Comparison of electrogram characteristics in persistent atrial fibrillation.

INTRODUCTION: Multiple analysis techniques evaluate electrograms during atrial fibrillation (AF), but none have been established to guide catheter ablation. This study compares electrogram properties recorded from multiple right (RA) and left atrial (LA) sites. METHODS: Multisite LA/RA mapping (281 ± 176/239 ± 166 sites/patient) was performed in 42 patients (30 males, age 63 ± 9 years) undergoing first (n = 32) or redo-AF ablation (n = 10). All electrogram recordings were visually reviewed and artifactual signals were excluded leaving a total of 21 846 for analysis. Electrogram characteristics evaluated were cycle length (CL), amplitude, Shannon's entropy (ShEn), fractionation interval, dominant frequency, organizational index, and cycle length of most recurrent morphology (CLR ) from morphology recurrence plot analysis. RESULTS: Electrogram characteristics were correlated to each other. All pairwise comparisons were significant (p < .001) except for dominant frequency and CLR (p = .59), and amplitude and dominant frequency (p = .38). Only ShEn and fractionation interval demonstrated a strong negative correlation (r = -.94). All other pairwise comparisons were poor to moderately correlated. The relationships are highly conserved among patients, in the RA versus LA, and in those undergoing initial versus redo ablations. Antiarrhythmic drug therapy did not have a significant effect on electrogram characteristics, except minimum ShEn. Electrogram characteristics associated with ablation outcome were shorter minimum CLR , lower minimum ShEn, and longer mimimum CL. There was minimal overlap between the top 10 sites identified by one electrogram characteristic and the top 10 sites identified by the other 10 characteristics. CONCLUSION: Multiple techniques can be employed for electrogram analysis in AF. In this analysis of eight different electrogram characteristics, seven were poorly to moderately correlated and do not identify similar locations. Only some characteristics were predictive of ablation outcome. Further studies to consider electrogram properties, perhaps in combination, for categorizing and/or mapping AF are warranted.

Electrogram morphology recurrence guided catheter ablation for repeat ablation of persistent atrial fibrillation.

BACKGROUND: There are no standard mapping approaches for patients with persistent atrial fibrillation (PeAF), particularly after failed prior catheter ablation (CA). In this study, we assess the feasibility of using Electrogram Morphology Recurrence (EMR) to guide ablation. METHODS: Ten patients with recurrent PeAF after prior CA underwent detailed mapping of both atria during PeAF using the PentaRay (4 mm interelectrode spacing) and 3D mapping with CARTO. At each site, 15 s recordings were made. Custom software identified each electrogram and cross-correlation was used to identify the most recurrent electrogram morphology from which the % recurrence and cycle length of the most repeatable morphology (CLR) was calculated. Sites of shortest CLR and sites within 5 ms of shortest CLR with recurrence ≥ 80% were used to inform CA strategy. RESULTS: A mean of 342.9 ± 131.9 LA and 328.6 ± 91.5 RA sites were recorded per patient. Nine had PV reconnection. Shortest CLR sites guided ablation in 6/10 patients while 1 patient failed to fulfill shortest CLR criteria, and another 3 did not undergo CA guided by shortest CLR due to operator preference. On 12-month follow-up, all 4 patients without shortest CLR guided CA had recurrent PeAF. Of the 6 patients with shortest CLR guided CA, 5 patients did not have recurrent PeAF (p = 0.048), although 1 had paroxysmal AF and 2 had atypical atrial flutter. CONCLUSION: EMR is a feasible, novel technique to guide CA in patients with PeAF. Further evaluation is needed to provide an electrogram-based method for mapping guided targeted ablation of key areas.

Single Fraction and Hypofractionated Radiation Cause Cochlear Damage, Hearing Loss, and Reduced Viability of Merlin-Deficient Schwann Cells.

