Consistent Changes in the Circadian Rhythms of Blood Pressure and Atrial Natriuretic Peptide in Congestive Heart Failure

We demonstrated in previous works that the circadian rhythms of blood pressure (BP) and atrial natriuretic peptide (ANP) are antiphasic in normal subjects and in essential hypertension. The aim of the present study was to assess the circadian rhythms of BP and ANP in 20 patients with stable congestive heart failure (CHF), divided into two groups of 10 according to their New York Heart Association functional class. A matched control group of 10 normal volunteers was also studied. Noninvasive BP monitoring at 15-min intervals was performed for 24 h. Peripheral blood samples were also obtained at 4-h intervals starting from 08:OO h. The mean (±SEM) circadian mesors of ANP plasma levels were 13.4 ± 1.7 pmol/L in the control group, 28.6 ± 2.4 pmol/L in the group of 10 patients in class 11, and 81.5 ± 12 pmol/L in the group of 10 patients in class 111-IV. In normal subjects, plasma ANP concentration was highest at 04:OO h (21.5 ± 2.7 pmol/L) and lowest at 16:OO h (8.8 ± 2.4 pmol/L; p < 0.01). Both groups of patients with CHF showed no significant circadian change in the plasma levels of ANP and also a significantly blunted circadian rhythm of BP. Cosinor analysis confirmed the loss of the circadian rhythms of ANP and BP in CHF patients. Our findings support the existence of a causal relationship between the circadian rhythms of ANP and BP.     

PRESENCE OF CIRCADIAN RHYTHMS IN THE LOCOMOTOR ACTIVITY OF A CAVE-DWELLING MILLIPEDE GLYPHIULUS CAVERNICOLUS SULU (CAMBALIDAE,SPIROSTREPTIDA)

The locomotor activity of the millipede Glyphiulus cavernicolus (Spirostreptida), which occupies the deeper recesses of a cave, was monitored in light-dark (LD) cycles (12h light and 12h darkness), constant darkness (DD), and constant light (LL) conditions. These millipedes live inside the cave and are apparently never exposed to any periodic factors of the environment such as light-dark, temperature, and humidity cycles. The activity of a considerable fraction of these millipedes was found to show circadian rhythm, which entrained to a 12:12 LD cycle with maximum activity during the dark phase of the LD cycle. Under constant darkness (DD), 56.5% of the millipedes (n = 23) showed circadian rhythms, with average free-running period of 25.7h ± 3.3h (mean ± SD, range 22.3h to 35.0h). The remaining 43.5% of the millipedes, however, did not show any clear-cut rhythm. Under DD conditions following an exposure to LD cycles, 66.7% (n = 9) showed faint circadian rhythm, with average free-running period of 24.0h ± 0.8h (mean ± SD, range 22.9h to 25.2h). Under constant light (LL) conditions, only 2 millipedes of 11 showed free-running rhythms, with average period length of 33.3h ± 1.3h. The results suggest that these cave-dwelling millipedes still possess the capacity to measure time and respond to light and dark situations. (Chronobiology International, 17(6), 757–765, 2000)     

Internal coupling of five functions of rabbits exhibiting a bimodal circadian rhythm

Abstract

By means of a microcomputer‐assisted, electronic recording system five physiological, circadian rhythms of the rabbit were monitored: locomotor activity, hard faeces excretion, food intake, urine excretion and water intake.

During 120 days of continuous light conditions (30 lx) the animals exhibited a free‐running circadian rhythm. After the fading out of aftereffects of the preceding light: dark schedule on day 51 ± 11 the animals ran free with an individually distinct period length of > 24.0 h (τ: 24.48 ± 0.10 (SD) h). Spectral analysis of coherent data of 50–84 days showed that in addition to the circadian period persistent ultradian periods of 6.1, 8.2 and 12.3 h were present. Within each individual the five functions proved to be tightly coupled during the free‐run, during the time of reentrainment and when entrained with the LD 12:12. While during LD 12:12 the animals exhibited a bimodal rhythm, during the free‐run the rhythm was unimodal in all five functions. In one animal a “splitting”; of the free‐running period occurred. Both components ran free with different period length. They fused again after 38 days. The “splitting”; was reflected in all five functions of this animal.

