Analysis Of Ventricular Late Potentials Research Articles

Parameters Of Myocardial Electrical Instability In Patients After Myocardial Infarction Comorbid With A Novel Coronavirus Infection (COVID-19)

Objective — This article aims to assess parameters of myocardial electrical instability and arrhythmic events in patients after myocardial infarction (MI), with and without ST-segment elevation, comorbid/noncomorbid with a novel coronavirus infection (COVID-19) using a long-term electrocardiographic (ECG) monitoring. Methods — The study included 64 subjects: 25 (39%) patients with MI comorbid with COVID-19 (MI+C group) and 39 (61%) patients with MI noncomorbid with a novel coronavirus infection (MI group). The mean age of patients was 54.3±6.8 years. A long-term ECG monitoring for 97.4 (95% CI 77.9-115.2) hours was performed with Astrocard®-Telemetry system (Meditek JSC, Russia), starting from the 4th day of MI. Rhythm and conduction disorders, along with ischemic episodes were recorded; an analysis of ventricular late potentials, heart rate turbulence, and QT dispersion was carried out. Results — There were no differences in the frequency of delayed afterdepolarizations in MI and MI+C groups: 15-28% and 18-33% of patients, respectively. An analysis of turbulence parameters did not reveal statistically significant differences between the groups. Such arrhythmic events as frequent supraventricular extrasystole and life-threatening arrhythmias (ventricular extrasystole of grade 4A and higher sensu B. Lown and M. Wolf) were recorded significantly more often in the MI+C group than in the MI group: 48% vs. 20.5% (p=0.021) and 24% vs. 5.1% (p=0.026), respectively. Conclusion — The novel coronavirus infection (COVID-19) exacerbates myocardial electrophysiological heterogeneity in the acute cardiovascular event and is associated with an increase in clinically significant arrhythmic events.

HEART RATE VARIABILITY, VENTRICULAR LATE POTENTIALS AND HEART RATE TURBULENCE AS INDICATORS OF CORONARY REPERFUSION IN ST SEGMENT ELEVATION MYOCARDIAL INFARCTION

Aim. To evaluate the dynamics of the parameters of autonomic balance and electrical instability of the myocardium depending on the effectiveness of the restoration of coronary blood flow in pharmacoinvasive revascularization in patients with acute ST segment elevation myocardial infarction. Material and methods . The study included 91 patients who underwent effective thrombolytic therapy (TLT) according to the ECG criteria, followed by (3-24 hour later) coronary angiography with percutaneous coronary intervention (PCI). Before and after PCI the telemetric ECG recording was conducted. The dynamics of the temporal and spectral characteristics of heart rate variability (HRV), presence of ventricular late potentials (VLP) and abnormal heart rate turbulence (HRT) were evaluated. Results. The episodes of ST-segment re-elevation by1 mm or more, lasting at least 1 min, and the dynamics of some HRV indices indicated the development of rethrombosis after TLT. The increase in the mean square deviation of normal intervals to 82.5 (64.5; 94) ms, the average value of the standard deviations of normal intervals calculated over 5-minute intervals throughout the entire recording to 37.5 (31.5; 47.5) ms, the total power of the spectrum and the power of high frequency waves, as well as the decrease in the power of ultra-low frequency waves were found after PCI in the group with a rethrombosis of the infarct-related coronary artery. The analysis of VLP in this group showed an increase in duration of the filtered QRS complex after TLT (to 128.7±34.5 ms), and the root mean square value of the last 40 ms of the QRS complex after PCI (to 49±50.3 μV). Pathological deviations of the HRT parameters (especially the onset of turbulence) independently on the absolute values were registered more often in patients with rethrombosis, and abnormal values of both HRT parameters were found only in patients with episodes of unstable coronary blood flow. Conclusion. The results are the indirect evidences of disruption of autonomic regulation of cardiac activity and increased arrhythmic readiness of myocardium in developing rethrombosis of coronary artery. The pronounced reperfusion injury of the myocardium evidently plays an important role in this process and is associated with embolization of the vessels of the microcirculatory bed, release of free radicals and alteration of cardiomyocytes, especially due to prolonged ischemia.

Role of signal-averaged electrocardiography and ventricular late potentials in patients with chronic obstructive pulmonary disease.