BACKGROUND: Vestibular schwannomas (VS) are benign intracranial tumors caused by loss of function of the merlin tumor suppressor. We tested three hypotheses related to radiation, hearing loss (HL), and VS cell survival: (1) radiation causes HL by injuring auditory hair cells (AHC), (2) fractionation reduces radiation-induced HL, and (3) single fraction and equivalent appropriately dosed multi-fractions are equally effective at controlling VS growth. We investigated the effects of single fraction and hypofractionated radiation on hearing thresholds in rats, cell death pathways in rat cochleae, and viability of human merlin-deficient Schwann cells (MD-SC). METHODS: Adult rats received cochlear irradiation with single fraction (0 to 18 Gray [Gy]) or hypofractionated radiation. Auditory brainstem response (ABR) testing was performed for 24 weeks. AHC viabilities were determined using immunohistochemistry. Neonatal rat cochleae were harvested after irradiation, and gene- and cell-based assays were conducted. MD-SCs were irradiated, and viability assays and immunofluorescence for DNA damage and cell cycle markers were performed. RESULTS: Radiation caused dose-dependent and progressive HL in rats and AHC losses by promoting expression of apoptosis-associated genes and proteins. When compared to 12 Gy single fraction, hypofractionation caused smaller ABR threshold and pure tone average shifts and was more effective at reducing MD-SC viability. CONCLUSIONS: Investigations into the mechanisms of radiation ototoxicity and VS radiobiology will help determine optimal radiation regimens and identify potential therapies to mitigate radiation-induced HL and improve VS tumor control.

Electrogram Morphology Recurrence for Mapping Persistent Atrial Fibrillation: Initial vs Redo Catheter Ablation.

BACKGROUND: Electrogram (EGM) morphology recurrence (EMR) mapping of persistent atrial fibrillation (AF) quantifies consistency of activation and is expected to be high and rapid near AF drivers. OBJECTIVES: The purpose of this study was to compare EMR in left atria (LA) and right atria (RA) in patients undergoing first vs redo ablation for persistent AF. METHODS: Multisite LA/RA mapping (LA: 281 ± 176 sites/patient; RA: 239 ± 166 sites/patient) before persistent AF ablation was performed in 42 patients (30 males, age 63 ± 9 years) undergoing first (Group 1, n = 32) or redo ablation (Group 2, n = 10). After cross-correlation of each automatically detected EGM with every other EGM per recording, the most recurrent electrogram morphology was identified and its frequency (Rec%) and recurrence cycle length (CLR) were computed. RESULTS: In Groups 1 and 2, minimum CLR was 172.8 ± 26.0 milliseconds (LA: 178.2 ± 37.6 milliseconds, RA: 204.4 ± 34.0 milliseconds, P = 0.0005) and 186.5 ± 28.3 milliseconds (LA: 196.1 ± 38.1 milliseconds vs RA: 199.0 ± 30.2 milliseconds, P = 0.75), with Rec% 94.7% ± 10% and 93.8% ± 9.2%. Group 2 minimum CLR was not different from Group 1 (P = 0.20). Shortest CLR was in the LA in 84% of Group 1 and 50% of Group 2 patients (P = 0.04). Only 1 of 10 patients in Group 2 had the shortest CLR in the pulmonary veins (PVs) compared with 19 of 32 in Group 1 (P = 0.01). Most sites (77.6%) had Rec% <50%. CONCLUSIONS: EMR identified the shortest CLR sites in the PVs in 59% of patients undergoing initial persistent AF ablation, consistent with reported success rates of ∼50% for PV isolation. The majority of sites have low recurrence and may reflect bystander sites not critical for maintaining AF. EMR provides a robust new method for quantifying consistency and rapidity of activation direction at multiple atrial sites.

Mortality in patients with acquired human immunodeficiency virus infection hospitalized in an intensive care unit during the period 2017-2019.

Identify risk factors associated with mortality in HIV patients admitted to an ICU in the city of Bogotá. Retrospective cohort study of patients treated in an ICU during the years 2017-2019. The analysis included descriptive statistics, association tests, and a logistic regression model. A predictive model of mortality at the time of admission to the ICU was developed. 110 HIV patients were identified. Association was found between a Charlson index ≥ 6 and mortality (OR = 2.3, 95% CI 1.0-5.1) and an increase in mortality in the first 21 days of ICU stay (OR = 2.2, 95% CI 1.0-4.9). In the logistic regression analysis, the absence of highly active antiretroviral therapy (HAART) upon admission to the ICU (OR = 2.5 95% CI 1.0-6.1) and the first 21 days of ICU stay (OR = 2.3 95% CI 1.0-5.4) were associated with an increase in mortality. The predictive mortality model established that mortality was higher in patients admitted to the ICU without having previously received HAART than in those who did receive therapy at the time of admission to the ICU. In patients with HIV admitted to the ICU, the absence of HAART will negatively impact mortality during their hospital stay.