The behavioural characteristics of meal duration and ‐frequency, duration of activity and ‐intervals, of water intake and urination did not show significant differences during the conditions of LD 12:12 and LL.

The results support Pittendrigh's model of two systems of oscillators, selectively susceptible to the transitions of dark : light and light : dark. Our results suggest that in the rabbit the five functions are governed in common by both oscillator‐systems.     

The influence of short-term sedentary behavior on circadian rhythm of heart rate and heart rate variability

The notion that sedentary behavior is harmful to human health is widespread. Little is known about the short term influence of sedentary behavior on heart rate (HR) and heart rate variability (HRV) circadian rhythms. Therefore the purpose of the present study was to examine the influence of short term sedentary behavior on the circadian rhythms of HR and HRV using cosine periodic regression analysis. Sixteen healthy young students were included in a randomized crossover study. All subjects underwent 24-h ECG Holter monitoring in two different states of physical activity, an active condition (more than 15,000 steps per day) and a sedentary condition (less than 1,000 steps per day). Hourly mean values were calculated for HR and HRV, and then were evaluated using cosine periodic regression analysis. The circadian rhythm parameters, amplitude, mesor, and acrophase for HR and HRV variables were obtained. As a result, the significance of the circadian rhythm was confirmed for all variables in each condition. The measure of fit R2 value was decreased in sedentary condition. The amplitude of the sedentary condition was significantly smaller than that of the active condition with respect to HR (7.94 ± 1.91 bpm vs. 15.4 ± 3.93 bpm, p < 0.001), natural log of the high frequency measurement (lnHF) (0.38 ± 0.21 ms2 vs. 0.80 ± 0.28 ms2, p < 0.001), and low frequency/high frequency ratio (LF/HF) (0.75 ± 0.54 vs. 1.24 ± 0.69, p = 0.008). We found that sedentary behavior not only significantly lowered the amplitude of HR and HRV variables, but also might have led to weakness of the circadian rhythm of the HR and HRV variables.     

Multi-Oscillatory Control of Eclosion and Oviposition Rhythms in Drosophila melanogaster: Evidence from Limits of Entrainment Studies

The eclosion and oviposition rhythms of flies from a population of Drosophila melanogaster maintained under constant conditions of the laboratory were assayed under constant light (LL), constant darkness (DD), and light/dark (LD) cycles of 10:10 h (T20), 12:12 h (T24), and 14:14 h (T28). The mean (±95% confidence interval; CI) free-running period (τ) of the oviposition rhythm was 26.34 ± 1.04 h and 24.50 ± 1.77 h in DD and LL, respectively. The eclosion rhythm showed a τ of 23.33 ± 0.63 h (mean ± 95% CI) in DD, and eclosion was not rhythmic in LL. The τ of the oviposition rhythm in DD was significantly greater than that of the eclosion rhythm. The eclosion rhythm of all 10 replicate vials entrained to the three periodic light regimes, T20, T24, and T28, whereas the oviposition rhythm of only about 24 and 41% of the individuals entrained to T20 and T24 regimes, respectively, while about 74% of the individuals assayed in T28 regimes showed entrainment. Our results thus clearly indicate that the τ and the limits of entrainment of eclosion rhythm are different from those of the oviposition rhythm, and hence this reinforces the view that separate oscillators may regulate these two rhythms in D. melanogaster.     

Comparative life cycle assessment of smartphone reuse: repurposing vs. refurbishment

Purpose

Waste management for end-of-life (EoL) smartphones is a growing problem due to their high turnover rate and concentration of toxic chemicals. The versatility of modern smartphones presents an interesting alternative waste management strategy: repurposing. This paper investigates the environmental impact of smartphone repurposing as compared to traditional refurbishing using Life Cycle Assessment (LCA).

