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.

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.

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).

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.

Neutrophil-lymphocyte ratio:A prognostic tool in patients with inhospital cardiac arrest

BACKGROUND In-hospital cardiac arrest(IHCA) portends a poor prognosis and survival to discharge rate. Prognostic markers such as interleukin-6, S-100 protein and high sensitivity C reactive protein have been studied as predictors of adverse outcomes after return of spontaneous circulation(ROSC); however; these variables are not routine laboratory tests and incur additional cost making them difficult to incorporate and less attractive in assessing patient's prognosis. The neutrophil-lymphocyte ratio(NLR) is a marker of adverse prognosis for many cardiovascular conditions and certain types of cancers and sepsis. We hypothesize that an elevated NLR is associated with poor outcomes including mortality at discharge in patients with IHCA.AIM To determine the prognostic significance of NLR in patients suffering IHCA who achieve ROSC.METHODS A retrospective study was performed on all patients who had IHCA with the advanced cardiac life support protocol administered in a large urban community United States hospital over a one-year period. Patients were divided into two groups based on their NLR value(NLR < 4.5 or NLR ≥ 4.5). This cutpoint was derived from receiving operator characteristic curve analysis(area under the curve = 0.66) and provided 73% positive predictive value, 82% sensitivity and42% specificity for predicting in-hospital death after IHCA. The primary outcome was death or discharge at 30 d, whichever came first.RESULTS We reviewed 153 patients with a mean age of 66.1 ± 16.3 years; 48% were female.In-hospital mortality occurred in 65%. The median NLR in survivors was 4.9(range 0.6-46.5) compared with 8.9(0.28-96) in non-survivors(P = 0.001). A multivariable logistic regression model demonstrated that an NLR above 4.55[odds ratio(OR) = 5.20, confidence interval(CI): 1.5-18.3, P = 0.01], older age(OR= 1.03, CI: 1.00-1.07, P = 0.05), and elevated serum lactate level(OR = 1.20, CI:1.03-1.40, P = 0.02) were independent predictors of death.CONCLUSION An NLR ≥ 4.5 may be a useful marker of increased risk of death in patients with IHCA.

The first snapshot study on horizontal distribution and identification of five peritrich ciliates (Genus Vorticella Linnaeus and Zoothamnium Bory de St. Vincent) from the eastern Indian Ocean

Epipont peritrich ciliates are one of the most sessilie protists that attached to the substrate of zooplankton communities especially copepods and crustaceans. Peritrich ciliates can be solitary or colonial form found from the coastal zones and embayment around the world. Present research report is the first snapshot study of the peritrich ciliates and the horizontal distribution in open waters from surface to 200 m depth in the eastern Indian Ocean. Recently, five peritrich ciliates, e.g., Vorticella oceanica, Zootharnnium alternans, Z. alrasheidi, Z. pelagicum, and Z. marinum were collected from plankton net tow samples during the cruise from April 10 to May 13, 2014. The characteristics of the peritrich ciliate were determined according to the shape of the zooids, the ciliary structure and the stalks. The morphometric shape, sizes and characters also explained by examination under light/scanning electron microscopy. Vorticella oceanica and Z. pelagicum showed their association with host such as diatom （i.e, Chaetoceros coarctatus） and copepod （Oithona brevicornis） including some individuals around the dinoflagellate species （Ceraitum tripose）. The distribution of these sessilid ciliates was dominated by the V. oceanica, Z. pelagicum and Z. rnarinurn at the southeast zone while the large colonies of Z. alrasheidi observed at the Bay of Bengal. This distribution can be influenced by substrate availability like diatom （Ch. coarctatus） and copepods （O. brevicornis）.

Complex atrial tachycardia with alternating cycle length:What is the mechanism?

Background Atrial tachycardia(AT)with cycle length(CL)alternans is uncommon and conventional mapping of this AT remains challenging. We used an ultrahigh density mapping system to rapidly map complicated circuits with sufficient spatial resolution and electrogram quality to elucidate the precise mechanism of this special ATs. Methods Of 210 consecutive patients with clinical ATs who underwent catheter ablation with the ultrahigh density mapping system,4 patients(1.9%)with CL alternans were identified. The AT alternating cycles mapped by the Rhythmia mapping system for long CL were 317±51(range 245-355)ms and for short CL were 282±51(range 235-333)ms. Both long and short cycles followed in 1∶1 sequence in all 4 patients(longshort-long-short). Results By comparing the separate maps with long and short CL,we classified ATs with CL alternans into 2 types. In type 1,CL alternans resulted from an intermittent 2∶1 conduction block through the slow conduction channel in the small circuit. In type 2,CL alternans caused by the alternated conduction velocity passing through the conduction gap were manifested. Ablation at the fractionated potentials contributes to the termination of AT in 3 of the 4 patients. Conclusions Ultrahigh density mapping system can accurately identify the mechanism of complex ATs with alternating CL. The CL alternans may be related to the intermittent conduction block within the channel of the small circuitor different conduction velocity through the identical channel. Fractionated electrogram recorded in the common isthmus or some"conduction gaps"may be a reasonable approach to terminate these ATs.