scholarly journals Anisotropic Elastography for Local Passive Properties and Active Contractility of Myocardium from Dynamic Heart Imaging Sequence

2006 ◽  
Vol 2006 ◽  
pp. 1-15 ◽  
Author(s):  
Yi Liu ◽  
Ge Wang ◽  
L. Z. Sun
Keyword(s):  
Mechanical Properties ◽  
Adjoint Method ◽  
Heart Diseases ◽  
Imaging Techniques ◽  
Chamber Pressure ◽  
Cardiac Imaging Techniques ◽  
Dynamic Displacement ◽  
Material Parameters ◽  
Ischemic Region ◽  
Imaging Sequence

Major heart diseases such as ischemia and hypertrophic myocardiopathy are accompanied with significant changes in the passive mechanical properties and active contractility of myocardium. Identification of these changes helps diagnose heart diseases, monitor therapy, and design surgery. A dynamic cardiac elastography (DCE) framework is developed to assess the anisotropic viscoelastic passive properties and active contractility of myocardial tissues, based on the chamber pressure and dynamic displacement measured with cardiac imaging techniques. A dynamic adjoint method is derived to enhance the numerical efficiency and stability of DCE. Model-based simulations are conducted using a numerical left ventricle (LV) phantom with an ischemic region. The passive material parameters of normal and ischemic tissues are identified during LV rapid/reduced filling and artery contraction, and those of active contractility are quantified during isovolumetric contraction and rapid/reduced ejection. It is found that quasistatic simplification in the previous cardiac elastography studies may yield inaccurate material parameters.

scholarly journals Study of biaxial mechanical properties of the passive pig heart: material characterisation and categorisation of regional differences

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Fulufhelo Nemavhola
Keyword(s):  
Mechanical Properties ◽  
Constitutive Model ◽  
Computational Models ◽  
Heart Diseases ◽  
Interventricular Septum ◽  
Model Material ◽  
Biaxial Test ◽  
Material Behaviour ◽  
Material Parameters ◽  
Biaxial Tests

AbstractRegional mechanics of the heart is vital in the development of accurate computational models for the pursuit of relevant therapies. Challenges related to heart dysfunctioning are the most important sources of mortality in the world. For example, myocardial infarction (MI) is the foremost killer in sub-Saharan African countries. Mechanical characterisation plays an important role in achieving accurate material behaviour. Material behaviour and constitutive modelling are essential for accurate development of computational models. The biaxial test data was utilised to generated Fung constitutive model material parameters of specific region of the pig myocardium. Also, Choi-Vito constitutive model material parameters were also determined in various myocardia regions. In most cases previously, the mechanical properties of the heart myocardium were assumed to be homogeneous. Most of the computational models developed have assumed that the all three heart regions exhibit similar mechanical properties. Hence, the main objective of this paper is to determine the mechanical material properties of healthy porcine myocardium in three regions, namely left ventricle (LV), mid-wall/interventricular septum (MDW) and right ventricle (RV). The biomechanical properties of the pig heart RV, LV and MDW were characterised using biaxial testing. The biaxial tests show the pig heart myocardium behaves non-linearly, heterogeneously and anisotropically. In this study, it was shown that RV, LV and MDW may exhibit slightly different mechanical properties. Material parameters of two selected constitutive models here may be helpful in regional tissue mechanics, especially for the understanding of various heart diseases and development of new therapies.

