594 results match your criteria Electrical Alternans

Pericardial tamponade: A comprehensive emergency medicine and echocardiography review.

Am J Emerg Med 2022 May 6;58:159-174. Epub 2022 May 6.

Department of Emergency Medicine, UHS Southern California Medical Education Consortium, Temecula, CA 92592, USA.

Introduction: Pericardial tamponade requires timely diagnosis and management. It carries a high mortality rate.

Objective: This review incorporates available evidence to clarify misconceptions regarding the clinical presentation, while provifing an in-depth expert guide on bedside echocardiography. Read More

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Transient electrical alternans in a patient with sinus tachycardia attributed to orphenadrine citrate ingestion.

Emerg Med Australas 2022 May 31. Epub 2022 May 31.

Department of Emergency Medicine, Wellington Regional Hospital, Wellington, New Zealand.

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Clinically Ambiguous Hemorrhagic Cardiac Tamponade Associated with Apixaban.

Cureus 2022 Apr 19;14(4):e24290. Epub 2022 Apr 19.

Mount Sinai Heart, Icahn School of Medicine at Mount Sinai, New York, USA.

Hemorrhagic cardiac tamponade in the setting of direct oral anticoagulants (DOACs) is rare but life-threatening. Presentation in subacute cases can also be nonspecific, which can potentially delay diagnosis. A 60-year-old female with a history of heart failure and chronic obstructive pulmonary disease presented with shortness of breath, chest pain, and cough while on treatment with apixaban after a recent hospitalization for pulmonary embolism. Read More

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Optogenetic manipulation of cardiac electrical dynamics using sub-threshold illumination: dissecting the role of cardiac alternans in terminating rapid rhythms.

Basic Res Cardiol 2022 04 29;117(1):25. Epub 2022 Apr 29.

European Laboratory for Non-Linear Spectroscopy - LENS, Sesto Fiorentino, Italy.

Cardiac action potential (AP) shape and propagation are regulated by several key dynamic factors such as ion channel recovery and intracellular Ca cycling. Experimental methods for manipulating AP electrical dynamics commonly use ion channel inhibitors that lack spatial and temporal specificity. In this work, we propose an approach based on optogenetics to manipulate cardiac electrical activity employing a light-modulated depolarizing current with intensities that are too low to elicit APs (sub-threshold illumination), but are sufficient to fine-tune AP electrical dynamics. Read More

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Multifactorial Benefits of Chronic Vagus Nerve Stimulation on Autonomic Function and Cardiac Electrical Stability in Heart Failure Patients With Reduced Ejection Fraction.

Front Physiol 2022 30;13:855756. Epub 2022 Mar 30.

LivaNova USA, Inc., Houston, TX, United States.

Heart failure with reduced left ventricular ejection fraction is a progressive disease that claims > 352,000 lives annually in the United States alone. Despite the development of an extensive array of pharmacologic and device therapies, prognosis remains poor. Disruption in autonomic balance in the form of heightened sympathetic nerve activity and reduced vagal tone have been established as major causes of heart failure progression. Read More

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MCC950 ameliorates ventricular arrhythmia vulnerability induced by heart failure.

Bioengineered 2022 04;13(4):8593-8604

Department of Cardiology, Fifth People's Hospital of Chengdu, Chengdu, PR China.

MCC950, a specific NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inhibitor, has been reported to play a role in various cardiovascular diseases. However, its role in heart failure (HF)-induced ventricular arrhythmias (VAs) remains unclear. Hence, the present study aimed to clarify the role and underlying mechanisms of MCC950 in HF-induced VAs. Read More

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Electrophysiology and Arrhythmogenesis in the Human Right Ventricular Outflow Tract.

Circ Arrhythm Electrophysiol 2022 Mar 3;15(3):e010630. Epub 2022 Mar 3.

Department of Biomedical Engineering, George Washington University, Washington, DC (K.A., A.G., N.R.F., J.B., K.G., I.R.E.).

Background: Right ventricular outflow tract (RVOT) is a common source of ventricular tachycardia, which often requires ablation. However, the mechanisms underlying the RVOT's unique arrhythmia susceptibility remain poorly understood due to lack of detailed electrophysiological and molecular studies of the human RVOT.

Methods: We conducted optical mapping studies in 16 nondiseased donor human RVOT preparations subjected to pharmacologically induced adrenergic and cholinergic stimulation to evaluate susceptibility to arrhythmias and characterize arrhythmia dynamics. Read More

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Primary Lung Adenocarcinoma Presenting as Cardiac Tamponade in a 40-Year-Old Non-Smoker.

