Circadian Rhythm in Sudden Cardiac Death: A Retrospective Study of 2,665 Cases

Measuring honey bee feeding rhythms with the BeeBox, a platform for nectar foraging insects

In honey bees, most studies of circadian rhythms involve a locomotion test performed in a small tube, a tunnel, or at the hive entrance. However, despite feeding playing an important role in honey bee health or fitness, no demonstration of circadian rhythm on feeding has been performed until recently. Here, we present the BeeBox, a new laboratory platform for bees based on the concept of the Skinner box, which dispenses discrete controlled amounts of food (sucrose syrup) following entrance into an artificial flower. We compared caged groups of bees in 12 h-12 h light/dark cycles, constant darkness and constant light and measured average hourly syrup consumption per living bee. Food intake was higher in constant light and lower in constant darkness; mortality increased in constant light. We observed rhythmic consumption with a period longer than 24 h; this is maintained in darkness without environmental cues, but is damped in the constant light condition. The BeeBox offers many new research perspectives and numerous potential applications in the study of nectar foraging animals.

Short-term exposures to temperature and risk of sudden cardiac death in women: A case-crossover analysis in the Nurses' Health Study

Background

Sudden cardiac death (SCD) is a major source of mortality and is the first manifestation of heart disease for most cases. Thus, there is a definite need to identify risk factors for SCD that can be modified on the population level. Short-term exposures to temperature have been implicated as a potential risk factor. Our objective was to determine if short-term temperature exposures were associated with increased risk of SCD in a US-based time-stratified case-crossover study.

Methods

A total of 465 cases of SCD were identified among participants of the prospective Nurses' Health Study (NHS). Control days were selected from all other matching days of the week within the same month as the case day. Average ambient temperature on the current day (Lag0) and preceding 27 days (Lags1-27) was determined at the residence level using 800-m resolution estimates. Conditional logistic distributed lag nonlinear models (DLNMs) were used to assess the relative risk (RR) of the full range of temperature exposures over the lag period.

Results

Warmer exposures in the days before event and colder temperatures 21-28 days prior were associated with increased risks of SCD. These results were driven by associations in regions other than the Northeast and among married women.

Conclusions

Both warm and cold ambient temperatures are suggestively associated with risks of SCD among middle-aged and older women living across the United States.

Biological rhythms of fatal myocardial infarction in Greece: an autopsy study

BACKGROUND

Biological rhythms, acting as an endogenous clock, prepare and assist the organism to function optimally during predictable seasonal and daily cycles. Many elements of the cardiovascular system exhibit specific rhythmical patterns. Besides genetic mechanisms, external stimuli may alter biological rhythms.

METHODS

The aim of this study was to investigate the patterns of biological rhythms in patients who suffered a fatal myocardial Infarction (MI), ascertained by macroscopical or histopathological examination. Cases of fatal MI examined during the time 2010-2017 were included in our study sample (827 cases in total). Medical History was also obtained for each case. The assessment of seasonal variation of fatal MI was accomplished by employing three different methods, Rayleigh Uniformity Test, X² Goodness-of-fit test and Edward's Seasonality Test. Statistical significance was defined as a 2-sided p value of <0.05.

RESULTS

Regarding the distribution of total cases, fatal MIs onset occurs more often during winter, with higher incidence in December and January. The weekly distribution of cases seems uniform. The circadian pattern presents higher frequencies of fatal MIs between 08:00 and 12:00 with the acrophase between 11:00 and 12:00. Further analysis was conducted separately, depending on the method of time-of-death reporting.

CONCLUSIONS

Taking under consideration the variation of the occurrence of MI related deaths, in accordance with the respective biological rhythms, public health policies more suitable to the individual requirements of every country's population may be adopted.

Clocks, Rhythms, Sex, and Hearts: How Disrupted Circadian Rhythms, Time-of-Day, and Sex Influence Cardiovascular Health

