The Relationship between T-Wave Alternans and Adverse Cardiac Events in Patients with Congenital Long QT Syndrome:A Systematic Review and Meta-Analysis

Background:T-wave alternans(TWA)is a risk factor of ventricular arrhythmias or sudden cardiac death(SCD)in patients with ischemic cardiomyopathy.Nevertheless,the relationship between TWA and adverse cardiac events(ACE)in patients with congenital long QT syndrome(LQT)remains controversial.Methods:A systematic electronic search of PubMed,Embase and the Cochrane Library was conducted from database inception dates to 28 April 2021 and assessed the relationship between TWA and ACE in patients with LQTS.Sub-group analysis evaluated the association between microvolt TWA(MTWA)and ACE in different monitoring models and ECGlead numbers.Results:A pooled analysis of seven studies of 625 patients with LQTS showed that TWA was significantly associated with ACE(OR 3.16,95%CI 1.86–5.37,P<0.001).Advanced analysis showed that macroscopic TWA was significantly related to ACE(OR 6.01,95%CI 2.96–12.21,P<0.001),while MTWA did not(OR 0.92,95%CI 0.37–2.30,P=0.85).Sub-group analysis showed that MTWA recorded in 24 h continuous ECG(OR 6.79,95%CI 0.80–57.75,P=0.08)might have a stronger association with ACE than recorded in stress ECG(OR 0.28,95%CI 0.07–1.10,P=0.07).No difference was observed between MTWA measured in multi-lead ECG and limited ECG leads(P=0.15).Conclusions:Macroscopic TWA was significantly related to ACE in patients with LQTS.In terms of MTWA,MTWA recorded in 24 h continuous ECG might have a stronger association with ACE than stress ECG,but still deserves further evaluation.

Detection of T-wave Alternans in ECG Signals Using FRFT and Tensor Decomposition

T-wave alternans(TWA)refers to the periodic beat-to-beat variation in the amplitude of T-wave in the electrocardiogram(ECG)signal in an ABAB-pattern.TWA has been proven to be a very important indicator of malignant arrhythmia risk stratification.A new method to detect TWA by combining fractional Fourier transform(FRFT)and tensor decomposition is proposed.First,the T-wave vector is extracted from the ECG of each heartbeat,and its FRFT amplitudes at multiple orders are arranged to form a T-wave matrix.Then,a third-order tensor is composed of T-wave matrices of several consecutive heart beats.After tensor decomposition,projection matrices are obtained in three dimensions.The complexity of the projection matrix is measured by Shannon entropy to obtain feature vector to detect the presence of TWA.Results show that the sensitivity,specificity,and accuracy of the algorithm on the MIT-BIH database are 91.16%,94.25%,and 92.68%,respectively.This method effectively utilizes the fractional domain information of ECG,and shows the promising potential of the FRFT in ECG signal processing.

Adaptive Match-Filtering: A Biomedical Application to Identify T-Wave Alternans

T-wave alternans (TWA), consisting in an alternation of the electrocardiographic (ECG) repolarization segment (T-wave), is a promising index of the risk of sudden cardiac death. By definition, it is characterized by a frequency component, termed fTWA, that matches half heart rate. The heart-rate adaptive match filter (AMF) based method is a technique for automatic TWA identification from the digital ECG. Aim of the present study was to provide a complete technical description of the filter able to explain its methodological principles. The AMF is usually realized as a 6th order Butterworth filter with a narrow (0.12 Hz) passing band centered in fTWA. It is applied in a bidirectional fashion, so that final filtering order is 12. While extracting the TWA component, the AMF simultaneously filters out every ECG component including noise and artefacts, and thus results are very robust. Goodness of the technique was tested using 8 synthetic ECG tracings corrupted by typical noisy factors, such as white random noise, baseline wanderings, heart-rate variability, and others. Six ECG tracings were affected by 100 μV TWA, whereas two were not. Results indicate that the AMF-based method is able to prevent false-positive and false-negative detections and, thus, represents a useful tool for a reliable TWA identification.

On the basis of the morphology of the T-wave alternans: A Poincare mapping method research

Presently T-wave alternans (TWA) has become a clinical index of non-invasive diagnosis for heart sudden death prediction, and detecting T-wave alternate accurately is particularly important. This paper introduces an algorithm for detecting TWA using Poincare mapping method which is a technique for nonlinear dynamic systems to display periodic behavior. Sample series of beat to beat cycles were selected to prepare Poincare mapping method. Vector Angle Index (VAI), which is the mean of the difference between θi (the angle between the line connecting the i point to the origin and the X axis) and 45 degrees was used to present the presence or absence of TWA. The value of 0.9 rad ≤ VAI ≤ 1.03 rad is accepted as a level determinative for presence of TWA. VAI via Poincare mapping method (PM) is used for correlation analysis with T-wave alternans voltage (Vtwa) by way of the spectral method (SM). The cross-correlation coefficient between Vtwa and VAI is γ = 0.8601. The algorithm can identify the absence and presence of TWA accurately and provide idea for further study of TWA-PM.