Patients with chronic obstructive pulmonary disease (COPD) have an increased risk for cardiac arrhythmias. Ventricular late potentials (VLP) on signal-averaged electrocardiography (SAECG) are associated with an increased risk for malignant ventricular arrhythmias. Our aim is to investigate the modifications of SAECG parameters and the presence of VLP as possible indicators of proarrhythmic substrate in patients with COPD. We prospectively enrolled 41 consecutive patients in the COPD group and 63 patients without any history of pulmonary disease, matched for age and hypertension history, in the control group. Pulmonary function tests, arterial blood gases, echocardiography, 24-hour Holter monitoring and SAECG were performed. We measured total filtered QRS duration (QRSf), duration of high frequency, low-amplitude signals < 40 V (HFLA40), and root mean square voltage in the last 40 ms (RMS40). VLP were considered if at least two of these parameters were abnormal. Results. We did not register any significant differences in QRSf, HFLA40 or RMS40 between the two groups. In the COPD group there was a non-significant higher percentage of patients with VLP in comparison with the control group. In the COPD patients we registered a significantly higher number of isolated premature ventricular beats and of combined complex ventricular arrhythmias, consisting of polymorphic PVC, couplets, triplets or nonsustained ventricular tachycardias. None of these arrhythmic parameters correlated with SAECG variables or with the presence of VLP. Conclusion. In COPD patients parameters measured on signal-averaged electrocardiography and ventricular late potentials analysis have little value in risk stratification for ventricular arrhythmias.

Single Guide League Ventricular Late Potentials Extraction Based on Signal Correlation

The detection and analysis of Ventricular Late Potentials (VLP) is a kind of effective means to predict patients with disease outbreaks clinically and understand ventricular mechanism, single guide league system will become a trend in future medicine. This paper proposes a Blind Source Separation (BSS) method to single guide league observed signal with correlation theory, this method will unify wavelet packet transformation and Independent Component Analysis (ICA), which can fully recover VLP, but the extracted ECG signal has distortion, in order to eliminate distortion, it is necessary to reduce the noises of extracted ECG signal, then the source signals can be estimated accurately. It is proved that the proposed method is effective, and able to solve underdetermined BSS, it can get better separation effect than the traditional FastICA algorithm that the number of source signals is equal to the number of observed signals.

第3回 体表心臓微小電位研究会 健常人における加算平均心電図の検討

第3回 体表心臓微小電位研究会 健常人における加算平均心電図の検討

Analysis of ventricular late potentials in signal-averaged ECG of people with epilepsy

There has been growing interest in cardiac disturbances in epilepsy patients and their etiologic role in the context of sudden death. Ventricular late potentials (VLPs) recorded on signal-averaged electrocardiography (SAECG) reflects delayed ventricular depolarization and identifies the structural or functional substrate for the ventricular tachycardia in the reentry mechanism. Therefore, abnormal SAECG poses the potential of identifying patients at increased risk of malignant ventricular arrhythmias and sudden cardiac death. The aim of this exploratory study was to screen epilepsy patients who were treated with established doses of antiepileptic drugs (AEDs) on the presence of VLPs. Forty-five consecutive patients with the diagnosis of epilepsy and 19 healthy volunteers, aged younger than 46 years, participated in the study. Exclusion criteria included symptoms or signs of diseases other than epilepsy, in particular relating to heart disease or medication influencing the cardiovascular system, as well as seizure reported by patients that occurred <3 days before the ECG examination. The electrocardiogram was recorded according to the standard protocol. The seizure frequency was calculated based on the available data of epileptic events within the preceding 3 months. Disease duration was estimated by determining the time from the first reported seizure to the present. There were 22 patients (48%) in the epilepsy group and only one patient (5%) in the control group fulfilling the criteria for VLP (p = 0.0005). Subsequently, epilepsy patients were divided into two subgroups according to VLP presence. Patients with VLP had longer disease duration (p = 0.03) compared to those without VLP. Similarly, patients with VLP more frequently had refractory epilepsy (p = 0.03) and had higher monthly seizure frequency (p = 0.02). Analysis of the proportions of generalized seizures (GS) and focal seizures (FS) showed a tendency for higher number of generalized tonic-clonic seizures in the VLP group, but this did not reach statistical significance (p = 0.06). VLP patients tended to be more often on polytherapy (defined as more than one AED per patient) (p = 0.07) as compared to epilepsy patients without VLP. However, if the numbers of AEDs per patients among the subgroups were compared, patients with VLP were treated with more AEDs than patients without VLP (p = 0.01). The study was not sufficiently powered to pinpoint any particular drug or AED combination to influence the appearance of VLP in epileptic patients. In particular, there was no difference in valproate or carbamazepine exposure, considering the percentage of patients exposed or the total daily dose administered. Epilepsy patients more frequently display abnormal SAECGs with VLPs as compared to the control population, and their presence correlates with the disease duration, uncontrolled seizures, and polytherapy. Further longitudinal studies are needed in order to stratify the risk of life-threatening ventricular events in epilepsy patients with VLPs.

