricle Late Remodeling Following Myocardial Infarction in Rats

    PubMed Central

    Stefanon, Ivanita; Valero-Muñoz, María; Fernandes, Aurélia Araújo; Ribeiro, Rogério Faustino; Rodríguez, Cristina; Miana, Maria; Martínez-González, José; Spalenza, Jessica S.; Lahera, Vicente; Vassallo, Paula F.; Cachofeiro, Victoria

    2013-01-01

    Background The mechanisms involved in cardiac remodeling in left (LV) and right ventricles (RV) after myocardial infarction (MI) are still unclear. We assayed factors involved in collagen turnover in both ventricles following MI in rats either presenting signs of heart failure (pulmonary congestion and increased LVEDP) or not (INF-HF or INF, respectively). Methods MI was induced in male rats by ligation of the left coronary artery. Four weeks after MI gene expression of collagen I, connective tissue growth factor (CTGF), transforming growth factor β (TGF-β) and lysyl oxidase (LOX), metalloproteinase-2 (MMP2) and tissue inhibitor metalloproteinase-2 (TIMP2) as well as cardiac hemodynamic in both ventricles were evaluated. Results Ventricular dilatation, hypertrophy and an increase in interstitial fibrosis and myocyte size were observed in the RV and LV from INF-HF animals, whereas only LV dilatation and fibrosis in RV was present in INF. The LV fibrosis in INF-HF was associated with higher mRNA of collagen I, CTGF, TGF-β and LOX expressions than in INF and SHAM animals, while MMP2/TIMP2 mRNA ratio did not change. RV fibrosis in INF and INF-HF groups was associated with an increase in LOX mRNA and a reduction in MMP2/TIMP2 ratio. CTGF mRNA was increased only in the INF-HF group. Conclusions INF and INF-HF animals presented different patterns of remodeling in both ventricles. In the INF-HF group, fibrosis seems to be consequence of collagen production in LV, and by reductions in collagen degradation in RV of both INF and INF-HF animals. PMID:23741440

  9. Mathematical model of the anatomy and fibre orientation field of the left ventricle of the heart

    PubMed Central

    2013-01-01

    Background One of the main factors affecting propagation of electrical waves and contraction in ventricles of the heart is anisotropy of cardiac tissue. Anisotropy is determined by orientation of myocardial fibres. Determining fibre orientation field and shape of the heart is important for anatomically accurate modelling of electrical and mechanical function of the heart. The aim of this paper is to introduce a theoretical rule-based model for anatomy and fibre orientation of the left ventricle (LV) of the heart and to compare it with experimental data. We suggest explicit analytical formulae that allow us to obtain the left ventricle form and its fibre direction field. The ventricle band concept of cardiac architecture given by Torrent-Guasp is chosen as the model postulate. Methods In our approach, anisotropy of the heart is derived from some general principles. The LV is considered as a set of identical spiral surfaces, each of which can be produced from the other by rotation around one vertical axis. Each spiral surface is filled with non-intersecting curves which represent myocardial fibres. For model verification, we use experimental data on fibre orientation in human and canine hearts. Results LV shape and anisotropy are represented by explicit analytical expressions in a curvilinear 3-D coordinate system. The derived fibre orientation field shows good qualitative agreement with experimental data. The model reveals the most thorough quantitative simulation of fibre angles at the LV middle zone. Conclusions Our analysis shows that the band concept can generate realistic anisotropy of the LV. Our model shows good qualitative agreement between the simulated fibre orientation field and the experimental data on LV anisotropy, and the model can be used for various numerical simulations to study the effects of anisotropy on cardiac excitation and mechanical function. PMID:23773421

  10. Mathematical model of the anatomy and fibre orientation field of the left ventricle of the heart.

    PubMed

    Pravdin, Sergey F; Berdyshev, Vitaly I; Panfilov, Alexander V; Katsnelson, Leonid B; Solovyova, Olga; Markhasin, Vladimir S

    2013-06-18

    One of the main factors affecting propagation of electrical waves and contraction in ventricles of the heart is anisotropy of cardiac tissue. Anisotropy is determined by orientation of myocardial fibres. Determining fibre orientation field and shape of the heart is important for anatomically accurate modelling of electrical and mechanical function of the heart. The aim of this paper is to introduce a theoretical rule-based model for anatomy and fibre orientation of the left ventricle (LV) of the heart and to compare it with experimental data. We suggest explicit analytical formulae that allow us to obtain the left ventricle form and its fibre direction field. The ventricle band concept of cardiac architecture given by Torrent-Guasp is chosen as the model postulate. In our approach, anisotropy of the heart is derived from some general principles. The LV is considered as a set of identical spiral surfaces, each of which can be produced from the other by rotation around one vertical axis. Each spiral surface is filled with non-intersecting curves which represent myocardial fibres.For model verification, we use experimental data on fibre orientation in human and canine hearts. LV shape and anisotropy are represented by explicit analytical expressions in a curvilinear 3-D coordinate system. The derived fibre orientation field shows good qualitative agreement with experimental data. The model reveals the most thorough quantitative simulation of fibre angles at the LV middle zone. Our analysis shows that the band concept can generate realistic anisotropy of the LV. Our model shows good qualitative agreement between the simulated fibre orientation field and the experimental data on LV anisotropy, and the model can be used for various numerical simulations to study the effects of anisotropy on cardiac excitation and mechanical function.

  11. Reflex responses to stimulation of mechanoreceptors in the left ventricle and coronary arteries in anaesthetized dogs.

    PubMed Central

    al-Timman, J K; Drinkhill, M J; Hainsworth, R

    1993-01-01

    1. Previous work has shown that physiological increases in mean aortic root pressure, which change the pressure in both the coronary circulation and the left ventricle, result in reflex vasodilatation. This study was undertaken to attempt to localize the reflexogenic area mainly responsible for the reflex. 2. In anaesthetized, artificially ventilated dogs, cannulae connected to perfusion systems were inserted in the ascending aorta, left ventricular apex and left atrium. This allowed us to change the pressures in: (a) the aortic root including both the coronary arteries and the left ventricle; (b) aortic root and coronary arteries, at constant ventricular pressure; and (c) in the ventricle, with mean (although not pulse) aortic pressure constant. Aortic and carotid baroreceptors were perfused at constant pressure and reflex responses were determined from changes in perfusion pressures (flows constant) to a vascularly isolated hindlimb and to the remainder of the systemic circulation. 3. Combined changes in mean aortic root (coronary arterial) and ventricular systolic pressures consistently resulted in decreases in perfusion pressures. A change in only mean aortic root (coronary arterial) pressure, with ventricular pressure constant, also resulted in decreases in perfusion pressures and these were only a little smaller than those to the combined stimulus. Changes in ventricular systolic pressure resulted in responses averaging only about 30% of those to the combined stimulus. 4. Setting mean aortic root or ventricular systolic pressures at different levels did not affect the responses to changes in pressures in the other region. 5. These results show that physiological increases in pressure in the aortic root and coronary arteries, in the absence of changes in pressure in the left ventricle, cause reflex vasodilatation. The relatively small response occurring when ventricular pressure was changed could be due either to a contribution from ventricular receptors or to

  12. A Large Left Ventricle Myxoma: Presenting with Epigastric Pain and Weight Loss

    PubMed Central

    2016-01-01

    Cardiac myxomas are the most common benign tumors found in the heart. They usually appear in the left atrium. Those originating from the left ventricle (LV) are rare. Although clinical presentation may vary, dyspnea and embolism are the most commonly reported symptoms. In the present case study, a 27-year-old woman with a large myxoma originating from the left ventricular free wall is studied. She had atypical complaints, mainly epigastric discomfort, nausea, vomiting, and anorexia. She was hospitalized for acute abdomen, but subsequent investigations revealed a large myxoma that fully filled the LV and severely compromised the flow of the aortic and mitral valves. After successful emergency tumor resection, all symptoms disappeared. The uncommon presentation caused by these tumors is discussed in this study. PMID:28090362

  13. Lung mass appearing as a dilated left ventricle on Tc-99m tetrofosmin myocardial perfusion scintigraphy.

    PubMed

    Gnanasegaran, Gopinath; Williams, Robert; Mclean, Emma; O' Connell, Rachel; Nunan, Thomas O; O'Doherty, Michael J

    2009-09-01

    Tc-99m tetrofosmin is a common tracer used in myocardial perfusion scintigraphy. Several benign and malignant tumors also take up tetrofosmin. We present a case of a 60-year-old woman with a history of a left lung mass awaiting resection. The patient was referred for a myocardial perfusion scan for preoperative risk assessment. The myocardial perfusion scan revealed a large cavitated lesion mimicking a dilated left ventricle and the CT scan revealed a large mass in the left lung with central necrosis displacing the heart and mediastinum. The patient underwent thoracotomy with resection of the mass and the histology confirmed atypical carcinoid. This case highlights noncardiac uptake of Tc-99m tetrofosmin in an atypical carcinoid.

  14. Choroid plexus cyst of the left lateral ventricle with intermittent blockage of the foramen of Monro, and initial invagination into the III ventricle in a child.

    PubMed

    Parízek, J; Jakubec, J; Hobza, V; Nemecková, J; Cernoch, Z; Sercl, M; Zizka, J; Spacek, J; Nemecek, S; Suba, P

    1998-12-01

    A cyst of the choroid plexus of the left lateral ventricle with intermittent blockage of the foramen of Monro and initially with invagination of the III ventricle in a child is described. In a 6-week-old boy a ventriculoatrial shunt was implanted for correction of an active asymmetrical hydrocephalus of unknown origin. When he was 3 months of age a water-soluble contrast CT ventriculography revealed a noncolloid cyst localised predominantly in the upper portion of the III ventricle. At that time the ventricular catheter obstructed with choroid plexus was removed; new bilateral catheters in a parieto-occipital region were implanted. In the course of the next 4 years, first the atrial catheter had to be extracted and then the peritoneal catheter was changed, in both cases because of obstruction. Periods of normal life alternated with periods of transient and intermittent symptoms of increased intracranial pressure, papilloedema, and myoclonic jerks. Repeated computed tomography (CT) and magnetic resonance imaging (MRI) showed stabilised hydrocephalus with an enlarged left lateral ventricle. When the boy was 16 years old MRI revealed a choroid plexus cyst in the left lateral ventricle 2 cm in diameter, with a ballvalve type of obstruction of the foramen of Monro. CT stereoendoscopic resection of the wall of a large cyst filled with cerebrospinal fluid was performed, and two additional adnexal small cysts were coagulated using the bipolar coagulator, Diomed 25 laser and scissors; the symptoms then regressed, except for superior bilateral altitudinal anopsia. Light and electron microscopy of the cyst wall is reported. The cyst was composed of collagenic connective tissue lined with a basal lamina lacking in epithelial cells. The preoperative and postoperative MRI are presented. Choroid plexus cysts localised in the anterior part of lateral ventricles are very rare, and all reported cases have been in male patients. According to the literature our case is only the third

  15. Infinite Possibilities for the Finite Element.

    ERIC Educational Resources Information Center

    Finlayson, Bruce A.

    1981-01-01

    Describes the uses of finite element methods in solving problems of heat transfer, fluid flow, etc. Suggests that engineers should know the general concepts and be able to apply the principles of finite element methods. (Author/WB)

  16. SUPG Finite Element Simulations of Compressible Flows

    NASA Technical Reports Server (NTRS)

    Kirk, Brnjamin, S.

    2006-01-01

    The Streamline-Upwind Petrov-Galerkin (SUPG) finite element simulations of compressible flows is presented. The topics include: 1) Introduction; 2) SUPG Galerkin Finite Element Methods; 3) Applications; and 4) Bibliography.

  17. Automatic left ventricle detection in echocardiographic images for deformable contour initialization.

    PubMed

    Seng, Cher Hau; Demirli, Ramazan; Amin, Moeness G; Seachrist, Jason L; Bouzerdoum, Abdesselam

    2011-01-01

    The accurate left ventricular boundary detection in echocardiographic images allow cardiologists to study and assess cardiomyopathy in patients. Due to the tedious and time consuming manner of manually tracing the borders, deformable models are generally used for left ventricle segmentations. However, most deformable models require a good initialization, which is usually outlined manually by the user. In this paper, we propose an automated left ventricle detection method for two-dimensional echocardiographic images that could serve as an initialization for deformable models. The proposed approach consists of pre-processing and post-processing stages, coupled with the watershed segmentation. The pre-processing stage enhances the overall contrast and reduces speckle noise, whereas the post-processing enhances the segmented region and avoids the papillary muscles. The performance of the proposed method is evaluated on real data. Experimental results show that it is suitable for automatic contour initialization since no prior assumptions nor human interventions are required. Besides, the computational time taken is also lower compared to an existing method.

  18. Elastic modulus of the human intact left ventricle - Determination and physiological interpretation

    NASA Technical Reports Server (NTRS)

    Ghista, D. N.; Sandler, H.; Vayo, W. H.

    1975-01-01

    The left ventricle (l.v.) is represented as a shell of muscle whose performance is characterized in terms of the chamber pressure and stress/strain in the ventricular wall; the effective elastic modulus of the l.v. relates these performance variables, and hence represents the transfer function of the left ventricular physiological system. A method is presented for indirectly determining the effective modulus E for the left ventricle. The method employs a thick-walled mathematical model of the l.v. having a homogeneous isotropic medium. Instantaneous values of E are determined for subjects with heart diseases of varied etiologies, in order to assess the responses of the l.v. to chronic overloads of pressure and volume. Resulting values for E are used diagnostically to characterize the physiological state of the l.v. Normal values of E, at systole, indicate that the strength of contraction exercised by the l.v. is normal, and hence is an indication of the l.v. having adjusted to the heart disease.

  19. Curve evolution with a dual shape similarity and its application to segmentation of left ventricle

    NASA Astrophysics Data System (ADS)

    Woo, Jonghye; Hong, Byung-Woo; Ramesh, Amit; Germano, Guido; Kuo, C.-C. Jay; Slomka, Piotr

    2009-02-01

    Automated image segmentation has been playing a critical role in medical image analysis. Recentl, Level Set methods have shown an efficacy and efficiency in various imaging modalities. In this paper, we present a novel segmentation approach to jointly delineate the boundaries of epi- and endocardium of the left ventricle on the Magnetic Resonance Imaging (MRI) images in a variational framework using level sets, which is in great demand as a clinical application in cardiology. One strategy to tackle segmentation under undesirable conditions such as subtle boundaries and occlusions is to exploit prior knowledge which is specific to the object to segment, in this case the knowledge about heart anatomy. While most left ventricle segmentation approaches incorporate a shape prior obtained by a training process from an ensemble of examples, we exploit a novel shape constraint using an implicit shape prior knowledge, which assumes shape similarity between epi- and endocardium allowing a variation under the Gaussian distribution. Our approach does not demand a training procedure which is usually subject to the training examples and is also laborious and time-consuming in generating the shape prior. Instead, we model a shape constraint by a statistical distance between the shape of epi- and endocardium employing signed distance functions. We applied this technique to cardiac MRI data with quantitative evaluations performed on 10 subjects. The experimental results show the robustness and effectiveness of our shape constraint within a Mumford-Shah segmentation model in the segmentation of left ventricle from cardiac MRI images in comparison with the manual segmentation results.

  20. Scaling of left ventricle cardiomyocyte ultrastructure across development in the kangaroo Macropus fuliginosus.

    PubMed

    Snelling, Edward P; Taggart, David A; Maloney, Shane K; Farrell, Anthony P; Leigh, Christopher M; Waterhouse, Lyn; Williams, Ruth; Seymour, Roger S

    2015-06-01

    The heart and left ventricle of the marsupial western grey kangaroo Macropus fuliginosus exhibit biphasic allometric growth, whereby a negative shift in the trajectory of cardiac growth occurs at pouch exit. In this study, we used transmission electron microscopy to examine the scaling of left ventricle cardiomyocyte ultrastructure across development in the western grey kangaroo over a 190-fold body mass range (0.355-67.5 kg). The volume-density (%) of myofibrils, mitochondria, sarcoplasmic reticuli and T-tubules increase significantly during in-pouch growth, such that the absolute volume (ml) of these organelles scales with body mass (Mb; kg) with steep hyperallometry: 1.41Mb (1.38), 0.64Mb (1.29), 0.066Mb (1.45) and 0.035Mb (1.87), respectively. Maturation of the left ventricle ultrastructure coincides with pouch vacation, as organelle volume-densities scale independent of body mass across post-pouch development, such that absolute organelle volumes scale in parallel and with relatively shallow hypoallometry: 4.65Mb (0.79), 1.75Mb (0.77), 0.21Mb (0.79) and 0.35Mb (0.79), respectively. The steep hyperallometry of organelle volumes and volume-densities across in-pouch growth is consistent with the improved contractile performance of isolated cardiac muscle during fetal development in placental mammals, and is probably critical in augmenting cardiac output to levels necessary for endothermy and independent locomotion in the young kangaroo as it prepares for pouch exit. The shallow hypoallometry of organelle volumes during post-pouch growth suggests a decrease in relative cardiac requirements as body mass increases in free-roaming kangaroos, which is possibly because the energy required for hopping is independent of speed, and the capacity for energy storage during hopping could increase as the kangaroo grows. © 2015. Published by The Company of Biologists Ltd.

  1. Model-based localization of the left ventricle from cardiac MR scans

    NASA Astrophysics Data System (ADS)

    Gong, Leiguang; Cui, Ting; Kulikowski, Casimir A.; Mezrich, Reuben S.

    1993-07-01

    A new approach for the extraction of the myocardium from MR cardiac scans is presented. Segmentation and recognition of the left ventricle by a sequence of generic image processing operations is carried out in an order determined by a model of domain-specific relational, spatial, and morphological knowledge of the cardiac images. In particular, a new technique for constrained surface deformation by variable morphological dilation is introduced. These methods, incorporated in a prototype system called CARDIAN, have produced encouraging results in initial experiments with MR scans from phantom, dog, and human studies.

  2. Oxygen utilization of the human left ventricle - An indirect method for its evaluation and clinical considerations

    NASA Technical Reports Server (NTRS)

    Ghista, D. N.; Sandler, H.

    1974-01-01

    An analytical method is presented for determining the oxygen consumption rate of the intact heart working (as opposed to empty but beating) human left ventricle. Use is made of experimental recordings obtained for the chamber pressure and the associated dimensions of the LV. LV dimensions are determined by cineangiocardiography, and the chamber pressure is obtained by means of fluid-filled catheters during retrograde or transeptal catheterization. An analytical method incorporating these data is then employed for the evaluation of the LV coronary oxygen consumption in five subjects. Oxygen consumption for these subjects was also obtained by the conventional clinical method in order to evaluate the reliability of the proposed method.

  3. Fat infiltration of left ventricle - a rare cause of sudden cardiac death.

    PubMed

    Kanchan, Tanuj; Acharya, Jenash; Ram, Pradhum; Khadilkar, Urmila N; Rana, Talvinder

    2016-09-01

    Cor adiposum is a rare disorder of the heart, where the normal heart tissue is replaced by fibro-fatty infiltrates. We report one such case of a middle-aged female who was declared dead shortly after a syncopal episode. At autopsy, the pericardium was intact and firmly adhered to the heart. Histopathology revealed fatty infiltrates extending into the left ventricle of the heart. A post-mortem diagnosis of Cor adiposum was made which is an uncommonly reported cause of sudden cardiac death. © The Author(s) 2016.

  4. [The thickness/radius ratio of the left ventricle in aortic stenosis. Prognostic and therapeutic implications].

    PubMed

    Guadalajara, J F; Martínez, C; Huerta, D

    1990-01-01

    Using two-D echocardiography and cardiac catheterization we studied the performance of left ventricle in severe aortic stenosis with normal ventricular function (10 patients), and with heart failure (11 patients). With appropriate hypertrophy increased ventricular function, is found resulting in systolic wall stress normalization. When hypertrophic mechanism is unable to normalize the systolic wall stress; afterload increases with ensuing heart failure (inadequate hypertrophy). Surgical treatment in those cases reduces the afterload and increases de ventricular function. Normalization of systolic wall stress in patients with severe aortic stenosis and heart failure means irreversible myocardial damage.

  5. Homogenous protein programming in the mammalian left and right ventricle free walls.

    PubMed

    Phillips, Darci; Aponte, Angel M; Covian, Raul; Neufeld, Edward; Yu, Zu-Xi; Balaban, Robert S

    2011-11-07

    Despite identical cardiac outputs, the right (RV) and left ventricle (LV) have very different embryological origins and resting workload. These differences suggest that the ventricles have different protein programming with regard to energy metabolism and contractile elements. The objective of this study was to determine the relative RV and LV protein expression levels, with an emphasis on energy metabolism. The RV and LV protein contents of the rabbit and porcine heart were determined with quantitative gel electrophoresis (2D-DIGE), mass spectrometry, and optical spectroscopy techniques. Surprisingly, the expression levels for more than 600 RV and LV proteins detected were similar. This included proteins many different compartments and metabolic pathways. In addition, no isoelectric shifts were detected in 2D-DIGE consistent with no differential posttranslational modifications in these proteins. Analysis of the RV and LV metabolic response to work revealed that the metabolic rate increases much faster with workload in the RV compared with LV. This implies that the generally lower metabolic stress of the RV actually approaches LV metabolic stress at maximum workloads. Thus, identical levels of energy conversion and mechanical elements in the RV and LV may be driven by the performance requirements at maximum workloads. In summary, the ventricles of the heart manage the differences in overall workload by modifying the amounts of cytosol, not its composition. The constant myocyte composition in the LV and RV implies that the ratio of energy metabolism and contractile elements may be optimal for the sustained cardiac contractile activity in the mammalian heart.

  6. Monoamine Oxidase Is Overactivated in Left and Right Ventricles from Ischemic Hearts: An Intriguing Therapeutic Target

    PubMed Central

    Manni, Maria Elena; Borchi, Elisabetta; Bargelli, Valentina

    2016-01-01

    Growing evidence indicates that reactive oxygen species (ROS) may play a key role in human heart failure (HF). Monoamine oxidase (MAO) is emerging as a major ROS source in several cardiomyopathies. However, little is known about MAO activity in human failing heart and its relationship with redox imbalance. Therefore, we measured MAO activity in the left (LV) and in the right (RV) ventricle of human nonfailing (NF) and in end-stage ischemic (IHD) and nonischemic failing hearts. We found that both MAO isoforms (MAO-A/B) significantly increased in terms of activity and expression levels only in IHD ventricles. Catalase and aldehyde dehydrogenase-2 activities (ALDH-2), both implicated in MAO-catalyzed catecholamine catabolism, were significantly elevated in the failing LV, whereas, in the RV, statistical significance was observed only for ALDH-2. Oxidative stress markers levels were significantly increased only in the failing RV. Actin oxidation was significantly elevated in both failing ventricles and related to MAO-A activity and to functional parameters. These data suggest a close association between MAO-A-dependent ROS generation, actin oxidation, and ventricular dysfunction. This latter finding points to a possible pathogenic role of MAO-A in human myocardial failure supporting the idea that MAO-A could be a new therapeutic target in HF. PMID:28044091

  7. Finite element model and identification procedure

    NASA Technical Reports Server (NTRS)

    How, Jonathan P.; Blackwood, Gary; Anderson, Eric; Balmes, Etienne

    1992-01-01

    Viewgraphs on finite element model and identification procedure are presented. Topics covered include: interferometer finite element model; testbed mode shapes; finite element model update; identification procedure; shaker locations; data analysis; modal frequency and damping comparison; computational procedure; fit comparison; residue analysis; typical residues; identification/FEM residual comparison; and pathlength control using isolation mounts.

  8. Peridynamic Multiscale Finite Element Methods

    SciTech Connect

    Costa, Timothy; Bond, Stephen D.; Littlewood, David John; Moore, Stan Gerald

    2015-12-01

    The problem of computing quantum-accurate design-scale solutions to mechanics problems is rich with applications and serves as the background to modern multiscale science research. The prob- lem can be broken into component problems comprised of communicating across adjacent scales, which when strung together create a pipeline for information to travel from quantum scales to design scales. Traditionally, this involves connections between a) quantum electronic structure calculations and molecular dynamics and between b) molecular dynamics and local partial differ- ential equation models at the design scale. The second step, b), is particularly challenging since the appropriate scales of molecular dynamic and local partial differential equation models do not overlap. The peridynamic model for continuum mechanics provides an advantage in this endeavor, as the basic equations of peridynamics are valid at a wide range of scales limiting from the classical partial differential equation models valid at the design scale to the scale of molecular dynamics. In this work we focus on the development of multiscale finite element methods for the peridynamic model, in an effort to create a mathematically consistent channel for microscale information to travel from the upper limits of the molecular dynamics scale to the design scale. In particular, we first develop a Nonlocal Multiscale Finite Element Method which solves the peridynamic model at multiple scales to include microscale information at the coarse-scale. We then consider a method that solves a fine-scale peridynamic model to build element-support basis functions for a coarse- scale local partial differential equation model, called the Mixed Locality Multiscale Finite Element Method. Given decades of research and development into finite element codes for the local partial differential equation models of continuum mechanics there is a strong desire to couple local and nonlocal models to leverage the speed and state of the

  9. Finite element simulation of microindentation

    NASA Astrophysics Data System (ADS)

    Zhuk, D. I.; Isaenkova, M. G.; Perlovich, Yu. A.; Krymskaya, O. A.

    2017-05-01

    Finite element models are created to describe the testing of a material by a Berkovich indenter. The results of calculations by these models are compared to experimental data on indentation of the same material (grade 10 steel). The experimental and calculated data agree well with each other. The developed models for an indenter and the material to be tested are used to find the laws of behavior of a material during indentation. The state of stress in the material under an indenter is studied by various methods. The indentation results are plotted versus the mechanical properties of a material.

  10. Fully-coupled fluid-structure interaction simulation of the aortic and mitral valves in a realistic 3D left ventricle model.

    PubMed

    Mao, Wenbin; Caballero, Andrés; McKay, Raymond; Primiano, Charles; Sun, Wei

    2017-01-01

    In this study, we present a fully-coupled fluid-structure interaction (FSI) framework that combines smoothed particle hydrodynamics (SPH) and nonlinear finite element (FE) method to investigate the coupled aortic and mitral valves structural response and the bulk intraventricular hemodynamics in a realistic left ventricle (LV) model during the entire cardiac cycle. The FSI model incorporates valve structures that consider native asymmetric leaflet geometries, anisotropic hyperelastic material models and human material properties. Comparison of FSI results with subject-specific echocardiography data demonstrates that the SPH-FE approach is able to quantitatively predict the opening and closing times of the valves, the mitral leaflet opening and closing angles, and the large-scale intraventricular flow phenomena with a reasonable agreement. Moreover, comparison of FSI results with a LV model without valves reveals substantial differences in the flow field. Peak systolic velocities obtained from the FSI model and the LV model without valves are 2.56 m/s and 1.16 m/s, respectively, compared to the Doppler echo data of 2.17 m/s. The proposed SPH-FE FSI framework represents a further step towards modeling patient-specific coupled LV-valve dynamics, and has the potential to improve our understanding of cardiovascular physiology and to support professionals in clinical decision-making.

  11. Measuring Regional Changes in the Diastolic Deformation of the Left Ventricle of SHR Rats Using microPET Technology and Hyperelastic Warping

    SciTech Connect

    Gullberg, Grant T; VERESS , ALEXANDER I.; WEISS, JEFFREY A.; HUESMAN, RONALD H.; REUTTER, BRYAN W.; TAYLOR , SCOTT E.; SITEK , AREK; FENG, BING; YANG , YONGFENG; GULLBERG, GRANT T.

    2008-04-04

    The objective of this research was to assess applicability of a technique known as hyperelastic warping for the measurement of local strains in the left ventricle (LV) directly from microPET image data sets. The technique uses differences in image intensities between template (reference) and target (loaded) image data sets to generate a body force that deforms a finite element (FE) representation of the template so that it registers with the target images. For validation, the template image was defined as the end-systolic microPET image data set from a Wistar Kyoto (WKY) rat. The target image was created by mapping the template image using the deformation results obtained from a FE model of diastolic filling. Regression analysis revealed highly significant correlations between the simulated forward FE solution and image derived warping predictions for fiber stretch (R2 = 0.96), circumferential strain (R2 = 0.96), radial strain (R2 = 0.93), and longitudinal strain (R2 = 0.76) (p<0.001for all cases). The technology was applied to microPET image data of two spontaneously hypertensive rats (SHR) and a WKY control. Regional analysis revealed that, the lateral freewall in the SHR subjects showed the greatest deformation compared with the other wall segments. This work indicates that warping can accurately predict the strain distributions during diastole from the analysis of microPET data sets.

  12. Three-dimensional structure of the flow inside the left ventricle of the human heart

    NASA Astrophysics Data System (ADS)

    Fortini, S.; Querzoli, G.; Espa, S.; Cenedese, A.

    2013-11-01

    The laboratory models of the human heart left ventricle developed in the last decades gave a valuable contribution to the comprehension of the role of the fluid dynamics in the cardiac function and to support the interpretation of the data obtained in vivo. Nevertheless, some questions are still opened and new ones stem from the continuous improvements in the diagnostic imaging techniques. Many of these unresolved issues are related to the three-dimensional structure of the left ventricular flow during the cardiac cycle. In this paper, we investigated in detail this aspect using a laboratory model. The ventricle was simulated by a flexible sack varying its volume in time according to a physiologically shaped law. Velocities measured during several cycles on series of parallel planes, taken from two orthogonal points of view, were combined together in order to reconstruct the phase-averaged, three-dimensional velocity field. During the diastole, three main steps are recognized in the evolution of the vortical structures: (1) straight propagation in the direction of the long axis of a vortex ring originated from the mitral orifice; (2) asymmetric development of the vortex ring on an inclined plane; and (3) single vortex formation. The analysis of three-dimensional data gives the experimental evidence of the reorganization of the flow in a single vortex persisting until the end of the diastole. This flow pattern seems to optimize the cardiac function since it directs velocity towards the aortic valve just before the systole and minimizes the fraction of blood residing within the ventricle for more cycles.

  13. Differential Regulation of PDE5 Expression in Left and Right Ventricles of Feline Hypertrophy Models

    PubMed Central

    Shan, Xiaoyin; Margulies, Kenneth B.

    2011-01-01

    Background Though long known to affect smooth muscle biology, recent studies indicate that phosphodiesterase 5 (PDE5) is also expressed in myocardium. Recognizing that the regulation of PDE5 in hypertrophy is not well understood, we assessed the response of PDE5 expression and the level of cGMP-dependent kinase I (cGKI) in the left and right ventricles of feline hypertrophy models. Methodology/Principal Findings Using a cDNA library of feline aortic smooth muscle cells, we identified and cloned PDE5 cDNA for the first time in this species. The sequence shares 98% identity with its human orthologue at the amino acid level. E. coli expression of the cloned allele allowed selection of antibodies with appropriate specificity, facilitating the analysis of PDE5 expression in feline models created by selective proximal aortic (Ao) or pulmonary artery (PA) banding that resulted in hypertrophy of the left ventricle (LV) and right ventricle (RV), respectively. We demonstrated that PDE5 expression responded differentially with a decreased expression in the LV and an increased expression in the RV in the Ao-banded model. Similarly, in the PA-banded model, LV showed reduced expression while the RV expression was unaltered. In addition, the expression of cGKI was significantly decreased in the RV of Ao-banded group, correlating inversely with the increase in PDE5 expression. Conclusions/Significance The differential regulation of PDE5 and cGKI expression suggests that the mechanisms involved in hypertrophy could be different in RV vs. LV. Reciprocal PDE5 and cGKI expression in the RV of Ao-banded model suggests functional significance for PDE5 up-regulation. PMID:21625548

  14. Epicardial catheter ablation of ventricular tachycardia in no entry left ventricle: mechanical aortic and mitral valves.

    PubMed

    Soejima, Kyoko; Nogami, Akihiko; Sekiguchi, Yukio; Harada, Tomoo; Satomi, Kazuhiro; Hirose, Takeshi; Ueda, Akiko; Miwa, Yousuke; Sato, Toshiaki; Nishio, Satoru; Shirai, Yasuhiro; Kowase, Shinya; Murakoshi, Nobuyuki; Kunugi, Shinobu; Murata, Hiroshige; Nitta, Takashi; Aonuma, Kazutaka; Yoshino, Hideaki

    2015-04-01

    In patients with mechanical aortic and mitral valves and left ventricular tachycardia, catheter ablation may be prevented by limited access to the left ventricle. In our series of 6 patients, 2 patients underwent direct surgical ablation and 4 underwent epicardial catheter ablation via a pericardial window. All patients had abnormal low voltage areas with fractionated or delayed isolated potentials on the apical epicardium. Most of the ventricular tachycardias were targeted by pace mapping. Sites with a good pace match or abnormal electrograms were ablated using an irrigated radiofrequency ablation catheter. A microscopic pathological evaluation of the resected tissue from 2 of the open-heart ablation patients revealed dense fibrosis on the epicardium compared with the endocardium, supporting the feasibility of an epicardial ablation for the ventricular tachycardia. Epicardial catheter ablation of ventricular tachycardia is a potentially useful therapy in patients who have mechanical aortic and mitral valves. © 2015 American Heart Association, Inc.

  15. Left ventricle pseudoaneurysm in a transplanted heart from a car crash victim donor.

    PubMed

    Urbanowicz, Tomasz; Katarzyński, Sławomir; Puślecki, Mateusz; Budniak, Wiktor; Araszkiewicz, Aleksander; Łanocha, Magdalena; Pyda, Małgorzata; Straburzyńska-Migaj, Ewa; Jemielity, Marek

    2014-06-26

    Pseudoaneurysm is a very rare and unusual form of myocardial rupture, with complications such as chest trauma, inflammation, acute myocardial infarction, and infection. Although this rare complication has already been reported, it has never been found in a transplanted patient. We present the case of a 54-year-old women waiting on the urgent list who underwent heart transplantation. The donor of the organ died in a car accident. Although preoperative echocardiography had not revealed any signs of heart injury, a superficial small (3 × 3 mm hematoma) was detected on harvesting. After implantation, intraoperative echocardiography was satisfactory, with no signs of wall motion disturbances, and left ventricle ejection fraction was estimated at 50%. The postoperative period was uneventful. Three weeks after surgery, a left ventricle pseudoaneurysm was found on routine MRI. The aneurysm wall consisted of only an epicardial layer. There was an 8-mm-wide gap in the myocardial wall next to the endocardium and with the width of 4 mm beneath the epicardium. On repeated MRI performed 3 months thereafter, the pseudoaneurysm was filled by thrombus. The presented case illustrates the necessity of careful inspection of the organ reported for transplantation from a donor who died from high-speed motor vehicle crash injuries. Additional diagnostic steps like MRI imaging are obligatory after transplantation, especially when the organ was harvested from a motor vehicle crash victim.

  16. Prenatal Diagnosis and Outcome of Fetuses with Double-Inlet Left Ventricle

    PubMed Central

    Gidvani, Monisha; Ramin, Kirk; Gessford, Ellen; Aguilera, Marijo; Giacobbe, Lauren; Sivanandam, Shanthi

    2011-01-01

    The aim of this study is to characterize the in utero presentation of the subtype of double-inlet left ventricle (DILV), a rare congenital heart disease, and assess the postnatal outcome. We retrospectively studied fetuses diagnosed prenatally with DILV between 2007 and 2011. We reviewed the prenatal and postnatal echocardiograms, clinical presentations, karyotypes, and the postnatal outcomes. There were eight fetuses diagnosed with DILV with L-transposition of the great vessels (S, L, L). Mean gestational age at diagnosis was 24.7 weeks. Of these, four fetuses (50%) had pulmonary atresia. One fetus (12.5%) also had tricuspid atresia and coarctation of the aorta and died at 17 months of age. Complete heart block and long QT syndrome was present in one fetus (12.5%), who died shortly after birth. There were no extracardiac or karyotypic abnormalities. Six (75%) infants are alive and doing well. Double-inlet left ventricle with varied presentation can be accurately diagnosed prenatally. The outcome of fetuses is good in the absence of associated rhythm abnormalities with surgically staged procedures leading to a Fontan circulation. PMID:23705101

  17. MRI-based strain and strain rate analysis of left ventricle: a modified hierarchical transformation model

    PubMed Central

    2015-01-01

    Background Different from other indicators of cardiac function, such as ejection fraction and transmitral early diastolic velocity, myocardial strain is promising to capture subtle alterations that result from early diseases of the myocardium. In order to extract the left ventricle (LV) myocardial strain and strain rate from cardiac cine-MRI, a modified hierarchical transformation model was proposed. Methods A hierarchical transformation model including the global and local LV deformations was employed to analyze the strain and strain rate of the left ventricle by cine-MRI image registration. The endocardial and epicardial contour information was introduced to enhance the registration accuracy by combining the original hierarchical algorithm with an Iterative Closest Points using Invariant Features algorithm. The hierarchical model was validated by a normal volunteer first and then applied to two clinical cases (i.e., the normal volunteer and a diabetic patient) to evaluate their respective function. Results Based on the two clinical cases, by comparing the displacement fields of two selected landmarks in the normal volunteer, the proposed method showed a better performance than the original or unmodified model. Meanwhile, the comparison of the radial strain between the volunteer and patient demonstrated their apparent functional difference. Conclusions The present method could be used to estimate the LV myocardial strain and strain rate during a cardiac cycle and thus to quantify the analysis of the LV motion function. PMID:25602778

  18. Characterization of human left ventricle flow patterns using ultrasound and Lagrangian coherent structures

    NASA Astrophysics Data System (ADS)

    Hendabadi, Sahar; Del Alamo, Juan Carlos; Benito, Yolanda; Yotti, Raquel; Bermejo, Javier; Shadden, Shawn

    2012-11-01

    We discuss work towards understanding human left ventricle (LV) transport and mixing characteristics in normal subjects and patients with dilated cardiomyopathy. Prior studies have shown that the fluid dynamics in the left ventricle (LV) play a major role in dictating overall cardiac health. This study utilizes a noninvasive method to obtain planar velocity data over the apical long-axis view of the LV from color Doppler and B-mode ultrasound measurements. We use a Lagrangian measure to study unsteady behavior of blood transport inside the LV. We compute finite-time Lyapunov exponent (FTLE) fields to extract Lagrangian coherent structures (LCS) from the empirical data. This application presents a particular challenge to Lagrangian computations due to the presence of moving flux, and no-flux, boundaries. We describe a method for unstructured grid generation from the LV motion, and LCS computation on the deforming unstructured grid. Results demonstrate that LCS reveal the moving boundaries confining the blood volume injected to the LV in diastole and ejected into the aorta in systole. We discuss findings related to the quantification of the LV vortex, whose geometry and motion is thought to be an important indicator of cardiac health.

  19. Computational analysis of blood flow in an integrated model of the left ventricle and the aorta.

    PubMed

    Nakamura, Masanori; Wada, Shigeo; Yamaguchi, Takami

    2006-12-01

    To study the effects of intraventricular flow dynamics on the aortic flow, we created an integrated model of the left ventricle and aorta and conducted a computer simulation of diastolic and systolic blood flow within this model. The results demonstrated that the velocity profile at the aortic annulus changed dynamically, and was influenced by the intraventricular flow dynamics. The profile was almost flat in early systole but became nonuniform as systole progressed, and was skewed toward the posterior side in midsystole and toward the anterior side in later systole. At a distance from the aortic annulus, a different velocity profile was induced by the twisting and torsion of the aorta. In the ascending aorta, the fastest flow was initially located in the posteromedial sector, and it moved to the posterior section along the circumference as systole progressed. The nonuniformity of the aortic inflow gave rise to a complex wall shear stress (WSS) distribution in the aorta. A comparison of the WSS distribution obtained in this integrated analysis with that obtained in flow calculations using an isolated aorta model with Poiseuille and flat inlet conditions showed that intraventricular flow affected the WSS distribution in the ascending aorta. These results address the importance of an integrated analysis of flow in the left ventricle and aorta.

  20. Transition from compensatory hypertrophy to dilated, failing left ventricles in Dahl salt-sensitive rats.

    PubMed

    Inoko, M; Kihara, Y; Morii, I; Fujiwara, H; Sasayama, S

    1994-12-01

    To establish an experimental model for studying a specific transitional stage for compensatory hypertrophy to heart failure, we studied the pathophysiology of the left ventricle (LV) in Dahl salt-sensitive (DS) rats fed a high-salt diet. DS rats fed an 8% NaCl diet after the age of 6 wk developed concentric LV hypertrophy at 11 wk, followed by marked LV dilatation at 15-20 wk. During the latter stage, the DS rats showed labored respiration with LV global hypokinesis. All the DS rats died within 1 wk by massive pulmonary congestion. The dissected left ventricles revealed chamber dilatation and a marked increase in mass without myocardial necrosis. In contrast, corresponding Dahl salt-resistant (DR) rats fed the same diet showed neither mortality nor any of these pathological changes. The in vivo LV end-systolic pressure-volume relationship shifted to the right with a less steep slope in the failing DS rats compared with that in age-matched DR rats. Isometric contractions of LV papillary muscles isolated from these DS rats showed reduced tension development in the failing stage, but normal tension development in the hypertrophied stage. In conclusion, the DS rat fed a high-salt diet is a useful model showing rapidly developing congestive heart failure, in which the transition from compensatory hypertrophy to decompensatory dilatation of LV is easily and consistently manifested.

  1. Left ventricular wall stress compendium.

    PubMed

    Zhong, L; Ghista, D N; Tan, R S

    2012-01-01

    Left ventricular (LV) wall stress has intrigued scientists and cardiologists since the time of Lame and Laplace in 1800s. The left ventricle is an intriguing organ structure, whose intrinsic design enables it to fill and contract. The development of wall stress is intriguing to cardiologists and biomedical engineers. The role of left ventricle wall stress in cardiac perfusion and pumping as well as in cardiac pathophysiology is a relatively unexplored phenomenon. But even for us to assess this role, we first need accurate determination of in vivo wall stress. However, at this point, 150 years after Lame estimated left ventricle wall stress using the elasticity theory, we are still in the exploratory stage of (i) developing left ventricle models that properly represent left ventricle anatomy and physiology and (ii) obtaining data on left ventricle dynamics. In this paper, we are responding to the need for a comprehensive survey of left ventricle wall stress models, their mechanics, stress computation and results. We have provided herein a compendium of major type of wall stress models: thin-wall models based on the Laplace law, thick-wall shell models, elasticity theory model, thick-wall large deformation models and finite element models. We have compared the mean stress values of these models as well as the variation of stress across the wall. All of the thin-wall and thick-wall shell models are based on idealised ellipsoidal and spherical geometries. However, the elasticity model's shape can vary through the cycle, to simulate the more ellipsoidal shape of the left ventricle in the systolic phase. The finite element models have more representative geometries, but are generally based on animal data, which limits their medical relevance. This paper can enable readers to obtain a comprehensive perspective of left ventricle wall stress models, of how to employ them to determine wall stresses, and be cognizant of the assumptions involved in the use of specific models.

  2. Incidental Finding of Malpositioned Pacing Lead in the Left Ventricle in a Patient With Subacute Subdural Hematoma

    PubMed Central

    Syed, Asma; Salim, Sohail; Castillo, Ricardo

    2012-01-01

    Malposition of the right ventricular lead into the left ventricle is an unusual complication of challenging management. We report a case of an elderly woman with a dual chamber permanent pacemaker implanted 2 months before admission because of high grade AV block, who presented to our institution with sub acute subdural hematoma along the left fronto-parietal area. Incidental ventricular pacemaker lead in the left ventricle was found on chest CT scan. The patient was not candidate for anticoagulation due to her recent subdural hematoma, hence a discussion about the risks of explantation of the pacemaker lead led to patient’s lead extraction without any complication.

  3. Diastolic heart failure--abnormalities in active relaxation and passive stiffness of the left ventricle.

    PubMed

    Zile, Michael R; Baicu, Catalin F; Gaasch, William H

    2004-05-06

    Patients with signs and symptoms of heart failure and a normal left ventricular ejection fraction are said to have diastolic heart failure. It has traditionally been thought that the pathophysiological cause of heart failure in these patients is an abnormality in the diastolic properties of the left ventricle; however, this hypothesis remains largely unproven. We prospectively identified 47 patients who met the diagnostic criteria for definite diastolic heart failure; all the patients had signs and symptoms of heart failure, a normal ejection fraction, and an increased left ventricular end-diastolic pressure. Ten patients who had no evidence of cardiovascular disease served as controls. Left ventricular diastolic function was assessed by means of cardiac catheterization and echocardiography. The patients with diastolic heart failure had abnormal left ventricular relaxation and increased left ventricular chamber stiffness. The mean (+/-SD) time constant for the isovolumic-pressure decline (tau) was longer in the group with diastolic heart failure than in the control group (59+/-14 msec vs. 35+/-10 msec, P=0.01). The diastolic pressure-volume relation was shifted up and to the left in the patients with diastolic heart failure as compared with the controls. The corrected left ventricular passive-stiffness constant was significantly higher in the group with diastolic heart failure than in the control group (0.03+/-0.01 vs. 0.01+/-0.01, P<0.001). Patients with heart failure and a normal ejection fraction have significant abnormalities in active relaxation and passive stiffness. In these patients, the pathophysiological cause of elevated diastolic pressures and heart failure is abnormal diastolic function. Copyright 2004 Massachusetts Medical Society

  4. Traumatic false aneurysms of the left ventricle after an attempt at video-thoracoscopic surgery.

    PubMed

    Guihaire, Julien; Flecher, Erwan; de Latour, Bertrand; Verhoye, Jean-Philippe

    2012-07-01

    OBJECTIVES Video-thoracoscopic surgery (VTS) has been accepted as a safe and credible technique since 1990. Lung injury is one of the main perioperative complications. Few data are available about cardiac trauma and VTS-related false aneurysm of the left ventricular (LV) wall has not yet been reported. METHODS A 62-year old woman presented with a left thoracic empyema. Video-thoracoscopy was attempted for bacterial sampling and surgical drain of the pleura. A rapid conversion to open thoracotomy was necessary to control massive bleeding after the first thoracic port intrusion. An apical systolic murmur was found 2 weeks later during a systematic clinical examination. The patient was asymptomatic and had no personal history of cardiac disease. RESULTS Colour Doppler imaging showed two spurious aneurysms on the LV wall without any haemopericardium. Pericardial enhancement around the left ventricle was observed on the chest computerized tomography scan with the injection of contrast. After the careful excision of the two false aneurysms, a surgical repair was strengthened with a suture under a cardiopulmonary bypass. The postoperative course was uneventful and the patient was safe at 3 years. CONCLUSIONS This is the first report of LV traumatic false aneurysms secondary to an attempt of a video-thoracoscopic procedure. This is a rare but life-threatening complication because of the risk of spontaneous rupture. Left persistent thoracic empyemas associated with the ipsilateral mediastinum deviation carry a high risk of myocardial damage related to the trocar port intrusion.

  5. On numerically accurate finite element

    NASA Technical Reports Server (NTRS)

    Nagtegaal, J. C.; Parks, D. M.; Rice, J. R.

    1974-01-01

    A general criterion for testing a mesh with topologically similar repeat units is given, and the analysis shows that only a few conventional element types and arrangements are, or can be made suitable for computations in the fully plastic range. Further, a new variational principle, which can easily and simply be incorporated into an existing finite element program, is presented. This allows accurate computations to be made even for element designs that would not normally be suitable. Numerical results are given for three plane strain problems, namely pure bending of a beam, a thick-walled tube under pressure, and a deep double edge cracked tensile specimen. The effects of various element designs and of the new variational procedure are illustrated. Elastic-plastic computation at finite strain are discussed.

  6. Automatic segmentation of left ventricle in cardiac cine MRI images based on deep learning

    NASA Astrophysics Data System (ADS)

    Zhou, Tian; Icke, Ilknur; Dogdas, Belma; Parimal, Sarayu; Sampath, Smita; Forbes, Joseph; Bagchi, Ansuman; Chin, Chih-Liang; Chen, Antong

    2017-02-01

    In developing treatment of cardiovascular diseases, short axis cine MRI has been used as a standard technique for understanding the global structural and functional characteristics of the heart, e.g. ventricle dimensions, stroke volume and ejection fraction. To conduct an accurate assessment, heart structures need to be segmented from the cine MRI images with high precision, which could be a laborious task when performed manually. Herein a fully automatic framework is proposed for the segmentation of the left ventricle from the slices of short axis cine MRI scans of porcine subjects using a deep learning approach. For training the deep learning models, which generally requires a large set of data, a public database of human cine MRI scans is used. Experiments on the 3150 cine slices of 7 porcine subjects have shown that when comparing the automatic and manual segmentations the mean slice-wise Dice coefficient is about 0.930, the point-to-curve error is 1.07 mm, and the mean slice-wise Hausdorff distance is around 3.70 mm, which demonstrates the accuracy and robustness of the proposed inter-species translational approach.

  7. A coupled chemo-fluidic computational model for thrombogenesis in infarcted left ventricles.

    PubMed

    Seo, Jung Hee; Abd, Thura; George, Richard T; Mittal, Rajat

    2016-06-01

    A coupled chemo-fluidic computational model for investigating flow-mediated thrombogenesis in infarcted left ventricles (LVs) is proposed. LV thrombus (LVT) formation after the acute myocardial infarction (AMI) may lead to thromboembolic events that are associated with high mortality and morbidity, and reliable stratification of LVT risk is the key to managing the treatment of AMI patients. There have been several studies emphasizing the importance of LV blood flow patterns on thrombus formation; however, given the complex interplay between ventricular flow dynamics and biochemistry of thrombogenesis, current understanding is mostly empirical. In the present model, blood flow in the LV is obtained by solving the incompressible Navier-Stokes equations, and this is coupled to the biochemical modeling of the coagulation cascade, platelet activation, and fibrinogen polymerization. The coupled model is used to examine the effect of ventricular flow patterns on thrombogenesis in modeled ventricles. It is expected that the method developed here will enable in-depth studies of thrombogenesis in patient-derived infarcted LV models. Copyright © 2016 the American Physiological Society.

  8. Expression of Bax Protein and Morphological Changes in the Myocardium in Experimental Acute Pressure Overload of the Left Ventricle.

    PubMed

    Blagonravov, M L; Korshunova, A Yu; Azova, M M; Bryk, A A; Frolov, V A

    2016-06-01

    The expression of Bax protein, marker of intracellular pathway of apoptosis initiation, in viable left ventricular cardiomyocytes and morphological changes in the myocardium in acute pressure overload of the left ventricle were studied in experiment on male rabbits. The content of Bax protein in the cardiomyocyte cytoplasm decreased, this indicating that the mitochondrial pathway was not involved in the realization of the apoptotic program. This decrease was associated with manifest destructive changes in the left ventricular myocardium.

  9. Strain measurement in the left ventricle during systole with deformable image registration ✩

    PubMed Central

    Phatak, Nikhil S.; Maas, Steve A.; Veress, Alexander I.; Pack, Nathan A.; Di Bella, Edward V.R.; Weiss, Jeffrey A.

