Atrial slow conduction develops and dynamically expands during premature stimulation in an animal model of persistent atrial fibrillation

Slow conduction areas and conduction block in the atria are considered pro-arrhythmic conditions. Studies examining the size and distribution of slow conduction regions in the context of persistent atrial fibrillation (AF) may help to develop improved therapeutic strategies for patients with AF. In this work, we studied the differences of size and number in slow conduction areas between control and persistent AF goats and the influence of propagation direction on the development of these pathological conduction areas. Epicardial atrial electrical activations from the left atrial roof were optically mapped with physiological pacing cycle lengths and for the shortest captured cycle lengths. The recordings were converted to local activation times and conduction velocity measures. Regions with slow conduction velocity (less than 0 . 2 m s) were identified. The size of the connected regions and the number of non-connected regions were counted for propagation from different orthogonal directions. We found that regions of slow conduction significantly increases in our 15 persistent AF goat recordings in response to premature stimulation (24.4±4.3% increase to 36.6±4.4%, p < 0.001). This increase is driven by an increase of size from (3.70±0.89[mm2] to 6.36±0.91[mm2], p = 0.014) for already existing regions and not by generation of new slow conduction regions (11.6±1.8 vs. 13±1.9, p = 0.242). In 12 control goat recordings, no increase from baseline pacing to premature pacing was found. Similarly, size of the slow conduction areas and the count did not change significantly in control animals.

Rotational activity presence and its impact in persistent atrial fibrillation follow-up

Introduction Treatment of atrial fibrillation (AF) remains sub-optimal, with low success in pulmonary vein isolation (PVI) ablation procedures in long-standing-persistent AF patients. The maintenance mechanisms of AF are still under debate. Rotational activity (RA) events, also known as rotors, may play a role in perpetuating AF. The characterisation of these drivers during electroanatomical (EA) guided ablation procedures in relationship with follow-up and recurrence ratios in AF patients is necessary to design new ablation strategies to improve the AF treatment success. Purpose We report an AF patient cohort of endocardial mapping and PVI ablation procedures with additional RA events detected during the EA study. We aim to study the presence and distribution of RA in AF patients and its impact on AF recurrence when only PVI ablation is performed. Methods 75 persistent consecutive AF patients (age 60.7±9.8, 74.7% men) underwent EA mapping and RA detection with an automatic algorithm. The presence of RA was annotated on the EA map based on the unipolar electrograms (EGMs) registered with a 20-pole catheter. RA presence was analysed at different left atrial locations (37.2±14.8 sites per patient). AF recurrence was evaluated in follow-up after treatment. Results At follow-up (9±5 months), 50% of the patients presented AF recurrence. Patients with RA had more dilated atria in terms of volumes (p=0.002) and areas (p=0.001). Patients with RA exhibited higher mean voltage EGMs 0.6±0.3 mV vs 0.5±0.2 mV (p=0.036), with shorter cycle lengths 169.1±26.0 ms vs. 188.4±44.2 ms (p=0.044). Finally, patients with RA presented more AF recurrence rates than patients with no RA events (p=0.007). No significant differences were found in terms of comorbidities, e.g., heart failure, hypertension, COPD, stroke, SHD, or diabetes mellitus. Conclusions The results show that patients with more RA events and those with RA outside the PVI ablated regions presented higher AF recurrence episodes than those with no RA or events inside the areas affected by radio-frequency ablation. The study suggests that further ablation treatment of the areas harboring RA might be necessary to reduce the recurrence ratio in AF patients. FUNDunding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Instituto de Salud Carlos III; Sociedad Española de Cardiología

Investigation of Shape-from-Focus Precision by Texture Frequency Analysis

This paper reports the precision of shape-from-focus (SFF) imaging according to the texture frequencies and window sizes of a focus measure. SFF is one of various depth measurement techniques for optical imaging, such as microscopy and endoscopy. SFF measures the depth of an object according to focus measure, which is generally computed with a fixed window. The window size affects the performance of SFF and should be adjusted for the texture of an object. In this study, we investigated the precision difference of SFF in texture frequencies and by window size. Two experiments were performed: precision validation in texture frequencies with a fixed window size, and precision validation in various window sizes related to pixel-cycle lengths. The first experimental results showed that a smaller window size could not provide a correct focus measure, and the second results showed that a window size that is approximately equal to a pixel-cycle length of the texture could provide better precision. These findings could potentially contribute to determining the appropriate window size of focus measure operation in shape-from-focus reconstruction.

