569 results match your criteria Electrical Alternans

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 Jun 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 Jun 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 May 8. Epub 2021 May 8.

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

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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

Hemopericardium with subsequent cardiac tamponade secondary to rivaroxaban treatment: a case report.

Eur Heart J Case Rep 2021 Jan 11;5(1):ytaa482. Epub 2020 Dec 11.

ProMedica Toledo Hospital, 2142 N Cove Blvd, Toledo, OH 43606, USA.

Background: The use and utility of novel oral anticoagulants has been increasing in clinical practice due to their relatively lower incidence of side effects such as intracranial haemorrhage, particularly in the elderly, when compared with vitamin K antagonists. Rivaroxaban is a factor Xa and prothrombinase inhibitor indicated for stroke and venous thromboembolism prophylaxis in non-valvular atrial fibrillation as well as treatment of venous thromboembolism.

Case Summary: A patient with history of paroxysmal atrial fibrillation on Rivaroxaban presented with generalized malaise, lightheadedness, and dizziness. Read More

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January 2021

Breathing rate and heart rate as confounding factors in measuring T wave alternans and morphological variability in ECG.

Physiol Meas 2021 02 6;42(1):015002. Epub 2021 Feb 6.

Department of Electrical & Computer Engineering, Georgia Institute of Technology, Atlanta, GA, United States of America.

Objective: High morphological variability magnitude (MVM) and microvolt T wave alternans (TWA) within an electrocardiogram (ECG) signifies increased electrical instability and risk of sudden cardiac death. However, the influence of breathing rate (BR), heart rate (HR), and signal-to-noise ratio (SNR) is unknown and may inflate measured values.

Approach: We synthesize ECGs with morphologies derived from the Physikalisch-Technische Bundesanstalt Database. Read More

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February 2021

MD1 Depletion Predisposes to Ventricular Arrhythmias in the Setting of Myocardial Infarction.

Heart Lung Circ 2021 Jun 27;30(6):869-881. Epub 2020 Nov 27.

Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China; Cardiovascular Research Institute of Wuhan University, Wuhan, China; Hubei Key Laboratory of Cardiology, Wuhan, China. Electronic address:

Background: Myeloid differentiation protein 1 (MD1) is expressed in the human heart and is a negative regulator of Toll-like receptor 4 (TLR4) signalling. MD1 exerts anti-arrhythmic effects.

Aim: The aim of this study was to determine the role of MD1 in myocardial infarction (MI)-related ventricular arrhythmias (VAs). Read More

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Vagus Nerve Stimulation Provides Multiyear Improvements in Autonomic Function and Cardiac Electrical Stability in the ANTHEM-HF Study.

J Card Fail 2021 Feb 10;27(2):208-216. Epub 2020 Oct 10.

Beth Israel Deaconess Medical Center, Division of Cardiovascular Medicine, Boston, Massachusetts; Harvard Medical School, Boston, Massachusetts. Electronic address:

Background: Patients with heart failure with reduced left ventricular ejection fraction (LVEF) (HFrEF) experience long-term deterioration of autonomic function and cardiac electrical stability linked to increased mortality risk. The Autonomic Neural Regulation Therapy to Enhance Myocardial Function in Heart Failure (ANTHEM-HF) trial reported improved heart rate variability (HRV) and heart rate turbulence (HRT) and reduced T-wave alternans (TWA) after 12 months of vagus nerve stimulation (VNS). We investigated whether the benefits of chronic VNS persist in the long term. Read More

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February 2021

Observability analysis and state observer design for a cardiac ionic cell model.

Comput Biol Med 2020 10 8;125:103910. Epub 2020 Jul 8.

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

To gain insights into cardiac arrhythmias, researchers have developed and employed various measurement techniques, such as electrocardiography, optical mapping, and patch clamping. However, there are no measurement methods that allow simultaneous recording of all cellular quantities, including intracellular ionic concentrations and gating states, that may play an important role in arrhythmia formation. To help address this shortcoming, we applied observability analysis, a method from control theory, to the Luo-Rudy dynamic (LRd) model of a cardiac ventricular myocyte. Read More

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October 2020

Dual regulation by subcellular calcium heterogeneity and heart rate variability on cardiac electromechanical dynamics.