Cureus 2022 Jan 26;14(1):e21631. Epub 2022 Jan 26.

Internal Medicine, Wellstar Atlanta Medical Center, Atlanta, USA.

Lung cancer is the number one cause of cancer-death in the world with the majority of cases directly attributable to smoking. The diagnosis is mostly made following evaluation for either an incidental lung nodule or respiratory signs and symptoms such as cough and hemoptysis. This is a review of a young never-smoker who presented predominantly with gastrointestinal symptoms, which is an uncommon initial presentation of lung cancer associated with malignant pericardial effusion. Read More

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January 2022

Apparent Atrial Dissociation and Electrical Alternans.

Laszlo Littmann

JAMA Intern Med 2022 04;182(4):438-439

Department of Internal Medicine, Atrium Health-Carolinas Medical Center Charlotte, Charlotte, North Carolina.

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Prolonged ST segment and T-wave alternans with torsade de pointes secondary to hypocalcemia due to hypoparathyroidism: A case report.

Ann Noninvasive Electrocardiol 2022 Feb 11:e12939. Epub 2022 Feb 11.

Department of Cardiology, Qinghai Provincial People's Hospital, Xining, China.

Hypoparathyroidism predisposes patients to hypocalcemia. Patients with hypoparathyroidism are thus at risk of electrocardiographic abnormalities, including T-wave alternans. T-wave alternans is poorly understood and lacks uniform diagnostic criteria. Read More

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February 2022

Voltage-mediated mechanism for calcium wave synchronization and arrhythmogenesis in atrial tissue.

Biophys J 2022 02 27;121(3):383-395. Epub 2021 Dec 27.

Department of Physics and Astronomy, California State University, Northridge, California. Electronic address:

A wide range of atrial arrythmias are caused by molecular defects in proteins that regulate calcium (Ca) cycling. In many cases, these defects promote the propagation of subcellular Ca waves in the cell, which can perturb the voltage time course and induce dangerous perturbations of the action potential (AP). However, subcellular Ca waves occur randomly in cells and, therefore, electrical coupling between cells substantially decreases their effect on the AP. Read More

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February 2022

Advances in Cardiac Pacing: Arrhythmia Prediction, Prevention and Control Strategies.

Front Physiol 2021 2;12:783241. Epub 2021 Dec 2.

IHU LIRYC, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Bordeaux, France.

Cardiac arrhythmias constitute a tremendous burden on healthcare and are the leading cause of mortality worldwide. An alarming number of people have been reported to manifest sudden cardiac death as the first symptom of cardiac arrhythmias, accounting for about 20% of all deaths annually. Furthermore, patients prone to atrial tachyarrhythmias such as atrial flutter and fibrillation often have associated comorbidities including hypertension, ischemic heart disease, valvular cardiomyopathy and increased risk of stroke. Read More

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December 2021

Electrical alternans detected by an Apple Watch.

Eur Heart J 2022 May;43(18):1775

Hospital Clinico Universitario San Carlos, Madrid 28010, Spain.

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Electrophysiological Consequences of Cardiac Fibrosis.

Cells 2021 11 18;10(11). Epub 2021 Nov 18.

Department of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, 6200 MD Maastricht, The Netherlands.

For both the atria and ventricles, fibrosis is generally recognized as one of the key determinants of conduction disturbances. By definition, fibrosis refers to an increased amount of fibrous tissue. However, fibrosis is not a singular entity. Read More

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November 2021

Controllability and state feedback control of a cardiac ionic cell model.

Comput Biol Med 2021 12 30;139:104909. Epub 2021 Sep 30.

School of Mathematical Sciences, Rochester Institute of Technology, Rochester, NY, 14623, USA. Electronic address:

A phenomenon called alternans, which is a beat-to-beat alternation in action potential (AP) duration, sometimes precedes fatal cardiac arrhythmias. Alternans-suppressing electrical stimulus protocols are often represented as perturbations to the dynamics of membrane potential or AP duration variables in nonlinear models of cardiac tissue. Controllability analysis has occasionally been applied to cardiac AP models to determine whether different control or perturbation strategies are capable of suppressing alternans or other unwanted behavior. Read More

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December 2021

A Digital Electrocardiographic System for Assessing Myocardial Electrical Instability: Principles and Applications.

Sovrem Tekhnologii Med 2021 28;12(6):15-19. Epub 2020 Dec 28.

