Change In Dominant Frequency Research Articles

High-resolution spatiotemporal changes in dominant frequency and structural organization during persistent atrial fibrillation.

Analyze changes in frequency activity and structural organization that occur over time with persistent atrial fibrillation (AF). Little is known about the frequency characteristics of the epicardium during transition from paroxysmal to persistent AF. Accurate identification of areas of high dominant frequency (DF) is often hampered by limited spatial resolution. Improvements in electrode arrays provide high spatiotemporal resolution, allowing for characterization of the changes that occur during this transition. AF was induced in adult Yorkshire swine by atrial tachypacing. DF mapping was performed using personalized mapping arrays. Histological analysis and late gadolinium enhanced magnetic resonance imaging were performed to determine structural differences in fibrosis. The left atrial epicardium was associated with a significant increase in DF in persistent AF (6.5 ± 0.2 vs. 7.4 ± 0.5 Hz, P = 0.03). The organization index (OI) significantly decreased during persistent AF in both the left atria (0.3 ± 0.03 vs. 0.2 ± 0.03, P = 0.01) and right atria (0.33 ± 0.04 vs. 0.23 ± 0.02, P = 0.02). MRI analysis demonstrated increased ECV values in persistent AF (0.19 vs 0.34, paroxysmal vs persistent, P = 0.05). Tissue sections from the atria showed increase in fibrosis in pigs with persistent AF compared to paroxysmal AF. Staining demonstrated decreased myocardial fiber alignment and loss of anisotropy in persistent AF tissue. Changes in tissue organization and fibrosis are observed in the porcine model of persistent AF. Alterations in frequency activity and organization index can be captured with high resolution using flexible electrode arrays.

Abstract 14839: High-resolution Spatiotemporal Changes in Dominant Frequency and Structural Organization During Persistent Atrial Fibrillation

Introduction: Spatiotemporal differences in atrial activity are thought to contribute to the maintenance of atrial fibrillation (AF). While recent evidence has identified changes in dominant frequency (DF) during the transition from paroxysmal to persistent AF, little is known about the frequency characteristics of the epicardium during this transition. The purpose of this study was to perform high-resolution mapping of the atrial epicardium and to characterize changes in frequency activity and structural organization during the transition from paroxysmal to persistent AF. Hypothesis: In a porcine model of persistent AF, we tested the hypothesis that the epicardium undergoes spatiotemporal changes in atrial activity and structural organization during persistent AF. Methods: Paroxysmal and persistent AF was induced in adult Yorkshire swine by atrial tachypacing. Atrial morphology was segmented from magnetic resonance imaging and high-resolution patient-specific flexible mapping arrays were 3D printed to match the epicardial contours of the atria. Epicardial activation and DF mapping was performed in four paroxysmal and four persistent AF animals using personalized mapping arrays. Histological analysis was performed to determine structural differences between paroxysmal and persistent AF. Results: The left atrial epicardium was associated with a significant increase in DF between paroxysmal and persistent AF (6.5 ± 0.2 vs. 7.4 ± 0.5 Hz, P = 0.03). High-resolution spatiotemporal mapping identified organized clusters of DF during paroxysmal AF which were lost during persistent AF. The development of persistent AF led to structural remodeling with increased atrial epicardial fibrosis. The organization index (OI) significantly decreased during persistent AF in both the left atria (0.3 ± 0.03 vs. 0.2 ± 0.03, P = 0.01) and right atria (0.33 ± 0.04 vs. 0.23 ± 0.02, P = 0.02). Conclusions: In the porcine model of persistent AF, the epicardium undergoes structural remodeling with increased epicardial fibrosis, reflected by changes in atrial organization index and dominant frequency.

FREQUENCY ESTIMATION FOR ATRIAL FIBRILLATION FROM HUMAN STUDIES

Atrial Fibrillation (AF) is the most common disorder of the heart rhythms. There are about 2.3 million people in United States and 4.5 million people in the European Union with AF [1]. It is also one of the factors that may contribute to mortality and morbidity. Researchers who apply spectral techniques show that certain areas of the atria can have higher activation frequencies than other areas. Frequency analysis is used to measure changes in Dominant Frequency (DF). We access the electrical propagation inside the atria by spectrogram plotting and examining the effect of high frequency stimulation on human.