    2009-01-01

    The objective of this study was to validate a deformable image registration technique, termed Hyperelastic Warping, for left ventricular strain measurement during systole using cine-gated, nontagged MR images with strains measured from tagged MRI. The technique combines deformation from high resolution, non-tagged MR image data with a detailed computational model, including estimated myocardial material properties, fiber direction, and active fiber contraction, to provide a comprehensive description of myocardial contractile function. A normal volunteer (male, age 30) with no history of cardiac pathology was imaged with a 1.5 T Siemens Avanto clinical scanner using a TrueFISP imaging sequence and a 32-channel cardiac coil. Both tagged and non-tagged cine MR images were obtained. The Hyperelastic Warping solution was evolved using a series of non-tagged images in ten intermediate phases from end-diastole to end-systole. The solution may be considered as ten separate warping problems with multiple templates and targets. At each stage, an active contraction was initially applied to a finite element model, and then image-based warping penalty forces were utilized to generate the final registration. Warping results for circumferential strain (R2 = 0.75) and radial strain (R2 = 0.78) were strongly correlated with results obtained from tagged MR images analyzed with a Harmonic Phase (HARP) algorithm. Results for fiber stretch, LV twist, and transmural strain distributions were in good agreement with experimental values in the literature. In conclusion, Hyperelastic Warping provides a unique alternative for quantifying regional LV deformation during systole without the need for tags. PMID:18948056

  10. Reduced levels of globular and asymmetric forms of acetylcholinesterase in rat left ventricle with pressure overload hypertrophy.

    PubMed

    Nyquist-Battie, C; Hagler, K E; Love, S

    1994-01-01

    The aim of the present work was to determine the effect of abdominal aortic stenosis on molecular forms of acetylcholinesterase (AChE) in rat heart. Pressure-overload, left ventricular hypertrophy was produced in male Sprague-Dawley rats by suprarenal abdominal aortic constriction. After two weeks the relative heart weight was increased over 20% compared to sham-surgical controls, mostly due to left ventricular enlargement. Aortic constriction reduced AChE activity per wet weight and per unit protein by 25-30% in the left ventricle and interventricular septum, but not in the other chambers. However, total AChE activity per chamber was normal in the left ventricle and interventricular septum, but was elevated in the atria. The molecular forms of AChE were separated in linear sucrose gradients and their specific activities were calculated from the resulting percent activities and total AChE activities. This data showed that although aortic constriction had no effect on ratios of the various forms, it did reduce the specific activities of globular and asymmetric forms in the left ventricle and interventricular septum. The reduced AChE activity suggests that slower rates of ACh hydrolysis occur in the left ventricle in pressure-overload hypertrophy.

  11. 3D Motion Modeling and Reconstruction of Left Ventricle Wall in Cardiac MRI.

    PubMed

    Yang, Dong; Wu, Pengxiang; Tan, Chaowei; Pohl, Kilian M; Axel, Leon; Metaxas, Dimitris

    2017-06-01

    The analysis of left ventricle (LV) wall motion is a critical step for understanding cardiac functioning mechanisms and clinical diagnosis of ventricular diseases. We present a novel approach for 3D motion modeling and analysis of LV wall in cardiac magnetic resonance imaging (MRI). First, a fully convolutional network (FCN) is deployed to initialize myocardium contours in 2D MR slices. Then, we propose an image registration algorithm to align MR slices in space and minimize the undesirable motion artifacts from inconsistent respiration. Finally, a 3D deformable model is applied to recover the shape and motion of myocardium wall. Utilizing the proposed approach, we can visually analyze 3D LV wall motion, evaluate cardiac global function, and diagnose ventricular diseases.

  12. Rattus norvegicus BN/SHR liver and heart left ventricle ribosomal RNA depleted directional RNA sequencing.

    PubMed

    Wyler, Emanuel; van Heesch, Sebastiaan; Adami, Eleonora; Hubner, Norbert; Landthaler, Markus

    2017-08-11

    The spontaneously hypertensive rat strain is a frequently used disease model. In a previous study, we measured translational efficiency from this strain and BN-Lx animals. Here, we describe long RNA sequencing reads from ribosomal RNA depleted samples from the same animals. This data can be used to investigate splicing-related events. RNA was extracted from rat liver and heart left ventricle from BN-Lx and SHR/Ola rats in biological replicates. Ribosomal RNA was removed and the samples subjected to directional high-throughput RNA-sequencing. Read and alignment statistics indicate high quality of the data. The raw sequencing reads are freely available on the NCBI short read archive and can be used for further research on tissue and strain differences, or analysed together with other published high-throughput data from the same animals.

  13. 3D Finite Time Lyapunov Exponents in a left ventricle laboratory model

    NASA Astrophysics Data System (ADS)

    Grazia Badas, Maria; Espa, Stefania; Fortini, Stefania; Querzoli, Giorgio

    2015-05-01

    Finite Time Lyapunov Exponents (FTLEs) are a powerful means to infer characteristic features of the flow that cannot be revealed by other Eulerian criteria. Recently FTLEs are becoming popular also in the medical context, for instance in the analysis of vascular flow measured by means of Magnetic Resonance Imaging. However, many of the FTLE experimental works are based only on two-dimensional velocity fields, moreover those computed on in-vivo data cannot be obtained under controlled and repeatable conditions. Here we present the 3D FTLE evolution inside a Left Ventricle (LV) laboratory model mimicking physiological human conditions. The investigation of FTLE fields highlights distinctive features of the cardiac flow and gives an insight on the physiological development of the Lagrangian Coherent Structures (LCS) that optimize the LV refill.

  14. Automatic localization of the left ventricle in cardiac MRI images using deep learning.

    PubMed

    Emad, Omar; Yassine, Inas A; Fahmy, Ahmed S

    2015-08-01

    Automatic localization of the left ventricle (LV) in cardiac MRI images is an essential step for automatic segmentation, functional analysis, and content based retrieval of cardiac images. In this paper, we introduce a new approach based on deep Convolutional Neural Network (CNN) to localize the LV in cardiac MRI in short axis views. A six-layer CNN with different kernel sizes was employed for feature extraction, followed by Softmax fully connected layer for classification. The pyramids of scales analysis was introduced in order to take account of the different sizes of the heart. A publically-available database of 33 patients was used for learning and testing. The proposed method was able it localize the LV with 98.66%, 83.91% and 99.07% for accuracy, sensitivity and specificity respectively.

  15. Pattern recognition of abnormal left ventricle wall motion in cardiac MR.

    PubMed

    Lu, Yingli; Radau, Perry; Connelly, Kim; Dick, Alexander; Wright, Graham

    2009-01-01

    There are four main problems that limit application of pattern recognition techniques for recognition of abnormal cardiac left ventricle (LV) wall motion: (1) Normalization of the LV's size, shape, intensity level and position; (2) defining a spatial correspondence between phases and subjects; (3) extracting features; (4) and discriminating abnormal from normal wall motion. Solving these four problems is required for application of pattern recognition techniques to classify the normal and abnormal LV wall motion. In this work, we introduce a normalization scheme to solve the first and second problems. With this scheme, LVs are normalized to the same position, size, and intensity level. Using the normalized images, we proposed an intra-segment classification criterion based on a correlation measure to solve the third and fourth problems. Application of the method to recognition of abnormal cardiac MR LV wall motion showed promising results.

  16. Combining existing numerical models with data assimilation using weighted least-squares finite element methods.

    PubMed

    Rajaraman, Prathish K; Manteuffel, T A; Belohlavek, M; Heys, Jeffrey J

    2017-01-01

    A new approach has been developed for combining and enhancing the results from an existing computational fluid dynamics model with experimental data using the weighted least-squares finite element method (WLSFEM). Development of the approach was motivated by the existence of both limited experimental blood velocity in the left ventricle and inexact numerical models of the same flow. Limitations of the experimental data include measurement noise and having data only along a two-dimensional plane. Most numerical modeling approaches do not provide the flexibility to assimilate noisy experimental data. We previously developed an approach that could assimilate experimental data into the process of numerically solving the Navier-Stokes equations, but the approach was limited because it required the use of specific finite element methods for solving all model equations and did not support alternative numerical approximation methods. The new approach presented here allows virtually any numerical method to be used for approximately solving the Navier-Stokes equations, and then the WLSFEM is used to combine the experimental data with the numerical solution of the model equations in a final step. The approach dynamically adjusts the influence of the experimental data on the numerical solution so that more accurate data are more closely matched by the final solution and less accurate data are not closely matched. The new approach is demonstrated on different test problems and provides significantly reduced computational costs compared with many previous methods for data assimilation. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  17. Echocardiographic assessment of feline false tendons and their relationship with focal thickening of the left ventricle.

    PubMed

    Wolf, O A; Imgrund, M; Wess, G

    2017-02-01

    False tendons (FTs) are string-like structures in the left ventricle. A FT might produce focal thickening at its insertion region of the left ventricle, which could be mistaken for focal hypertrophic cardiomyopathy. To perform a prospective, echocardiographic follow-up examination of feline FTs and compare the wall thickness at the FT insertion region and a normal region without FTs at both examinations. One hundred twenty-eight cats with one or multiple FTs without other cardiac abnormalities or systemic disease. Measurements of the interventricular septum at end-diastole at a region with and without FT insertion were performed using two-dimensional echocardiography at both examinations and compared statistically using a Student's t-test. The follow-up interval ranged from 5 to 110 months (mean, 33 months). Myocardial wall segments with FT insertions were significantly thicker compared with neighboring wall regions in the long axis, but not in the short-axis views obtained. Comparing the wall thickness of follow-up examinations with the initial examination, revealed a significant growth of both FT and non-FT segments. However, differences in growth between the FT region and region without FTs were not statistically different. Many normal cats have FTs, associated with focal thickening compared with neighboring regions. This thickening can increase over time, proportionate to growth in other (non-FT) segments. The association of such thickening with an FT and the absence of disproportionate growth in this segment over time suggests that these segments are simply thicker related to FT insertion. Copyright © 2016. Published by Elsevier B.V.

  18. The video technique developed for measuring epicardial strains on guinea pig's left ventricle.

    PubMed

    Kirn, Borut; Starc, Vito

    2005-01-01

    Single-plain video used for measurements of epicardial strains is a technique that yields minor interference with the studied mechanical properties of the ventricle. Due to its low temporal resolution, the existing technique is, however, not appropriate for small animals. We questioned whether the technique could be improved enough to cope with higher heart rates and miniaturization necessary for experiments on rats, mice and guinea pigs. Therefore, we developed a high-speed video system and used it for measuring epicardial strains in guinea pig hearts in situ with the open chest. The improvement was achieved in video hardware (camera: Dalsa D6-0256; framegraber: EPIX PIXCI D32) and software, the markers (glowing acrylate crystals; diameter approximately 0.15 mm) and illumination (UVA light, OSRAM L). Three markers were attached onto the epicardium in the equatorial region of the left ventricular free wall, 1.5 mm apart, with fibrin glue. From their coordinates, we calculated two-dimensional finite strains with end diastole as the reference point. The accuracy of the displacement measurement of the technique and the error introduced by approximate-visual estimation of the left ventricle coordinate system were evaluated. The accuracy of the displacement measurement was +/-1.6 microm and the temporal resolution was 2 ms. Error due to approximate coordinate system orientation was +/-3% of the strain amplitude. The typical amplitude of strains was -0.06, -0.11 and 0.04 in circumferential, axial direction and in-plane shear, respectively. The improvements enable us to perform physiologically relevant measurements of epicardial deformations on guinea pig heart.

  19. Domain decomposition methods for mortar finite elements

    SciTech Connect

    Widlund, O.

    1996-12-31

    In the last few years, domain decomposition methods, previously developed and tested for standard finite element methods and elliptic problems, have been extended and modified to work for mortar and other nonconforming finite element methods. A survey will be given of work carried out jointly with Yves Achdou, Mario Casarin, Maksymilian Dryja and Yvon Maday. Results on the p- and h-p-version finite elements will also be discussed.

  20. Coupled Hemodynamic-Biochemical Modeling of Thrombus Formation in Infarcted Left Ventricles

    NASA Astrophysics Data System (ADS)

    Seo, Jung Hee; Vedula, Vijay; George, Richard; Mittal, Rajat

    2013-11-01

    Patients with heart failure (HF) and left ventricular (LV) systolic dysfunction have higher rates of thromboembolic events including embolic stroke and peripheral arterial thrombi. A common cause of arterial emboli in HF patients is myocardial infarction (MI) and subsequent left ventricular thrombus (LVT) formation. Stagnation of blood and endocardial injury are hypothesized to promote the development of LVT. The identification of high risk patients and the pharmacologic prevention of LVT formation are the keys to preventing embolic events. Stratification of patients at risk for LVT formation is currently limited, and primarily based on global assessment of ventricular function and image based assessment of ventricular wall motion. In this study, we explore a method to predict LVT risk using a multi-physics computational model. The blood flow in the left ventricle is simulated by solving the incompressible Navier-Stokes equation using an immersed boundary method and this is coupled to a convection-diffusion-reaction equation based model of platelet activation and coagulation. The results are then correlated with the other hemodynamic metrics such as wall shear stress and residence time to develop quantitative metrics for the LVT risk prediction. Supported by NSF CDI-Type II grant IOS-1124804, Computational resource by XSEDE NSF grant TG-CTS100002.

  1. Coronary-Cameral Fistula Connecting the Left Anterior Descending Artery and the First Obtuse Marginal Artery to the Left Ventricle: A Rare Finding

    PubMed Central

    Khan, Arshad Ameer; Qureshi, Ghazanfar; Balakrishna, Pragathi

    2017-01-01

    Coronary-cameral fistulas are rare congenital malformations, often incidentally found during cardiac catheterizations. The majority of these fistulas are congenital in nature but can be acquired secondary to trauma or invasive cardiac procedures. These fistulas most commonly originate in the right coronary artery and terminate into the right ventricle and least frequently drain into the left ventricle. Depending upon their size and location, coronary-cameral fistulas can lead to congestive heart failure, myocardial infarction, and bacterial endocarditis. We describe a case of 49-year-old woman who presented with worsening exertional dyspnea and leg swelling. Transthoracic echocardiogram revealed an ejection fraction of 35%. Cardiac catheterization demonstrated a fistula connecting the left anterior descending artery and the first obtuse marginal artery to the left ventricle. In this report, the authors provide a concise review on coronary fistulas, complications, and management options. PMID:28194284

  2. ANSYS duplicate finite-element checker routine

    NASA Technical Reports Server (NTRS)

    Ortega, R.

    1995-01-01

    An ANSYS finite-element code routine to check for duplicated elements within the volume of a three-dimensional (3D) finite-element mesh was developed. The routine developed is used for checking floating elements within a mesh, identically duplicated elements, and intersecting elements with a common face. A space shuttle main engine alternate turbopump development high pressure oxidizer turbopump finite-element model check using the developed subroutine is discussed. Finally, recommendations are provided for duplicate element checking of 3D finite-element models.

  3. Double-outlet right ventricle with absent left ventricle and mitral atresia in a fetus with a deletion 22q12.

    PubMed

    L'herminé-Coulomb, Aurore; Houyel, Lucille; Aboura, Azzedine; Audibert, François; Dal Soglio, Dorothée; Tachdjian, Gérard

    2004-09-01

    Interstitial deletions of chromosomal region 22q12 are rare. We report the prenatal diagnosis of a de novo interstitial deletion 22q12. The fetus was karyotyped because of a complex cardiac anomaly. Conventional and molecular cytogenetics showed a female karyotype with a de novo pericentric inversion of one chromosome 22 associated with a deletion of the chromosomal region 22q12 leading to a partial monosomy 22q12. At autopsy, the fetus showed double-outlet right ventricle (DORV) with absent left ventricle and mitral atresia. This observation suggests that one or several genes for the early looping step of heart development may reside in chromosomal region 22q12. Further studies are needed to identify these genes, and to search microdeletions of 22q12 region in patients with DORV. Copyright (c) 2004 John Wiley & Sons, Ltd.

  4. Four-dimensional functional analysis of left and right ventricles using MR images and active appearance models

    NASA Astrophysics Data System (ADS)

    Zhang, Honghai; Thomas, Matthew T.; Walker, Nicholas E.; Stolpen, Alan H.; Wahle, Andreas; Scholz, Thomas D.; Sonka, Milan

    2007-03-01

    Conventional analysis of cardiac ventricular function from magnetic resonance images is typically relying on short axis image information only. Usually, two cardiac phases of the cardiac cycle are analyzed- the end-diastole and end-systole. Unfortunately, the short axis ventricular coverage is incomplete and inconsistent due to the lack of image information about the ventricular apex and base. In routine clinical images, this information is only available in long axis image planes. Additionally, the standard ventricular function indices such as ejection fraction are only based on a limited temporal information and therefore do not fully describe the four-dimensional (4D, 3D+time) nature of the heart's motion. We report a novel approach in which the long and short axis image data are fused to correct for respiratory motion and form a spatio-temporal 4D data sequence with cubic voxels. To automatically segment left and right cardiac ventricles, a 4D active appearance model was built. Applying the method to cardiac segmentation of tetralogy of Fallot (TOF) and normal hearts, our method achieved mostly subvoxel signed surface positioning errors of 0.2+/-1.1 voxels for normal left ventricle, 0.6+/-1.5 voxels for normal right ventricle, 0.5+/-2.1 voxels for TOF left ventricle, and 1.3+/-2.6 voxels for TOF right ventricle. Using the computer segmentation results, the cardiac shape and motion indices and volume-time curves were derived as novel indices describing the ventricular function in 4D.

  5. Oxidative status and chymotrypsin-like activity in right and left ventricle hypertrophy in an experimental model of emphysema.

    PubMed

    Tonon, Jair; Guarnier, Flávia Alessandra; Brunnquell, Cláudia Roberta; Bernardes, Sara Santos; Cecchini, Alessandra Lourenço; Cecchini, Rubens

    2013-09-01

    Although cardiac muscle hypertrophy has been studied in association with several diseases, its mechanism in patients with emphysema, in particular in relation to oxidative stress and proteolysis, remains unknown. The role of oxidative stress and proteolysis in right and left ventricle hypertrophy was investigated in hamsters with emphysema induced by 2 different doses of papain (20mg/mL, E20 and 40mg/mL, E40). The thickness of the ventricles, total and cardiac weight, lipid peroxidation, carbonyl proteins, total antioxidant capacity (TAC), and proteasomal proteolytic activity were evaluated in the right ventricle (RV) and the left ventricle (LV) of control and emphysema hamsters. RV thickness was increased by 12% in the E20 group and by 29% in the E40 group. Lipid peroxidation measured by chemiluminescence was increased in the E40 group (from 3350.68±392.44URL/g tissue to 4696.63±1076.70URL/g tissue, p<0.05). TAC also increased only in the E40 group. In the LV, chemiluminescence values increased from 4044.77±503.39 to 5517.10±388.27 in the E20 group and to 8169.14±1748.77URL/g tissue in the E40 group (p<0.05, both). TAC significantly increased in the E20 and E40 groups. No differences were detected in substances reactive to thiobarbituric acid or carbonyl proteins when comparing ventricles or doses. Chymotrypsin-like proteolytic activity significantly decreased in both groups and ventricles. Emphysema can induce right and left ventricle lipid peroxidation and result in antioxidant mobilization. These data together support the idea that cardiac hypertrophy in response to emphysema is mediated in part by proteolytic pathways with involvement of reactive species. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  6. Finite element coiled cochlea model

    NASA Astrophysics Data System (ADS)

    Isailovic, Velibor; Nikolic, Milica; Milosevic, Zarko; Saveljic, Igor; Nikolic, Dalibor; Radovic, Milos; Filipović, Nenad

    2015-12-01

    Cochlea is important part of the hearing system, and thanks to special structure converts external sound waves into neural impulses which go to the brain. Shape of the cochlea is like snail, so geometry of the cochlea model is complex. The simplified cochlea coiled model was developed using finite element method inside SIFEM FP7 project. Software application is created on the way that user can prescribe set of the parameters for spiral cochlea, as well as material properties and boundary conditions to the model. Several mathematical models were tested. The acoustic wave equation for describing fluid in the cochlea chambers - scala vestibuli and scala timpani, and Newtonian dynamics for describing vibrations of the basilar membrane are used. The mechanical behavior of the coiled cochlea was analyzed and the third chamber, scala media, was not modeled because it does not have a significant impact on the mechanical vibrations of the basilar membrane. The obtained results are in good agreement with experimental measurements. Future work is needed for more realistic geometry model. Coiled model of the cochlea was created and results are compared with initial simplified coiled model of the cochlea.

  7. Evaluation of variability of phase indices of the left ventricle in the course of time.

    PubMed

    Emer, Ozdes; Karacalioglu, Alper O; Gursoy, Erol; Ince, Semra

    2014-11-01

    Since the effect of time on phase indices is still unclear, the aim of the study was to evaluate the variability of phase indices of the left ventricle which were derived from stress and rest single-photon emission computed tomography (SPECT) imaging acquired at early and late times. One hundred twenty-one patients (72 men, 49 women) were included into the study. All stress and rest gated myocardial perfusion imaging (gMPI) acquisitions were acquired at two different time points as early in 15 ± 5 min and late in 45 ± 5 min. The peak of the phase histogram (PP), the standard deviation of the phase distribution (SDPH), the width of the band (BPH), and the symmetry (histogram skewness, HS) and peakedness of the phase histogram (histogram kurtosis, HK) which are the parameters for assessing left ventricular systolic dyssynchrony were calculated in all stress and rest SPECT images acquired twice. The phase indices derived from the late rest scans were smaller than those of the early rest scans but, the differences were not significant. When considering the comparisons of phase indices derived from two different time points after stress, PP showed a tendency to decrease (from 160.8 ± 18.3 to 152.5 ± 17.3; p < 0.001) over time but SDPH (from 20.2 ± 10.6 to 22.4 ± 12.2; p = 0.018) and BPH (from 61.5 ± 36.0 to 66.3 ± 37.3; p = 0.045) tended to increase over time. When the post-stress and the resting dyssynchrony parameters derived at two different time points were compared to each other; PP decreased at early and late times approximately 12 and 9 %, respectively, SDPH increased at early and late times approximately 28.5 and 14 %, respectively, and BPH increased at early and late times approximately 23 and 12 %, respectively. In resting conditions, phase indices of the left ventricle, and therefore, the phase histogram tend to remain constant over time but, in conditions after exercise, the phase histogram tend to be long and narrow due to

  8. Post myocardial infarction of the left ventricle: the course ahead seen by cardiac MRI

    PubMed Central

    Masci, Pier Giorgio

    2012-01-01

    In the last decades, cardiac magnetic resonance imaging (MRI) has gained acceptance in cardiology community as an accurate and reproducible diagnostic imaging modality in patients with ischemic heart disease (IHD). In particular, in patients with acute myocardial infarction (MI) cardiac MRI study allows a comprehensive assessment of the pattern of ischemic injury in term of reversible and irreversible damage, myocardial hemorrhage and microvascular obstruction (MVO). Myocardial salvage index, derived by quantification of myocardium (area) at risk and infarction, has become a promising surrogate end-point increasingly used in clinical trials testing novel or adjunctive reperfusion strategies. Early post-infarction, the accurate and reproducible quantification of myocardial necrosis, along with the characterization of ischemic myocardial damage in its diverse components, provides important information to predict post-infarction left ventricular (LV) remodeling, being useful for patients stratification and management. Considering its non-invasive nature, cardiac MRI suits well for investigating the time course of infarct healing and the changes occurring in peri-infarcted (adjacent) and remote myocardium, which ultimately promote the geometrical, morphological and functional abnormalities of the entire left ventricle (global LV remodeling). The current review will focus on the cardiac MRI utility for a comprehensive evaluation of patients with acute and chronic IHD with particular regard to post-infarction remodeling. PMID:24282705

  9. Sequential functional analysis of left ventricle from 2D-echocardiography images.

    PubMed

    Chacko, Rani; Singh, Megha

    2014-06-01

    The sequential changes in shape of left ventricle (LV), which are the result of cellular interactions and their levels of organizational complexity, in its long axis view during one cardiac cycle are obtained. The changes are presented in terms of shape descriptors by processing of images obtained from a normal subject and two patients with dilated left ventricular cardio-myopathy. These images are processed, frame by frame, by a semi-automatic algorithm developed by MATLAB. This is consisting of gray scale conversion, the LV contour extraction by application of median and SRAD filters, and morphological operations. By filling the identified region with pixels and number of pixels along its contour the area and perimeter are calculated, respectively. From these the changes in LV volume and shape index are calculated. Based on these the stroke volume (SV) and ejection fraction (EF) are calculated. The changes in LV area, perimeter, volume and shape index in cardiac patients are less than that of normal subject. The calculated SV and EF of normal subject are within the range as obtained by various imaging procedures.

  10. Syndromic non-compaction of the left ventricle: associated chromosomal anomalies.

    PubMed

    Digilio, M C; Bernardini, L; Gagliardi, M G; Versacci, P; Baban, A; Capolino, R; Dentici, M L; Roberti, M C; Angioni, A; Novelli, A; Marino, B; Dallapiccola, B

    2013-10-01

    Non-compaction of the left ventricle (NCLV) is a cardiomyopathy characterized by prominent left ventricular trabeculae and deep intertrabecular recesses. Associated extracardiac anomalies occur in 14-66% of patients of different series, while chromosomal anomalies were reported in sporadic cases. We investigated the prevalence of chromosomal imbalances in 25 syndromic patients with NCLV, using standard cytogenetic, subtelomeric fluorescent in situ hybridization, and array-comparative genomic hybridization (CGH) analyses. Standard chromosome analysis disclosed an abnormality in three (12%) patients, including a 45,X/46,XX mosaic, a 45,X/46,X,i(Y)(p11) mosaic, and a de novo Robertsonian 13;14 translocation in a child affected by hypomelanosis of Ito. Cryptic chromosome anomalies were found in six (24%) cases, including 1p36 deletion in two patients, 7p14.3p14.1 deletion, 18p subtelomeric deletion, 22q11.2 deletion associated with velo-cardio-facial syndrome, and distal 22q11.2 deletion, each in one case. These results recommend accurate clinical evaluation of patients with NCLV, and suggest that chromosome anomalies occur in about one third of syndromic NCLV individuals, without metabolic/neuromuscular disorder. Array-CGH analysis should be included in the diagnostic protocol of these patients, because different submicroscopic imbalances are causally associated with this disorder and can pinpoint candidate genes for this cardiomyopathy. © 2012 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  11. Convolutional neural network regression for short-axis left ventricle segmentation in cardiac cine MR sequences.

    PubMed

    Tan, Li Kuo; Liew, Yih Miin; Lim, Einly; McLaughlin, Robert A

    2017-07-01

    Automated left ventricular (LV) segmentation is crucial for efficient quantification of cardiac function and morphology to aid subsequent management of cardiac pathologies. In this paper, we parameterize the complete (all short axis slices and phases) LV segmentation task in terms of the radial distances between the LV centerpoint and the endo- and epicardial contours in polar space. We then utilize convolutional neural network regression to infer these parameters. Utilizing parameter regression, as opposed to conventional pixel classification, allows the network to inherently reflect domain-specific physical constraints. We have benchmarked our approach primarily against the publicly-available left ventricle segmentation challenge (LVSC) dataset, which consists of 100 training and 100 validation cardiac MRI cases representing a heterogeneous mix of cardiac pathologies and imaging parameters across multiple centers. Our approach attained a .77 Jaccard index, which is the highest published overall result in comparison to other automated algorithms. To test general applicability, we also evaluated against the Kaggle Second Annual Data Science Bowl, where the evaluation metric was the indirect clinical measures of LV volume rather than direct myocardial contours. Our approach attained a Continuous Ranked Probability Score (CRPS) of .0124, which would have ranked tenth in the original challenge. With this we demonstrate the effectiveness of convolutional neural network regression paired with domain-specific features in clinical segmentation. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. [Electrovectorcardiographic aspects of systolic and diastolic overloads of the left ventricle].

    PubMed

    de Micheli, A; Medrano, G A; Casanova, J M

    1990-01-01

    Electrovectorcardiographic features of the ventricular depolarization and repolarization related to hemodynamic conditions were studied in typical cases of left ventricular systolic and diastolic overloads. Electrovectorcardiographic exploration was effected prospectively in 70 subjects with aortic coarctation (52 men and 18 women) and in 90 with patent ductus arteriosus (18 men and 72 women). Fifty-five subjects of the series with systolic overload (A) and sixty-five with diastolic overload (B) underwent surgical treatment. In all cases, high fidelity tracings were obtained by means of a VR-6 polygraph: standard leads, unipolar limb leads, thoracic and precordial unipolar leads from V7R to V7 or V8, high abdominal leads MD, ME, MI and, when it was possible, the corresponding intraventricular unipolar leads. Vectorcardiographic curves were recorded in three planes by Grishman's cube method and photographed using the polaroid system. In both series, ventricular conduction disturbances of proximal or peripheral types were observed. These seem to be independent of hemodynamic conditions. In the presence of aortic coarctation as well as of patent ductus arteriosus, the Q-Tc interval can be prolonged in all leads, probably owing to electrolytic disorders, or in left leads only as a reflection of elevated telediastolic pressure in the ipsilateral ventricle.

  13. Intraventricular filling in physical models of the left ventricle: influence of aortic pressure

    NASA Astrophysics Data System (ADS)

    Nelsen, Nicholas; Samaee, Milad; Santhanakrishnan, Arvind

    2016-11-01

    Clinical studies using medical imaging have provided evidence on the formation of an intraventricular vortex in the left ventricle (LV) during diastolic phase of the cardiac cycle. However, the question of how the vortex characteristics are altered with aortic pressure remains unclear. This is of relevance to hypertensive heart disease and heart failure with normal ejection fraction. Using an experimental left heart simulator, we have previously shown that increasing LV wall stiffness results in reduction of the filling vortex circulation. In this study, we investigate the effects of varying aortic pressure in addition to wall stiffness. A series of flexible-walled LV models with varying wall stiffness were tested in a pulsatile flow loop. 2D particle image velocimetry was used to visualize intraventricular flow and calculate filling vortex circulation. The flow circuit was first setup with the least stiffness LV physical model, and tuned to physiological aortic pressure, cardiac output and ejection fraction. We then iteratively tested LV models with increasing stiffness without changing circuit variables. Comparisons of the filling vortex circulation with changing aortic pressure relative to the baseline and increased LV stiffness models will be presented.

  14. Natural history and patterns of recovery of contractile function in single left ventricle after Fontan operation.

    PubMed

    Sluysmans, T; Sanders, S P; van der Velde, M; Matitiau, A; Parness, I A; Spevak, P J; Mayer, J E; Colan, S D

    1992-12-01

    Before the era of the Fontan procedure, the typical course of patients with single left ventricle (LV) consisted of heart failure and death during the second or third decade of life. Despite the advent of effective palliative therapy, ventricular dysfunction remains a significant clinical problem for these patients. To investigate the causes of ventricular dysfunction in these patients and to determine whether Fontan-type repair reverses deterioration of LV function, the ventricular dimensions, volume, shape, wall stress, and systolic function were determined by echocardiography in 84 patients 0.2-35 years old with double-inlet single LV or tricuspid atresia. Measurements were obtained in 67 patients after palliation (arterial shunt or pulmonary artery band) and in 47 patients a median of 4.4 years after a Glenn (n = 9) or a Fontan operation (n = 38). Before a Fontan procedure, ventricular volumes were 2 to 3 times normal. Ventricular afterload, assessed as circumferential and meridional end-systolic wall stress, became abnormal after 2 years of age. With age, LV shape changed progressively from ellipsoidal to spherical, as indicated by the decrease in long axis:short axis ratio from normal (1.9) toward unity. Concomitantly, the ratio of circumferential to meridional end-systolic wall stress fell from 1.3 to unity, the ratio of a sphere at equilibrium. This age-related change in shape and load occurred in concert with progressive deterioration of LV systolic function and contractility. Aortic oxygen saturation, an indicator of pulmonary blood flow and therefore volume work in single-ventricle physiology, was inversely and independently correlated with contractility. In the group of patients in whom a Glenn or a Fontan operation was performed at < 10 years of age, ventricular dimensions, volumes, and wall stress diminished and LV function and contractility improved after surgery (p < 0.001). In patients undergoing surgery after 10 years of age, few had improvement

  15. Mapping of left ventricle wall thickness in mice using 11.7-T magnetic resonance imaging.

    PubMed

    Saito, Shigeyoshi; Masuda, Kasumi; Mori, Yuki; Nakatani, Satoshi; Yoshioka, Yoshichika; Murase, Kenya

    2017-02-01

    The left ventricle (LV) wall thickness is an important and routinely measured cardiologic parameter. Here we introduce three-dimensional (3D) mapping of LV wall thickness and function using a self-gated magnetic resonance (MR) sequence for ultra-high-field 11.7-T MR cine imaging of mouse hearts. Six male C57BL/6-j mice were subjected to 11.7-T MR imaging (MRI). Three standard views-short axis, long axis four-chamber, and long axis two-chamber-and eight consecutive short axis scans from the apex to base were performed for each mouse. The resulting 11 self-gated cine images were used for fast low-angle shot analysis with a navigator echo over an observation period of approximately 35min. The right ventricle (RV) and LV were identified in the short axis and four-chamber views. On 3D color-coded maps, the interventricular septum wall (diastole: 0.94±0.05mm, systole: 1.20±0.09mm) and LV free wall (diastole: 1.07±0.15mm, systole: 1.79±0.11mm) thicknesses were measured. This 3D wall thickness mapping technique can be used to observe regional wall thickness at the end-diastole and end-systole. Self-gated cine imaging based on ultra-high-field MRI can be used to accurately and easily measure cardiac function and wall thickness in normal mouse hearts. As in the preclinical study, this versatile and simple method will be clinically useful for the high-field-MRI evaluation of cardiac function and wall thickness. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Novel measurement setup for evaluation of left ventricle motion and strain tracking methods

    NASA Astrophysics Data System (ADS)

    Leśniak-Plewińska, Beata; Żmigrodzki, Jakub; Cygan, Szymon; KałuŻyński, Krzysztof

    2017-03-01

    Cardiac strain quantification using ultrasound is an active area of research. Physical left ventricle (LV) model play a significant role in the evaluation and development of myocardium strain imaging techniques. Several LV models have been reported. In spite of increasing interest in LV twist, only one of them implements torsional deformation, but it does not allow long axis views. This work presents a novel prototype of physical LV model and dedicated measurement setup which do not have this limitation. The model was made of Poly(vinyl alcohol) cryogel (PVA-c). The solution for the chamber part was doped with scattering particles to imitate the echogenicity of myocardium and to facilitate automatic segmentation of the chamber wall. The model was mounted in a measurement setup allowing computer controlled linear motion of the basis, rotation of the apex and inflation of the ventricle and the use both ultrasound imaging planes: short (SAX) and long axis (LAX). During preliminary tests RF signals as well as B-mode and M-mode images were acquired. Experiment results confirmed the possibility of forcing controlled deformation of the presented LV model wall, including elongation/shortening in the long axis direction and twist around this axis. In consequence, the model can mimic deformations of the LV wall to a large extent. The chamber wall can be segmented in B-mode images in both projections. The model with the measurement setup may be used in development and validation of a wide range of echocardiographic diagnostic procedures including segmentation, strain estimation and 3D data processing.

  17. Finite-Element Composite-Analysis Program

    NASA Technical Reports Server (NTRS)

    Bowles, David E.

    1990-01-01

    Finite Element Composite Analysis Program, FECAP, special-purpose finite-element program for analyzing behavior of composite material with microcomputer. Procedure leads to set of linear simultaneous equations relating unknown nodal displacement to applied loads. Written in HP BASIC 3.0.

  18. Finite element analysis of helicopter structures

    NASA Technical Reports Server (NTRS)

    Rich, M. J.

    1978-01-01

    Application of the finite element analysis is now being expanded to three dimensional analysis of mechanical components. Examples are presented for airframe, mechanical components, and composite structure calculations. Data are detailed on the increase of model size, computer usage, and the effect on reducing stress analysis costs. Future applications for use of finite element analysis for helicopter structures are projected.

  19. Nonlinear finite element modeling of corrugated board

    Treesearch

    A. C. Gilchrist; J. C. Suhling; T. J. Urbanik

    1999-01-01

    In this research, an investigation on the mechanical behavior of corrugated board has been performed using finite element analysis. Numerical finite element models for corrugated board geometries have been created and executed. Both geometric (large deformation) and material nonlinearities were included in the models. The analyses were performed using the commercial...

  20. 3-D Finite Element Code Postprocessor

    SciTech Connect

    1996-07-15

    TAURUS is an interactive post-processing application supporting visualization of finite element analysis results on unstructured grids. TAURUS provides the ability to display deformed geometries and contours or fringes of a large number of derived results on meshes consisting of beam, plate, shell, and solid type finite elements. Time history plotting is also available.

  1. The Effects of Training on the Time Components of the Left Ventricle, and Cardiac Time Components: Sedentary versus Active Individuals.

    ERIC Educational Resources Information Center

    Plowman, Sharon Ann

    A review of previous research was completed to determine (a) the response of the cardiac time components of the left ventricle to varying types and intensities of training programs, (b) the probable physiological explanations for these responses, and (c) the significance of the changes which did or did not occur. It was found that, at rest,…

  2. Analysis of the Influence of the Electrical Asynchrony on Regional Mechanics of the Infarcted Left Ventricle Using Electromechanical Heart Models

    NASA Astrophysics Data System (ADS)

    Liu, Feng; Xia, Ling; Zhang, Xin

    Asynchronous electrical activation, as induced by myocardial infarction, causes various abnormalities in left ventricle function. The influence of the electrical asynchrony on regional mechanics of the left ventricle is simulated using a mechanical heart model and an electrical heart model. The mechanical model accounts for the ventricular geometry, the fiber nature of the myocardial tissue, and the dependency of the activation sequence of the ventricular wall. The electrical model is based on a heart-torso model with realistic geometry, and different action potential waveforms with variables in duration are used to simulate the abnormal electrical activation after myocardial infarction. Regional deformation, strain and stress are calculated during systole phase. The preliminary results show that asynchronous electrical activation, as an important factor, significantly affects regional mechanical performance of the infarcted left ventricle, it indicates heterogeneous contraction pattern and elevated systolic stresses near the injured region. The simulated results are compared with solutions obtained in the literature. This simulation suggests that such coupled heart models can be used to assess the mechanical function of the left ventricle with diseases such as myocardial infarction, and more realistic models of cardiac function are essential for clinical evaluation of heart disease.

  3. [Association of Wolff-Parkinson-White syndrome with isolated non-compaction of the left ventricle: a case report].

    PubMed

    Brembilla-Perrot, B; Codreanu, A; Marie, P Y; Beurrier, D; Husson, J L; Hutin, O; Pruna, A; Yangni N'Da, O; Ernst, Y; Bosser, G

    2006-06-01

    The Wolff-Parkinson-White syndrome (WPW) may be associated with a number of cardiac pathologies, especially congenital disease, in 7.5 to 17% of cases. The authors report a rare association of the WPW syndrome with two Kent bundles, right and left septal, with non-compaction of the left ventricle in a 52 year old man. This was a chance finding during systematic echocardiography after ablation, and confirmed by cardiac MRI. The patient was asymptomatic.

  4. Statistical shape modeling of the left ventricle: myocardial infarct classification challenge.

    PubMed

    Suinesiaputra, Avan; Ablin, Pierre; Alba, Xenia; Alessandrini, Martino; Allen, Jack; Bai, W; Cimen, Serkan; Claes, Peter; Cowan, Brett R; D'hooge, Jan; Duchateau, Nicolas; Ehrhardt, Jan; Frangi, Alejandro F; Gooya, Ali; Grau, Vicente; Lekadir, Karim; Lu, Allen; Mukhopadhyay, Anirban; Oksuz, Ilkay; Pennec, Xavier; Pereanez, Marco; Pinto, Catarina; Piras, Paolo; Rohe, Marc-Michel; Rueckert, Daniel; Sermesant, Maxime; Siddiqi, Kaleem; Tabassian, Mahdi; Teresi, Luciano; Tsaftaris, Sotirios A; Wilms, Matthias; Young, Alistair A; Zhang, Xingyu; Medrano-Gracia, Pau

    2017-01-17

    Statistical shape modeling is a powerful tool for visualizing and quantifying geometric and functional patterns of the heart. After myocardial infarction (MI), the left ventricle typically remodels in response to physiological challenges. Several methods have been proposed in the literature to describe statistical shape changes. Which method best characterizes left ventricular remodeling after MI is an open research question. A better descriptor of remodeling is expected to provide a more accurate evaluation of disease status in MI patients. We therefore designed a challenge to test shape characterization in MI given a set of three-dimensional left ventricular surface points. The training set comprised 100 MI patients, and 100 asymptomatic volunteers (AV). The challenge was initiated in 2015 at the Statistical Atlases and Computational Models of the Heart workshop, in conjunction with the MICCAI conference. The training set with labels was provided to participants, who were asked to submit the likelihood of MI from a different (validation) set of 200 cases (100 AV and 100 MI). Sensitivity, specificity, accuracy and area under the receiver operating characteristic curve were used as the outcome measures. The goals of this challenge were to (1) establish a common dataset for evaluating statistical shape modeling algorithms in MI, and (2) test whether statistical shape modeling provides additional information characterizing MI patients over standard clinical measures. Eleven groups with a wide variety of classification and feature extraction approaches participated in this challenge. All methods achieved excellent classification results with accuracy ranges from 0.83 to 0.98. The areas under the receiver operating characteristic curves were all above 0.90. Four methods showed significantly higher performance than standard clinical measures. The dataset and software for evaluation are available from the Cardiac Atlas Project website1.

  5. Simulated Microgravity and Recovery-Induced Remodeling of the Left and Right Ventricle

    PubMed Central

    Zhong, Guohui; Li, Yuheng; Li, Hongxing; Sun, Weijia; Cao, Dengchao; Li, Jianwei; Zhao, Dingsheng; Song, Jinping; Jin, Xiaoyan; Song, Hailin; Yuan, Xinxin; Wu, Xiaorui; Li, Qi; Xu, Qing; Kan, Guanghan; Cao, Hongqing; Ling, Shukuan; Li, Yingxian

    2016-01-01

    Physiological adaptations to microgravity involve alterations in cardiovascular systems. These adaptations result in cardiac remodeling and orthostatic hypotension. However, the response of the left ventricle (LV) and right ventricle (RV) following hindlimb unloading (HU) and hindlimb reloading (HR) is not clear and the underlying mechanism remains to be understood. In this study, three groups of mice were subjected to HU by tail suspension for 28 days. Following this, two groups were allowed to recover for 7 or 14 days. The control group was treated equally, with the exception of tail suspension. Echocardiography was performed to detect the structure and function changes of heart. Compared with the control, the HU group of mice showed reduced LV-EF (ejection fraction), and LV-FS (fractional shortening). However, mice that were allowed to recover for 7 days after HU (HR-7d) showed increased LVIDs (systolic LV internal diameter) and LV Vols (systolic LV volume). Mice that recovered for 14 days (HR-14d) returned to the normal state. In comparison, RV-EF and RV-FS didn't recover to the normal conditions till being reloaded for 14 days. Compared with the control, RVIDd (diastolic RV internal diameter), and RV Vold (diastolic RV volume) were reduced in HU group and recovered to the normal conditions in HR-7d and HR-14d groups, in which groups RVIDs (systolic RV internal diameter) and RV Vols (systolic RV volume) were increased. Histological analysis and cardiac remodeling gene expression results indicated that HU induces left and right ventricular remodeling. Western blot demonstrated that the phosphorylation of HDAC4 and ERK1/2 and the ratio of LC3-II / LC3-I, were increased following HU and recovered following HR in both LV and RV, and the phosphorylation of AMPK was inhibited in both LV and RV following HU, but only restored in LV following HR for 14 days. These results indicate that simulated microgravity leads to cardiac remodeling, and the remodeling changes can

  6. Tyrosine hydroxylase phosphorylation after naloxone-induced morphine withdrawal in the left ventricle.

    PubMed

    Almela, Pilar; Victoria Milanés, Maria; Luisa Laorden, Maria

    2009-07-01

    Our previous studies have shown that morphine withdrawal induced hyperactivity of cardiac noradrenergic pathways. The purpose of the present study was to evaluate the effects of morphine withdrawal on site-specific tyrosine hydroxylase (TH) phosphorylation in the rat left ventricle. Dependence on morphine was induced by a 7-day s.c. implantation of morphine pellets. Morphine withdrawal was precipitated on day 8 by an injection of naloxone (2 mg/kg, s.c.). TH phosphorylation was determined by quantitative blot immunolabelling using phosphorylation state-specific antibodies. Ninety min after naloxone administration to morphine-dependent rats there was an increase in phospho-Ser40-TH (139.0 +/- 13%, P < 0.05) and Ser31-TH (135.5 +/- 11%, P < 0.05) in the left ventricle which is associated with both an increase in total TH levels (114.4 +/- 4.6%, P < 0.05, P < 0.01) and an enhancement of TH activity (51.0 +/- 11 dm/microg protein, P < 0.001). When HA-1004 (40 nmol/day), inhibitor of cyclic AMP dependent protein kinase (PKA) was infused, concomitantly with morphine, it diminished the increase in noradrenaline (NA) turnover, total TH expression (95.76 +/- 4.1 %, P < 0.01) and TH phosphorylation at Ser40 (85.5 +/- 11%, P < 0.01) in morphine-withdrawn rats. In addition, we showed that the ability of morphine withdrawal to stimulate phosphorylation at serine 31 is reduced (101.7 +/- 7.7%, P < 0.05) by SL327 (100 mg/kg, i.p.), an inhibitor of extracellular signal-regulated kinase (ERK) activation. The present findings demonstrate that the enhancement of total TH expression and the increase of the phosphorylation state of TH during morphine withdrawal are dependent on PKA and ERK and suggest that these transduction pathways might contribute to the activation of the cardiac catecholaminergic neurons in response to morphine- withdrawal.

  7. Simulated Microgravity and Recovery-Induced Remodeling of the Left and Right Ventricle.

    PubMed

    Zhong, Guohui; Li, Yuheng; Li, Hongxing; Sun, Weijia; Cao, Dengchao; Li, Jianwei; Zhao, Dingsheng; Song, Jinping; Jin, Xiaoyan; Song, Hailin; Yuan, Xinxin; Wu, Xiaorui; Li, Qi; Xu, Qing; Kan, Guanghan; Cao, Hongqing; Ling, Shukuan; Li, Yingxian

    2016-01-01

    Physiological adaptations to microgravity involve alterations in cardiovascular systems. These adaptations result in cardiac remodeling and orthostatic hypotension. However, the response of the left ventricle (LV) and right ventricle (RV) following hindlimb unloading (HU) and hindlimb reloading (HR) is not clear and the underlying mechanism remains to be understood. In this study, three groups of mice were subjected to HU by tail suspension for 28 days. Following this, two groups were allowed to recover for 7 or 14 days. The control group was treated equally, with the exception of tail suspension. Echocardiography was performed to detect the structure and function changes of heart. Compared with the control, the HU group of mice showed reduced LV-EF (ejection fraction), and LV-FS (fractional shortening). However, mice that were allowed to recover for 7 days after HU (HR-7d) showed increased LVIDs (systolic LV internal diameter) and LV Vols (systolic LV volume). Mice that recovered for 14 days (HR-14d) returned to the normal state. In comparison, RV-EF and RV-FS didn't recover to the normal conditions till being reloaded for 14 days. Compared with the control, RVIDd (diastolic RV internal diameter), and RV Vold (diastolic RV volume) were reduced in HU group and recovered to the normal conditions in HR-7d and HR-14d groups, in which groups RVIDs (systolic RV internal diameter) and RV Vols (systolic RV volume) were increased. Histological analysis and cardiac remodeling gene expression results indicated that HU induces left and right ventricular remodeling. Western blot demonstrated that the phosphorylation of HDAC4 and ERK1/2 and the ratio of LC3-II / LC3-I, were increased following HU and recovered following HR in both LV and RV, and the phosphorylation of AMPK was inhibited in both LV and RV following HU, but only restored in LV following HR for 14 days. These results indicate that simulated microgravity leads to cardiac remodeling, and the remodeling changes can

  8. [Topography of the contours of the inner surface of the wall of the left ventricle of the heart in systole].

    PubMed

    Uglov, F G; Zubtsovskiĭ, V N; Bol'shakov, O P; Mursalova, F A; Tarasov, A N

    1984-09-01

    Chosen at random 38 diastolic preparations of human hearts from persons having not any cardiac pathology, as demonstrate the postmortem examination, have been investigated. The left ventricle casts have been made during the first 24 hours after death according to a strictly fixed technique by means of filling the cardiac chambers with polymere mass--protacryl--under a physiological pressure of the diastolic filling. The trabecules are arranged as a spiral from the apex of the ventricle up to the atrioventricular fibrous ring, with approaching the apex the spiral step increases and the trabecules straighten. The left ventricle cast is devided into some planes, the envelopes and the trabecularity lines are measured. Average values of the shift in the trabecularity lines I, II, III and in the cross sections B, C, D, E are defined in relation to the plane A and in every case in relation to the previous plane Cn-1. The data obtained are presented in tables and diagrams. The greatest shift demonstrate the trabecularity lines I running predominantly along the posterior wall of the left ventricle in the planes B and which are situated nearer to the atrioventricular ring projection. Owing to the presence of the spiral-shaped course of the trabecules, it is possible to suppose that it influences the blood stream twisting clockwise in the left ventricle during the diastole phase. This indicates the necessity to work out some new constructions of artificial cardiac valves, securing the twisted blood stream. The condition mentioned should be taken into consideration while making prostheses of the cardiac valves.

  9. Flow dynamics and energy efficiency of flow in the left ventricle during myocardial infarction.

    PubMed

    Vasudevan, Vivek; Low, Adriel Jia Jun; Annamalai, Sarayu Parimal; Sampath, Smita; Poh, Kian Keong; Totman, Teresa; Mazlan, Muhammad; Croft, Grace; Richards, A Mark; de Kleijn, Dominique P V; Chin, Chih-Liang; Yap, Choon Hwai

    2017-03-31

    Cardiovascular disease is a leading cause of death worldwide, where myocardial infarction (MI) is a major category. After infarction, the heart has difficulty providing sufficient energy for circulation, and thus, understanding the heart's energy efficiency is important. We induced MI in a porcine animal model via circumflex ligation and acquired multiple-slice cine magnetic resonance (MR) images in a longitudinal manner-before infarction, and 1 week (acute) and 4 weeks (chronic) after infarction. Computational fluid dynamic simulations were performed based on MR images to obtain detailed fluid dynamics and energy dynamics of the left ventricles. Results showed that energy efficiency flow through the heart decreased at the acute time point. Since the heart was observed to experience changes in heart rate, stroke volume and chamber size over the two post-infarction time points, simulations were performed to test the effect of each of the three parameters. Increasing heart rate and stroke volume were found to significantly decrease flow energy efficiency, but the effect of chamber size was inconsistent. Strong complex interplay was observed between the three parameters, necessitating the use of non-dimensional parameterization to characterize flow energy efficiency. The ratio of Reynolds to Strouhal number, which is a form of Womersley number, was found to be the most effective non-dimensional parameter to represent energy efficiency of flow in the heart. We believe that this non-dimensional number can be computed for clinical cases via ultrasound and hypothesize that it can serve as a biomarker for clinical evaluations.

  10. Early diastolic clicks after the Fontan procedure for double inlet left ventricle: anatomical and physiological correlates.