Can Electrocochleography Help Preserve Hearing After Cochlear Implantation With Full Electrode Insertion?

OBJECTIVES: To evaluate the utility of intracochlear electrocochleography (ECochG) monitoring during cochlear implant (CI) surgery on postoperative hearing preservation. STUDY DESIGN: Prospective, randomized clinical trial. SETTING: Ten high-volume, tertiary care CI centers. PATIENTS: Adult patients with sensorineural hearing loss meeting the CI criteria who selected an Advanced Bionics CI. METHODS: Patients were randomized to CI surgery either with audible ECochG monitoring available to the surgeon during electrode insertion or without ECochG monitoring. Hearing preservation was determined by comparing preoperative unaided low-frequency (125-, 250-, and 500-Hz) pure-tone average (LF-PTA) to postoperative LF-PTA at CI activation. Pre- and post-CI computed tomography was used to determine electrode scalar location and electrode translocation. RESULTS: Eighty-five adult CI candidates were enrolled. The mean (standard deviation [SD]) unaided preoperative LF-PTA across the sample was 54 (17) dB HL. For the whole sample, hearing preservation was "good" (i.e., LF-PTA change 0-15 dB) in 34.5%, "fair" (i.e., LF-PTA change >15-29 dB) in 22.5%, and "poor" (i.e., LF-PTA change ≥30 dB) in 43%. For patients randomized to ECochG "on," mean (SD) LF-PTA change was 27 (20) dB compared with 27 (23) dB for patients randomized to ECochG "off" ( p = 0.89). Seven percent of patients, all of whom were randomized to ECochG off, showed electrode translocation from the scala tympani into the scala vestibuli. CONCLUSIONS: Although intracochlear ECochG during CI surgery has important prognostic utility, our data did not show significantly better hearing preservation in patients randomized to ECochG "on" compared with ECochG "off."

Speech induced binaural beats: Electrophysiological assessment of binaural interaction.

This paper introduces and evaluates a speech signal manipulation scheme that generates transient speech induced binaural beats (SBBs). These SBBs can only be perceived when different signals are presented dichotically (to both ears). Event-related potentials were recorded in 22 normal-hearing subjects. Dichotic stimulus presentation reliably evoked auditory late responses (ALRs) in all subjects using such manipulated signals. As control measurements, diotic stimulation modalities were presented to confirm that the ALRs were not evoked by the speech signal itself or that the signal manipulation scheme created audible artifacts. Since diotic measurements evoked no ALRs, responses from dichotic stimulation are a pure correlate of binaural interaction. While there are several auditory stimuli (mostly modulated sinusoids or noise) that share this characteristic, none of them are based on running speech. Because SBBs can be added to any arbitrary speech signal, they could easily be combined with psychoacoustic tests, for example speech reception thresholds, adding an objective measure of binaural interaction.

Vibration attenuates spasm-like activity in humans with spinal cord injury.

KEY POINTS: Cutaneous reflexes were tested to examine the neuronal mechanisms contributing to muscle spasms in humans with chronic spinal cord injury (SCI). Specifically, we tested the effect of Achilles and tibialis anterior tendon vibration on the early and late components of the cutaneous reflex and reciprocal Ia inhibition in the soleus and tibialis anterior muscles in humans with chronic SCI. We found that tendon vibration reduced the amplitude of later but not earlier cutaneous reflex in the antagonist but not in the agonist muscle relative to the location of the vibration. In addition, reciprocal Ia inhibition between antagonist ankle muscles increased with tendon vibration and participants with a larger suppression of the later component of the cutaneous reflex had stronger reciprocal Ia inhibition from the antagonistic muscle. Our study is the first to provide evidence that tendon vibration attenuates late cutaneous spasm-like reflex activity, likely via reciprocal inhibitory mechanisms, and may represent a method, when properly targeted, for controlling spasms in humans with SCI. ABSTRACT: The neuronal mechanisms contributing to the generation of involuntary muscle contractions (spasms) in humans with spinal cord injury (SCI) remain poorly understood. To address this question, we examined the effect of Achilles and tibialis anterior tendon vibration at 20, 40, 80 and 120 Hz on the amplitude of the long-polysynaptic (LPR, from reflex onset to 500 ms) and long-lasting (LLR, from 500 ms to reflex offset) cutaneous reflex evoked by medial plantar nerve stimulation in the soleus and tibialis anterior, and reciprocal Ia inhibition between these muscles, in 25 individuals with chronic SCI. We found that Achilles tendon vibration at 40 and 80 Hz, but not other frequencies, reduced the amplitude of the LLR in the tibialis anterior, but not the soleus muscle, without affecting the amplitude of the LPR. Vibratory effects were stronger at 80 than 40 Hz. Similar results were found in the soleus muscle when the tibialis anterior tendon was vibrated. Notably, tendon vibration at 80 Hz increased reciprocal Ia inhibition between antagonistic ankle muscles and vibratory-induced increases in reciprocal Ia inhibition were correlated with decreases in the LLR, suggesting that participants with a larger suppression of later cutaneous reflex activity had stronger reciprocal Ia inhibition from the antagonistic muscle. Our study is the first to provide evidence that tendon vibration suppresses late spasm-like activity in antagonist but not agonist muscles, likely via reciprocal inhibitory mechanisms, in humans with chronic SCI. We argue that targeted vibration of antagonistic tendons might help to control spasms after SCI.