Cardiovascular diseases are the top cause of mortality in the United States, and ischemic heart disease accounts for 16% of all deaths around the world. Modifiable risk factors such as diet and exercise have often been primary targets in addressing these conditions. However, mounting evidence suggests that environmental factors that disrupt physiological rhythms might contribute to the development of these diseases, as well as contribute to increasing other risk factors that are typically associated with cardiovascular disease. Exposure to light at night, transmeridian travel, and social jetlag disrupt endogenous circadian rhythms, which, in turn, alter carefully orchestrated bodily functioning, and elevate the risk of disease and injury. Research into how disrupted circadian rhythms affect physiology and behavior has begun to reveal the intricacies of how seemingly innocuous environmental and social factors have dramatic consequences on mammalian physiology and behavior. Despite the new focus on the importance of circadian rhythms, and how disrupted circadian rhythms contribute to cardiovascular diseases, many questions in this field remain unanswered. Further, neither time-of-day nor sex as a biological variable have been consistently and thoroughly taken into account in previous studies of circadian rhythm disruption and cardiovascular disease. In this review, we will first discuss biological rhythms and the master temporal regulator that controls these rhythms, focusing on the cardiovascular system, its rhythms, and the pathology associated with its disruption, while emphasizing the importance of the time-of-day as a variable that directly affects outcomes in controlled studies, and how temporal data will inform clinical practice and influence personalized medicine. Finally, we will discuss evidence supporting the existence of sex differences in cardiovascular function and outcomes following an injury, and highlight the need for consistent inclusion of both sexes in studies that aim to understand cardiovascular function and improve cardiovascular health.

Circadian Rhythms in Sudden Cardiac Arrest: A Review

BACKGROUND

Sudden cardiac arrest (SCA) is a serious public health issue caused by the cessation of cardiac electrical and mechanical activity. Despite advances in pedestrian lifesaving technologies like defibrillators, the SCA mortality rate remains high, and survivors are at risk of suffering ischemic injury to various organs. Understanding the contributing factors for SCA is essential for improving morbidity and mortality. One factor capable of influencing SCA incidence and survival is the time of day at which SCA occurs.

OBJECTIVES

This review focused on the effect of time of day on SCA incidence, survival rate, and survival to discharge over the past 30 years and the role of age, sex, and SCA location in modulating the timing of SCA.

METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews criteria guided this review. Four databases (PubMed, Cochrane Libraries, Scopus, and Cumulative Index to Nursing and Allied Health Literature) were queried for research reports or articles addressing time of day and cardiac arrest, which were subsequently screened by the authors for inclusion in this analysis.

RESULTS

A total of 48 articles were included in the final analysis. This analysis showed a bimodal SCA distribution with a primary peak in the morning and a secondary peak in the afternoon; these peaks were dependent on age (older persons), sex (more frequent in males), and the location of occurrence (out-of-hospital cardiac arrest vs. in-hospital cardiac rest). Survival following SCA was lowest between midnight and 06:00 a.m.

DISCUSSION

The circadian rhythm likely plays an important role in the time-of-day-dependent pattern that is evident in both the incidence of and survival following SCA. There is a renewed call for nursing research to examine or address circadian rhythm as an element in studies involving older adults and activities affecting cardiovascular or respiratory parameters.

Identification of a morning out-of-hospital cardiac arrest cluster of high-incidence: towards a chrono-preventive care strategy

RATIONALE, AIMS, AND OBJECTIVES

The human body is regulated by intrinsic factors which follow a 24-hour biological clock. Implications of a circadian rhythm in the out-of-hospital cardiac arrest (OHCA) are studied but the literature is not consistent. The main objective of our study was to identify temporal cluster of high or low incidence of OHCA occurrence during a day.

METHODS

Multicentre comparative study based on the French national OHCA registry data between 2013 and 2017. After describing the population, the detection of significant temporal clusters of OHCA incidence was achieved using temporal scan statistics based on a Poisson model adjusted for age and gender. Then, comparisons between identified patients clusters and the rest of the population were performed.

RESULTS

During the study, 37 163 medical OHCA victims were included. The temporal scan revealed a significant 3-hour high incidence temporal cluster between 8:00 am and 10:59 am (Relative R = 1.76, P < .001). In the identified cluster, OHCA occurred more out of the home with fewer witnesses, and advanced life support was less attempted in the cluster. No difference was observed on the return of spontaneous circulation, survival at hospital admission, and survival 30 days after the OHCA or at hospital discharge.

CONCLUSIONS

We observed a three-hour morning high incidence peak of OHCA. This high incidence could be explained by different physiological changes in the morning. These changes are well known and the evidence of a morning peak of cardiovascular disease should enable medical teams to adapt care strategy and hospital organization.

