Call description and extended range of Phrynobatrachus mayokoensis in Gabon

Changes in the Spectral Characteristics of Ventricular Fibrillation in Lesions Produced by Radiofrequency Ablation. An Experimental Study

This study analyses the frequency content of vibrations from blasting in the near field using a vibration prediction model called full-field solution (FFS). For that purpose, the frequency content of recorded signals and synthetic waveforms obtained through the FFS using dominant and mean frequencies have been compared and correlated with the geometrical distance to the blastholes. The study shows that the model overestimates the dominant and mean frequencies in the entire frequency domain, which may require tailoring the source function to a lower frequency content. However, it attenuates the frequency content as distance increases. Additionally, the study shows that the mean frequencies may be used as a better estimator of the frequency content than the dominant frequencies.

Periods of reentrant activation and effective refractory periods are correlated with dominant frequency or reciprocal of cycle periods during ventricular fibrillation (VF). In the present study, we used an analysis technique based on Wigner transforms to quantify time-varying dominant frequencies in electrocardiograms (ECGs) during VF. We estimated dominant frequencies within orthogonal ECGs recorded in 10 dogs during trials of 10 s of VF and in 9 dogs during trials of 30 s of VF. In four additional dogs, we compared dominant frequencies during 10 s of VF before and after administration of amiodarone. Our results showed the following. 1) There was substantial frequency variation or modulation within the ECGs during 10 and 30 s of VF, the average variation being +/-15% from the mean frequency. Amiodarone decreased mean frequencies (P < 0.05) as expected; however, amiodarone also decreased the variation in frequencies (P < 0.05). 2) During 30 s of VF, the dominant frequencies increased continuously from 7.3 to 8.1 Hz (P < 0.05). The increase in frequency was almost linear with a rate of 0.022 Hz/s (r(2) = 0.93, P < 0.0005). 3) Modulation of frequencies during the first and the last one-half of 30 s of VF was not different. Average (in time) mean frequencies and modulation of frequencies were similar in all three ECGs. 4) Although the averages were similar, during any VF episode, dominant frequencies in ECGs recorded from different locations on the body surface were similar to each other at some times and markedly different from each other at other times. We conclude that during VF, 1) frequencies in ECGs vary considerably and continuously, and amiodarone decreases this variation; 2) mean frequencies increase linearly during first 30 s; 3) the variability in frequency does not change during 30 s; and 4) at any given time, the frequencies within spatially different body surface ECGs can be either similar or markedly different.

Mango cultivars, i.e. Neelam, Alphonso, Banganapalli, Totapuri, and Mallige were subjected to acoustic resonance spectroscopy at unripe, semi-ripe, and ripe stages, as well as in case of ripe bruised fruits. The Neelam variety of mango was screened for internal infestation by means of acoustic spectroscopy. Acoustic data on dominant and first frequencies, damping ratio, and firmness indices were obtained and correlated with mechanical penetration tests as well as a/b values of the tristimulus color profile. The correlations between mechanical tests and acoustic parameters varied from 0.81 to 0.933. However, damping ratio and dominant frequency along with firmness index showed a better correlation with penetration test vis-à-vis first frequencies. The correlations between acoustic parameters and a/b tristimulus color values showed lesser extent and significance of correlations ranging from 0.416 to 0.667. The correlations were found to be positive or negative depending on the specific acoustic parameters. However, in the case of internally infested Neelam, the drop in the first frequency was found to be a significant acoustic indicator. Nondestructive quality monitoring by acoustic spectroscopy was found as such to be consistent as far as the tissue softening and bruising are concerned.

Within the genus Cacosternum, the species C. capense and C. namaquense form a clade defined by their robust morphology, large size, and distinct dorsolateral glands. In this study, we describe a third member of the group endemic to the Cederberg region of South Africa. Specimens from this area have historically been assigned to C. karooicum, but here we show that this population is genetically unrelated. Using a combination of molecular, morphological, and acoustic data, we provide evidence to show that the Cederberg population of C. karooicum represents an undescribed species within the C. capense group. The new species can be diagnosed from its closest phylogenetic relatives, C. capense and C. namaquense, by the absence of a dark streak running downwards from the pupil into the iris, the presence of large rictal glands that form an uninterrupted arc with the angle of the jaw, heart-shaped palmar tubercles, and an advertisement call with a dominant frequency below 2 kHz. We further discuss their natural history, distribution, and conservation.