Effect of Bone Marrow-Derived Mesenchymal Stem Cells on Cochlear Function in an Experimental Rat Model.

Mesenchymal stem cell (MSC) therapy is an emerging treatment modality for various human diseases. Although induced pluripotent stem cells have been explored for the restoration of hearing, the potential of MSCs as a therapeutic strategy for various cochlear insults is not precisely known. MSCs possess anti-inflammatory, anti-apoptotic and neuroprotective properties, making them an attractive target for the treatment of inner ear disorders such as hair cell damage in response to inflammation. Most of the previous studies have used immunosuppression or the complex surgical techniques to deliver stem cells into the cochlea. However, no information is available regarding the biocompatibility and safety of MSCs in the inner ear in immunocompetent cochlea. The aim of the present study was to determine the effect of non-surgical administration of rodent bone marrow derived MSCs (BM-MSCs) through transtympanic delivery on the cochlear function and to assess any adverse effects on the auditory system employing a rat model without immunosuppression. We observed that the transtympanic administration of BM-MSCs has no significant effect on the hearing thresholds as determined by auditory brainstem response and distortion product otoacoustic emissions. Histopathological examination revealed no recruitment of inflammatory leukocytes and edema in the cochlea of BM-MSCs administrated rats. The results of this study suggest that transtympanic administration of BM-MSCs is safe and can be explored in providing otoprotection against cochlear insults. Anat Rec, 303:487-493, 2020. © 2019 American Association for Anatomy.

Otoprotection to Implanted Cochlea Exposed to Noise Trauma With Dexamethasone Eluting Electrode.

Cochlear implantation (CI) is now widely used to provide auditory rehabilitation to individuals having severe to profound sensorineural hearing loss (SNHL). However, CI can lead to electrode insertion trauma (EIT) that can cause damage to sensory cells in the inner ear resulting in loss of residual hearing. Even with soft surgical techniques where there is minimal macroscopic damage, we can still observe the generation of molecular events that may initiate programmed cell death via various mechanisms such as oxidative stress, the release of pro-inflammatory cytokines, and activation of the caspase pathway. In addition, individuals with CI may be exposed to noise trauma (NT) due to occupation and leisure activities that may affect their hearing ability. Recently, there has been an increased interest in the auditory community to determine the efficacy of drug-eluting electrodes for the protection of residual hearing. The objective of this study is to determine the effect of NT on implanted cochlea as well as the otoprotective efficacy of dexamethasone eluting electrode to implanted cochlea exposed to NT in a guinea pig model of CI. Animals were divided into five groups: EIT with dexamethasone eluting electrode exposed to NT; EIT exposed to NT; NT only; EIT only and naïve animals (control group). The hearing thresholds were determined by auditory brainstem recordings (ABRs). The cochlea was harvested and analyzed for transcript levels of inflammation, apoptosis and fibrosis genes. We observed that threshold shifts were significantly higher in EIT, NT or EIT + NT groups compared to naive animals at all the tested frequencies. The dexamethasone eluting electrode led to a significant decrease in hearing threshold shifts in implanted animals exposed to NT. Proapoptotic tumor necrosis factor-α [TNF-α, TNF-α receptor 1a (TNFαR1a)] and pro-fibrotic transforming growth factor ß1 (TGFß) genes were more than two-fold up-regulated following EIT and EIT + NT compared to the control group. The use of dexamethasone releasing electrode significantly decreased the transcript levels of pro-apoptotic and pro-fibrotic genes. The dexamethasone releasing electrode has shown promising results for hearing protection in implanted animals exposed to NT. The results of this study suggest that dexamethasone releasing electrode holds great potential in developing effective treatment modalities for NT in the implanted cochlea.

