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Otolaryngology--head and Neck Surgery :... Aug 2022Electrocochleography (ECochG) is increasingly being used during cochlear implant (CI) surgery to detect and mitigate insertion-related intracochlear trauma, where a drop...
OBJECTIVE
Electrocochleography (ECochG) is increasingly being used during cochlear implant (CI) surgery to detect and mitigate insertion-related intracochlear trauma, where a drop in ECochG signal has been shown to correlate with a decline in hearing outcomes. In this study, an ECochG-guided robotics-assisted CI insertion system was developed and characterized that provides controlled and consistent electrode array insertions while monitoring and adapting to real-time ECochG signals.
STUDY DESIGN
Experimental research.
SETTING
A research laboratory and animal testing facility.
METHODS
A proof-of-concept benchtop study evaluated the ability of the system to detect simulated ECochG signal changes and robotically adapt the insertion. Additionally, the ECochG-guided insertion system was evaluated in a pilot in vivo sheep study to characterize the signal-to-noise ratio and amplitude of ECochG recordings during robotics-assisted insertions. The system comprises an electrode array insertion drive unit, an extracochlear recording electrode module, and a control console that interfaces with both components and the surgeon.
RESULTS
The system exhibited a microvolt signal resolution and a response time <100 milliseconds after signal change detection, indicating that the system can detect changes and respond faster than a human. Additionally, animal results demonstrated that the system was capable of recording ECochG signals with a high signal-to-noise ratio and sufficient amplitude.
CONCLUSION
An ECochG-guided robotics-assisted CI insertion system can detect real-time drops in ECochG signals during electrode array insertions and immediately alter the insertion motion. The system may provide a surgeon the means to monitor and reduce CI insertion-related trauma beyond manual insertion techniques for improved CI hearing outcomes.
Topics: Animals; Audiometry, Evoked Response; Cochlea; Cochlear Implantation; Cochlear Implants; Craniocerebral Trauma; Hearing; Humans; Labyrinth Diseases; Sheep
PubMed: 34609909
DOI: 10.1177/01945998211049210 -
Journal of Cardiovascular Development... Jan 2023Atrial fibrillation (AF) is the most persistent arrhythmia today, with its prevalence increasing exponentially with the rising age of the population. Particularly at... (Review)
Review
Atrial fibrillation (AF) is the most persistent arrhythmia today, with its prevalence increasing exponentially with the rising age of the population. Particularly at elevated heart rates, a functional abnormality known as cardiac alternans can occur prior to the onset of lethal arrhythmias. Cardiac alternans are a beat-to-beat oscillation of electrical activity and the force of cardiac muscle contraction. Extensive evidence has demonstrated that microvolt T-wave alternans can predict ventricular fibrillation vulnerability and the risk of sudden cardiac death. The majority of our knowledge of the mechanisms of alternans stems from studies of ventricular electrophysiology, although recent studies offer promising evidence of the potential of atrial alternans in predicting the risk of AF. Exciting preclinical and clinical studies have demonstrated a link between atrial alternans and the onset of atrial tachyarrhythmias. Here, we provide a comprehensive review of the clinical utility of atrial alternans in identifying the risk and guiding treatment of AF.
PubMed: 36826532
DOI: 10.3390/jcdd10020036 -
Journal of the American Heart... Sep 2020Background Action potential alternans can induce ventricular tachyarrhythmias and manifest on the surface ECG as T-wave alternans (TWA) and QRS alternans (QRSA). We...
Background Action potential alternans can induce ventricular tachyarrhythmias and manifest on the surface ECG as T-wave alternans (TWA) and QRS alternans (QRSA). We sought to evaluate microvolt QRSA in cardiomyopathy patients in relation to TWA and ventricular tachyarrhythmia outcomes. Methods and Results Prospectively enrolled cardiomyopathy patients (n=100) with prophylactic defibrillators had 12-lead ECGs recorded during ventricular pacing from 100 to 120 beats/min. QRSA and TWA were quantified in moving 128-beat segments using the spectral method. Segments were categorized as QRSA positive (QRSA+) and/or TWA positive (TWA+) based on ≥2 precordial leads having alternans magnitude >0 and signal:noise >3. Patients were similarly categorized based on having ≥3 consecutive segments with alternans. TWA+ and QRSA+ occurred together in 31% of patients and alone in 18% and 14% of patients, respectively. Although TWA magnitude (1.4±0.4 versus 4.7±1.0 µV, <0.01) and proportion of TWA+ studies (16% versus 46%, <0.01) increased with rate, QRSA did not change. QRS duration was longer in QRSA+ than QRSA-negative patients (138±23 versus 113±26 ms, <0.01). At 3.5 years follow-up, appropriate defibrillator therapy or sustained ventricular tachyarrhythmia was greater in QRSA+ than QRSA-negative patients (30% versus 8%, =0.02) but similar in TWA+ and TWA-negative patients. Among QRSA+ patients, the event rate was greater in those without TWA (62% versus 21%, =0.02). Multivariable Cox analysis revealed QRSA+ (hazard ratio [HR], 4.6; 95% CI, 1.5-14; =0.009) and QRS duration >120 ms (HR, 4.1; 95% CI, 1.3-12; =0.014) to predict events. Conclusions Microvolt QRSA is novel phenomenon in cardiomyopathy patients that can exist without TWA and is associated with QRS prolongation. QRSA increases the risk of ventricular tachyarrhythmia 4-fold, which merits further study as a risk stratifier.