Application of T-Wave Alternans in Evaluation of Prognosis in Patients with Intracerebral Hemorrhage

Objective: To explore the application value of electrocardiograph (ECG) T-wave Alternans (TWA) anomaly in acute stage of intracerebral hemorrhage patients. Methods: We choose 1175 intracerebral hemorrhage patients whose conventional 12-lead ECG has TWA in our hospital from January 2011 to December 2015, 751 patients without TWA in the same period as the control group, compared the volume of intracerebral hemorrhage, bleeding site and mortality between the 2 groups. Results: In TWA group, 247 cases died, 361 cases with massive intracerebral hemorrhage, 298 cases with brain stem hemorrhage;in TWA negative group (control group), 41 cases died, 93 cases with massive brain hemorrhage, 64 cases with brain stem hemorrhage. There are statistical differences between two groups (P Conclusion: The occurrence of TWA is significantly related to the volume of bleeding, the bleeding site and mortality, and can be used as an important parameter in the prognosis of intracerebral hemorrhage.

Microvolt T-wave alternans complemented with electrophysiologic study for prediction of ventricular tachyarrhythmias in patients with arrhythmogenic right ventricular cardiomyopathy: a long-term follow-up study

Background: The long-term predicted value of microvolt T-wave alternans (MTWA) for ventricular tachyarrhythmia in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) remains unclear. Our study explored the characteristics of MTWA and its prognostic value when combined with an electrophysiologic study (EPS) in patients with ARVC. Methods: All patients underwent non-invasive MTWA examination with modified moving average (MMA) analysis and an EPS. A positive event was defined as the first occurrence of sudden cardiac death, documented sustained ventricular tachycardia (VT), ventricular fibrillation, or the administration of appropriate implantable cardioverter defibrillator therapy including shock or antitachycardia pacing. Results: Thirty-five patients with ARVC (age 38.6 ± 11.0 years;28 males) with preserved left ventricular (LV) function were recruited. The maximal TWA value (MaxValt) was 17.0 (11.0–27.0)μV. Sustained VT was induced in 22 patients by the EPS. During a median follow-up of 99.9 ± 7.7 months, 15 patients had positive clinical events. When inducible VT was combined with the MaxValt, the area under the curve improved from 0.739 to 0.797. The receiver operating characteristic curve showed that a MaxValt of 23.5 μV was the optimal cutoff value to identify positive events. The multivariate Cox regression model for survival showed that MTWA (MaxValt, hazard ratio [HR], 1.06;95% confidence interval [CI], 1.01–1.11;P = 0.01) and inducible VT (HR, 5.98;95% CI, 1.33–26.8;P = 0.01) independently predicted positive events in patients with ARVC. Conclusions: MTWA assessment with MMA analysis complemented by an EPS might provide improved prognostic ability in patients with ARVC with preserved LV function during long-term follow-up.

Isolated Hyperacute T-Waves in West Nile Encephalitis Indicating Atypical Variant of Stress-Induced Cardiomyopathy

Several cardiac outcomes have been reported with West Nile-encephalitis;however, the underlying pathophysiology remains complex. We present a 42-year-old female, with multiple sclerosis, whose neurological symptoms and respiratory decline were finally explained by the diagnosis of West Nile-encephalitis. During her admission, the isolated peaked T-waves indicated the underlying stress-induced cardiomyopathy. The absence of all other causes of hyperacute T-waves, their subsequent resolution with the resolution of infection and improvement in wall motion abnormalities, further supported the association. This case highlights the importance of considering hyperacute T-waves in an approach towards the diagnosis of WNV-encephalitis related atypical variant of stress-induced cardiomyopathy.

Biventricular pulsus alternans: An echocardiographic finding in patient with pulmonary embolism

Pulsus alternans is characterized by regular rhythm with beat-to-beat alternation of systolic pressures. Left ventricular alternans is usually found in severe left ventricular dysfunction due to cardiomyopathy, coronary artery disease, systemic hypertension, and aortic stenosis. Right ventricular alternans is usually associated with left ventricular alternans, right ventricular dysfunction, pulmonary embolism, and pulmonary hypertension. Biventricular alternans is rare and associated with severe left ventricular dysfunction and left anterior descending coronary artery disease. The exact mechanism of pulsus alternans has not been clearly delineated, and it has been remained a subject of investigation and conjecture since the nineteenth century. Two fundamental mechanisms have been proposed to explain ventricular alteration. The first, based on the Frank-Starling mechanism, proposes beat-to-beat alteration in end-diastolic volume accounted for the alternating contractile force. The second proposed mechanism which explains the physiology of pulsus alternans involves the abnormal calcium handling by cardiac myocytes. To the best of our knowledge, biventricular alternans in pulmonaryembolism has not been previously reported in the medical literature. We present and discuss the mechanisms of pulsus alternans and its clinical implications.