Cardiovascular Imaging for Guiding Interventional Therapy in Structural Heart Diseases

2020 ◽  
Vol 16 (2) ◽  
pp. 111-122
Author(s):  
Nora Rat ◽  
Iolanda Muntean ◽  
Diana Opincariu ◽  
Liliana Gozar ◽  
Rodica Togănel ◽  
...  
Keyword(s):  
Heart Diseases ◽  
Interventional Procedure ◽  
Imaging Techniques ◽  
Ductus Arteriosus ◽  
Three Dimensional ◽  
High Specificity ◽  
Interventional Therapy ◽  
Structural Defects ◽  
Imaging Method ◽  
Three Dimensional Echocardiography

Development of interventional methods has revolutionized the treatment of structural cardiac diseases. Given the complexity of structural interventions and the anatomical variability of various structural defects, novel imaging techniques have been implemented in the current clinical practice for guiding the interventional procedure and for selection of the device to be used. Three– dimensional echocardiography is the most used imaging method that has improved the threedimensional assessment of cardiac structures, and it has considerably reduced the cost of complications derived from malalignment of interventional devices. Assessment of cardiac structures with the use of angiography holds the advantage of providing images in real time, but it does not allow an anatomical description. Transesophageal Echocardiography (TEE) and intracardiac ultrasonography play major roles in guiding Atrial Septal Defect (ASD) or Patent Foramen Ovale (PFO) closure and device follow-up, while TEE is the procedure of choice to assess the flow in the Left Atrial Appendage (LAA) and the embolic risk associated with a decreased flow. On the other hand, contrast CT and MRI have high specificity for providing a detailed description of structure, but cannot assess the flow through the shunt or the valvular mobility. This review aims to present the role of modern imaging techniques in pre-procedural assessment and intraprocedural guiding of structural percutaneous interventions performed to close an ASD, a PFO, an LAA or a patent ductus arteriosus.

scholarly journals Cardiotoxic effects and myocardial injury: the search for a more precise definition of drug cardiotoxicity

2021 ◽  
Vol 59 (1) ◽  
pp. 51-57
Author(s):  
Daniela Maria Cardinale ◽  
Martina Zaninotto ◽  
Carlo Maria Cipolla ◽  
Claudio Passino ◽  
Mario Plebani ◽  
...  
Keyword(s):  
Early Detection ◽  
Myocardial Injury ◽  
Randomized Clinical Trials ◽  
Imaging Techniques ◽  
Left Ventricular ◽  
Left Ventricular Ejection ◽  
Cardiac Imaging Techniques ◽  
Ventricular Ejection Fraction ◽  
Early Evaluation ◽  
Definition Of

AbstractDrug-induced cardiotoxicity is a major clinical problem; cardiotoxic drugs may induce both cardiac dysfunction and myocardial injury. Several recent studies reported that cardiac troponins measured with high-sensitivity methods (hs-cTn) can enable the early detection of myocardial injury related to chemotherapy or abuse of drugs that are potentially cardiotoxic. Several authors have some concerns about the standard definition of cardiotoxicity, in particular, regarding the early evaluation of chemotherapy cardiotoxicity in cancer patients. Several recent studies using the hs-cTn assay indicate that myocardial injury may precede by some months or years the diagnosis of heart failure (HF) based on the evaluation of left ventricular ejection fraction (LVEF). Accordingly, hs-cTn assay should considered to be a reliable laboratory test for the early detection of asymptomatic or subclinical cardiotoxic damage in patients undergoing cancer chemotherapy. In accordance with the Fourth Universal Definition of Myocardial Infarction and also taking into account the recent experimental and clinical evidences, the definition of drug-cardiotoxicity should be updated considering the early evaluation of myocardial injury by means of hs-cTn assay. It is conceivable that the combined use of hs-cTn assay and cardiac imaging techniques for the evaluation of cardiotoxicity will significantly increase both diagnostic sensitivity and specificity, and also better prevent chemotherapy-related left ventricular (LV) dysfunction and other adverse cardiac events. However, large randomized clinical trials are needed to evaluate the cost/benefit ratio of standardized protocols for the early detection of cardiotoxicity using hs-cTn assay in patients receiving chemotherapy for malignant diseases.

