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"T wave alternans" OR "MTWA"

Gary Tse, Bryan P Yan
Sudden cardiac death, frequently due to ventricular arrhythmias, is a significant problem globally. Most affected individuals do not arrive at hospital in time for medical treatment. Therefore, there is an urgent need to identify the most-at-risk patients for insertion of prophylactic implantable cardioverter defibrillators. Clinical risk markers derived from electrocardiography are important for this purpose. They can be based on repolarization, including corrected QT (QTc) interval, QT dispersion (QTD), interval from the peak to the end of the T-wave (Tpeak - Tend), (Tpeak - Tend)/QT, T-wave alternans (TWA), and microvolt TWA...
October 4, 2016: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
Riqing Chen, Yingsong Huang, Jian Wu
BACKGROUND AND OBJECTIVE: P-wave detection is one of the most challenging aspects in electrocardiograms (ECGs) due to its low amplitude, low frequency, and variable waveforms. This work introduces a novel multi-window detection method for P-wave delineation based on the bilateral accumulative area. METHOD: The bilateral accumulative area is calculated by summing the areas covered by the P-wave curve with left and right sliding windows. The onset and offset of a positive P-wave correspond to the local maxima of the area detector...
September 15, 2016: Computers in Biology and Medicine
Samy A Abdelghani, Todd M Rosenthal, Daniel P Morin
BACKGROUND: Heart disease is a major cause of death in industrialized nations, with approximately 50% of these deaths attributable to sudden cardiac arrest. If patients at high risk for sudden cardiac arrest can be identified, their odds of surviving fatal arrhythmias can be significantly improved through prophylactic implantable cardioverter defibrillator placement. This review summarizes the current knowledge pertaining to surface electrocardiogram (ECG) predictors of sudden cardiac arrest...
2016: Ochsner Journal
Richard Gordan, Nadezhda Fefelova, Judith K Gwathmey, Lai-Hua Xie
In the present study, we have used a genetic mouse model that lacks cyclophilin D (CypD KO) to assess the cardioprotective effect of mitochondrial permeability transition pore (mPTP) inhibition on Ca(2+) waves and Ca(2+) alternans at the single cell level, and cardiac arrhythmias in whole-heart preparations. The protonophore carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone (FCCP) caused mitochondrial membrane potential depolarization to the same extent in cardiomyocytes from both WT and CypD KO mice, however, cardiomyocytes from CypD KO mice exhibited significantly less mPTP opening than cardiomyocytes from WT mice (p<0...
September 2, 2016: Cell Calcium
Tharmathai Ramanan, Kathir Balakumaran, Sairekha Ravichandran, Stephen J Ganocy, Ganiyu Oshodi, Otto Costantini, Mary Dettmer, Peter J Leo, Elizabeth S Kaufman
INTRODUCTION: Microvolt T-wave alternans (MTWA) analysis can identify patients at low risk of sudden cardiac death who might not benefit from an implantable cardioverter-defibrillator (ICD). Current spectral methodology for performing MTWA analysis may "miss" part of the T-wave in patients with QT prolongation. The value of T-wave window adjustment in patients with structural heart disease has not been studied. METHODS: We assembled MTWA data from 5 prior prospective studies including 170 patients with reduced left ventricular ejection fraction, adjusted the T-wave window to include the entire T-wave, and reanalyzed MTWA...
August 4, 2016: Journal of Electrocardiology
Jonathan W Waks, Larisa G Tereshchenko, Rulan S Parekh
Patients with end stage renal disease (ESRD) on hemodialysis experience a high incidence of cardiovascular mortality, and sudden cardiac death (SCD) accounts for approximately 25% of all deaths in this patient population. Despite this high risk of SCD, many non-invasive SCD risk stratification tools that are frequently applied to other patient populations (such as those with prior myocardial infarction and reduced left ventricular systolic function) may be less useful markers of increased SCD risk in ESRD. Improved SCD risk stratification tools for use specifically in patients on hemodialysis are therefore necessary to optimally target use of primary prevention interventions aimed at decreasing SCD incidence...
July 28, 2016: Journal of Electrocardiology
Salvatore Gruttadauria, Duilio Pagano, Alessandro Tropea, Davide Cintorino, Luisa Castellana, Pasquale Bonsignore, Calogero Ricotta, Gaetano Piccolo, Giovanni Vizzini, Angelo Luca
BACKGROUND: The surgical therapy of choice for hepatocellular carcinoma (HCC) is liver transplantation (LT) or hepatic resection, although only a small percentage of patients can undergo these procedures. Microwave thermal ablation (MWTA) can be an effective alternative treatment for HCC that complicates a cirrhotic liver disease, either as a final procedure or for downstaging patients on the waiting list for LT, or in combination with resective surgery to achieve oncological radicality...