Methods

A case study of repurposing was conducted by creating a smartphone “app” that replicates the functionality of an in-car parking meter. The environmental impacts of this prototype were quantified using waste management LCA methodology. Studied systems included three waste management options: traditional refurbishment, repurposing using battery power, and repurposing using a portable solar charger. The functional unit was defined as the EoL management of a used smartphone. Consequential system expansion was employed to account for secondary functions provided; avoided impacts from displaced primary products were included. Impacts were calculated in five impact categories. Break-even displacement rates were calculated and sensitivity to standby power consumption were assessed.

Results and discussion

LCA results showed that refurbishing creates the highest environmental impacts of the three reuse routes in every impact category except ODP. High break-even displacement rates suggest that this finding is robust within a reasonable range of primary cell phone displacement. The repurposed smartphone in-car parking meter had lower impacts than the primary production parking meter. Impacts for battery-powered devices were dominated by use-phase charging electricity, whereas solar-power impacts were concentrated in manufacturing. Repurposed phones using battery power had lower impacts than those using solar power, however, standby power sensitivity analysis revealed that solar power is preferred if the battery charger is left plugged-in more than 20 % of the use period.

Conclusions

Our analysis concludes that repurposing represents an environmentally preferable EoL option to refurbishing for used smartphones. The results suggest two generalizable findings. First, primary product displacement is a major factor affecting whether any EoL strategy is environmentally beneficial. The benefit depends not only on what is displaced, but also on how much displacement occurs; in general, repurposing allows freedom to target reuse opportunities with high “displacement potential.” Second, the notion that solar power is preferable to batteries is not always correct; here, the rank-order is sensitive to assumptions about user behavior.     

Stability and Fragmentation of the Activity Rhythm Across the Sleep-Wake Cycle: The Importance of Age,Lifestyle, and Mental Health

The rhythms of activity across the 24-h sleep-wake cycle, determined in part by the circadian clock, change with aging. Few large-scale studies measured the activity rhythm objectively in the general population. The present population-based study in middle-aged and elderly persons evaluated how activity rhythms change with age, and additionally investigated sociodemographics, mental health, lifestyle, and sleep characteristics as determinants of rhythms of activity. Activity rhythms were measured objectively with actigraphy. Recordings of at least 96?h (138?±?14?h, mean?±?SD) were collected from 1734 people (age: 62?±?9.4?yrs) participating in the Rotterdam Study. Activity rhythms were quantified by calculating interdaily stability, i.e., the stability of the rhythm over days, and intradaily variability, i.e., the fragmentation of the rhythm relative to its 24-h amplitude. We assessed age, gender, presence of a partner, employment, cognitive functioning, depressive symptoms, body mass index (BMI), coffee use, alcohol use, and smoking as determinants. The results indicate that older age is associated with a more stable 24-h activity profile (β?=?0.07, p?=?0.02), but also with a more fragmented distribution of periods of activity and inactivity (β?=?0.20, p?<?0.001). Having more depressive symptoms was related to less stable (β?=??0.07, p?=?0.005) and more fragmented (β?=?0.10, p?<?0.001) rhythms. A high BMI and smoking were also associated with less stable rhythms (BMI: β?=??0.11, p?<?0.001; smoking: β?=??0.11, p?<?0.001) and more fragmented rhythms (BMI: β?=?0.09, p?<?0.001; smoking: β?=?0.11, p?<?0.001). We conclude that with older age the 24-h activity rhythm becomes more rigid, whereas the ability to maintain either an active or inactive state for a longer period of time is compromised. Both characteristics appear to be important for major health issues in old age.     

Change of serum mitochondrial uncoupling protein 1 (UCP1) levels and daily rhythm of rectal and cutaneous temperatures in Equus caballus and Capra hyrcus

The aim of the present study was to monitor the daily rhythm of rectal and cutaneous temperatures together with the changes in the serum levels of mitochondrial uncoupling protein 1 (UCP1) in equine and goat species. On five gelding horses and five female goat rectal and cutaneous temperatures were recorded at 4 h intervals for a 48 h period. At the same time points blood samples were collected from each animal. Daily rhythms of rectal and cutaneous temperatures were observed in both species, in both day of monitoring. Mesor value of rectal temperature was statistically higher of about 4 °C than cutaneous temperature, and acrophase was postponed of about 2 h in both day of monitoring and in both species. UCP1 did not show daily rhythmicity in horses and goats. We can speculate that the thermogenesis due to thermal system is auxiliary to keeping the body temperature daily rhythm.     