Professor, Head of the Laboratory of Medical Information Technologies Republican Scientific and Practical Center "Cardiology", Ministry of Health of the Republic of Belarus, 110B Rosa Luxemburg St., Minsk, 220036, Republic of Belarus.

was to develop an ECG hardware and software system for monitoring electrical instability of the myocardium and to assess the diagnostic and prognostic capabilities of this setup in a cardiology clinic.

Materials And Methods: The Intecard 7.3 software and hardware system developed in this study makes it possible to measure fluctuations of the ECG amplitude-time parameters using the beat-to-beat mode. Read More

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Cardiac Alternans Occurs through the Synergy of Voltage- and Calcium-Dependent Mechanisms.

Membranes (Basel) 2021 Oct 18;11(10). Epub 2021 Oct 18.

Krasnow Institute for Advanced Study and School of Systems Biology, George Mason University, Fairfax, VA 22030, USA.

Cardiac alternans is characterized by alternating weak and strong beats of the heart. This signaling at the cellular level may appear as alternating long and short action potentials (APs) that occur in synchrony with alternating large and small calcium transients, respectively. Previous studies have suggested that alternans manifests itself through either a voltage dependent mechanism based upon action potential restitution or as a calcium dependent mechanism based on refractoriness of calcium release. Read More

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October 2021

Spectrum of clinical applications of interlead ECG heterogeneity assessment: From myocardial ischemia detection to sudden cardiac death risk stratification.

Ann Noninvasive Electrocardiol 2021 11 30;26(6):e12894. Epub 2021 Sep 30.

Division of Cardiovascular Medicine, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA.

Heterogeneity in depolarization and repolarization among regions of cardiac cells has long been recognized as a major factor in cardiac arrhythmogenesis. This fundamental principle has motivated development of noninvasive techniques for quantification of heterogeneity using the surface electrocardiogram (ECG). The initial approaches focused on interval analysis such as interlead QT dispersion and T -T difference. Read More

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November 2021

Right predominant electrical remodeling in a pure model of pulmonary hypertension promotes reentrant arrhythmias.

Heart Rhythm 2022 01 23;19(1):113-124. Epub 2021 Sep 23.

Electro-Biology and Arrhythmia Therapeutics Laboratory, Cardiovascular Research Center, Yale University, New Haven, Connecticut. Electronic address:

Background: Electrophysiological (EP) properties have been studied mainly in the monocrotaline model of pulmonary arterial hypertension (PAH). Findings are confounded by major extrapulmonary toxicities, which preclude the ability to draw definitive conclusions regarding the role of PAH per se in EP remodeling.

Objective: The purpose of this study was to investigate the EP substrate and arrhythmic vulnerability of a new model of PAH that avoids extracardiopulmonary toxicities. Read More

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January 2022

Autonomic Modulation for Treatment of Repolarization Alternans and Refractory Ventricular Electrical Storm.

JACC Case Rep 2021 Sep 15;3(12):1438-1443. Epub 2021 Sep 15.

Division of Cardiac Electrophysiology, Virginia Commonwealth University, Richmond, Virginia, USA.

Macroscopic T-wave alternans (TWA) is a rare finding on surface electrocardiogram and has been associated with an increased risk of impending sudden cardiac death. We highlight a case of macroscopic TWA in a patient with markedly prolonged QTc interval preceding ventricular electrical storm, which was refractory to medical management. Autonomic modulation of the stellate ganglion resulted in improvement in both TWA and QTc interval. Read More

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September 2021

Microvolt T-Wave Alternans Is Modulated by Acute Low-Level Tragus Stimulation in Patients With Ischemic Cardiomyopathy and Heart Failure.

Front Physiol 2021 23;12:707724. Epub 2021 Jul 23.

Cardiovascular Research Center, Massachusetts General Hospital, Boston, MA, United States.

Microvolt T-wave alternans (TWA), an oscillation in T-wave morphology of the electrocardiogram (ECG), has been associated with increased susceptibility to ventricular tachy-arrhythmias, while vagus nerve stimulation has shown promising anti-arrhythmic effects in and animal studies. We aimed to examine the effect of non-invasive, acute low-level tragus stimulation (LLTS) on TWA in patients with ischemic cardiomyopathy and heart failure. 26 patients with ischemic cardiomyopathy (left ventricular ejection fraction <35%) and chronic stable heart failure, previously implanted with an automatic implantable cardioverter defibrillator (ICD) device with an atrial lead (dual chamber ICD or cardiac resynchronization therapy defibrillator), were enrolled in the study. Read More

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A space-fractional bidomain framework for cardiac electrophysiology: 1D alternans dynamics.

Chaos 2021 Jul;31(7):073123

Department of Engineering, Campus Bio-Medico University of Rome, 00128 Rome, Italy.