    PubMed Central

    Redington, A N; Chan, K Y; Carvalho, J S; Shinebourne, E A

    1990-01-01

    M mode echocardiograms and simultaneous phonocardiograms were recorded in four patients with early diastolic clicks on auscultation. All had double inlet left ventricle and had undergone the Fontan procedure with closure of the right atrioventricular valve orifice by an artificial patch. The phonocardiogram confirmed a high frequency sound occurring 60-90 ms after aortic valve closure and coinciding with the time of maximal excursion of the atrioventricular valve patch towards the ventricular mass. One patient had coexisting congenital complete heart block. The M mode echocardiogram showed "reversed" motion of the patch towards the right atrium during atrial contraction. Doppler flow studies showed that coincident with this motion there was forward flow in the pulmonary artery with augmentation when atrial contraction coincided with ventricular systole. The early diastolic click in these patients was explained by abrupt cessation of the motion of the atrioventricular valve patch towards the ventricular mass in early diastole. In one patient atrial contraction led to a reversal of this motion and was associated with forward flow in the pulmonary artery. Images PMID:2278802

  11. Cardiac cell culture model as a left ventricle mimic for cardiac tissue generation.

    PubMed

    Nguyen, Mai-Dung; Tinney, Joseph P; Yuan, Fangping; Roussel, Thomas J; El-Baz, Ayman; Giridharan, Guruprasad; Keller, Bradley B; Sethu, Palaniappan

    2013-09-17

    A major challenge in cardiac tissue engineering is the delivery of hemodynamic mechanical cues that play a critical role in the early development and maturation of cardiomyocytes. Generation of functional cardiac tissue capable of replacing or augmenting cardiac function therefore requires physiologically relevant environments that can deliver complex mechanical cues for cardiomyocyte functional maturation. The goal of this work is the development and validation of a cardiac cell culture model (CCCM) microenvironment that accurately mimics pressure-volume changes seen in the left ventricle and to use this system to achieve cardiac cell maturation under conditions where mechanical loads such as pressure and stretch are gradually increased from the unloaded state to conditions seen in vivo. The CCCM platform, consisting of a cell culture chamber integrated within a flow loop was created to accomplish culture of 10 day chick embryonic ventricular cardiomyocytes subject to 4 days of stimulation (10 mmHg, ∼13% stretch at a frequency of 2 Hz). Results clearly show that CCCM conditioned cardiomyocytes accelerate cardiomyocyte structural and functional maturation in comparison to static unloaded controls as evidenced by increased proliferation, alignment of actin cytoskeleton, bundle-like sarcomeric α-actinin expression, higher pacing beat rate at lower threshold voltages, and increased shortening. These results confirm the CCCM microenvironment can accelerate immature cardiac cell structural and functional maturation for potential cardiac regenerative applications.

  12. In-vivo characterization of 2D residence time maps in the left ventricle

    NASA Astrophysics Data System (ADS)

    Rossini, Lorenzo; Martinez-Legazpi, Pablo; Bermejo, Javier; Benito, Yolanda; Alhama, Marta; Yotti, Raquel; Perez Del Villar, Candelas; Gonzalez-Mansilla, Ana; Barrio, Alicia; Fernandez-Aviles, Francisco; Shadden, Shawn; Del Alamo, Juan Carlos

    2014-11-01

    Thrombus formation is a multifactorial process involving biology and hemodynamics. Blood stagnation and wall shear stress are linked to thrombus formation. The quantification of residence time of blood in the left ventricle (LV) is relevant for patients affected by ventricular contractility dysfunction. We use a continuum formulation to compute 2D blood residence time (TR) maps in the LV using in-vivo 2D velocity fields in the apical long axis plane obtained from Doppler-echocardiography images of healthy and dilated hearts. The TR maps are generated integrating in time an advection-diffusion equation of a passive scalar with a time-source term. This equation represents the Eulerian translation of DTR / D t = 1 and is solved numerically with a finite volume method on a Cartesian grid using an immersed boundary for the LV wall. Changing the source term and the boundary conditions allows us to track blood transport (direct and retained flow) in the LV and the topology of early (E) and atrial (A) filling waves. This method has been validated against a Lagrangian Coherent Structures analysis, is computationally inexpensive and observer independent, making it a potential diagnostic tool in clinical settings.

  13. Cardiac passive-aggressive behavior? The right ventricle in patients with a left ventricular assist device.

    PubMed

    Kimmaliardjuk, Donna May; Ruel, Marc

    2017-04-01

    Right ventricular failure (RVF) affects up to 50% of patients post-left ventricular assist device (LVAD) implantation, and carries significant morbidity and mortality. There is no widely-used long-term mechanical support option for the right ventricle, thus early identification, prevention and medical treatment of RVF is of the upmost importance. Areas covered: A PubMed search was first completed searching 'Right ventricular failure post-LVAD' which yielded 152 results, and a subsequent search was performed under 'RV mechanical support' which yielded 374 results, and was filtered to 'humans' and literature written in English, generating 219 results. We focused this research on pre-operative risk factors identified in the literature for developing RVF-post LVAD implantation, and the medical and surgical treatment options for RVF, including mechanical treatment options. Expert commentary: There is little consensus on pre-operative risk factors that reliably predict RVF post-LVAD implantation. Large prospective randomized trials would help clarify indications for specific medical and surgical therapy. We gather this knowledge in the present article and describe the main RVF remediation modalities. Surgeons and anesthesiologists should help prevent and have a low threshold for initiating supportive treatment for RVF, which may include increasingly invasive therapies up to long-term mechanical RV support.

  14. Markov random field modeling for three-dimensional reconstruction of the left ventricle in cardiac angiography

    PubMed Central

    Medina, Rubén; Garreau, Mireille; Toro, Javier; Le Breton, Hervé; Coatrieux, Jean-Louis; Jugo, Diego

    2006-01-01

    This paper reports on a method for left ventricle three-dimensional reconstruction from two orthogonal ventriculograms. The proposed algorithm is voxel-based and takes into account the conical projection geometry associated with the biplane image acquisition equipment. The reconstruction process starts with an initial ellipsoidal approximation derived from the input ventriculograms. This model is subsequently deformed in such a way as to match the input projections. To this end, the object is modeled as a three-dimensional Markov-Gibbs random field, and an energy function is defined so that it includes one term that models the projections compatibility and another one that includes the space–time regularity constraints. The performance of this reconstruction method is evaluated by considering the reconstruction of mathematically synthesized phantoms and two 3-D binary databases from two orthogonal synthesized projections. The method is also tested using real biplane ventriculograms. In this case, the performance of the reconstruction is expressed in terms of the projection error, which attains values between 9.50% and 11.78 % for two biplane sequences including a total of 55 images. PMID:16895001

  15. Fully automated segmentation of left ventricle using dual dynamic programming in cardiac cine MR images

    NASA Astrophysics Data System (ADS)

    Jiang, Luan; Ling, Shan; Li, Qiang

    2016-03-01

    Cardiovascular diseases are becoming a leading cause of death all over the world. The cardiac function could be evaluated by global and regional parameters of left ventricle (LV) of the heart. The purpose of this study is to develop and evaluate a fully automated scheme for segmentation of LV in short axis cardiac cine MR images. Our fully automated method consists of three major steps, i.e., LV localization, LV segmentation at end-diastolic phase, and LV segmentation propagation to the other phases. First, the maximum intensity projection image along the time phases of the midventricular slice, located at the center of the image, was calculated to locate the region of interest of LV. Based on the mean intensity of the roughly segmented blood pool in the midventricular slice at each phase, end-diastolic (ED) and end-systolic (ES) phases were determined. Second, the endocardial and epicardial boundaries of LV of each slice at ED phase were synchronously delineated by use of a dual dynamic programming technique. The external costs of the endocardial and epicardial boundaries were defined with the gradient values obtained from the original and enhanced images, respectively. Finally, with the advantages of the continuity of the boundaries of LV across adjacent phases, we propagated the LV segmentation from the ED phase to the other phases by use of dual dynamic programming technique. The preliminary results on 9 clinical cardiac cine MR cases show that the proposed method can obtain accurate segmentation of LV based on subjective evaluation.

  16. New Mathematical Model for the Surface Area of the Left Ventricle by the Truncated Prolate Spheroid

    PubMed Central

    Vale, Marcos de Paula; Martinez, Carlos Barreira

    2017-01-01

    The main aim of this study was the formula application of the superficial area of a truncated prolate spheroid (TPS) in Cartesian coordinates in obtaining a cardiac parameter that is not so much discussed in literature, related to the left ventricle (LV) surface area of the human heart, by age and sex. First we obtain a formula for the area of a TPS. Then a simple mathematical model of association of the axes measures of a TPS with the axes of the LV is built. Finally real values of the average dimensions of the humans LV are used to measure surface areas approximations of this heart chamber. As a result, the average superficial area of LV for normal patients is obtained and it is observed that the percentage differences of areas between men and women and their consecutive age groups are constant. A strong linear correlation between the obtained areas and the ventricular volumes normalized by the body areas was observed. The obtained results indicate that the superficial area of the LV, besides enabling a greater knowledge of the geometrical characteristics of the human LV, may be used as one of the normality cardiac verification criteria and be useful for medical and biological applications. PMID:28547001

  17. Single-breath-hold 3-D CINE imaging of the left ventricle using Cartesian sampling.

    PubMed

    Wetzl, Jens; Schmidt, Michaela; Pontana, François; Longère, Benjamin; Lugauer, Felix; Maier, Andreas; Hornegger, Joachim; Forman, Christoph

    2017-05-26

    Our objectives were to evaluate a single-breath-hold approach for Cartesian 3-D CINE imaging of the left ventricle with a nearly isotropic resolution of [Formula: see text] and a breath-hold duration of [Formula: see text]19 s against a standard stack of 2-D CINE slices acquired in multiple breath-holds. Validation is performed with data sets from ten healthy volunteers. A Cartesian sampling pattern based on the spiral phyllotaxis and a compressed sensing reconstruction method are proposed to allow 3-D CINE imaging with high acceleration factors. The fully integrated reconstruction uses multiple graphics processing units to speed up the reconstruction. The 2-D CINE and 3-D CINE are compared based on ventricular function parameters, contrast-to-noise ratio and edge sharpness measurements. Visual comparisons of corresponding short-axis slices of 2-D and 3-D CINE show an excellent match, while 3-D CINE also allows reformatting to other orientations. Ventricular function parameters do not significantly differ from values based on 2-D CINE imaging. Reconstruction times are below 4 min. We demonstrate single-breath-hold 3-D CINE imaging in volunteers and three example patient cases, which features fast reconstruction and allows reformatting to arbitrary orientations.

  18. Manifold parametrization of the left ventricle for a statistical modelling of its complete anatomy

    NASA Astrophysics Data System (ADS)

    Gil, D.; Garcia-Barnes, J.; Hernández-Sabate, A.; Marti, E.

    2010-03-01

    Distortion of Left Ventricle (LV) external anatomy is related to some dysfunctions, such as hypertrophy. The architecture of myocardial fibers determines LV electromechanical activation patterns as well as mechanics. Thus, their joined modelling would allow the design of specific interventions (such as peacemaker implantation and LV remodelling) and therapies (such as resynchronization). On one hand, accurate modelling of external anatomy requires either a dense sampling or a continuous infinite dimensional approach, which requires non-Euclidean statistics. On the other hand, computation of fiber models requires statistics on Riemannian spaces. Most approaches compute separate statistical models for external anatomy and fibers architecture. In this work we propose a general mathematical framework based on differential geometry concepts for computing a statistical model including, both, external and fiber anatomy. Our framework provides a continuous approach to external anatomy supporting standard statistics. We also provide a straightforward formula for the computation of the Riemannian fiber statistics. We have applied our methodology to the computation of complete anatomical atlas of canine hearts from diffusion tensor studies. The orientation of fibers over the average external geometry agrees with the segmental description of orientations reported in the literature.

  19. Flow Behavior in the Left Heart Ventricle Following Apico-Aortic Bypass Surgery

    NASA Astrophysics Data System (ADS)

    Shahriari, Shahrokh; Jeyhani, Morteza; Labrosse, Michel; Kadem, Lyes

    2013-11-01

    Apico-aortic bypass (AAB) surgery is an alternative for transcatheter aortic valve implantation (TAVI) to reduce left ventricle (LV) overload in patients with severe aortic stenosis (AS). It consists in connecting the apex of the LV to the descending thoracic aorta with a valved conduit. Postoperative flow assessments show that two thirds of the outflow is conducted from the LV apex to the conduit, while only one third crosses the native aortic valve. In this study, we performed high speed particle image velocimetry (PIV) measurements of flow pattern within an in vitro elastic model of LV in the presence of a very severe AS, before and after AAB. Results indicate that AAB effectively relieves the LV outflow obstruction; however, it also leads to abnormal ventricular flow patterns. Normal LV flow dynamics is characterized by an emerging mitral jet flow followed by the development of a vortical flow with velocities directed towards the aortic valve, while measurements in the presence of AAB show systolic flow bifurcating to the apical conduit and to the aortic valve outflow tract. This study provides the first insight into the LV flow structure after AAB including outflow jets and disturbed stagnation regions.

  20. Relative pressure imaging in left ventricle using ultrasonic vector flow mapping

    NASA Astrophysics Data System (ADS)

    Tanaka, Tomohiko; Okada, Takashi; Nishiyama, Tomohide; Seki, Yoshinori

    2017-07-01

    Ultrasonic relative pressure imaging (RPI) visualizing pressure distribution on the basis of vector flow mapping (VFM) was developed by applying the momentum equations of fluid motion (Navier-Stokes equations; NSE) for the two-dimensional (2D)-VFM velocity fields. Numerical investigations using three-dimensional (3D) jets with a size similar to the left ventricle (LV) quantified degradations caused by the flow three-dimensionality of convection in the range of 0.1 mmHg. Experimental validation using an LV phantom quantitatively compared two-point intraventricular pressure differences (IVPDs) obtained by RPI, two pressure sensors (grand truth), and color M-mode (CMM) with a high frame rate of 167 Hz in diastole where a transient term is dominant. All measurements of IVPDs in diastole were in good agreement, although the peak value of IVPD by RPI was underestimated by about 35%, mainly because of its insufficient frame rate of 35 Hz. A dependence of the frame rate on IVPD was examined by down-sampled CMM. Although IVPD based on down-sampled CMM at 27 Hz similar to that of the current RPI frame rate showed that the accuracy was underestimated by 30%, a higher data rate of more than 60 Hz, which could be realized in the near future, provided reasonable accuracy with less than 10% error.

  1. Radiofrequency catheter ablation of the atrioventricular junction from the left ventricle

    SciTech Connect

    Sousa, J.; el-Atassi, R.; Rosenheck, S.; Calkins, H.; Langberg, J.; Morady, F. )

    1991-08-01

    The purpose of this study was to describe a new technique for catheter ablation of the atrioventricular junction using radiofrequency energy delivered in the left ventricle. Catheter ablation of the atrioventricular (AV) junction using a catheter positioned across the tricuspid annulus was unsuccessful in eight patients with a mean {plus minus} SD age of 51 {plus minus} 19 years who had AV nodal reentry tachycardia (three patients), orthodromic tachycardia using a concealed midseptal accessory pathway, atrial tachycardia, atrial flutter (two patients), or atrial fibrillation. Before attempts at catheter ablation of the AV junction, each patient had been refractory to pharmacological therapy, and four had failed attempts at either catheter modification of the AV node using radiofrequency energy or surgical and catheter ablation of the accessory pathway. Conventional right-sided catheter ablation of the AV junction using radiofrequency energy in six patients and both radiofrequency energy and direct current shocks in two patients was ineffective. The mean amplitude of the His bundle potential recorded at the tricuspid annulus at the sites of unsuccessful AV junction ablation was 0.1 {plus minus} 0.08 mV, with a maximum His amplitude of 0.03-0.28 mV. A 7F deflectable-tip quadripolar electrode catheter with a 4-mm distal electrode was positioned against the upper left ventricular septum using a retrograde aortic approach from the femoral artery. Third-degree AV block was induced in each of the eight patients with 20-36 W applied for 15-30 seconds. The His bundle potential at the sites of successful AV junction ablation ranged from 0.06 to 0.99 mV, with a mean of 0.27 {plus minus} 0.32 mV. There was no rise in the creatine kinase-MB fraction and no complications occurred. An intrinsic escape rhythm of 30-60 beats/min was present in seven of the eight patients.

  2. The Effects of Right Ventricular Apical Pacing Frequency on Left Ventricle Function and Pulmonary Artery Pressure.

    PubMed

    Fanari, Zaher; Hammami, Sumaya; Hammami, Muhammad Baraa; Hammami, Safa; Shuraih, Mossaab

    2015-08-01

    We studied the effect of the frequency of right ventricular (HV) pacing on left ventricle (LV) function pulmonary hypertension. The incidence of new or worsening pulmonary hypertension after permanent pacemaker (PPM) or implantable cardioverter defibrillator (lCD) lead placement has not been well investigated. We reviewed the charts of all patients undergoing PPM or ICD lead placement in our electrophysiology laboratory from December 2007 to December 2012. Two hundred and six patients (120 with PPM and 86 with ICD) had baseline echocardiography within six months before, and a follow up study at least six months after lead insertion. The mean age was 74 ± 14 years; 56 percent were men. The follow-up period was 29 ± 19 months. RV pacing was associated with a worsening of left ventricular ejection fraction (LVEF) in patients with high frequency of RV (55 ± 16 vs. 44 ± 18; P = 0.001), but not with those with low frequency pacing (55 ± 16 vs. 54 ± 17; P = 0.87). Similarly, RV pacing was associated with a worsening in both right ventricular systolic pressure (RVSP) (42 ± 14 vs. 48 ± 15; P = 0.01) and Pulmonary Artery Systolic Pressure (PASP) (50 ± 17 vs. 56 ± 18; P = 0.005) in patients with high frequency RV, but not in those with low frequency RV pacing [RVSP (43 ± 12 vs. 46 ± 13; P = 0.06) and PASP (51 ± 15 vs. 54 ± 16; P = 0.11)]. PPM or IICD lead implantation worsens LV function and pulmonary hypertension in patients with high frequency of RV pacing frequency. This is probably caused by the mechanical dyssynchrony induced by RV pacing.

  3. A CLINICAL METHOD FOR MAPPING AND QUANTIFYING BLOOD STASIS IN THE LEFT VENTRICLE

    PubMed Central

    Rossini, Lorenzo; Martinez-Legazpi, Pablo; Vu, Vi; Fernández-Friera, Leticia; del Villar, Candelas Pèrez; Rodríguez-López, Sara; Benito, Yolanda; Borja, María-Guadalupe; Pastor-Escuredo, David; Yotti, Raquel; Ledesma-Carbayo, María J.; Kahn, Andrew M.; Ibáñez, Borja; Fernández-Avilès, Francisco; May-Newman, Karen; Bermejo, Javier; del Álamo, Juan C.

    2015-01-01

    In patients at risk of intraventricular thrombosis, the benefits of chronic anticoagulation therapy need to be balanced with the pro-hemorrhagic effects of therapy. Blood stasis in the cardiac chambers is a recognized risk factor for intracardiac thrombosis and potential cardiogenic embolic events. In this work, we present a novel flow image-based method to assess the location and extent of intraventricular stasis regions inside the left ventricle (LV) by digital processing flow-velocity images obtained either by phase-contrast magnetic resonance (PCMR) or 2D color-Doppler velocimetry (echo-CDV). This approach is based on quantifying the distribution of the blood Residence Time (TR) from time-resolved blood velocity fields in the LV. We tested the new method in illustrative examples of normal hearts, patients with dilated cardiomyopathy and one patient before and after the implantation of a left ventricular assist device (LVAD). The method allowed us to assess in-vivo the location and extent of the stasis regions in the LV. Original metrics were developed to integrate flow properties into simple scalars suitable for a robust and personalized assessment of the risk of thrombosis. From a clinical perspective, this work introduces the new paradigm that quantitative flow dynamics can provide the basis to obtain subclinical markers of intraventricular thrombosis risk. The early prediction of LV blood stasis may result in decrease strokes by appropriate use of anticoagulant therapy for the purpose of primary and secondary prevention. It may also have a significant impact on LVAD device design and operation set-up. PMID:26680013

  4. Echocardiographic detection of free-floating thrombus in left ventricle during coronary artery bypass grafting

    PubMed Central

    Vaggar, Jagadeesh N.; Gadhinglajkar, Shrinivas; Pillai, Vivek; Sreedhar, Rupa; Cahndran, Roshith; Roy, Suddhadeb

    2015-01-01

    We report an incident of detection of a free-floating thrombus in the left ventricle (LV) using intraoperative two-dimensional (2D) and three-dimensional (3D) transesophageal echocardiography (TEE) during proximal coronary artery bypass graft anastomosis. A 58-year-old man presented to us with a 6-month history of chest pain without any history suggestive of myocardial infarction or transient ischemic attacks. His preoperative echocardiography revealed the systolic dysfunction of LV, mild hypokinesia of basal and mid-anterior wall, and the absence of an aneurysm. He was scheduled for on-pump coronary artery bypass surgery. On intraoperative TEE before establishing cardiopulmonary bypass (CPB), a small immobile mass was found attached to LV apical area. After completion of distal coronary artery grafting, when the aortic cross-clamp was removed, the heart was filled partially and beating spontaneously. TEE examination using 2D mode revealed a free-floating mass in the LV, which was suspected to be a thrombus. Additional navigation using biplane and 3D modes confirmed the presence of the thrombus and distinguished it from papillary muscles and artifact. The surgeon opened the left atrium after re-establishing electromechanical quiescence and removed a thrombus measuring 1.5 cm × 1 cm from the LV. The LV mass in the apical region was no longer seen after discontinuation of CPB. Accurate TEE-detection and timely removal of the thrombus averted disastrous embolic complications. Intraoperative 2D and recent biplane and 3D echocardiography modes are useful monitoring tools during the conduct of CPB. PMID:26440248

  5. [Effectiveness of anticoagulant oral treatment in patients with thrombus in left ventricle after acute myocardial infarction].

    PubMed

    Carrillo, A M; Valdespino, A; Solorio, S; Badui, E; Enciso, R; Lepe, L; Lara, A; Ocampo, S; Alonso, R; Romero, M A

    1997-01-01

    Left ventricular mural thrombi (LVMT) is a complication of acute myocardial infarction (AMI), that may produce peripheral embolism which could be fatal. In order to establish an adequate time of oral anticoagulant (OA) therapy, we undertook a prospective study that included 45 patients with AMI and left ventricular thrombi detected by echocardiographic study, in the first 5 to 10 days postinfarction, the study was repeated, in 3 and 6 months. Treatment with oral anticoagulant was initiated at the point of the detection of thrombi maintaining an INR of 1.5 to 2. Thirty nine patients (79%) were males and 6 (11%) were females, with an age of 29 to 85 years and a range of 62 +/- 11 years. Forty four patients (98%) presented anterior wall infarction and 1 (2%) posteroinferior infarction. In patients with anterior infarction, in 38 (85%) the thrombi was located at the apical wall (p < 0.05), 5 (11%) in the septal wall and other (2%) in anterior and apical walls. The patient with the posteroinferior infarction presented extension to the right ventricle, where the thrombus was located (2%). The contractility alterations related with thrombi were diskinesia, followed by hipokinesia and finally akinesia. The ejection fraction had not relationship with thrombi formation. LVMT dissolved in 32 patients (71%) at 3 months (p < 0.05), in 8 (18%) in 6 months and in 5 (11%) it was maintained for more than 6 months. None of the patients presented complications of OA. We conclude that the LVMT are more frequent in anterior infarctions, essentially in those that present diskinesia. The majority of LVMT are resolved in 6 months with OA therapy.

  6. Books and monographs on finite element technology

    NASA Technical Reports Server (NTRS)

    Noor, A. K.

    1985-01-01

    The present paper proviees a listing of all of the English books and some of the foreign books on finite element technology, taking into account also a list of the conference proceedings devoted solely to finite elements. The references are divided into categories. Attention is given to fundamentals, mathematical foundations, structural and solid mechanics applications, fluid mechanics applications, other applied science and engineering applications, computer implementation and software systems, computational and modeling aspects, special topics, boundary element methods, proceedings of symmposia and conferences on finite element technology, bibliographies, handbooks, and historical accounts.

  7. Books and monographs on finite element technology

    NASA Technical Reports Server (NTRS)

    Noor, A. K.

    1985-01-01

    The present paper proviees a listing of all of the English books and some of the foreign books on finite element technology, taking into account also a list of the conference proceedings devoted solely to finite elements. The references are divided into categories. Attention is given to fundamentals, mathematical foundations, structural and solid mechanics applications, fluid mechanics applications, other applied science and engineering applications, computer implementation and software systems, computational and modeling aspects, special topics, boundary element methods, proceedings of symmposia and conferences on finite element technology, bibliographies, handbooks, and historical accounts.

  8. Right coronary artery fistula to left ventricle treated by transcatheter coil embolization: a case report and literature review.

    PubMed

    Jiang, Zhenni; Chen, Han; Wang, Jian'an

    2012-01-01

    A coronary artery fistula between a coronary artery and a cardiac chamber is a rare condition. We reported a case of right coronary artery fistula to the left ventricle in a 57-year-old man who had 2-year history of chest pain and exercise dyspnea without significant coronary atherosclerosis with abnormal left ventricular size and function. It was important to recognize this anomaly and our experience showed that transcatheter occlusion of coronary artery fistula was a safe and effective procedure in the presence of symptoms of congestive heart failure, significant left-to-right shunt or refractory to medical treatment.

  9. A survey of mixed finite element methods

    NASA Technical Reports Server (NTRS)

    Brezzi, F.

    1987-01-01

    This paper is an introduction to and an overview of mixed finite element methods. It discusses the mixed formulation of certain basic problems in elasticity and hydrodynamics. It also discusses special techniques for solving the discrete problem.

  10. Finite element schemes for Fermi equation

    NASA Astrophysics Data System (ADS)

    Asadzadeh, M.; Beilina, L.; Naseer, M.; Standar, C.

    2017-07-01

    A priori error estimates are derived for the streamline diffusion (SD) finite element methods for the Fermi pencil-beam equation. Two-dimensional numerical examples confirm our theoretical investigations.

  11. Attenuated sarcomere lengthening of the aged murine left ventricle observed using two-photon fluorescence microscopy.

    PubMed

    Nance, Michael E; Whitfield, Justin T; Zhu, Yi; Gibson, Anne K; Hanft, Laurin M; Campbell, Kenneth S; Meininger, Gerald A; McDonald, Kerry S; Segal, Steven S; Domeier, Timothy L

    2015-09-01

    The Frank-Starling mechanism, whereby increased diastolic filling leads to increased cardiac output, depends on increasing the sarcomere length (Ls) of cardiomyocytes. Ventricular stiffness increases with advancing age, yet it remains unclear how such changes in compliance impact sarcomere dynamics in the intact heart. We developed an isolated murine heart preparation to monitor Ls as a function of left ventricular pressure and tested the hypothesis that sarcomere lengthening in response to ventricular filling is impaired with advanced age. Mouse hearts isolated from young (3-6 mo) and aged (24-28 mo) C57BL/6 mice were perfused via the aorta under Ca(2+)-free conditions with the left ventricle cannulated to control filling pressure. Two-photon imaging of 4-{2-[6-(dioctylamino)-2-naphthalenyl]ethenyl}1-(3-sulfopropyl)-pyridinium fluorescence was used to monitor t-tubule striations and obtain passive Ls between pressures of 0 and 40 mmHg. Ls values (in μm, aged vs. young, respectively) were 2.02 ± 0.04 versus 2.01 ± 0.02 at 0 mmHg, 2.13 ± 0.04 versus 2.23 ± 0.02 at 5 mmHg, 2.21 ± 0.03 versus 2.27 ± 0.03 at 10 mmHg, and 2.28 ± 0.02 versus 2.36 ± 0.01 at 40 mmHg, indicative of impaired sarcomere lengthening in aged hearts. Atomic force microscopy nanoindentation revealed that intact cardiomyocytes enzymatically isolated from aged hearts had increased stiffness compared with those of young hearts (elastic modulus: aged, 41.9 ± 5.8 kPa vs. young, 18.6 ± 3.3 kPa; P = 0.006). Impaired sarcomere lengthening during left ventricular filling may contribute to cardiac dysfunction with advancing age by attenuating the Frank-Starling mechanism and reducing stroke volume.

  12. Finite element modeling of the human pelvis

    SciTech Connect

    Carlson, B.

    1995-11-01

    A finite element model of the human pelvis was created using a commercial wire frame image as a template. To test the final mesh, the model`s mechanical behavior was analyzed through finite element analysis and the results were displayed graphically as stress concentrations. In the future, this grid of the pelvis will be integrated with a full leg model and used in side-impact car collision simulations.

  13. Optimizing header strength utilizing finite element analyses

    NASA Astrophysics Data System (ADS)

    Burchett, S. N.

    Finite element techniques have been successfully applied as a design tool in the optimization of high strength headers for pyrotechnic-driven actuators. These techniques have been applied to three aspects of the design process of a high strength header. The design process was a joint effort of experts from several disciplines including design engineers, material scientists, test engineers, manufacturing engineers, and structural analysts. Following material selection, finite element techniques were applied to evaluate the residual stresses due to manufacturing which were developed in the high strength glass ceramic-to-metal seal headers. Results from these finite element analyses were used to identify header designs which were manufacturable and had a minimum residual stress state. Finite element techniques were than applied to obtain the response of the header due to pyrotechnic burn. The results provided realistic upper bounds on the pressure containment ability of various preliminary header designs and provided a quick and inexpensive method of strengthening and refining the designs. Since testing of the headers was difficult and sometimes destructive, results of the analyses were also used to interpret test results and identify failure modes. In this paper, details of the finite element element techniques including the models used, material properties, material failure models, and loading will be presented. Results from the analyses showing the header failure process will also be presented. This paper will show that significant gains in capability and understanding can result when finite element techniques are included as an integral part of the design process of complicated high strength headers.

  14. Finite element analysis of posterior cervical fixation.

    PubMed

    Duan, Y; Wang, H H; Jin, A M; Zhang, L; Min, S X; Liu, C L; Qiu, S J; Shu, X Q

    2015-02-01

    Despite largely, used in the past, biomechanical test, to investigate the fixation techniques of subaxial cervical spine, information is lacking about the internal structural response to external loading. It is not yet clear which technique represents the best choice and whether stabilization devices can be efficient and beneficial for three-column injuries (TCI). The different posterior cervical fixation techniques (pedicle screw PS, lateral mass screw LS, and transarticular screw TS) have respective indications. A detailed, geometrically accurate, nonlinear C3-C7 finite element model (FEM) had been successfully developed and validated. Then three FEMs were reconstructed from different fixation techniques after C4-C6 TCI. A compressive preload of 74N combined with a pure moment of 1.8 Nm in flexion, extension, left-right lateral bending, and left-right axial rotation was applied to the FEMs. The ROM results showed that there were obvious significant differences when comparing the different fixation techniques. PS and TS techniques can provide better immediate stabilization, compared to LS technique. The stress results showed that the variability of von Mises stress in the TS fixation device was minimum and LS fixation device was maximum. Furthermore, the screws inserted by TS technique had high stress concentration at the middle part of the screws. Screw inserted by PS and LS techniques had higher stress concentration at the actual cap-rod-screw interface. The research considers that spinal surgeon should first consider using the TS technique to treat cervical TCI. If PS technique is used, we should eventually prolong the need for external bracing in order to reduce the higher risk of fracture on fixation devices. If LS technique is used, we should add anterior cervical operation for acquire a better immediate stabilization. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  15. On the three-dimensional vortical structure of early diastolic flow in a patient-specific left ventricle

    PubMed Central

    Le, Trung Bao; Sotiropoulos, Fotis

    2012-01-01

    We study the formation of the mitral vortex ring during early diastolic filling in a patient-specific left ventricle using direct numerical simulation. The geometry of the left ventricle is reconstructed from Magnetic Resonance Imaging (MRI). The heart wall motion is modeled by a cell-based activation methodology, which yields physiologic kinematics with heart rate equal to 52 beats per minute. We show that the structure of the mitral vortex ring consists of the main vortex ring and trailing vortex tubes, which originate at the heart wall. The trailing vortex tubes play an important role in exciting twisting circumferential instability modes of the mitral vortex ring. At the end of diastole, the vortex ring impinges on the wall and the intraventricular flow transitions to a weak turbulent state. Our results can be used to help interprete and analyze three-dimensional in–vivo flow measurements obtained with MRI. PMID:22773898

  16. On the three-dimensional vortical structure of early diastolic flow in a patient-specific left ventricle.

    PubMed

    Le, Trung Bao; Sotiropoulos, Fotis

    2012-09-01

    We study the formation of the mitral vortex ring during early diastolic filling in a patient-specific left ventricle using direct numerical simulation. The geometry of the left ventricle is reconstructed from Magnetic Resonance Imaging (MRI). The heart wall motion is modeled by a cell-based activation methodology, which yields physiologic kinematics with heart rate equal to 52 beats per minute. We show that the structure of the mitral vortex ring consists of the main vortex ring and trailing vortex tubes, which originate at the heart wall. The trailing vortex tubes play an important role in exciting twisting circumferential instability modes of the mitral vortex ring. At the end of diastole, the vortex ring impinges on the wall and the intraventricular flow transitions to a weak turbulent state. Our results can be used to help interprete and analyze three-dimensional in-vivo flow measurements obtained with MRI.

  17. Injuries to the Aorta, Aortic Annulus, and Left Ventricle During Transcatheter Aortic Valve Replacement: Management and Outcomes.

    PubMed

    Langer, Nathaniel B; Hamid, Nadira B; Nazif, Tamim M; Khalique, Omar K; Vahl, Torsten P; White, Jonathon; Terre, Juan; Hastings, Ramin; Leung, Diana; Hahn, Rebecca T; Leon, Martin; Kodali, Susheel; George, Isaac

    2017-01-01

    The experience with transcatheter aortic valve replacement is increasing worldwide; however, the incidence of potentially catastrophic cardiac or aortic complications has not decreased. In most cases, significant injuries to the aorta, aortic valve annulus, and left ventricle require open surgical repair. However, the transcatheter aortic valve replacement patient presents a unique challenge as many patients are at high or prohibitive surgical risk and, therefore, an open surgical procedure may not be feasible or appropriate. Consequently, prevention of these potentially catastrophic injuries is vital, and practitioners need to understand when open surgical repair is required and when alternative management strategies can be used. The goal of this article is to provide an overview of current management and prevention strategies for major complications involving the aorta, aortic valve annulus, and left ventricle.

  18. Numerical simulation of the blood-wall interaction in the human left ventricle

    NASA Astrophysics Data System (ADS)

    Chahboune, B.; Crolet, J. M.

    1998-06-01

    This paper presents a contribution to the numerical simulation of the left ventricle taking into account simultaneously the fluid flow inside the cavity and the motion of the cardiac wall. One describes mathematical tools which are useful for such a problem of fluid-structure interaction. After having written the continuous mathematical problem and noted the difficulties which exist to solve such a problem, one makes two important simplifying assumptions: on the one hand, one builds a new problem which, on the mathematical viewpoint, can be distinguished from the continuous problem but which, on the physical and physiological viewpoints, can be considered as acceptable. One builds then a software which has to be considered just as a numerical investigation tool. It can be noted that it is necessary to impose, for the shape of the cardiac wall, a time-evolution. Such a bi-dimensional framework is sufficient to study the numerical aspect of this interaction, but is not sufficient to investigate the effects of major parameters governing the behavior of the left ventricle. Cet article est une contribution à la simulation numérique du comportement du ventricule gauche prenant simultanément en compte l'écoulement du fluide dans la cavité et le mouvement de la paroi cardiaque. Les outils mathématiques nécessaires à une telle étude d'interaction fluide-structure sont présentés. Après avoir écrit le problème mathématique continu et noté les difficultés liées à la résolution d'un tel problème, deux hypothèses simplificatrices sont émises. D'une part, on construit un nouveau problème qui, sur le plan mathématique, est différent du problème continu mais qui, sur le plan physique et physiologique peut être considéré comme acceptable par rapport au problème initial. Puis on construit un logiciel qui doit être considéré comme un outil d'investigation numérique. On constate alors qu'il est nécessaire de faire évoluer dans le temps la g

  19. Integration of electro-anatomical and imaging data of the left ventricle: An evaluation framework.

    PubMed

    Soto-Iglesias, David; Butakoff, Constantine; Andreu, David; Fernández-Armenta, Juan; Berruezo, Antonio; Camara, Oscar

    2016-08-01

    Integration of electrical and structural information for scar characterization in the left ventricle (LV) is a crucial step to better guide radio-frequency ablation therapies, which are usually performed in complex ventricular tachycardia (VT) cases. This integration requires finding a common representation where to map the electrical information from the electro-anatomical map (EAM) surfaces and tissue viability information from delay-enhancement magnetic resonance images (DE-MRI). However, the development of a consistent integration method is still an open problem due to the lack of a proper evaluation framework to assess its accuracy. In this paper we present both: (i) an evaluation framework to assess the accuracy of EAM and imaging integration strategies with simulated EAM data and a set of global and local measures; and (ii) a new integration methodology based on a planar disk representation where the LV surface meshes are quasi-conformally mapped (QCM) by flattening, allowing for simultaneous visualization and joint analysis of the multi-modal data. The developed evaluation framework was applied to estimate the accuracy of the QCM-based integration strategy on a benchmark dataset of 128 synthetically generated ground-truth cases presenting different scar configurations and EAM characteristics. The obtained results demonstrate a significant reduction in global overlap errors (50-100%) with respect to state-of-the-art integration techniques, also better preserving the local topology of small structures such as conduction channels in scars. Data from seventeen VT patients were also used to study the feasibility of the QCM technique in a clinical setting, consistently outperforming the alternative integration techniques in the presence of sparse and noisy clinical data. The proposed evaluation framework has allowed a rigorous comparison of different EAM and imaging data integration strategies, providing useful information to better guide clinical practice in

  20. A Patient-Specific Computational Fluid Dynamic Model for Hemodynamic Analysis of Left Ventricle Diastolic Dysfunctions.

    PubMed

    Nguyen, Vinh-Tan; Wibowo, Stella Nathania; Leow, Yue An; Nguyen, Hoang-Huy; Liang, Zhong; Leo, Hwa Liang

    2015-12-01

    This work presents a computational fluid dynamic (CFD) model to simulate blood flows through the human heart's left ventricles (LV), providing patient-specific time-dependent hemodynamic characteristics from reconstructed MRI scans of LV. These types of blood flow visualization can be of great asset to the medical field helping medical practitioners better predict the existence of any abnormalities in the patient, hence offer an appropriate treatment. The methodology employed in this work processed geometries obtained from MRI scans of patient-specific LV throughout a cardiac cycle using computer-aided design tool. It then used unstructured mesh generation techniques to generate surface and volume meshes for flow simulations; thus provided flow visualization and characteristics in patient-specific LV. The resulting CFD model provides three dimensional velocity streamlines on the geometries at specific times in a cardiac cycle, and they are compared with existing literature findings, such as data from echocardiography particle image velocimetry. As an important flow characteristic, vortex formation of the blood flow of healthy as well as diseased subjects having a LV dysfunction condition are also obtained from simulations and further investigated for potential diagnosis. The current work established a pipeline for a non-invasive diagnostic tool for diastolic dysfunction by generating patient-specific LV models and CFD models in the spatiotemporal dimensions. The proposed framework was applied for analysis of a group of normal subjects and patients with cardiac diseases. Results obtained using the numerical tool showed distinct differences in flow characteristics in the LV between patient with diastolic dysfunction and healthy subjects. In particular, vortex structures do not develop during cardiac cycles for patients while it was clearly seen in the normal subjects. The current LV CFD model has proven to be a promising technology to aid in the diagnosis of LV

  1. Left ventricle segmentation in cardiac MRI images using fully convolutional neural networks

    NASA Astrophysics Data System (ADS)

    Vázquez Romaguera, Liset; Costa, Marly Guimarães Fernandes; Romero, Francisco Perdigón; Costa Filho, Cicero Ferreira Fernandes

    2017-03-01

    According to the World Health Organization, cardiovascular diseases are the leading cause of death worldwide, accounting for 17.3 million deaths per year, a number that is expected to grow to more than 23.6 million by 2030. Most cardiac pathologies involve the left ventricle; therefore, estimation of several functional parameters from a previous segmentation of this structure can be helpful in diagnosis. Manual delineation is a time consuming and tedious task that is also prone to high intra and inter-observer variability. Thus, there exists a need for automated cardiac segmentation method to help facilitate the diagnosis of cardiovascular diseases. In this work we propose a deep fully convolutional neural network architecture to address this issue and assess its performance. The model was trained end to end in a supervised learning stage from whole cardiac MRI images input and ground truth to make a per pixel classification. For its design, development and experimentation was used Caffe deep learning framework over an NVidia Quadro K4200 Graphics Processing Unit. The net architecture is: Conv64-ReLU (2x) - MaxPooling - Conv128-ReLU (2x) - MaxPooling - Conv256-ReLU (2x) - MaxPooling - Conv512-ReLu-Dropout (2x) - Conv2-ReLU - Deconv - Crop - Softmax. Training and testing processes were carried out using 5-fold cross validation with short axis cardiac magnetic resonance images from Sunnybrook Database. We obtained a Dice score of 0.92 and 0.90, Hausdorff distance of 4.48 and 5.43, Jaccard index of 0.97 and 0.97, sensitivity of 0.92 and 0.90 and specificity of 0.99 and 0.99, overall mean values with SGD and RMSProp, respectively.

  2. Aberrant Glycosylation in the Left Ventricle and Plasma of Rats with Cardiac Hypertrophy and Heart Failure.

    PubMed

    Nagai-Okatani, Chiaki; Minamino, Naoto

    2016-01-01

    Targeted proteomics focusing on post-translational modifications, including glycosylation, is a useful strategy for discovering novel biomarkers. To apply this strategy effectively to cardiac hypertrophy and resultant heart failure, we aimed to characterize glycosylation profiles in the left ventricle and plasma of rats with cardiac hypertrophy. Dahl salt-sensitive hypertensive rats, a model of hypertension-induced cardiac hypertrophy, were fed a high-salt (8% NaCl) diet starting at 6 weeks. As a result, they exhibited cardiac hypertrophy at 12 weeks and partially impaired cardiac function at 16 weeks compared with control rats fed a low-salt (0.3% NaCl) diet. Gene expression analysis revealed significant changes in the expression of genes encoding glycosyltransferases and glycosidases. Glycoproteome profiling using lectin microarrays indicated upregulation of mucin-type O-glycosylation, especially disialyl-T, and downregulation of core fucosylation on N-glycans, detected by specific interactions with Amaranthus caudatus and Aspergillus oryzae lectins, respectively. Upregulation of plasma α-l-fucosidase activity was identified as a biomarker candidate for cardiac hypertrophy, which is expected to support the existing marker, atrial natriuretic peptide and its related peptides. Proteomic analysis identified cysteine and glycine-rich protein 3, a master regulator of cardiac muscle function, as an O-glycosylated protein with altered glycosylation in the rats with cardiac hypertrophy, suggesting that alternations in O-glycosylation affect its oligomerization and function. In conclusion, our data provide evidence of significant changes in glycosylation pattern, specifically mucin-type O-glycosylation and core defucosylation, in the pathogenesis of cardiac hypertrophy and heart failure, suggesting that they are potential biomarkers for these diseases.

  3. Treatment of right ventricle to pulmonary artery conduit stenosis in infants with hypoplastic left heart syndrome.

    PubMed

    Münsterer, Andrea; Kasnar-Samprec, Jelena; Hörer, Jürgen; Cleuziou, Julie; Eicken, Andreas; Malcic, Ivan; Lange, Rüdiger; Schreiber, Christian

    2013-09-01

    To determine the incidence of right ventricle-to-pulmonary artery (RV-PA) conduit stenosis after the Norwood I operation in patients with hypoplastic left heart syndrome (HLHS), and to determine whether the treatment strategy of RV-PA conduit stenosis has an influence on interstage and overall survival. Ninety-six patients had a Norwood operation with RV-PA conduit between 2002 and 2011. Details of reoperations/interventions due to conduit obstruction prior to bidirectional superior cavopulmonary anastomosis (BSCPA) were collected. Overall pre-BSCPA mortality was 17%, early mortality after Norwood, 6%. Early angiography was performed in 34 patients due to desaturation at a median of 8 days after the Norwood operation. Fifteen patients (16%) were diagnosed with RV-PA conduit stenosis that required treatment. The location of the conduit stenosis was significantly different in the patients with non-ringed (proximal) and the patients with ring-enforced conduit (distal), P = 0.004. In 6 patients, a surgical revision of the conduit was performed; 3 of them died prior to BSCPA. Another 6 patients had a stent implantation and 3 were treated with balloon dilatation followed by a BSCPA in the subsequent 2 weeks. All patients who were treated interventionally for RV-PA conduit obstruction had a successful BSCPA. Patients who received a surgical RV-PA conduit revision had a significantly higher interstage (P = 0.044) and overall mortality (P = 0.011) than those who received a stent or balloon dilatation of the stenosis followed by an early BSCPA. RV-PA conduit obstruction after Norwood I procedure in patients with HLHS can be safely and effectively treated by stent implantation, balloon dilatation and early BSCPA. Surgical revision of the RV-PA conduit can be reserved for patients in whom an interventional approach fails, and an early BSCPA is not an option.

  4. Automatic segmentation of left ventricle cavity from short-axis cardiac magnetic resonance images.

    PubMed

    Yang, Xulei; Song, Qing; Su, Yi

    2017-02-03

    In this paper, a computational framework is proposed to perform a fully automatic segmentation of the left ventricle (LV) cavity from short-axis cardiac magnetic resonance (CMR) images. In the initial phase, the region of interest (ROI) is automatically identified on the first image frame of the CMR slices. This is done by partitioning the image into different regions using a standard fuzzy c-means (FCM) clustering algorithm where the LV region is identified according to its intensity, size and circularity in the image. Next, LV segmentation is performed within the identified ROI by using a novel clustering method that utilizes an objective functional with a dissimilarity measure that incorporates a circular shape function. This circular shape-constrained FCM algorithm is able to differentiate pixels with similar intensity but are located in different regions (e.g. LV cavity and non-LV cavity), thus improving the accuracy of the segmentation even in the presence of papillary muscles. In the final step, the segmented LV cavity is propagated to the adjacent image frame to act as the ROI. The segmentation and ROI propagation are then iteratively executed until the segmentation has been performed for the whole cardiac sequence. Experiment results using the LV Segmentation Challenge validation datasets show that our proposed framework can achieve an average perpendicular distance (APD) shift of 2.23 ± 0.50 mm and the Dice metric (DM) index of 0.89 ± 0.03, which is comparable to the existing cutting edge methods. The added advantage over state of the art is that our approach is fully automatic, does not need manual initialization and does not require a prior trained model.

  5. Moderate exercise training does not worsen left ventricle remodeling and function in untreated severe hypertensive rats.

    PubMed

    Boissiere, Julien; Eder, Véronique; Machet, Marie-Christine; Courteix, Daniel; Bonnet, Pierre

    2008-02-01

    Exercise training and hypertension induced cardiac hypertrophy but modulate differently left ventricle (LV) function. This study set out to evaluate cardiac adaptations induced by moderate exercise training in normotensive and untreated severe hypertensive rats. Four groups of animals were studied: normotensive (Ctl) and severe hypertensive (HT) Wistar rats were assigned to be sedentary (Sed) or perform a moderate exercise training (Ex) over a 10-wk period. Severe hypertension was induced in rat by a two-kidney, one-clip model. At the end of the training period, hemodynamic parameters and LV morphology and function were assessed using catheterism and conventional pulsed Doppler echocardiography. LV histology was performed to study fibrosis infiltrations. Severe hypertension increased systolic blood pressure to 202 +/- 9 mmHg and induced pathological hypertrophy (LV hypertrophy index was 0.34 +/- 0.02 vs. 0.44 +/- 0.02 in Ctl-Sed and HT-Sed groups, respectively) with LV relaxation alteration (early-to-atrial wave ratio = 2.02 +/- 0.11 vs. 1.63 +/- 0.12). Blood pressure was not altered by exercise training, but arterial stiffness was reduced in trained hypertensive rats (pulse pressure was 75 +/- 7 vs. 62 +/- 3 mmHg in HT-Sed and HT-Ex groups, respectively). Exercise training induced eccentric hypertrophy in both Ex groups by increasing LV cavity without alteration of LV systolic function. However, LV hypertrophy index was significantly decreased in normotensive rats only (0.34 +/- 0.02 vs. 0.30 +/- 0.02 in Ctl-Sed and Ctl-Ex groups, respectively). Moreover, exercise training improved LV passive filling in Ctl-Ex rats but not in Ht-Ex rats. In this study, exercise training did not reduce blood pressure and induced an additional physiological hypertrophy in untreated HT rats, which was slightly blunted when compared with Ctl rats. However, cardiac function was not worsened by exercise training.

  6. The numerical analysis of non-Newtonian blood flow in human patient-specific left ventricle.

    PubMed

    Doost, Siamak N; Zhong, Liang; Su, Boyang; Morsi, Yosry S

    2016-04-01

    Recently, various non-invasive tools such as the magnetic resonance image (MRI), ultrasound imaging (USI), computed tomography (CT), and the computational fluid dynamics (CFD) have been widely utilized to enhance our current understanding of the physiological parameters that affect the initiation and the progression of the cardiovascular diseases (CVDs) associated with heart failure (HF). In particular, the hemodynamics of left ventricle (LV) has attracted the attention of the researchers due to its significant role in the heart functionality. In this study, CFD owing its capability of predicting detailed flow field was adopted to model the blood flow in images-based patient-specific LV over cardiac cycle. In most published studies, the blood is modeled as Newtonian that is not entirely accurate as the blood viscosity varies with the shear rate in non-linear manner. In this paper, we studied the effect of Newtonian assumption on the degree of accuracy of intraventricular hemodynamics. In doing so, various non-Newtonian models and Newtonian model are used in the analysis of the intraventricular flow and the viscosity of the blood. Initially, we used the cardiac MRI images to reconstruct the time-resolved geometry of the patient-specific LV. After the unstructured mesh generation, the simulations were conducted in the CFD commercial solver FLUENT to analyze the intraventricular hemodynamic parameters. The findings indicate that the Newtonian assumption cannot adequately simulate the flow dynamic within the LV over the cardiac cycle, which can be attributed to the pulsatile and recirculation nature of the flow and the low blood shear rate.

  7. Characterization of left ventricle energy loss in healthy adults using vector flow mapping: Preliminary results.

    PubMed

    Xu, Lei; Sun, Chao; Zhu, Xiaoli; Liu, Weihua; Ta, Shengjun; Zhao, Dan; Wang, Feifei; Liu, Liwen

    2017-05-01

    Energy loss (EL) is a new quantitative hemodynamic index based on vector flow mapping (VFM). This study aimed to characterize EL of the left ventricle (LV) in healthy adults. Fifty-one healthy adults were enrolled in this study. EL of LV was analyzed frame by frame using color Doppler images of a standard apical three-chamber dynamic view on an offline VFM workstation. The average EL of systole and diastole was calculated, and the results were averaged over three cardiac cycles. The average EL for systole and diastole was 11.07±5.82J/m/s and 11.58±5.54 J/m/s, respectively. Multivariate regression analysis showed that the aortic velocity time integral (AOVTI), A-wave peak velocity, and isovolumetric contraction time (IVCT) were independently associated with the average systolic EL. E-wave peak velocity, height, and IVCT were independently associated with the average diastolic EL. For females, the average systolic and diastolic EL was 12.66±7.06J/m/s and 13.90±5.37J/m/s, respectively. For males, the systolic and diastolic EL was 9.29±3.33J/m/s and 8.97±4.55J/m/s, respectively. Energy loss in LV changes regularly during the cardiac cycle. The average systolic EL has a high positive correlation with AOVTI, whereas the average diastolic EL has with E-wave peak velocity. Women have higher average EL than men in both systole and diastole. By recognizing the EL characterization of healthy adults, the variation in EL may reflect cardiac dysfunction. These were preliminary results, and thus, the clinical implications of EL warrant further investigation. © 2017, Wiley Periodicals, Inc.