A BCI Gaze Sensing Method Using Low Jitter Code Modulated VEP.

Visual evoked potentials (VEPs) are used in clinical applications in ophthalmology, neurology, and extensively in brain-computer interface (BCI) research. Many BCI implementations utilize steady-state VEP (SSVEP) and/or code modulated VEP (c-VEP) as inputs, in tandem with sophisticated methods to improve information transfer rates (ITR). There is a gap in knowledge regarding the adaptation dynamics and physiological generation mechanisms of the VEP response, and the relation of these factors with BCI performance. A simple, dual pattern display setup was used to evoke VEPs and to test signatures elicited by non-isochronic, non-singular, low jitter stimuli at the rates of 10, 32, 50, and 70 reversals per second (rps). Non-isochronic, low-jitter stimulation elicits quasi-steady-state VEPs (QSS-VEPs) that are utilized for the simultaneous generation of transient VEP and QSS-VEP. QSS-VEP is a special case of c-VEPs, and it is assumed that it shares similar generators of the SSVEPs. Eight subjects were recorded, and the performance of the overall system was analyzed using receiver operating characteristic (ROC) curves, accuracy plots, and ITRs. In summary, QSS-VEPs performed better than transient VEPs (TR-VEP). It was found that in general, 32 rps stimulation had the highest ROC area, accuracy, and ITRs. Moreover, QSS-VEPs were found to lead to higher accuracy by template matching compared to SSVEPs at 32 rps. To investigate the reasons behind this, adaptation dynamics of transient VEPs and QSS-VEPs at all four rates were analyzed and speculated.

Fast acquisition of full-range auditory event-related potentials using an interleaved deconvolution approach.

This work relates to recent advances in the field of auditory event-related potentials (ERP), specifically deconvolution-based ERP acquisition and single-trial processing. An efficient stimulus sequence optimization method for ERP deconvolution is proposed, achieving consistent noise attenuation within a broad designated frequency range. Furthermore, a stimulus presentation paradigm for the fast, interleaved acquisition of auditory brainstem, middle-latency and late responses featuring alternating periods of high-rate deconvolution sequences, and subsequent low-rate stimulation is investigated in 20 normal hearing subjects. Deconvolved sequence responses containing early and middle-latency ERP components are fused with subsequent late responses using a time-frequency resolved weighted averaging method based on cross-trial regularity, yielding a uniform signal-to-noise ratio of the full-range auditory ERP across investigated timescales. Obtained average ERP waveforms exhibit morphologies consistent with both literature values and reference recordings acquired in 15 normal hearing subjects using a prior art approach to full-range auditory ERP acquisition, with all prominent waves being visible in the grand average waveforms. Results suggest the proposed interleaved stimulus presentation and associated ERP processing methodology to be suitable for the fast, reliable extraction of full-range auditory processing correlates in future ERP studies.

Long-term recording of electromyographic activity from multiple muscles to monitor physical activity of participants with or without a neurological disorder.

Various portable monitors have been used to quantify physical activity but most rely on detecting limb movement with a sensor rather than measuring muscle activity. Our first goal was to design and validate a portable system for recording surface electromyographic activity (EMG) from eight muscles over 24 h. The modular system includes: (1) preamplifiers that filter and amplify signals; (2) a preprocessor unit for further filtering and amplification, signal offset and power supply modification; (3) a data-logger for analog-to-digital conversion; a flash memory card for data storage and (4) a rechargeable battery. The equipment samples EMG at 1000 Hz, has a resolution of 2.6 µV and records signals up to 10 mV. The built-in analog filters create a bandwidth appropriate for surface EMG. Our second aim was to test the system biologically by recording EMG from able-bodied and spinal cord injured participants. Modifications were made to electrodes for remote preamplifier placement, and to the battery connection after pilot testing. Thereafter, 31 consecutive 24-h EMG recordings were successful. Both the engineering and biological validation of this system establishes it as a valuable tool for measuring physical activity from different muscles in real-world environments whether individuals have an intact or damaged nervous system.