Cardiac electrophysiology modeling deals with a complex network of excitable cells forming an intricate syncytium: the heart. The electrical activity of the heart shows recurrent spatial patterns of activation, known as cardiac alternans, featuring multiscale emerging behavior. On these grounds, we propose a novel mathematical formulation for cardiac electrophysiology modeling and simulation incorporating spatially non-local couplings within a physiological reaction-diffusion scenario. Read More

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Epileptic heart: A clinical syndromic approach.

Epilepsia 2021 08 8;62(8):1780-1789. Epub 2021 Jul 8.

Department of Neurology, Harvard Medical School, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA.

Prevention of premature death in patients with chronic epilepsy remains a major challenge. Multiple pathophysiologic factors have been implicated, with intense investigation of cardiorespiratory mechanisms. Up to four in five patients with chronic epilepsy exhibit cardiovascular comorbidities. Read More

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Data-driven phase-isostable reduction for optimal nonfeedback stabilization of cardiac alternans.

Phys Rev E 2021 May;103(5-1):052203

Department of Electrical Engineering and Computer Science, University of Tennessee, Knoxville, Tennessee 37996, USA.

Phase-isostable reduction is an emerging model reduction strategy that can be used to accurately replicate nonlinear behaviors in systems for which standard phase reduction techniques fail. In this work, we derive relationships between the cycle-to-cycle variance of the reduced isostable coordinates for systems subject to both additive white noise and periodic stimulation. Using this information, we propose a data-driven technique for inferring nonlinear terms of the phase-isostable coordinate reduction framework. Read More

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Low-Level Tragus Stimulation Modulates Atrial Alternans and Fibrillation Burden in Patients With Paroxysmal Atrial Fibrillation.

J Am Heart Assoc 2021 06 2;10(12):e020865. Epub 2021 Jun 2.

Cardiovascular Research Center Massachusetts General Hospital Boston MA.

Background Low-level tragus stimulation (LLTS) has been shown to significantly reduce atrial fibrillation (AF) burden in patients with paroxysmal AF. P-wave alternans (PWA) is believed to be generated by the same substrate responsible for AF. Hence, PWA may serve as a marker in guiding LLTS therapy. Read More

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Clinical Potential of Beat-to-Beat Diastolic Interval Control in Preventing Cardiac Arrhythmias.

J Am Heart Assoc 2021 06 22;10(11):e020750. Epub 2021 May 22.

Department of Biomedical Engineering University of Minnesota-Twin Cities Minneapolis MN.

Life-threatening ventricular arrhythmias and sudden cardiac death are often preceded by cardiac alternans, a beat-to-beat oscillation in the T-wave morphology or duration. However, given the spatiotemporal and structural complexity of the human heart, designing algorithms to effectively suppress alternans and prevent fatal rhythms is challenging. Recently, an antiarrhythmic constant diastolic interval pacing protocol was proposed and shown to be effective in suppressing alternans in 0-, 1-, and 2-dimensional in silico studies as well as in ex vivo whole heart experiments. Read More

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Thermal effects on cardiac alternans onset and development: A spatiotemporal correlation analysis.

Phys Rev E 2021 Apr;103(4):L040201

Department of Engineering and ICRA, Campus Bio-Medico University of Rome, 00128 Rome, Italy and International Center for Relativistic Astrophysics Network-ICRANet, 65122 Pescara, Italy.

Alternans of cardiac action potential duration represent critical precursors for the development of life-threatening arrhythmias and sudden cardiac death. The system's thermal state affects these electrical disorders requiring additional theoretical and experimental efforts to improve a patient-specific clinical understanding. In such a scenario, we generalize a recent work from Loppini et al. Read More

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Electrical Alternans in a Patient With Acute Bronchial Asthma Exacerbation.

Am J Med Sci 2021 11 8;362(5):e45-e46. Epub 2021 May 8.

Division of Urology, Department of Surgery, Children's Hospital of Eastern Ontario, Ontario, Canada.

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November 2021

Controllability of voltage- and calcium-driven cardiac alternans in a map model.

Chaos 2021 Feb;31(2):023139

School of Computational Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-4017, USA.

Certain cardiac arrhythmias are preceded by electrical alternans, a state characterized by beat-to-beat alternation in cellular action potential duration. Cardiac alternans may arise from different mechanisms including instabilities in voltage or intracellular calcium cycling. Although a number of techniques have been proposed to suppress alternans, these methods have mainly been tested using models that do not support calcium-driven alternans. Read More

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February 2021