Effect of pilsicainide on dominant frequency in the right and left atria and pulmonary veins during atrial fibrillation: Association with its atrial fibrillation terminating effect

Relationship between cracked-zone radius and dominant frequency of vibration in tunnel blasting

Introduction: Stable high frequency sources and rotors have been described to drive episodes of atrial fibrillation (AF) but the mechanism for their stability is unknown. We used a chronic animal model of AF to test the hypothesis that fibrosis anchors sites of high frequency activation during AF, which may drive the arrhythmia.. Methods: Endocardial electrograms were measured with a Constellation catheter (Boston Scientific) placed in the left atrium (LA) of chronic AF dogs (n=6) (AF &gt; 12 months). An EnSite (St. Jude) geometric shell was then fused with a LA wall created by segmenting a high resolution T1 Mapping MRI. Regions with the lowest 10% T1 in the LA wall, used as a surrogate measure of fibrosis, were included on the LA wall segmentation. Fibrosis densities were calculated from histology and correlated with T1 Mapping MRI. Electrograms recorded during AF were processed to determine the dominant frequency (DFs) at each recording site. A probability map with the highest 10% DF value for each minute of AF at each of the sites was created to determine the stability of the DF during the 30 min AF episode. Results: Each AF animal had at least one site of high DF which was stable for at least 22.5 (75%) of a 30-minute AF episode and 82% of the high DF sites stabilized within 2 mm of a region of fibrosis (chi square test, p &lt; 0.05). The mean DF was 8.5±1.2 Hz and the highest DF sites showed an average DF of 10.3±1.1 Hz. The region of T1 Mapping MRI detected fibrosis of the LA wall had an average value of 283±32 ms whereas the rest of the LA had an average value of 463±79 ms. Histology confirmed that that T1 Mapping MRI detected fibrosis had more fibrosis than other LA regions. (25±1% vs. 13±2%). Conclusions: Fibrosis developed during chronic AF may provide a substrate that anchors sites of high DF. Cardiac T1 Mapping MRI provides a means to determine such fibrotic sites noninvasively. Ablating these sites may reduce the stability of these high frequency sources and eliminate the drivers of persistent AF.

Organized patterns of excitation during persistent atrial fibrillation in humans relate to tissue structure and activation rate

Background: Although the dominant frequency (DF) may localize the reentrant drivers of atrial fibrillation (AF), its meandering nature makes it difficult to localize as an extra-pulmonary vein (extra-PV) target. Hypothesis: We explored and quantified the spatiotemporal stability of DF by sophisticated digital-twin maps and the association with the rhythm outcome of clinical AF catheter ablation (AFCA). Methods: We retrospectively examined the DF sites in the digital twin integrated by high-density electroanatomical maps (EAM) of 170 patients previously included in the CUVIA-AF2 trial (male 70.6%, 59.2±11.3 years old, 100% persistent AF). We monitored 34 seconds of virtual AF and analyzed DF sites in 10 different left atrial (LA) regions at 3 consecutive periods (6 seconds each after 16 seconds of induction and blanking periods). The spatiotemporal stability index (STSI) was calculated to quantify mean DF's spatial and temporal variability. During protocol-based rhythm follow-up, we assessed the atrial arrhythmia recurrence rate by dividing patients into two groups based on STSI 0.75. Results: During the simulation, 108 out of 170 (63.5%) patients recorded the mean DF in all consecutive periods. There were 26 (24.1%) patients in the stable DF group (STSI ≥0.75, Stable group) and 82 (75.9%) patients in the unstable DF group (STSI &lt;0.75, Unstable group). Although the proportion of patients with hypertension (73.1 vs. 47.6%, p=0.041) was higher and left ventricular end-diastole diameter (51.3±3.9 vs. 49.0±4.4 mm, p=0.020) was larger in the stable DF group than in the unstable DF group, other parameters, including LA size, LA voltage, or AF ablation targets, did not differ between two groups. During the median 19 [15-22] months follow-up, the atrial arrhythmia recurrence rate of the Stable group is higher than that of the Unstable group (log-rank p=0.031, HR = 2.06, CI [1.06-4.01]) Conclusions: We found that the temporally stable DF in EAM-integrated virtual AF, the potential extra-PV AF drivers, is a surrogate marker of the adverse rhythm outcome of AFCA. A prospective clinical trial targeting the spatiotemporally stable DF will be warranted.