Iodine-123 metaiodobenzylguanidine myocardial imaging in haemodialysed patients asymptomatic for coronary artery disease

The aim of this study was to evaluate the usefulness of iodine-123 metaiodobenzylguanidine (I-mIBG) myocardial scintigraphy in the detection of cardiac sympathetic neuropathy in haemodialysed patients without relevant cardiovascular symptoms. A group of 20 haemodialysed patients were examined. The stress/rest myocardial perfusion scintigraphy by gated single-photon emission computed tomography was performed. Cardiac sympathetic functions were evaluated by single-photon emission computed tomography and planar I-mIBG myocardial scintigraphy and also by 24-h Holter study, with heart rate variability (HRV) and signal-averaged electrocardiogram analysis of ventricular late potentials. Semiquantitative analysis of I-mIBG myocardial uptake was expressed as routine heart/mediastinum ratio (HMR) 15 [early (eHMR)] and 240 min [delayed (dHMR)] after administration and washout rate (WOR). Myocardial perfusion scintigraphy showed normal values of all parameters, but semiquantitative I-mIBG cardiac imaging assessment indicated low values of HMR (eHMR 1.87±0.27; dHMR 1.74±0.25) and high values of WOR (31.38±9.49) compared with normal values. In 10 patients (50%) ventricular late potential was determined, and in these patients mean values of dHMR came up to 1.59±0.20. The mean value of HRV came up to 88.40±16.05 and significant correlations were found between HRV and eHMR (P=0.01) and dHMR (P=0.007). I-mIBG scintigraphy can detect very early stages of cardiac sympathetic dysfunction. Low values of HMR and high values of WOR suggest an impaired cardiac adrenergic system in patients without any relevant symptoms of heart failure. Low values of HRV may confirm cardiac autonomic neuropathy.

Analysis of Ventricular Late Potentials using wavelets and FFT spectrum

Ventricular Late Potentials (VLPs) are low amplitude, wideband frequency signals that occur in the ventricles. In the classical method of detecting VLPs, the ECG of the patient has to be recorded for about an hour or more. Real-time signal processing is not possible and the doctor has to wait until the whole record (one hour or more) of the patient is obtained. At least 400 beats are required to confirm the presence of VLP. The method proposed in this paper is to analyse the ECG waveform in the frequency domain to detect VLP. Using the proposed method Real time processing is possible for this method, the reason being a single beat can be analysed with simultaneous recording of the next beat. As the processing and recording stages are parallel, the method is very fast in analysing VLPs.

Bivariable analysis of ventricular late potentials in high resolution ECG records

In this study the bivariable analysis for ventricular late potentials detection in high-resolution electrocardiographic records is proposed. The standard time-domain analysis and the application of the time-frequency technique to high-resolution ECG records are briefly described as well as their corresponding results. In the proposed technique the time-domain parameter, QRSD and the most significant time-frequency index, ENQRS are used like variables. A bivariable index is defined, that combines the previous parameters. The propose technique allows evaluating the risk of ventricular tachycardia in post-myocardial infarct patients. The results show that the used bivariable index allows discriminating between the patient's population with ventricular tachycardia and the subjects of the control group. Also, it was found that the bivariable technique obtains a good valuation as diagnostic test. It is concluded that comparatively, the valuation of the bivariable technique as diagnostic test is superior to that of the time-domain method and the time-frequency technique evaluated individually.