Analysis of the Q-T Dispersion and T Wave Alternans in Patients with Epilepsy

Objectives: There is a high rate of sudden death in epilepsy patients, part of which is sudden cardiac death. By investigating ECG T wave alternans and Q-T dispersion changes of epilepsy patients, we may predict the possibility of the occurrence of sudden death and provide basis for clinical prevention. Methods: Selecting 587 cases of epilepsy patients as the study group, 672 same period cases of healthy persons as the control group;Analyzing the effect of epilepsy on ECG T wave alternans and Q-T dispersion with the standard 12 lead ECG. Results: The study group had a significantly prolonged Q-T dispersion and an increased incidence of T wave alternans than that of the control group;Compared with other seizure types, tonic clonic seizure and absence seizure had a significantly prolonged Q-T dispersion and an increased occurrence rate of T wave alternans. Conclusions: Epilepsy patients ECG T wave alternans and Q-T dispersion has higher abnormal rate, and are prone to sudden cardiac death;Routine ECG(RECG) T wave alternans and Q-T dispersion changes can provide guidance for clinical prevention of sudden unexpected death in epilepsy (SUDEP).

急性脑出血合并急性心肌梗死心电图QRS波电交替1例报告

1病例资料患者女,74岁,于我院神经内科就诊期间突发意识不清、瞳孔对光反射消失、呼吸停止、脉搏不可触及,立即转入抢救室行气管插管呼吸机辅助呼吸及静脉输液等抢救措施。2021年5月14日08:15进入抢救室后测量血压为235/184 mmHg(1 mmHg=0.133 kPa),完善头颅+胸部CT、心电图、血常规、心肌损伤和心力衰竭标志物、新型冠状病毒抗体与核酸检查。

Cardiac and non-cardiac causes of T-wave inversion in the precordial leads in adult subjects: A Dutch case series and review of the literature

AIM: To describe the electrocardiographic(ECG) phenomena characterized by T-wave inversion in the precordial leads in adults and to highlight its differential diagnosis. METHODS: A retrospective chart review of 8 adult patients who were admitted with ECG T-wave inversion in the anterior chest leads with or without prolongation of corrected QT(QTc) interval. They had different clinical conditions. Each patient underwent appropriate clinical assessment including investigation for myocardial involvement. Single and multimodality noninvasive, semi-invasive and invasive diagnostic approach were used to ascertain the diagnosis. The diagnostic assessment included biochemical investigation, cardiac and abdominal ultrasound, cerebral and chest computed tomography, nuclear medicine and coronary angiography.RESULTS: Eight adult subjects(5 females) with a mean age of 66 years(range 51 to 82) are analyzed. The etiology of T-wave inversion in the precordial leads were diverse. On admission, all patients had normal blood pressure and the ECG showed sinus rhythm. Five patients showed marked prolongation of the QTc interval. The longest QTc interval(639 ms) was found in the patient with pheochromocytoma. Giant T-wave inversion(≥ 10 mm) was found in pheochromocytoma followed by electroconvulsive therapy and finally ischemic heart disease. The deepest T-wave was measured in lead V3(5 ×). In 3 patients presented with mild T-wave inversion(patients 1, 5 and 4 mm), the QTc interval was not prolonged(432, 409 and 424 msec), respectively.CONCLUSION: T-wave inversion associated with or without QTc prolongation requires meticulous history taking, physical examination and tailored diagnostic modalities to reach rapid and correct diagnosis to establish appropriate therapeutic intervention.