Circadian Pattern of Acute Myocardial Infarction and Atrial Fibrillation in a Mediterranean Country: A study in Diabetic Patients

Background and objectives: The circadian pattern seems to play a crucial role in cardiovascular events and arrhythmias. Diabetes mellitus is a complex metabolic disorder associated with autonomic nervous system alterations and increased risk of microvascular and macrovascular disease. We sought to determine whether acute myocardial infarction (AMI) and atrial fibrillation (AF) follow a circadian pattern in diabetic patients in a Mediterranean country. Materials and Methods: This retrospective study included 178 diabetic patients (mean age: 67.7) with AMI or AF who were admitted to the coronary care unit. The circadian pattern of AMI and AF was identified in the 24-h period (divided in 3-h and 1-h intervals). Patients were also divided in 3 groups according to age; 40-65 years, 66-79 years and patients older than 80 years. A chi-square goodness-of-fit test was used for the statistical analysis. Results: AMI seems to occur more often in the midnight hours (21:00-23:59) (p < 0.001). Regarding age distribution, patients between 40 and 65 years were more likely to experience an AMI compared to other age groups (p < 0.001). Autonomic alterations, working habits, and social reasons might contribute to this phenomenon. AF in diabetic patients occurs more frequently at noon (12:00-14:59) (p = 0.019). Conclusions: Diabetic patients with AMI and AF seem to follow a specific circadian pattern in a Mediterranean country, with AMI occurring most often at midnight hours and AF mostly at noon. Autonomic dysfunction, glycemic fluctuations, intense anti-diabetic treatment before lunch, and patterns of insulin secretion and resistance may explain this pattern. More studies are needed to elucidate the circadian pattern of AMI and AF in diabetic patients to contribute to the development of new therapeutic approaches in this setting.

Spatial-time analysis of cardiovascular emergency medical requests: enlightening policy and practice

Background

Response time to cardiovascular emergency medical requests is an important indicator in reducing cardiovascular disease (CVD) -related mortality. This study aimed to visualize the spatial-time distribution of response time, scene time, and call-to-hospital time of these emergency requests. We also identified patterns of clusters of CVD-related calls.

Methods

This cross-sectional study was conducted in Mashhad, north-eastern Iran, between August 2017 and December 2019. The response time to every CVD-related emergency medical request call was computed using spatial and classical statistical analyses. The Anselin Local Moran’s I was performed to identify potential clusters in the patterns of CVD-related calls, response time, call-to-hospital arrival time, and scene-to-hospital arrival time at small area level (neighborhood level) in Mashhad, Iran.

Results

There were 84,239 CVD-related emergency request calls, 61.64% of which resulted in the transport of patients to clinical centers by EMS, while 2.62% of callers (a total of 2218 persons) died before EMS arrival. The number of CVD-related emergency calls increased by almost 7% between 2017 and 2018, and by 19% between 2017 and 2019. The peak time for calls was between 9 p.m. and 1 a.m., and the lowest number of calls were recorded between 3 a.m. and 9 a.m. Saturday was the busiest day of the week in terms of call volume. There were statistically significant clusters in the pattern of CVD-related calls in the south-eastern region of Mashhad. Further, we found a large spatial variation in scene-to-hospital arrival time and call-to-hospital arrival time in the area under study.

Conclusion

The use of geographical information systems and spatial analyses in modelling and quantifying EMS response time provides a new vein of knowledge for decision makers in emergency services management. Spatial as well as temporal clustering of EMS calls were present in the study area. The reasons for clustering of unfavorable time indices for EMS response requires further exploration. This approach enables policymakers to design tailored interventions to improve response time and reduce CVD-related mortality.

Circadian Rhythm of Deaths in a Cardiology Department: A Five-Year Analysis

BACKGROUND

Previous studies have described a circadian pattern of death from cardiovascular causes with a morning peak. Our aim is to describe the daytime oscillations in mortality in hospitalized patients with cardiovascular diseases.

METHODS

Our retrospective registry including all patients who died in the Cardiology Department, including the cardiac intensive care unit, Madrid, Spain.

RESULTS

From a total of 500 patients, time of death was registered in 373 (74.6%), which are the focus of our study; 354 (70.8%) died in the cardiac intensive care unit and 146 (29.2%) in the conventional ward. Mean age was 74.2 ± 13.1 years, and 239 (64.1%) were male. Cardiovascular causes were the leading cause of death (308 patients; 82.6%). Mortality followed a circadian biphasic pattern with a peak at dawn (00.00-05.59 a.m.: 104 patients [27.9%]) and in the afternoon (12.00-17.59 p.m.: 135 patients [36.2%]), irrespective of the cause of death. The peak of mortality occurred in the afternoon (12.00-17.59 p.m.) in the case of cardiovascular mortality (119 deaths [38.6%]) and in the evening (18.00-23.59 p.m.) for non-cardiovascular deaths (21 deaths [32.3%], p = 0.03). This pattern was present regardless from the place of death (conventional ward or cardiac intensive care unit) and also throughout the four seasons.