Quantitative evaluation of a wavelet-based method in ventricular late potential detection

Ventricular late potentials (VLPs) are low-amplitude, high-frequency waveforms appearing in the terminal part of the QRS complex in electrocardiogram (ECG) of patients who are susceptible to ventricular tachycardia and sudden cardiac death, after surviving myocardial infarction. Accordingly, VLP detection presents a prominent non-invasive marker for some cardiac diseases clinically. This paper proposes a VLP detection method based on the wavelet transform and investigates its performance. In this method, a modified vector magnitude waveform is formed using discrete wavelet transform for each high-resolution ECG (HRECG) record; then, by applying the continuous wavelet transform to the QRS complex end part in this waveform, a feature vector is extracted from the resultant time-scale plot. This wavelet-based feature vector is processed by principle component analysis to reduce its dimensionality. Finally, a supervised feedforward artificial neural network, trained by a proper set of these feature vectors, is employed as a classifier. To evaluate the proposed method performance, a HRECG database consisting of the real VLP-negative and simulated VLP-positive patterns is used. In a comparative approach, different VLP detection techniques including the conventional time-domain method, developed by Simson, and some methods utilizing distinct diagnostic features are also applied to this database to investigate the capability of the proposed method in VLP analysis more completely. The results show the proposed method, employing the wavelet transform in both pre-processing and feature extraction stages, reveals high evaluation criteria (accuracy, sensitivity, and specificity) and is qualified to detect VLPs.

Comparative analysis on wavelet-based detection of finite duration low-amplitude signals related to ventricular late potentials

Ventricular late potentials (VLPs) are considered as a noninvasive marker of patients with myocardial infarction, who are prone to the development of ventricular tachycardia. This paper investigates the effects of variations in physical properties of myocardial infarcts in terms of their effects on the parametric variations in VLP analysis. A sufficiently large set of signals underlining the behavior of physical parameters was employed to represent the effect of physical size, position, orientation and type of infarct. The approximated signals are variations from real electrocardiography signals by adding potentials representing late potentials based on duration, frequency, amplitude and position. The aim is not to exactly model VLP but rather to generate an approximate set of signals to examine the performance of the standard methods for different possibilities in infarct dynamics. We investigate some of the detection approaches together with their related assumptions, and try to pinpoint the drawbacks and inaccuracies of these methods and also their assumptions. The three widely accepted criteria—QRS duration, root-mean-square and duration of the signal at the end of QRS for VLP detection—were used in the investigation. Results from the application of these parameters to the set of signals are presented. In addition we investigate the physical nature of an infarct and list a number of possible reasons that might be the cause of a low success rate for the detection of additive potentials. To improve the performance of the common methods, two more wavelet transform parameters are added to those of the standard methods. The method derived from this analysis is presented as an alternative means for the detection of late signals named as delayed potentials, a more general class that includes VLP as a subset.

Late potential analysis: is a mathematically-derived X,Y,Z lead system comparable to a true orthogonal X,Y,Z lead system?

Analysis of ventricular late potentials (LP) with signal-averaged ECG (SAECG) using three bipolar, orthogonal X,Y, Z leads is a validated method of risk-stratification in patients prone to ventricular tachycardia. The aim of this study was to validate a ECG system, which allows LP analysis using X,Y, Z leads mathematically derived from the standard 12-lead ECG. In 36 patients (age 56 +/- 12 years, coronary artery disease 71%, LVEF 46 +/- 14%) with known or suspected ventricular tachyarrhythmia, two consecutive SAECGs were recorded, one with mathematically derived and another one with true X,Y, Z leads. Time domain measurements with these different lead systems were compared using linear regression analysis and "Bland-Altman" plots. Correlation was good (r = 0.92) for the filtered QRS complex duration, but poor for the terminal QRS amplitude (RMS) and duration (LAS) criteria (r = 0.66 and 0.61, respectively; P < 0.0001). Defining LPS as present if at least two of the three time domain criteria were abnormal, the result matched in 28 (78%), but differed in 8 (22%) patients. SAECG using X,Y, Z leads mathematically derived from the standard 12-lead ECG compared to true bipolar X,Y, Z leads show a close correlation in filtered QRS duration, but can differ considerably in the other time domain measurements, resulting in different interpretation of LP analysis in 22%. Therefore, SAECG registration should currently be performed with true X,Y, Z leads, until the accuracy of other approaches is validated.