誓约的记忆秋之回忆6T-wave

从第一部《秋之回忆》发售至今，已然十年。在这十年中，KID以及它的继承者5pb为我们带来了包括正传、外传和后续故事在内的十三部作品。初代、雪莹、想君和从今以后的巅峰，中断胶片的争议，安可的质疑，无疑不深深刺激着玩家的心里。

心电T波电交替检测算法综述

现代临床研究表明,T波电交替(TWA)是一项预测心源性猝死的重要指标。自TWA现象被发现以来,相继出现了很多TWA检测的算法,大体上可以分为频域法和时域法两大类。文中对这两大类典型算法进行系统的分类阐述,讨论它们的优缺点;对其他算法做简要论述;最后探讨了影响TWA检测的因素以及TWA检测算法的发展方向。

T波电交替的分析研究

通过自行研制的检测系统采集心电信号 ,采用快速傅立叶转换进行数据处理 ,将心电图上T波段幅度的变化转变成能量谱。同时引入 T波电交替系数 TWAI用于电交替的测定 ,其分析结果定量性较好 ,显著优于以前在心电图上肉眼观察的效果。临床研究表明 ,TWAI是预测发生恶性室性心律失常与心脏性猝死的独立的、具有统计学意义的指标。

空心莲子草的化学成分研究

目的研究苋科空心莲子草[Alternan theraphilox eroid es(Mart.)Griseb]的化学成分。方法有机溶剂提取,运用硅胶柱色谱、Sephadex LH-20凝胶柱色谱等色谱技术分离纯化,利用化学方法和多种波谱技术(1H-NMR,13C-NMR,MS等)进行结构鉴定。结果从乙醇提取物的氯仿和醋酸乙酯萃取部分分得7个化合物:竹节参苷Ⅳa(chikusetsusaponin-Ⅳa,Ⅰ)、齐墩果酸-3-O-β-D-葡萄糖醛酸苷(calendulosideE,Ⅱ)、大黄酚-8-O-β-D-吡喃葡萄糖苷(chrysophenol-8-O-β-D-glucopyranoside,Ⅲ)、土大黄苷(rhaponticin,Ⅳ)、α-菠甾醇(α-Spinasterol,Ⅴ)、β-谷甾醇(β-Sitosterol,Ⅵ)、正三十二烷酸(Lacceroicacid,Ⅶ)。结论化合物Ⅰ、Ⅲ、Ⅳ为首次从该植物中得到,为该药的开发利用提供了信息。

心电T波交替的改进谱估计检测方法

目的针对经典谱估计法的缺点 ,利用现代谱估计法检测心电中的TWA(Twavealternans)信号 ,为TWA信号的检测分析提供新的手段。方法临床采集 1 5位心脏病患者和 8位健康人的心电向量信号 ,使用本文提出的改进的谱估计法对其进行心电TWA的检测。结果检测结果说明 ,使用现代谱估计法的改进谱估计法能够准确的检测到心电信号中隐含的TWA信号 ,且谱线光滑 ,分辨率高。结论改进的谱估计法提供了一种新的TWA检测手段 ,可以更全面的检测和观察心电中可能隐含的TWA信号。

基于T波最大值的T波电交替分析法

提出了一种基于T波最大值T波电交替(T-wave alternans,TWA)的快速傅氏变换(Fast fouriertransform,FFT)分析法。该方法能在减少抽样频率的条件下,保证计算精度。基于T波最大值的方法还解决了固定T波的取样点随着心率的变化而变化问题。该方法对连续128个正常心跳周期的ST-T结构中的T波最大值进行FFT变换,进而可以得到其功率谱曲线图。该功率谱图可反映TWA。

基于心电图ST-T段的心肌缺血检测方法研究进展

心电图是一种经济、方便、无创的心肌缺血检测工具。心肌缺血主要的临床表现为心电图ST-T段发生变化(即ST段和T波)。本文对基于心电图ST-T段的心肌缺血检测方法进行了综述,其中ST段检测主要包括形态、大小(幅值和间期)两方面,而T波检测包括形态、T波峰末间期、T波电交替等方面,最后对心肌缺血检测的关键技术进行了总结和展望。

空心莲子草在稻田生态系统中的生长特性及对水稻生长发育的影响

为了解空心莲子草在正常耕作稻田中的入侵能力与水稻对该草的抵抗能力,本文通过在秧苗移栽后的稻田中移植少量空心莲子草繁殖体,人工模拟空心莲子草入侵稻田的方法,研究了该草在稻田中的入侵生长繁殖特性及其对水稻生长发育的影响。结果显示:在人工移入空心莲子草后的第一个水稻生长季内,空心莲子草长势较弱,其植株克隆数与直立茎秆数从水稻分蘖前期至成熟期均无显著变化,仅株高增长极显著,但茎秆纤细柔软,部分茎秆顶端弱化,叶片弱小卷曲,出芽量很低或几乎没有新芽生长。空心莲子草对水稻分蘖、有效分蘖与株高等参数均无显著影响。空心莲子草在田埂上与稻田边缘的生长主要表现为该草的覆盖度、直立茎秆数与株高的显著增加,难以向稻田中扩散生长。研究结果表明,空心莲子草在耕作稻田中不能形成严重入侵态势。建议保持稻田于耕作状态,可有效防止空心莲子草的入侵。