Topics: Aged; Algorithms; Arrhythmias, Cardiac; Canada; Cardiomyopathies; Case-Control Studies; Defibrillators, Implantable; Electrocardiography; Female; Heart Ventricles; Humans; Male; Middle Aged; Noise; Prospective Studies; Risk Factors; Tachycardia, Ventricular
PubMed: 32806990
DOI: 10.1161/JAHA.119.016461 -
Minerva Cardioangiologica Apr 2019The QT interval along with its heart rate corrected form (QTc) are well-established ECG markers that have been found to be associated with malignant ventricular... (Review)
Review
The QT interval along with its heart rate corrected form (QTc) are well-established ECG markers that have been found to be associated with malignant ventricular arrhythmogenesis. However, extensive preclinical and clinical investigations over the years have allowed for novel clinical ECG markers to be generated as predictors of arrhythmogenesis and sudden cardiac death. Repolarization markers include the older QTc, QT dispersion and newer Tpeak - Tend intervals, (Tpeak - Tend) / QT ratios, T-wave alternans (TWA), microvolt TWA and T-wave area dispersion. Meanwhile, conduction markers dissecting the QRS complex, such as QRS dispersion (QRSD) and fragmented QRS, were also found to correlate conduction velocity and unidirectional block with re-entrant substrates in various cardiac conditions. Both repolarization and conduction parameters can be combined into the excitation wavelength (λ). A surrogate marker for λ is the index of Cardiac Electrophysiological Balance (iCEB: QT / QRSd). Other markers based on conduction-repolarization are [QRSD x (Tpeak-Tend) / QRSd] and [QRSD x (Tpeak-Tend) / (QRSd x QT)]. Advancement in technology permitted sophisticated electrophysiological analyses such as principal component analysis and periodic repolarization dynamics to further improve risk stratification. This was closely followed by other novel indices including ventricular ectopic QRS interval, the f99 index and EntropyXQT, which integrates mathematical and physical calculations for determining the risk markers. Though proven to be effective in limited patient cohorts, more clinical studies across different cardiac pathologies are required to confirm their validity. As such, this review seeks to encapsulate the development of old and new ECG markers along with their associated utility and shortcomings in clinical practice.
Topics: Arrhythmias, Cardiac; Biomarkers; Death, Sudden, Cardiac; Electrocardiography; Electrophysiologic Techniques, Cardiac; Heart Rate; Humans; Risk Assessment; Risk Factors
PubMed: 30260143
DOI: 10.23736/S0026-4725.18.04775-8 -
High Blood Pressure & Cardiovascular... Oct 2020Atrial fibrillation (AF) is the most common cardiac arrhythmia. Pharmacologic and non-pharmacologic rhythm control strategies impact on AF-related symptoms, while... (Review)
Review
Atrial fibrillation (AF) is the most common cardiac arrhythmia. Pharmacologic and non-pharmacologic rhythm control strategies impact on AF-related symptoms, while leaving largely unaffected the risk of stroke. Moreover, up to 20% of AF patients are asymptomatic during paroxysmal relapses of arrhythmia, thus underlying the need for early markers to identify at-risk patients and prevent cerebrovascular accidents. Indeed, non-invasive assessment of pre-clinical substrate changes that predispose to AF could provide early identification of at-risk patients and allow for tailored care paths. ECG-derived P wave analysis is a simple-to-use and inexpensive tool that has been successfully employed to detect AF-associated structural and functional atrial changes. Beyond standard electrocardiographic techniques, high resolution signal averaged electrocardiography (SAECG), by recording microvolt amplitude atrial signals, allows more accurate analysis of the P wave and possibly AF risk stratification. This review focuses on the evidence that support P wave analysis to assess AF substrates, predict arrhythmia relapses and guide rhythm-control interventions.