  8. The application of decision trees algorithm for selecting the area of the left ventricle on echocardiographic images

    NASA Astrophysics Data System (ADS)

    Zyuzin, V. V.; Bobkova, A. O.; Porshnev, S. V.; Mukhtarov, A. A.; Bobkov, V. V.

    2016-07-01

    The article represents the results of applying various machine learning methods for solving the problem of identifying the edges of a left ventricle area in ultrasound images. The problem of the determination this area consider as a special case of binary classification of pixels. It is shown that the level of correct classification of pixels more than 94.6%. The complex model Bag-10 demonstrates the best result of classification - 98.4%.

  9. Vortex and energy characteristics of flow in the left ventricle following progressive severities of aortic valve regurgitation

    NASA Astrophysics Data System (ADS)

    di Labbio, Giuseppe; Kadem, Lyes

    2016-11-01

    During the heart's filling phase, a notorious vortex is known to develop in the left ventricle (LV). Improper development and poor energetic behavior of this vortex can be correlated with cardiac disease. In particular, during aortic valve regurgitation (leakage of blood through the aortic valve during LV filling), this vortex is forced to interact with a jet emanating from a regurgitant orifice in the valve. The ensuing flow in the left ventricle subject to this disease has yet to be fully characterized and may lead to new indices for evaluation of its severity. As such, this experimental work investigates flow in a model LV subject to aortic regurgitation on a novel double-activation left heart duplicator for six progressive grades of regurgitation (beginning from the healthy case). Double-activation (independent activation of the atrium and ventricle) is critical to the simulation of this pathology. Regurgitation is induced by restricting the closure of the aortic valve to a centralized orifice. The velocity fields for each case are acquired using 2D time-resolved particle image velocimetry. Viscous energy dissipation and vortex formation time are investigated and found to significantly increase as the pathology progresses, while a histogram of vorticity tends toward a shifted and depressed Gaussian distribution. Proper orthogonal decomposition reveals significant disruption of the dominant energetic coherent structures.

  10. Automatic segmentation of the left ventricle in cardiac MRI using local binary fitting model and dynamic programming techniques.

    PubMed

    Hu, Huaifei; Gao, Zhiyong; Liu, Liman; Liu, Haihua; Gao, Junfeng; Xu, Shengzhou; Li, Wei; Huang, Lu

    2014-01-01

    Segmentation of the left ventricle is very important to quantitatively analyze global and regional cardiac function from magnetic resonance. The aim of this study is to develop a novel algorithm for segmenting left ventricle on short-axis cardiac magnetic resonance images (MRI) to improve the performance of computer-aided diagnosis (CAD) systems. In this research, an automatic segmentation method for left ventricle is proposed on the basis of local binary fitting (LBF) model and dynamic programming techniques. The validation experiments are performed on a pool of data sets of 45 cases. For both endo- and epi-cardial contours of our results, percentage of good contours is about 93.5%, the average perpendicular distance are about 2 mm. The overlapping dice metric is about 0.91. The regression and determination coefficient between the experts and our proposed method on the LV mass is 1.038 and 0.9033, respectively; they are 1.076 and 0.9386 for ejection fraction (EF). The proposed segmentation method shows the better performance and has great potential in improving the accuracy of computer-aided diagnosis systems in cardiovascular diseases.

  11. Single primitive ventricle with normally related great arteries and atresia of the left A-V valve.

    PubMed Central

    Coto, E O; Raggio, J M; Malo, P; Sainz, C; Aparisi, R; Gomez-Ullate, J M

    1978-01-01

    A child aged 2 years and 9 months was angiocardiographically diagnosed to have a single ventricle with normally related great arteries and atresia of the left A-V valve. A Blalock-Hanlon procedure and division of a large patent ductus arteriosus were followed by reduction in pulmonary artery pressure, but after operation the patient showed signs of left ventricular failure unresponsive to medical treatment, necessitating pulmonary artery banding. We have found only three similar published cases, and this is the only one with full angiographic documentation. Images PMID:725830

  12. The left ventricle as a mechanical engine: from Leonardo da Vinci to the echocardiographic assessment of peak power output-to-left ventricular mass.

    PubMed

    Dini, Frank L; Guarini, Giacinta; Ballo, Piercarlo; Carluccio, Erberto; Maiello, Maria; Capozza, Paola; Innelli, Pasquale; Rosa, Gian M; Palmiero, Pasquale; Galderisi, Maurizio; Razzolini, Renato; Nodari, Savina

    2013-03-01

    The interpretation of the heart as a mechanical engine dates back to the teachings of Leonardo da Vinci, who was the first to apply the laws of mechanics to the function of the heart. Similar to any mechanical engine, whose performance is proportional to the power generated with respect to weight, the left ventricle can be viewed as a power generator whose performance can be related to left ventricular mass. Stress echocardiography may provide valuable information on the relationship between cardiac performance and recruited left ventricular mass that may be used in distinguishing between adaptive and maladaptive left ventricular remodeling. Peak power output-to-mass, obtained during exercise or pharmacological stress echocardiography, is a measure that reflects the number of watts that are developed by 100 g of left ventricular mass under maximal stimulation. Power output-to-mass may be calculated as left ventricular power output per 100 g of left ventricular mass: 100× left ventricular power output divided by left ventricular mass (W/100 g). A simplified formula to calculate power output-to-mass is as follows: 0.222 × cardiac output (l/min) × mean blood pressure (mmHg)/left ventricular mass (g). When the integrity of myocardial structure is compromised, a mismatch becomes apparent between maximal cardiac power output and left ventricular mass; when this occurs, a reduction of the peak power output-to-mass index is observed.

  13. Chronic effects of a cardiac assist device on the bulk and regional mechanics of the failed left ventricle in goats.

    PubMed

    Nakamura, T; Hayashi, K; Seki, J; Fukuda, S; Noda, H; Nakatani, T; Takano, H; Akutsu, T

    1993-05-01

    Pneumatically driven, diaphragm-type left ventricular assist devices (LVADs) were implanted into 8 goats with profound induced infarction to the left ventricle by using multiple ligations of the left anterior descending (LAD) coronary artery as well as small arteries in the LAD distribution area. Left ventricular diameters, regional myocardial segment lengths, and wall thicknesses were measured by sono-micrometers. After left ventricular function seemed to be recovered, the goats were weaned off the LVADs after a gradual decrease of pump bypass flow over several days. Thereafter, hemodynamic and cardiac parameters were observed for about 1 month more. Three animals recovered successfully owing to the LVAD pumping. Before starting pump-weaning procedures, the bulk mechanical work (BMW) done by the left ventricle during LVAD pumping and under temporary pump-off conditions was 0.08 +/- 0.01 (mean +/- SE) and 0.22 +/- 0.01 W/100 g left ventricular weight (LVW), respectively, while the regional mechanical work done by the normal myocardium (RMWn) was 1.5 +/- 0.4 and 4.3 +/- 0.9 mW/cm3 during pumping and under temporary pump-off conditions, respectively. BMW and RMWn values obtained under pump-on conditions both increased gradually during the weaning process. Even after pump removal, they continued to increase and reached constant values of about 0.3 W/100 g LVW and 10 mW/cm3, respectively, around 2 weeks after pump removal. Although the myocardium in the infarction area did no work for the first several days after surgery, it recovered to do some external work with the aid of LVAD pumping. However, recovery of left ventricular function owed more to compensatory increases in pumping ability of the remaining normal myocardium than to recovery of the damaged myocardium. The LVAD could salvage severely damaged hearts unless the infarction area exceeded 50% of the left ventricular wall.

  14. Methylome analysis reveals alterations in DNA methylation in the regulatory regions of left ventricle development genes in human dilated cardiomyopathy.

    PubMed

    Jo, Bong-Seok; Koh, In-Uk; Bae, Jae-Bum; Yu, Ho-Yeong; Jeon, Eun-Seok; Lee, Hae-Young; Kim, Jae-Joong; Choi, Murim; Choi, Sun Shim

    2016-08-01

    Dilated cardiomyopathy (DCM) is one of the main causes of heart failure (called cardiomyopathies) in adults. Alterations in epigenetic regulation (i.e., DNA methylation) have been implicated in the development of DCM. Here, we identified a total of 1828 differentially methylated probes (DMPs) using the Infinium 450K HumanMethylation Bead chip by comparing the methylomes between 18 left ventricles and 9 right ventricles. Alterations in DNA methylation levels were observed mainly in lowly methylated regions corresponding to promoter-proximal regions, which become hypermethylated in severely affected left ventricles. Subsequent mRNA microarray analysis showed that the effect of DNA methylation on gene expression regulation is not unidirectional but is controlled by the functional sub-network context. DMPs were significantly enriched in the transcription factor binding sites (TFBSs) we tested. Alterations in DNA methylation were specifically enriched in the cis-regulatory regions of cardiac development genes, the majority of which are involved in ventricular development (e.g., TBX5 and HAND1). Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  15. The association of ideal cardiovascular health and left ventricle hypertrophy in rural population of northeast China

    PubMed Central

    Chang, Ye; Li, Yuan; Guo, Xiaofan; Li, Tan; Chen, Yintao; Dai, Dongxue; Sun, Yingxian

    2017-01-01

    Abstract In 2010, the American Heart Association (AHA) published a new concept “ideal cardiovascular health” (CVH), which consisted of 4 behaviors (smoking, body mass index [BMI], physical activity, and diet score) and 3 health factors (total cholesterol [TC], blood pressure [BP], and fasting plasma glucose [FPG]). This study was aimed to investigate the association between CVH with left ventricle hypertrophy (LVH) in a rural general population. From January 2012 to August 2013, we conducted this cross-sectional study using a multi-stage cluster sampling method. A representative sample of individuals who were at 35 years or older was selected. All the 7 CVH metrics were estimated for ideal, intermediate, and poor levels. LVH was accessed by echocardiography and classified into concentric remodeling, concentric LVH, and eccentric LVH. The association between CVH and LVH was determined. The final data were obtained from 10,684 adults (5497 men and 5187 women) in the rural areas of northeast China. Overall, the prevalence rates of concentric remodeling, concentric LVH, and eccentric LVH were 5.1%, 4.9%, and 12.8%, respectively. The prevalence of concentric/eccentric LVH was inversely related to the numbers of ideal CVH metrics. Multivariate logistic regression analysis indicated that only poor BP was associated with concentric remodeling among the 7 CVH metrics; poor BP was highly associated with concentric LVH (OR: 8.49; 95% CI: 4.59–15.7); poor BMI was highly associated with eccentric LVH (OR: 5.87; 95% CI: 4.83–7.14). Compared to subjects with 5 to 7 ideal CVH metrics, subjects with 4, 3, 2, 1, and 0 ideal CVH metrics had an increased risk for both concentric and eccentric LVH in a number-dependent manner. The subjects with poor CVH status had a 5.90-fold higher risk of developing concentric LVH and a 3.24-fold higher risk of developing eccentric LVH, compared to subjects with ideal-intermediate CVH. Our study found that an inversely gradient relationship

  16. Graph cut-based method for segmenting the left ventricle from MRI or echocardiographic images.

    PubMed

    Bernier, Michael; Jodoin, Pierre-Marc; Humbert, Olivier; Lalande, Alain

    2017-04-02

    In this paper, we present a fast and interactive graph cut method for 3D segmentation of the endocardial wall of the left ventricle (LV) adapted to work on two of the most widely used modalities: magnetic resonance imaging (MRI) and echocardiography. Our method accounts for the fundamentally different nature of both modalities: 3D echocardiographic images have a low contrast, a poor signal-to-noise ratio and frequent signal drop, while MR images are more detailed but also cluttered and contain highly anisotropic voxels. The main characteristic of our method is to work in a 3D Bezier coordinate system instead of the original Euclidean space. This comes with several advantages, including an implicit shape prior and a result guarantied not to have any holes in it. The proposed method is made of 4 steps. First, a 3D sampling of the LV cavity is made based on a Bezier coordinate system. This allows to warp the input 3D image to a Bezier space in which a plane corresponds to an anatomically plausible 3D Euclidean bullet shape. Second, a 3D graph is built and an energy term (which is based on the image gradient and a 3D probability map) is assigned to each edge of the graph, some of which being given an infinite energy to ensure the resulting 3D structure passes through key anatomical points. Third, a max-flow min-cut procedure is executed on the energy graph to delineate the endocardial surface. And fourth, the resulting surface is projected back to the Euclidean space where a post-processing convex hull algorithm is applied on every short axis slice to remove local concavities. Results obtained on two datasets reveal that our method takes between 2 and 5s to segment a 3D volume, it has better results overall than most state-of-the-art methods on the CETUS echocardiographic dataset and is statistically as good as a human operator on MR images.

  17. Electrophysiologic remodeling of the left ventricle in pressure overload-induced right ventricular failure.

    PubMed

    Hardziyenka, Maxim; Campian, Maria E; Verkerk, Arie O; Surie, Sulaiman; van Ginneken, Antoni C G; Hakim, Sara; Linnenbank, André C; de Bruin-Bon, H A C M Rianne; Beekman, Leander; van der Plas, Mart N; Remme, Carol A; van Veen, Toon A B; Bresser, Paul; de Bakker, Jacques M T; Tan, Hanno L

    2012-06-12

    The purpose of this study was to analyze the electrophysiologic remodeling of the atrophic left ventricle (LV) in right ventricular (RV) failure (RVF) after RV pressure overload. The LV in pressure-induced RVF develops dysfunction, reduction in mass, and altered gene expression, due to atrophic remodeling. LV atrophy is associated with electrophysiologic remodeling. We conducted epicardial mapping in Langendorff-perfused hearts, patch-clamp studies, gene expression studies, and protein level studies of the LV in rats with pressure-induced RVF (monocrotaline [MCT] injection, n = 25; controls with saline injection, n = 18). We also performed epicardial mapping of the LV in patients with RVF after chronic thromboembolic pulmonary hypertension (CTEPH) (RVF, n = 10; no RVF, n = 16). The LV of rats with MCT-induced RVF exhibited electrophysiologic remodeling: longer action potentials (APs) at 90% repolarization and effective refractory periods (ERPs) (60 ± 1 ms vs. 44 ± 1 ms; p < 0.001), and slower longitudinal conduction velocity (62 ± 2 cm/s vs. 70 ± 1 cm/s; p = 0.003). AP/ERP prolongation agreed with reduced Kcnip2 expression, which encodes the repolarizing potassium channel subunit KChIP2 (0.07 ± 0.01 vs. 0.11 ± 0.02; p < 0.05). Conduction slowing was not explained by impaired impulse formation, as AP maximum upstroke velocity, whole-cell sodium current magnitude/properties, and mRNA levels of Scn5a were unaltered. Instead, impulse transmission in RVF was hampered by reduction in cell length (111.6 ± 0.7 μm vs. 122.0 ± 0.4 μm; p = 0.02) and width (21.9 ± 0.2 μm vs. 25.3 ± 0.3 μm; p = 0.002), and impaired cell-to-cell impulse transmission (24% reduction in Connexin-43 levels). The LV of patients with CTEPH with RVF also exhibited ERP prolongation (306 ± 8 ms vs. 268 ± 5 ms; p = 0.001) and conduction slowing (53 ± 3 cm/s vs. 64 ± 3 cm/s; p = 0.005). Pressure-induced RVF is associated with electrophysiologic remodeling of the atrophic LV. Copyright

  18. Finite Element Interface to Linear Solvers

    SciTech Connect

    Williams, Alan

    2005-03-18

    Sparse systems of linear equations arise in many engineering applications, including finite elements, finite volumes, and others. The solution of linear systems is often the most computationally intensive portion of the application. Depending on the complexity of problems addressed by the application, there may be no single solver capable of solving all of the linear systems that arise. This motivates the desire to switch an application from one solver librwy to another, depending on the problem being solved. The interfaces provided by solver libraries differ greatly, making it difficult to switch an application code from one library to another. The amount of library-specific code in an application Can be greatly reduced by having an abstraction layer between solver libraries and the application, putting a common "face" on various solver libraries. One such abstraction layer is the Finite Element Interface to Linear Solvers (EEl), which has seen significant use by finite element applications at Sandia National Laboratories and Lawrence Livermore National Laboratory.

  19. The GPRIME approach to finite element modeling

    NASA Technical Reports Server (NTRS)

    Wallace, D. R.; Mckee, J. H.; Hurwitz, M. M.

    1983-01-01

    GPRIME, an interactive modeling system, runs on the CDC 6000 computers and the DEC VAX 11/780 minicomputer. This system includes three components: (1) GPRIME, a user friendly geometric language and a processor to translate that language into geometric entities, (2) GGEN, an interactive data generator for 2-D models; and (3) SOLIDGEN, a 3-D solid modeling program. Each component has a computer user interface of an extensive command set. All of these programs make use of a comprehensive B-spline mathematics subroutine library, which can be used for a wide variety of interpolation problems and other geometric calculations. Many other user aids, such as automatic saving of the geometric and finite element data bases and hidden line removal, are available. This interactive finite element modeling capability can produce a complete finite element model, producing an output file of grid and element data.

  20. Model Reduction of Viscoelastic Finite Element Models

    NASA Astrophysics Data System (ADS)

    Park, C. H.; Inman, D. J.; Lam, M. J.

    1999-01-01

    This paper examines a method of adding viscoelastic properties to finite element models by using additional co-ordinates to account for the frequency dependence usually associated with such damping materials. Several such methods exist and all suffer from an increase in order of the final finite model which is undesirable in many applications. Here we propose to combine one of these methods, the GHM (Golla-Hughes-McTavish) method, with model reduction techniques to remove the objection of increased model order. The result of combining several methods is an ability to add the effects of visoelastic components to finite element or other analytical models without increasing the order of the system. The procedure is illustrated by a numerical example. The method proposed here results in a viscoelastic finite element of a structure without increasing the order of the original model.

  1. Finite element modeling and analysis of tires

    NASA Technical Reports Server (NTRS)

    Noor, A. K.; Andersen, C. M.

    1983-01-01

    Predicting the response of tires under various loading conditions using finite element technology is addressed. Some of the recent advances in finite element technology which have high potential for application to tire modeling problems are reviewed. The analysis and modeling needs for tires are identified. Reduction methods for large-scale nonlinear analysis, with particular emphasis on treatment of combined loads, displacement-dependent and nonconservative loadings; development of simple and efficient mixed finite element models for shell analysis, identification of equivalent mixed and purely displacement models, and determination of the advantages of using mixed models; and effective computational models for large-rotation nonlinear problems, based on a total Lagrangian description of the deformation are included.

  2. Visualizing higher order finite elements. Final report

    SciTech Connect

    Thompson, David C; Pebay, Philippe Pierre

    2005-11-01

    This report contains an algorithm for decomposing higher-order finite elements into regions appropriate for isosurfacing and proves the conditions under which the algorithm will terminate. Finite elements are used to create piecewise polynomial approximants to the solution of partial differential equations for which no analytical solution exists. These polynomials represent fields such as pressure, stress, and momentum. In the past, these polynomials have been linear in each parametric coordinate. Each polynomial coefficient must be uniquely determined by a simulation, and these coefficients are called degrees of freedom. When there are not enough degrees of freedom, simulations will typically fail to produce a valid approximation to the solution. Recent work has shown that increasing the number of degrees of freedom by increasing the order of the polynomial approximation (instead of increasing the number of finite elements, each of which has its own set of coefficients) can allow some types of simulations to produce a valid approximation with many fewer degrees of freedom than increasing the number of finite elements alone. However, once the simulation has determined the values of all the coefficients in a higher-order approximant, tools do not exist for visual inspection of the solution. This report focuses on a technique for the visual inspection of higher-order finite element simulation results based on decomposing each finite element into simplicial regions where existing visualization algorithms such as isosurfacing will work. The requirements of the isosurfacing algorithm are enumerated and related to the places where the partial derivatives of the polynomial become zero. The original isosurfacing algorithm is then applied to each of these regions in turn.

  3. A level set approach for left ventricle detection in CT images using shape segmentation and optical flow

    NASA Astrophysics Data System (ADS)

    Brieva, Jorge; Moya-Albor, Ernesto; Escalante-Ramírez, Boris

    2015-01-01

    The left ventricle (LV) segmentation plays an important role in a subsequent process for the functional analysis of the LV. Typical segmentation of the endocardium wall in the ventricle excludes papillary muscles which leads to an incorrect measure of the ejected volume in the LV. In this paper we present a new variational strategy using a 2D level set framework that includes a local term for enhancing the low contrast structures and a 2D shape model. The shape model in the level set method is propagated to all image sequences corresponding to the cardiac cycles through the optical flow approach using the Hermite transform. To evaluate our strategy we use the Dice index and the Hausdorff distance to compare the segmentation results with the manual segmentation carried out by the physician.

  4. Tissue Doppler imaging in the left ventricle and right ventricle in healthy children: normal age-related peak systolic velocities, timings, and time differences.

    PubMed

    van der Hulst, Annelies E; Delgado, Victoria; Ten Harkel, Arend D J; Klitsie, Liselotte M; Filippini, Luc H P M; Bax, Jeroen J; Blom, Nico A; Roest, Arno A W

    2011-12-01

    Tissue Doppler imaging (TDI) enables assessment of velocities and timings within the left (LV) and the right (RV) ventricle with high temporal resolution. Knowledge on normal age-related values of peak systolic velocities and timings in healthy children may optimize the benefit of device-based therapies in paediatric patients with heart failure. A total of 123 healthy children (from 1 month to 18 years old) underwent TDI evaluation of the RV and LV. Peak systolic velocity and time to peak systolic velocity were assessed at the basal LV lateral wall, inter-ventricular septum (IVS), RV free wall (RVFW), and at the RV outflow tract (RVOT). Intra-ventricular time differences were calculated. Regression analysis was performed to assess the age dependency of the ventricular mechanics. Median peak velocities were: LV lateral wall: 6.3 cm/s (inter-quartile range (IQR): 5.1-7.9 cm/s); IVS: 6.0 cm/s (5.4-6.7 cm/s); RVFW: 10.2 cm/s (8.9-11.3 cm/s); RVOT: 7.2 cm/s (6.0-8.2 cm/s). Timings of peak systolic velocities were: LV lateral wall: 101 ms (91-112 ms); IVS: 114 ms (100-128 ms); RVFW: 177 ms (157-194 ms); RVOT: 100 ms (88-113 ms). Timings and peak velocities significantly increased with age at both ventricles. No relevant time difference was observed within the LV, whereas a considerable time delay was observed within the RV between the RVFW and the IVS (62 ms, IQR: 45-74 ms) and between the RVFW and the RVOT (74 ms, IQR: 59-93 ms). The present evaluation provides TDI-derived physiological values on normal LV and RV mechanics of healthy children. Within the LV, no relevant time difference was observed, whereas a considerable mechanical delay is observed within the healthy RV.

  5. Finite Element Analysis of Pipe Elbows.

    DTIC Science & Technology

    1980-02-01

    AD-AO81 077 DAVD TAYLOR NAVAL SHIP RESEARCH AND DEVELOPMENT CE--ETC F/B 13/11 FINITE ELEMENT ANALYSIS OF PIPE ELBOWS .(U) FE SO M S MARCUS, B C...TAYLOR NAVAL SHIP i RESEARCH AND DEVELOPMENT CENTER Bethesda, Md. 20084 4 FINITE ELEMENT ANALYSIS OF PIPE ELBOWS by 0 Melvyn S. Marcus and Gordon C...a 90-degree pipe elbow to determine principal stresses due to internal pressure, inplane bending, out-of-plane bending, and torsion moment loadings

  6. Quadratic finite elements and incompressible viscous flows.

    SciTech Connect

    Dohrmann, Clark R.; Gartling, David K.

    2005-01-01

    Pressure stabilization methods are applied to higher-order velocity finite elements for application to viscous incompressible flows. Both a standard pressure stabilizing Petrov-Galerkin (PSPG) method and a new polynomial pressure projection stabilization (PPPS) method have been implemented and tested for various quadratic elements in two dimensions. A preconditioner based on relaxing the incompressibility constraint is also tested for the iterative solution of saddle point problems arising from mixed Galerkin finite element approximations to the Navier-Stokes equations. The preconditioner is demonstrated for BB stable elements with discontinuous pressure approximations in two and three dimensions.

  7. Finite-element models of continental extension

    NASA Technical Reports Server (NTRS)

    Lynch, H. David; Morgan, Paul

    1990-01-01

    Numerical models of the initial deformation of extending continental lithosphere, computed to investigate the control of preexisting thermal and mechanical heterogeneities on the style of deformation, are presented. The finite element method is used to calculate deformation with a viscoelastic-plastic model for the lithosphere. Comparisons of the results of analytic models and finite-element models using this method show that good results may be obtained by the numerical technique, even with elements containing both brittle and viscoelastic sampling points. It is shown that the gross style of initial extensional deformation is controlled by the depth and width of the initial heterogeneity which localizes deformation.

  8. Finite element methods for high speed flows

    NASA Technical Reports Server (NTRS)

    Loehner, R.; Morgan, K.; Peraire, J.; Zienkiewicz, O. C.

    1985-01-01

    An explicit finite element based solution procedure for solving the equations of compressible viscous high speed flow is presented. The method uses domain splitting to advance the solution with different timesteps on different portions of the mesh. For steady inviscid flows, adaptive mesh refinement procedures are successfully employed to enhance the definition of discontinuities. Preliminary ideas on the application of adaptive mesh refinement to the solution of problems involving steady viscous flow are presented. Sample timings are given for the performance of the finite element code on modern supercomputers.

  9. Automatic segmentation of the left ventricle and computation of diagnostic parameters using regiongrowing and a statistical model

    NASA Astrophysics Data System (ADS)

    Fritz, Dominik; Rinck, Daniel; Unterhinninghofen, Roland; Dillmann, Ruediger; Scheuering, Michael

    2005-04-01

    The manual segmentation and analysis of high-resolution multi-slice cardiac CT datasets is both labor intensive and time consuming. Therefore it is necessary to supply the cardiologist with powerful software tools to segment the myocardium and compute the relevant diagnostic parameters. In this work we present an semi-automatic cardiac segmentation approach with minimal user interaction. It is based on a combination of an adaptive slice-based regiongrowing and a modified Active Shape Model (ASM). Starting with a single manual click point in the ascending aorta, the aorta, the left atrium and the left ventricle get segmented with the slice-based adaptive regiongrowing. The approximate position of the aortic and mitral valve as well as the principal axes of the left ventricle (LV) are determined. To prevent the regiongrowing from draining into neighboring anatomical structures via CT artifacts, we implemented a draining control by examining a cubic region around the currently processed voxel. Additionally, we use moment-based parameters to integrate simple anatomical knowledge into the regiongrowing process. Using the results of the preceding regiongrowing process, a ventricle-centric and normalized coordinate system is established which is used to adapt a previously trained ASM to the image, using an iterative multi-resolution approach. After fitting the ASM to the image, we can use the generated model-points to create an exact surface model of the left ventricular myocardium for visualization and for computing the diagnostically relevant parameters, like the ventricular blood volume and the myocardial wall thickness.

  10. Endocardial left ventricle feature tracking and reconstruction from tri-plane trans-esophageal echocardiography data

    NASA Astrophysics Data System (ADS)

    Dangi, Shusil; Ben-Zikri, Yehuda K.; Cahill, Nathan; Schwarz, Karl Q.; Linte, Cristian A.

    2015-03-01

    Two-dimensional (2D) ultrasound (US) has been the clinical standard for over two decades for monitoring and assessing cardiac function and providing support via intra-operative visualization and guidance for minimally invasive cardiac interventions. Developments in three-dimensional (3D) image acquisition and transducer design and technology have revolutionized echocardiography imaging enabling both real-time 3D trans-esophageal and intra-cardiac image acquisition. However, in most cases the clinicians do not access the entire 3D image volume when analyzing the data, rather they focus on several key views that render the cardiac anatomy of interest during the US imaging exam. This approach enables image acquisition at a much higher spatial and temporal resolution. Two such common approaches are the bi-plane and tri-plane data acquisition protocols; as their name states, the former comprises two orthogonal image views, while the latter depicts the cardiac anatomy based on three co-axially intersecting views spaced at 600 to one another. Since cardiac anatomy is continuously changing, the intra-operative anatomy depicted using real-time US imaging also needs to be updated by tracking the key features of interest and endocardial left ventricle (LV) boundaries. Therefore, rapid automatic feature tracking in US images is critical for three reasons: 1) to perform cardiac function assessment; 2) to identify location of surgical targets for accurate tool to target navigation and on-target instrument positioning; and 3) to enable pre- to intra-op image registration as a means to fuse pre-op CT or MR images used during planning with intra-operative images for enhanced guidance. In this paper we utilize monogenic filtering, graph-cut based segmentation and robust spline smoothing in a combined work flow to process the acquired tri-plane TEE time series US images and demonstrate robust and accurate tracking of the LV endocardial features. We reconstruct the endocardial LV

  11. Studies of finite element analysis of composite material structures

    NASA Technical Reports Server (NTRS)

    Douglas, D. O.; Holzmacher, D. E.; Lane, Z. C.; Thornton, E. A.

    1975-01-01

    Research in the area of finite element analysis is summarized. Topics discussed include finite element analysis of a picture frame shear test, BANSAP (a bandwidth reduction program for SAP IV), FEMESH (a finite element mesh generation program based on isoparametric zones), and finite element analysis of a composite bolted joint specimens.

  12. Assignment Of Finite Elements To Parallel Processors

    NASA Technical Reports Server (NTRS)

    Salama, Moktar A.; Flower, Jon W.; Otto, Steve W.

    1990-01-01

    Elements assigned approximately optimally to subdomains. Mapping algorithm based on simulated-annealing concept used to minimize approximate time required to perform finite-element computation on hypercube computer or other network of parallel data processors. Mapping algorithm needed when shape of domain complicated or otherwise not obvious what allocation of elements to subdomains minimizes cost of computation.

  13. Finite element analysis applied to cornea reshaping.

    PubMed

    Cabrera Fernández, Delia; Niazy, A M; Kurtz, R M; Djotyan, G P; Juhasz, T

    2005-01-01

    A 2-D finite element model of the cornea is developed to simulate corneal reshaping and the resulting deformation induced by refractive surgery. In the numerical simulations, linear and nonlinear elastic models are applied when stiffness inhomogeneities varying with depth are considered. Multiple simulations are created that employ different geometric configurations for the removal of the corneal tissue. Side-by-side comparisons of the different constitutive laws are also performed. To facilitate the comparison, the material property constants are identified from the same experimental data, which are obtained from mechanical tests on corneal strips and membrane inflation experiments. We then validate the resulting models by comparing computed refractive power changes with clinical results. Tissue deformations created by simulated corneal tissue removal using finite elements are consistent with clinically observed postsurgical results. The model developed provides a much more predictable refractive outcome when the stiffness inhomogeneities of the cornea and nonlinearities of the deformations are included in the simulations. Finite element analysis is a useful tool for modeling surgical effects on the cornea and developing a better understanding of the biomechanics of the cornea. The creation of patient-specific simulations would allow surgical outcomes to be predicted based on individualized finite element models.

  14. Finite element displacement analysis of a lung.

    NASA Technical Reports Server (NTRS)

    Matthews, F. L.; West, J. B.

    1972-01-01

    A method is given based on the technique of finite elements which determines theoretically the mechanical behavior of a lung-shaped body loaded by its own weight. The results of this theoretical analysis have been compared with actual measurements of alveolar size and pleural pressures in animal lungs.

  15. Assignment Of Finite Elements To Parallel Processors

    NASA Technical Reports Server (NTRS)

    Salama, Moktar A.; Flower, Jon W.; Otto, Steve W.

    1990-01-01

    Elements assigned approximately optimally to subdomains. Mapping algorithm based on simulated-annealing concept used to minimize approximate time required to perform finite-element computation on hypercube computer or other network of parallel data processors. Mapping algorithm needed when shape of domain complicated or otherwise not obvious what allocation of elements to subdomains minimizes cost of computation.

  16. Finite element modelling of acoustic emission sensor

    NASA Astrophysics Data System (ADS)

    Gerasimov, S. I.; Sych, T. V.

    2017-08-01

    With a validated finite element system COSMOS/M, the out-of-plane displacements corresponding to model sources of acoustic emission (AE) were calculated in three-dimensional samples. The displacement signals were calculated for positions of the receiver on the top plate surface at several different distances (in the far-field) from the source’s epicenter.

  17. Intrinsic Myoarchitectural Differences Between the Left and Right Ventricles of Fetal Human Hearts: An Ultrasonic Backscatter Feasibility Study

    PubMed Central

    Holland, Mark R.; Gibson, Allyson A.; Kirschner, Carol A.; Hicks, Deborah; Ludomirsky, Achiau; Singh, Gautam K.

    2009-01-01

    Summary Embryologically, cardiac chambers differ in their morphological and contractile properties from the beginning. We hypothesized that a non-invasive ultrasonic backscatter investigation might illustrate the fundamental differences in myocardial morphologic properties of the two ventricles during heart development. Objectives The goals of this investigation were: 1) to explore the feasibility of measuring the magnitude of cyclic variation of ultrasonic backscatter from the left and right ventricular free walls of fetal hearts; 2) to compare measurements of the magnitude of cyclic variation from the left and right sides of the heart; and 3) to determine if the observed results are consistent with predictions relating the overall backscatter level and the magnitude of cyclic variation. Methods Cyclic variation data from the left and right ventricular free walls were generated from analyses of the backscatter from echocardiographic images of 16 structurally normal fetal hearts at mid-gestation. Results The magnitude of cyclic variation was found to be greater for the left ventricular free wall than for the right ventricular free wall (4.5 ± 1.1 dB vs. 2.3 ± 0.9 dB, respectively; mean ± SD; p < 0.0001, paired t-test). Conclusion Measurements of the cyclic variation of backscatter can be obtained from both the left and right sides of fetal hearts demonstrating a significant difference between the measured magnitude of cyclic variation in the left and right ventricular myocardium. This observation is consistent with predictions relating the overall backscatter level and the magnitude of cyclic variation. Results of this study suggest cyclic variation measurements may offer a useful approach for characterizing intrinsic differences in myocardial properties of the two ventricles in assessing fetal heart development. PMID:19131208

  18. Evaluation of diastolic filling of left ventricle in health and disease: Doppler echocardiography is the clinician's Rosetta Stone.

    PubMed

    Nishimura, R A; Tajik, A J

    1997-07-01

    Abnormalities of diastolic function have a major role in producing the signs and symptoms of heart failure. However, diastolic function of the heart is a complex sequence of multiple interrelated events, and it has been difficult to understand, diagnose and treat the various abnormalities of diastolic filling that occur in patients with heart disease. Recently, Doppler echocardiography has been used to examine the different diastolic filling patterns of the left ventricle in health and disease, but confusion about diagnosis and treatment options has arisen because of the misinterpretation of these flow velocity curves. This review presents a simplified approach to understanding the process of diastolic filling of the left ventricle and interpreting the Doppler flow velocity curves as they relate to this process. It has been hypothesized that transmitral flow velocity curves show a progression over time with diseases involving the myocardium. This concept can be applied clinically to estimate left ventricular filling pressures and to predict prognosis in selected groups of patients. Specific therapy for diastolic dysfunction based on Doppler flow velocity curves is discussed.

  19. A tissue-level electromechanical model of the left ventricle: application to the analysis of intraventricular pressure.

    PubMed

    Le Rolle, Virginie; Carrault, Guy; Richard, Pierre-Yves; Pibarot, Philippe; Durand, Louis-Gilles; Hernández, Alfredo I

    2009-12-01

    The ventricular pressure profile is characteristic of the cardiac contraction progress and is useful to evaluate the cardiac performance. In this contribution, a tissue-level electromechanical model of the left ventricle is proposed, to assist the interpretation of left ventricular pressure waveforms. The left ventricle has been modeled as an ellipsoid composed of twelve mechano-hydraulic sub-systems. The asynchronous contraction of these twelve myocardial segments has been represented in order to reproduce a realistic pressure profiles. To take into account the different energy domains involved, the tissue-level scale and to facilitate the building of a modular model, multiple formalisms have been used: Bond Graph formalism for the mechano-hydraulic aspects and cellular automata for the electrical activation. An experimental protocol has been defined to acquire ventricular pressure signals from three pigs, with different afterload conditions. Evolutionary Algorithms have been used to identify the model parameters in order to minimize the error between experimental and simulated ventricular pressure signals. Simulation results show that the model is able to reproduce experimental ventricular pressure. In addition, electro-mechanical activation times have been determined in the identification process. For example, the maximum electrical activation time is reached, respectively, 96.5, 139.3 and 131.5 ms for the first, second, and third pigs. These preliminary results are encouraging for the application of the model on non-invasive data like ECG, arterial pressure or myocardial strain.

  20. Catheter-based high-intensity ultrasound for epicardial ablation of the left ventricle: device design and in vivo feasiblity

    NASA Astrophysics Data System (ADS)

    Salgaonkar, Vasant A.; Nazer, Babak; Jones, Peter D.; Tanaka, Yasuaki; Martin, Alastair; Ng, Bennett; Duggirala, Srikant; Diederich, Chris J.; Gerstenfeld, Edward P.

    2015-03-01

    The development and in vivo testing of a high-intensity ultrasound thermal ablation catheter for epicardial ablation of the left ventricle (LV) is presented. Scar tissue can occur in the mid-myocardial and epicardial space in patients with nonischemic cardiomyopathy and lead to ventricular tachycardia. Current ablation technology uses radiofrequency energy, which is limited epicardially by the presence of coronary vessels, phrenic nerves, and fat. Ultrasound energy can be precisely directed to deliver targeted deep epicardial ablation while sparing intervening epicardial nerve and vessels. The proof-of-concept ultrasound applicators were designed for sub-xyphoid access to the pericardial space through a steerable 14-Fr sheath. The catheter consists of two rectangular planar transducers, for therapy (6.4 MHz) and imaging (5 MHz), mounted at the tip of a 3.5-mm flexible nylon catheter coupled and encapsulated within a custom-shaped balloon for cooling. Thermal lesions were created in the LV in a swine (n = 10) model in vivo. The ultrasound applicator was positioned fluoroscopically. Its orientation and contact with the LV were verified using A-mode imaging and a radio-opaque marker. Ablations employed 60-s exposures at 15 - 30 W (electrical power). Histology indicated thermal coagulation and ablative lesions penetrating 8 - 12 mm into the left ventricle on lateral and anterior walls and along the left anterior descending artery. The transducer design enabled successful sparing from the epicardial surface to 2 - 4 mm of intervening ventricle tissue and epicardial fat. The feasibility of targeted epicardial ablation with catheter-based ultrasound was demonstrated.

  1. Left Ventricle Fibrosis Associated With Nonsustained Ventricular Tachycardia in an Elite Athlete: Is Exercise Responsible? A Case Report

    PubMed Central

    Poussel, Mathias; Djaballah, Karim; Laroppe, Julien; Brembilla-Perrot, Béatrice; Marie, Pierre-Yves; Chenuel, Bruno

    2012-01-01

    Objective: To emphasize the potentially harmful effects of high-intensity exercise on cardiac health and the fine line between physiologic and pathologic adaptation to chronic exercise in the elite athlete. This case also highlights the crucial need for regular evaluation of symptoms that suggest cardiac abnormality in athletes. Background: Sudden cardiac death (SCD) of young athletes is always a tragedy because they epitomize health. However, chronic, high-intensity exercise sometimes has harmful effects on cardiac health, and pathologic changes, such as myocardial fibrosis, have been observed in endurance athletes. In this case, a highly trained 30-year-old cyclist reported brief palpitations followed by presyncope feeling while exercising. Immediate investigations revealed nonsustained ventricular tachycardia originating from the left ventricle on a stress test associated with myocardial fibrosis of the left ventricle as shown with magnetic resonance imaging. Despite complete cessation of exercise, life-threatening arrhythmia and fibrosis persisted, leading to complete restriction from competition. Differential Diagnosis: Hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, myocarditis, postmyocarditis, use of drugs and toxic agents, doping, and systemic disease. Treatment: The arrhythmia could not be treated with catheter ablation procedure or drug suppression. Therefore, the athlete was instructed to withdraw completely from sport participation and to have a medical follow-up twice each year. Uniqueness: To our knowledge, no other report of left ventricle exercise-induced fibrosis associated with life-threatening arrhythmia in a living young elite athlete exists. Only postmortem evidence supports such myocardial pathologic adaptation to exercise. Conclusions: To prevent SCD in young athletes, careful attention must be paid to exercise-related symptoms that suggest a cardiac abnormality because they more often are linked to life

  2. Cardiovascular morphometry with high-resolution 3D magnetic resonance: First application to left ventricle diastolic dysfunction.

    PubMed

    Gallo, Diego; Vardoulis, Orestis; Monney, Pierre; Piccini, Davide; Antiochos, Panagiotis; Schwitter, Juerg; Stergiopulos, Nikolaos; Morbiducci, Umberto

    2017-09-01

    In this study, an image-based morphometry toolset quantifying geometric descriptors of the left ventricle, aorta and their coupling is applied to investigate whether morphological information can differentiate between subjects affected by diastolic dysfunction (patient group) and their age-matched controls (control group). The ventriculo-aortic region of 20 total participants (10 per group) were segmented from high-resolution 3D magnetic resonance images, from the left ventricle to the descending aorta. Each geometry was divided into segments in correspondence of anatomical landmarks. The orientation of each segment was estimated by least-squares fitting of the respective centerline segment to a plane. Curvature and torsion of vessels' centerlines were automatically extracted, and aortic arch was characterized in terms of height and width. Tilt angle between subsequent best-fit planes in the left ventricle and ascending aorta regions, curvature and cross-sectional area in the descending aorta resulted significantly different between patient and control groups (P-values< 0.05). Aortic volume (P = 0.04) and aortic arch width (P = 0.03) resulted significantly different between the two groups. The observed morphometric differences underlie differences in hemodynamics, by virtue of the influence of geometry on blood flow patterns. The present exploratory analysis does not determine if aortic geometric changes precede diastolic dysfunction, or vice versa. However, this study (1) underlines differences between healthy and diastolic dysfunction subjects, and (2) provides geometric parameters that might help to determine early aortic geometric alterations and potentially prevent evolution toward advanced diastolic dysfunction. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

  3. Finite Element Simulation of Smart Structures

    NASA Technical Reports Server (NTRS)

    Cui, Y. Lawrence; Panahandeh, M.

    1996-01-01

    Finite element equations representing the behavior of piezoelectric materials when bounded to a typical structure and used as sensors and actuators were developed. Emphasis was placed on generating sensor output equations of piezoelectric sensors and responses of a typical structure bonded with piezoelectric sensors and actuators on the basis of finite element formulation. The model can predict not only structural responses due to both mechanical and electrical loading but also electrical potential due to mechanical or thermal effects. The resulted finite element equations were then used for simple control design and performance evaluation. In the control algorithm, voltages coming out from piezoelectric sensors, which are proportional to strains at sensing locations, are taken as input. The voltages applied to the piezoelectric actuators are used as output. The feasibility of integrating control algorithm with the element routine developed herein and FEAP was demonstrated. In particular, optimal independent modal space control was implemented in a software package on the basis of finite element formulation. A rudimentary finite element-control algorithm package was also developed to evaluate the performance of candidate control laws. A few numerical simulations using the software package developed herein were given. The integrated software package will provide a design tool to address issues such as how adaptive smart systems will scale to a full size aircraft, the amount of piezoelectric materials and the powers needed to actuate it for desired performance. It will also provide a viable new structural control design concept for practical applications in large flexible structures such as aerospace vehicles and aircraft.

  4. Intravascular stenting of systemic venous baffle stenosis after corrective surgery for double outlet right ventricle with left isomerism

    PubMed Central

    Miura, T.; Sano, T.; Matsuda, H.

    1999-01-01

    A 14 year old girl with double outlet right ventricle, left isomerism, and complicated atrial anatomy had undergone corrective surgery with intra-atrial rerouting at 5 years of age. Cardiac catheterisation eight years after the surgery showed that she had two systemic venous baffle stenoses: between the hepatic vein and caval vein, and the caval vein and right atrium. Two Palmaz stents were successfully implanted percutaneously through a long sheath and a balloon catheter. The stenoses were relieved immediately and her symptoms quickly disappeared.

 Keywords: stents; congenital heart defects; baffle stenoses PMID:9922365

  5. Ectopia cordis with a double outlet right ventricle, large ventricular septal defect, malposed great arteries and left ventricular hypoplasia.

    PubMed

    Malik, Rabiya; Zilberman, Mark V; Tang, Liwen; Miller, Susan; Pandian, Natesa G

    2015-03-01

    Ectopia cordis, defined as partial or complete displacement of the heart outside of the thoracic cavity, is a rare congenital malformation. If not surgically corrected during the early years of life, ectopia cordis can prove to be a fatal abnormality. However, due to the presence of multiple intracardiac and extracardiac malformations, a corrective surgery might not always be successful. The pathology of ectopia cordis with a double outlet right ventricle, large ventricular septal defect, malposed great arteries and left ventricular hypoplasia is discussed, highlighting the complexities involved in such a rare disorder. © 2014, Wiley Periodicals, Inc.

  6. [Electron microscope analysis of cardiomyocytes in the rat left ventricle under simulation of weightlessness effects and artificial gravitation].

    PubMed

    Varenik, E N; Lipina, T V; Shornikova, M V; Krasnov, I B; Chentsov, Iu S

    2012-01-01

    Electron microscopic study of left ventricle cardiomyocytes and quantitative analysis of their mitochondriom was performed in rats exposed to tail-suspension, as a model of weightlessness effects, to artificial gravity produced by intermittent 2G centrifugation and a combination of these effects. It was found that the cardiomyocytes ultrastructure changed slightly after tail-suspension and after intermittent 2G influence, as well as under a combination of these effects. However, the number of intermitochondrial junctions increased significantly in the interfibrillar zone of cardiomyocytes under a combination of tail-suspension and intermittent 2G influence, which agrees with the cell hypertrophy described earlier.

  7. Electrical approach to improve left ventricular activation during right ventricle stimulation.

    PubMed

    Bonomini, María Paula; Ortega, Daniel F; Barja, Luis D; Mangani, Nicolasa; Paolucci, Analía; Logarzo, Emilio

    2017-01-01

    Coronary sinus mapping is commonly used to evaluate left atrial activation. Herein, we propose to use it to assess which right ventricular pacing modality produces the shortest left ventricular activation times (R-LVtime) and the narrowest QRS widths. Three study groups were defined: 54 controls without intraventricular conduction disturbances; 15 patients with left bundle branch block, and other 15 with right bundle branch block. Left ventricular activation times and QRS widths were evaluated among groups under sinus rhythm, right ventricular apex, right ventricular outflow tract and high output septal zone (SEPHO). Left ventricular activation time was measured as the time elapsed from the surface QRS onset to the most distal left ventricular deflection recorded at coronary sinus. During the above stimulation modalities, coronary sinus mapping reproduced electrical differences that followed mechanical differences measured by tissue doppler imaging. Surprisingly, 33% of the patients with left bundle branch block displayed an early left ventricular activation time, suggesting that these patients would not benefit from resynchronization therapy. SEPHO improved QRS widths and left ventricular activation times in all groups, especially in patients with left bundle branch block, in whom these variables became similar to controls. Left ventricular activation time could be useful to search the optimum pacing site and would also enable detection of non-responders to cardiac resynchronization therapy. Finally, SEPHO resulted the best pacing modality, because it narrowed QRS-complexes and shortened left ventricular activations of patients with left bundle branch block and preserved the physiological depolarization of controls.

  8. Computational modeling of Takotsubo cardiomyopathy: effect of spatially varying β-adrenergic stimulation in the rat left ventricle

    PubMed Central

    Land, Sander; Niederer, Steven A.; Louch, William E.; Røe, Åsmund T.; Aronsen, Jan Magnus; Stuckey, Daniel J.; Sikkel, Markus B.; Tranter, Matthew H.; Lyon, Alexander R.; Harding, Sian E.

    2014-01-01

    In Takotsubo cardiomyopathy, the left ventricle shows apical ballooning combined with basal hypercontractility. Both clinical observations in humans and recent experimental work on isolated rat ventricular myocytes suggest the dominant mechanisms of this syndrome are related to acute catecholamine overload. However, relating observed differences in single cells to the capacity of such alterations to result in the extreme changes in ventricular shape seen in Takotsubo syndrome is difficult. By using a computational model of the rat left ventricle, we investigate which mechanisms can give rise to the typical shape of the ventricle observed in this syndrome. Three potential dominant mechanisms related to effects of β-adrenergic stimulation were considered: apical-basal variation of calcium transients due to differences in L-type and sarco(endo)plasmic reticulum Ca2+-ATPase activation, apical-basal variation of calcium sensitivity due to differences in troponin I phosphorylation, and apical-basal variation in maximal active tension due to, e.g., the negative inotropic effects of p38 MAPK. Furthermore, we investigated the interaction of these spatial variations in the presence of a failing Frank-Starling mechanism. We conclude that a large portion of the apex needs to be affected by severe changes in calcium regulation or contractile function to result in apical ballooning, and smooth linear variation from apex to base is unlikely to result in the typical ventricular shape observed in this syndrome. A failing Frank-Starling mechanism significantly increases apical ballooning at end systole and may be an important additional factor underpinning Takotsubo syndrome. PMID:25239804

  9. T3 enhances Ang2 in rat aorta in myocardial I/R: comparison with left ventricle.

    PubMed

    Sabatino, Laura; Kusmic, Claudia; Nicolini, Giuseppina; Amato, Rosario; Casini, Giovanni; Iervasi, Giorgio; Balzan, Silvana

    2016-10-01

    Angiogenesis is important for recovery after tissue damage in myocardial ischemia/reperfusion, and tri-iodothyronine (T3) has documented effects on angiogenesis. The angiopoietins 1/2 and tyrosine kinase receptor represent an essential system in angiogenesis controlling endothelial cell survival and vascular maturation. Recently, in a 3-day ischemia/reperfusion rat model, the infusion of a low dose of T3 improved the post-ischemic recovery of cardiac function.Adopting this model, our study aimed to investigate the effects of T3 on the capillary index and the expression of angiogenic genes as the angiopoietins 1/2 and tyrosine kinase receptor system, in the thoracic aorta and in the left ventricle. In the thoracic aorta, T3 infusion significantly improved the angiogenic sprouting and angiopoietin 2 expression. Instead, Sham-T3 group did not show any significant increment of capillary density and angiopoietin 2 expression. In the area at risk (AAR) of the left ventricle, T3 infusion did not increase capillary density but restored levels of angiopoietin 1, which were reduced in I/R group. Angiopoietin 2 levels were similar to Sham group and unchanged by T3 administration. In the remote zone, T3 induced a significant increment of both angiopoietin 1/2. In conclusion, T3 infusion induced a different response of angiopoietin 1/2 between the ventricle (the AAR and the remote zone) and the thoracic aorta, probably reflecting the different action of angiopoietin 1/2 in cardiomyocytes and endothelial cells. Overall, these data suggest a new aspect of T3-mediated cardioprotection through angiogenesis.

