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Arrhythmia & Electrophysiology Review May 2016Microvolt T-wave alternans (TWA), characterised as beat-to-beat fluctuation of T-wave amplitude and morphology, is an electrophysiological phenomenon associated...
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. Although TWA appears to be a useful marker of susceptibility for lethal ventricular arrhythmias and cardiovascular death, so far there is no sufficient evidence from randomised clinical trials to support its use in guiding therapy. However, several ongoing trials are expected to provide more information about the clinical use of TWA testing.
PubMed: 27403292
DOI: 10.15420/aer.2015.28.1 -
Sensors (Basel, Switzerland) Sep 2015We present a small and lightweight fully wireless optogenetic headstage capable of optical neural stimulation and electrophysiological recording. The headstage is...
We present a small and lightweight fully wireless optogenetic headstage capable of optical neural stimulation and electrophysiological recording. The headstage is suitable for conducting experiments with small transgenic rodents, and features two implantable fiber-coupled light-emitting diode (LED) and two electrophysiological recording channels. This system is powered by a small lithium-ion battery and is entirely built using low-cost commercial off-the-shelf components for better flexibility, reduced development time and lower cost. Light stimulation uses customizable stimulation patterns of varying frequency and duty cycle. The optical power that is sourced from the LED is delivered to target light-sensitive neurons using implantable optical fibers, which provide a measured optical power density of 70 mW/mm² at the tip. The headstage is using a novel foldable rigid-flex printed circuit board design, which results into a lightweight and compact device. Recording experiments performed in the cerebral cortex of transgenic ChR2 mice under anesthetized conditions show that the proposed headstage can trigger neuronal activity using optical stimulation, while recording microvolt amplitude electrophysiological signals.
Topics: Animals; Brain-Computer Interfaces; Electrodes, Implanted; Electrophysiology; Equipment Design; Mice; Microelectrodes; Optogenetics; Telemetry; Wireless Technology
PubMed: 26371006
DOI: 10.3390/s150922776 -
Cardiovascular Digital Health Journal Aug 2022Qualitative differences in 12-lead electrocardiograms (ECG) at onset have been reported in patients with takotsubo syndrome (TTS) and acute anterior myocardial...
BACKGROUND
Qualitative differences in 12-lead electrocardiograms (ECG) at onset have been reported in patients with takotsubo syndrome (TTS) and acute anterior myocardial infarction (Ant-AMI). We aimed to distinguish these diseases by machine learning (ML) approach of microvolt-level quantitative measurements.
METHODS
We enrolled 56 consecutive patients with sinus rhythm TTS (median age, 77 years; 16 men), and 1-to-1 random matching was performed based on age and sex of the patients. The ECG in the emergency room was evaluated using an automated system (ECAPs12c; Nihon-Koden). Statistical and ML predictive models for TTS were constructed using clinical features and ECG parameters.
RESULTS
Statistically significant differences were observed in 25 parameters; the V ST level at the J point (V STJ) showed the lowest value ( < .001). V STJ ≤+18 μV showed the highest accuracy for TTS (0.773). The highest area under the receiver operating characteristic curve (AUROC) was shown in the aVR ST level at 1/16th of the preceding R-R interval after the J point (aVR STmid: 0.727). Conversely, the light gradient boosting machine (model_LGBM) and extra tree classifier (model_ET) indicated higher accuracy (model_LGBM: 0.842, model_ET: 0.831) and AUROC (model_LGBM: 0.868, model_ET 0.896) than other statistical models. V STJ had high feature importance and Shapley additive explanation values in the 2 ML models.
CONCLUSION
ML applied to automated microvolt-level ECG measurements showed the possibility of distinguishing between TTS and Ant-AMI, which may be a clinically useful ECG-based discriminator.
PubMed: 36046427
DOI: 10.1016/j.cvdhj.2022.07.001 -
Circulation. Arrhythmia and... Dec 2014Prophylactic defibrillator implantation is recommended in dilated, nonischemic heart disease and left ventricular ejection fraction of ≤0.30 to 0.35. Noninvasive... (Observational Study)
Observational Study
BACKGROUND
Prophylactic defibrillator implantation is recommended in dilated, nonischemic heart disease and left ventricular ejection fraction of ≤0.30 to 0.35. Noninvasive testing should improve accuracy in decision making of prophylactic defibrillator implantation.