Chaos 2020 Sep;30(9):093129

Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio 43210, USA.

Heart rate constantly varies under physiological conditions, termed heart rate variability (HRV), and in clinical studies, low HRV is associated with a greater risk of cardiac arrhythmias. Prior work has shown that HRV influences the temporal patterns of electrical activity, specifically the formation of pro-arrhythmic alternans, a beat-to-beat alternation in the action potential duration (APD), or intracellular calcium (Ca) levels. We previously showed that HRV may be anti-arrhythmic by disrupting APD and Ca alternations in a homogeneous cardiac myocyte. Read More

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September 2020

A rare case of cardiac tamponade masquerading as acute abdomen.

Int J Surg Case Rep 2020 3;77S:S121-S124. Epub 2020 Sep 3.

Department of General Surgery, Department of Applied Clinical Science and Biotechnology, University of L'Aquila, Italy.

Introduction: Acute abdomen is any acute abdominal condition requiring a quick response. The incidence varies according to age and disease aetiology. The abdominal discomfort associated with extra-abdominal pathophysiology and thoracic conditions could mimic acute abdomen. Read More

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September 2020

Atrial natriuretic peptide accelerates onset and dynamics of ventricular fibrillation during hypokalemia in isolated rabbit hearts.

J Electrocardiol 2020 Sep - Oct;62:184-189. Epub 2020 Sep 3.

Abbott, Sylmar, CA, United States of America.

Background: Atrial natriuretic peptide (ANP), which is released by the heart in response to acute cardiac stretch, possesses cardiac electrophysiological properties that include modulation of ion channel function and repolarization. However, data regarding whether ANP can directly modulate electrical instability or arrhythmias are largely lacking.

Objective: This study sought to determine whether ANP modifies onset or electrophysiological characteristics of ventricular fibrillation (VF) induced by severe hypokalemia in an isolated heart model. Read More

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Current Use and Future Needs of Noninvasive Ambulatory Electrocardiogram Monitoring.

Takanori Ikeda

Intern Med 2021 Jan 12;60(1):9-14. Epub 2020 Aug 12.

Department of Cardiovascular Medicine, Toho University Faculty of Medicine, Japan.

Remarkable progress has been seen in monitoring systems using noninvasive ambulatory electrocardiograms (ECGs). In the Holter ECG system, 12-channel formats have been utilized as diagnostic tools, particularly for the detection of transient or silent myocardial ischemia and dynamic electrical disorders. In patients diagnosed with cryptogenic stroke, despite negative results on standard ECG tests, continuous ambulatory ECG monitoring for up to 30 days has been shown to increase the detection rate of transient atrial fibrillation. Read More

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January 2021

Atrial Myocyte NLRP3/CaMKII Nexus Forms a Substrate for Postoperative Atrial Fibrillation.

Circ Res 2020 09 30;127(8):1036-1055. Epub 2020 Jul 30.

Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany (J.H., A.P.M., T.V., C.E.M., M.T., I.H.A.-T., M.G., S.N., D.D.).

Rationale: Postoperative atrial fibrillation (POAF) is a common and troublesome complication of cardiac surgery. POAF is generally believed to occur when postoperative triggers act on a preexisting vulnerable substrate, but the underlying cellular and molecular mechanisms are largely unknown.

Objective: To identify cellular POAF mechanisms in right atrial samples from patients without a history of atrial fibrillation undergoing open-heart surgery. Read More

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September 2020

Heart failure-induced atrial remodelling promotes electrical and conduction alternans.

PLoS Comput Biol 2020 07 13;16(7):e1008048. Epub 2020 Jul 13.

School of Computer Science and Technology, Harbin Institute of Technology, Harbin, China.

Heart failure (HF) is associated with an increased propensity for atrial fibrillation (AF), causing higher mortality than AF or HF alone. It is hypothesized that HF-induced remodelling of atrial cellular and tissue properties promotes the genesis of atrial action potential (AP) alternans and conduction alternans that perpetuate AF. However, the mechanism underlying the increased susceptibility to atrial alternans in HF remains incompletely elucidated. Read More

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Demonstrating the mechanism of electrical alternans in cardiac tamponade: "the swinging heart".