Spasms after spinal cord injury show low-frequency intermuscular coherence.

Intermuscular coherence allows the investigation of common input to muscle groups. Although beta-band (15-30 Hz) intermuscular coherence is well understood as originating from the cortex, the source of intermuscular coherence at lower frequencies is still unclear. We used a wearable device that recorded electromyographic (EMG) signals during a 24-h period in four lower limb muscles of seven spinal cord injury patients (American Spinal Cord Injury Association impairment scale: A, 6 subjects; B, 1 subject) while they went about their normal daily life activities. We detected natural spasms occurring during these long-lasting recordings and calculated intermuscular coherence between all six possible combinations of muscle pairs. There was significant intermuscular coherence at low frequencies, between 2 and 13 Hz. The most likely source for this was the spinal cord and its peripheral feedback loops, because the spinal lesions in these patients had interrupted connections to supraspinal structures. This is the first report to demonstrate that the spinal cord is capable of producing low-frequency intermuscular coherence with severely reduced or abolished descending drive. NEW & NOTEWORTHY This is the first report to demonstrate that intermuscular coherence between lower limb muscles at low frequencies can be produced by the spinal cord with severely reduced or abolished descending drive.

Caracterización de los pacientes con diagnóstico presuntivo de síndrome coronario agudo sin elevación del segmento ST que asisten a un servicio de urgencias / Profile of patients with non-ST elevation acute coronary syndrome that attend an Emergency Department

Resumen El dolor torácico es uno de los principales motivos de consulta al sistema de urgencias, y este es secundario a condiciones como el síndrome coronario agudo entre otras. Para su diagnóstico se requiere no sólo el resultado de la troponina, sino una evaluación clínica completa en la que se tengan en cuenta factores de riesgo cardiovascular, características del dolor y hallazgos electrocardiográficos. La interpretación inadecuada de las troponinas ultrasensibles lleva a que se someta al paciente a riesgos innecesarios a causa de estudios como el cateterismo cardiaco. Se llevó a cabo un estudio de corte trasversal en un hospital de Bogotá, en el que la causa principal de consulta en el servicio de urgencias fue el dolor torácico, y la primera causa de hospitalización en Cardiología el síndrome coronario agudo. Se recolectaron datos de 411 pacientes a quienes se les realizó arteriografía coronaria, la mayoría hombres con factores de riesgo como hipertensión arterial, tabaquismo y un evento coronario previo. Dentro de los estudios paraclínicos, la fracción de eyección promedio estuvo cercana al 50% y sólo en 201 pacientes se encontraron lesiones epicárdicas significativas.De la muestra analizada, el 13% tenía creatinina mayor de 1,5 mg/dl como causa alterna de elevación del biomarcador y 28% tenía disfunción ventricular izquierda de algún grado. La mayoría de los pacientes en quienes no se documentaron lesiones angiográficamente significativas en el cateterismo cardiaco, la troponina no cumplía criterios de positividad con base en el aumento del 20% respecto al valor inicial si este era positivo o de 50% en caso de que el primer valor fuese negativo. Adicionalmente, del grupo de pacientes con enfermedad coronaria angiográficamente significativa fue más frecuente la combinación de tres o más factores de riesgo cardiovascular en presencia de biomarcador positivo.

Abstract Chest pain is one of the main reasons for consulting the Emergency Department, and it is secondary to conditions, such as acute coronary syndrome. For its diagnosis, it not only requires a Troponin result, but also a full clinical evaluation, in which factors like cardiovascular risk have to be taken into account, as well as characteristics of the pain and the findings on the electrocardiogram. The poor interpretation of the ultrasensitive Troponins leads to the patient being subjected to unnecessary risks due to studies such as cardiac catheterisation. A cross-sectional study was conducted in a hospital in Bogota, in which chest pain was the main reason for consulting the Emergency Department, and acute coronary syndrome the first cause of admission to Cardiology. The study included a total of 411 patients on whom a coronary angiography was performed. The majority were males with risk factors such as arterial hypertension, smokers, and with a previous coronary event. Among the para-clinical studies, the mean ejection fraction was around 50%, and significant epicardial lesions were found in only 201 patients.Of the sample analysed, 13% had a creatinine greater than 1.5 mg/dl as an alternative cause of the elevation of the biomarker, and 28% had some degree of left ventricular function. the majority of patients that did not have significant angiographic lesions in the cardiac catheterisation documented, the Troponin did not meet the criteria for being positive, based on an increase of 20% as regards the initial value if this was positive or 50% in the case where the first value was negative. Furthermore, of the patient group with significant angiographic coronary disease, the combination of three or more cardiovascular risk factors was the most frequent in the presence of a positive biomarker.