METHODS AND RESULTS
We enrolled 60 patients (median age, 57 years) with dilated cardiomyopathy and left ventricular ejection fraction ≤0.50, and 30 control subjects (median age, 59 years) with left ventricular ejection fraction >0.50. The protocol included an initial assessment, a second assessment after 3 years, and a final follow-up: pharmacological baroreflex testing (baroreceptor reflex sensitivity), short-term spectral analysis of heart rate variability (low frequency/high frequency), and long-term time domain analysis (SD of all normal-to-normal R-R intervals), exercise microvolt T wave alternans, and signal-averaged ECG, and corrected QT-time. The median follow-up was 7 years. End points were cardiac death, resuscitated cardiac arrest, and arrhythmic death. Cardiac death was observed in 21 patients. Resuscitated cardiac arrest and arrhythmic death caused by ventricular tachyarrhythmias ≥240 per minute was observed in 7 and 10 patients, respectively. In the single time point analysis, microvolt T wave alternans, baroreceptor reflex sensitivity, and SD of all normal-to-normal R-R intervals at initial testing added significant information regarding cardiac death. Microvolt T wave alternans added information on resuscitated cardiac arrest or arrhythmic death at multiple time points (P<0.001). False-negative microvolt T wave alternans results were seen in 8% of patients.
CONCLUSIONS
Noninvasive testing and left ventricular ejection fraction could not reliably identify patients with dilated cardiomyopathy at risk of fatal ventricular tachyarrhythmias. Therefore, the strategy to confine prophylactic implantable cardioverter-defibrillator implantation to patients with dilated cardiomyopathy and severely reduced LV function should be reconsidered.
Topics: Aged; Autonomic Nervous System; Baroreflex; Blood Pressure; Cardiomyopathy, Dilated; Case-Control Studies; Death, Sudden, Cardiac; Decision Support Techniques; Defibrillators, Implantable; Electric Countershock; Electrocardiography; Female; Heart Rate; Humans; Male; Middle Aged; Patient Selection; Predictive Value of Tests; Primary Prevention; Prospective Studies; Risk Assessment; Risk Factors; Stroke Volume; Time Factors; Ventricular Function, Left; Young Adult
PubMed: 25262115
DOI: 10.1161/CIRCEP.114.001745 -
Stomatologija 2017The aim of this study was to investigate muscular function and mandibular kinesiology of patients undergoing orthodontic-surgical treatment by electromyography and...
INTRODUCTION
The aim of this study was to investigate muscular function and mandibular kinesiology of patients undergoing orthodontic-surgical treatment by electromyography and kinesiography. Electromyographic evaluation is essential to estimate masticatory forces in patients undergoing combined surgical-orthodontic treatment.
MATERIALS AND METHODS
60 patients referred for orthodontic surgical treatment were included in the study, 43 patients presented a class III while 17 presented a class II. The patients underwent electromyographic and kinesiographic examinations during all the therapeutic orthodontic-surgical phases.
RESULTS
The relationship between fundamental electromyographic values and age, weight, asymmetry and activation was weak. A strong and positive relationship was observed between the relaxation percentage after TENS (transcutaneous electrical neuromuscular stimulation), the steepness of the post-surgery rehabilitation curve, the initial POC (percentage overlapping coefficient), and for the values in microvolts of the right and left temporal and masseters at the beginning of treatment.
CONCLUSIONS
Patients with dentofacial deformities corrected by surgical treatment, have a significant positive treatment outcome in respect of masticatory activity and performance electromyographic evaluation on, before, during and follow up period of the analized patients permit to underline that this examination can predict long term stability.
Topics: Adult; Biomechanical Phenomena; Combined Modality Therapy; Electromyography; Female; Follow-Up Studies; Humans; Male; Malocclusion, Angle Class II; Malocclusion, Angle Class III; Mandible; Orthodontics, Corrective; Orthognathic Surgical Procedures; Time Factors
PubMed: 29243682
DOI: No ID Found -
Journal of Arrhythmia Apr 2021Early detection of cardiac involvement in patients with sarcoidosis is important but currently unresolved. The aim of this study was to elucidate the utility of...
BACKGROUND
Early detection of cardiac involvement in patients with sarcoidosis is important but currently unresolved. The aim of this study was to elucidate the utility of frequency domain microvolt T-wave alternans (TWA), signal-averaged ECG (SAECG), and heart rate turbulence (HRT) using 24-hour Holter ECG for detecting cardiac involvement in patients with pulmonary sarcoidosis.