Med J Aust 2020 07 29;213(2):66. Epub 2020 Jun 29.

Government Medical College and Hospital, Chandigarh, India.

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Incessant accelerated idioventricular rhythm mimicking preexcitation.

J Electrocardiol 2020 Jul - Aug;61:137-140. Epub 2020 Jun 11.

Arrhythmia Unit, Cardiology Department, Hospital La Luz - Quironsalud, Madrid, Spain.

ECG of patients with Wolf Parkinson White (WPW) syndrome may simulate other entities such as myocardial infarction, ventricular premature complexes, ventricular bigeminy, accelerated idioventricular rhythm, intermittent bundle branch block or electrical alternans. On the other hand, the opposite can also occur where these other conditions may simulate WPW. We present the case of a young patient referred for WPW ablation showing an incessant accelerated idioventricular rhythm mimicking preexcitation. Read More

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Simulation of the Effects of Extracellular Calcium Changes Leads to a Novel Computational Model of Human Ventricular Action Potential With a Revised Calcium Handling.

Front Physiol 2020 15;11:314. Epub 2020 Apr 15.

Computational Physiopathology Unit, Department of Electrical, Electronic and Information Engineering "Guglielmo Marconi", University of Bologna, Cesena, Italy.

The importance of electrolyte concentrations for cardiac function is well established. Electrolyte variations can lead to arrhythmias onset, due to their important role in the action potential (AP) genesis and in maintaining cell homeostasis. However, most of the human AP computer models available in literature were developed with constant electrolyte concentrations, and fail to simulate physiological changes induced by electrolyte variations. Read More

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Knockout of MD1 contributes to sympathetic hyperactivity and exacerbates ventricular arrhythmias following heart failure with preserved ejection fraction via NLRP3 inflammasome activation.

Exp Physiol 2020 06 6;105(6):966-978. Epub 2020 May 6.

Department of Cardiology, Renmin Hospital of Wuhan University, Wuchang, Wuhan, China.

New Findings: What is the central question of this study? In this study, we investigated whether MD1 interacted with the sympathetic nerves in ventricular arrhythmia (VA) during heart failure with preserved ejection fraction (HFpEF). What is the main finding and its importance? Mice with HFpEF showed increased susceptibility to VA, adverse electrical remodelling, impaired heart rate variability, enhanced sympathetic hyperactivity, activation of the NLRP3 inflammasome and increased interleukin-1β release. These changes induced by HFpEF were exacerbated by MD1 deficiency. Read More

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The Epileptic Heart: Concept and clinical evidence.

Epilepsy Behav 2020 04 25;105:106946. Epub 2020 Feb 25.

Harvard Medical School, Beth Israel Deaconess Medical Center, Division of Cardiovascular Medicine and Department of Neurology, Boston, MA United States of America.

Sudden unexpected death in epilepsy (SUDEP) is generally considered to result from a seizure, typically convulsive and usually but not always occurring during sleep, followed by a sequence of events in the postictal period starting with respiratory distress and progressing to eventual cardiac asystole and death. Yet, recent community-based studies indicate a 3-fold greater incidence of sudden cardiac death in patients with chronic epilepsy than in the general population, and that in 66% of cases, the cardiac arrest occurred during routine daily activity and without a temporal relationship with a typical seizure. To distinguish a primarily cardiac cause of death in patients with epilepsy from the above description of SUDEP, we propose the concept of the "Epileptic Heart" as "a heart and coronary vasculature damaged by chronic epilepsy as a result of repeated surges in catecholamines and hypoxemia leading to electrical and mechanical dysfunction. Read More

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[T-wave alternans and atrial tachycardia].

Orv Hetil 2020 Feb;161(7):275-277

Kardiológiai Osztály,Budai Irgalmasrendi KórházBudapest, Árpád fejedelem útja 7., 1027.