CONCLUSIONS

Mortality in hospitalized patients with cardiovascular diseases follows a circadian biphasic pattern.

High Incidence and Mortality of Out-of-Hospital Cardiac Arrest on Traditional Holiday in South Korea

BACKGROUND AND OBJECTIVES

This study aimed to confirm the effects of traditional holidays on the incidence and outcomes of out-of-hospital cardiac arrest (OHCA) in South Korea.

METHODS

We studied 95,066 OHCAs of cardiac cause from a nationwide, prospective study from the Korea OHCA Registry from January 2012 to December 2016. We compared the incidence of OHCA, in-hospital mortality, and neurologic outcomes between traditional holidays, Seollal (Lunar New Year's Day) and Chuseok (Korean Thanksgiving Day), and other day types (weekday, weekend, and public holiday).

RESULTS

OHCA occurred more frequently on traditional holidays than on the other days. The median OHCA incidence were 51.0 (interquartile range [IQR], 44.0-58.0), 53.0 (IQR, 46.0-60.5), 52.5 (IQR, 45.3-59.8), and 60.0 (IQR, 52.0-69.0) cases/day on weekday, weekend, public holiday, and traditional holiday, respectively (p<0.001). The OHCA occurred more often at home rather than in public place, lesser bystander cardiopulmonary resuscitation (CPR) was performed, and the rate of cessation of CPR within 20 minutes without recovery of spontaneous circulation was higher on traditional holiday. After multivariable adjustment, traditional holiday was associated with higher in-hospital mortality (adjusted hazard ratio [HR], 1.339; 95% confidence interval [CI], 1.058-1.704; p=0.016) but better neurologic outcomes (adjusted HR, 0.503; 95% CI, 0.281-0.894; p=0.020) than weekdays.

CONCLUSIONS

The incidence of OHCAs was associated with day types in a year. It occurred more frequently on traditional holidays than on other day types. It was associated with higher in-hospital mortality and favorable neurologic outcomes than weekday.

Unexpected shift in circadian and septadian variation of sudden cardiac arrest: the Oregon Sudden Unexpected Death Study

BACKGROUND

Earlier studies have reported both early morning and Monday peaks in occurrence of sudden cardiac arrest (SCA) in the community and appropriate defibrillator shocks in patients with an implantable cardioverter-defibrillator (ICD). However, a more recent analysis of ICD shocks reported absence of these peaks.

OBJECTIVE

The purpose of this study was to perform a contemporary evaluation of the circadian and septadian variation of SCA in the general population.

METHODS

The analysis was performed from an ongoing, population-based study of SCA in a Northwestern US community of approximately 1 million residents. To maximize accuracy, we focused on consecutive patients who presented with witnessed SCA and were attended by emergency medical services (EMS). The specific time of each SCA event was determined based on the time of the 911 call to EMS.

RESULTS

During 2002-2014, we identified 1535 patients age ≥18 years who suffered witnessed SCA, with time of first EMS contact recorded. There was no morning (6 AM to 12 PM) peak, and we observed a nadir in SCA events during 12 AM to 6 AM, with only 13.9% of events occurring during this 6-hour block (P <.0001). There was no peak on Mondays, but a nadir was observed on Sundays that accounted for only 11.3% of SCA events during the week (P = .004).

CONCLUSION

in this contemporary community-based study, we failed to observe the expected morning peak or the Monday peak in SCA, duplicating recent findings in primary prevention defibrillator patients. The significant public health implications of these findings merit further investigation.

CLOCK-BMAL1 regulate the cardiac L-type calcium channel subunit CACNA1C through PI3K-Akt signaling pathway

The heterodimerized transcription factors CLOCK-BMAL1 regulate the cardiomyocyte circadian rhythms. The L-type calcium currents play important role in the cardiac electrogenesis and arrhythmogenesis. Whether and how the CLOCK-BMAL1 regulate the cardiac L-type calcium channels are yet to be determined. The functions of the L-type calcium channels were evaluated with patch clamping techniques. Recombinant adenoviruses of CLOCK and BMAL1 were used in the expression experiments. We reported that the expressions and functions of CACNA1C (the α-subunit of the L-type calcium channels) showed circadian rhythms, with the peak at zeitgeber time 3 (ZT3). The endocardial action potential durations 90 (APD90) were correspondingly longer at ZT3. The protein levels of the phosphorylated Akt at threonine 308 (pAkt T308) also showed circadian rhythms. Overexpressions of CLOCK-BMAL1 significantly reduced the levels of CACNA1C while increasing the levels of pAkt T308 and pik3r1. Furthermore, the inhibitory effects of CLOCK-BMAL1 on CACNA1C could be abolished by the Akt inhibitor MK2206 or the PDK1 inhibitor GSK2334470. Collectively, our findings suggested that the expressions of the cardiac CACNA1C were under the CLOCK-BMAL1 regulation, probably through the PI3K-Akt signal pathway.