Taking a Call Is Facilitated by the Multisensory Processing of Smartphone Vibrations,Sounds, and Flashes

Many electronic devices that we use in our daily lives provide inputs that need to be processed and integrated by our senses. For instance, ringing, vibrating, and flashing indicate incoming calls and messages in smartphones. Whether the presentation of multiple smartphone stimuli simultaneously provides an advantage over the processing of the same stimuli presented in isolation has not yet been investigated. In this behavioral study we examined multisensory processing between visual (V), tactile (T), and auditory (A) stimuli produced by a smartphone. Unisensory V, T, and A stimuli as well as VA, AT, VT, and trisensory VAT stimuli were presented in random order. Participants responded to any stimulus appearance by touching the smartphone screen using the stimulated hand (Experiment 1), or the non-stimulated hand (Experiment 2). We examined violations of the race model to test whether shorter response times to multisensory stimuli exceed probability summations of unisensory stimuli. Significant violations of the race model, indicative of multisensory processing, were found for VA stimuli in both experiments and for VT stimuli in Experiment 1. Across participants, the strength of this effect was not associated with prior learning experience and daily use of smartphones. This indicates that this integration effect, similar to what has been previously reported for the integration of semantically meaningless stimuli, could involve bottom-up driven multisensory processes. Our study demonstrates for the first time that multisensory processing of smartphone stimuli facilitates taking a call. Thus, research on multisensory integration should be taken into consideration when designing electronic devices such as smartphones.     

Effect of sleep deprivation on rhythms of clock gene expression and melatonin in humans

This study investigated the impact of sleep deprivation on the human circadian system. Plasma melatonin and cortisol levels and leukocyte expression levels of 12 genes were examined over 48?h (sleep vs. no-sleep nights) in 12 young males (mean?±?SD: 23?±?5 yrs). During one night of total sleep deprivation, BMAL1 expression was suppressed, the heat shock gene HSPA1B expression was induced, and the amplitude of the melatonin rhythm increased, whereas other high-amplitude clock gene rhythms (e.g., PER1-3, REV-ERBα) remained unaffected. These data suggest that the core clock mechanism in peripheral oscillators is compromised during acute sleep deprivation.     

Circadian rhythm in QT interval is preserved in mice deficient of potassium channel interacting protein 2

Potassium Channel Interacting Protein 2 (KChIP2) is suggested to be responsible for the circadian rhythm in repolarization duration, ventricular arrhythmias, and sudden cardiac death. We investigated the hypothesis that there is no circadian rhythm in QT interval in the absence of KChIP2. Implanted telemetric devices recorded electrocardiogram continuously for 5 days in conscious wild-type mice (WT, n = 9) and KChIP2^?/? mice (n = 9) in light:dark periods and in complete darkness. QT intervals were determined from all RR intervals and corrected for heart rate (QT₁₀₀ = QT/(RR/100)^1/2). Moreover, QT intervals were determined from complexes within the RR range of mean-RR ± 1% in the individual mouse (QT_mean-RR). We find that RR intervals are 125 ± 5 ms in WT and 123 ± 4 ms in KChIP2^?/? (p = 0.81), and QT intervals are 52 ± 1 and 52 ± 1 ms, respectively(p = 0.89). No ventricular arrhythmias or sudden cardiac deaths were observed. We find similar diurnal (light:dark) and circadian (darkness) rhythms of RR intervals in WT and KChIP2^?/? mice. Circadian rhythms in QT₁₀₀ intervals are present in both groups, but at physiological small amplitudes: 1.6 ± 0.2 and 1.0 ± 0.3 ms in WT and KChIP2^?/?, respectively (p = 0.15). A diurnal rhythm in QT₁₀₀ intervals was only found in WT mice. QT_mean-RR intervals display clear diurnal and circadian rhythms in both WT and KChIP2^?/?. The amplitude of the circadian rhythm in QT_mean-RR is 4.0 ± 0.3 and 3.1 ± 0.5 ms in WT and KChIP2^?/?, respectively (p = 0.16). In conclusion, KChIP2 expression does not appear to underlie the circadian rhythm in repolarization duration.     