Experimental Analysis of the Dimorphic Function of the Biphasic Call ofEleutherodactylus johnstonei(Anura: Eleutherodactylidae)

Abstract We investigated the communicative function of the two notes of the advertisement call of Johnstone's whistling frog, Eleutherodactylus johnstonei, by broadcasting standard two-note calls and edited one-note calls to males in the field and to females in two-choice trials. We tested the hypothesis that each note has distinct signaling function for each sex such as has been demonstrated for the congener E. coqui. We analyzed phonotaxis in females and changes in duration and dominant frequency of each note and also in call period in the acoustic responses of males. Females were equally likely to approach a source broadcasting a standard call or the second note alone, but rejected sources broadcasting the first note alone. This indicated that the second note mediates female attraction, much as in the congener E. coqui. Male responses indicated that either note is as effective as the standard call in eliciting a change in the dominant frequency of both notes, although the modification is small quantita...

Left atrial coronary perfusion territories in isolated sheep hearts: Implications for atrial fibrillation maintenance

The role of coronary perfusion in the maintenance of atrial fibrillation (AF) electrical sources that anchor to the posterior (wall of the) left atrium (PLA) has been incompletely investigated. We hypothesized that the PLA-pulmonary vein region is perfused by branches originating from both the right and left coronary arteries. The purpose of this study was to evaluate whether branches originating from the right and left coronary arteries could serve as conduits to chemically ablate restricted PLA regions. In Langendorff-perfused sheep hearts, the right anterior and left anterior atrial arteries (RAAA and LAAA) and the branches of the left circumflex artery (LCX) were identified as main coronary artery branches perfusing the atria. During sustained AF, 20-mL boluses of cold Tyrode's solution (4°C) was injected into each artery to determine changes in dominant frequency. The injection that yielded the largest dominant frequency decrease indicated the coronary branch to be subsequently perfused with ethanol. Ethanol was selectively injected into the LAAA (n = 4), LCX (n = 4), or RAAA (n = 1). Six of nine AF cases rapidly terminated upon ethanol perfusion. In those hearts and in eight additional preparations (n = 17), Congo red and Evans blue was subsequently perfused into the remaining atrial branches. The perfusion territories were classified as triple-vessel PLA perfusion (n = 4), LAAA-dominant PLA perfusion (n = 5), balanced double-vessel PLA perfusion (n = 5), and LCX or RAAA dominant (n = 3). PLA coronary perfusion relies on a variable contribution of right and left coronary branches. Regional irrigation of ethanol in well-delineated PLA perfusion territories enabled ablation of high-frequency sites during AF.

Effects of Two Different Catheter Ablation Techniques on Spectral Characteristics of Atrial Fibrillation

The aim of this study was to determine the effects of circumferential pulmonary vein ablation (CPVA) and electrogram-guided ablation (EGA) on the spectral characteristics of atrial fibrillation (AF) and the relationship between changes in dominant frequency (DF) and clinical outcome. Circumferential pulmonary vein ablation and EGA have been used to eliminate AF. Spectral analysis may identify high-frequency sources. In 84 consecutive patients, CPVA (n = 42) or EGA (n = 42) was performed for paroxysmal (n = 49) or persistent (n = 35) AF. During EGA, complex electrograms were targeted. Lead V1 and electrograms from the left atrium and coronary sinus were analyzed to determine the DF of AF before and after ablation. The left atrial DF was higher in persistent (5.83 +/- 0.86 Hz) than paroxysmal AF (5.33 +/- 0.76 Hz, p = 0.03). There was a frequency gradient from the left atrium to the coronary sinus (p = 0.02). Circumferential pulmonary vein ablation and EGA resulted in a similar decrease in DF (18 +/- 17% vs. 17 +/- 15%, p = 0.8). During a mean follow-up of 9 +/- 6 months, the change in DF after CPVA was similar among patients with and without recurrent AF. An acute decrease in DF after EGA was associated with freedom from recurrent AF only in patients with persistent AF (19 +/- 14% vs. 3 +/- 6%, p = 0.02). Both CPVA and EGA decrease the DF of AF, consistent with elimination of high-frequency sources. Whereas the efficacy of EGA is associated with a decrease in DF in patients with persistent AF, the efficacy of CPVA is independent of changes in DF. This suggests that CPVA and EGA eliminate different mechanisms in the genesis of persistent AF.