Abstract P391: Marine N-3 Fatty Acids Reduce Atherosclerosis Cardiovascular Disease: A Systemic Review and Meta-analysis of Clinical Trials

Circulation ◽  
2013 ◽  
Vol 127 (suppl_12) ◽  
Author(s):  
Akira Sekikawa ◽  
Nobutake Hirooka ◽  
Abhishek Vishnu ◽  
Vashudha Ahuja ◽  
Emmanuel Sampene ◽  
...  
Keyword(s):  
Cardiovascular Disease ◽  
Fatty Acids ◽  
Clinical Trials ◽  
Randomized Clinical Trials ◽  
Imaging Techniques ◽  
Meta Analysis ◽  
Quantitative Information ◽  
Systemic Review ◽  
Cochrane Library ◽  
Cardiac Imaging Techniques

Introduction: Although marine n-3 fatty acids are believed to be cardioprotective through their anti-arrhythmic, anti-thrombotic, anti-atherogenic and other effects, results from recent meta-analyses of marine n-3 fatty acids on cardiovascular disease (CVD) are controversial. We performed a meta-analysis of marine n-3 fatty acids on CVD outcomes in randomized clinical trials (RCTs) to test the hypothesis that marine n-3 fatty acids are anti-atherogenic. We also tested the hypothesis that such benefit is dose-dependent. Methods: A systematic review of English language articles using PubMed, EMBASE and Cochrane Library through Aug 2012 was performed selecting RCTs evaluating the effect of marine n-3 fatty acids intake for 2 years or more on cardiovascular diseases, coronary disease, arteriosclerosis, cardiac imaging techniques, and carotid artery ultrasound. Descriptive and quantitative information was extracted. Odds ratios were calculated for cardiac event outcome. Correlation coefficients were obtained from studies of which outcome is intima-media thickness (IMT) and coronary lumen diameter (CD). We converted the estimates into a single effect size; the log odds ratio and its corresponding standard error. Results: Of 14,236 citations retrieved, 13 studies were selected, including studies reporting IMT (n=3) and CD (n=2) and major CVD events (n=8). Overall, marine n-3 fatty acids significantly reduced atherosclerotic CVD (RR 0.94: 95%CI 0.90 to 0.99, p<0.05). There was no evidence of heterogeneity (p=0.65) or publication bias (p=0.37, Begg’s test). A sub-analysis among 8 studies of major CVD events showed the similar results (RR 0.94: 95% CI 0.89 to 0.99, p<0.05). Another sub-analysis among 4 studies excluding sudden cardiac death as an outcome showed RR of 0.91 (95% CI 0.82 to 1.02, p=0.097). A meta-regression analysis shows that dose of marine n-3 fatty acids was inversely associated with CVD outcome, although the association was not statistically significant (p=0.06). Conclusions: The result of our meta-analysis supports a modest anti-atherogenic effect of marine n-3 fatty acids. This benefit may be proportional to the amount of marine n-3 fatty acids consumed.

Magnetic Resonance Elastography for the Measurement of Annulus Fibrosus Material Properties

2011 ◽  
Author(s):  
Daniel H. Cortes ◽  
Lachlan J. Smith ◽  
Sung M. Moon ◽  
Jeremy F. Magland ◽  
Alexander C. Wright ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Magnetic Resonance ◽  
Shear Modulus ◽  
Disc Degeneration ◽  
Annulus Fibrosus ◽  
Pulse Sequence ◽  
Imaging Techniques ◽  
Mechanical Vibration ◽  
Magnetic Resonance Elastography