Spatiotemporal stability of digital twin-guided atrial fibrillation dominant frequency sites and the clinical outcome of catheter ablation

The ability to acquire a dominant frequency (DF) map during atrial fibrillation (AF) instantaneously using noncontact mapping has significant advantages over the current sequential contact mapping approach; however, the relationship between DFs determined from contact bipolar and noncontact unipolar recordings is unknown. We sought to determine the difference between DFs determined using contact bipolar, contact unipolar, noncontact unipolar, and noncontact pseudobipolar recordings. Sustained AF was induced in 5 canines with 10 weeks of atrial tachy-pacing at 440 ppm. A noncontact multielectrode array was positioned in the left atrium (LA). Two simultaneous contact signals (unipolar and bipolar) and 3 noncontact signals (unipolar, pseudobipolar, and pseudobipolar Laplacian) were recorded from multiple LA sites. Fourier analysis was performed, and the DFs of contact and noncontact signals were compared. Recordings were obtained from 389 LA locations in 5 canines. The correlation was best between contact bipolar and noncontact QRS-subtracted unipolar signals (r = 0.58, P < 0.001), and weaker between contact bipolar and noncontact best-fit pseudobipolar (r = 0.50, P < 0.01) and noncontact Laplacian bipolar (r = 0.49, P < 0.01). There was no significant difference in the mean DFs between contact bipolar and noncontact unipolar signals; however, there was a significant difference in the DFs comparing contact bipolar to noncontact pseudobipolar signals (11.6 +/- 1.8 vs 11.2 +/- 2.5 Hz; P = 0.004) and a small nonsignificant difference comparing contact bipolar DF and noncontact pseudobipolar Laplacian DF (11.4 +/- 1.8 vs 11.1 +/- 1.6 Hz; P = NS). We found that estimation of DFs using noncontact mapping is feasible and that QRS-subtracted noncontact unipolar signals perform better than noncontact pseudobipolar signals at estimating contact bipolar DFs. This has important implications for developing algorithms for noncontact frequency mapping of AF.

AimVentricular fibrillation (VF) is normally a sustained condition, and electrical shock is required to end it. In the laboratory, we found that the defibrillation thresholds of VF lasting for the...

Sites of high DF are potential targets for AF ablation, but it is unknown if addition of DF ablation can improve procedural outcome. We sought to (1) examine the relationship between DF sites and complex fractionated electrograms (CFE) and (2) prospectively assess the long-term outcome of adding DF ablation to pulmonary vein antral isolation (PVAI) for persistent AF. First, 20 patients with persistent AF who underwent previous CFE-guided ablation and who had AF terminate during ablation were studied retrospectively (group I). Bipolar, 8-second electrograms were collected by a circular catheter (288 ± 86 points/map). The EnSite NavX system allows for automated display of both CFE and DF maps. Electrograms with cycle length <120 ms were considered CFE and were compared to DF sites > 8 Hz (direct inverse relationship). Sites of AF termination were related to CFE and DF sites. Based on these observations, 30 different patients (group II) with persistent AF prospectively underwent DF-guided ablation plus PVAI. They were followed every 3 months for 1 year (visit, Holter, ECG). These patients were compared to case-matched controls undergoing PVAI alone (group III). In group I, there was a significant, inverse correlation between DF and CFE values at each point (r =-0.24, P < 0.001). DF surface area was less than CFE area (27 ± 5 cm(2) vs 34 ± 4 cm(2) , P = 0.03). CFE sites overlapped 48 ± 27% with the DF surface area. Nonoverlapping CFE sites were contiguous to DF sites. AF termination occurred where DF and CFE overlapped, and at these sites, DF was always greater than the mean DF for the map. In group II, all DF sites above the mean value were prospectively ablated during AF. AF termination was noted in only 2/30 (7%) patients. After DF ablation, PVAI was performed and termination increased to 4/30 patients (14%). At 1 year, freedom from atrial arrhythmia > 30 seconds occurred in 57% of DF+PVAI compared to 60% in patients receiving PVAI alone (P = 0.18). DF and CFE regions overlap only about 50%. AF termination retrospectively occurred on overlapping CFE/DF sites where DF was above the mean. However, prospective ablation of DF sites plus PVAI resulted in low AF termination rates, and did not improve 1 year success over PVAI alone.

External morphology and calling song characteristics in Tibicen plebejus (Hemiptera: Cicadidae)