METHODS
This study consisted of consecutive 40 pulmonary sarcoidosis patients (11 males, 62 ± 13 years) who underwent 24-hour Holter monitoring with and without cardiac involvement. All patients underwent frequency domain TWA, SAECG, and HRT using 24-hour Holter monitoring. Patients with atrial fibrillation pacing or wide QRS electrocardiogram were excluded.
RESULTS
After 14 patients were excluded, a total of 26 patients (six males, 59 ± 14 years) were evaluated. Seven patients had cardiac involvement (cardiac sarcoidosis [CS] group). On the Holter SAECG, duration of low-amplitude signals <40 μV in the terminal filtered QRS complex (LAS40) was significantly higher, and root mean square voltage of the terminal 40 ms of the filtered QRS complex (RMS40) was significantly lower in the CS group compared with the non-CS group (LAS40: 61.4 ± 35.9 vs 37.6 ± 9.2 ms; = .018, RMS40: 11.4 ± 10.3 vs 23.6 ± 13.2 ms; = .023). Prevalence of positive late potential (LP) was also significantly higher in the CS group than that in the non-CS group (85.7% vs 31.5%; = .026). The sensitivity, specificity, positive, and negative predictive values of LP for identifying patients with cardiac involvement were 85.7%, 68.4%, 50.0%, and 92.8%, respectively.
CONCLUSION
Holter SAECG may be useful for detecting cardiac involvement in patients with pulmonary sarcoidosis.
PubMed: 33850586
DOI: 10.1002/joa3.12501 -
PloS One 2018Pulmonary arterial hypertension (PAH) is a rare disorder with unfavorable prognosis despite implementation of specific PAH-oriented therapy. The aim of the study was to... (Observational Study)
Observational Study
OBJECTIVES
Pulmonary arterial hypertension (PAH) is a rare disorder with unfavorable prognosis despite implementation of specific PAH-oriented therapy. The aim of the study was to define predictors of poor prognosis in patients from one center treated according to the Polish National Health Fund program.
PATIENTS AND METHODS
Forty-seven consecutive patients (30 women; aged 39±17 years) with PAH diagnosis were enrolled to the study. Clinical assessment, laboratory measurements, electrocardiogram, echocardiography, 6-minute walk test, 24-hour Holter monitoring, cardiopulmonary exercise test and microvolt T-wave alternans test were performed during routine visits. Eight patients died during 2.6±1.7 years follow-up.
RESULTS
Parametrs which differentiated patients who died were brain natriuretic peptide (BNP) concentration ≥330 pg/mL (sensitivity 88%, specificity 92%, area under the ROC curve [AUC] 0.92); bilirubin concentration ≥1.2 mg/dL (sensitivity 88%, specificity 81%, AUC 0.85); right atrial area ≥21 cm2 (sensitivity 86%, specificity 69%, AUC 0.84), right ventricular (RV) dimension in the apical 4-chamber view ≥47 mm (sensitivity 86%, specificity 86%, AUC 0.85) and RV to left ventricular diastolic diameter ratio ≥1.5 (sensitivity 83%, specificity 84%; AUC 0.85). In multivariate analysis, independent predictors of mortality were higher BNP (p = 0.04) and bilirubin level (p = 0.03), higher right atrial area (p = 0.02) and lower tricuspid annular plane systolic excursion (p = 0.03).
CONCLUSIONS
In PAH patients treated with specific PAH-oriented therapy right atrial enlargement, impaired right ventricular systolic function, as well as increased BNP and bilirubin concentration was associated with an increased mortality risk.
Topics: Adult; Echocardiography; Exercise Test; Female; Heart; Humans; Hypertension, Pulmonary; Male; Middle Aged; Prospective Studies; ROC Curve
PubMed: 29684090
DOI: 10.1371/journal.pone.0193245 -
IEEE Transactions on Biomedical... Oct 2016We present a bidirectional neural interface with a 4-channel biopotential analog-to-digital converter (bioADC) and a 4-channel current-mode stimulator in 180 nm CMOS....