P5-51: Changes in dominant frequency of right atrial and coronary sinus electrograms during progressive ablation to identify patients with potential fibrillation drivers outside the left atrium

P5-51: Changes in dominant frequency of right atrial and coronary sinus electrograms during progressive ablation to identify patients with potential fibrillation drivers outside the left atrium

Temporal call changes and prior experience affect graded signalling in the cricket frog

We investigated how male cricket frogsAcris crepitans, alter their advertisement calls in response to broadcasts of synthetic calls that were either ‘attractive’ or ‘aggressive’. The stimulus calls differed in temporal but not spectral characteristics. Male cricket frogs produced a more aggressive call when presented with the aggressive stimulus, indicating that they perceived the temporal differences between the two call categories. The direction and degree of temporal and spectral changes depended on the relative dominant frequency of the resident and opponent. If the resident’s dominant frequency was initially higher than the stimulus frequency, the pattern of change in dominant frequency mirrored that seen for the temporal call characters. In contrast, if the resident’s initial dominant frequency was below that of the stimulus, then the temporal and spectral changes were in opposite directions. Furthermore, stimulus order influenced whether males responded differently to playbacks of aggressive and attractive calls; males that received the aggressive call first produced more aggressive calls during the aggressive stimulus, while males that received the attractive call first produced similar calls in response to the two stimuli. This suggests that experience with different types of signals influences the subsequent calling behaviour of male cricket frogs.

Wavelet analysis of rainfall–runoff variability isolating climatic from anthropogenic patterns

Continuous wavelet transforms (CWTs) are used to identify the temporal variability of rainfall and runoff and their relationship. The wavelet analysis is applied to rainfall and runoff records from Peak Hill and Neurie Plains, in the upper Bogan River catchment in central western New South Wales, Australia, as well as to the large-scale circulation index SOI. A method utilising wavelet analysis is being developed to identify and isolate the `natural' climatic components of the hydrological record, by using SOI correlations, as well as to distinguish the influence of other non-stationary trends, such as anthropogenic land use changes, on runoff records over time. Results using the Morlet wavelet show that the variability of both rainfall and runoff as well as their relationship has changed over time. A wavelet spectrum analysis shows a change in dominant frequency since the 1950s. Climate induced catchment response is at short time scales (27–32 months over the time period 1911–1996). The relationship between the SOI and rainfall is stronger from the 1950s onwards, with a dominant frequency of SOI at 27 months. The non-stationary, multiscale time series analysis could be important in floodplain management and development decisions, for the insurance industry, and in engineering, by identifying past changes, by detecting streamflow response to climate changes, and by aiding in future flood and drought predictability.

Electrogastrographic Study of the Effect of Transcatheter Arterial Chemoembolization on Gastric Myoelectric Activity

Background: Transcatheter arterial chemoembolization (TACE) of the hepatic artery is frequently used in the treatment of inoperable hepatocellular carcinoma (HCC). TACE causes not only effective tumor tissue necrosis in patients with hepatoma but also adverse effects on extrahepatic abdominal organs. There are no published reports on the effect of TACE on the gastric myoelectric activity. In this study, using cutaneous electrogastrography (EGG), we evaluated the effect of TACE on gastric myoelectric activity in patients with HCC. Methods: A total of 27 patients (24 men and 3 women, aged 22 to 78 years) with hepatoma, admitted for TACE, were included in this study. Furthermore, 28 patients (24 men and 4 women, aged 26 to 75 years), admitted for diagnostic angiography of the liver, served as the control group. Cutaneous EGG was performed before and after TACE or angiography. Results: In the TACE group there were significant changes in dominant frequency (DF) and percentages of DF in the defined normal range, bradygastric range, and tachygastric range on post-meal EGG. On fasting EGG, only the dominant frequency and percentages of DF in the bradygastric range changed significantly. However, there was no correlation between the occurrence of nausea/vomiting and the degree of change in the EGG variables, during both fasting and postprandial states. In the control group there were no significant differences in EGG variables before and after angiography. Conclusions: TACE can affect gastric myoelectric activity in HCC patients. Nevertheless, the relationship between changes in myoelectric activity and the occurrence of gastrointestinal symptoms needs further investigation.

Effect of Vehicle Speed on Sound Frequency Spectra

During analysis conducted on data collected by the University of Central Florida for the Florida Department of Transportation (FDOT), which was doing research to develop reference energy mean emission levels for high-speed traffic, other interesting data trends became apparent. One such trend was the relationship of vehicle speed and sound emission spectra. The data base contained real-time one-third octave band data and vehicle characteristics (e.g., speed) and permitted a detailed review of sound emission spectra with respect to vehicle speed. The purpose of this research was to attempt to develop a mathematical relationship between increasing vehicle speed and sound emission spectra. Based on the results of this research several important conclusions were drawn: (a) a trend in the change in sound frequency spectra with respect to vehicle speed may exist for all vehicle types defined in STAMINA 2.0; (b) the change in dominant frequency followed no apparent trend with respect to vehicle speed; (c) the data base used for this research was too small for accurate mathematical modeling of the change in sound frequency versus vehicle speed; and (d) the sound attenuation provided by noise barriers may be underestimated using the current method of estimating barrier attenuation based on an effective frequency of 500 Hz regardless of vehicle speed.