Frequency of Perceived Poststress Symptoms in Inpatients, Outpatients and Healthy Controls: The Role of Perceived Exhaustion and Stress

BACKGROUND

Poststress symptoms occur as a consequence of stress, most commonly during leisure periods such as weekends and vacations. However, the prevalence and the pathological mechanisms of poststress symptoms are poorly understood.

METHODS

Here, we compared the frequency of poststress symptoms in healthy controls (n = 984), outpatients (n = 420), and inpatients (n = 101). In outpatients, demographic factors, psychosocial stress, and perceived exhaustion were tested as predictors of poststress symptoms with multivariate regression analysis. Poststress symptoms and perceived exhaustion were assessed using 2 Neuropattern Questionnaires (the NPQ - Patient Questionnaire and the NPQ - Symptom List), and psychosocial stress was evaluated using the Patient Health Questionnaire (PHQ).

RESULTS

Poststress symptoms appeared in 2.9% of healthy controls, 20.0% of outpatients, and 34.7% of inpatients. Predictors were educational level, psychosocial stress, and perceived exhaustion. Poststress symptoms differed primarily between exhausted (75.0%) and nonexhausted patients (25.0%).

CONCLUSION

Poststress symptoms are rather common in clinical populations, and they are primarily associated with the degree of perceived exhaustion. Preliminary evidence suggests that poststress symptoms are possibly related to depletion of norepinephrine stores, which may facilitate a stratified preventive and therapeutic treatment of these subjects.

Acute Myocardial Infarction in Women: A Scientific Statement From the American Heart Association

Cardiovascular disease is the leading cause of mortality in American women. Since 1984, the annual cardiovascular disease mortality rate has remained greater for women than men; however, over the last decade, there have been marked reductions in cardiovascular disease mortality in women. The dramatic decline in mortality rates for women is attributed partly to an increase in awareness, a greater focus on women and cardiovascular disease risk, and the increased application of evidence-based treatments for established coronary heart disease. This is the first scientific statement from the American Heart Association on acute myocardial infarction in women. Sex-specific differences exist in the presentation, pathophysiological mechanisms, and outcomes in patients with acute myocardial infarction. This statement provides a comprehensive review of the current evidence of the clinical presentation, pathophysiology, treatment, and outcomes of women with acute myocardial infarction.

Circadian influences on myocardial infarction

Components of circadian rhythm maintenance, or "clock genes," are endogenous entrainable oscillations of about 24 h that regulate biological processes and are found in the suprachaismatic nucleus (SCN) and many peripheral tissues, including the heart. They are influenced by external cues, or Zeitgebers, such as light and heat, and can influence such diverse phenomena as cytokine expression immune cells, metabolic activity of cardiac myocytes, and vasodilator regulation by vascular endothelial cells. While it is known that the central master clock in the SCN synchronizes peripheral physiologic rhythms, the mechanisms by which the information is transmitted are complex and may include hormonal, metabolic, and neuronal inputs. Whether circadian patterns are causally related to the observed periodicity of events, or whether they are simply epi-phenomena is not well established, but a few studies suggest that the circadian effects likely are real in their impact on myocardial infarct incidence. Cycle disturbances may be harbingers of predisposition and subsequent response to acute and chronic cardiac injury, and identifying the complex interactions of circadian rhythms and myocardial infarction may provide insights into possible preventative and therapeutic strategies for susceptible populations.

Population-based incidence of sudden cardiac and unexpected death before and after the 2011 earthquake and tsunami in Iwate, northeast Japan

BACKGROUND

The aim of this study was to evaluate the temporal impact of the 2011 Japan earthquake and tsunami on the incidence of sudden cardiac and unexpected death (SCUD).