Topics: Action Potentials; Anti-Arrhythmia Agents; Atrial Fibrillation; Cardiac Pacing, Artificial; Catheter Ablation; Electrocardiography; Heart Conduction System; Heart Rate; Humans; Predictive Value of Tests; Recurrence; Signal Processing, Computer-Assisted; Time Factors; Treatment Outcome
PubMed: 32451990
DOI: 10.1007/s40292-020-00390-1 -
Europace : European Pacing,... Apr 2017Microvolt-level T-wave alternans (TWA) assessed by spectral method during an exercise stress test has been widely studied for risk stratification. Several studies have... (Review)
Review
Microvolt-level T-wave alternans (TWA) assessed by spectral method during an exercise stress test has been widely studied for risk stratification. Several studies have documented the association of a positive TWA with total mortality and arrhythmic events. Nevertheless, the need to achieve an elevated and stabilized heart rate resulting in a considerable proportion of indeterminate test results constitutes one of the main limitations of this method. It is well recognized that arrhythmic events may be triggered not only by physical but also by mental stress and are not necessarily associated with exercise. Detection of TWA in ambulatory electrocardiogram recordings during daily activities might be a valuable option in risk stratification. This review describes the modified moving average (MMA) technique for detection of TWA and summarizes the results of clinical studies on the prognostic value of MMA-TWA. So far, MMA-TWA has been studied in over 5000 patients including those evaluated during exercise as well as during daily activities with ambulatory ECG recordings. The results of these studies indicate that increased MMA-TWA is associated with higher risk of cardiac mortality and arrhythmic events.
Topics: Action Potentials; Activities of Daily Living; Arrhythmias, Cardiac; Electrocardiography, Ambulatory; Exercise Test; Heart Conduction System; Heart Rate; Humans; Predictive Value of Tests; Prognosis; Risk Assessment; Risk Factors; Signal Processing, Computer-Assisted
PubMed: 28339589
DOI: 10.1093/europace/euw292 -
Annals of Intensive Care Mar 2022To assess in comatose patients after cardiac arrest (CA) if amplitudes of two somatosensory evoked potentials (SSEP) responses, namely, N20-baseline (N20-b) and N20-P25,...
BACKGROUND
To assess in comatose patients after cardiac arrest (CA) if amplitudes of two somatosensory evoked potentials (SSEP) responses, namely, N20-baseline (N20-b) and N20-P25, are predictive of neurological outcome.
METHODS
Monocentric prospective study in a tertiary cardiac center between Nov 2019 and July-2021. All patients comatose at 72 h after CA with at least one SSEP recorded were included. The N20-b and N20-P25 amplitudes were automatically measured in microvolts (µV), along with other recommended prognostic markers (status myoclonus, neuron-specific enolase levels at 2 and 3 days, and EEG pattern). We assessed the predictive value of SSEP for neurologic outcome using the best Cerebral Performance Categories (CPC1 or 2 as good outcome) at 3 months (main endpoint) and 6 months (secondary endpoint). Specificity and sensitivity of different thresholds of SSEP amplitudes, alone or in combination with other prognostic markers, were calculated.
RESULTS
Among 82 patients, a poor outcome (CPC 3-5) was observed in 78% of patients at 3 months. The median time to SSEP recording was 3(2-4) days after CA, with a pattern "bilaterally absent" in 19 patients, "unilaterally present" in 4, and "bilaterally present" in 59 patients. The median N20-b amplitudes were different between patients with poor and good outcomes, i.e., 0.93 [0-2.05]µV vs. 1.56 [1.24-2.75]µV, respectively (p < 0.0001), as the median N20-P25 amplitudes (0.57 [0-1.43]µV in poor outcome vs. 2.64 [1.39-3.80]µV in good outcome patients p < 0.0001). An N20-b > 2 µV predicted good outcome with a specificity of 73% and a moderate sensitivity of 39%, although an N20-P25 > 3.2 µV was 93% specific and only 30% sensitive. A low voltage N20-b < 0.88 µV and N20-P25 < 1 µV predicted poor outcome with a high specificity (sp = 94% and 93%, respectively) and a moderate sensitivity (se = 50% and 66%). Association of "bilaterally absent or low voltage SSEP" patterns increased the sensitivity significantly as compared to "bilaterally absent" SSEP alone (se = 58 vs. 30%, p = 0.002) for prediction of poor outcome.
CONCLUSION
In comatose patient after CA, both N20-b and N20-P25 amplitudes could predict both good and poor outcomes with high specificity but low to moderate sensitivity. Our results suggest that caution is needed regarding SSEP amplitudes in clinical routine, and that these indicators should be used in a multimodal approach for prognostication after cardiac arrest.