October 2016: Journal of Laparoendoscopic & Advanced Surgical Techniques. Part A
Muhammad A Hasan, Vijay S Chauhan, Sridhar Krishnan
BACKGROUND: T-wave alternans (TWA) is defined as a consistent variation in the repolarization morphology that repeats on every other beat. This study aimed to evaluate beat-to-beat TWA detection using the Ensemble EMD (EEMD) method. METHOD: A total of 108 recordings of standard 12-lead ECGs of 69 healthy subjects (17 females, 42±18 years; 52 males, 40±13 years) and 39 cardiac-condition patients (ischemic cardiomyopathy; ICM and dilated cardiomyopathy; DCM) with left ventricular ejection fractions (LVEF) ≤40% were studied...
October 1, 2016: Computers in Biology and Medicine
Marco Paulo Tomaz Barbosa, Manoel Otávio da Costa Rocha, Elson Santos Neto, Fernando Vieira Brandão, Federico Lombardi, Antonio Luiz Pinho Ribeiro
BACKGROUND: Chagas disease (ChD) may lead to life-threatening heart disease, including malignant ventricular arrhythmias. The use of implantable cardioverter defibrillators (ICDs) has become the main therapeutic strategy for secondary prevention of SCD in Chagas disease (ChD). Microvolt T-wave alternans (MTWA) is a direct measure of ventricular repolarization instability and has emerged as a potentially useful way of determining arrhythmia vulnerability. However, this methodology has not been evaluated in patients with ChD...
November 1, 2016: International Journal of Cardiology
Richard L Verrier, Bruce D Nearing, Bryan Olin, Paul Boon, Steven C Schachter
OBJECTIVE: Reports of cardiac arrhythmias and cardiac pathology at postmortem examination of patients with epilepsy suggest a possible cardiac component of risk for sudden unexpected death in epilepsy (SUDEP). T-wave alternans (TWA) is an established marker of cardiac electrical instability and risk for sudden death in patients with cardiovascular disease. We determined the TWA level before vagus nerve stimulation (VNS) system implantation and subsequently the effect of VNS on TWA in patients with drug-resistant epilepsy...
September 2016: Epilepsy & Behavior: E&B
Aapo L Aro, Tuomas V Kenttä, Heikki V Huikuri
Microvolt T-wave alternans (TWA), characterised as beat-to-beat fluctuation of T-wave amplitude and morphology, is an electrophysiological phenomenon associated clinically with impending ventricular arrhythmias and is an important marker of arrhythmia risk. Currently, two main methods for the detection of TWA exist, namely, the spectral method and the time-domain modified moving average method; both are discussed in this review. Microvolt TWA has been associated with cardiovascular mortality and sudden cardiac death in several clinical studies involving >14,000 subjects with reduced as well as preserved left ventricular function...
May 2016: Arrhythmia & Electrophysiology Review
Tilak Pasala, Mary Dettmer, Peter J Leo, Kenneth R Laurita, Elizabeth S Kaufman
INTRODUCTION: In experimental models, spatial dispersion of repolarization (DOR) due to discordant cellular alternans predisposes to ventricular fibrillation. To test the hypothesis that microvolt T-wave alternans (MTWA) in humans causes spatial DOR, we measured Tpeak-Tend interval (Tpe) and Tpe/QT ratio, electrocardiographic indices of spatial DOR. METHODS: Mean Tpe and Tpe/QT were compared in ischemic cardiomyopathy patients with positive and negative MTWA studies...
September 2016: Journal of Electrocardiology
Aditya V S Ponnaluri, Luigi E Perotti, Michael Liu, Zhilin Qu, James N Weiss, Daniel B Ennis, William S Klug, Alan Garfinkel
Heart failure is a leading cause of death, yet its underlying electrophysiological (EP) mechanisms are not well understood. In this study, we use a multiscale approach to analyze a model of heart failure and connect its results to features of the electrocardiogram (ECG). The heart failure model is derived by modifying a previously validated electrophysiology model for a healthy rabbit heart. Specifically, in accordance with the heart failure literature, we modified the cell EP by changing both membrane currents and calcium handling...
June 2016: PLoS Computational Biology
Fernanda Justo, Henrique Fuller, Bruce D Nearing, Sridharan Rajamani, Luiz Belardinelli, Richard L Verrier
BACKGROUND: Myocardial ischemia carries dual risk for initiating atrial and ventricular arrhythmias that can be exacerbated by adrenergic stimulation. OBJECTIVE: The purpose of this study was to investigate whether selective inhibition of the cardiac late sodium current (INa) with eleclazine decreases susceptibility to ischemia-induced atrial fibrillation (AF) and atrial and ventricular repolarization abnormalities before and after epinephrine infusion. METHODS: In chloralose-anesthetized, open-chest, male Yorkshire pigs (n = 12), atrial and ventricular ischemia was induced by partial occlusion of the left circumflex coronary artery proximal segment to reduce flow by 75%...