Impact of Turning Lane Storage Length and Turning Proportions on Throughput at Oversaturated Signalized Intersections

During oversaturated conditions, common objectives of signal timing are to maximize vehicle throughput and manage queues. A common response to increases in vehicle volumes is to increase the cycle length. Because the clearance intervals are displayed less frequently with longer cycle lengths and fewer cycles, more of the total time is used for green indications, which implies that the signal timing is more efficient. However, previous studies have shown that throughput reaches a peak at a moderate cycle length and extending the cycle length beyond this actually decreases the total throughput. Part of the reason for this is that spillback caused by the turning traffic may cause starvation of the through lanes resulting in a reduction of the saturation flow rate within each lane. Gaps created by the turning traffic after a lane change may also reduce the saturation flow rate. There is a relationship between the proportions of turning traffic, the storage length of turning lanes, and the total throughput that can be achieved on an approach for a given cycle length and green time. This study seeks to explore this relationship to yield better signal timing strategies for oversaturated operations. A microsimulation model of an oversaturated left-turn movement with varying storage lengths and turning proportions is used to determine these relationships and establish a mathematical model of throughput as a function of the duration of green, storage length, and turning proportion. The model outcomes are compared against real-world data.

The 35-Day Cycle of Hercules X-1 in Multiple Energy Bands from MAXI and Swift/BAT Monitoring

Hercules X-1 (Her X-1) has been monitored by MAXI and by Swift/BAT for over a decade. Those observations are analyzed to measure the shape and energy dependence of the long-term average of the 35-day cycle of Her X-1. The cross-correlation (CC) method is used to determine peak times and cycle lengths. Swift/BAT data produces better 35-day times because of the gaps in the MAXI data. Using Swift/BAT-derived times, average 35-day cycle light-curves are created for multiple energy bands: MAXI’s 2–20 keV, 2–4 keV, 4–10 keV and 10–20 keV bands and Swift/BAT’s 15–50 keV band. The durations of the different states of the 35-day cycle are measured better than previously. We find clear changes in X-ray softness ratio with 35-day phase, and detect persistent features in the 35-day cycle. These include column density changes during turn-on of Main High and of Short High states, and persistent absorption dips during the bright part of Main High and of Short High states.

Improving the Capacity and Level of Service at the Sixth Circle in Jordan by Using Traffic Signals and Roundabout Metering Approach

Background and Objective: This study aims to improve the capacity and level of service at the sixth circle in Jordan by using traffic signals and a roundabout metering approach. Methods: VISSIM software and C++ program were used to improve the capacity and level of service. The site area (Sixth circle) was located near Crown Plaza and the Jordan Gate Towers project, which causes congestion due to heavy traffic flow. Therefore, this paper assesses the traffic in the sixth circle and presents the possible solutions to reduce the daily traffic flow for the users of this circle. Results: Four signals were placed at the roundabout in the second scenario, which was connected to each other with different cycle lengths. 90-second cycle length gives D value of the level of service. The third scenario was placed adaptive signals on the roundabout, which connects traffic signals with ground detectors placed at a certain distance before the signal and based on the queue length of the flow cars that pass the detector. Conclusion: The adaptive signals worked on the opening and closing and were designed according to the language simulation and the adoption of the language C++. The first two signals were opened considering the Swefieh road with the reference of King Faisal for a period of 45 seconds. It was then closed for 45 seconds to open the signal from the next street from the fifth circle with Zahran street.

Force Generation Profiles of Para-Nordic Sit-Skiers Representing Different Physical Impairments

Purpose To biomechanically profile force generation connected to the complex role of the trunk in double poling in a representative sample of Para-Nordic sit-skiers. Methods Twelve male World Cup Para-Nordic sit-skiers (sport classes: LW10–12) were skiing on flat snow terrain at submaximal speed of 4.5 m/s (~ 73% maximum speed). 2D video (50 Hz) and pole force analyses (1000 Hz) were performed synchronously, examining angle, force and cycle characteristics to analyse the role of the trunk in generating propulsion. Results LW10–11.5 skiers lost between 21% and 4% propulsive force versus LW12 athletes only due to different geometrics of the trunk and pole angle at an equal axial pole force. While LW10–11 skiers indicated trunk extension or position maintenance during pole thrust, LW11.5–12 skiers showed strong trunk flexion combined with smaller pole angles to the ground. Hence, LW11.5–12 skiers could create larger propulsive forces and therefore greater cycle lengths at lower cycle rates at the same speed. Maximum speed increased from LW10 to LW12 and was significantly correlated to trunk flexion range of motion (r = 0.63) and cycle length (r = 0.59). Trunk flexion ROM showed a significant relationship to the impulse of propulsive force (r = 0.63) and pole angle to the ground (r = − 0.76) (all P < 0.05). Conclusion The impact of impairment on the force production profiles and its physiological-biomechanical consequences need further investigation also in other terrains and at wider spectrums of skiing speeds. The evident problem of low numbers of LW10–11 skiers in World Cup needs creative future solutions for research.