  10. Gender differences in normal left ventricle of adult FVB/N mice due to variation in interleukins and natriuretic peptides expression levels.

    PubMed

    Haroon, Javeria; Foureaux, Giselle; Martins, Almir S; Ferreira, Anderson J; Reis, Adelina M; Javed, Qamar

    2015-01-01

    This study examined the sex differences for physical, morphological, histological, mRNA, and protein expression levels changes for interleukins and natriuretic peptides in left ventricle (LV) of two groups of adult FVB/N mice; males (WM) and females (WF). LV morphological, histological, reverse transcription and quantitative real-time PCR (RT-PCR), and immunohistochemical (IHC) alterations were determined in FVB/N mice at 34-35 weeks on gender basis. Confirming the gender dimorphism, FVB/N males (WM) illustrated a significant reduction in ANP and IL1-A levels as well as significantly increased body weight (BW (gm)), tibia length (TL (mm)), heart weight (HW (mg)), heart weight-to-body weight (HW/BW (mg/gm)) ratio, heart weight-to-tibia length (HW/TL (mg/mm)) ratio, left ventricle weight (LV (mg)), left ventricle-to-body weight (LV/BW (mg/gm)) ratio, and left ventricle-to-tibia length (LV/TL (mg/mm)) ratio, left ventricular (LV) cardiomyocyte diameter, high BNP, NPRA, IL-1B, and IL1R1 expression in comparison with FVB/N females (WF). Gender differences in relation to left ventricle (LV) may be due to differences in the interleukins and natriuretic peptides levels as an outcome of sex related hormones. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. A case of SAPIEN XT valve fallen into left ventricle during valve-in-valve transcatheter aortic valve implantation.

    PubMed

    Koizumi, Shigeki; Ehara, Natsuhiko; Nishiya, Kenta; Koyama, Tadaaki

    2017-06-24

    Late transcatheter heart valve embolization is a rare but life-threatening complication of transcatheter aortic valve implantation. Surgical intervention is performed for most cases, but some cases were treated by valve-in-valve transcatheter aortic valve implantation. We describe a patient in whom a 29-mm Edwards SAPIEN XT valve migrated into the left ventricular outflow tract 41 days after the initial implantation. We tried to perform valve-in-valve transcatheter aortic valve implantation using a transfemoral approach. As soon as the second transcatheter heart valve touched the first implanted valve, it fell into the left ventricle. Immediate surgical intervention was required. The first valve was removed, and surgical aortic valve replacement was successfully performed. In conclusion, we should choose surgical aortic valve replacement for late transcatheter heart valve embolization. Even if we need to treat by catheter intervention, transapical approach may be better.

  12. Simplified [18F]FDG Image-Derived Input Function Using the Left Ventricle, Liver, and One Venous Blood Sample

    PubMed Central

    Tantawy, Mohammed Noor; Peterson, Todd E.

    2014-01-01

    A relatively simple, almost entirely noninvasive imaging-based method is presented for deriving arterial blood input functions for quantitative [18F]2-fluoro-2-deoxy-D-glucose (FDG) positron emission tomographic (PET) studies in rodents. It requires only one venous blood sample at the end of the scan. MicroPET images and arterial blood time-activity curves (TACs) were downloaded from the Mouse Quantitation Program database at the University of California, Los Angeles. Three-dimensional regions of interest were drawn around the blood-pool region of the left ventricle and within the liver to derive their respective TACs. To construct the “hybrid” image-derived input function (IDIF), the initial part of the left ventricle TAC, containing the peak concentration of [18F]FDG in the arterial blood, was corrected for spillout (ie, partial-volume effect yielding a recovery coefficient < 1) and then joined to the liver TAC (normalized to the 60-minute arterial blood sample) immediately after it peaks. To validate our method, the [18F]FDG influx constant (Ki) was estimated using a two-tissue compartment model and compared to estimates of Ki obtained using measured arterial blood TACs. No significant difference in the Ki estimates was obtained with the arterial blood input function and our hybrid IDIF. We conclude that the normalized hybrid IDIF can be used in practice to obtain reliable Ki estimates. PMID:20236605

  13. Simultaneous pressure-volume measurements using optical sensors and MRI for left ventricle function assessment during animal experiment.

    PubMed

    Abi-Abdallah Rodriguez, Dima; Durand, Emmanuel; de Rochefort, Ludovic; Boudjemline, Younes; Mousseaux, Elie

    2015-01-01

    Simultaneous pressure and volume measurements enable the extraction of valuable parameters for left ventricle function assessment. Cardiac MR has proven to be the most accurate method for volume estimation. Nonetheless, measuring pressure simultaneously during MRI acquisitions remains a challenge given the magnetic nature of the widely used pressure transducers. In this study we show the feasibility of simultaneous in vivo pressure-volume acquisitions with MRI using optical pressure sensors. Pressure-volume loops were calculated while inducing three inotropic states in a sheep and functional indices were extracted, using single beat loops, to characterize systolic and diastolic performance. Functional indices evolved as expected in response to positive inotropic stimuli. The end-systolic elastance, representing the contractility index, the diastolic myocardium compliance, and the cardiac work efficiency all increased when inducing inotropic state enhancement. The association of MRI and optical pressure sensors within the left ventricle successfully enabled pressure-volume loop analysis after having respective data simultaneously recorded during the experimentation without the need to move the animal between each inotropic state. Copyright © 2014 IPEM. Published by Elsevier Ltd. All rights reserved.

  14. Effect of the architecture of the left ventricle on the speed of the excitation wave in muscle fibers

    NASA Astrophysics Data System (ADS)

    Nezlobinsky, T. V.; Pravdin, S. F.; Katsnelson, L. B.; Solovyova, O. E.

    2016-07-01

    It is known that preferential paths for the propagation of an electrical excitation wave in the human ventricular myocardium are associated with muscle fibers in tissue. The speed of the excitation wave along a fiber is several times higher than that across the direction of the fiber. To estimate the effect of the architecture and anisotropy of the myocardium of the left ventricle on the process of its electrical activation, we have studied the relation between the speed of the electrical excitation wave in a one-dimensional isolated myocardial fiber consisting of sequentially coupled cardiomyocytes and in an identical fiber located in the wall of a threedimensional anatomical model of the left ventricle. It has been shown that the speed of a wavefront along the fiber in the three-dimensional myocardial tissue is much higher than that in the one-dimensional fiber. The acceleration of the signal is due to the rotation of directions of fibers in the wall and to the position of the excitation wavefront with respect to the direction of this fiber. The observed phenomenon is caused by the approach of the excitable tissue with rotational anisotropy in its properties to a pseudoisotropic tissue.

  15. [Molecular mechanism by which green tea and tea extract inhibits left ventricle hypertrophy induced by renovascular hypertension in rats].

    PubMed

    Mao, Weifeng; Song, Yan; Han, Chi; Li, Ning

    2008-01-01

    To investigate the preventive effects and the molecular mechanism of tea and tea extracts (polyphenols and EGCG) on left ventricle hypertrophy (LVH) induced by Renovascular hypertension in rats. One hundred and sixty male Wistar rats were randomly divided into five groups: negative control group (SHAM), operation group (2K1C), green tea group (2K1C + GT), tea polyphenol group (2K1C + TP), EGCG group (2K1C + EGCG). After surgery operation, rats in different groups received tap water, tap water, 2% green tea, 0.1% tea polyphenol and 0.05% EGCG respectively, as the sole drinking source for 8 weeks until the end of the experiment. The results showed that the blood pressure, the ratio of left ventricle weight to body weight (LVW/BW) and the left ventricular wall thicknesses (LVWT) in 2K1C group significantly increased (P < 0.01), when compared to those in sham operation group. However, when compared to these parameters in operation group, the ratio of LVW/BW and HW/BW in green tea group, tea polyphenols group and EGCG group significantly decreased (P < 0.05), while the activities of GSH-Px and SOD increased, and the levels of ROS in heart were also significantly decreased (P < 0.05). Ras, P-ERK protein expressions in tea-treatment groups were also decreased. Green tea, tea polyphenols and EGCG can attenuate the development of left ventricular hypertrophy induced by renal hypertension in rats. The possible mechanisms may be due to its antioxidant properties and the modulation of Ras-to-MAPKs mediated signal transduction.

  16. Visualization of higher order finite elements.

    SciTech Connect

    Thompson, David C.; Pebay, Philippe Pierre; Crawford, Richard H.; Khardekar, Rahul Vinay

    2004-04-01

    Finite element meshes are used to approximate the solution to some differential equation when no exact solution exists. A finite element mesh consists of many small (but finite, not infinitesimal or differential) regions of space that partition the problem domain, {Omega}. Each region, or element, or cell has an associated polynomial map, {Phi}, that converts the coordinates of any point, x = ( x y z ), in the element into another value, f(x), that is an approximate solution to the differential equation, as in Figure 1(a). This representation works quite well for axis-aligned regions of space, but when there are curved boundaries on the problem domain, {Omega}, it becomes algorithmically much more difficult to define {Phi} in terms of x. Rather, we define an archetypal element in a new coordinate space, r = ( r s t ), which has a simple, axis-aligned boundary (see Figure 1(b)) and place two maps onto our archetypal element:

  17. Finite element modelling of SAW correlator

    NASA Astrophysics Data System (ADS)

    Tikka, Ajay C.; Al-Sarawi, Said F.; Abbott, Derek

    2007-12-01

    Numerical simulations of SAW correlators so far are limited to delta function and equivalent circuit models. These models are not accurate as they do not replicate the actual behaviour of the device. Manufacturing a correlator to specifically realise a different configuration is both expensive and time consuming. With the continuous improvement in computing capacity, switching to finite element modelling would be more appropriate. In this paper a novel way of modelling a SAW correlator using finite element analysis is presented. This modelling approach allows the consideration of different code implementation and device structures. This is demonstrated through simulation results for a 5×2-bit Barker sequence encoded SAW correlator. These results show the effect of both bulk and leaky modes on the device performance at various operating frequencies. Moreover, the ways in which the gain of the correlator can be optimised though variation of design parameters will also be outlined.

  18. Finite element wavelets with improved quantitative properties

    NASA Astrophysics Data System (ADS)

    Nguyen, Hoang; Stevenson, Rob

    2009-08-01

    In [W. Dahmen, R. Stevenson, Element-by-element construction of wavelets satisfying stability and moment conditions, SIAM J. Numer. Anal. 37 (1) (1999) 319-352 (electronic)], finite element wavelets were constructed on polygonal domains or Lipschitz manifolds that are piecewise parametrized by mappings with constant Jacobian determinants. The wavelets could be arranged to have any desired order of cancellation properties, and they generated stable bases for the Sobolev spaces Hs for (or s<=1 on manifolds). Unfortunately, it appears that the quantitative properties of these wavelets are rather disappointing. In this paper, we modify the construction from the above-mentioned work to obtain finite element wavelets which are much better conditioned.

  19. EC Vacuum Vessel Finite Element Analysis

    SciTech Connect

    Rudland, D.; Luther, R.; /Fermilab

    1992-02-04

    This Note contains a summary of the results of the finite element analysis of the EC Cryostat vacuum vessel performed by Dave Rudland in 1987. The results are used in the structural evaluation of the EC cryostats presented in Engineering Note 194. It should also be noted that the adequacy of the design of the vacuum vessels was reviewed and verified by the Battelle Memorial Institute. Battelle used a shell of revolution program to essentially duplicate the FEA analysis with similar results. It should be noted that no plots of the finite element mesh were retained from the analysis, and these can not be easily reproduced due to a change in the version of the ANSYS computer program shortly after the analysis was completed.

  20. Finite element substructuring methods for composite mechanics

    NASA Technical Reports Server (NTRS)

    Murthy, Pappu L. N.; Chamis, Christos C.

    1988-01-01

    Finite element substructuring strategies are presented to obtain numerical solutions for three typical problems of interest to the composites community: (1) impact and toughness characterization of composites using Charpy's impact test specimen; (2) free-edge stress analysis of composite laminates; and (3) fracture toughness predictions of composites for individual and combined fracture of modes I, II, and III. The key issue common to these problems is the presence of singular or near singular stress fields. The regions prone to see steep stress gradients are substructured with progressively refined meshes to study the local response simultaneously with the global response. The results from the select examples indicate that finite element substructuring methods are computationally effective for composite singularity mechanics.

  1. Revolution in Orthodontics: Finite element analysis

    PubMed Central

    Singh, Johar Rajvinder; Kambalyal, Prabhuraj; Jain, Megha; Khandelwal, Piyush

    2016-01-01

    Engineering has not only developed in the field of medicine but has also become quite established in the field of dentistry, especially Orthodontics. Finite element analysis (FEA) is a computational procedure to calculate the stress in an element, which performs a model solution. This structural analysis allows the determination of stress resulting from external force, pressure, thermal change, and other factors. This method is extremely useful for indicating mechanical aspects of biomaterials and human tissues that can hardly be measured in vivo. The results obtained can then be studied using visualization software within the finite element method (FEM) to view a variety of parameters, and to fully identify implications of the analysis. This is a review to show the applications of FEM in Orthodontics. It is extremely important to verify what the purpose of the study is in order to correctly apply FEM. PMID:27114948

  2. Finite element modeling of permanent magnet devices

    NASA Astrophysics Data System (ADS)

    Brauer, J. R.; Larkin, L. A.; Overbye, V. D.

    1984-03-01

    New techniques are presented for finite element modeling of permanent magnets in magnetic devices such as motors and generators. These techniques extend a previous sheet-current permanent magnet model that applies only for straight line B-H loops and rectangular-shaped magnets. Here Maxwell's equations are used to derive the model of a permanent magnet having a general curved B-H loop and any geometric shape. The model enables a nonlinear magnetic finite element program to use Newton-Raphson iteration to solve for saturable magnetic fields in a wide variety of devices containing permanent magnets and steels. The techniques are applied to a brushless dc motor with irregular-shaped permanent magnets. The calculated motor torque agrees well with measured torque.

  3. Finite element analysis of human joints

    SciTech Connect

    Bossart, P.L.; Hollerbach, K.

    1996-09-01

    Our work focuses on the development of finite element models (FEMs) that describe the biomechanics of human joints. Finite element modeling is becoming a standard tool in industrial applications. In highly complex problems such as those found in biomechanics research, however, the full potential of FEMs is just beginning to be explored, due to the absence of precise, high resolution medical data and the difficulties encountered in converting these enormous datasets into a form that is usable in FEMs. With increasing computing speed and memory available, it is now feasible to address these challenges. We address the first by acquiring data with a high resolution C-ray CT scanner and the latter by developing semi-automated method for generating the volumetric meshes used in the FEM. Issues related to tomographic reconstruction, volume segmentation, the use of extracted surfaces to generate volumetric hexahedral meshes, and applications of the FEM are described.

  4. Finite element concepts in computational aerodynamics

    NASA Technical Reports Server (NTRS)

    Baker, A. J.

    1978-01-01

    Finite element theory was employed to establish an implicit numerical solution algorithm for the time averaged unsteady Navier-Stokes equations. Both the multidimensional and a time-split form of the algorithm were considered, the latter of particular interest for problem specification on a regular mesh. A Newton matrix iteration procedure is outlined for solving the resultant nonlinear algebraic equation systems. Multidimensional discretization procedures are discussed with emphasis on automated generation of specific nonuniform solution grids and accounting of curved surfaces. The time-split algorithm was evaluated with regards to accuracy and convergence properties for hyperbolic equations on rectangular coordinates. An overall assessment of the viability of the finite element concept for computational aerodynamics is made.

  5. Exact finite elements for conduction and convection

    NASA Technical Reports Server (NTRS)

    Thornton, E. A.; Dechaumphai, P.; Tamma, K. K.

    1981-01-01

    An appproach for developing exact one dimensional conduction-convection finite elements is presented. Exact interpolation functions are derived based on solutions to the governing differential equations by employing a nodeless parameter. Exact interpolation functions are presented for combined heat transfer in several solids of different shapes, and for combined heat transfer in a flow passage. Numerical results demonstrate that exact one dimensional elements offer advantages over elements based on approximate interpolation functions. Previously announced in STAR as N81-31507

  6. Finite element analysis of wrinkling membranes

    NASA Technical Reports Server (NTRS)

    Miller, R. K.; Hedgepeth, J. M.; Weingarten, V. I.; Das, P.; Kahyai, S.

    1984-01-01

    The development of a nonlinear numerical algorithm for the analysis of stresses and displacements in partly wrinkled flat membranes, and its implementation on the SAP VII finite-element code are described. A comparison of numerical results with exact solutions of two benchmark problems reveals excellent agreement, with good convergence of the required iterative procedure. An exact solution of a problem involving axisymmetric deformations of a partly wrinkled shallow curved membrane is also reported.

  7. A multidimensional finite element method for CFD

    NASA Technical Reports Server (NTRS)

    Pepper, Darrell W.; Humphrey, Joseph W.

    1991-01-01

    A finite element method is used to solve the equations of motion for 2- and 3-D fluid flow. The time-dependent equations are solved explicitly using quadrilateral (2-D) and hexahedral (3-D) elements, mass lumping, and reduced integration. A Petrov-Galerkin technique is applied to the advection terms. The method requires a minimum of computational storage, executes quickly, and is scalable for execution on computer systems ranging from PCs to supercomputers.

  8. Exact finite elements for conduction and convection

    NASA Technical Reports Server (NTRS)

    Thornton, E. A.; Dechaumphai, P.; Tamma, K. K.

    1981-01-01

    An appproach for developing exact one dimensional conduction-convection finite elements is presented. Exact interpolation functions are derived based on solutions to the governing differential equations by employing a nodeless parameter. Exact interpolation functions are presented for combined heat transfer in several solids of different shapes, and for combined heat transfer in a flow passage. Numerical results demonstrate that exact one dimensional elements offer advantages over elements based on approximate interpolation functions. Previously announced in STAR as N81-31507

  9. Quadrilateral/hexahedral finite element mesh coarsening

    DOEpatents

    Staten, Matthew L; Dewey, Mark W; Scott, Michael A; Benzley, Steven E

    2012-10-16

    A technique for coarsening a finite element mesh ("FEM") is described. This technique includes identifying a coarsening region within the FEM to be coarsened. Perimeter chords running along perimeter boundaries of the coarsening region are identified. The perimeter chords are redirected to create an adaptive chord separating the coarsening region from a remainder of the FEM. The adaptive chord runs through mesh elements residing along the perimeter boundaries of the coarsening region. The adaptive chord is then extracted to coarsen the FEM.

  10. Finite element methods in fracture mechanics

    NASA Technical Reports Server (NTRS)

    Liebowitz, H.; Moyer, E. T., Jr.

    1989-01-01

    Finite-element methodology specific to the analysis of fracture mechanics problems is reviewed. Primary emphasis is on the important algorithmic developments which have enhanced the numerical modeling of fracture processes. Methodologies to address elastostatic problems in two and three dimensions, elastodynamic problems, elastoplastic problems, special considerations for three-dimensional nonlinear problems, and the modeling of stable crack growth are reviewed. In addition, the future needs of the fracture community are discussed and open questions are identified.

  11. Finite element analysis of flexible, rotating blades

    NASA Technical Reports Server (NTRS)

    Mcgee, Oliver G.

    1987-01-01

    A reference guide that can be used when using the finite element method to approximate the static and dynamic behavior of flexible, rotating blades is given. Important parameters such as twist, sweep, camber, co-planar shell elements, centrifugal loads, and inertia properties are studied. Comparisons are made between NASTRAN elements through published benchmark tests. The main purpose is to summarize blade modeling strategies and to document capabilities and limitations (for flexible, rotating blades) of various NASTRAN elements.

  12. Finite Element Output Bounds for Hyperbolic Problems

    SciTech Connect

    Machiels, L.

    2000-03-27

    We propose a Neumann-subproblem a posteriori finite element error bound technique for linear stationary scalar advection problems. The method is similar in many respects to the previous output bound technique developed for elliptic problems. In the new approach, however, the primal residual is enhanced with a streamline diffusion term. We first formulate the bound algorithm, with particular emphasis on the proof of the bounding properties; then, we provide numerical results for an illustrative example.

  13. Adaptive finite element strategies for shell structures

    NASA Technical Reports Server (NTRS)

    Stanley, G.; Levit, I.; Stehlin, B.; Hurlbut, B.

    1992-01-01

    The present paper extends existing finite element adaptive refinement (AR) techniques to shell structures, which have heretofore been neglected in the AR literature. Specific challenges in applying AR to shell structures include: (1) physical discontinuities (e.g., stiffener intersections); (2) boundary layers; (3) sensitivity to geometric imperfections; (4) the sensitivity of most shell elements to mesh distortion, constraint definition and/or thinness; and (5) intrinsic geometric nonlinearity. All of these challenges but (5) are addressed here.

  14. Finite Element Methods: Principles for Their Selection.

    DTIC Science & Technology

    1983-02-01

    the finite element methods. 39 Various statements in the literature that certain mixed methods work well inspite of the fact that the LBB (BB...method, displacement and mixed methods , various adaptive approaches, etc. The examples discussed in Sections 2 and 3 show that the same computational...performance and their relation to mixed methods , SIAM J. Num. Anal., to appear. 5. F. Brezzi, On the existence uniqueness and approximation of saddle-point

  15. EXODUS II: A finite element data model

    SciTech Connect

    Schoof, L.A.; Yarberry, V.R.

    1994-09-01

    EXODUS II is a model developed to store and retrieve data for finite element analyses. It is used for preprocessing (problem definition), postprocessing (results visualization), as well as code to code data transfer. An EXODUS II data file is a random access, machine independent, binary file that is written and read via C, C++, or Fortran library routines which comprise the Application Programming Interface (API).

  16. Finite Element Analysis of Reverberation Chambers

    NASA Technical Reports Server (NTRS)

    Bunting, Charles F.; Nguyen, Duc T.

    2000-01-01

    The primary motivating factor behind the initiation of this work was to provide a deterministic means of establishing the validity of the statistical methods that are recommended for the determination of fields that interact in -an avionics system. The application of finite element analysis to reverberation chambers is the initial step required to establish a reasonable course of inquiry in this particularly data-intensive study. The use of computational electromagnetics provides a high degree of control of the "experimental" parameters that can be utilized in a simulation of reverberating structures. As the work evolved there were four primary focus areas they are: 1. The eigenvalue problem for the source free problem. 2. The development of a complex efficient eigensolver. 3. The application of a source for the TE and TM fields for statistical characterization. 4. The examination of shielding effectiveness in a reverberating environment. One early purpose of this work was to establish the utility of finite element techniques in the development of an extended low frequency statistical model for reverberation phenomena. By employing finite element techniques, structures of arbitrary complexity can be analyzed due to the use of triangular shape functions in the spatial discretization. The effects of both frequency stirring and mechanical stirring are presented. It is suggested that for the low frequency operation the typical tuner size is inadequate to provide a sufficiently random field and that frequency stirring should be used. The results of the finite element analysis of the reverberation chamber illustrate io-W the potential utility of a 2D representation for enhancing the basic statistical characteristics of the chamber when operating in a low frequency regime. The basic field statistics are verified for frequency stirring over a wide range of frequencies. Mechanical stirring is shown to provide an effective frequency deviation.

  17. Finite element based electric motor design optimization

    NASA Technical Reports Server (NTRS)

    Campbell, C. Warren

    1993-01-01

    The purpose of this effort was to develop a finite element code for the analysis and design of permanent magnet electric motors. These motors would drive electromechanical actuators in advanced rocket engines. The actuators would control fuel valves and thrust vector control systems. Refurbishing the hydraulic systems of the Space Shuttle after each flight is costly and time consuming. Electromechanical actuators could replace hydraulics, improve system reliability, and reduce down time.

  18. Finite Element Results Visualization for Unstructured Grids

    SciTech Connect

    Speck, Douglas E.; Dovey, Donald J.

    1996-07-15

    GRIZ is a general-purpose post-processing application supporting interactive visualization of finite element analysis results on unstructured grids. In addition to basic pseudocolor renderings of state variables over the mesh surface, GRIZ provides modern visualization techniques such as isocontours and isosurfaces, cutting planes, vector field display, and particle traces. GRIZ accepts both command-line and mouse-driven input, and is portable to virtually any UNIX platform which provides Motif and OpenGl libraries.

  19. Exact finite elements for conduction and convection

    NASA Technical Reports Server (NTRS)

    Thornton, E. A.; Dechaumphai, P.; Tamma, K. K.

    1981-01-01

    An approach for developing exact one dimensional conduction-convection finite elements is presented. Exact interpolation functions are derived based on solutions to the governing differential equations by employing a nodeless parameter. Exact interpolation functions are presented for combined heat transfer in several solids of different shapes, and for combined heat transfer in a flow passage. Numerical results demonstrate that exact one dimensional elements offer advantages over elements based on approximate interpolation functions.

  20. Finite element modeling of nonisothermal polymer flows

    NASA Technical Reports Server (NTRS)

    Roylance, D.

    1981-01-01

    A finite element formulation designed to simulate polymer melt flows in which both conductive and convective heat transfer are important is described, and the numerical model is illustrated by means of computer experiments using extruder drag flow and entry flow as trial problems. Fluid incompressibility is enforced by a penalty treatment of the element pressures, and the thermal convective transport is modeled by conventional Galerkin and optimal upwind treatments.

  1. Variational approach to probabilistic finite elements

    NASA Technical Reports Server (NTRS)

    Belytschko, T.; Liu, W. K.; Mani, A.; Besterfield, G.

    1991-01-01

    Probabilistic finite element methods (PFEM), synthesizing the power of finite element methods with second-moment techniques, are formulated for various classes of problems in structural and solid mechanics. Time-invariant random materials, geometric properties and loads are incorporated in terms of their fundamental statistics viz. second-moments. Analogous to the discretization of the displacement field in finite element methods, the random fields are also discretized. Preserving the conceptual simplicity, the response moments are calculated with minimal computations. By incorporating certain computational techniques, these methods are shown to be capable of handling large systems with many sources of uncertainties. By construction, these methods are applicable when the scale of randomness is not very large and when the probabilistic density functions have decaying tails. The accuracy and efficiency of these methods, along with their limitations, are demonstrated by various applications. Results obtained are compared with those of Monte Carlo simulation and it is shown that good accuracy can be obtained for both linear and nonlinear problems. The methods are amenable to implementation in deterministic FEM based computer codes.

  2. Variational approach to probabilistic finite elements

    NASA Technical Reports Server (NTRS)

    Belytschko, T.; Liu, W. K.; Mani, A.; Besterfield, G.

    1987-01-01

    Probabilistic finite element method (PFEM), synthesizing the power of finite element methods with second-moment techniques, are formulated for various classes of problems in structural and solid mechanics. Time-invariant random materials, geometric properties, and loads are incorporated in terms of their fundamental statistics viz. second-moments. Analogous to the discretization of the displacement field in finite element methods, the random fields are also discretized. Preserving the conceptual simplicity, the response moments are calculated with minimal computations. By incorporating certain computational techniques, these methods are shown to be capable of handling large systems with many sources of uncertainties. By construction, these methods are applicable when the scale of randomness is not very large and when the probabilistic density functions have decaying tails. The accuracy and efficiency of these methods, along with their limitations, are demonstrated by various applications. Results obtained are compared with those of Monte Carlo simulation and it is shown that good accuracy can be obtained for both linear and nonlinear problems. The methods are amenable to implementation in deterministic FEM based computer codes.

  3. Finite element modeling of lipid bilayer membranes

    NASA Astrophysics Data System (ADS)

    Feng, Feng; Klug, William S.

    2006-12-01

    A numerical simulation framework is presented for the study of biological membranes composed of lipid bilayers based on the finite element method. The classic model for these membranes employs a two-dimensional-fluid-like elastic constitutive law which is sensitive to curvature, and subjects vesicles to physically imposed constraints on surface area and volume. This model is implemented numerically via the use of C1-conforming triangular Loop subdivision finite elements. The validity of the framework is tested by computing equilibrium shapes from previously-determined axisymmetric shape-phase diagram of lipid bilayer vesicles with homogeneous material properties. Some of the benefits and challenges of finite element modeling of lipid bilayer systems are discussed, and it is indicated how this framework is natural for future investigation of biologically realistic bilayer structures involving nonaxisymmetric geometries, binding and adhesive interactions, heterogeneous mechanical properties, cytoskeletal interactions, and complex loading arrangements. These biologically relevant features have important consequences for the shape mechanics of nonidealized vesicles and cells, and their study requires not simply advances in theory, but also advances in numerical simulation techniques, such as those presented here.

  4. Gauge finite element method for incompressible flows

    NASA Astrophysics Data System (ADS)

    E, Weinan; Liu, Jian-Guo

    2000-12-01

    A finite element method for computing viscous incompressible flows based on the gauge formulation introduced in [Weinan E, Liu J-G. Gauge method for viscous incompressible flows. Journal of Computational Physics (submitted)] is presented. This formulation replaces the pressure by a gauge variable. This new gauge variable is a numerical tool and differs from the standard gauge variable that arises from decomposing a compressible velocity field. It has the advantage that an additional boundary condition can be assigned to the gauge variable, thus eliminating the issue of a pressure boundary condition associated with the original primitive variable formulation. The computational task is then reduced to solving standard heat and Poisson equations, which are approximated by straightforward, piecewise linear (or higher-order) finite elements. This method can achieve high-order accuracy at a cost comparable with that of solving standard heat and Poisson equations. It is naturally adapted to complex geometry and it is much simpler than traditional finite element methods for incompressible flows. Several numerical examples on both structured and unstructured grids are presented. Copyright

  5. FESDIF -- Finite Element Scalar Diffraction theory code

    SciTech Connect

    Kraus, H.G.

    1992-09-01

    This document describes the theory and use of a powerful scalar diffraction theory based computer code for calculation of intensity fields due to diffraction of optical waves by two-dimensional planar apertures and lenses. This code is called FESDIF (Finite Element Scalar Diffraction). It is based upon both Fraunhofer and Kirchhoff scalar diffraction theories. Simplified routines for circular apertures are included. However, the real power of the code comes from its basis in finite element methods. These methods allow the diffracting aperture to be virtually any geometric shape, including the various secondary aperture obstructions present in telescope systems. Aperture functions, with virtually any phase and amplitude variations, are allowed in the aperture openings. Step change aperture functions are accommodated. The incident waves are considered to be monochromatic. Plane waves, spherical waves, or Gaussian laser beams may be incident upon the apertures. Both area and line integral transformations were developed for the finite element based diffraction transformations. There is some loss of aperture function generality in the line integral transformations which are typically many times more computationally efficient than the area integral transformations when applicable to a particular problem.

  6. Stabilized Finite Elements in FUN3D

    NASA Technical Reports Server (NTRS)

    Anderson, W. Kyle; Newman, James C.; Karman, Steve L.

    2017-01-01

    A Streamlined Upwind Petrov-Galerkin (SUPG) stabilized finite-element discretization has been implemented as a library into the FUN3D unstructured-grid flow solver. Motivation for the selection of this methodology is given, details of the implementation are provided, and the discretization for the interior scheme is verified for linear and quadratic elements by using the method of manufactured solutions. A methodology is also described for capturing shocks, and simulation results are compared to the finite-volume formulation that is currently the primary method employed for routine engineering applications. The finite-element methodology is demonstrated to be more accurate than the finite-volume technology, particularly on tetrahedral meshes where the solutions obtained using the finite-volume scheme can suffer from adverse effects caused by bias in the grid. Although no effort has been made to date to optimize computational efficiency, the finite-element scheme is competitive with the finite-volume scheme in terms of computer time to reach convergence.

  7. Finite element simulations of stacked crystal filters

    NASA Astrophysics Data System (ADS)

    Lee, Jiunn-Horng; Tzeng, Kung-Yu; Cheng, Chih-Wei; Shih, Yu-Ching; Yao, Chih-Min

    2004-03-01

    Wireless networks are growing rapidly. Their applications include cellular phone, satellite communication and wireless local area networks. In order to avoid interference between all these applications, high selectivity RF filters are essential. The stacked crystal filter (SCF) is a useful configuration when low insertion loss is desired and the near-in skirt selectivity requirement is not as high as that produced by ladder filters. A SCF is an acoustically coupled resonator filter which includes a pair of thickness mode piezoelectric plates attached to each other. Mounted between adjacent sides of the two plates is a shared electrode. The common ways to model the SCF are mason model and lumped element equivalent circuit method. To accommodate complicated geometries, we need to use the other kinds of numerical analysis techniques. Finite element methods have been applied to the modeling of thin film bulk acoustic wave resonator in recent years. Advanced FEM software has the capability to do a coupled piezoelectric-circuit analysis that can connect electrical circuits directly to the piezoelectric finite element models. In this work, we integrate the SCF two-dimensional piezoelectric finite element models and electrical circuits together to simulate the performance of SCF. The influences of electrode property and acoustic loss to the performance of filter are also investigated. The results of simulation are verified by mason model. This methodology can be applied to more complicated geometry models and other types of filters simulation such as coupled resonator filters (CRF) and ladder filters.

  8. [Echocardiographic characteristics of the left heart ventricle in people with different somatotypes].

    PubMed

    Seebaluck, Sh; Babaev, M V; Kondrashev, A V

    2003-01-01

    The objective of this study was to analyze echocardiographic parameters in 143 healthy individuals aged 18-21 years with different somatotypes. The evaluation of somatotype was performed using the the method of R.N. Dorokhov and V.G. Petrukhin (1989). During the echocardiography, left ventricular wall thickness, internal diameter and myocardial mass were measured. The investigation showed marked sex- and somatotype-related differences in left ventricular parameters. The correlations between the studied left ventricular parameters and body mass, length and surface area were demonstrated. The optimal method of the indexation of left ventricular myocardial mass as related to (body length)3, is described.

  9. Wave dispersion properties of compound finite elements

    NASA Astrophysics Data System (ADS)

    Melvin, Thomas; Thuburn, John

    2017-06-01

    Mixed finite elements use different approximation spaces for different dependent variables. Certain classes of mixed finite elements, called compatible finite elements, have been shown to exhibit a number of desirable properties for a numerical weather prediction model. In two-dimensions the lowest order element of the Raviart-Thomas based mixed element is the finite element equivalent of the widely used C-grid staggering, which is known to possess good wave dispersion properties, at least for quadrilateral grids. It has recently been proposed that building compound elements from a number of triangular Raviart-Thomas sub-elements, such that both the primal and (implied) dual grid are constructed from the same sub-elements, would allow greater flexibility in the use of different advection schemes along with the ability to build arbitrary polygonal elements. Although the wave dispersion properties of the triangular sub-elements are well understood, those of the compound elements are unknown. It would be useful to know how they compare with the non-compound elements and what properties of the triangular sub-grid elements are inherited? Here a numerical dispersion analysis is presented for the linear shallow water equations in two dimensions discretised using the lowest order compound Raviart-Thomas finite elements on regular quadrilateral and hexagonal grids. It is found that, in comparison with the well known C-grid scheme, the compound elements exhibit a more isotropic dispersion relation, with a small over estimation of the frequency for short waves compared with the relatively large underestimation for the C-grid. On a quadrilateral grid the compound elements are found to differ from the non-compound Raviart-Thomas quadrilateral elements even for uniform elements, exhibiting the influence of the underlying sub-elements. This is shown to lead to small improvements in the accuracy of the dispersion relation: the compound quadrilateral element is slightly better for

  10. Parametric ultrasound and fluoroscopy image fusion for guidance of left ventricle lead placement in cardiac resynchronization therapy

    PubMed Central

    Babic, Aleksandar; Odland, Hans Henrik; Gérard, Olivier; Samset, Eigil

    2015-01-01

    Abstract. Recent studies show that the response rate to cardiac resynchronization therapy (CRT) could be improved if the left ventricle (LV) is paced at the site of the latest mechanical activation, but away from the myocardial scar. A prototype system for CRT lead placement guidance that combines LV functional information from ultrasound with live x-ray fluoroscopy was developed. Two mean anatomical models, each containing LV epi-, LV endo- and right ventricle endocardial surfaces, were computed from a database of 33 heart failure patients as a substitute for a patient-specific model. The sphericity index was used to divide the observed population into two groups. The distance between the mean and the patient-specific models was determined using a signed distance field metric (reported in mm). The average error values for LV epicardium were −0.4±4.6 and for LV endocardium were −0.3±4.4. The validity of using average LV models for a CRT procedure was tested by simulating coronary vein selection in a group of 15 CRT candidates. The probability of selecting the same coronary branch, when basing the selection on the average model compared to a patient-specific model, was estimated to be 95.3±2.9%. This was found to be clinically acceptable. PMID:26158110

  11. Influence of the heart rate and atrioventricular delays on vortex evolution and blood transport inside the left ventricle

    NASA Astrophysics Data System (ADS)

    Hendabadi, Sahar; Martinez-Legazpi, Pablo; Benito, Yolanda; Bermejo, Javier; Del Alamo, Juan Carlos; Shadden, Shawn

    2013-11-01

    Cardiac resynchronization therapy (CRT) is used to help restore coordinated pumping of the ventricles by overcoming delays in electrical conduction due to cardiac disease. This is accomplished by a specialized cardiac pacemaker that is able to adjust the atrioventricular (AV) delay.A major clinical challenge is to adjust the pacing strategy to best coordinate the blood flow mechanics of ventricular filling and ejection. To this end, we have studied the difference in the vortex formation and its evolution inside the left ventricle (LV) for 4 different AV delays in a cohort of patients with implanted pacemakers. A reconstruction algorithm was used to obtain 2D velocity over the apical long-axis view of the LV from color Doppler and B-mode ultrasound data. To study blood transport, we have identified Lagrangian coherent structures to determine moving boundaries of the blood volumes injected to the LV in diastole and ejected to the aorta in systole. In all cases, we have analyzed the differences in filling and ejection patterns and the blood transport during the E-wave and A-wave formation.Finally we have assessed the influence of the AV delay on 2 indices of stasis, direct flow and residence time.The findings shed insight to the optimization of AV delays in patients undergoing CRT. NIH award 5R21HL108268 and grants PIS09/02603 and RD06/0010 from the Plan Nacional de Investigacion Cientifica, Spain.

  12. MRI-based CFD analysis of flow in a human left ventricle: methodology and application to a healthy heart.

    PubMed

    Schenkel, Torsten; Malve, Mauro; Reik, Michael; Markl, Michael; Jung, Bernd; Oertel, Herbert

    2009-03-01

    A three-dimensional computational fluid dynamics (CFD) method has been developed to simulate the flow in a pumping left ventricle. The proposed method uses magnetic resonance imaging (MRI) technology to provide a patient specific, time dependent geometry of the ventricle to be simulated. Standard clinical imaging procedures were used in this study. A two-dimensional time-dependent orifice representation of the heart valves was used. The location and size of the valves is estimated based on additional long axis images through the valves. A semi-automatic grid generator was created to generate the calculation grid. Since the time resolution of the MR scans does not fit the requirements of the CFD calculations a third order bezier approximation scheme was developed to realize a smooth wall boundary and grid movement. The calculation was performed by a Navier-Stokes solver using the arbitrary Lagrange-Euler (ALE) formulation. Results show that during diastole, blood flow through the mitral valve forms an asymmetric jet, leading to an asymmetric development of the initial vortex ring. These flow features are in reasonable agreement with in vivo measurements but also show an extremely high sensitivity to the boundary conditions imposed at the inflow. Changes in the atrial representation severely alter the resulting flow field. These shortcomings will have to be addressed in further studies, possibly by inclusion of the real atrial geometry, and imply additional requirements for the clinical imaging processes.

  13. Proton irradiation induces persistent and tissue-specific DNA methylation changes in the left ventricle and hippocampus.

    PubMed

    Impey, Soren; Pelz, Carl; Tafessu, Amanuel; Marzulla, Tessa; Turker, Mitchell S; Raber, Jacob

    2016-03-31

    Proton irradiation poses a potential hazard to astronauts during and following a mission, with post-mitotic cells at most risk because they cannot dilute resultant epigenetic changes via cell division. Persistent epigenetic changes that result from environmental exposures include gains or losses of DNA methylation of cytosine, which can impact gene expression. In the present study, we compared the long-term epigenetic effects of whole body proton irradiation in the mouse hippocampus and left ventricle. We used an unbiased genome-wide DNA methylation study, involving ChIP-seq with antibodies to 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) to identify DNA regions in which methylation levels have changed 22 weeks after a single exposure to proton irradiation. We used DIP-Seq to profile changes in genome-wide DNA methylation and hydroxymethylation following proton irradiation. In addition, we used published RNAseq data to assess whether differentially methylated regions were linked to changes in gene expression. The DNA methylation data showed tissue-dependent effects of proton irradiation and revealed significant major pathway changes in response to irradiation that are related to known pathophysiologic processes. Many regions affected in the ventricle mapped to genes involved in cardiovascular function pathways, whereas many regions affected in the hippocampus mapped to genes involved in neuronal functions. In the ventricle, increases in 5hmC were associated with decreases in 5mC. We also observed spatial overlap for regions where both epigenetic marks decreased in the ventricle. In hippocampus, increases in 5hmC were most significantly correlated (spatially) with regions that had increased 5mC, suggesting that deposition of hippocampal 5mC and 5hmC may be mechanistically coupled. The results demonstrate long-term changes in DNA methylation patterns following a single proton irradiation, that these changes are tissue specific, and that they map to

  14. Automated Classification of Disease Patterns from Echo-cardiography Images Based on Shape Features of the Left Ventricle

    SciTech Connect

    Das, Shaoli; Parekh, Ranjan

    2010-10-26

    Computer assisted diagnosis using analysis of medical images is an area of active research in health informatics. This paper proposes a technique for indication of heart diseases by using information related to shapes of the left ventricle (LV). LV boundaries are tracked from echo-cardiography images taken from LV short axis view, corresponding to two disease conditions viz. dilated cardiomyopathy and hypertrophic cardiomyopathy, and discriminated from the normal condition. The LV shapes are modeled using shape histograms generated by plotting the frequency of normalized radii lengths drawn from the centroid to the periphery, against a specific number of bins. A 3-layer neural network activated by a log-sigmoid function is used to classify the shape histograms into one of the three classes. Experimentations on a dataset of 240 images show recognition accuracies of the order of 80%.

  15. Automated Classification of Disease Patterns from Echo-cardiography Images Based on Shape Features of the Left Ventricle

    NASA Astrophysics Data System (ADS)

    Das, Shaoli; Parekh, Ranjan

    2010-10-01

    Computer assisted diagnosis using analysis of medical images is an area of active research in health informatics. This paper proposes a technique for indication of heart diseases by using information related to shapes of the left ventricle (LV). LV boundaries are tracked from echo-cardiography images taken from LV short axis view, corresponding to two disease conditions viz. dilated cardiomyopathy and hypertrophic cardiomyopathy, and discriminated from the normal condition. The LV shapes are modeled using shape histograms generated by plotting the frequency of normalized radii lengths drawn from the centroid to the periphery, against a specific number of bins. A 3-layer neural network activated by a log-sigmoid function is used to classify the shape histograms into one of the three classes. Experimentations on a dataset of 240 images show recognition accuracies of the order of 80%.

  16. System software for the finite element machine

    NASA Technical Reports Server (NTRS)

    Crockett, T. W.; Knott, J. D.

    1985-01-01

    The Finite Element Machine is an experimental parallel computer developed at Langley Research Center to investigate the application of concurrent processing to structural engineering analysis. This report describes system-level software which has been developed to facilitate use of the machine by applications researchers. The overall software design is outlined, and several important parallel processing issues are discussed in detail, including processor management, communication, synchronization, and input/output. Based on experience using the system, the hardware architecture and software design are critiqued, and areas for further work are suggested.

  17. On Hybrid and mixed finite element methods

    NASA Technical Reports Server (NTRS)

    Pian, T. H. H.

    1981-01-01

    Three versions of the assumed stress hybrid model in finite element methods and the corresponding variational principles for the formulation are presented. Examples of rank deficiency for stiffness matrices by the hybrid stress model are given and their corresponding kinematic deformation modes are identified. A discussion of the derivation of general semi-Loof elements for plates and shells by the hybrid stress method is given. It is shown that the equilibrium model by Fraeijs de Veubeke can be derived by the approach of the hybrid stress model as a special case of semi-Loof elements.

  18. Mixed Finite Element Method for Melt Migration

    NASA Astrophysics Data System (ADS)

    Taicher, A. L.; Hesse, M. A.; Arbogast, T.

    2012-12-01

    Multi-phase flow arises during partial melting in the earth mantle, where the porosity is small and material has the characteristics of a compacting porous medium. The equations governing multi-phase flow have been specialized to partially molten materials by McKenzie and Fowler. Their model, also called a Darcy-Stokes system, is highly coupled and non-linear. Melt flow is governed by Darcy's Law while the high temperature, ductile creep of the solid matrix is modeled using viscous non-Newtonian Stokes rheology. In addition, the melt and solid pressures are related through a compaction relation. This nearly elliptic mechanical problem is then coupled with both solute transport and thermal evolution according to the enthalpy method developed by Katz. A suitable numerical method must solve the Darcy-Stokes problem in a manner compatible with the transport problem. Moreover, unlike most porous media problems, partially molten materials transition dynamically from non-porous solid to porous medium. Therefore, a numerical method must also carefully account for the limit of zero porosity. The Darcy-Stokes system for modeling partial melting in the mantle is a novel problem. As far as we know, there currently does not exist a finite element solution in the literature solving these coupled equations. The finite element framework provides support for additional analysis of error and convergence. Moreover, both mesh refinement and anisotropy are naturally incorporated into finite elements. In particular, the mixed finite element method presents a good candidate because it works in both limiting cases: Darcy and incompressible Stokes flow. Mixed methods also produce discretely conservative fluxes that are required for the transport problem to remains stable without violating conservation of mass. Based preliminary investigations in 1D and derived energy estimates, we present a mixed formulation for the Darcy-Stokes system. Next, using novel elements of lowest order and

  19. Iterative methods for mixed finite element equations

    NASA Technical Reports Server (NTRS)

    Nakazawa, S.; Nagtegaal, J. C.; Zienkiewicz, O. C.

    1985-01-01

    Iterative strategies for the solution of indefinite system of equations arising from the mixed finite element method are investigated in this paper with application to linear and nonlinear problems in solid and structural mechanics. The augmented Hu-Washizu form is derived, which is then utilized to construct a family of iterative algorithms using the displacement method as the preconditioner. Two types of iterative algorithms are implemented. Those are: constant metric iterations which does not involve the update of preconditioner; variable metric iterations, in which the inverse of the preconditioning matrix is updated. A series of numerical experiments is conducted to evaluate the numerical performance with application to linear and nonlinear model problems.

  20. TAURUS. 3-D Finite Element Code Postprocessor

    SciTech Connect

    Whirley, R.G.

    1984-05-01

    TAURUS reads the binary plot files generated by the LLNL three-dimensional finite element analysis codes, NIKE3D, DYNA3D, TACO3D, TOPAZ3D, and GEMINI and plots contours, time histories,and deformed shapes. Contours of a large number of quantities may be plotted on meshes consisting of plate, shell, and solid type elements. TAURUS can compute a variety of strain measures, reaction forces along constrained boundaries, and momentum. TAURUS has three phases: initialization, geometry display with contouring, and time history processing.

  1. TAURUS. 3-D Finite Element Code Postprocessor

    SciTech Connect

    Kennedy, T.

    1992-03-03

    TAURUS reads the binary plot files generated by the LLNL three-dimensional finite element analysis codes, NIKE3D, DYNA3D, TACO3D, TOPAZ3D, and GEMINI and plots contours, time histories, and deformed shapes. Contours of a large number of quantities may be plotted on meshes consisting of plate, shell, and solid type elements. TAURUS can compute a variety of strain measures, reaction forces along constrained boundaries, and momentum. TAURUS has three phases: initialization, geometry display with contouring, and time history processing.

  2. TAURUS. 3-D Finite Element Code Postprocessor

    SciTech Connect

    Whirley, R.G.

    1993-11-30

    TAURUS reads the binary plot files generated by the LLNL three-dimensional finite element analysis codes, NIKE3D, DYNA3D, TACO3D, TOPAZ3D, and GEMINI and plots contours, time histories,and deformed shapes. Contours of a large number of quantities may be plotted on meshes consisting of plate, shell, and solid type elements. TAURUS can compute a variety of strain measures, reaction forces along constrained boundaries, and momentum. TAURUS has three phases: initialization, geometry display with contouring, and time history processing.

  3. TAURUS. 3-d Finite Element Code Postprocessor

    SciTech Connect

    Whirley, R.G.

    1991-05-01

    TAURUS reads the binary plot files generated by the LLNL three-dimensional finite element analysis codes, NIKE3D (ESTSC 139), DYNA3D (ESTSC 138), TACO3D (ESTSC 287), TOPAZ3D (ESTSC 231), and GEMINI (ESTSC 455) and plots contours, time histories,and deformed shapes. Contours of a large number of quantities may be plotted on meshes consisting of plate, shell, and solid type elements. TAURUS can compute a variety of strain measures, reaction forces along constrained boundaries, and momentum. TAURUS has three phases: initialization, geometry display with contouring, and time history processing.

  4. TAURUS. 3-d Finite Element Code Postprocessor

    SciTech Connect

    Whirley, R.G.

    1992-03-03

    TAURUS reads the binary plot files generated by the LLNL three-dimensional finite element analysis codes, NIKE3D (ESTSC 139), DYNA3D (ESTSC 138), TACO3D (ESTSC 287), TOPAZ3D (ESTSC 231), and GEMINI (ESTSC 455) and plots contours, time histories,and deformed shapes. Contours of a large number of quantities may be plotted on meshes consisting of plate, shell, and solid type elements. TAURUS can compute a variety of strain measures, reaction forces along constrained boundaries, and momentum. TAURUS has three phases: initialization, geometry display with contouring, and time history processing.

  5. TAURUS. 3-D Finite Element Code Postprocessor

    SciTech Connect

    Whirley, R.G.

    1992-03-03

    TAURUS reads the binary plot files generated by the LLNL three-dimensional finite element analysis codes, NIKE3D, DYNA3D, TACO3D, TOPAZ3D, and GEMINI and plots contours, time histories,and deformed shapes. Contours of a large number of quantities may be plotted on meshes consisting of plate, shell, and solid type elements. TAURUS can compute a variety of strain measures, reaction forces along constrained boundaries, and momentum. TAURUS has three phases: initialization, geometry display with contouring, and time history processing.

  6. A finite element model of ultrasonic extrusion

    NASA Astrophysics Data System (ADS)

    Lucas, M.; Daud, Y.

    2009-08-01

    Since the 1950's researchers have carried out investigations into the effects of applying ultrasonic excitation to metals undergoing elastic and plastic deformation. Experiments have been conducted where ultrasonic excitation is superimposed in complex metalworking operations such as wire drawing and extrusion, to identify the benefits of ultrasonic vibrations. This study presents a finite element analysis of ultrasonic excitation applied to the extrusion of a cylindrical aluminium bar. The effects of friction on the extrusion load are reported for the two excitation configurations of radially and axially applied ultrasonic vibrations and the results are compared with experimental data reported in the literature.