METHODS AND RESULTS

We surveyed the impact of the disaster on the incidence and clinical characteristics of SCUD in Iwate. To perform complete identification of SCUD for 8 weeks before and 40 weeks after the disaster, medical records and death certificates relevant to SCUD were surveyed in the study area. Compared with the previous year's rate, the incidence (per 10 000 person-year) of SCUD for the initial 4 weeks after the disaster (acute phase) was double (33.5 vs 18.9), and thereafter the rate returned to the previous level. Significant relationships were found between weekly numbers of SCUD and seismic activity (intensity, r=0.43; P<0.005: frequency, r=0.46; P<0.002). The standardized incidence ratio (SIR) of SCUD in the acute phase was significantly increased compared with that of previous years (1.71, 95% CI 1.33 to 2.16). Increased SIRs were predominantly found in female subjects (1.73, 95% CI 1.22 to 2.37), the elderly (1.73, 95% CI 1.29 to 2.27), and residents living in the tsunami-stricken area (1.83, 95% CI 1.33 to 2.46). In addition, SIRs for weekdays (1.71, 95% CI 1.28 to 2.24) and nights-mornings (2.09, 95% CI 1.48 to 2.86) were amplified.

CONCLUSIONS

The present results suggest that the magnitude of a disaster, related stress, and population aging may cause a temporary increase in the incidence of SCUD with amplification of ordinary weekly and circadian variations.

Temporal differences in out-of-hospital cardiac arrest incidence and survival

BACKGROUND

Understanding temporal differences in the incidence and outcomes of out-of-hospital cardiac arrest (OHCA) has important implications for developing preventative strategies and optimizing systems for OHCA care.

METHODS AND RESULTS

We studied 18 588 OHCAs of presumed cardiac origin in patients aged ≥18 years who received resuscitative efforts by emergency medical services (EMS) and were enrolled in the Cardiac Arrest Registry to Enhance Survival (CARES) from October 1, 2005, to December 31, 2010. We evaluated temporal variability in OHCA incidence and survival to hospital discharge. There was significant variability in the frequency of OHCA by hour of the day (P<0.001), day of the week (P<0.001), and month of the year (P<0.001), with the highest incidence occurring during the daytime, from Friday to Monday, in December. Survival to hospital discharge was lowest for OHCA that occurred overnight (from 11:01 pm to 7 am; 7.1%) versus daytime (7:01 am to 3 pm; 10.8%) or evening (3:01 pm to 11 pm; 11.3%; P<0.001) and during the winter (8.8%) versus spring (11.1%), summer (11.0%), or fall (10.0%; P<0.001). There was no difference in survival to hospital discharge between OHCAs that occurred on weekends and weekdays (9.5% versus 10.4%, P=0.06). After multivariable adjustment for age, sex, race, witness status, layperson resuscitation, first monitored cardiac rhythm, and emergency medical services response time, compared with daytime and spring, survival to hospital discharge remained lowest for OHCA that occurred overnight (odds ratio, 0.81; 95% confidence interval, 0.70-0.95; P=0.008) and during the winter (odds ratio, 0.81; 95% confidence interval, 0.70-0.94; P=0.006), respectively.

CONCLUSIONS

There is significant temporal variability in the incidence of and survival after OHCA. The relative contribution of patient pathophysiology, likelihood of the OHCA being observed, and prehospital and hospital-based resuscitative factors deserves further exploration.

Winter cardiovascular diseases phenomenon

This paper review seasonal patterns across twelve cardiovascular diseases: Deep venous thrombosis, pulmonary embolism, aortic dissection and rupture, stroke, intracerebral hemorrhage, hypertension, heart failure, angina pectoris, myocardial infarction, sudden cardiac death, venricular arrythmia and atrial fibrillation, and discuss a possible cause of the occurrence of these diseases. There is a clear seasonal trend of cardiovascular diseases, with the highest incidence occurring during the colder winter months, which have been described in many countries. This phenomenon likely contributes to the numbers of deaths occurring in winter. The implications of this finding are important for testing the relative importance of the proposed mechanisms. Understanding the influence of season and other factors is essential when seeking to implement effective public health measures.

A retrospective study of circadian and seasonal presentations of dogs with congestive heart failure: 119 cases (1997-2009)

OBJECTIVES

To test the hypothesis that there is a daily or seasonal rhythm in the presentation of congestive heart failure (CHF) in dogs.

DESIGN

Retrospective case series from 1997 to 2009.

SETTING

Small animal veterinary teaching hospital.

ANIMALS

One hundred and nineteen dogs with 126 acute presentations of CHF.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Medical records from a veterinary teaching hospital were searched for the occurrence of CHF. The effect of admission time, weekday, month, and season were analyzed separately using chi-square tests. CHF presentations were largely confined to Monday and Tuesday (57%) and between 9 am and 11:59 am (55%). CHF was more common during September, October, and November (37%).