Defining the substrate for ventricular tachycardia ablation: The impact of rhythm at the time of mapping

BackgroundVoltage mapping is critical to define substrate during ablation. In ventricular tachycardia, abnormal potentials may be targets. However, wavefront of activation could impact local signal characteristics. This may be particularly true when comparing sinus rhythm versus paced rhythms. We sought to determine how activation wavefront impacts electrogram characteristics.MethodsPatients with ischemic cardiomyopathy, ventricular tachycardia, and without fascicular or bundle branch block were included. Point by point mapping was done and at each point, one was obtained during an atrial paced rhythm and one during a right ventricular paced rhythm. Signals were adjudicated after ablation to define late potentials, fractionated potentials, and quantify local voltage. Areas of abnormal voltage (defined as <1.5 mV) were also determined.Results9 patients were included (age 61.3 ± 9.2 years, 56% male, mean LVEF 34.9 ± 8.6%). LV endocardium was mapped with an average 375 ± 53 points/rhythm. Late potentials were more frequent during right ventricular pacing (51 ± 21 versus 32 ± 15, p < 0.01) while overall scar area was higher during atrial pacing (22 ± 11% vs 13 ± 7%, p < 0.05). In 1/9 patients, abnormal potentials were seen during a right ventricular paced rhythm that were not apparent in an atrial paced rhythm, ablation of which resulted in non-inducibility.ConclusionRhythm in which mapping is performed has an impact on electrogram characteristics. Whether one rhythm is preferable to map in remains to be determined. However, it is possible defining local signals during normal conduction as well as variable paced rhythms may impart a greater likelihood of elucidating arrhythmogenic substrate.     

Effect of thermoperiod amplitude on the adult eclosion rhythm of Indian meal moth,Plodia interpunctella (Lepidoptera: Pyralidae)

The thermoperiodic time cue is known to be one of several zeitgebers (Zt) that entrain an organism's biological rhythms. This study investigated the adult eclosion rhythm of the Indian meal moth, Plodia interpunctella, (Lepidoptera: Pyralidae) under various thermocycles in constant darkness. The insects were exposed to different thermoperiods (e.g. 25.5°C/24.5°C). Thermophase : cryophase ratios (TC) ranged from 4 h : 20 h to 20 h : 4 h. The peak in adult eclosion rhythm occurred at Zt 18.8 ± 4.4 (mean ± SD) on a given day and at Zt 0.7 ± 3.8 on the subsequent day under TC 4 h : 20 h and TC 20 h : 4 h conditions, respectively (start of temperature increase = Zt 0). Thus, longer thermophase periods delayed the peak in eclosion. The regression line obtained was then compared with that obtained under the temperature cycle of 30°C/20°C, and the two lines were found to lie parallel to each other. The peak in adult eclosion rhythm occurred earlier under the 25.5°C/24.5°C conditions than under the 30°C/20°C conditions. The results strongly suggest that the amplitude of the temperature cycle is an important factor determining the temporal position of the peak in adult eclosion. This is a significant finding among insect species.     

动物内源褪黑素调控生物节律的研究进展

内源褪黑素对人类和其他哺乳动物的节律行为具有调控功能。生物节律是自然进化赋予生命的基本特征之一,生物体的生命活动受到生物节律的控制与影响。在哺乳动物中,节律调控中心是松果体,其主要功能是合成和分泌褪黑素。褪黑素广泛参与生物体节律行为的调节,本文从褪黑素的产生和作用机制,分别阐述褪黑素对昼夜节律行为和多种年节律行为的调控作用,同时明确褪黑素与生物钟及神经内分泌系统的直接作用和反馈互动的复杂集合,进一步揭示褪黑素调控生物节律的重要作用,以期为褪黑素的基础研究以及未来探究生物体的生物钟内源性发生机制提供参考。     

Development and relationships of locomotor, feeding, and oxygen consumption rhythms in house crickets