  7. Finite element modelling of buried structures

    NASA Technical Reports Server (NTRS)

    Playdon, D. K.; Simmonds, S. H.

    1984-01-01

    In many structures the final stress states are dependent on the sequence of construction or the stress states at various stages of construction are of interest. Such problems can be analyzed using finite element programs that have the capability of adding (birthing) elements to simulate the progress of construction. However, the usual procedure of assembling elements may lead to numerical instabilities or stress states that are unrealistic. Both problems are demonstrated in the analysis of a structure using the program ADINA. A technique which combines application of a preload with element birthing to overcome these problems is described and illustrated.

  8. Modelling bucket excavation by finite element

    NASA Astrophysics Data System (ADS)

    Pecingina, O. M.

    2015-11-01

    Changes in geological components of the layers from lignite pits have an impact on the sustainability of the cup path elements and under the action of excavation force appear efforts leading to deformation of the entire assembly. Application of finite element method in the optimization of components leads to economic growth, to increase the reliability and durability of the studied machine parts thus the machine. It is obvious usefulness of knowledge the state of mechanical tensions that the designed piece or the assembly not to break under the action of tensions that must cope during operation. In the course of excavation work on all bucket cutting force components, the first coming into contact with the material being excavated cutting edge. Therefore in the study with finite element analysis is retained only cutting edge. To study the field of stress and strain on the cutting edge will be created geometric patterns for each type of cup this will be subject to static analysis. The geometric design retains the cutting edge shape and on this on the tooth cassette location will apply an areal force on the abutment tooth. The cutting edge real pattern is subjected to finite element study for the worst case of rock cutting by symmetrical and asymmetrical cups whose profile is different. The purpose of this paper is to determine the displacement and tensions field for both profiles considering the maximum force applied on the cutting edge and the depth of the cutting is equal with the width of the cutting edge of the tooth. It will consider the worst case when on the structure will act both the tangential force and radial force on the bucket profile. For determination of stress and strain field on the form design of cutting edge profile will apply maximum force assuming uniform distribution and on the edge surface force will apply a radial force. After geometric patterns discretization on the cutting knives and determining stress field, can be seen that at the

  9. Finite Element Analysis of Piping Tees.

    DTIC Science & Technology

    1980-06-01

    Combustion Engineering, Inc., performed an experimental stress analysis3 on an ANSI B16.9 carbon steelt tee designated T-12. Pipe extensions were welded to...AD-ASS? 353 DAVID If TAYLOR NAVAL SHIP RESEARCH AND DEVELOPMENT CE--ETC F/S 13/11 FINITE ELEENT ANALYSIS OF PIPING TEES.(U) JUN 8 A J QUEZON. S C...DAVID W. TAYLOR NAVAL SHIP SRESEARCH AND DEVELOPMENT CENTER Bethesa Md. 20084 FINITE ELEMENT ANALYSIS OF PIPING TEES by Antonio J. Quezon, Gordon C

  10. Algebraic surface design and finite element meshes

    NASA Technical Reports Server (NTRS)

    Bajaj, Chandrajit L.

    1992-01-01

    Some of the techniques are summarized which are used in constructing C sup 0 and C sup 1 continuous meshes of low degree, implicitly defined, algebraic surface patches in three dimensional space. These meshes of low degree algebraic surface patches are used to construct accurate computer models of physical objects. These meshes are also used in the finite element simulation of physical phenomena (e.g., heat dissipation, stress/strain distributions, fluid flow characteristics) required in the computer prototyping of both the manufacturability and functionality of the geometric design.

  11. Finite Element Heat & Mass Transfer Code

    SciTech Connect

    Trease, Lynn

    1996-10-10

    FEHM is a numerical simulation code for subsurface transport processes. It models 3-D, time-dependent, multiphase, multicomponent, non-isothermal, reactive flow through porous and fractured media. It can accurately represent complex 3-D geologic media and structures and their effects on subsurface flow and transport. Its capabilities include flow of gas, water, and heat; flow of air, water, and heat; multiple chemically reactive and sorbing tracers; finite element/finite volume formulation; coupled stress module; saturated and unsaturated media; and double porosity and double porosity/double permeability capabilities.

  12. FEHM. Finite Element Heat & Mass Transfer Code

    SciTech Connect

    Zyvoloski, G.A.

    1996-10-10

    FEHM is a numerical simulation code for subsurface transport processes. It models 3-D, time-dependent, multiphase, multicomponent, non-isothermal, reactive flow through porous and fractured media. It can accurately represent complex 3-D geologic media and structures and their effects on subsurface flow and transport. Its capabilities include flow of gas, water, and heat; flow of air, water, and heat; multiple chemically reactive and sorbing tracers; finite element/finite volume formulation; coupled stress module; saturated and unsaturated media; and double porosity and double porosity/double permeability capabilities.

  13. Chemorheology of reactive systems: Finite element analysis

    NASA Technical Reports Server (NTRS)

    Douglas, C.; Roylance, D.

    1982-01-01

    The equations which govern the nonisothermal flow of reactive fluids are outlined, and the means by which finite element analysis is used to solve these equations for the sort of arbitrary boundary conditions encountered in industrial practice are described. The performance of the computer code is illustrated by several trial problems, selected more for their value in providing insight to polymer processing flows than as practical production problems. Although a good deal remains to be learned as to the performance and proper use of this numerical technique, it is undeniably useful in providing better understanding of today's complicated polymer processing problems.

  14. The M2 muscarinic receptors are essential for signaling in the heart left ventricle during restraint stress in mice.

    PubMed

    Tomankova, Hana; Valuskova, Paulina; Varejkova, Eva; Rotkova, Jana; Benes, Jan; Myslivecek, Jaromir

    2015-01-01

    We hypothesized that muscarinic receptors (MRs) in the heart have a role in stress responses and thus investigated changes in MR signaling (gene expression, number of receptors, adenylyl cyclase (AC), phospholipase C (PLC), protein kinase A and C (PKA and PKC) and nitric oxide synthase [NOS]) in the left ventricle, together with telemetric measurement of heart rate (HR) in mice (wild type [WT] and M2 knockout [KO]) during and after one (1R) or seven sessions (7R) of restraint stress (seven mice per group). Stress decreased M2 MR mRNA and cell surface MR in the left ventricle in WT mice. In KO mice, 1R, but not 7R, decreased surface MR. Similarly, AC activity was decreased in WT mice after 1R and 7R, whereas in KO mice, there was no change. PLC activity was also decreased after 1R in WT and KO mice. This is in accord with the concept that cAMP is a key player in HR regulation. No change was found with stress in NOS activity. Amount of AC and PKA protein was not changed, but was altered for PKC isoenzymes (PKCα, β, γ, η and ϵ (increased) in KO mice, and PKCι (increased) in WT mice). KO mice were more susceptible to stress as shown by inability to compensate HR during 120 min following repeated stress. The results imply that not only M2 but also M3 are involved in stress signaling and in allostasis. We conclude that for a normal stress response, the expression of M2 MR to mediate vagal responses is essential.

  15. Post-mortem computed tomography angiography using left ventricle cardiac puncture: A whole-body, angiographic approach.

    PubMed

    Shao, Yu; Wan, Lei; Zhang, Jianhua; Li, Zhengdong; Liu, Ningguo; Huang, Ping; Zou, Donghua; Chen, Yijiu

    2017-01-01

    Post-mortem computed tomography (PMCT) and PMCT angiography (PMCTA) are rapidly becoming effective and practical methods in forensic medicine. In this article, the authors introduce a whole-body PMCTA approach involving left ventricle cardiac puncture. This procedure was performed in 9 males and 3 females. PMCT was performed first. Then a biopsy core needle was used for a percutaneous puncture into the left ventricle through the intercostal area under CT guidance. 1000 mL of contrast media (diatrizoate meglumine and normal saline [0.9%] at 1:2 ratio) was injected at a rate of 50 mL/8 s, followed by CT scan. Visualization of systemic arteries was achieved in 11 cases, while only partial visualization was achieved in 1 case, which may have been related to incomplete thawing of the cadaver. PMCTA results revealed no vascular diseases and abnormalities in 10 victims. Among the 10 victims, 4 post-scan autopsies were performed and found no vascular abnormalities, consistent with the PMCTA results. Autopsy of the other 6 victims were refused by the relatives. PMCTA revealed signs of internal carotid artery aneurysm inside the sphenoid sinus in one victim, which was confirmed by autopsy. PMCTA results of another victim showed signs of stenosis and blockage of the distal part of the right vertebral artery and basilar artery. Thromboembolism of those arteries was found during autopsy. Compared with other existing PMCTA methods for examination of vascular injuries and diseases, this technique involves simple procedures, is less time consuming, has lower associated costs, does not require specialized equipment, provides adequate imaging quality, and is suitable for centres not equipped with cardiopulmonary bypass machines or other specialized equipment.

  16. Post-mortem computed tomography angiography using left ventricle cardiac puncture: A whole-body, angiographic approach

    PubMed Central

    Li, Zhengdong; Liu, Ningguo; Huang, Ping; Zou, Donghua

    2017-01-01

    Post-mortem computed tomography (PMCT) and PMCT angiography (PMCTA) are rapidly becoming effective and practical methods in forensic medicine. In this article, the authors introduce a whole-body PMCTA approach involving left ventricle cardiac puncture. This procedure was performed in 9 males and 3 females. PMCT was performed first. Then a biopsy core needle was used for a percutaneous puncture into the left ventricle through the intercostal area under CT guidance. 1000 mL of contrast media (diatrizoate meglumine and normal saline [0.9%] at 1:2 ratio) was injected at a rate of 50 mL/8 s, followed by CT scan. Visualization of systemic arteries was achieved in 11 cases, while only partial visualization was achieved in 1 case, which may have been related to incomplete thawing of the cadaver. PMCTA results revealed no vascular diseases and abnormalities in 10 victims. Among the 10 victims, 4 post-scan autopsies were performed and found no vascular abnormalities, consistent with the PMCTA results. Autopsy of the other 6 victims were refused by the relatives. PMCTA revealed signs of internal carotid artery aneurysm inside the sphenoid sinus in one victim, which was confirmed by autopsy. PMCTA results of another victim showed signs of stenosis and blockage of the distal part of the right vertebral artery and basilar artery. Thromboembolism of those arteries was found during autopsy. Compared with other existing PMCTA methods for examination of vascular injuries and diseases, this technique involves simple procedures, is less time consuming, has lower associated costs, does not require specialized equipment, provides adequate imaging quality, and is suitable for centres not equipped with cardiopulmonary bypass machines or other specialized equipment. PMID:28827844

  17. [Functional mitral regurgitation. Physiopathology and impact of medical therapy and surgical techniques for left ventricle reduction].

    PubMed

    Comín, J; Manito, N; Roca, J; Castells, E; Esplugas, E

    1999-07-01

    Functional mitral regurgitation is frequently observed in the setting of left ventricular dyfunction. This finding is a marker of poor outcome in patients with either ischemic or dilated cardiomyopathy. The mechanism accounting for this phenomenon is an altered balance of tethering versus coapting forces acting on the mitral valves in the failing heart. Tethering forces represent an anomalous tension on the mitral valves due to displacement of mitral valve attachments secondary to increased left ventricular chamber sphericity associated with systolic ventricular dysfunction. On the other hand, coapting forces are weak and unable to counteract the abnormal tension acting on the mitral valve, which restricts closure and leads to regurgitation. Vasodilators and inotropic drugs are effective in the management of functional mitral regurgitation. Although partial left ventriculectomy or Batista's procedure is still investigational, this new technique seems to provide an optimal control of functional mitral regurgitation and improve functional capacity and survival of some patients with heart failure.

  18. The effect of an increase in aortic pressure upon the inotropic state of eat and dog left ventricles

    PubMed Central

    Elzinga, G.; Noble, M. I. M.; Stubbs, J.

    1977-01-01

    1. The effect of increased aortic pressure on the inotropic state of the left ventricle was studied in isolated cat hearts, perfused with bovine red cells in Tyrode solution, ejecting into a hydraulic model with the same input impedance as that of the cat aorta. 2. Inotropic state was assessed at a controlled left ventricular end-diastolic pressure by interpolating single isovolumic beats by means of an occluder in the aortic cannula. 3. When such isovolumic beats during periods of raised aortic pressure were compared with those during control periods, the difference in peak isovolumic pressure ranged from -0·3 to +0·5 kPa indicating differences in inotropic state which were small and inconsistent in direction. 4. The maximum rate of rise of left ventricular pressure (dP/dtmax.) of ejecting beats was little affected by a rise of aortic pressure and the direction of changes was inconsistent. 5. The effect of increased aortic pressure was studied in intact dogs after cardiac denervation; left ventricular end-diastolic pressure was uncontrolled and therefore rose to a higher steady level. 6. No consistent change of dP/dtmax. was found during the period of increased aortic pressure. 7. All flow and pressure variables remained steady during the period of increased aortic pressure after the higher level of left ventricular end-diastolic pressure had been established. 8. These results demonstrate that neither the positive inotropic effect nor the negative inotropic effect of increased load dominates in these preparations. This may be the result of a balance between the two effects, or they may be of unimportant magnitude under physiological conditions. ImagesFig. 2Fig. 3 PMID:604450

  19. Myocardial regeneration after implantation of porcine small intestinal submucosa in the left ventricle

    PubMed Central

    Ramos, Cassiana Maria Garcez; Francisco, Julio César; Olandoski, Marcia; de Carvalho, Katherine Athayde Teixeira; Cunha, Ricardo; Erbano, Bruna Olandoski; Jorge, Lianna Ferrari; Baena, Cristina Pellegrino; do Amaral, Vivian Ferreira; Noronha, Lucia; de Macedo, Rafael Michel; Faria-Neto, José Rocha; Guarita-Souza, Luiz César

    2014-01-01

    Introduction Most cardiomyocytes do not regenerate after myocardial infarction. Porcine small intestinal submucosa has been shown to be effective in tissue repair. Objective To evaluate myocardial tissue regeneration and functional effects of SIS implantation in pigs after left ventriculotomy. Methods Fifteen pigs were assigned to two groups: porcine small intestinal submucosa (SIS) (N=10) and control (N=5). The SIS group underwent a mini sternotomy, left ventriculotomy and placement of a SIS patch. The control group underwent a sham procedure. Echocardiography was performed before and 60 days after the surgical procedure. Histological analysis was performed with hematoxylin-eosin stain and markers for actin 1A4, anti sarcomeric actin, connexin43 and factor VIII. Results Weight gain was similar in both groups. Echocardiography analysis revealed no difference between groups regarding end diastolic and systolic diameters and left ventricular ejection fraction, both pre (P=0.118, P=0.313, P=0.944) and post procedure (P=0.333, P=0.522, P=0.628). Both groups showed an increase in end diastolic (P<0,001 for both) and systolic diameter 60 days after surgery (P=0.005, SIS group and P=0.004, control group). New cardiomyocytes, blood vessels and inflammatory reactions were histologically identified in the SIS group. Conclusion SIS implantation in pigs after left ventriculotomy was associated with angiomuscular regeneration and no damage in cardiac function. PMID:25140470

  20. Impeller deflection and modal finite element analysis.

    SciTech Connect

    Spencer, Nathan A.

    2013-10-01

    Deflections of an impeller due to centripetal forces are calculated using finite element analysis. The lateral, or out of plane, deflections are an important design consideration for this particular impeller because it incorporates an air bearing with critical gap tolerances. The target gap distance is approximately 10 microns at a rotational velocity of 2500 rpm. The centripetal forces acting on the impeller cause it deflect in a concave fashion, decreasing the initial gap distance as a function of radial position. This deflection is characterized for a previous and updated impeller design for comparative purposes. The impact of design options such as material selection, geometry dimensions, and operating rotational velocity are also explored, followed by a sensitivity study with these parameters bounded by specific design values. A modal analysis is also performed to calculate the impeller's natural frequencies which are desired to be avoided during operation. The finite element modeling techniques continue to be exercised by the impeller design team to address specific questions and evaluate conceptual designs, some of which are included in the Appendix.

  1. Finite element analysis of multilayer coextrusion.

    SciTech Connect

    Hopkins, Matthew Morgan; Schunk, Peter Randall; Baer, Thomas A.; Mrozek, Randy A.; Lenhart, Joseph Ludlow; Rao, Rekha Ranjana; Collins, Robert; Mondy, Lisa Ann

    2011-09-01

    Multilayer coextrusion has become a popular commercial process for producing complex polymeric products from soda bottles to reflective coatings. A numerical model of a multilayer coextrusion process is developed based on a finite element discretization and two different free-surface methods, an arbitrary-Lagrangian-Eulerian (ALE) moving mesh implementation and an Eulerian level set method, to understand the moving boundary problem associated with the polymer-polymer interface. The goal of this work is to have a numerical capability suitable for optimizing and troubleshooting the coextrusion process, circumventing flow instabilities such as ribbing and barring, and reducing variability in layer thickness. Though these instabilities can be both viscous and elastic in nature, for this work a generalized Newtonian description of the fluid is used. Models of varying degrees of complexity are investigated including stability analysis and direct three-dimensional finite element free surface approaches. The results of this work show how critical modeling can be to reduce build test cycles, improve material choices, and guide mold design.

  2. Finite element analysis of bolted flange connections

    NASA Astrophysics Data System (ADS)

    Hwang, D. Y.; Stallings, J. M.

    1994-06-01

    A 2-D axisymmetric finite element model and a 3-D solid finite element model of a high pressure bolted flange joint were generated to investigate the stress behaviors. This investigation includes comparisons for axisymmetric loading of both the 2-D and 3-D models, the effects of non-axisymmetric bolt pretensions in the 3-D models, and the differences between 2-D and 3-D models subjected to non-axisymmetric loading. Comparisons indicated differences in von Mises stress up to 12% at various points due to the non-axisymmetric bolt pretensions. Applied bending moments were converted to equivalent axial forces for use in the 2-D model. It was found that the largest von Mises stresses in 3-D model did not occur on the side of the connection where the bending stresses and applied axial stresses were additive. Hence, in the 2-D model where the equivalent axial force (for bending moment) and applied axial forces were added, the 2-D model under estimated the maximum von Mises stress obtained from the 3-D model by 30%.

  3. Relationship between the abnormal diastolic vortex structure and impaired left ventricle filling in patients with hyperthyroidism.

    PubMed

    Zhou, Bin-Yu; Xie, Ming-Xing; Wang, Jing; Wang, Xin-Fang; Lv, Qing; Liu, Man-Wei; Kong, Shuang-Shuang; Zhang, Ping-Yu; Liu, Jin-Feng

    2017-04-01

    Intraventricular hydrodynamics plays an important role in evaluating cardiac function. Relationship between diastolic vortex and left ventricular (LV) filling is still rarely elucidated. The aim of this study was to evaluate the evolution of vortex during diastole in hyperthyroidism (HT) and explore the alteration of hydromechanics characteristics with sensitive indexes.Forty-three patients diagnosed with HT were classified into 2 groups according to whether myocardial damage existed: simple hyperthyroid group (HT1, n = 21) and thyrotoxic cardiomyopathy (HT2, n = 22). Twenty-seven age- and gender-matched healthy volunteers were enrolled as the control group. Offline vector flow mapping (VFM model) was used to analyze the LV diastolic blood flow patterns and fluid dynamics. Hemodynamic parameters, vortex area (A), circulation (C), and intraventricular pressure gradient (ΔP), in different diastolic phases (early, mid, and late) were calculated and analyzed.HT2, with a lower E/A ratio and left ventricular ejection fraction (LVEF), had a larger left atrium diameter (LAD) compared with those of the control group and HT1 (P < .05). Compared with the control group, the vortex size and strength, intraventricular pressure gradient during early and mid-diastole were higher in HT1 and lower in HT2 (P < .05). And in late diastole, the vortex size and strength, intraventricular pressure gradient of HT2 became higher than those of the control group (P < .05). Good correlation could be found between CE and E/A (P < .05), CM and ΔPM (P < .01), CL and FT3 (P < .05).VFM is proven practical for detecting the relationship between the changes of left ventricular diastolic vortex and the abnormal left ventricular filling.

  4. [Idiopathic aneurysm of the left ventricle. Apropos of 4 cases operated on with success].

    PubMed

    Rimailho, A; Cabrol, C; Soyer, R; Letac, B; Berteau, P; Fouchard, J; Guérin, F

    1981-04-01

    Over a period of 3 years, 4 cases of idiopathic left ventricular aneurysm, 3 white females and one coloured male aged 34, 53, 29 and 47 years respectively, were observed. All presented with paroxysmal ventricular or supraventricular tachycardia, which, in one case, was severe enough in itself to justify surgery. On angiography, large left ventricular aneurysms bordering the mitral annulus and responsible for moderate mitral regurgitation in two patients were demonstrated. Aneurysmectomy was only possible in 2 cases, the other two having pericardial adhesions with a risk of uncontrollable haemorrhage during dissection being managed by suture of the neck of the aneurysm. The surgical results were very satisfactory, especially with respect to the arrhythmias with a follow-up of 48, 24, 15 and 9 months respectively. In a review of the literature, 93 cases of idiopathic left ventricular aneurysm were analysed, less than 20 of which have been managed surgically. Left ventricular aneurysms seem to be large fibrotic structures located at the border of the mitral, or, less commonly, below the aortic annulus. It is important to differentiate them from congenital left ventricular diverticuli which are usually located at the apex, have muscular walls and are therefore contractile. The aetiology of these aneurysms is unknown: the possible role of myocardial infarction may be excluded as the coronary arteries are always normal on angiography and at autopsy. The relatively young age of the patients is also an argument against this hypothesis. Other suggested causes such as syphilis, tuberculosis, Chagas' disease, non-specific myocarditis, sarcoidosis and thoracic trauma may also be excluded. Surgery seems to be indicated in cases complicated by resistant arrhythmias, peripheral embolism or when the aneurysm increases rapidly in size.

  5. Posterior papillary muscle anchoring affects remote myofiber stress and pump function: finite element analysis.

    PubMed

    Pantoja, Joe Luis; Ge, Liang; Zhang, Zhihong; Morrel, William G; Guccione, Julius M; Grossi, Eugene A; Ratcliffe, Mark B

    2014-10-01

    The role of posterior papillary muscle anchoring (PPMA) in the management of chronic ischemic mitral regurgitation (CIMR) is controversial. We studied the effect of anchoring point direction and relocation displacement on left ventricular (LV) regional myofiber stress and pump function. Previously described finite element models of sheep 16 weeks after posterolateral myocardial infarction (MI) were used. True-sized mitral annuloplasty (MA) ring insertion plus different PPM anchoring techniques were simulated. Anchoring points tested included both commissures and the central anterior mitral annulus; relocation displacement varied from 10% to 40% of baseline diastolic distance from the PPM to the anchor points on the annulus. For each reconstruction scenario, myofiber stress in the MI, border zone, and remote myocardium as well as pump function were calculated. PPMA caused reductions in myofiber stress at end-diastole and end-systole in all regions of the left ventricle that were proportional to the relocation displacement. Although stress reduction was greatest in the MI region, it also occurred in the remote region. The maximum 40% displacement caused a slight reduction in LV pump function. However, with the correction of regurgitation by MA plus PPMA, there was an overall increase in forward stroke volume. Finally, anchoring point direction had no effect on myofiber stress or pump function. PPMA reduces remote myofiber stress, which is proportional to the absolute distance of relocation and independent of anchoring point. Aggressive use of PPMA techniques to reduce remote myofiber stress may accelerate reverse LV remodeling without impairing LV function. Copyright © 2014 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  6. A multigrid solution method for mixed hybrid finite elements

    SciTech Connect

    Schmid, W.

    1996-12-31

    We consider the multigrid solution of linear equations arising within the discretization of elliptic second order boundary value problems of the form by mixed hybrid finite elements. Using the equivalence of mixed hybrid finite elements and non-conforming nodal finite elements, we construct a multigrid scheme for the corresponding non-conforming finite elements, and, by this equivalence, for the mixed hybrid finite elements, following guidelines from Arbogast/Chen. For a rectangular triangulation of the computational domain, this non-conforming schemes are the so-called nodal finite elements. We explicitly construct prolongation and restriction operators for this type of non-conforming finite elements. We discuss the use of plain multigrid and the multilevel-preconditioned cg-method and compare their efficiency in numerical tests.

  7. Inferior wall diverticulum of left ventricle coexisting with mental retardation and atrial septal defect.

    PubMed

    Liu, Henry; Zhou, Ting; Liu, Jiao; Tong, Yiru; Shanewise, Jack S

    2012-10-01

    We report a case of congenital inferior wall left ventricular diverticulum (LVD), atrial septal defect and mental retardation detected by intraoperative transesophageal echocardiography. The combination of three features strongly suggests that genetic factors play important role in the pathogenesis of the disorder. Most LVDs are asymptomatic. Echocardiographers and cardiac anesthesiologists should be aware of this anomaly, and include it in the differential diagnosis of abnormally shaped ventricular wall and seek other congenital abnormalities if LVD is detected.

  8. Fluorouracil induces myocardial ischemia with increases of plasma brain natriuretic peptide and lactic acid but without dysfunction of left ventricle.

    PubMed

    Jensen, Søren Astrup; Hasbak, Philip; Mortensen, Jann; Sørensen, Jens Benn

    2010-12-20

    Fluorouracil (FU) is a cornerstone of colorectal cancer treatment; however, it has clinical and subclinical influence on the heart. This study aimed to clarify the pathophysiology, risk factors, and long-term effects of FU cardiotoxicity. The study prospectively accrued colorectal cancer patients (n=106) completely resected and adjuvantly treated with FU and oxaliplatin according to the FOLFOX4 regimen (infusional FU, folinic acid, and oxaliplatin). Serial measurements were made of systolic and diastolic features of the left ventricle by radionuclide ventriculography, plasma levels of N-terminal pro-brain natriuretic peptide (NT-proBNP), lactic acid, and ECG before chemotherapy, immediately after a treatment infusion, and at follow-up 2 weeks after cessation of the intended 12 treatment courses and were further evaluated by multivariate regression analysis that included cardiovascular history and its risk factors. In the entire cohort, NT-proBNP significantly increased from baseline 14.5±3.2 pmol/L (mean±standard error) to 28.3±5.3 pmol/L during FU therapy (P<.001). Nine patients (8.5%) with cardiotoxicity had significantly higher NT-proBNP of 55.3±40.8 pmol/L compared with 25.4±4.1 pmol/L in those without (P<.001). In multivariate analysis, the FU-induced rise of NT-proBNP was significantly higher in females (P<.001). Plasma lactic acid significantly increased from baseline (1.3±0.1 mmol/L to 1.8±0.1 mmol/L) during FU therapy (P<.001). Left ventricular ejection fraction at baseline of 0.66±0.01 remained unchanged at 0.65±0.01 during FU therapy and 0.66±0.01 at follow-up (P=.4). FU therapy generally induces myocardial neuroendocrine changes with increasing plasma NT-proBNP and lactic acid but without long-term dysfunction of the left ventricle. The usability of NT-proBNP as a predictive marker for FU cardiotoxicity remains to be clarified.

  9. Echo derived variables predicting exercise tolerance in patients with dilated and poorly functioning left ventricle

    PubMed Central

    Webb-Peploe, K; Henein, M; Coats, A; Gibson, D

    1998-01-01

    Objective—To determine whether resting echo derived measurements predict exercise tolerance and its interrelation with heart rate response and ventilation drive in patients with systolic left ventricular disease.
Design—Prospective echocardiographic examination followed by cardiopulmonary exercise testing.
Setting—A tertiary referral centre for cardiac diseases.
Subjects—21 patients (11 with coronary artery disease, 10 with idiopathic dilated cardiomyopathy) with end diastolic dimension > 6.4 cm, shortening fraction< 25%, and in sinus rhythm. There were 11 age matched normal controls.
Results—In the patients, peak oxygen consumption (mV̇O2) correlated with right ventricular long axis excursion (r = 0.62); 65% of the variance in mV̇O2 was predictable using a multivariate model with right ventricular long axis excursion and peak lengthening rate, and peak mitral atrial filling velocity as independent variables. Aetiology was not an independent predictor, although the right ventricular long axis excursion (mean (SD)) was greater in patients with idiopathic dilated cardiomyopathy than in those with coronary artery disease (2.4 (0.5) cm v 1.6 (0.5) cm, p < 0.001). Peak heart rate correlated with duration of mitral regurgitation (r = −0.52) and the slope of ventilation against CO2 production correlated with M mode isovolumic relaxation time (r = 0.61).
Conclusions—In patients with systolic left ventricular dysfunction, more than half the variance in exercise tolerance can be predicted by factors measured on echocardiography at rest, particularly right ventricular long axis excursion.

 Keywords: left ventricular function;  heart failure;  exercise tolerance;  echocardiography PMID:10065024

  10. Effects of halothane on the intramyocardial pressure of the canine left ventricle.

    PubMed

    Nematzadeh, D; Kim, Y D; Rose, J C; Wolf, P H; Macnamara, T E; Kot, P A

    1986-04-01

    In the intact canine heart a gradient of systolic intramyocardial pressure from a minimum at the epicardial region to a maximum at the endocardial region is well established. No information is, however, available regarding the effects of various anaesthetic agents on this gradient. In the present study the effects of halothane on intramyocardial pressure recorded from subendocardial and subepicardial layers of the canine left ventricular free wall were assessed. Experiments were performed on seven anaesthetised mongrel dogs ventilated with 100% oxygen. Intramyocardial pressure was recorded simultaneously from the inner and outer regions of the myocardium using two Mikro-tip pressure transducers. Halothane concentration in the inspired gas varied from 0% to 2%. In the pentobarbital anaesthetised dog halothane does not significantly change the heart rate. With increasing concentrations of halothane in inspired gas systolic intramyocardial pressure at both endocardium and epicardium decreased significantly from control values. As the halothane concentration increased, the normal differential between systolic left ventricular pressure and endocardial intramyocardial pressure was abolished. The intramyocardial pressure gradient from endocardium to epicardium, however, persisted during systole. During diastole the pressure gradient was reversed, becoming maximum in the epicardial region and minimum in the endocardial region in both control and halothane treated animals. Over the range of 0-2% halothane concentration there was no significant effect on the diastolic intramyocardial pressure gradient. These results suggest that halothane affects the myocardial tissue pressure non-uniformly across the left ventricular free wall and therefore influence sth e transmural distribution of coronary blood flow.(ABSTRACT TRUNCATED AT 250 WORDS)

  11. Different degrees of ischaemic injury in the right and left ventricle in cases of severe, nonfatal, pulmonary embolism.

    PubMed

    Fracasso, T; Schrag, B; Sabatasso, S; Lobrinus, J A; Schmeling, A; Mangin, P

    2015-05-01

    Pulmonary fat embolism (PFE) is a common complication of blunt force traumas with bone fractures. Severe forms cause impedance to right ventricular (RV) ejection, with eventual right heart ischaemia and failure. In a prospective study, we have investigated 220 consecutive autopsy cases (73 females, 147 males, mean age 52.1 years, min 14 years, max 91 years). PFE was detected in 52 cases that were divided into three groups according to the degree of PFE (1-3). A fourth group of cases of violent death without PFE was used for comparison. In each case, histology (H&E, Masson) and immunohistochemistry (fibronectin and C5b-9) were performed on six cardiac samples (anterior, lateral and posterior wall of both ventricles). The degree of cardiac damage was registered in each sample and the mean degree of damage was calculated in each case at the RV and left ventricle (LV). Moreover, a parameter ∆ that is the difference between the mean damage at the RV and the LV was calculated in each case. The results were compared within each group and between the groups. In the present study, we could not detect prevalent RV damage in cases of high degree PFE as we did in our previous investigation. In the group PFE3 the difference of the degree of damage between the RV and LV was higher than the one observed in the groups PFE0-2 with the antibody anti-fibronectin. Prevalent right ventricular stress in cases of severe PFE may explain this observation.

  12. A laboratory investigation of the flow in the left ventricle of a human heart with prosthetic, tilting-disk valves

    NASA Astrophysics Data System (ADS)

    Cenedese, A.; del Prete, Z.; Miozzi, M.; Querzoli, G.

    2005-08-01

    The understanding of the phenomena involved in ventricular flow is becoming more and more important because of two main reasons: the continuous improvements in the field of diagnostic techniques and the increasing popularity of prosthetic devices. On one hand, more accurate investigation techniques gives the chance to better diagnose diseases before they become dangerous to the health of the patient. On the other hand, the diffusion of prosthetic devices requires very detailed assessment of the modifications that they introduce in the functioning of the heart. The present work is focussed on the experimental investigation of the flow in the left ventricle of the human heart with the presence of a tilting-disk valve in the mitral position, as this kind of valve is known to change deeply the structure of such a flow. A laboratory model has been built up, which consists of a cavity able to change its volume, representing the ventricle, on which two prosthetic valves are mounted. The facility is designed to be able to reproduce any arbitrarily assigned law of variation of the ventricular volume with time. In the present experiment, a physiologically shaped curve has been used. Velocity was measured using a feature-tracking (FT) algorithm; as a consequence, the particle trajectories are known. The flow has been studied by changing both the beat rate and the stroke volume. The flow was studied both kinematically, examining velocity and vorticity fields, and dynamically, evaluating turbulent and viscous shear stresses, and inertial forces exerted on fluid elements. The analysis of the results allows the identification of the main features of the ventricular flow, generated by a mitral, tilting-disk valve, during the whole cardiac cycle and its dependence on the frequency and the stroke volume.

  13. [False aneurysm of the left ventricle and coronary aneurysms in Behçet disease].

    PubMed

    Rolland, J M; Bical, O; Laradi, A; Robinault, J; Benzidia, R; Vanetti, A; Herreman, G

    1993-09-01

    A false left ventricular aneurysm and coronary artery aneurysm were discovered in a 29 year old patient with Behçet's syndrome. The operation under cardiopulmonary bypass consisted of closing the neck of the false aneurysm by an endo-aneurysmal approach with a Gore-Tex patch. The coronary artery aneurysms were respected. There were no postoperative complications. Cardiac involvement is rare in Behçet's syndrome (6%). The originality of this case is the association of two aneurysmal pathologies: the coronary and ventricular aneurysms due to the angiitis and the myocardial fragility induced by ischaemia.

  14. [Primary liposarcoma of the left ventricle. Apropos of a case and review of the literature].

    PubMed

    Pinelli, G; Trihn, A; Carteaux, J P; Mertes, P M; Dopff, C; Hubert, T; Villemot, J P

    1996-02-01

    Primary malignant myocardial tumours are rare and essentially sarcomas. The authors report a case of primary left ventricular liposarcoma which is the 18th reported case. The presenting signs were of cardiac failure. Metastases are common by the time of diagnosis. Surgical ablation, though rarely complete because of its myocardial localisation, is justified for precise histological diagnosis. The prognosis of these lesions is poor. Complementary treatment is rarely used. However, it should be proposed as surgery alone has been shown to have limited curative applications.

  15. Aortic pressure reduction redistributes transmural blood flow in dog left ventricle

    SciTech Connect

    Smolich, J.J.; Weissberg, P.L.; Broughton, A.; Korner, P.I. )

    1988-02-01

    The authors studied the effect of graded aortic blood pressure reduction on left ventricular (LV) blood flow in anesthetized, autonomically blocked, open-chest dogs at constant heart rate and mean left atrial pressure. Aortic diastolic pressure (ADP) was lowered from rest to 90, 75, and 60 mmHg with an arteriovenous fistula. Global and regional LV blood flow was measured with radioactive microspheres. Mean LV blood flow fell stepwise from 145 ml {center dot} min{sup {minus}1} {center dot} 100 g{sup {minus}1} at rest to 116 ml {center dot} min{sup {minus}1} {center dot} 100 g{sup {minus}1} at ADP of 60 mmHg, whereas the endocardial-to-epicardial flow ratio decreased from 1.20 to 084. The transmural redistribution of LV blood flow was not accompanied by increases in LV oxygen extraction, depression of LV contractility, LV dilatation or LV electrical dysfunction and also occurred in the presence of considerable coronary vasodilator flow reserve. Electrical evidence of subendocardial ischemia appeared at ADP of 32 mmHg and an endocardial-to-epicardial flow ratio of 0.41 in a subgroup of animals. They conclude that the redistribution of LV flow during moderate aortic pressure reduction was an appropriate physiological adjustment to uneven transmural alterations in regional LV wall stress and that it preceded a more pronounced redistribution evident with myocardial ischemia.

  16. Immersed molecular electrokinetic finite element method

    NASA Astrophysics Data System (ADS)

    Kopacz, Adrian M.; Liu, Wing K.

    2013-07-01

    A unique simulation technique has been developed capable of modeling electric field induced detection of biomolecules such as viruses, at room temperatures where thermal fluctuations must be considered. The proposed immersed molecular electrokinetic finite element method couples electrokinetics with fluctuating hydrodynamics to study the motion and deformation of flexible objects immersed in a suspending medium under an applied electric field. The force induced on an arbitrary object due to an electric field is calculated based on the continuum electromechanics and the Maxwell stress tensor. The thermal fluctuations are included in the Navier-Stokes fluid equations via the stochastic stress tensor. Dielectrophoretic and fluctuating forces acting on the particle are coupled through the fluid-structure interaction force calculated within the surrounding environment. This method was used to perform concentration and retention efficacy analysis of nanoscale biosensors using gold particles of various sizes. The analysis was also applied to a human papillomavirus.

  17. Quality management of finite element analysis

    NASA Astrophysics Data System (ADS)

    Barlow, John

    1991-09-01

    A quality management system covering the use of finite element analysis is described. The main topics are as follows: acquisition, development and verification of software (including the software suppliers software quality control system), support, documentation, error control, internal software, software acceptance and release; development and qualification of analysis methods, including software evaluation, analysis procedure qualification and documentation, procedure quality checks, control of analysis procedure errors; product design and integrity analysis, including project quality assurance and analysis planning, task specification and allocation, analysis, execution, results checking and analysis records. Other issues include the commercial and business advantages of quality systems, project and technical management and the training and experience of personnel. The items are correlated with the requirements of International Standard Organization 9001.

  18. Finite element or Galerkin type semidiscrete schemes

    NASA Technical Reports Server (NTRS)

    Durgun, K.

    1983-01-01

    A finite element of Galerkin type semidiscrete method is proposed for numerical solution of a linear hyperbolic partial differential equation. The question of stability is reduced to the stability of a system of ordinary differential equations for which Dahlquist theory applied. Results of separating the part of numerical solution which causes the spurious oscillation near shock-like response of semidiscrete scheme to a step function initial condition are presented. In general all methods produce such oscillatory overshoots on either side of shocks. This overshoot pathology, which displays a behavior similar to Gibb's phenomena of Fourier series, is explained on the basis of dispersion of separated Fourier components which relies on linearized theory to be satisfactory. Expository results represented.

  19. Finite-element solutions for geothermal systems

    NASA Technical Reports Server (NTRS)

    Chen, J. C.; Conel, J. E.

    1977-01-01

    Vector potential and scalar potential are used to formulate the governing equations for a single-component and single-phase geothermal system. By assuming an initial temperature field, the fluid velocity can be determined which, in turn, is used to calculate the convective heat transfer. The energy equation is then solved by considering convected heat as a distributed source. Using the resulting temperature to compute new source terms, the final results are obtained by iterations of the procedure. Finite-element methods are proposed for modeling of realistic geothermal systems; the advantages of such methods are discussed. The developed methodology is then applied to a sample problem. Favorable agreement is obtained by comparisons with a previous study.

  20. Finite-element solutions for geothermal systems

    NASA Technical Reports Server (NTRS)

    Chen, J. C.; Conel, J. E.

    1977-01-01

    Vector potential and scalar potential are used to formulate the governing equations for a single-component and single-phase geothermal system. By assuming an initial temperature field, the fluid velocity can be determined which, in turn, is used to calculate the convective heat transfer. The energy equation is then solved by considering convected heat as a distributed source. Using the resulting temperature to compute new source terms, the final results are obtained by iterations of the procedure. Finite-element methods are proposed for modeling of realistic geothermal systems; the advantages of such methods are discussed. The developed methodology is then applied to a sample problem. Favorable agreement is obtained by comparisons with a previous study.

  1. Waveguide finite elements for curved structures

    NASA Astrophysics Data System (ADS)

    Finnveden, Svante; Fraggstedt, Martin

    2008-05-01

    A waveguide finite element formulation for the analysis of curved structures is introduced. The formulation is valid for structures that along one axis have constant properties. It is based on a modified Hamilton's principle valid for general linear viscoelastic motion, which is derived here. Using this principle, material properties such as losses may be distributed in the system and may vary with frequency. Element formulations for isoparametric solid elements and deep shell elements are presented for curved waveguides as well as for straight waveguides. In earlier works, the curved elements have successfully been used to model a passenger car tyre. Here a simple validation example and convergence study is presented, which considers a finite length circular cylinder and all four elements presented are used, in turn, to model this structure. Calculated results compare favourably to those in the literature.

  2. A finite element model with nonviscous damping

    NASA Technical Reports Server (NTRS)

    Roussos, L. A.; Hyer, M. W.; Thornton, E. A.

    1981-01-01

    A constitutive law by which structural damping is modeled as a relationship between stress, strain, and strain rate in a material is used in conjunction with the finite element method to develop general integral expressions for viscous and nonviscous damping matrices. To solve the set of nonlinear equations resulting from the presence of nonviscous damping, a solution technique is developed by modifying the Newmark method to accommodate an iterative solution and treat the nonviscous damping as a pseudo-force. The technique is then checked for accuracy and convergence in single- and multi-degree-of-freedom problems, and is found to be accurate and efficient for initial-condition problems with small nonviscous damping.

  3. 2-d Finite Element Code Postprocessor

    SciTech Connect

    Sanford, L. A.; Hallquist, J. O.

    1996-07-15

    ORION is an interactive program that serves as a postprocessor for the analysis programs NIKE2D, DYNA2D, TOPAZ2D, and CHEMICAL TOPAZ2D. ORION reads binary plot files generated by the two-dimensional finite element codes currently used by the Methods Development Group at LLNL. Contour and color fringe plots of a large number of quantities may be displayed on meshes consisting of triangular and quadrilateral elements. ORION can compute strain measures, interface pressures along slide lines, reaction forces along constrained boundaries, and momentum. ORION has been applied to study the response of two-dimensional solids and structures undergoing finite deformations under a wide variety of large deformation transient dynamic and static problems and heat transfer analyses.

  4. Adaptive finite element methods in electrochemistry.

    PubMed

    Gavaghan, David J; Gillow, Kathryn; Süli, Endre

    2006-12-05

    In this article, we review some of our previous work that considers the general problem of numerical simulation of the currents at microelectrodes using an adaptive finite element approach. Microelectrodes typically consist of an electrode embedded (or recessed) in an insulating material. For all such electrodes, numerical simulation is made difficult by the presence of a boundary singularity at the electrode edge (where the electrode meets the insulator), manifested by the large increase in the current density at this point, often referred to as the edge effect. Our approach to overcoming this problem has involved the derivation of an a posteriori bound on the error in the numerical approximation for the current that can be used to drive an adaptive mesh-generation algorithm, allowing calculation of the quantity of interest (the current) to within a prescribed tolerance. We illustrate the generic applicability of the approach by considering a broad range of steady-state applications of the technique.

  5. Patient-specific finite element modeling of bones.

    PubMed

    Poelert, Sander; Valstar, Edward; Weinans, Harrie; Zadpoor, Amir A

    2013-04-01

    Finite element modeling is an engineering tool for structural analysis that has been used for many years to assess the relationship between load transfer and bone morphology and to optimize the design and fixation of orthopedic implants. Due to recent developments in finite element model generation, for example, improved computed tomography imaging quality, improved segmentation algorithms, and faster computers, the accuracy of finite element modeling has increased vastly and finite element models simulating the anatomy and properties of an individual patient can be constructed. Such so-called patient-specific finite element models are potentially valuable tools for orthopedic surgeons in fracture risk assessment or pre- and intraoperative planning of implant placement. The aim of this article is to provide a critical overview of current themes in patient-specific finite element modeling of bones. In addition, the state-of-the-art in patient-specific modeling of bones is compared with the requirements for a clinically applicable patient-specific finite element method, and judgment is passed on the feasibility of application of patient-specific finite element modeling as a part of clinical orthopedic routine. It is concluded that further development in certain aspects of patient-specific finite element modeling are needed before finite element modeling can be used as a routine clinical tool.

  6. Finite element analysis enhancement of cryogenic testing

    NASA Astrophysics Data System (ADS)

    Thiem, Clare D.; Norton, Douglas A.

    1991-12-01

    Finite element analysis (FEA) of large space optics enhances cryogenic testing by providing an analytical method by which to ensure that a test article survives proposed testing. The analyses presented in this paper were concerned with determining the reliability of a half meter mirror in an environment where the exact environmental profile was unknown. FEA allows the interaction between the test object and the environment to be simulated to detect potential problems prior to actual testing. These analyses examined worse case scenerios related to cooling the mirror, its structural integrity for the proposed test environment, and deformation of the reflective surface. The FEA was conducted in-house on the System's Reliability Division's VAX 11-750 and Decstation 3100 using Engineering Mechanics Research Corporation's numerically integrated elements for systems analysis finite element software. The results of the analyses showed that it would take at least 48 hours to cool the mirror to its desired testing temperature. It was also determined that the proposed mirror mount would not cause critical concentrated thermal stresses that would fracture the mirror. FEA and actual measurements of the front reflective face were compared and good agreement between computer simulation and physical tests were seen. Space deployment of large optics requires lightweight mirrors which can perform under the harsh conditions of space. The physical characteristics of these mirrors must be well understood in order that their deployment and operation are successful. Evaluating design approaches by analytical simulation, like FEA, verifies the reliability and structural integrity of a space optic during design prior to prototyping and testing. Eliminating an optic's poor design early in its life saves money, materials, and human resources while ensuring performance.

  7. Mixed Finite Element Methods for Melt Migration

    NASA Astrophysics Data System (ADS)

    Taicher, A. L.

    2013-12-01

    Multi-phase flow arises during partial melting in the earth mantle, where the porosity is small and material has the characteristics of a compacting porous medium. The equations governing multi-phase flow have been specialized to partially molten materials by McKenzie and Fowler. Their model, also called a Darcy-Stokes system, is highly coupled and non-linear. Melt flow is governed by Darcy's Law while the high temperature, ductile creep of the solid matrix is modeled using viscous non-Newtonian Stokes rheology. In addition, the melt and solid pressures are related through a compaction relation. This nearly elliptic mechanical problem is then coupled with both solute transport and thermal evolution according to the enthalpy method developed by Katz. A suitable numerical method must solve the Darcy-Stokes problem in a manner compatible with the transport problem. Moreover, unlike most porous media problems, partially molten materials transition dynamically from non-porous solid to porous medium so must carefully account for the limit of zero porosity. The Darcy-Stokes system for modeling partial melting in the mantle is a novel problem. As far as we know, there currently does not exist a finite element solution in the literature solving these coupled equations. In particular, the mixed finite element method presents a good candidate because it works in both limiting cases: Darcy and incompressible Stokes flow. We present a mixed formulation for the Darcy-Stokes system. Next, we present novel elements of lowest order and compatible with both Darcy and Stokes flow Finally, we present our 2D mixed FEM code result for solving Stokes and Darcy flow as well as the coupled Darcy-Stokes system the mid-ocean ridge or corner flow problem.

  8. Inadvertent transarterial lead placement in the left ventricle and aortic cusp: percutaneous lead removal with carotid embolic protection and stent graft placement.

    PubMed

    Kosmidou, Ioanna; Karmpaliotis, Dimitri; Kandzari, David E; Dan, Dan

    2012-11-01

    Transarterial lead implantation in the left ventricle or aorta is a rare complication. Percutaneous lead removal is associated with significant thromboembolic and bleeding risk. We present two cases of lead removal from the left ventricle via the left subclavian artery with concurrent carotid embolic protection followed by stent graft placement in the subclavian artery. Patient 1 underwent prior pacemaker implant with atrial and ventricular active fixation leads positioned in the right coronary cusp and the left ventricle, respectively. Patient 2 had prior ICD implant with a single active fixation lead positioned in the left ventricular apex. Lead removal was performed in a hybrid operating room. Distal embolic filter wires were deployed in the carotid arteries following anticoagulation. Intravascular ultrasound of the left subclavian artery was performed and as the leads were withdrawn, a covered stent was deployed at the removal site. Final angiography demonstrated no evidence of embolic phenomena. Both patients underwent transvenous lead implantation followed by an uneventful postoperative clinical course. Transarterial percutaneous lead removal may be safely performed using embolic filter protection of the cerebral circulation and stent graft placement of the arterial entry site.

  9. Dynamic left ventricular outflow tract obstruction secondary to catecholamine excess in a normal ventricle.

    PubMed

    Mingo, S; Benedicto, A; Jimenez, M C; Pérez, M A; Montero, M

    2006-10-10

    Hypertrophic cardiomyopathy (HCM) is the most common cause of left ventricular outflow tract (LVOT) obstruction. The LVOT obstruction is a consequence of the asymmetric septal hypertrophy and the mitral systolic anterior motion (SAM), causing both of them a dynamic gradient in LVOT. LVOT obstruction has been observed also in other conditions like hypertensive hypertrophy, dehydration, sepsis, vasodilatation, excessive sympathetic stimulation, pericardial tamponade, and after mitral valve repair and aortic valve replacement for aortic stenosis. We report in this document the case of two patients who developed a significant gradient at LVOT in the context of amine treatment during their admission into the intensive unit care. In both, cases there were no gradient, significant hypertrophy or SAM at baseline cardiac evaluation. We have met only one case reported in the literature matching those conditions. In order to treat this type of patients properly, it is essential to take in consideration this pathology.

  10. Improved finite element methodology for integrated thermal structural analysis

    NASA Technical Reports Server (NTRS)

    Dechaumphai, P.; Thornton, E. A.

    1982-01-01

    An integrated thermal-structural finite element approach for efficient coupling of thermal and structural analysis is presented. New thermal finite elements which yield exact nodal and element temperatures for one dimensional linear steady state heat transfer problems are developed. A nodeless variable formulation is used to establish improved thermal finite elements for one dimensional nonlinear transient and two dimensional linear transient heat transfer problems. The thermal finite elements provide detailed temperature distributions without using additional element nodes and permit a common discretization with lower order congruent structural finite elements. The accuracy of the integrated approach is evaluated by comparisons with analytical solutions and conventional finite element thermal structural analyses for a number of academic and more realistic problems. Results indicate that the approach provides a significant improvement in the accuracy and efficiency of thermal stress analysis for structures with complex temperature distributions.

  11. Improved finite element methodology for integrated thermal structural analysis

    NASA Technical Reports Server (NTRS)

    Dechaumphai, P.; Thornton, E. A.

    1982-01-01

    An integrated thermal-structural finite element approach for efficient coupling of thermal and structural analyses is presented. New thermal finite elements which yield exact nodal and element temperature for one dimensional linear steady state heat transfer problems are developed. A nodeless variable formulation is used to establish improved thermal finite elements for one dimensional nonlinear transient and two dimensional linear transient heat transfer problems. The thermal finite elements provide detailed temperature distributions without using additional element nodes and permit a common discretization with lower order congruent structural finite elements. The accuracy of the integrated approach is evaluated by comparisons with analytical solutions and conventional finite element thermal-structural analyses for a number of academic and more realistic problems. Results indicate that the approach provides a significant improvement in the accuracy and efficiency of thermal stress analysis for structures with complex temperature distributions.