We present a bidirectional neural interface with a 4-channel biopotential analog-to-digital converter (bioADC) and a 4-channel current-mode stimulator in 180 nm CMOS. The bioADC directly transduces microvolt biopotentials into a digital representation without a voltage-amplification stage. Each bioADC channel comprises a continuous-time first-order ∆Σ modulator with a chopper-stabilized OTA input and current feedback, followed by a second-order comb-filter decimator with programmable oversampling ratio. Each stimulator channel contains two independent digital-to-analog converters for anodic and cathodic current generation. A shared calibration circuit matches the amplitude of the anodic and cathodic currents for charge balancing. Powered from a 1.5 V supply, the analog and digital circuits in each recording channel draw on average [Formula: see text] and [Formula: see text] of supply current, respectively. The bioADCs achieve an SNR of [Formula: see text] and a SFDR of [Formula: see text] , for better than 9-b ENOB. Intracranial EEG recordings from an anesthetized rat are shown and compared to simultaneous recordings from a commercial reference system to validate performance in-vivo . Additionally, we demonstrate bidirectional operation by recording cardiac modulation induced through vagus nerve stimulation, and closed-loop control of cardiac rhythm. The micropower operation, direct digital readout, and integration of electrical stimulation circuits make this interface ideally suited for closed-loop neuromodulation applications.
Topics: Amplifiers, Electronic; Analog-Digital Conversion; Electric Stimulation Therapy; Equipment Design; Equipment Failure Analysis; Implantable Neurostimulators; Miniaturization; Signal Processing, Computer-Assisted
PubMed: 27845676
DOI: 10.1109/TBCAS.2016.2614845 -
Cognitive Neurodynamics Oct 2017Post-mortem human neural tissues fixed in ethanol and aldehyde-based solutions express modulated frequency-dependent microvolt potentials when probed by chemical and...
Post-mortem human neural tissues fixed in ethanol and aldehyde-based solutions express modulated frequency-dependent microvolt potentials when probed by chemical and electrical stimuli. These observations run contrary to the assumption that basic tissue functions are irreversibly impaired upon fixation, in the absence of nutrients and sufficient concentrations of physiological ions. The aim of the current study was to investigate the relative effects of pH and specific charged particles relevant to normal cell physiology upon electric potentials associated with fixed post-mortem rat brain tissue. We identified a positive relationship between the total time the brains had been immersed in ethanol-formalin-acetic acid and high-frequency microvolt potentials within the dorsal right hemisphere of the rat cerebrum. Measuring the pH of the fixative solution surrounding the brains indicated that as time increased, a logarithmic trend toward alkalinity could be observed. Further experiments revealed that high-frequency microvolt potentials were related to pH changes within the right hemisphere only. The right ventral cerebrum displayed a unique response to potassium chloride in ways uncounted for by pH alone. The results suggest that the fixed post-mortem right cerebrum of the rat is particularly sensitive to pH and physiological ions which explains a subset of previous findings with respect to stimulus-response patterns in human coronal brain sections. A concluding hypothesis is presented which suggests that brain tissue expresses material properties independent of metabolic activity though perhaps relevant to living brain function.
PubMed: 29067131
DOI: 10.1007/s11571-017-9443-3 -
Data in Brief Oct 2023Biomedical Electroencephalography (EEG) signals are the result of measuring the electric potential difference generated on the scalp surface by neural activity...
Biomedical Electroencephalography (EEG) signals are the result of measuring the electric potential difference generated on the scalp surface by neural activity corresponding to each brain area. Accurate and automatic detection of neural activity from the upper and lower limbs using EEG may be helpful in rehabilitating people suffering from mobility limitations or disabilities. This article presents a dataset containing 7440 CSV files from 60 test subjects during motor and motor imagery tasks. The motor and motor imagery tasks performed by the test subjects were: Closing Left Hand (CLH), Closing Right Hand (CRH), Dorsal flexion of Left Foot (DLF), Plantar flexion of Left Foot (PLF), Dorsal flexion of Right Foot (DRF), Plantar flexion of Right Foot (PRF) and Resting in between tasks (Rest). The volunteers were recruited from research colleagues at ESPOL and patients at the Luis Vernaza Hospital in Guayaquil, Ecuador. Each CSV file has 501 rows, of which the first one lists the electrodes from 0 to 15, and the remaining 500 rows correspond to 500 data recorded during the task is performed due to sample rate. In addition, each file has 17 columns, of which the first one indicates the sampling number and the remaining 16 columns represent 16 surface EEG electrodes. As a data recording equipment, the OpenBCI is used in a monopolar setup with a sampling rate of 125 Hz. This work includes statistical measures about the demographic information of all recruited test subjects. Finally, we outline the experimental methodology used to record EEG signals during upper and lower limb task execution. This dataset is called MILimbEEG and contains microvolt (µV) EEG signals acquired during motor and motor imagery tasks. The collected data may facilitate the evaluation of EEG signal detection and classification models dedicated to task recognition.
PubMed: 37727590
DOI: 10.1016/j.dib.2023.109540