Auditory brainstem, middle and late latency responses to short gaps in noise at different presentation rates.

OBJECTIVE: The effects of rate on auditory-evoked potentials (AEP) to short noise gaps (12 ms) recorded at high sampling rates using wide-band filters were investigated. DESIGN: Auditory brainstem (ABR), middle latency (MLR), late latency (LLR) and steady-state (ASSR) responses were simultaneously recorded in adult subjects at four gap rates (0.5, 1, 5 and 40 Hz). Major components (V, Na, Pa, Nb, Pb, N1 and P2) were identified at each rate and analysed for latency/amplitude characteristics. Gap responses at 40 Hz were recovered from Quasi-ASSRs (QASSR) using the CLAD deconvolution method. STUDY SAMPLE: Fourteen right ears of young normal hearing subjects were tested. RESULTS: All major components were present in all subjects at 1 Hz. P1 (P50) appeared as a low-pass filtered component of Pa and Pb waves. At higher rates, N1 and P2 disappeared completely while major ABR-MLR components were identified. Peak latencies were mostly determined by noise onsets slightly delayed by offset responses. CONCLUSIONS: Major AEP components can be recorded to short gaps at 1 Hz using high sampling rates and wide-band filters. At higher rates, only ABR and MLRs can be recorded. Such simultaneous recordings may provide a complete assessment of temporal resolution and processing at different levels of auditory pathways.

Next Generation PERG Method: Expanding the Response Dynamic Range and Capturing Response Adaptation.

PURPOSE: To compare a new method for steady-state pattern electroretinogram (PERGx) with a validated method (PERGLA) in normal controls and in patients with optic neuropathy. METHODS: PERGx and PERGLA were recorded in a mixed population (n = 33, 66 eyes) of younger controls (C1; n = 10, age 38 ± 8.3 years), older controls (C2; n = 11, 57.9 ± 8.09 years), patients with early manifest glaucoma (G; n = 7, 65.7 ±11.6 years), and patients with nonarteritic ischemic optic neuropathy (N; n = 5, mean age 59.4 ± 8.6 years). The PERGx stimulus was a black-white horizontal grating generated on a 14 × 14 cm LED display (1.6 cycles/deg, 15.63 reversals/s, 98% contrast, 800 cd/m2 mean luminance, 25° field). PERGx signal and noise were averaged over 1024 epochs (∼2 minutes) and Fourier analyzed to retrieve amplitude and phase. Partial averages (16 successive samples of 64 epochs each) were also analyzed to quantify progressive changes over recording time (adaptation). RESULTS: PERGLA and PERGx amplitudes and latencies were correlated (Amplitude R2 = 0.59, Latency R2 = 0.39, both P < 0.0001) and were similarly altered in disease. Compared to PERGLA, however, PERGx had shorter (16 ms) latency, higher (1.39×) amplitude, lower (0.37×) noise, and higher (4.2×) signal-to-noise ratio. PERGx displayed marked amplitude adaptation in C1 and C2 groups and no significant adaptation in G and N groups. CONCLUSIONS: The PERGx high signal-to-noise ratio may allow meaningful recording in advanced stages of optic nerve disorders. In addition, it quantifies response adaptation, which may be selectively altered in glaucoma and optic neuropathy. TRANSLATIONAL RELEVANCE: A new PERG method with increased dynamic range allows recording of retinal ganglion cell function in advanced stages of optic nerve disorders. It also quantifies the response decline during the test, an autoregulatory adaptation to metabolic challenge that decreases with age and presence of disease.

Estimating audiometric thresholds using simultaneous acquisition of ASSR and ABR from QASSR in patients with sensorineural hearing loss.