A 70-year-old male patient presented with acute respiratory failure. ECG at admission showed atrial tachycardia with macro T-wave alternans that disappeared as soon as normal sinus rhythm had returned. This ECG shape was not accompanied by either QT-prolongation or acute ischaemia. Read More

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February 2020

Pressure-impedance analysis: Assist the diagnosis and classification of ineffective esophageal motility disorder.

J Gastroenterol Hepatol 2020 Aug 29;35(8):1317-1324. Epub 2020 Jan 29.

Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan.

Background And Aim: We elucidated the clinical significance of distal contractile integral-to-esophageal impedance integral (EII) ratio (DCIIR) in ineffective esophageal motility (IEM) adult patients.

Methods: We recruited 101 patients with IEM (48.38 ± 1. Read More

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Delay differential equation-based models of cardiac tissue: Efficient implementation and effects on spiral-wave dynamics.

Chaos 2019 Dec;29(12):123128

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

Delay differential equations (DDEs) recently have been used in models of cardiac electrophysiology, particularly in studies focusing on electrical alternans, instabilities, and chaos. A number of processes within cardiac cells involve delays, and DDEs can potentially represent mechanisms that result in complex dynamics both at the cellular level and at the tissue level, including cardiac arrhythmias. However, DDE-based formulations introduce new computational challenges due to the need for storing and retrieving past values of variables at each spatial location. Read More

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December 2019

Examining Cardiomyocyte Dysfunction Using Acute Chemical Induction of an Ageing Phenotype.

Int J Mol Sci 2019 Dec 27;21(1). Epub 2019 Dec 27.

School of Life, Health and Chemical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK.

Much effort is focussed on understanding the structural and functional changes in the heart that underlie age-dependent deterioration of cardiac performance. Longitudinal studies, using aged animals, have pinpointed changes occurring to the contractile myocytes within the heart. However, whilst longitudinal studies are important, other experimental approaches are being advanced that can recapitulate the phenotypic changes seen during ageing. Read More

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December 2019

Clinical significance of 12 lead ECG changes in patients undergoing pericardiocentesis for cardiac tamponade.

Acta Cardiol 2021 Feb 27;76(1):76-79. Epub 2019 Dec 27.

Division of Cardiology, Thomas Jefferson University Hospital, Philadelphia, PA, USA.

Introduction: The electrocardiogram (ECG) is one of the initial tests done in patients suspected of having a cardiac Tamponade. Historically the emphasis has been on low QRS voltage and electrical alternans, which lacks specificity and sensitivity respectively. Majority of these studies included patients with pericardial effusions without tamponade. Read More

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February 2021

Lights, camera, path splitter: a new approach for truly simultaneous dual optical mapping of the heart with a single camera.

BMC Biomed Eng 2019 27;1. Epub 2019 Sep 27.

Sheikh Zayed Institute for Pediatric and Surgical Innovation: Children's National Health System, 6th floor, M7708, 111 Michigan Avenue NW, Washington, DC 20010, USA.

Background: Optical mapping of transmembrane voltage and intracellular calcium is a powerful tool for investigating cardiac physiology and pathophysiology. However, simultaneous dual mapping of two fluorescent probes remains technically challenging. We introduce a novel, easy-to-use approach that requires a path splitter, single camera and excitation light to simultaneously acquire voltage and calcium signals from whole heart preparations, which can be applied to other physiological models - including neurons and isolated cardiomyocytes. Read More

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September 2019

Microvolt T-wave alternans at the end of surgery is associated with postoperative mortality in cardiac surgery patients.

Sci Rep 2019 11 22;9(1):17351. Epub 2019 Nov 22.

Department of Anaesthesiology and Pain medicine, Seoul National University College of Medicine, Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul, 03080, Republic of Korea.

Microvolt T-wave alternans (MTWA), which reflects electrical dispersion of repolarization, is known to be associated with arrhythmia or sudden cardiac death in high risk patients. In this study we investigated the relationship between MTWA and postoperative mortality in 330 cardiac surgery patients. Electrocardiogram, official national data and electric chart were analysed to provide in-hospital and mid-term outcome. Read More

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November 2019