September 2016: Heart Rhythm: the Official Journal of the Heart Rhythm Society
Mehmet Yaman, Uğur Arslan, Hasan Ali Gümrükçüoğlu, Musa Şahin, Hakkı Şimşek, Serkan Akdağ
BACKGROUND AND OBJECTIVES: Studies reveal that the microvolt T wave alternans (MTWA) test has a high negative predictive value for arrhythmic mortality among patients with ischemic or non-ischemic cardiomyopathy. In this study, we investigate the effects of trimetazidine treatment on MTWA and several echocardiographic parameters in patients with stable coronary artery disease. SUBJECTS AND METHODS: One hundred patients (23 females, mean age 55.6±9.2 years) with stable ischemic heart disease were included in the study group...
May 2016: Korean Circulation Journal
Yuanyuan Tang, Zhen Chen, Xiaofeng Hou, Quanpeng Wang, Feng Zhang, Jiangang Zou
OBJECTIVE: To study the effects of cardiac resynchronization therapy (CRT) with different pacing rates and modes on MTWA.
 METHODS: From March, 2012 to October, 2014, 43 patients who received CRT or CRT-D implantation in the first affiliated hospital, Nanjing Medical University were studied. Time-domain MTWA test were assessed following CRT implantation. MTWA was measured at 90 min(-1) and 110 min(-1) by treadmill exercise test with GE CASE 8000 during CRT-on (BIV biventricular) and CRT-off (RA right atrial) pacing modes...
April 2016: Zhong Nan da Xue Xue Bao. Yi Xue Ban, Journal of Central South University. Medical Sciences
Bruce D Nearing, Imad Libbus, Badri Amurthur, Bruce H Kenknight, Richard L Verrier
BACKGROUND: Chronic vagus nerve stimulation (VNS) applied to produce biomimetic levels of parasympathetic activation is feasible, well tolerated, safe, improves left ventricular ejection fraction, NYHA class, heart rate variability, and baroreflex function, and reduces T-wave alternans (TWA) in patients with chronic heart failure. However, the acute effects of VNS on beat-to-beat heart rate dynamics have not been systematically characterized in humans. METHODS AND RESULTS: We evaluated acute effects of VNS on R-R-interval dynamics during the VNS titration period in patients (n = 59) enrolled in ANTHEM-HF trial by quantifying effects during continuous cyclic VNS (14-seconds on-time, 66-seconds off-time) adjusted to the maximum tolerable dose without excessive (<4 bpm) bradycardia during the 10-week titration period...
September 2016: Journal of Cardiovascular Electrophysiology
Joachim Seegers, Leonard Bergau, Pascal Muñoz Expósito, Axel Bauer, Thomas H Fischer, Lars Lüthje, Gerd Hasenfuß, Tim Friede, Markus Zabel
In patients treated with implantable cardioverter defibrillator (ICD), prediction of both overall survival and occurrence of shocks is important if improved patient selection is desired. We prospectively studied the predictive value of biomarkers and indexes of cardiac and renal function and spectral microvolt T-wave alternans testing and 24-hour Holter variables in a population who underwent first ICD implantation. Consecutive patients in sinus rhythm with ischemic or dilated cardiomyopathy scheduled for primary or secondary prophylactic ICD implantation were enrolled...
July 1, 2016: American Journal of Cardiology
Ichiro Watanabe, Leonard S Gettes
The factors responsible for the ST-T wave alternans (STTA) and associated arrhythmias during acute ischemia have not been clarified.In acutely ischemic porcine myocardium, we recorded transmural unipolar and bipolar electrocardiograms and mid-myocardial extracellular K(+) ([K(+)]e) from the center of the ischemic zone during 8-minute episodes of ischemia. Two different STTAs occurred. The initial STTA, which occurred at 4 minutes 15 seconds ± 12 seconds of ischemia during sinus rhythm, was most prominent in the subendocardium, independent of [K(+)]e and activation block, and heart rate dependent...
May 25, 2016: International Heart Journal
Ozgur Surgit, Mehmet Erturk, Ozgur Akgul, Mehmet Gul, Hamdi Pusuroglu, Ibrahim Faruk Akturk, Fatih Uzun, Umut Somuncu, Ahmet Ayaz, Abdurrahman Eksik
BACKGROUND: Slow coronary artery flow (SCF) is characterized by angiographically confirmed delayed vessel opacification in the absence of any evidence of obstructive epicardial coronary artery disease. Microvolt T-wave alternans (MTWA) is defined as beat-to-beat changes in shape, amplitude, or timing of ST segments and T waves, and is utilized in predicting sudden cardiac death and life-threatening malign ventricular arrhythmias in high-risk patients. In our study, we aimed to evaluate the effects of slow coronary artery flow on MTWA...
May 2014: Acta Cardiol Sin
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