OBJECTIVES: To evaluate the accuracy with which the innovative QASSR method predicts behavioral thresholds in adult patients with sensorineural hearing loss. DESIGN: Subjects were tested at four carrier frequencies (500, 1000, 2000, and 4000 Hz).The resulting QASSR recordings were analyzed for thresholds and magnitude/phase characteristics. Tone-burst ABR was recovered from QASSR signal using CLAD method and analyzed in the time domain. The electrophysiological estimates were compared to hearing thresholds determined behaviorally. STUDY SAMPLE: Sixteen ears of nine volunteer subjects recruited from a clinical population. RESULTS: All mean threshold estimates differed less than 3 dB for QASSR and less than 5 dB for ABR at 1000, 2000 and 4000Hz (carrier or pure-tone test frequencies). The largest differences were observed for both at 500 Hz (5.63 and 11.56 dB respectively).The audiometric configurations of QASSR and ABR estimates followed those of the respective behaviorally determined configurations across ears tested. CONCLUSIONS: QASSR method merges two dissimilar stimulation techniques, transient and steady-state, to create a hybrid stimulation-and-analysis paradigm that seems to improve the overall performance of the electrophysiological threshold estimation. The unique feature of the QASSR technique is the additional information afforded by the transient ABR, recovered from the same recording. The QASSR thus holds promise to be a very useful tool for practical clinical applications.

Electrode array-eluted dexamethasone protects against electrode insertion trauma induced hearing and hair cell losses, damage to neural elements, increases in impedance and fibrosis: A dose response study.

We evaluated the effects of dexamethasone base (DXMb) containing electrode arrays in a guinea pig model of cochlear implantation to determine if eluted DXMb could protect the cochlea against electrode insertion trauma (EIT)-induced: 1) loss of hair cells; 2) disruption of neural elements; 3) increases in hearing thresholds; 4) increased electrical impedance and 5) fibrosis. A guinea pig model of EIT-induced hearing and hair cell losses was used to test silicone electrode arrays that contained either 10%, 1%, 0.1%, or 0% levels of micronized DXMb. These four types of electrode arrays were implanted into the scala tympani via basal turn cochleostomies and left in place for 3 months. Hearing thresholds were determined by ABR and CAP recordings in response to a series of defined pure tone stimuli (i.e. 16-0.5 kHz). Changes in impedance were measured between the implant electrode and a reference electrode. Hair cell counts and neural element integrity were determined by confocal microscopy analyses of stained organ of Corti whole mounts obtained from 90 day post-implantation animals. Fibrosis was measured in Masson trichrome stained cross-sections through the organ of Corti. The results showed that either 10% or 1.0% DXMb eluting electrode arrays protected; hearing thresholds, hair cells, and neural elements against EIT-induced losses and damage. Electrode arrays with 0.1% DXMb only partial protected against EIT-induced hearing loss and damage to the cochlea. Protection of hearing thresholds and organ of Corti sensory elements by electrode-eluted DXMb was still apparent at 3 months post-EIT. All three concentrations of DXMb in the electrode arrays prevented EIT-induced increases in impedance. EIT-initiated fibrosis was significantly reduced within the implanted cochlea of the two DXMb concentrations tested. In conclusion, DXMb eluting electrodes protected the cochlea against long term increases in hearing thresholds, loss of hair cells, damage to neural elements and increases in impedance and fibrosis that result from EIT-initiated damage. The protection achieved by DXMb-eluting electrodes was dose dependent. Establishing a significant level of trauma induced elevation in hearing thresholds was important for the determination of the otoprotective effects of array-eluted DXMb.

Lomb algorithm versus fast Fourier transform in heart rate variability analyses of pain in premature infants.

Heart rate variability analysis is a promising method for measuring pain in premature infants. The Lomb algorithm was adapted and compared with fast Fourier transform (FFT) for the purposes of PSD estimation. Both FFT and the Lomb algorithm had similar low frequency (LF) estimation error rates. However, the Lomb algorithm had a significant smaller error rate than FFT when estimating high frequency (HF). In addition, the ECG signals of two premature infants in the newborn intensive care unit were analyzed while undergoing a routine heel stick, a common painful procedure. The Lomb algorithm performed as expected marking a decrease in both LF and HF power in the presence of pain.