Noninvasive risk stratification in inherited arrhythmias

Electrocardiographic risk stratification of patients with inherited arrhythmopathies, such as the long-QT syndrome and Brugada syndrome, is unsatisfactory at present. Changes in ventricular depolarization and repolarization as well as autonomic triggers play a pivotal role in the genesis of malignant tachyarrhythmias in these disorders. However, only sparse data are available regarding the usefulness of autonomic or repolarization markers for identification of patients at potential risk of sudden arrhythmogenic death. Whereas the duration of the QT interval as well as analysis of dispersion of repolarization have been used to risk stratify LQTS patients, analysis of ventricular late potentials seems to be promising in patients with Brugada syndrome. With respect to autonomic risk markers, there are currently not enough data to generally justify their use in either of the two entities. More research is necessary to improve risk stratification in phenotypically "silent" gene carriers.

Single-beat analysis of ventricular late potentials in the surface electrocardiogram using the spectrotemporal pattern recognition algorithm in patients with coronary artery disease.

Post-infarction risk stratification can be ascertained from beat-to-beat variations in ventricular late potentials. However, gaining such information by conventional late potential analysis using signal averaging is still not possible. We therefore developed the spectrotemporal pattern recognition algorithm in order to detect beat-to-beat variations in late potentials. Based on the spectrotemporal pattern recognition algorithm two-dimensional correlation function, the typical spectral pattern of late potentials can be identified in spectrotemporal maps of single beats, even in the presence of noise. Surface electrocardiograms of 385 patients after myocardial infarction (85 with documented sustained ventricular tachycardia (group 1), 100 with fast, polymorphic ventricular tachycardia (> 270 cycles.min-1) or primary ventricular fibrillation (group 2), 200 without ventricular arrhythmias (group 3) and 45 healthy volunteers (group 4), were analysed. The spectrotemporal pattern recognition algorithm detected late potentials in single beats in 89% of group 1 patients, in 79% of group 2, in 22% of group 3 and in 4% of normals. The spectrotemporal pattern recognition algorithm measured late potential frequency and extension of late potentials into the ST segment, which was significantly different between groups 1 and 2. Beat-to-beat variations in late potentials, with respect to frequency and extension into the ST segment, were markedly higher in patients with a history of primary ventricular fibrillation. Single-beat analysis using the spectrotemporal pattern recognition algorithm may improve risk stratification of patients after myocardial infarction, and provides information on patients prone to ventricular fibrillation.

Heart Rate Variability in Time Domain after Acute Myocardial Infarction

These results suggest that analysis of heart rate variability recorded even very early after acute myocardial infarction (1 to 2 days after onset of pain) is feasible in clinical routine and strongly related to subsequent arrhythmic events and cardiac mortality. Decreased HRV is considered not only a marker of impaired vagal activity of the heart but complete autonomic impairment, strongly associated with the degree of myocardial damage. HRV represents the integrated response of the cardiovascular system to a variety of different influences: the plasma level of catecholamines, the baroreflex activation and the direct sympathetic and vagal activity. The HRV profile is dynamic-HRV reduction caused by myocardial damage changes over time presenting a progressive increase up to normality over a 2-month follow-up. The observed early differences between anterior and inferior myocardial infarction disappear later in the healing phase. However, group analysis results of different HRV indices are stabile over time and highly reproducible, but presenting large individual variations. HRV parameters which are adjusted to heart rate (e. g. CV) seemed to be more stabile. The role of HRV analysis in risk stratification of patients after myocardial infarction is strongly related to the actual model of the genesis of ventricular arrhythmias. Multiple experimental and clinical studies described the development of life threatening ventricular arrhythmias as a multifactorial event which can not be described adequately using just one risk parameter for stratification. The arrhythmogenic substrate representing the underlying inhomogeneity of electrical behaviour of adjacent myocardial areas might be detectable by the analysis of ventricular late potentials or frequency disturbances from the signal averaged ECG. The autonomic modulation of this substrate is represented by an altered heart rate variability. Possible trigger factors to initiate arrhythmias in a modulated arrhythmogenic substrate like ventricular premature beats or transient myocardial ischemia can be detected by conventional arrhythmia and ST segment analysis from Holter tapes. The optimized combination of these non-invasive risk predictors together with well known evident clinical risk parameters, like left ventricular ejection fraction, may lead to a valid set of screening parameters for individual risk estimation after myocardial infarction.