PubMed: 35290522
DOI: 10.1186/s13613-022-00999-6 -
Nature May 2020Thermoelectric generation using the anomalous Nernst effect (ANE) has great potential for application in energy harvesting technology because the transverse geometry of...
Thermoelectric generation using the anomalous Nernst effect (ANE) has great potential for application in energy harvesting technology because the transverse geometry of the Nernst effect should enable efficient, large-area and flexible coverage of a heat source. For such applications to be viable, substantial improvements will be necessary not only for their performance but also for the associated material costs, safety and stability. In terms of the electronic structure, the anomalous Nernst effect (ANE) originates from the Berry curvature of the conduction electrons near the Fermi energy. To design a large Berry curvature, several approaches have been considered using nodal points and lines in momentum space. Here we perform a high-throughput computational search and find that 25 percent doping of aluminium and gallium in alpha iron, a naturally abundant and low-cost element, dramatically enhances the ANE by a factor of more than ten, reaching about 4 and 6 microvolts per kelvin at room temperature, respectively, close to the highest value reported so far. The comparison between experiment and theory indicates that the Fermi energy tuning to the nodal web-a flat band structure made of interconnected nodal lines-is the key for the strong enhancement in the transverse thermoelectric coefficient, reaching a value of about 5 amperes per kelvin per metre with a logarithmic temperature dependence. We have also succeeded in fabricating thin films that exhibit a large ANE at zero field, which could be suitable for designing low-cost, flexible microelectronic thermoelectric generators.
PubMed: 32376952
DOI: 10.1038/s41586-020-2230-z -
Biological Psychology Jan 2024In behavioral studies, facial electromyographic (EMG) responses to external stimuli or internal events are usually quantified relative to the resting state, presumed to...
In behavioral studies, facial electromyographic (EMG) responses to external stimuli or internal events are usually quantified relative to the resting state, presumed to represent a neutral baseline condition. In the large majority of recent studies, EMG responses were expressed as a difference score in terms of microvolts with the resting state. We argue that since EMG activity is measured on a ratio scale rather than on an interval scale, percentage scores should be used instead of difference scores. Reanalyzing results from an earlier study on the relationships between facial EMG responses and affective empathic responses to emotional video clips, we found that the two different types of EMG response quantification were differently related to affective empathy. Relationships between EMG responses and affective empathy were more consistent or stronger for percentage scores than for difference scores. In another study, facial EMG mimicry responses to pictures of emotional facial expressions were stronger for percentage scores than for difference scores. The adequacy of percentage scores relative to difference scores as indices of psychological variables may be simply checked by comparing both types of scores.
Topics: Humans; Facial Muscles; Electromyography; Emotions; Empathy; Facial Expression; Reference Standards
PubMed: 38134999
DOI: 10.1016/j.biopsycho.2023.108737 -
Journal of Electrocardiology 2018Microvolt T-wave alternans (TWA) is known to be useful in prediction of ischemia and sudden death in high-risk populations and there are no studies in children with...
INTRODUCTION
Microvolt T-wave alternans (TWA) is known to be useful in prediction of ischemia and sudden death in high-risk populations and there are no studies in children with chronic renal failure (CRF). Cardiac problems seem to be responsible for an important part of death in children and young adults with CRF. The aim of this study is to evaluate Holter microvolts TWA measurements in children with CRF comparing to the control group.
METHODS
This prospective study included 40 patients with CRF and 48 healthy controls. The history, echocardiography and microvolt TWA values based on 24-hour ECG recordings of the patients were evaluated. Analysis of microvolt TWA was considered on the basis of three leads (V5, V1 and AVF).
RESULTS
Compared with the controls, the mean systolic and diastolic blood pressure values and average heart rates were significantly higher in the children with CRF (p = 0.001 and p = 0.026, respectively). Also, the values of left ventricular internal dimensions at end diastole and end-diastolic volume were significantly higher in CRF group (p = 0.01 and p = 0.049, respectively) and couplet ventricular extrasystole was detected in 2 patients with CRF. Consequently, all TWA values in three leads were increased in CRF group than the control group but the only increase in V5 lead was statistically significant (p = 0.028).
CONCLUSIONS
This study has demonstrated that microvolt TWA values increased in pediatric patients with CRF. TWA might be used for early risk assessment in pediatric patients with CRF in the future.
Topics: Adolescent; Arrhythmias, Cardiac; Blood Pressure; Case-Control Studies; Child; Electrocardiography, Ambulatory; Female; Humans; Kidney Failure, Chronic; Male; Prospective Studies
PubMed: 29997001
DOI: 10.1016/j.jelectrocard.2018.04.013