Intervertebral disc degeneration is characterized by a progressive cascade of structural, biochemical and biomechanical changes affecting the annulus fibrosus (AF), nucleus pulposus (NP) and end plates (EP). These changes are considered to contribute to the onset of back pain. It has been shown that mechanical properties of the AF and NP change significantly with degeneration [1,2]. Therefore, mechanical properties have the potential to serve as a biomarker for diagnosis of disc degeneration. Currently, disc degeneration is diagnosed based on the detection of structural and compositional changes using MRI, X-ray, discography and other imaging techniques. These methods, however, do not measure directly the mechanical properties of the extracellular matrix of the disc. Magnetic Resonance Elastography (MRE) is a technique that has been used to measure in vivo mechanical properties of soft tissue by applying a mechanical vibration and measuring displacements with a motion-sensitized MRI pulse sequence [3]. The mechanical properties (e.g., the shear modulus) are calculated from the displacement field using an inverse method. Since the applied displacements are in the order of few microns, fibers may not be stretched enough to remove crimping. Therefore, it is unknown if the anisotropy of the AF due to the contribution of the fibers is detectable using MRE. The objective of this study is twofold: to measure shear properties of AF in different orientations to determine the degree of AF anisotropy observable by MRE, and to identify the contribution of different AF constituents to the measured shear modulus by applying different biochemical treatments.

scholarly journals Second Wave of COVID-19 Pandemic in Malaysia and the Impact on Nuclear Cardiology Services: An Institutional Experience

2021 ◽  
Vol 5 ◽  
pp. 25
Author(s):  
Ahmad Zaid Zanial ◽  
Syifaa Aminudin ◽  
FatinHayani Mohamad Najib ◽  
Siti Zarina Amir Hassan
Keyword(s):  
Nuclear Medicine ◽  
Infection Control ◽  
Nuclear Cardiology ◽  
Heart Diseases ◽  
Imaging Techniques ◽  
Main Difficulty ◽  
Technetium 99M ◽  
Institutional Experience ◽  
The Impact ◽  
Second Wave

Introduction: Nuclear cardiology applying radioactive tracer and hybrid imaging techniques are able to provide information needed to detect and evaluate ischaemic heart diseases. In our centre, nuclear cardiology services involving stress and rest myocardial perfusion scans and viability studies contribute about 40% of overall scan workload. The second wave of COVID- 19 pandemic in Malaysia announced by the end of February 2020 has affected nuclear cardiology services.Objectives: Our aims were to determine the impact of COVID-19 pandemic second wave on the nuclear cardiology imaging studies performed as well as to ascertain crucial institutional experience especially unavoidable problem and adjustment during the period.Methods: A review of Technetium-99m tetrofosmin radiopharmaceutical dispensing data and scan records for 1st February to 31st August 2019 and 2020 was conducted at Nuclear Medicine Department, Hospital Kuala Lumpur. Figures were compiled and statistical analysis done. Survey and focus discussion conducted involving nuclear medicine physicians, pharmacists and physic officers to identify the main difficulty faced and most important Job-adapting measure taken.Results: A total of 1109 cardiac radiopharmaceutical doses dispensed during the studied period but were less when compared to 1342 doses dispensed last year. Significant reduction was noted in April and May 2020 with only 69 and 67 cases respectively in comparison with monthly average of 192 cases in 2019. Although some scan appointments were postponed to avoid the usual waiting area congestions, the main difficulty faced was Technetium-99m generator supply disruption with limited production in Europe and international transportation restriction. Implementing infection control standard operating procedure (SOP) instructions as part of routine work practice with emphasis of time, distance and shielding concept was the most important Job-adapting measure.Conclusion: Nuclear cardiology services were affected by the second wave of COVID-19 pandemic locally. Main problem ascertained was disruption of radioactive supply. Most important adjustment was infection control SOP implementation.International Journal of Human and Health Sciences Supplementary Issue: 2021 Page: S25

Determination of mechanical properties from sharp dynamic indentation

2021 ◽  
pp. 030932472110592
Author(s):  
Bowen Si ◽  
Zhiqiang Li ◽  
Gesheng Xiao ◽  
Xuefeng Shu
Keyword(s):  
Mechanical Properties ◽  
Power Law ◽  
Split Hopkinson Pressure Bar ◽  
Indentation Test ◽  
Hopkinson Pressure Bar ◽  
Dynamic Indentation ◽  
Material Parameters ◽  
Split Hopkinson ◽  
Pressure Bar ◽  
Indentation Response