ABSTRACT. Locomotor, feeding, drinking, and oxygen consumption rhythms in adult virgin Acheta domesticus L. all appear to peak in the first half of the scotophase, be entrained cophasically by a LD 14:10 h cycle, have a lights-off Zeitgeber and persist in LL with a π c. 25 h for the locomotor rhythm and c. 23 h for the oxygen consumption rhythm. There is no evidence of these rhythms in last instar larvae. The onset of the locomotor rhythm requires 3 days at 30°C but 5–7 days at 25–28°C after the final ecdysis in virgins, indicating a temperature related development of the locomotor rhythm. Oxygen consumption rhythms are lacking in 2-day-old virgins but present in 8-day-old virgins. Feeding rhythms can be recorded in virgins as young as 2 days (before locomotor rhythm developed). Both oxygen consumption and locomotor rhythms persist during starvation. The results suggest that a central brain oscillator drives both feeding and locomotor rhythms independently, but that the oxygen consumption rhythm is derived from the metabolic demands associated with the other rhythms.     

An Inbred Lineage of Djungarian Hamsters with a Strongly Attenuated Ability to Synchronize

An inbred lineage of Ph. sungorus was established at our institute showing some unusual characteristics of the circadian system that appear incompatible with an adequate adaptation to the periodic environment. We identified a hamster for which activity onset was delayed under light‐dark conditions (L:D=14∶10 h) by about 4 h in relation to the light‐dark transition. As the activity offset remained synchronized with the time of light‐on, the activity period (α) became compressed to 6 h. By means of a special breeding program, the percentage of animals showing such a phenomenon increased, indicating that it has a genetic component. Also, it is possible now to breed a larger number of hamsters to further investigate the rhythm deviations and the underlying mechanisms. Activity rhythms were investigated using passive infrared motion sensors. Whereas some of the hamsters showed a rather stable phase delay of activity onset relative to the onset of darkness, some animals progressively delayed their activity onset up to a critical, minimal length of α (3.03±0.02 h). Thereafter, the rest‐activity rhythm started to free‐run with a remarkably long period (τ=25.02 h) or became arrhythmic. Some hamsters showed several consecutive cycles alternating between a free‐running rhythm and entrainment, with increasing τ and reducing the phases of temporary entrainment. Finally, these hamsters became arrhythmic. The total amount of activity per day was similar in the wild type and delayed activity onset hamsters. The latter did increase the intensity of activity, thereby compensating for the shorter α. The period length in constant darkness was significantly longer in the delayed hamsters compared to wild type animals (24.37±0.03 h vs. 24.24±0.02 h; p<0.001). However, this difference seems too small to cause the later activity onset. The phase response following a light pulse (100 lux, 15′ at CT14 where CT12=activity onset) was similar in delayed and wild type hamsters (?1.66±0.12 h and ?1.82±0.16 h). As access to running wheels is known to influence the circadian pacemaker, particularly to strengthen oscillator coupling, a set of further experiments was conducted. The free‐running period was significantly shorter when the hamsters were provided with running wheels (24.25±0.04 h and 24.07±0.04 h in wild type and delayed hamsters, respectively; p<0.005 and p<0.05). However, the effect on the activity onset was not unequivocal. In many hamsters it was still delayed, whereas in others the unlocking of the wheels led to an expansion of α. The described inbred lineage appears to be an excellent model to further investigate the properties and the interaction of the two oscillators underlying the daily activity pattern.     

Passive acoustic monitoring reveals group ranging and territory use: a case study of wild chimpanzees (<Emphasis Type="Italic">Pan troglodytes</Emphasis>)

Background

Assessing the range and territories of wild mammals traditionally requires years of data collection and often involves directly following individuals or using tracking devices. Indirect and non-invasive methods of monitoring wildlife have therefore emerged as attractive alternatives due to their ability to collect data at large spatiotemporal scales using standardized remote sensing technologies. Here, we investigate the use of two novel passive acoustic monitoring (PAM) systems used to capture long-distance sounds produced by the same species, wild chimpanzees (Pan troglodytes), living in two different habitats: forest (Taï, Côte d’Ivoire) and savanna-woodland (Issa valley, Tanzania).