Effect of Vehicle Speed on Sound Frequency Spectra

During analysis conducted on data collected by the University of Central Florida for the Florida Department of Transportation (FDOT), which was doing research to develop reference energy mean emission levels for high-speed traffic, other interesting data trends became apparent. One such trend was the relationship of vehicle speed and sound emission spectra. The data base contained real-time one-third octave band data and vehicle characteristics (e.g., speed) and permitted a detailed review of sound emission spectra with respect to vehicle speed. The purpose of this research was to attempt to develop a mathematical relationship between increasing vehicle speed and sound emission spectra. Based on the results of this research several important conclusions were drawn: (a) a trend in the change in sound frequency spectra with respect to vehicle speed may exist for all vehicle types defined in STAMINA 2.0; (b) the change in dominant frequency followed no apparent trend with respect to vehicle speed; (c) the data base used for this research was too small for accurate mathematical modeling of the change in sound frequency versus vehicle speed; and (d) the sound attenuation provided by noise barriers may be underestimated using the current method of estimating barrier attenuation based on an effective frequency of 500 Hz regardless of vehicle speed.

The role of articulation in the production of rhesus monkey, Macaca mulatta, vocalizations

Abstract. Many non-human primates have large and acoustically diverse vocal repertoires. However, our understanding of the phonatory mechanisms underlying such acoustic variation is poor. Representative exemplars of some of the articulatory gestures used by free-ranging rhesus monkeys while uttering a range of vocalizations are provided. Results reveal that different call types appear to be associated with characteristic lip configurations and mandibular positions. Quantitative analyses of the 'coo' vocalization indicate that changes in the position of the mandible are reliably associated with changes in dominant frequency (i.e. resonance frequency), but not with changes in fundamental frequency. This finding suggests that rhesus monkeys can modify the spectral properties of the signal, independent of the glottal source (i.e. fundamental frequency). Such articulatory manoeuvres contribute to the animal's potential acoustic space, thereby potentially increasing the array of meaningful vocalizations within the repertoire.

Call patterns and basilar papilla tuning in cricket frogs. I. Differences among populations and between sexes.

Male cricket frogs (Acris crepitans) produce a broad-band, high frequency advertisement call with a single spectral peak (the dominant frequency). We measured the dominant frequencies of male calls from six populations in central Texas and one from Indiana and compared them to the tuning of basilar papilla afferents in males and females. Averaging over all populations, mean call dominant frequency was 3.69 kHz, mean male basilar papilla tuning was 3.63 kHz, and mean female basilar papilla tuning was 3.17 kHz. Among populations, mean dominant frequency varied from 3.56 kHz to 3.82 kHz. Dominant frequencies were slightly higher in the more eastern Texas populations occupying pine forest habitats than in the more western populations occupying open grassland habitats. Changes in dominant frequency in a population coincided with changes in tuning of both male and female basilar papillae. Furthermore, within populations females were tuned on average lower than males and lower than the mean dominant frequency of calls in their own population. We suggest that the coincident changes in calls and basilar papilla tuning plus the sexual difference in tuning indicate that female mate choice would be directed toward males from her home population with low frequency calls or toward males from foreign populations with average calls lower in frequency than those in her home population. This in turn suggests that any gene flow between populations would be biased from east to west and from forest to open habitats.

The electroencephalogram in kwashiorkor

1. 1. Serial EEGs were recorded from 33 young African kwashiorkor patients, 10 of whom were anaemic. Serial EEGs were also obtained from 11 control children and single recordings from a further 14 kwashiorkor patients and 27 controls. 2. 2. Abnormal (focal) records were found in 36 per cent of the kwashiorkor patients, all except one in the form of disturbances in the temporal region. Most of the abnormalities were seen in sleep records. 3. 3. During recovery there was usually a marked increase in dominant EEG frequency and in response to photic stimulation. The dominant frequencies of the kwashiorkor children were mostly below the range for normal American children of the same age, even after clinical recovery. No comparable serial EEG changes occurred in the controls, and dominant frequencies were similar to those of normal American children. 4. 4. The changes in dominant frequency during recovery might reflect an impeding effect of kwashiorkor on the development of brain rhythms in childhood. This effect may persist into adulthood. 5. 5. Neither anaemia nor BMR appear to be responsible for the EEG changes, whereas psychological factors may be of significance.