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.

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.

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.

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。

Entire process of electrocardiogram recording of Wellens syndrome:A case report

BACKGROUND Wellens syndrome is an electrocardiogram(ECG)pattern seen in high-risk patients with unstable angina pectoris.It is characterized by inverted or biphasic T-waves that change into positive or pseudo-normalized waves at precordial leads when the patient experiences an angina attack;however,the mechanism for this condition remains unclear.CASE SUMMARY A 47-year-old male patient experienced repeated,unprovoked episodes of chest pain for>20 d,with worsening during the previous day.On the day of admission,he experienced episodes of paroxysmal chest pain lasting more than 30 min,in addition to radiating pain to the left arm and exertional dyspnea.The patient presented to the emergency department with no chest pain or other discomfort at that time.ECG at presentation showed sinus tachycardia and Twave changes,which were identified as Wellens syndrome when combined with previous ECG findings.ECGs and myocardial enzymology examinations were normal when angina was present,but the ECG showed inverted or biphasic Twaves when angina was absent.After percutaneous coronary intervention,the ECGs demonstrated inverted or biphasic T-waves in the anterior precordial leads on days 0,1,and 2,but normal T-waves on day 3.The ECGs showed no subsequent ischemic ST-T-wave changes.CONCLUSION The Wellens syndrome pseudo-normalized T-waves likely reflect development of unstable angina pectoris into the hyperacute phase of ST-segment elevation myocardial infarction.

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.

T-wave oversensing and inappropriate shocks in implantable cardioverter defibrillators

The implantable cardioverter defibrillator （ICD） represents today the treatment and prophylaxis of choice for patients at risk for sustained ventricular tachyarrhythmias.1-6 Accurate sensing of ventricular tachyarrhythmias is a critical aspect of the function of ICD. All currently available models include algorithms with variable sensitivity, allowing adjustments which optimize the detection of low amplitude signals during ventricular tachyarrhythmia. However,