CONCLUSIONS

Information from this study may assist veterinarians in educating clients about the timing of clinical signs, and enable veterinary hospitals to anticipate CHF cases during certain times of the day and year.

Increased risk of antipsychotic-related QT prolongation during nighttime: a 24-hour holter electrocardiogram recording study

Most antipsychotic agents can cause QT prolongation, which causes torsades de pointes. The QT interval in healthy subjects is longer during nighttime than during daytime. The QT interval of patients treated with antipsychotics may be prolonged during nighttime, and the effects of antipsychotics on the QT interval may differ between antipsychotics. This study investigated the circadian dynamics of the QT interval in patients treated with antipsychotics and healthy controls, using a 24-hour Holter electrocardiogram in a clinical setting. Sixty-six patients with a diagnosis of schizophrenia that were treated with risperidone or olanzapine and 40 healthy volunteers were enrolled. The QT intervals were corrected using the Fridericia formula (QTcF = QT / RR). Mean ± SD nighttime QTcFs were 411.6 ± 29.0, 395.9 ± 21.2, and 387.8 ± 19.0 milliseconds (ms) in the risperidone, olanzapine, and control groups, respectively. The mean daytime QTcFs were 397.7 ± 23.4, 392.4 ± 18.9, and 382.6 ± 17.3 ms, respectively. The mean nighttime QTcF of the risperidone group was significantly longer than that of the olanzapine and control groups, although there was no significant difference in the mean daytime QTcF between the risperidone and olanzapine groups. The current study used 24-hour Holter electrocardiograms to reveal significantly longer QT intervals in the risperidone group especially during nighttime. In clinical practices, evaluations of the QT interval have been conducted over short periods in the daytime, but it is believed that such methods may not be able to fully elucidate the effects of antipsychotics on the QT interval.

Vulnerability to paroxysmal oscillations in delayed neural networks: a basis for nocturnal frontal lobe epilepsy?

Resonance can occur in bistable dynamical systems due to the interplay between noise and delay (τ) in the absence of a periodic input. We investigate resonance in a two-neuron model with mutual time-delayed inhibitory feedback. For appropriate choices of the parameters and inputs three fixed-point attractors co-exist: two are stable and one is unstable. In the absence of noise, delay-induced transient oscillations (referred to herein as DITOs) arise whenever the initial function is tuned sufficiently close to the unstable fixed-point. In the presence of noisy perturbations, DITOs arise spontaneously. Since the correlation time for the stationary dynamics is ∼τ, we approximated a higher order Markov process by a three-state Markov chain model by rescaling time as t → 2sτ, identifying the states based on whether the sub-intervals were completely confined to one basin of attraction (the two stable attractors) or straddled the separatrix, and then determining the transition probability matrix empirically. The resultant Markov chain model captured the switching behaviors including the statistical properties of the DITOs. Our observations indicate that time-delayed and noisy bistable dynamical systems are prone to generate DITOs as switches between the two attractors occur. Bistable systems arise transiently in situations when one attractor is gradually replaced by another. This may explain, for example, why seizures in certain epileptic syndromes tend to occur as sleep stages change.

Sudden cardiac death: epidemiology, circadian variation, and triggers

Sudden cardiac death (SCD) remains a major health issue accounting for over 5% of annual mortality in the Western world. There are several causes of SCD, most commonly, coronary artery disease. Although identifying the prodrome of SCD has attracted considerable interest, a large proportion of patients die before any medical contact is established. SCD onset seems to follow a circadian pattern, most likely because of exposure to endogenous and exogenous triggers. The aim of the present report is to review the current knowledge of epidemiology, patterns of onset, and triggers of SCD and present directions for future research with a focus on coronary artery disease.

Temporal variation of out-of-hospital cardiac arrests in an equatorial climate

OBJECTIVE

We aimed to determine whether there is a seasonal variation of out-of-hospital cardiac arrests (OHCA) in an equatorial climate, which does not experience seasonal environmental change.

METHODS

We conducted an observational prospective study looking at the occurrence of OHCA in Singapore. Included were all patients with OHCA presented to Emergency Departments across the country. We examined the monthly, daily, and hourly number of cases over a three-year period. Data was analyzed using analysis of variance (ANOVA).