Multiresolution decomposition of the signal-averaged ECG using the mallat approach for prediction of arrhythmic events after myocardial infarction

The aim of this study was to analyze the ability of the multiresolution decomposition of the signal-averaged electrocardiogram (ECG) to discriminate between patients who develop life-threatening ventricular arrhythmias after myocardial infarction and those who do not and to compare the predictive values of this approach with those obtained from the analysis of ventricular late potentials in the time domain. Signal-averaged ECGs of 769 prospectively included patients were analyzed. A total of 42 arrhythmic events occurred during the follow-up period. For numerical calculations of wavelet analysis, the total and relative energies of the QRS complex were obtained in seven frequency bands. The combination of the relative energy in the frequency bands 7.8–15.6 Hz and 62.5–125 Hz enhanced statistical performance as compared with the time-domain parameters (positive predictive accuracy, 11.3 vs 8.2%). Combining wavelet transform and time-domain parameters enhanced the predictive values even more (positive predictive accuracy, 14.3%) compared with applying each method alone.

Enhanced ECG Signal‐Averaging Techniques: New Applications and Improved Performance

Background: The signal‐averaged ECG is a widely used and accepted technique for analysis of low‐level cardiac signals. This article reviews a new and enhanced form of ECG signal averaging: the time‐frequency plane Wiener (TFPW) filter.Methods: The TFPW filter accelerates the process of noise reduction. It facilitates use of signal averaging in settings previously unexplored with the technique, where a limited number of beats may be available.Conclusion: Example applications of the TFPW filter include improved analysis of ventricular late potentials and analysis of dynamic events, such as transient ischemia.

Standards for analysis of ventricular late potentials using high resolution or signal-averaged electrocardiography

Sufficient data are available to recommend that the high-resolution or signal-averaged electrocardiogram can be used in patients recovering from myocardial infarction without bundle branch block to help to determine their risk for developing sustained ventricular tachyarrhythmias. However, no data are available regarding the extent to which pharmacologic or non-pharmacologic interventions in patients with late potentials have an impact on the incidence of sudden cardiac death. Therefore, controlled, prospective studies are required before this issue can be definitely answered. As refinements in techniques evolve, it is anticipated that the clinical value of high-resolution or signal-averaged electrocardiography will continue to increase in the future.

Standards for analysis of ventricular late potentials using high-resolution or signal-averaged electrocardiography: A statement by a task force committee of the European Society of Cardiology, the American Heart Association, and the American College of Cardiology

Sufficient data are available to recommend the use of the high-resolution or signal-averaged electrocardiogram in patients recovering from myocardial infarction without bundle branch block to help determine their risk for developing sustained ventricular tachyarrhythmias. However, no data are available about the extent to which pharmacological or nonpharmacological interventions in patients with late potentials have an impact on the incidence of sudden cardiac death. Therefore, controlled, prospective studies are required before this issue can be resolved. As refinements in techniques evolve, it is anticipated that the clinical value of high-resolution or signal-averaged electrocardiography will continue to increase.

Standards for analysis of ventricular late potentials using high-resolution or signal-averaged electrocardiography. A statement by a Task Force Committee of the European Society of Cardiology, the American Heart Association, and the American College of Cardiology.

Sufficient data are available to recommend the use of the high-resolution or signal-averaged electrocardiogram in patients recovering from myocardial infarction without bundle branch block to help determine their risk for developing sustained ventricular tachyarrhythmias. However, no data are available about the extent to which pharmacological or nonpharmacological interventions in patients with late potentials have an impact on the incidence of sudden cardiac death. Therefore, controlled, prospective studies are required before this issue can be resolved. As refinements in techniques evolve, it is anticipated that the clinical value of high-resolution or signal-averaged electrocardiography will continue to increase.