Results

Using data collected independently at two field sites, we show that detections of chimpanzee sounds on autonomous recording devices were predicted by direct and indirect indices of chimpanzee presence. At Taï, the number of chimpanzee buttress drums detected on recording devices was positively influenced by the number of hours chimpanzees were seen ranging within a 1 km radius of a device. We observed a similar but weaker relationship within a 500 m radius. At Issa, the number of indirect chimpanzee observations positively predicted detections of chimpanzee loud calls on a recording device within a 500 m but not a 1 km radius. Moreover, using just seven months of PAM data, we could locate two known chimpanzee communities in Taï and observed monthly spatial variation in the center of activity for each group.

Conclusions

Our work shows PAM is a promising new tool for gathering information about the ranging behavior and habitat use of chimpanzees and can be easily adopted for other large territorial mammals, provided they produce long-distance acoustic signals that can be captured by autonomous recording devices (e.g., lions and wolves). With this study we hope to promote more interdisciplinary research in PAM to help overcome its challenges, particularly in data processing, to improve its wider application.

     

A modified regimen of extracorporeal cardiac shock wave therapy for treatment of coronary artery disease

Background

Radiofrequency catheter ablation of atrial fibrillation (AF) has been proved to be effective and to prevent progressive left atrial (LA) remodeling. Cryoballoon catheter ablation (CCA), using a different energy source, was developed to simplify the ablation procedure. Our hypothesis was that successful CCA can also prevent progressive LA remodeling.

Methods

36 patients selected for their first CCA because of nonvalvular paroxysmal AF had echocardiography before and 3, 6 and 12 months after CCA. LA diameters, volumes (LAV) and LA volume index (LAVI) were evaluated. LA function was assessed by: early diastolic velocities of the mitral annulus (Aa_sept, Aa_lat), LA filling fraction (LAFF), LA emptying fraction (LAEF) and the systolic fraction of pulmonary venous flow (PVSF). Detailed left ventricular diastolic function assessment was also performed.

Results

Excluding recurrences in the first 3-month blanking period, the clinical success rate was 64%. During one-year of follow-up, recurrent atrial arrhythmia was found in 21 patients (58%). In the recurrent group at 12 months after ablation, minimal LAV (38 ± 19 to 44 ± 20 ml; p < 0.05), maximal LAV (73 ± 23 to 81 ± 24 ml; p < 0.05), LAVI (35 ± 10 to 39 ± 11 ml/m²; p = 0.01) and the maximal LA longitudinal diameter (55 ± 5 to 59 ± 6 mm; p < 0.01) had all increased. PVSF (58 ± 9 to 50 ± 10%; p = 0.01) and LAFF (36 ± 7 to 33 ± 8%; p = 0.03) had decreased. In contrast, after successful cryoballoon ablation LA size had not increased and LA function had not declined. In the recurrent group LAEF was significantly lower at baseline and at follow-up visits.

Conclusions

In patients whose paroxysmal atrial fibrillation recurred within one year after cryoballoon catheter ablation left atrial size had increased and left atrial function had declined. In contrast, successful cryoballoon catheter ablation prevented progressive left atrial remodeling.     

Circadian variations in self-monitoring,a component of executive functions

The objective of this study was to identify circadian rhythms in self-monitoring, a component of executive functions. Participants were 10 undergraduate students, age: 18.5 ± 2.68 years, two male and eight female. They were recorded on a 30-h constant routine protocol; rectal temperature was recorded every minute and performance on a tracking task was assessed every 100 min. Self-monitoring indicators were adjustments of responses to random changes of speed and trajectory of a circle moving on the computer screen. Participants showed better accuracy during the afternoon, with decreases in the morning (06:20 and 08:00 h). These variations showed a phase delay of 2:29 ± 2:19 h with respect to the circadian rhythm of body temperature. In conclusion, there are circadian variations in self-monitoring. The decline in this component of executive functions could cause serious accidents among people working or studying during a morning shift, as well as commuting to and from work or school.