In this study, a dynamic indentation test method based on the split Hopkinson pressure bar is proposed to obtain the dynamic parameters of Ludwik power law constitutive, namely, Young’s modulus E, strength coefficient K, and strain hardening index n by analyzing dynamic indentation load-indentation depth curve obtained from the theories relating to the Hopkinson pressure bar. The important parameters, namely, loading curvature C and transformation factor [Formula: see text], are invoked to examine the dynamic indentation response results in a wide range of target material parameters. Finite element calculation results are processed through simulation of dynamic indentation response with broad material parameters. Furthermore, the analytical method is used to fit simulation results to obtain the analytical equations for elastic–plastic parameters and curvature parameters for the subsequent analysis. The analytical equation of forward model to predict dynamic indentation response parameter–loading curvature C of a known material is proposed. Then, the elastic–plastic parameters of unknown materials (according to Ludwik power law) are obtained by substituting the dynamic indentation response parameters into an inverse analytical equation under the two types of half-cone angle indenters. The method is verified by other typical materials, which shows that the dynamic indentation test based on the split Hopkinson pressure bar can obtain sufficient conditions to obtain dynamic mechanical properties of target materials.

Myocarditis

2021 ◽  
pp. 715-730
Author(s):  
Ali Yilmaz ◽  
Heiko Mahrholdt ◽  
Udo Sechtem
Keyword(s):  
Cardiac Imaging ◽  
Viral Infections ◽  
Imaging Techniques ◽  
Correct Diagnosis ◽  
Left Ventricular ◽  
Cardiac Imaging Techniques ◽  
Additional Information ◽  
Large Patient ◽  
Chest X Ray ◽  
Clinical Tools

The symptoms and signs of myocarditis are non-specific. Thus, myocarditis is a differential diagnosis in many patients with heart complaints. As myocarditis may accompany common viral infections of the upper respiratory and gastrointestinal tracts, and mild ECG changes are not uncommon in such patients, the diagnosis needs to be considered in large patient cohorts. Establishing the correct diagnosis is of importance as the disease may lead to sudden cardiac death or dilated cardiomyopathy. As clinical tools such as history taking, physical examination, blood tests, the ECG, and the chest X-ray are not sufficient to ascertain the diagnosis of myocarditis, additional information from cardiac imaging techniques, or endomyocardial biopsy are necessary to confirm or exclude the disease. In daily clinical routine, however, the use of biopsy is limited to severely ill patients with reduced left ventricular function due to its invasiveness and potential complications. Thus, this chapter reviews how non-invasive cardiac imaging techniques can be used in clinical practice to diagnose myocarditis.

Cardiac resynchronization therapy: optimization and follow-up

2015 ◽  
pp. 420-431
Author(s):  
Marta Sitges ◽  
Genevieve Derumeaux
Keyword(s):  
Cardiac Resynchronization Therapy ◽  
Imaging Techniques ◽  
Biventricular Pacing ◽  
Left Ventricular ◽  
Cardiac Resynchronization ◽  
Functional Mitral Regurgitation ◽  
Cardiac Imaging Techniques ◽  
Resynchronization Therapy

Cardiac imaging techniques have an important role in the follow-up of patients undergoing cardiac resynchronization therapy (CRT) as they provide objective evidence of changes in cardiac dimensions and function. The role of echocardiography is well established in the assessment of left ventricular reverse remodelling and the evaluation of secondary (functional) mitral regurgitation. Additionally, echocardiography might be used for optimizing the programming of atrio-ventricular (AV) and inter-ventricular (VV) delays of current CRT devices. Acute benefits from this optimization have been demonstrated, but longer follow-up studies have failed to show a clear benefit of optimized CRT on top of simultaneous biventricular pacing on the outcome of patients with CRT. This chapter reviews the role of imaging in assessing follow-up and outcome of patients undergoing CRT, as well as the rationale, the methods used, and the clinical impact of optimization of the programming of CRT devices.

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