  12. Particle tracking velocimetry using echocardiographic data resolves flow in the left ventricle

    NASA Astrophysics Data System (ADS)

    Sampath, Kaushik; Abd, Thura T.; George, Richard T.; Katz, Joseph

    2015-11-01

    Two dimensional contrast echocardiography was performed on patients with a history of left ventricular (LV) thrombus. The 636 x 434 pixels electrocardiograms were recorded using a GE Vivid 9E system with (M5S-D and 4V-D) probes in a 2-D mode at a magnification of 0.3 mm/pix. The concentration of 2-4.5 micron seed bubbles was adjusted to obtain individually discernable traces, and a data acquisition rate of 60-90 fps kept the inter-frame displacements suitable for matching traces, and calculating vectors, but yet low enough to allow a scanning depth and width of upto 13 cm and 60 degrees respectively. Particle tracking velocimetry (PTV) guided by initial particle image velocimetry (PIV) was used to obtain the velocity distributions inside the LV with vector spacing of 3-5 mm. The data quality was greatly enhanced by implementing an iterative particle specific enhancement and tracking algorithm. Data covering 20 heart beats facilitated phase averaging. The results elucidated blood flow in the intra-ventricular septal region, lateral wall region, the apex of the LV and the mitral valve region.

  13. Rupture of posterior wall of left ventricle after mitral valve replacement.

    PubMed Central

    Dark, J H; Bain, W H

    1984-01-01

    Possible aetiological factors, presentation, and management were reviewed in 18 patients with posterior left ventricular rupture complicating mitral valve replacement seen at one centre over six and a half years. The patients were elderly (mean age 57), predominantly women (16 of the 18), and suffering from mitral stenosis. Rupture was much more common after isolated replacement of the mitral valve (16 out of 797 operations) than after double valve replacement (one out 236) or mitral valve replacement and coronary artery bypass graft (one out of 70). A total of 1221 mitral valve replacements were performed over this period, with an overall incidence of rupture of 1.47%. Damage to the valve annulus occurred five times. On four occasions haemorrhage followed a vigorous response to a bolus dose of an inotrope. With the exception of these features, it was difficult to define specific risk factors. Eleven patients bled while still in theatre; one of them survived long term and another four lived for four to 10 days. Repair after restarting cardiopulmonary bypass made short term survival much more likely. In seven rupture developed after return to the intensive therapy unit; again only one survived long term. In nearly all cases bleeding was at, or just below, the atrioventricular groove. Rupture probably occurs after endocardial damage to a thin myocardium that has lost the internal buttress of the subvalvar apparatus. With the rise in intraventricular pressure at the end of bypass blood dissects into the myocardium, resulting in a large haematoma and eventual rupture. Images PMID:6515596

  14. Effect of Trabeculae on the Hemodynamics of an Embryonic Left Ventricle

    NASA Astrophysics Data System (ADS)

    Vedula, Vijay; Lee, Juhyun; Hsiai, Tzung; Marsden, Alison

    2015-11-01

    The left ventricular (LV) endocardium is not smooth, but has ``trabeculae'' protruding into the LV cavity. Recent studies have indicated that trabeculae significantly influence LV hemodynamics by enhancing the diastolic penetration depth of inflow and facilitating a better apical systolic washout. However, it remains unclear how the role of hemodynamics modulates the initiation of trabeculae during cardiac morphogenesis. While such an assessment of mammalian heart models is hampered by the prolonged duration of cardiac development and complexity of surrounding internal organs, embryonic zebrafish is a genetically tractable model for investigating cardiac morphogenesis. We employ a novel light-sheet fluorescent microscopy to extract 4D LV models of zebrafish and develop an ALE-based moving domain CFD solver to perform flow simulations and extract quantitative data related to flow velocities and pressure gradients. We will compare near-wall flow dynamics between the wild type zebrafish (with trabeculae) and the cloche mutant lines that fail to develop trabeculae, to provide new insights into the flow-induced mechano-transduction relevant to the initiation of trabeculae during cardiac morphogenesis. This research is supported by NIH 1R01HL121754-01 grant and Burroughs Wellcome Fund Career Award. Computational resources are provided through the NSF XSEDE grant TG-CTS130034. The light-sheet imaging and zebrafish model are supported by NIH 1R01HL129727.

  15. Structural barrier increases QT-peak dispersion in swine left ventricle in vivo.

    PubMed

    Lu, Sheng; Gong, Yunfan; Iwai, Sei; Stein, Kenneth M; Lerman, Bruce B; Christini, David J

    2006-01-01

    QT dispersion (QTD) is thought to represent the regional nonuniformity of ventricular repolarization and can serve as a prognostic marker for vulnerability to ventricular arrhythmias and risk for sudden cardiac death (SCD). In this study, we used an in vivo swine model to investigate the change of QT-peak dispersion before and after the introduction of a left-ventricular (LV) free-wall structural barrier (SB). Baseline and post-ablation pacing were delivered to: (i) the epicardial LV base, (ii) the epicardial LV apex, and (iii) the right ventricular (RV) endocardium. Four unipolar electrograms were measured from LV free wall epicardial sites referenced to an intrathorax electrode. An SB (approximately 4 x 1 x 1 cm (length, width, depth)) was created by cryoablation in the middle of the two electrode pairs. QTD was computed as the difference between QT-peak intervals for each beat from two electrodes across the SB region from one another. A significant increase of QTD occurred (p<0.05) after the introduction of the SB in all six animals. These results may reflect the accentuation of anatomical repolarization heterogeneity due to SB disruption of electrotonic coupling. Given the link between dispersion of repolarization and initiation of reentry, these findings are consistent with the increased arrhythmia risk of structural heart disease.

  16. Tissue Doppler and strain imaging of left ventricle in Beagle dogs with iatrogenic hypercortisolism

    PubMed Central

    Oui, Heejin; Jeon, Sunghoon; Lee, Gahyun; Park, Seungjo; Cho, Kyoung-Oh

    2015-01-01

    Changes in radial and longitudinal left ventricular (LV) function were investigated in beagles with iatrogenic hypercortisolism. A total of 11 normal dogs were used, and 2 mg/kg prednisone was administered per oral q12 h for 28 days to 7 out of 11 dogs to induce iatrogenic hypercortisolism. Body weight, blood pressure, conventional echocardiography and tissue Doppler imaging (TDI) of normal and iatrogenic hypercortisolism groups were conducted. The myocardial wall velocity of the LV was measured using color TDI and myocardial deformation was determined by the strain and strain rate. Conventional echocardiography revealed that the diastolic LV free wall and interventricular septum in the hypercortisolism group were thickened relative to those in the normal group. The peak early diastolic myocardial velocity and early to late diastolic myocardial velocity ratio of TDI in the hypercortisolism group were significantly lower than those in the normal group. The strain values in the hypercortisolism group were significantly lower than those in the normal group, particularly for longitudinal wall motion. The lower values of myocardium from TDI and strain imaging could be used to investigate subclinical LV systolic and diastolic dysfunction in dogs with the iatrogenic hypercortisolism. PMID:26040612

  17. Tissue Doppler and strain imaging of left ventricle in Beagle dogs with iatrogenic hypercortisolism.

    PubMed

    Oui, Heejin; Jeon, Sunghoon; Lee, Gahyun; Park, Seungjo; Cho, Kyoung-Oh; Choi, Jihye

    2015-01-01

    Changes in radial and longitudinal left ventricular (LV) function were investigated in beagles with iatrogenic hypercortisolism. A total of 11 normal dogs were used, and 2 mg/kg prednisone was administered per oral q12 h for 28 days to 7 out of 11 dogs to induce iatrogenic hypercortisolism. Body weight, blood pressure, conventional echocardiography and tissue Doppler imaging (TDI) of normal and iatrogenic hypercortisolism groups were conducted. The myocardial wall velocity of the LV was measured using color TDI and myocardial deformation was determined by the strain and strain rate. Conventional echocardiography revealed that the diastolic LV free wall and interventricular septum in the hypercortisolism group were thickened relative to those in the normal group. The peak early diastolic myocardial velocity and early to late diastolic myocardial velocity ratio of TDI in the hypercortisolism group were significantly lower than those in the normal group. The strain values in the hypercortisolism group were significantly lower than those in the normal group, particularly for longitudinal wall motion. The lower values of myocardium from TDI and strain imaging could be used to investigate subclinical LV systolic and diastolic dysfunction in dogs with the iatrogenic hypercortisolism.

  18. Creatine kinase kinetics and myocardial infarction in different regions of the left ventricle.

    PubMed

    Sochman, J; Fabián, J; Málek, I; Belán, A; Englis, M

    1989-01-01

    The interval from the onset of infarction pain to culmination of plasma creatine kinase activity (t-peak) was measured in 68 patients with their first myocardial infarction. There is a major difference in this parameter in patients with infarction in the area of the right coronary artery and that supplied by the left anterior descending coronary artery (LAD). While, in 29 patients with infarction in the right coronary artery area, t-peak was 17.7 +/- 4.7 hours, in 39 subjects with infarction in area supplied by the LAD, t-peak was 13.2 +/- 4.6 hours (p less than 0.001). The type of thrombolytic treatment (intravenous or intracoronary, used no difference, just as the time from onset of pain to start of therapy, infarct size and presence or absence of collaterals. A detailed analysis of creatine kinase culmination in relation to the type of artery recanalization is given. The authors conclude that, besides the known factors, creatine kinase culmination is influenced also by the necrosis site, a fact somewhat modifying the informative value of this parameter. However, explanations of this phenomenon are only hypothetical at the present time.

  19. Relationship between cardioscopic images and histological changes in the left ventricle of patients with idiopathic myocarditis†

    PubMed Central

    Uchida, Yasumi; Uchida, Yasuto; Sakurai, Takeshi; Kanai, Masahito; Shirai, Seiichiro; Nakagawa, Osamu; Hiruta, Nobuyuki

    2011-01-01

    Aims Endomyocardial biopsy is essential for definite diagnosis of idiopathic myocarditis. However, since endomyocardial biopsy is guided by fluoroscopy, whether or not the diseased myocardium is biopsied depends on chance, and this may lead to misdiagnosis. If the endocardial surface represents changes indicative of stages of myocarditis, staging of myocarditis and targeted cardioscope-guided biopsy could be used for accurate histological diagnosis. Methods and results The relationship between left ventricular endocardial surface colour observed by cardioscopy and biopsy findings were examined in 78 patients with suspected idiopathic myocarditis. Of these, 59 patients were diagnosed histologically as idiopathic myocarditis. Endocardial colour was classified into red, milky white, purple, yellowish brown, or white. Biopsied specimens with red and milky white wall segments exhibited histological changes compatible with acute myocarditis; purple segments, active chronic myocarditis; and yellowish brown and white segments, inactive chronic myocarditis. The sensitivity, specificity, and predictive value of red and milky white colours for detecting acute myocarditis were 100, 100, and 100%, respectively; of purple for detecting active chronic myocarditis were 83, 92, and 78%, respectively; and yellowish brown and white for detecting inactive chronic myocarditis were 82, 74, and 53, respectively. Conclusion Red and milky white endocardial surface colours predicted histological acute myocarditis, and purple predicted active chronic myocarditis. However, yellowish brown and white colours did not predict inactive chronic myocarditis. PMID:21257727

  20. A semi-automatic method for left ventricle volume estimate: an in vivo validation study

    NASA Technical Reports Server (NTRS)

    Corsi, C.; Lamberti, C.; Sarti, A.; Saracino, G.; Shiota, T.; Thomas, J. D.

    2001-01-01

    This study aims to the validation of the left ventricular (LV) volume estimates obtained by processing volumetric data utilizing a segmentation model based on level set technique. The validation has been performed by comparing real-time volumetric echo data (RT3DE) and magnetic resonance (MRI) data. A validation protocol has been defined. The validation protocol was applied to twenty-four estimates (range 61-467 ml) obtained from normal and pathologic subjects, which underwent both RT3DE and MRI. A statistical analysis was performed on each estimate and on clinical parameters as stroke volume (SV) and ejection fraction (EF). Assuming MRI estimates (x) as a reference, an excellent correlation was found with volume measured by utilizing the segmentation procedure (y) (y=0.89x + 13.78, r=0.98). The mean error on SV was 8 ml and the mean error on EF was 2%. This study demonstrated that the segmentation technique is reliably applicable on human hearts in clinical practice.

  1. Acute Heart Failure and a Pseudo Cystic Image in the Left Ventricle

    PubMed Central

    RIMBAS, Roxana C.; VINEREANU, Dragos

    2014-01-01

    The association between acute heart failure (AHF) and cardiac tumor may change the short and long term management of both conditions. A 51-year-old man presented with signs of AHF. ECG showed sinus tachycardia and left ventricular (LV) hypertrophy. Chest x-Ray found dilated heart and pulmonary congestion. There were no significant changes in blood tests. Transthoracic echocardiography revealed chambers dilation, and LV ejection fraction (LVEF) of 17%. Unexpectedly, we found an apical 2/2 cm cystic image in the LV. This had a myocardium-like membrane, seen better in 3D echocardiography, suggestive for hydatic cyst. Cerebral, thoracic, and abdomino-pelvic CT scan showed no hydatic lesions. Anti-Echinococcus antibodies were negative. Initially the clinical challenge was the management of the tumor in a patient with AHF and dilated cardiomyopathy. He was treated for AHF and followed up for the cystic image. He exhibited significant improvement of the clinical status and LVEF (increased to 42 %), with important cardiac reverse remodeling. Surprisingly, the apical cystic image disappeared. However, we found a hypertrophic aberrant cordae from apex to mid-septum, in the same position as the previous image. Thus, we believe that this cordae, by important remodeling and torsion generated the cystic image. This case highlights the importance of serial 2D and 3D echo examinations in patients with severely remodeled LV, and also with tumoral images. PMID:25705277

  2. A semi-automatic method for left ventricle volume estimate: an in vivo validation study

    NASA Technical Reports Server (NTRS)

    Corsi, C.; Lamberti, C.; Sarti, A.; Saracino, G.; Shiota, T.; Thomas, J. D.

    2001-01-01

    This study aims to the validation of the left ventricular (LV) volume estimates obtained by processing volumetric data utilizing a segmentation model based on level set technique. The validation has been performed by comparing real-time volumetric echo data (RT3DE) and magnetic resonance (MRI) data. A validation protocol has been defined. The validation protocol was applied to twenty-four estimates (range 61-467 ml) obtained from normal and pathologic subjects, which underwent both RT3DE and MRI. A statistical analysis was performed on each estimate and on clinical parameters as stroke volume (SV) and ejection fraction (EF). Assuming MRI estimates (x) as a reference, an excellent correlation was found with volume measured by utilizing the segmentation procedure (y) (y=0.89x + 13.78, r=0.98). The mean error on SV was 8 ml and the mean error on EF was 2%. This study demonstrated that the segmentation technique is reliably applicable on human hearts in clinical practice.

  3. The Clinical Benefits of Adding a Third Dimension to Assess the Left Ventricle with Echocardiography

    PubMed Central

    Badano, Luigi P.

    2014-01-01

    Three-dimensional echocardiography is a novel imaging technique based on acquisition and display of volumetric data sets in the beating heart. This permits a comprehensive evaluation of left ventricular (LV) anatomy and function from a single acquisition and expands the diagnostic possibilities of noninvasive cardiology. It provides the possibility of quantitating geometry and function of LV without preestablished assumptions regarding cardiac chamber shape and allows an echocardiographic assessment of the LV that is less operator-dependent and therefore more reproducible. Further developments and improvements for widespread routine applications include higher spatial and temporal resolution to improve image quality, faster acquisition, processing and reconstruction, and fully automated quantitative analysis. At present, three-dimensional echocardiography complements routine 2DE in clinical practice, overcoming some of its limitations and offering additional valuable information that has led to recommending its use for routine assessment of the LV of patients in whom information about LV size and function is critical for their clinical management. PMID:24959374

  4. The Spatial Distribution of Actin and Mechanical Cycle of Myosin Are Different in Right and Left Ventricles of Healthy Mouse Hearts

    PubMed Central

    2014-01-01

    The contraction of the right ventricle (RV) expels blood into the pulmonary circulation, and the contraction of the left ventricle (LV) pumps blood into the systemic circulation through the aorta. The respective afterloads imposed on the LV and RV by aortic and pulmonary artery pressures create very different mechanical requirements for the two ventricles. Indeed, differences have been observed in the contractile performance between left and right ventricular myocytes in dilated cardiomyopathy, in congestive heart failure, and in energy usage and speed of contraction at light loads in healthy hearts. In spite of these functional differences, it is commonly believed that the right and left ventricular muscles are identical because there were no differences in stress development, twitch duration, work performance, or power among the RV and LV in dogs. This report shows that on a mesoscopic scale [when only a few molecules are studied (here three to six molecules of actin) in ex vivo ventricular myofibrils], the two ventricles in rigor differ in the degree of orientational disorder of actin within in filaments and during contraction in the kinetics of the cross-bridge cycle. PMID:25488019

  5. Improved finite-element methods for rotorcraft structures

    NASA Technical Reports Server (NTRS)

    Hinnant, Howard E.

    1991-01-01

    An overview of the research directed at improving finite-element methods for rotorcraft airframes is presented. The development of a modification to the finite element method which eliminates interelement discontinuities is covered. The following subject areas are discussed: geometric entities, interelement continuity, dependent rotational degrees of freedom, and adaptive numerical integration. This new methodology is being implemented as an anisotropic, curvilinear, p-version, beam, shell, and brick finite element program.

  6. Impact of new computing systems on finite element computations

    NASA Technical Reports Server (NTRS)

    Noor, A. K.; Storassili, O. O.; Fulton, R. E.

    1983-01-01

    Recent advances in computer technology that are likely to impact finite element computations are reviewed. The characteristics of supersystems, highly parallel systems, and small systems (mini and microcomputers) are summarized. The interrelations of numerical algorithms and software with parallel architectures are discussed. A scenario is presented for future hardware/software environment and finite element systems. A number of research areas which have high potential for improving the effectiveness of finite element analysis in the new environment are identified.

  7. Fast left ventricle tracking in CMR images using localized anatomical affine optical flow

    NASA Astrophysics Data System (ADS)

    Queirós, Sandro; Vilaça, João. L.; Morais, Pedro; Fonseca, Jaime C.; D'hooge, Jan; Barbosa, Daniel

    2015-03-01

    In daily cardiology practice, assessment of left ventricular (LV) global function using non-invasive imaging remains central for the diagnosis and follow-up of patients with cardiovascular diseases. Despite the different methodologies currently accessible for LV segmentation in cardiac magnetic resonance (CMR) images, a fast and complete LV delineation is still limitedly available for routine use. In this study, a localized anatomically constrained affine optical flow method is proposed for fast and automatic LV tracking throughout the full cardiac cycle in short-axis CMR images. Starting from an automatically delineated LV in the end-diastolic frame, the endocardial and epicardial boundaries are propagated by estimating the motion between adjacent cardiac phases using optical flow. In order to reduce the computational burden, the motion is only estimated in an anatomical region of interest around the tracked boundaries and subsequently integrated into a local affine motion model. Such localized estimation enables to capture complex motion patterns, while still being spatially consistent. The method was validated on 45 CMR datasets taken from the 2009 MICCAI LV segmentation challenge. The proposed approach proved to be robust and efficient, with an average distance error of 2.1 mm and a correlation with reference ejection fraction of 0.98 (1.9 +/- 4.5%). Moreover, it showed to be fast, taking 5 seconds for the tracking of a full 4D dataset (30 ms per image). Overall, a novel fast, robust and accurate LV tracking methodology was proposed, enabling accurate assessment of relevant global function cardiac indices, such as volumes and ejection fraction

  8. Left ventricle: automated segmentation by using myocardial effusion threshold reduction and intravoxel computation at MR imaging.

    PubMed

    Codella, Noel C F; Weinsaft, Jonathan W; Cham, Matthew D; Janik, Matthew; Prince, Martin R; Wang, Yi

    2008-09-01

    This retrospective analysis of existing patient data had institutional review board approval and was performed in compliance with HIPAA. No informed consent was required. The purpose of the study was to develop and validate an algorithm for automated segmentation of the left ventricular (LV) cavity that accounts for papillary and/or trabecular muscles and partial voxels in cine magnetic resonance (MR) images, an algorithm called LV Myocardial Effusion Threshold Reduction with Intravoxel Computation (LV-METRIC). The algorithm was validated in biologic phantoms, and its results were compared with those of manual tracing, as well as those of a commercial automated segmentation software (MASS [MR Analytical Software System]), in 38 subjects. LV-METRIC accuracy in vitro was 98.7%. Among the 38 subjects studied, LV-METRIC and MASS ejection fraction estimations were highly correlated with manual tracing (R(2) = 0.97 and R(2) = 0.95, respectively). Ventricular volume estimations were smaller with LV-METRIC and larger with MASS than those calculated by using manual tracing, though all results were well correlated (R(2) = 0.99). LV-METRIC volume measurements without partial voxel interpolation were statistically equivalent to manual tracing results (P > .05). LV-METRIC had reduced intraobserver and interobserver variability compared with other methods. MASS required additional manual intervention in 58% of cases, whereas LV-METRIC required no additional corrections. LV-METRIC reliably and reproducibly measured LV volumes. http://radiology.rsnajnls.org/cgi/content/full/248/3/1004/DC1. RSNA, 2008

  9. The visceral pericardium: macromolecular structure and contribution to passive mechanical properties of the left ventricle

    PubMed Central

    Jöbsis, Paul D.; Ashikaga, Hiroshi; Wen, Han; Rothstein, Emily C.; Horvath, Keith A.; McVeigh, Elliot R.; Balaban, Robert S.

    2010-01-01

    Much attention has been focused on the passive mechanical properties of the myocardium, which determines left ventricular (LV) diastolic mechanics, but the significance of the visceral pericardium (VP) has not been extensively studied. A unique en face three-dimensional volumetric view of the porcine VP was obtained using two-photon excitation fluorescence to detect elastin and backscattered second harmonic generation to detect collagen, in addition to standard light microscopy with histological staining. Below a layer of mesothelial cells, collagen and elastin fibers, extending several millimeters, form several distinct layers. The configuration of the collagen and elastin layers as well as the location of the VP at the epicardium providing a geometric advantage led to the hypothesis that VP mechanical properties play a role in the residual stress and passive stiffness of the heart. The removal of the VP by blunt dissection from porcine LV slices changed the opening angle from 53.3 ± 10.3 to 27.3 ± 5.7° (means ± SD, P < 0.05, n = 4). In four porcine hearts where the VP was surgically disrupted, a significant decrease in opening angle was found (35.5 ± 4.0°) as well as a rightward shift in the ex vivo pressure-volume relationship before and after disruption and a decrease in LV passive stiffness at lower LV volumes (P < 0.05). These data demonstrate the significant and previously unreported role that the VP plays in the residual stress and passive stiffness of the heart. Alterations in this layer may occur in various disease states that effect diastolic function. PMID:17933976

  10. Consistent regional heterogeneity of passive diastolic stretch and systolic deformation in the healthy heart: age-related changes in left ventricle contractility.

    PubMed

    Jasaityte, Ruta; D'hooge, Jan; Herbots, Lieven; Daraban, Ana M; Rademakers, Frank; Claus, Piet

    2014-01-01

    The consistency of the normal spatial distribution of segmental passive stretch (PreS) and systolic strain (SS) within the left ventricle was investigated and a recently proposed echocardiographic estimate of left ventricular (LV) contractility was used to detect contractility changes with age. Hereto, in 54 healthy subjects, segmental PreS and SS were measured on tissue Doppler images of six left ventricle walls. For each subject, a linear regression line was estimated through the segmental PreS and SS values. The slopes and intercepts of this PreS-SS relationship did not differ between age groups, suggesting no changes in LV contractility with age. Moreover, a consistent regional distribution of PreS was observed, with the highest values measured in the septum, resulting in a similar distribution of SS as a direct consequence of the Frank-Starling mechanism.

  11. Leapfrog/Finite Element Method for Fractional Diffusion Equation

    PubMed Central

    Zhao, Zhengang; Zheng, Yunying

    2014-01-01

    We analyze a fully discrete leapfrog/Galerkin finite element method for the numerical solution of the space fractional order (fractional for simplicity) diffusion equation. The generalized fractional derivative spaces are defined in a bounded interval. And some related properties are further discussed for the following finite element analysis. Then the fractional diffusion equation is discretized in space by the finite element method and in time by the explicit leapfrog scheme. For the resulting fully discrete, conditionally stable scheme, we prove an L 2-error bound of finite element accuracy and of second order in time. Numerical examples are included to confirm our theoretical analysis. PMID:24955431

  12. Factors Influencing the twisting and untwisting properties of the left ventricle during normal pregnancy.

    PubMed

    Papadopoulou, Elektra; Kaladaridou, Anna; Agrios, John; Matthaiou, John; Pamboukas, Constantinos; Toumanidis, Savvas

    2014-02-01

    During pregnancy, important hemodynamic changes occur, consistent with an increase in preload and decrease in afterload and systemic vascular resistance. The aim of the present study was to investigate the changes in left ventricular (LV) strain and rotational properties during the 3 trimesters of normal pregnancy and to examine the factors that drive these changes. Twenty-seven pregnant women (29.7 ± 6.9 years) and 11 age-matched nonpregnant controls (29.9 ± 5.4 years) were evaluated. Conventional echocardiography and two-dimensional speckle tracking imaging were performed at 8-12 (1st trimester), 21-28 (2nd trimester), and 33-36 (3rd trimester) weeks of pregnancy. LV rotation, twist, untwisting rate, and circumferential strain were measured using the parasternal short-axis views at basal and apical levels. Global longitudinal strain was calculated from the LV apical views. Peak LV twist and peak untwisting rate increased significantly in the 3rd trimester of normal pregnancy (13.48 ± 2.90°, 13.12 ± 3.30°, 16.83 ± 3.61°, P < 0.001; and -111.52 ± 23.54°/sec, -107.40 ± 26.58°/sec, -144.30 ± 45.14°/sec, P < 0.001; in the 1st, 2nd, and 3rd trimester, respectively). Global longitudinal and circumferential strain of the apex decreased significantly from the 2nd trimester. An independent association was found between the change in LV twist and the change in LV end-systolic volume between the 1st and 3rd trimester. Peak untwisting rate at the 3rd trimester correlated significantly with peak twist and LV end-diastolic volume. During normal pregnancy, LV twist and peak untwisting rate increase in the 3rd trimester and correlate with end-systolic and end-diastolic volume, respectively. Circumferential strain of the apex and global longitudinal strain decrease from the 2nd trimester. © 2013, Wiley Periodicals, Inc.

  13. Apoptosis in the left ventricle of chronic volume overload causes endocardial endothelial dysfunction in rats.

    PubMed

    Cox, Michael J; Sood, Harpreet S; Hunt, Matthew J; Chandler, Derrick; Henegar, Jeffrey R; Aru, Giorgio M; Tyagi, Suresh C

    2002-04-01

    The hypothesis is that chronic increases in left ventricular (LV) load induce oxidative stress and latent matrix metalloproteinase (MMP) is activated, allowing the heart to dilate in the absence of endothelial nitric oxide (NO) and thereby reduce filling pressure. To create volume overload, an arteriovenous (A-V) fistula was placed in male Sprague-Dawley rats. To decrease oxidative stress and apoptosis, 0.08 mg/ml nicotinamide (Nic) was administered in drinking water 2 days before surgery. The rats were divided into the following groups: 1) A-V fistula, 2) A-V fistula + Nic, 3) sham operated, 4) sham + Nic, and 5) control (unoperated); n = 6 rats/group. After 4 wk, hemodynamic parameters were measured in anesthetized rats. The heart was removed and weighed, and LV tissue homogeneates were prepared. A-V fistula caused an increase in heart weight, lung weight, and end-diastolic pressure compared with the sham group. The levels of malondialdehyde (MDA; a marker of oxidative stress) was 6.60 +/- 0.23 ng/mg protein and NO was 6.87 +/- 1.21 nmol/l in the LV of A-V fistula rats by spectrophometry. Nic treatment increased NO to 13.88 +/- 2.5 nmol/l and decreased MDA to 3.54 +/- 0.34 ng/mg protein (P = 0.005). Zymographic levels of MMP-2 were increased, as were protein levels of nitrotyrosine and collagen fragments by Western blot analysis. The inhibition of oxidative stress by Nic decreased nitrotyrosine content and MMP activity. The levels of tissue inhibitor of metalloproteinase-4 mRNA were decreased in A-V fistula rats and increased in A-V fistula rats treated with Nic by Northern blot analysis. TdT-mediated dUTP nick-end labeling-positive cells were increased in A-V fistula rats and decreased in fistula rats treated with Nic. Acetylcholine and nitroprusside responses in cardiac rings prepared from the above groups of rats suggest impaired endothelial-dependent cardiac relaxation. Treatment with Nic improves cardiac relaxation. The results suggest that an increase in

  14. Relationship between changes of chamber mechanical parameters and mean pressure-mean flow diagrams of the left ventricle.

    PubMed

    Negroni, J A; Lascano, E C; Pichel, R H

    1988-01-01

    A theoretical relationship between mean ventricular pressure (P) and mean ventricular outflow (Q) was developed based on a model of the left ventricle with elastic-resistive properties. Using a polynomial interpolation method, a fifth-order polynomial equation for the P-Q relationship was obtained. Its coefficients are functions of end-diastolic volume (VD), heart rate (HR), contractile state (CS), diastolic elastance (ED), asymmetry (S) of the elastance function E(t), and ventricular internal resistance factor (K). Effect of changes of these parameters indicated that normal and enhanced CS relations diverge toward the P axis but have a common intercept toward the Q axis. A similar effect was obtained with increased asymmetry of E(t). Changes in VD, HR and ED produced a parallel shift of the P-Q relation. The effect of K was negligible, however, which would reduce the description of the P-Q relationship to a third-order polynomial equation. A flow-dependent deactivation component was introduced, altering the asymmetry factor S, which decreases in a linear proportion to Q. This factor shifted the pump function graph downwards. We conclude that the theoretical description of the P-Q relation we present reproduces the experimental behavior of pump function diagrams reported in the literature (changes in VD, HR, and CS) and predicts the possible behavior due to other parameter changes.

  15. Studying the influence of hydrogel injections into the infarcted left ventricle using the element-free Galerkin method.

    PubMed

    Legner, D; Skatulla, S; MBewu, J; Rama, R R; Reddy, B D; Sansour, C; Davies, N H; Franz, T

    2014-03-01

    Myocardial infarction is an increasing health problem worldwide. Because of an under-supply of blood, the cardiomyocytes in the affected region permanently lose their ability to contract. This in turn gradually weakens the overall heart function. A new therapeutic approach based on the injection of a gel into the infarcted area aims to support the healing and to inhibit adverse remodelling that can lead to heart failure. A computational model is the basis for obtaining a better understanding of the heart mechanics, in particular, how myocardial infarction and gel injections affect its pumping performance. A strain invariant-based stored energy function is proposed to account for the passive mechanical behaviour of the model, which also makes provision for active contraction. To incorporate injections an additive homogenization approach is introduced. The numerical framework is developed using an in-house code based on the element-free Galerkin method. The main focus of this contribution is to investigate the influence of gel injections on the mechanics of the left ventricle during the diastolic filling and systolic isovolumetric (isochoric) contraction phases. It is found that gel injections are able to reduce the elevated fibre stresses caused by an infarct. Copyright © 2013 John Wiley & Sons, Ltd.

  16. Speckle tracking for left ventricle performance in young athletes with bicuspid aortic valve and mild aortic regurgitation.

    PubMed

    Stefani, Laura; De Luca, Alessio; Maffulli, Nicola; Mercuri, Roberto; Innocenti, Gabriele; Suliman, Irina; Toncelli, Loira; Vono, Maria Concetta; Cappelli, Brunello; Pedri, Stefano; Pedrizzetti, Gianni; Galanti, Giorgio

    2009-06-01

    Longitudinal peak systolic strain (LPSS) quantifies regional and global heart function. Few data are available on left ventricle (LV) performance in young athletes with bicuspid aortic valve (BAV), where a pattern of mild aortic insufficiency is relatively frequent, and the ejection fraction (EF) is often normal for a long time. We report the measurement of LV strain in young BAV athletes. Three groups (20 athletes with BAV, 20 healthy athletes, and 20 sedentary healthy subjects, all aged 25 +/- 3 years) underwent standard echo examination to evaluate LPSS at the basal and medium-apical segments of the lateral wall (LW) and interventricular septum (IVS) of the LV. LPSS was within the normal range; however, in BAV athletes, the LPSS of the basal segments tended to be lower (S%IVS(basal), -17.7 +/- 2.7; S%LW(basal), -14.2 +/- 2.2; S%IVS(med-apic), -21 +/- 3.5; S%LW(med-apic), -18.8 +/- 4.2), producing a gradient from basal to apical regions. The EF was normal in all subjects. Young trained BAV athletes have normal LV performance. Nevertheless, these athletes tend to have lower strain than healthy subjects in the LV basal segments. The clinical implications of this finding are uncertain and require further investigation.

  17. Female rats with severe left ventricle volume overload exhibit more cardiac hypertrophy but fewer myocardial transcriptional changes than males.

    PubMed

    Beaumont, Catherine; Walsh-Wilkinson, Élisabeth; Drolet, Marie-Claude; Roussel, Élise; Arsenault, Marie; Couet, Jacques

    2017-04-07

    Aortic valve regurgitation (AR) imposes a volume overload (VO) to the left ventricle (LV). Male rats with a pathological heart overload usually progress more quickly towards heart failure than females. We examined whether a sexual dimorphism exists in the myocardial transcriptional adaptations to AR. Adult Wistar male and female rats either underwent a sham operation or were induced with AR and then followed for 26 weeks. Female AR rats gained relatively more LV mass than males (75 vs. 42%). They had a similar increase in LV chamber dimensions compared to males but more wall thickening. On the other hand, fatty acid oxidation (FAO)-related LV enzyme activity was only decreased in AR males. The expression of genes encoding FAO-related enzymes was only reduced in AR males and not in females. A similar situation was observed for the expression of genes involved in mitochondrial biogenesis or function as well as for genes encoding for transcription factors implicated in the control of bioenergetics and mitochondrial function (Errα, Errγ or Pgc1α). Although females develop more LV hypertrophy from severe VO, their myocardial gene expression remains closer to normal. This could provide survival benefits for females with severe VO.

  18. Fluid-structure interaction of an aortic heart valve prosthesis driven by an animated anatomic left ventricle.

    PubMed

    Le, Trung Bao; Sotiropoulos, Fotis

    2013-07-01

    We develop a novel large-scale kinematic model for animating the left ventricle (LV) wall and use this model to drive the fluid-structure interaction (FSI) between the ensuing blood flow and a mechanical heart valve prosthesis implanted in the aortic position of an anatomic LV/aorta configuration. The kinematic model is of lumped type and employs a cell-based, FitzHugh-Nagumo framework to simulate the motion of the LV wall in response to an excitation wavefront propagating along the heart wall. The emerging large-scale LV wall motion exhibits complex contractile mechanisms that include contraction (twist) and expansion (untwist). The kinematic model is shown to yield global LV motion parameters that are well within the physiologic range throughout the cardiac cycle. The FSI between the leaflets of the mechanical heart valve and the blood flow driven by the dynamic LV wall motion and mitral inflow is simulated using the curvilinear immersed boundary (CURVIB) method [1, 2] implemented in conjunction with a domain decomposition approach. The computed results show that the simulated flow patterns are in good qualitative agreement with in vivo observations. The simulations also reveal complex kinematics of the valve leaflets, thus, underscoring the need for patient-specific simulations of heart valve prosthesis and other cardiac devices.

  19. Electrical Wave Propagation in an Anisotropic Model of the Left Ventricle Based on Analytical Description of Cardiac Architecture

    PubMed Central

    Pravdin, Sergey F.; Dierckx, Hans; Katsnelson, Leonid B.; Solovyova, Olga; Markhasin, Vladimir S.; Panfilov, Alexander V.

    2014-01-01

    We develop a numerical approach based on our recent analytical model of fiber structure in the left ventricle of the human heart. A special curvilinear coordinate system is proposed to analytically include realistic ventricular shape and myofiber directions. With this anatomical model, electrophysiological simulations can be performed on a rectangular coordinate grid. We apply our method to study the effect of fiber rotation and electrical anisotropy of cardiac tissue (i.e., the ratio of the conductivity coefficients along and across the myocardial fibers) on wave propagation using the ten Tusscher–Panfilov (2006) ionic model for human ventricular cells. We show that fiber rotation increases the speed of cardiac activation and attenuates the effects of anisotropy. Our results show that the fiber rotation in the heart is an important factor underlying cardiac excitation. We also study scroll wave dynamics in our model and show the drift of a scroll wave filament whose velocity depends non-monotonically on the fiber rotation angle; the period of scroll wave rotation decreases with an increase of the fiber rotation angle; an increase in anisotropy may cause the breakup of a scroll wave, similar to the mother rotor mechanism of ventricular fibrillation. PMID:24817308

  20. Drift of Scroll Wave Filaments in an Anisotropic Model of the Left Ventricle of the Human Heart

    PubMed Central

    Pravdin, Sergei; Dierckx, Hans; Markhasin, Vladimir S.; Panfilov, Alexander V.

    2015-01-01

    Scroll waves are three-dimensional vortices which occur in excitable media. Their formation in the heart results in the onset of cardiac arrhythmias, and the dynamics of their filaments determine the arrhythmia type. Most studies of filament dynamics were performed in domains with simple geometries and generic description of the anisotropy of cardiac tissue. Recently, we developed an analytical model of fibre structure and anatomy of the left ventricle (LV) of the human heart. Here, we perform a systematic study of the dynamics of scroll wave filaments for the cases of positive and negative tension in this anatomical model. We study the various possible shapes of LV and different degree of anisotropy of cardiac tissue. We show that, for positive filament tension, the final position of scroll wave filament is mainly determined by the thickness of the myocardial wall but, however, anisotropy attracts the filament to the LV apex. For negative filament tension, the filament buckles, and for most cases, tends to the apex of the heart with no or slight dependency on the thickness of the LV. We discuss the mechanisms of the observed phenomena and their implications for cardiac arrhythmias. PMID:26539486

  1. Fluid mechanics of blood flow in human fetal left ventricles based on patient-specific 4D ultrasound scans.

    PubMed

    Lai, Chang Quan; Lim, Guat Ling; Jamil, Muhammad; Mattar, Citra Nurfarah Zaini; Biswas, Arijit; Yap, Choon Hwai

    2016-10-01

    The mechanics of intracardiac blood flow and the epigenetic influence it exerts over the heart function have been the subjects of intense research lately. Fetal intracardiac flows are especially useful for gaining insights into the development of congenital heart diseases, but have not received due attention thus far, most likely because of technical difficulties in collecting sufficient intracardiac flow data in a safe manner. Here, we circumvent such obstacles by employing 4D STIC ultrasound scans to quantify the fetal heart motion in three normal 20-week fetuses, subsequently performing 3D computational fluid dynamics simulations on the left ventricles based on these patient-specific heart movements. Analysis of the simulation results shows that there are significant differences between fetal and adult ventricular blood flows which arise because of dissimilar heart morphology, E/A ratio, diastolic-systolic duration ratio, and heart rate. The formations of ventricular vortex rings were observed for both E- and A-wave in the flow simulations. These vortices had sufficient momentum to last until the end of diastole and were responsible for generating significant wall shear stresses on the myocardial endothelium, as well as helicity in systolic outflow. Based on findings from previous studies, we hypothesized that these vortex-induced flow properties play an important role in sustaining the efficiency of diastolic filling, systolic pumping, and cardiovascular flow in normal fetal hearts.

  2. Image-driven cardiac left ventricle segmentation for the evaluation of multiview fused real-time 3-dimensional echocardiography images.

    PubMed

    Rajpoot, Kashif; Noble, J Alison; Grau, Vicente; Szmigielski, Cezary; Becher, Harald

    2009-01-01

    Real-time 3-dimensional echocardiography (RT3DE) permits the acquisition and visualization of the beating heart in 3D. Despite a number of efforts to automate the left ventricle (LV) delineation from RT3DE images, this remains a challenging problem due to the poor nature of the acquired images usually containing missing anatomical information and high speckle noise. Recently, there have been efforts to improve image quality and anatomical definition by acquiring multiple single-view RT3DE images with small probe movements and fusing them together after alignment. In this work, we evaluate the quality of the multiview fused images using an image-driven semiautomatic LV segmentation method. The segmentation method is based on an edge-driven level set framework, where the edges are extracted using a local-phase inspired feature detector for low-contrast echocardiography boundaries. This totally image-driven segmentation method is applied for the evaluation of end-diastolic (ED) and end-systolic (ES) single-view and multiview fused images. Experiments were conducted on 17 cases and the results show that multiview fused images have better image segmentation quality, but large failures were observed on ED (88.2%) and ES (58.8%) single-view images.

  3. Real-time tracking of the left ventricle in 3D echocardiography using a state estimation approach.

    PubMed

    Orderud, Fredrik; Hansgård, Jøger; Rabben, Stein I

    2007-01-01

    In this paper we present a framework for real-time tracking of deformable contours in volumetric datasets. The framework supports composite deformation models, controlled by parameters for contour shape in addition to global pose. Tracking is performed in a sequential state estimation fashion, using an extended Kalman filter, with measurement processing in information space to effectively predict and update contour deformations in real-time. A deformable B-spline surface coupled with a global pose transform is used to model shape changes of the left ventricle of the heart. Successful tracking of global motion and local shape changes without user intervention is demonstrated on a dataset consisting of 21 3D echocardiography recordings. Real-time tracking using the proposed approach requires a modest CPU load of 13% on a modern computer. The segmented volumes compare to a semi-automatic segmentation tool with 95% limits of agreement in the interval 4.1 +/- 24.6 ml (r = 0.92).

  4. Structure and Functional Characteristics of Rat's Left Ventricle Cardiomyocytes under Antiorthostatic Suspension of Various Duration and Subsequent Reloading

    PubMed Central

    Ogneva, I. V.; Mirzoev, T. M.; Biryukov, N. S.; Veselova, O. M.; Larina, I. M.

    2012-01-01

    The goal of the research was to identify the structural and functional characteristics of the rat's left ventricle under antiorthostatic suspension within 1, 3, 7 and 14 days, and subsequent 3 and 7-day reloading after a 14-day suspension. The transversal stiffness of the cardiomyocyte has been determined by the atomic force microscopy, cell respiration—by polarography and proteins content—by Western blotting. Stiffness of the cortical cytoskeleton increases as soon as one day after the suspension and increases up to the 14th day, and starts decreasing during reloading, reaching the control level after 7 days. The stiffness of the contractile apparatus and the intensity of cell respiration also increases. The content of non-muscle isoforms of actin in the cytoplasmic fraction of proteins does not change during the whole experiment, as does not the beta-actin content in the membrane fraction. The content of gamma-actin in the membrane fraction correlates with the change in the transversal stiffness of the cortical cytoskeleton. Increased content of alpha-actinin-1 and alpha-actinin-4 in the membrane fraction of proteins during the suspension is consistent with increased gamma-actin content there. The opposite direction of change of alpha-actinin-1 and alpha-actinin-4 content suggests their involvement into the signal pathways. PMID:23093854

  5. Prediction of cardiac events in patients with transient left ventricle dilation on stress myocardial perfusion SPECT images.

    PubMed

    Fukuda, Hiroshi; Moroi, Masao

    2005-10-01

    The purpose of this study was to investigate cardiac events in patients with transient left ventricle (LV) dilation on stress myocardial perfusion single-photon emission computed tomography images (MPI). Consecutive patients (n=53, 31 males, mean age 71 years) with transient LV dilation on thallium-201 stress MPI (treadmill: 21, pharmacologic: 32) were followed for 17 months. Follow-up time was censored at the occurrence of cardiac death, congestive heart failure, acute coronary syndrome, or revascularization. Images were scored and then the summed stress score (SSS), summed rest score, and summed difference score were calculated. Cardiac death occurred in 3 patients, hospitalization occurred in 8 patients, and revascularization occurred in 20 patients. The combined cardiac event rate was 59% (76% for exercise stress vs 47% for pharmacologic stress, p=0.034). Cox regression analysis demonstrated that a combination of higher SSS and slow washout rate was the best predictor of cardiac events (hazard ratio =3.3, p=0.029). A high cardiac event rate is associated with transient LV dilation on thallium-201 stress MPI. The event rate is particularly high for exercise stress MPI. Furthermore, a combination of the SSS and thallium-201 slow washout is the best predictor of cardiac events in patients with transient LV dilation.

  6. Fluid-structure interaction of an aortic heart valve prosthesis driven by an animated anatomic left ventricle

    NASA Astrophysics Data System (ADS)

    Le, Trung Bao; Sotiropoulos, Fotis

    2013-07-01

    We develop a novel large-scale kinematic model for animating the left ventricle (LV) wall and use this model to drive the fluid-structure interaction (FSI) between the ensuing blood flow and a mechanical heart valve prosthesis implanted in the aortic position of an anatomic LV/aorta configuration. The kinematic model is of lumped type and employs a cell-based, FitzHugh-Nagumo framework to simulate the motion of the LV wall in response to an excitation wavefront propagating along the heart wall. The emerging large-scale LV wall motion exhibits complex contractile mechanisms that include contraction (twist) and expansion (untwist). The kinematic model is shown to yield global LV motion parameters that are well within the physiologic range throughout the cardiac cycle. The FSI between the leaflets of the mechanical heart valve and the blood flow driven by the dynamic LV wall motion and mitral inflow is simulated using the curvilinear immersed boundary (CURVIB) method (Ge and Sotiropoulos, 2007; Borazjani et al., 2008) [1,2] implemented in conjunction with a domain decomposition approach. The computed results show that the simulated flow patterns are in good qualitative agreement with in vivo observations. The simulations also reveal complex kinematics of the valve leaflets, thus, underscoring the need for patient-specific simulations of heart valve prosthesis and other cardiac devices.

  7. First third filling parameters of left ventricle assessed from gated equilibrium studies in patients with various heart diseases

    SciTech Connect

    Adatepe, M.H.; Nichols, K.; Powell, O.M.; Isaacs, G.H.

    1984-01-01

    The authors determined the first third filling fraction (1/3 FF), the maximum filling rate (1/3 FR) and the mean filling rate (1/3 MFR) for the first third diastolic filling period of the left ventricle in patients with coronary artery disease (CAD), valvular heart disease (VHD), pericardial effusion (PE), cardiomyopathies (CM), chronic obstructive lung disease (COPD) and in 5 normals-all from resting gated equilibrium studies. Parameters are calculated from the third order Fourier fit to the LV volume curve and its derivative. 1/3 FF% = 1/3 diastolic count - end systolic count / 1/3 diastolic count x 100. Patients with CAD are divided into two groups: Group I with normal ejection fraction (EF) and wall motion (WM); Group II with abnormal EF and WM. Results are shown in the table. Abnormal filling parameters are found not only in CAD but in VHD, PE and CM. The authors conclude that the first third LV filling parameters are sensitive but non-specific indicators of filling abnormalities caused by diverse etiologic factors. Abnormal first third filling parameters may occur in the presence of a normal resting EF and WM in CAD.

  8. Dynamic Dyssynchrony and Impaired Contractile Reserve of the Left Ventricle in Beta-Thalassaemia Major: An Exercise Echocardiographic Study

    PubMed Central

    Cheung, Yiu-fai; Yu, Wei; Li, Shu-na; Lam, Wendy W. M.; Ho, Yuen-chi; Wong, Sophia J.; Chan, Godfrey C. F.; Ha, Shau-yin

    2012-01-01

    Background Performance of the left ventricle during exercise stress in thalassaemia patients is uncertain. We aimed to explore the phenomenon of dynamic dyssynchrony and assess contractile reserve in patients with beta-thalassaemia major and determine their relationships with myocardial iron load. Methods and Results Thirty-two thalassaemia patients (16 males), aged 26.8±6.9 years, without heart failure and 17 healthy controls were studied. Their left ventricular (LV) volumes, ejection fraction, systolic dyssynchrony index (SDI), and myocardial acceleration during isovolumic LV contraction (IVA) were determined at rest and during submaximal bicycle exercise testing using 3-dimensional and tissue Doppler echocardiography. Myocardial iron load as assessed by T2* cardiac magnetic resonance in patients were further related to indices of LV dyssynchrony and contractile reserve. At rest, patients had significantly greater LV SDI (p<0.001) but similar IVA (p = 0.22) compared with controls. With exercise stress, the prevalence of mechanical dyssynchrony (SDI>4.6%, control+2SD) increased from baseline 25% to 84% in patients. Δ SDIexercise-baseline correlated with exercise-baseline differences in LV ejection fraction (p<0.001) and stroke volume (p = 0.006). Compared with controls, patients had significantly less exercise-induced increase in LV ejection fraction, cardiac index, and IVA (interaction, all p<0.05) and had impaired contractile reserve as reflected by the gentler IVA-heart rate slope (p = 0.018). Cardiac T2* in patients correlated with baseline LV SDI (r = −0.44, p = 0.011) and IVA-heart rate slope (r = 0.36, p = 0.044). Conclusions Resting LV dyssynchrony is associated with myocardial iron load. Exercise stress further unveils LV dynamic dyssynchrony and impaired contractile reserve in patients with beta-thalassaemia major. PMID:23028894

  9. Importance of detection of segmental wall motion abnormalities of left ventricle in nontraumatic subarachnoid hemorrhage: a prospective study.

    PubMed

    Jyotsna, Maddury; Prasad, Vannemreddy; Indrani, Garre; Trikamji, Bhavesh Vasant

    2010-05-01

    To find out the incidence and importance of segmental wall motion abnormalities (SWMAs) of the left ventricle in noncoronary artery disease (CAD) and nontraumatic subarachnoid hemorrhage (SAH) patients. Nontraumatic SAH patients were evaluated with two-dimensional echocardiogram in addition to detailed clinical and investigative data. In echocardiogram, LV was evaluated as a 16-segment approach and its function was noted. Cerebral angiogram was performed in all the patients. Repeat echocardiograms were performed on day 10 and 6 weeks later. In 56 nontraumatic SAH patients, the average age was 45.8 + or - 9.1 years. Among them 16 were females. Clinical grade was 3-5 in 26 (46.43%) patients and 24 (42.86%) patients had aneurysms. Echocardiogram was normal in 33 patients and in 23 (41.07%) patients there were left ventricular (LV) abnormalities. LV SWMA was present in 15 patients (65.22%) and global hypokinesia in 8 patients (34.78 %). In the SWMA group, preservation of apical function relative to the base was observed in 13 patients. The repeat echocardiogram on day 10 in SWMA group showed normalization of LV abnormalities in 14 patients and one patient died due to rebleed. In global hypokinesia group, four patients recovered and four died. Significant associations were observed between SWMA and presence of aneurysm (P < 0.05) and LV function (P < 0.001), mortality correlated with LV function (P < 0.001) and clinical grade (P < 0.02). Transient SWMA can occur due to aneurysmal SAH itself and when associated with LV dysfunction, it had a higher mortality. (Echocardiography 2010;27:496-500).

  10. Significance of dipyridamole-induced transient dilation of the left ventricle during thallium-201 scintigraphy in suspected coronary artery disease

    SciTech Connect

    Chouraqui, P.; Rodrigues, E.A.; Berman, D.S.; Maddahi, J. )

    1990-09-15

    The occurrence and significance of transient dilation of the left ventricle during dipyridamole stress-redistribution thallium-201 scintigraphy was studied in 73 patients who underwent both dipyridamole thallium-201 study and coronary angiography. Transient dilation ratio was calculated from planar anterior images by dividing the computer-derived left ventricular area on the initial image by that of the 4-hour image. In 11 patients with normal coronary arteriograms or less than 50% coronary stenosis, the transient dilation ratio was 0.98 +/- 0.046. An abnormal transient dilation ratio was defined as greater than or equal to 1.12, representing greater than or equal to 3 standard deviations above the mean normal value. When the 15 patients with an abnormal ratio were compared with the 58 with a normal ratio, the former group had a significantly higher frequency of 3 critical (greater than or equal to 90%) coronary stenoses (33 vs 5%), higher prevalence of collaterals (67 vs 24%), more extensive myocardial reversible defects by planar (71 vs 10%) or by single-photon emission computed tomography (87.5 vs 35%) imaging and a higher incidence of dipyridamole-induced anginal chest pain (53 vs 22%). No significant difference between the 2 groups was noted with respect to age, gender, prior myocardial infarction, single or double critical coronary stenosis, dipyridamole-induced ischemic electrocardiographic response and increased lung uptake. An abnormal transient dilation ratio of greater than or equal to 1.12 was a specific marker of multivessel (87%) or 3-vessel (85%) critical coronary artery disease.

  11. The impact of a hyperdynamic left ventricle on right ventricular function measurements in preterm infants with a patent ductus arteriosus.

    PubMed

    Breatnach, Colm R; Franklin, Orla; James, Adam T; McCallion, Naomi; El-Khuffash, Afif

    2017-09-01

    Right ventricular (RV) functional assessment in premature infants includes basal longitudinal strain (RV BLS), RV systolic tissue Doppler velocity (RV s'), tricuspid annular plane systolic excursion (TAPSE) and RV fractional area change (FAC). A hyperdynamic left ventricle (LV) may influence RV measures of displacement (TAPSE) and velocity (RV s') but not measures of relative change of length (RV BLS) or area (FAC). We aimed to explore this hypothesis in preterm infants with a patent ductus arteriosus (PDA). We measured LV function (ejection fraction (LV EF); left ventricular output) and RV function (RV BLS; RV s'; TAPSE; FAC) on days 1, 2 and 5-7 in infants <29 weeks. The cohort was divided based on PDA presence by days 5-7. LV and RV function measurements were compared between the groups using two-way analysis of variance with repeated measures. 121 infants with a mean (SD) gestation and birth weight of 26.8 (1.4) weeks and 968 (250) g were enrolled. By days 5-7, the PDA remained open in 83 (69%), with evidence of hyperdynamic LV function. There was no difference in RV s' (5.3 (0.9) vs 5.1 (1.0) cm/s, p=0.3) or TAPSE (6.2 (1.3) vs 6.1 (1.2) mm, p=0.7) between infants with and without a PDA, but infants in the PDA group had lower RV FAC (41 (8) vs 47 (10) %, p<0.01) and lower RV BLS (-24.2 (5.0) vs -26.2 (4.1) %, p=0.03). LV influence on RV functional parameters must be taken into account when interpreting of RV function using those techniques. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  12. Ceramic bracket design: an analysis using the finite element method.

    PubMed

    Ghosh, J; Nanda, R S; Duncanson, M G; Currier, G F

    1995-12-01

    This investigation was designed to generate finite element models for selected ceramic brackets and graphically display the stress distribution in the brackets when subjected to arch wire torsion and tipping forces. Six commercially available ceramic brackets, one monocrystalline and five polycrystalline alumina, of twin bracket design for the permanent maxillary left central incisor were studied. Three-dimensional computer models of the brackets were constructed and loading forces, similar to those applied by a full-size (0.0215 x 0.028 inch) stainless steel arch wire in torsion and tipping necessary to fracture ceramic brackets, were applied to the models. Stress levels were recorded at relevant points common among the various brackets. High stress levels were observed at areas of abrupt change in geometry and shape. The design of the wire slot and wings for the Contour bracket (Class One Orthodontic Products, Lubbock, Texas) and of the outer edges of the wire slot for the Allure bracket (GAC, Central Islip, N.Y.) were found to be good in terms of even stress distribution. The brackets with an isthmus connecting the wings seemed to resist stresses better than the one bracket that did not have this feature. The design of the isthmus for the Transcend (Unitek/3M, Monrovia, Calif.) and Lumina (Ormco, Glendora, Calif.) brackets were found to be acceptable as well. The Starfire bracket ("A" Company, San Diego, Calif.) showed high stresses and irregular stress distribution, because it had sharp angles, no rounded corners, and no isthmus. The finite element method proved to be a useful tool in the stress analysis of ceramic orthodontic brackets subjected to various forces.(ABSTRACT TRUNCATED AT 250 WORDS)

  13. Efficient finite element modeling of elastodynamic scattering

    NASA Astrophysics Data System (ADS)

    Wilcox, Paul D.; Velichko, Alexander

    2009-03-01

    The scattering of elastic waves by defects is the physical basis of ultrasonic NDE. Although analytical models exist for some canonical problems, the general case of scattering from an arbitrarily-shaped defect requires numerical methods such as finite elements (FE). In this paper, a robust and efficient FE technique is presented that is based on the premise of meshing a relatively small domain sufficient to enclose the scatterer. Plane waves are then excited from a particular direction by a numerical implementation of the Helmholtz-Kirchhoff integral that uses an encircling array of uni-modal point sources. The scattered field displacements are recorded at the same points and the field decomposed into plane waves of different modes at different angles. By repeating this procedure for different incident angles it is possible to generate the scattering- or S-matrix for the scatterer. For a given size of scatterer, all the information in an S-matrix can be represented in the Fourier domain by a limited number of complex coefficients. Thus the complete scattering behavior of an arbitrary-shaped scatterer can be characterized by a finite number of complex coefficients, that can be obtained from a relatively small number of FE model executions.

  14. A composite nodal finite element for hexagons

    SciTech Connect

    Hennart, J.P.; Mund, E.H. |; Valle, E. Del

    1997-10-01

    A nodal algorithm for the solution of the multigroup diffusion equations in hexagonal arrays is analyzed. Basically, the method consists of dividing each hexagon into four quarters and mapping the hexagon quarters onto squares. The resulting boundary value problem on a quadrangular domain is solved in primal weak formulation. Nodal finite element methods like the Raviart-Thomas RTk schemes provide accurate analytical expansions of the solution in the hexagons. Transverse integration cannot be performed on the equations in the quadrangular domain as simply as it is usually done on squares because these equations have essentially variable coefficients. However, by considering an auxiliary problem with constant coefficients (on the same quadrangular domain) and by using a preconditioning approach, transverse integration can be performed as for rectangular geometry. A description of the algorithm is given for a one-group diffusion equation. Numerical results are presented for a simple model problem with a known analytical solution and for k{sub eff} evaluations of some benchmark problems proposed in the literature. For the analytical problem, the results indicate that the theoretical convergence orders of RTk schemes (k = 0,1) are obtained, yielding accurate solutions at the expense of a few preconditioning iterations.

  15. Finite element modelling of fabric shear

    NASA Astrophysics Data System (ADS)

    Lin, Hua; Clifford, Mike J.; Long, Andrew C.; Sherburn, Martin

    2009-01-01

    In this study, a finite element model to predict shear force versus shear angle for woven fabrics is developed. The model is based on the TexGen geometric modelling schema, developed at the University of Nottingham and orthotropic constitutive models for yarn behaviour, coupled with a unified displacement-difference periodic boundary condition. A major distinction from prior modelling of fabric shear is that the details of picture frame kinematics are included in the model, which allows the mechanisms of fabric shear to be represented more accurately. Meso- and micro-mechanisms of deformation are modelled to determine their contributions to energy dissipation during shear. The model is evaluated using results obtained for a glass fibre plain woven fabric, and the importance of boundary conditions in the analysis of deformation mechanisms is highlighted. The simulation results show that the simple rotation boundary condition is adequate for predicting shear force at large deformations, with most of the energy being dissipated at higher shear angles due to yarn compaction. For small deformations, a detailed kinematic analysis is needed, enabling the yarn shear and rotation deformation mechanisms to be modelled accurately.

  16. Finite element analysis of arc welding

    SciTech Connect

    Friedman, E.

    1980-01-01

    Analytical models of the gas tungsten-arc welding process into finite element computer programs provides a valuable tool for determining the welding thermal cycle, weld bead shape, and penetration characteristics, as well as for evaluating the stresses and distortions generated as a result of the temperature transients. The analysis procedures are applicable to planar or axisymmetric welds with arbitrary cross-sectional geometries, under quasistationary conditions. The method used for determining temperatures features an iteration procedure to accurately account for the latent heat absorbed during melting and liberated during solidification of the weld. By simulating the heat input from the arc to the workpiece by a normal distribution function, temperature transients, weld bead dimensions, and cooling rates are evaluated as functions of both the magnitude and distribution of heat input, weldment geometry, and weld speed (or duration of heating for stationary arcs). Modeling of the welding thermal cycle is a prerequisite to analytical treatments of metallurgical changes in weld metal and heat-affected zone material, residual stresses and distortions, and weld defects. A quasistationary formulation for moving welds enables temperatures to be calculated using a two-dimensional heat conduction computer program. The present limitation of high welding speed can, however, be relaxed without altering the two-dimensional framework of the procedure.

  17. An iterative algorithm for finite element analysis

    NASA Astrophysics Data System (ADS)

    Laouafa, F.; Royis, P.

    2004-03-01

    In this paper, we state in a new form the algebraic problem arising from the one-field displacement finite element method (FEM). The displacement approach, in this discrete form, can be considered as the dual approach (force or equilibrium) with subsidiary constraints. This approach dissociates the nonlinear operator to the linear ones and their sizes are linear functions of integration rule which is of interest in the case of reduced integration. This new form of the problem leads to an inexpensive improvement of FEM computations, which acts at local, elementary and global levels. We demonstrate the numerical performances of this approach which is independent of the mesh structure. Using the GMRES algorithm we build, for nonsymmetric problems, a new algorithm based upon the discretized field of strain. The new algorithms proposed are more closer to the mechanical problem than the classical ones because all fields appear during the resolution process. The sizes of the different operators arising in these new forms are linear functions of integration rule, which is of great interest in the case of reduced integration.

  18. TACO: a finite element heat transfer code

    SciTech Connect

    Mason, W.E. Jr.

    1980-02-01

    TACO is a two-dimensional implicit finite element code for heat transfer analysis. It can perform both linear and nonlinear analyses and can be used to solve either transient or steady state problems. Either plane or axisymmetric geometries can be analyzed. TACO has the capability to handle time or temperature dependent material properties and materials may be either isotropic or orthotropic. A variety of time and temperature dependent loadings and boundary conditions are available including temperature, flux, convection, and radiation boundary conditions and internal heat generation. Additionally, TACO has some specialized features such as internal surface conditions (e.g., contact resistance), bulk nodes, enclosure radiation with view factor calculations, and chemical reactive kinetics. A user subprogram feature allows for any type of functional representation of any independent variable. A bandwidth and profile minimization option is also available in the code. Graphical representation of data generated by TACO is provided by a companion post-processor named POSTACO. The theory on which TACO is based is outlined, the capabilities of the code are explained, the input data required to perform an analysis with TACO are described. Some simple examples are provided to illustrate the use of the code.

  19. VALIDATION OF ANSYS FINITE ELEMENT ANALYSIS SOFTWARE

    SciTech Connect

    HAMM, E.R.

    2003-06-27

    This document provides a record of the verification and Validation of the ANSYS Version 7.0 software that is installed on selected CH2M HILL computers. The issues addressed include: Software verification, installation, validation, configuration management and error reporting. The ANSYS{reg_sign} computer program is a large scale multi-purpose finite element program which may be used for solving several classes of engineering analysis. The analysis capabilities of ANSYS Full Mechanical Version 7.0 installed on selected CH2M Hill Hanford Group (CH2M HILL) Intel processor based computers include the ability to solve static and dynamic structural analyses, steady-state and transient heat transfer problems, mode-frequency and buckling eigenvalue problems, static or time-varying magnetic analyses and various types of field and coupled-field applications. The program contains many special features which allow nonlinearities or secondary effects to be included in the solution, such as plasticity, large strain, hyperelasticity, creep, swelling, large deflections, contact, stress stiffening, temperature dependency, material anisotropy, and thermal radiation. The ANSYS program has been in commercial use since 1970, and has been used extensively in the aerospace, automotive, construction, electronic, energy services, manufacturing, nuclear, plastics, oil and steel industries.

  20. Accurate finite element modeling of acoustic waves

    NASA Astrophysics Data System (ADS)

    Idesman, A.; Pham, D.

    2014-07-01

    In the paper we suggest an accurate finite element approach for the modeling of acoustic waves under a suddenly applied load. We consider the standard linear elements and the linear elements with reduced dispersion for the space discretization as well as the explicit central-difference method for time integration. The analytical study of the numerical dispersion shows that the most accurate results can be obtained with the time increments close to the stability limit. However, even in this case and the use of the linear elements with reduced dispersion, mesh refinement leads to divergent numerical results for acoustic waves under a suddenly applied load. This is explained by large spurious high-frequency oscillations. For the quantification and the suppression of spurious oscillations, we have modified and applied a two-stage time-integration technique that includes the stage of basic computations and the filtering stage. This technique allows accurate convergent results at mesh refinement as well as significantly reduces the numerical anisotropy of solutions. We should mention that the approach suggested is very general and can be equally applied to any loading as well as for any space-discretization technique and any explicit or implicit time-integration method.

  1. Intra Plate Stresses Using Finite Element Modelling

    NASA Astrophysics Data System (ADS)

    Jayalakshmi, S.; Raghukanth, S. T. G.

    2016-10-01

    One of the most challenging problems in the estimation of seismic hazard is the ability to quantify seismic activity. Empirical models based on the available earthquake catalogue are often used to obtain activity of source regions. The major limitation with this approach is the lack of sufficient data near a specified source. The non-availability of data poses difficulties in obtaining distribution of earthquakes with large return periods. Such events recur over geological time scales during which tectonic processes, including mantle convection, formation of faults and new plate boundaries, are likely to take place. The availability of geometries of plate boundaries, plate driving forces, lithospheric stress field and GPS measurements has provided numerous insights on the mechanics of tectonic plates. In this article, a 2D finite element model of Indo-Australian plate is developed with the focus of representing seismic activity in India. The effect of large scale geological features including sedimentary basins, fold belts and cratons on the stress field in India is explored in this study. In order to address long term behaviour, the orientation of stress field and tectonic faults of the present Indo- Australian plate are compared with a reconstructed stress field from the early Miocene (20 Ma).

  2. [Pulmonary artery sling and single ventricle treated with a simultaneous operation of slide tracheoplasty, left pulmonary artery reimplantation, and bidirectional cavo-pulmonary shunt].

    PubMed

    Kawahito, Tomohisa; Takano, Shinji; Egawa, Yoshiyasu; Iwamura, Yoshinobu; Nakahara, Yasuo; Nii, Akira; Ohnishi, Tatsuya; Miyagi, Yuhichi; Terada, Kazuya; Ohta, Akira

    2013-07-01

    Pulmonary artery sling is frequently combined with tracheal stenosis, and occasionally combined with congenital heart defects. However, there are few reports of successfully treated cases that were combined with single ventricle. In this article, we report a successfully treated case of pulmonary artery sling combined with tracheal stenosis, single ventricle, pulmonary atresia, vascular ring, and bilateral superior vena cava. A male infant was referred to our hospital for central cyanosis, and was diagnosed with single ventricle (tricuspid stenosis, multiple ventricular septal defect, and hypoplastic right ventricle)with pulmonary atresia by echocardiogram. Tracheal stenosis was shown at cardiac catheterization. Pulmonary artery sling and tracheal diverticulum were diagnosed by computed tomography (CT) and magnetic resonance imaging(MRI)examination. Furthermore, the patient was complicated by vascular ring, which consisted of right aortic arch, an aberrant left subclavian artery, and patent ductus arteriosus, and this ductus arteriosus was connected to the left subclavian artery and pulmonary arterial trunk. After 6 months of medical treatment, including continuous infusion of prostaglandin, re-evaluation was performed by cardiac catheterization. We considered that bidirectional cavo-pulmonary shunt was appropriate for the patient since his pulmonary vasculature had matured well. An operation was performed under the use of cardio-pulmonary bypass. Release of vascular ring by division of the ductus, bilateral bidirectional cavo-pulmonary shunt, and a slide tracheoplasty for tracheal stenosis were performed simultaneously. His recovery was uneventful, and he is currently waiting to receive a Fontan-type operation.

  3. Relationship Between Adaptive Morphological and Electrophysiological Remodeling of the Left Ventricle in Young Athletes After an 8-Month Period of Sports Training.

    PubMed

    Krenc, Zbigniew

    2016-02-01

    The aim of this investigation was to assess the influence of an 8-month physical training period on left ventricular voltages identified by resting ECG in relation to changes in left ventricle mass in adolescent athletes. The study encompassed 28 adolescents aged 13 years (14 boys and 14 girls) from a sports secondary school. Clinical assessment was performed on all athletes before and after 8 months of physical training. Sokolov-Lyon voltage index, Cornell voltage index, and maximum spatial QRS vector magnitude demonstrated statistically significant decline during the study period. The specific potential of the myocardium also significantly decreased during 8 months of training. The Sokolov-Lyon voltage criterion for left ventricular hypertrophy was fulfilled in 9 athletes (32.1%) at the beginning of the observation and only in 3 athletes (10.7%) at the end of the study. On the other hand, mean left ventricular mass and mean left ventricular mass index significantly increased after long-term training. No statistically significant correlations were identified between relative changes in left ventricular mass and QRS voltages. An early period of intensive physical training in young athletes is associated with a decrease in QRS amplitude and a relative voltage deficit over the left ventricle.

  4. The effect of regular physical activity on the left ventricle systolic function in patients with chronic coronary artery disease.

    PubMed

    Panovský, R; Kukla, P; Jančár, R; Meluzín, J; Jančík, J; Kincl, V; Poloková, K; Mífková, L; Havelková, A; Látalová, R; Dobšák, P; Pešl, M

    2011-01-01

    The purpose of this study was to assess the influence of aerobic training on the left ventricular (LV) systolic function. Thirty patients with stable coronary artery disease, who had participated in the conducted 3-month physical training, were retrospectively divided into 2 cohorts. While patients in the cohort I (n=14) had continued training individually for 12 months, patients in the cohort II (n=16) had stopped training after finishing the conducted program. Rest and stress dobutamine/atropine echocardiography was performed in all patients before the training program and 1 year later. The peak systolic velocities of mitral annulus (Sa) were assessed by tissue Doppler imaging for individual LV walls. In addition, to determine global LV systolic longitudinal function, the four-site mean systolic velocity was calculated (Sa glob). According to the blood supply, left ventricular walls were divided into 5 groups: A- walls supplied by nonstenotic artery; B- walls supplied by coronary artery with stenosis ≤50 %; C- walls supplied by coronary artery with stenosis 51-70 %; D- walls with stenosis of supplying artery 71-99 %; and E- walls with totally occluded supplying artery. In global systolic function, the follow-up values of Sa glob in cohort I were improved by 0.23±0.36 as compared with baseline values at rest, and by 1.26±0.65 cm/s at the maximal load, while the values of Sa glob in cohort II were diminished by 0.53±0.22 (p=NS), and by 1.25±0.45 cm/s (p<0.05), respectively. Concerning the resting regional function, the only significant difference between cohorts in follow-up changes was found in walls E: 0.37±0.60 versus -1.76±0.40 cm/s (p<0.05). At the maximal load, the significant difference was found only in walls A (0.16±0.84 versus -2.67±0.87 cm/s; p<0.05). Patients with regular 12-month physical activity improved their global left ventricle systolic function mainly due to improvement of contractility in walls supplied by a totally occluded coronary

  5. Total Mechanical Unloading Minimizes Metabolic Demand of Left Ventricle and Dramatically Reduces Infarct Size in Myocardial Infarction

    PubMed Central

    Kakino, Takamori; Arimura, Takahiro; Sakamoto, Takafumi; Nishikawa, Takuya; Sakamoto, Kazuo; Ikeda, Masataka; Kishi, Takuya; Ide, Tomomi; Sunagawa, Kenji

    2016-01-01

    Background Left ventricular assist device (LVAD) mechanically unloads the left ventricle (LV). Theoretical analysis indicates that partial LVAD support (p-LVAD), where LV remains ejecting, reduces LV preload while increases afterload resulting from the elevation of total cardiac output and mean aortic pressure, and consequently does not markedly decrease myocardial oxygen consumption (MVO2). In contrast, total LVAD support (t-LVAD), where LV no longer ejects, markedly decreases LV preload volume and afterload pressure, thereby strikingly reduces MVO2. Since an imbalance in oxygen supply and demand is the fundamental pathophysiology of myocardial infarction (MI), we hypothesized that t-LVAD minimizes MVO2 and reduces infarct size in MI. The purpose of this study was to evaluate the differential impact of the support level of LVAD on MVO2 and infarct size in a canine model of ischemia-reperfusion. Methods In 5 normal mongrel dogs, we examined the impact of LVAD on MVO2 at 3 support levels: Control (no LVAD support), p-LVAD and t-LVAD. In another 16 dogs, ischemia was induced by occluding major branches of the left anterior descending coronary artery (90 min) followed by reperfusion (300 min). We activated LVAD from the beginning of ischemia until 300 min of reperfusion, and compared the infarct size among 3 different levels of LVAD support. Results t-LVAD markedly reduced MVO2 (% reduction against Control: -56 ± 9%, p<0.01) whereas p-LVAD did less (-21 ± 14%, p<0.05). t-LVAD markedly reduced infarct size compared to p-LVAD (infarct area/area at risk: Control; 41.8 ± 6.4, p-LVAD; 29.1 ± 5.6 and t-LVAD; 5.0 ± 3.1%, p<0.01). Changes in creatine kinase-MB paralleled those in infarct size. Conclusions Total LVAD support that minimizes metabolic demand maximizes the benefit of LVAD in the treatment of acute myocardial infarction. PMID:27124411

  6. Biomechanical Evaluation of Different Fixation Methods for Mandibular Anterior Segmental Osteotomy Using Finite Element Analysis, Part One: Superior Repositioning Surgery.

    PubMed

    Kilinç, Yeliz; Erkmen, Erkan; Kurt, Ahmet

    2016-01-01

    The aim of the current study was to comparatively evaluate the mechanical behavior of 3 different fixation methods following various amounts of superior repositioning of mandibular anterior segment. In this study, 3 different rigid fixation configurations comprising double right L, double left L, or double I miniplates with monocortical screws were compared under vertical, horizontal, and oblique load conditions by means of finite element analysis. A three-dimensional finite element model of a fully dentate mandible was generated. A 3 and 5 mm superior repositioning of mandibular anterior segmental osteotomy were simulated. Three different finite element models corresponding to different fixation configurations were created for each superior repositioning. The von Mises stress values on fixation appliances and principal maximum stresses (Pmax) on bony structures were predicted by finite element analysis. The results have demonstrated that double right L configuration provides better stability with less stress fields in comparison with other fixation configurations used in this study.

  7. Solution-adaptive finite element method in computational fracture mechanics

    NASA Technical Reports Server (NTRS)

    Min, J. B.; Bass, J. M.; Spradley, L. W.

    1993-01-01

    Some recent results obtained using solution-adaptive finite element method in linear elastic two-dimensional fracture mechanics problems are presented. The focus is on the basic issue of adaptive finite element method for validating the applications of new methodology to fracture mechanics problems by computing demonstration problems and comparing the stress intensity factors to analytical results.

  8. Modular Finite Element Methods Library Version: 1.0

    SciTech Connect

    2010-06-22

    MFEM is a general, modular library for finite element methods. It provides a variety of finite element spaces and bilinear/linear forms in 2D and 3D. MFEM also includes classes for dealing with various types of meshes and their refinement.

  9. Generating Finite-Element Models Of Composite Materials

    NASA Technical Reports Server (NTRS)

    Melis, M. E.

    1993-01-01

    Program starts at micromechanical level, from simple inputs supplied by user. COMGEN, COmposite Model GENerator, is interactive FORTRAN program used to create wide variety of finite-element models of continuous-fiber composite materials at micromechanical level. Quickly generates batch or "session files" to be submitted to finite-element preprocessor and postprocessor program, PATRAN. COMGEN requires PATRAN to complete model.

  10. A computer graphics program for general finite element analyses

    NASA Technical Reports Server (NTRS)

    Thornton, E. A.; Sawyer, L. M.

    1978-01-01

    Documentation for a computer graphics program for displays from general finite element analyses is presented. A general description of display options and detailed user instructions are given. Several plots made in structural, thermal and fluid finite element analyses are included to illustrate program options. Sample data files are given to illustrate use of the program.

  11. Large Scale Finite Element Modeling Using Scalable Parallel Processing

    NASA Technical Reports Server (NTRS)

    Cwik, T.; Katz, D.; Zuffada, C.; Jamnejad, V.

    1995-01-01

    An iterative solver for use with finite element codes was developed for the Cray T3D massively parallel processor at the Jet Propulsion Laboratory. Finite element modeling is useful for simulating scattered or radiated electromagnetic fields from complex three-dimensional objects with geometry variations smaller than an electrical wavelength.

  12. Finite element meshing of ANSYS (trademark) solid models

    NASA Technical Reports Server (NTRS)

    Kelley, F. S.

    1987-01-01

    A large scale, general purpose finite element computer program, ANSYS, developed and marketed by Swanson Analysis Systems, Inc. is discussed. ANSYS was perhaps the first commercially available program to offer truly interactive finite element model generation. ANSYS's purpose is for solid modeling. This application is briefly discussed and illustrated.

  13. Finite element models and feedback control of flexible aerospace structures

    NASA Technical Reports Server (NTRS)

    Balas, M. J.

    1980-01-01

    Large flexible aerospace structures, such as the solar power satellite, are distributed parameter systems with very complex continuum descriptions. This paper investigates the use of finite element methods to produce reduced-order models and finite dimensional feedback controllers for these structures. The main results give conditions under which stable control of the finite element model will produce stable control of the actual structure.

  14. TAURUS96. 3-D Finite Element Code Postprocessor

    SciTech Connect

    Brown, B.; Hallquist, J.O.; Spelce, T.E.

    1993-11-30

    TAURUS is an interactive post-processing application supporting visualization of finite element analysis results on unstructured grids. TAURUS provides the ability to display deformed geometries and contours or fringes of a large number of derived results on meshes consisting of beam, plate, shell, and solid type finite elements. Time history plotting is also available.

  15. Finite-element analysis of a weld-penetration problem

    NASA Technical Reports Server (NTRS)

    Rogge, T. R.

    1977-01-01

    The stress concentration factor for a weld penetration defect is calculated by the finite-element method. A stress intensity factor is computed by use of the finite-element solution and the J-integral. The results are compared with experimental results.

  16. An efficient finite element solution for gear dynamics

    NASA Astrophysics Data System (ADS)

    Cooley, C. G.; Parker, R. G.; Vijayakar, S. M.

    2010-06-01

    A finite element formulation for the dynamic response of gear pairs is proposed. Following an established approach in lumped parameter gear dynamic models, the static solution is used as the excitation in a frequency domain solution of the finite element vibration model. The nonlinear finite element/contact mechanics formulation provides accurate calculation of the static solution and average mesh stiffness that are used in the dynamic simulation. The frequency domain finite element calculation of dynamic response compares well with numerically integrated (time domain) finite element dynamic results and previously published experimental results. Simulation time with the proposed formulation is two orders of magnitude lower than numerically integrated dynamic results. This formulation admits system level dynamic gearbox response, which may include multiple gear meshes, flexible shafts, rolling element bearings, housing structures, and other deformable components.

  17. The Relation of Finite Element and Finite Difference Methods

    NASA Technical Reports Server (NTRS)

    Vinokur, M.

    1976-01-01

    Finite element and finite difference methods are examined in order to bring out their relationship. It is shown that both methods use two types of discrete representations of continuous functions. They differ in that finite difference methods emphasize the discretization of independent variable, while finite element methods emphasize the discretization of dependent variable (referred to as functional approximations). An important point is that finite element methods use global piecewise functional approximations, while finite difference methods normally use local functional approximations. A general conclusion is that finite element methods are best designed to handle complex boundaries, while finite difference methods are superior for complex equations. It is also shown that finite volume difference methods possess many of the advantages attributed to finite element methods.

  18. Finite Element Simulations to Explore Assumptions in Kolsky Bar Experiments.

    SciTech Connect

    Crum, Justin

    2015-08-05

    The chief purpose of this project has been to develop a set of finite element models that attempt to explore some of the assumptions in the experimental set-up and data reduction of the Kolsky bar experiment. In brief, the Kolsky bar, sometimes referred to as the split Hopkinson pressure bar, is an experimental apparatus used to study the mechanical properties of materials at high strain rates. Kolsky bars can be constructed to conduct experiments in tension or compression, both of which are studied in this paper. The basic operation of the tension Kolsky bar is as follows: compressed air is inserted into the barrel that contains the striker; the striker accelerates towards the left and strikes the left end of the barrel producing a tensile stress wave that propogates first through the barrel and then down the incident bar, into the specimen, and finally the transmission bar. In the compression case, the striker instead travels to the right and impacts the incident bar directly. As the stress wave travels through an interface (e.g., the incident bar to specimen connection), a portion of the pulse is transmitted and the rest reflected. The incident pulse, as well as the transmitted and reflected pulses are picked up by two strain gauges installed on the incident and transmitted bars as shown. By interpreting the data acquired by these strain gauges, the stress/strain behavior of the specimen can be determined.

  19. Finite element analysis of the human mastication cycle.

    PubMed

    Commisso, Maria S; Martínez-Reina, Javier; Ojeda, Joaquín; Mayo, Juana

    2015-01-01

    The aim of this paper is to propose a biomechanical model that could serve as a tool to overcome some difficulties encountered in experimental studies of the mandible. One of these difficulties is the inaccessibility of the temporomandibular joint (TMJ) and the lateral pterygoid muscle. The focus of this model is to study the stresses in the joint and the influence of the lateral pterygoid muscle on the mandible movement. A finite element model of the mandible, including the TMJ, was built to simulate the process of unilateral mastication. Different activation patterns of the left and right pterygoid muscles were tried. The maximum stresses in the articular disc and in the whole mandible during a complete mastication cycle were reached during the instant of centric occlusion. The simulations show a great influence of the coordination of the right and left lateral pterygoid muscles on the movement of the jaw during mastication. An asynchronous activation of the lateral pterygoid muscles is needed to achieve a normal movement of the jaw during mastication.

  20. Segmentation of the left ventricle of the heart in 3-D+t MRI data using an optimized nonrigid temporal model.

    PubMed

    Lynch, Michael; Ghita, Ovidiu; Whelan, Paul F

    2008-02-01

    Modern medical imaging modalities provide large amounts of information in both the spatial and temporal domains and the incorporation of this information in a coherent algorithmic framework is a significant challenge. In this paper, we present a novel and intuitive approach to combine 3-D spatial and temporal (3-D + time) magnetic resonance imaging (MRI) data in an integrated segmentation algorithm to extract the myocardium of the left ventricle. A novel level-set segmentation process is developed that simultaneously delineates and tracks the boundaries of the left ventricle muscle. By encoding prior knowledge about cardiac temporal evolution in a parametric framework, an expectation-maximization algorithm optimally tracks the myocardial deformation over the cardiac cycle. The expectation step deforms the level-set function while the maximization step updates the prior temporal model parameters to perform the segmentation in a nonrigid sense.

  1. Nondestructive Evaluation Correlated with Finite Element Analysis

    NASA Technical Reports Server (NTRS)

    Abdul-Azid, Ali; Baaklini, George Y.

    1999-01-01

    Advanced materials are being developed for use in high-temperature gas turbine applications. For these new materials to be fully utilized, their deformation properties, their nondestructive evaluation (NDE) quality and material durability, and their creep and fatigue fracture characteristics need to be determined by suitable experiments. The experimental findings must be analyzed, characterized, modeled and translated into constitutive equations for stress analysis and life prediction. Only when these ingredients - together with the appropriate computational tools - are available, can durability analysis be performed in the design stage, long before the component is built. One of the many structural components being evaluated by the NDE group at the NASA Lewis Research Center is the flywheel system. It is being considered as an energy storage device for advanced space vehicles. Such devices offer advantages over electrochemical batteries in situations demanding high power delivery and high energy storage per unit weight. In addition, flywheels have potentially higher efficiency and longer lifetimes with proper motor-generator and rotor design. Flywheels made of fiber-reinforced polymer composite material show great promise for energy applications because of the high energy and power densities that they can achieve along with a burst failure mode that is relatively benign in comparison to those of flywheels made of metallic materials Therefore, to help improve durability and reduce structural uncertainties, we are developing a comprehensive analytical approach to predict the reliability and life of these components under these harsh loading conditions. The combination of NDE and two- and three-dimensional finite element analyses (e.g., stress analyses and fracture mechanics) is expected to set a standardized procedure to accurately assess the applicability of using various composite materials to design a suitable rotor/flywheel assembly.

  2. Finite element simulation of thick sheet thermoforming

    NASA Astrophysics Data System (ADS)

    Mercier, Daniel

    This PhD was organized as collaboration between Lehigh University and the Ecole des Mines d'Albi on the subject: "Numerical simulation of thick sheet thermoforming". The research applications cover a wide range of products from thermoforming, e.g., packaging, automobile parts, appliance parts, large-scale panels and covers. Due to the special nature of this PhD, and the requirements of each hosting institutes, the research was split accordingly into two parts: At Lehigh University, under the supervision of Prof. Herman F. Nied, a full three-dimensional finite element program was developed in order to simulate the mechanical deformation during the process of thermoforming. The material behavior is considered hyperelastic with the property of incompressibility. The deformed structure may exhibit symmetries and may use a large choice of boundary conditions. A contact procedure for molds and/or displacements caused by a plug was implemented to complete the similarity with the thermoforming process. The research focused on simulating the observed nonlinear behaviors and their instabilities. The author emphasized the impact of large deformation on the numerical results and demonstrated the need for a remeshing capability. At the Ecole des Mines d'Albi, under the supervision of Prof. Fabrice Schmidt, an equi-biaxial rheometer was developed and built in order to determine the material properties during the process of thermoforming. Thermoplastic materials consist of long macromolecular chains that when stretched, during the process of sheet extrusion, exhibit a transversal isotropic behavior. The rheometer technique is the inflation of a circular membrane made of extruded thermoplastics. The resulting strain is identified by video analysis during the membrane inflation. This dissertation focused on technical issues related to heating with the goal of overcoming the difficulty of producing a homogeneous temperature distribution.

  3. Finite Element analyses of soil bioengineered slopes

    NASA Astrophysics Data System (ADS)

    Tamagnini, Roberto; Switala, Barbara Maria; Sudan Acharya, Madhu; Wu, Wei; Graf, Frank; Auer, Michael; te Kamp, Lothar

    2014-05-01

    Soil Bioengineering methods are not only effective from an economical point of view, but they are also interesting as fully ecological solutions. The presented project is aimed to define a numerical model which includes the impact of vegetation on slope stability, considering both mechanical and hydrological effects. In this project, a constitutive model has been developed that accounts for the multi-phase nature of the soil, namely the partly saturated condition and it also includes the effects of a biological component. The constitutive equation is implemented in the Finite Element (FE) software Comes-Geo with an implicit integration scheme that accounts for the collapse of the soils structure due to wetting. The mathematical formulation of the constitutive equations is introduced by means of thermodynamics and it simulates the growth of the biological system during the time. The numerical code is then applied in the analysis of an ideal rainfall induced landslide. The slope is analyzed for vegetated and non-vegetated conditions. The final results allow to quantitatively assessing the impact of vegetation on slope stability. This allows drawing conclusions and choosing whenever it is worthful to use soil bioengineering methods in slope stabilization instead of traditional approaches. The application of the FE methods show some advantages with respect to the commonly used limit equilibrium analyses, because it can account for the real coupled strain-diffusion nature of the problem. The mechanical strength of roots is in fact influenced by the stress evolution into the slope. Moreover, FE method does not need a pre-definition of any failure surface. FE method can also be used in monitoring the progressive failure of the soil bio-engineered system as it calculates the amount of displacements and strains of the model slope. The preliminary study results show that the formulated equations can be useful for analysis and evaluation of different soil bio

  4. Finite Element Analysis of a Floating Microstimulator

    PubMed Central

    Sahin, Mesut; Ur-Rahman, Syed S.

    2011-01-01

    Analytical solutions for voltage fields in a volume conductor are available only for ideal electrodes with radially symmetric contacts and infinitely extending substrates. Practical electrodes for neural stimulation may have asymmetric contacts and finite substrate dimensions and hence deviate from the ideal geometries. For instance, it needs to be determined if the analytical solutions are adequate for simulations of narrow shank electrodes where the substrate width is comparable to the size of the contacts. As an extension to this problem, a “floating” stimulator can be envisioned where the substrate would be finite in all directions. The question then becomes how small this floating stimulator can be made before its stimulation strength is compromised by the decrease in the medium impedance between the contacts as the contacts are approaching each other. We used finite element modeling to solve the voltage and current profiles generated by these radially asymmetric electrode geometries in a volume conductor. The simulation results suggest that both the substrate size and the bipolar contact separation influence the voltage field when these parameters are as small as a few times the contact size. Both of these effects are larger for increasing elevations from the contact surface, and even stronger for floating electrodes (finite substrate in all directions) than the shank-type electrodes. Location of the contacts on the floating electrode also plays a role in determining the voltage field. The voltage field for any device size and current, and any specific resistance of the volume conductor can be predicted from these results so long as the aspect ratios are preserved. PMID:17601192

  5. Transient outward potassium current, ‘Ito’, phenotypes in the mammalian left ventricle: underlying molecular, cellular and biophysical mechanisms

    PubMed Central

    Patel, Sangita P; Campbell, Donald L

    2005-01-01

    At least two functionally distinct transient outward K+ current (Ito) phenotypes can exist across the free wall of the left ventricle (LV). Based upon their voltage-dependent kinetics of recovery from inactivation, these two phenotypes are designated ‘Ito,fast’ (recovery time constants on the order of tens of milliseconds) and ‘Ito,slow’ (recovery time constants on the order of thousands of milliseconds). Depending upon species, either Ito,fast, Ito,slow or both current phenotypes may be expressed in the LV free wall. The expression gradients of these two Ito phenotypes across the LV free wall are typically heterogeneous and, depending upon species, may consist of functional phenotypic gradients of both Ito,fast and Ito,slow and/or density gradients of either phenotype. We review the present evidence (molecular, biophysical, electrophysiological and pharmacological) for Kv4.2/4.3 α subunits underlying LV Ito,fast and Kv1.4 α subunits underlying LV Ito,slow and speculate upon the potential roles of each of these currents in determining frequency-dependent action potential characteristics of LV subepicardial versus subendocardial myocytes in different species. We also review the possible functional implications of (i) ancillary subunits that regulate Kv1.4 and Kv4.2/4.3 (Kvβ subunits, DPPs), (ii) KChIP2 isoforms, (iii) spider toxin-mediated block of Kv4.2/4.3 (Heteropoda toxins, phrixotoxins), and (iv) potential mechanisms of modulation of Ito,fast and Ito,slow by cellular redox state, [Ca2+]i and kinase-mediated phosphorylation. Ito phenotypic activation and state-dependent gating models and molecular structure–function relationships are also discussed. PMID:15831535

  6. Evaluation of state-of-the-art segmentation algorithms for left ventricle infarct from late Gadolinium enhancement MR images.

    PubMed

    Karim, Rashed; Bhagirath, Pranav; Claus, Piet; James Housden, R; Chen, Zhong; Karimaghaloo, Zahra; Sohn, Hyon-Mok; Lara Rodríguez, Laura; Vera, Sergio; Albà, Xènia; Hennemuth, Anja; Peitgen, Heinz-Otto; Arbel, Tal; Gonzàlez Ballester, Miguel A; Frangi, Alejandro F; Götte, Marco; Razavi, Reza; Schaeffter, Tobias; Rhode, Kawal

    2016-05-01

    Studies have demonstrated the feasibility of late Gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) imaging for guiding the management of patients with sequelae to myocardial infarction, such as ventricular tachycardia and heart failure. Clinical implementation of these developments necessitates a reproducible and reliable segmentation of the infarcted regions. It is challenging to compare new algorithms for infarct segmentation in the left ventricle (LV) with existing algorithms. Benchmarking datasets with evaluation strategies are much needed to facilitate comparison. This manuscript presents a benchmarking evaluation framework for future algorithms that segment infarct from LGE CMR of the LV. The image database consists of 30 LGE CMR images of both humans and pigs that were acquired from two separate imaging centres. A consensus ground truth was obtained for all data using maximum likelihood estimation. Six widely-used fixed-thresholding methods and five recently developed algorithms are tested on the benchmarking framework. Results demonstrate that the algorithms have better overlap with the consensus ground truth than most of the n-SD fixed-thresholding methods, with the exception of the Full-Width-at-Half-Maximum (FWHM) fixed-thresholding method. Some of the pitfalls of fixed thresholding methods are demonstrated in this work. The benchmarking evaluation framework, which is a contribution of this work, can be used to test and benchmark future algorithms that detect and quantify infarct in LGE CMR images of the LV. The datasets, ground truth and evaluation code have been made publicly available through the website: https://www.cardiacatlas.org/web/guest/challenges. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  7. [Clinical functional assessment of electric cardiac instability in diastolic dysfunction of the left ventricle in patients with coronary heart disease].

    PubMed

    Tatarchenko, I P; Pozdniakova, N V; Morozova, O I; Petrushin, I A; Solov'eva, K V

    2011-01-01

    To study parameters characterizing electric myocardial unstability in coronary heart disease (CHD) patients with different variants of diastolic dysfunction (DD) of the left ventricle (LV). The study included 86 outpatients (26 females, 60 males, mean age 57.3 +/- 5.6 years) who had myocardial infarction (MI) more than 1 year before the trial with stable course of CHD during a previous month, LV ejection fraction more than 45% and with a stable sinus rhythm. Group 1 consisted of 36 patients with abnormal LV relaxation, group 2--of 28 patients with pseudo-normal LV DD, group 3--22 patients with a restrictive type of LV DD. The following examinations were made: Holter ECG monitoring, echocardiography, signal-average ECG with isolation of late ventricular potentials (LVP), estimation of heart rate variability, ventricular repolarization (Q-T interval dispersion, corrected interval Q-T). The following variants of LV DD were detected: type 1--42%, type 2--32.5%, type 3--25.5%. LV DD progression was accompanied with enhancing vegetative imbalance and sympathetic activity: in the group with abnormal relaxation--in 52.5% patients, in the group with a restrictive type--in 93.3%. CHD patients with restrictive DD had more frequent LVP (chi-square = 4.1; p < 0.05) and visualization of anomalous contractility zones (60%), ventricular extrasystole (VE) was registered in 100% cases (VE of grade IV-V in 43.3%), QT(c) and QT(d) were higher than threshold--450.2 +/- 5.4 and 71.2 +/- 6.5 ms. Because of multifactorial genesis of electric unstability, perfection of diagnosis and prognosis of risk in CHD patients with aggravation of LV DD demands a complex analysis of parameters respecting functional condition of the myocardium, relations between electric and structural-geometric remodeling of the heart.

  8. Temporal differences in ejection between right and left ventricles in chronic pulmonary hypertension: a pulsed Doppler study.

    PubMed

    López-Candales, Angel; Shaver, James; Edelman, Kathy; Candales, Maria Dolores

    2012-12-01

    Chronic pulmonary hypertension (cPH) is known to alter right ventricular (RV) deformation and cause mechanical dyssynchrony. Since not all echocardiographic laboratories are equipped with sophisticated imaging tools, we decided to determine if Doppler would be useful to detect temporal differences between the ejection of the right and left ventricle (LV) as a result of cPH using pulsed outflow tract (RVOT and LVOT) spectral signals. Data was collected from 30 patients without PH (Group I: 53 ± 7 years and 31 ± 5 mmHg) and from 40 patients with cPH (Group II: 53 ± 13 years; P = NS and 82 ± 24 mmHg; P < 0.00001). Group II patients had a longer temporal delay from onset between RVOT and LVOT (23 ± 12 ms vs. 0 ± 0 ms; P < 0.0001) with a significantly shorter temporal difference between RVOT and LVOT spectral signals to reach maximum peak of ejection (27 ± 24 ms vs. 61 ± 23 ms; P < 0.0001) than Group I. In addition, Group II had a statistically lower RVOT VTI value (0.14 ± 0.05 cm vs. 0.17 ± 0.03 cm; P < 0.01). Our data seems to suggest that increasing severity of PH mainly affects ejection of the RV resulting in noticeable temporal alterations in both time of onset as well as time to reach maximum peak ejection between RV and LV. More studies are now required to determine the utility of obtaining these measurements prospectively in the follow-up and treatment of cPH patients.

  9. Detection of differentially methylated gene promoters in failing and nonfailing human left ventricle myocardium using computation analysis

    PubMed Central

    Koczor, Christopher A.; Lee, Eva K.; Torres, Rebecca A.; Boyd, Amy; Vega, J. David; Uppal, Karan; Yuan, Fan; Fields, Earl J.; Samarel, Allen M.

    2013-01-01

    Human dilated cardiomyopathy (DCM) is characterized by congestive heart failure and altered myocardial gene expression. Epigenetic changes, including DNA methylation, are implicated in the development of DCM but have not been studied extensively. Clinical human DCM and nonfailing control left ventricle samples were individually analyzed for DNA methylation and expressional changes. Expression microarrays were used to identify 393 overexpressed and 349 underexpressed genes in DCM (GEO accession number: GSE43435). Gene promoter microarrays were utilized for DNA methylation analysis, and the resulting data were analyzed by two different computational methods. In the first method, we utilized subtractive analysis of DNA methylation peak data to identify 158 gene promoters exhibiting DNA methylation changes that correlated with expression changes. In the second method, a two-stage approach combined a particle swarm optimization feature selection algorithm and a discriminant analysis via mixed integer programming classifier to identify differentially methylated gene promoters. This analysis identified 51 hypermethylated promoters and six hypomethylated promoters in DCM with 100% cross-validation accuracy in the group assignment. Generation of a composite list of genes identified by subtractive analysis and two-stage computation analysis revealed four genes that exhibited differential DNA methylation by both methods in addition to altered gene expression. Computationally identified genes (AURKB, BTNL9, CLDN5, and TK1) define a central set of differentially methylated gene promoters that are important in classifying DCM. These genes have no previously reported role in DCM. This study documents that rigorous computational analysis applied to microarray analysis of healthy and diseased human heart samples helps to define clinically relevant DNA methylation and expressional changes in DCM. PMID:23695888

  10. Detection of differentially methylated gene promoters in failing and nonfailing human left ventricle myocardium using computation analysis.

    PubMed

    Koczor, Christopher A; Lee, Eva K; Torres, Rebecca A; Boyd, Amy; Vega, J David; Uppal, Karan; Yuan, Fan; Fields, Earl J; Samarel, Allen M; Lewis, William

    2013-07-15

    Human dilated cardiomyopathy (DCM) is characterized by congestive heart failure and altered myocardial gene expression. Epigenetic changes, including DNA methylation, are implicated in the development of DCM but have not been studied extensively. Clinical human DCM and nonfailing control left ventricle samples were individually analyzed for DNA methylation and expressional changes. Expression microarrays were used to identify 393 overexpressed and 349 underexpressed genes in DCM (GEO accession number: GSE43435). Gene promoter microarrays were utilized for DNA methylation analysis, and the resulting data were analyzed by two different computational methods. In the first method, we utilized subtractive analysis of DNA methylation peak data to identify 158 gene promoters exhibiting DNA methylation changes that correlated with expression changes. In the second method, a two-stage approach combined a particle swarm optimization feature selection algorithm and a discriminant analysis via mixed integer programming classifier to identify differentially methylated gene promoters. This analysis identified 51 hypermethylated promoters and six hypomethylated promoters in DCM with 100% cross-validation accuracy in the group assignment. Generation of a composite list of genes identified by subtractive analysis and two-stage computation analysis revealed four genes that exhibited differential DNA methylation by both methods in addition to altered gene expression. Computationally identified genes (AURKB, BTNL9, CLDN5, and TK1) define a central set of differentially methylated gene promoters that are important in classifying DCM. These genes have no previously reported role in DCM. This study documents that rigorous computational analysis applied to microarray analysis of healthy and diseased human heart samples helps to define clinically relevant DNA methylation and expressional changes in DCM.

  11. Association between Latest Activated Sites in the Left Ventricle and Akinetic Segments in Patients with Ischemic Cardiomyopathy

    PubMed Central

    Sadeghian, Hakimeh; Kousari, Aliasghar; Majidi, Shahla; Rezvanfard, Mehrnaz; Kazemisaeid, Ali; Moezzi, Seyed Ali; Vasheghani Farahani, Ali; Abdar Esfahani, Morteza; Sahebjam, Mohammad; Zoroufian, Arezoo; Sadeghian, Afsaneh

    2016-01-01

    Background: It is not clear whether the latest activation sites in the left ventricle (LV) are matched with infracted regions in patients with ischemic cardiomyopathy (ICM). We aimed to investigate whether the latest activation sites in the LV are in agreement with the region of akinesia in patients with ICM. Methods: Data were analyzed in 106 patients (age = 60.5 ± 12.1 y, male = 88.7%) with ICM (ejection fraction ≤ 35%) who were refractory to pharmacological therapy and were referred to the echocardiography department for an evaluation of the feasibility of cardiac resynchronization therapy. Wall motion abnormalities, time to peak systolic myocardial velocity (Ts) of 6 basal and 6 mid-portion segments of the LV, and 4 frequently used dyssynchrony indices were measured using 2-dimensional echocardiography and tissue Doppler imaging (TDI). To evaluate the influence of the electrocardiographic pattern, we categorized the patients into 2 groups: patients with QRS ≤ 120 ms and those with QRS >120 ms. Results: A total of 1 272 segments were studied. The latest activation sites (with longest Ts) were most frequently located in the mid-anterior (n = 32, 30.2%) and basal-anterior segments (n = 29, 27.4%), while the most common sites of akinesia were the mid-anteroseptal (n = 65, 61.3%) and mid-septal (n = 51, 48.1%) segments. Generally, no significant concordance was found between the latest activated segments and akinesia either in all the patients or in the QRS groups. Detailed analysis within the segments indicated a good agreement between akinesia and delayed activation in the basal-lateral segment solely in the patients with QRS duration ≤ 120 ms (Φ = 0.707; p value ≤ 0.001). Conclusion: The akinetic segment on 2-dimensional echocardiogram was not matched with the latest activation sites in the LV determined by TDI in patients with ICM. PMID:27956911

  12. Association between Latest Activated Sites in the Left Ventricle and Akinetic Segments in Patients with Ischemic Cardiomyopathy.

    PubMed

    Sadeghian, Hakimeh; Kousari, Aliasghar; Majidi, Shahla; Rezvanfard, Mehrnaz; Kazemisaeid, Ali; Moezzi, Sey