RESULTS

From October, 1st 2001 to October, 14th 2004, 2428 patients were enrolled in the study. Mean age for cardiac arrests was 60.6 years with 68.0% male. Ethnic distribution was 69.5% Chinese, 15.0% Malay, 11.0% Indian, and 4.4% Others. There was no significant seasonal variation (spring/summer/fall/winter) of events (ANOVA P = 0.71), monthly variation (P = 0.88) or yearly variation (P = 0.26). We did find weekly peaks on Mondays and a circadian pattern with daily peaks from 9-10 am.

CONCLUSIONS

We did not find any discernable seasonal pattern of cardiac arrests. This contrasts with findings from temperate countries and suggests a climatic influence on cardiac arrest occurrence. We also found that sudden cardiac arrests follow a circadian pattern.

Detection of subjects with higher self-reporting stress scores using heart rate variability patterns during the day

Heart rate variability (HRV) has been well established to measure instantaneous levels of mental stress. Circadian patterns of HRV features have been reported but their use to estimate levels of mental stress were not studied thoroughly. In this study, we investigated time dependent variations of HRV features to detect subjects under chronic mental stress. Sixty eight subjects were divided into high (n=10) and low stress group (n=43) depending on their self-reporting stress scores. HRV features were calculated during three different time periods of the day. High stress group showed decreased patterns of HRV features compared to low stress group. When logistic regression analysis was performed with raw multiple HRV features, the classification was 63.2% accurate. A new % deviance score reflecting the degree of difference from normal reference patterns increased the accuracy to 66.1%. Our data suggested that HRV patterns obtained at multiple time points of the day could provide useful data to monitor subjects under chronic stress.

Geographic-Time Distribution of Ambulance Calls in Singapore: Utility of Geographic Information System in Ambulance Deployment (CARE 3)

Introduction: Pre-hospital ambulance calls are not random events, but occur in patterns and trends that are related to movement patterns of people, as well as the geographical epidemiology of the population. This study describes the geographic-time epidemiology of ambulance calls in a large urban city and conducts a time demand analysis. This will facilitate a Systems Status Plan for the deployment of ambulances based on the most cost-effective deployment strategy. Materials and Methods: An observational prospective study looking at the geographic-time epidemiology of all ambulance calls in Singapore. Locations of ambulance calls were spot-mapped using Geographic Information Systems (GIS) technology. Ambulance response times were mapped and a demand analysis conducted by postal districts. Results: Between 1 January 2006 and 31 May 2006, 31,896 patients were enrolled into the study. Mean age of patients was 51.6 years (S.D. 23.0) with 60.0% male. Race distribution was 62.5% Chinese, 19.4% Malay, 12.9% Indian and 5.2% others. Trauma consisted 31.2% of calls and medical 68.8%. 9.7% of cases were priority 1 (most severe) and 70.1% priority 2 (moderate severity). Mean call receipt to arrival at scene was 8.0 min (S.D. 4.8). Call volumes in the day were almost twice those at night, with the most calls on Mondays. We found a definite geographical distribution pattern with heavier call volumes in the suburban town centres in the Eastern and Southern part of the country. We characterised the top 35 districts with the highest call volumes by time periods, which will form the basis for ambulance deployment plans. Conclusion: We found a definite geographical distribution pattern of ambulance calls. This study demonstrates the utility of GIS with despatch demand analysis and has implications for maximising the effectiveness of ambulance deployment. Keywords: Demand analysis, Despatch, Emergency Medical Services

Using demand analysis and system status management for predicting ED attendances and rostering

INTRODUCTION

It has been observed that emergency department (ED) attendances are not random events but rather have definite time patterns and trends that can be observed historically.

OBJECTIVES

To describe the time demand patterns at the ED and apply systems status management to tailor ED manpower demand.

METHODS

Observational study of all patients presenting to the ED at the Singapore General Hospital during a 3-year period was conducted. We also conducted a time series analysis to determine time norms regarding physician activity for various severities of patients.

RESULTS

The yearly ED attendances increased from 113387 (2004) to 120764 (2005) and to 125773 (2006). There was a progressive increase in severity of cases, with priority 1 (most severe) increasing from 6.7% (2004) to 9.1% (2006) and priority 2 from 33.7% (2004) to 35.1% (2006). We noticed a definite time demand pattern, with seasonal peaks in June, weekly peaks on Mondays, and daily peaks at 11 to 12 am. These patterns were consistent during the period of the study. We designed a demand-based rostering tool that matched doctor-unit-hours to patient arrivals and severity. We also noted seasonal peaks corresponding to public holidays.

CONCLUSION

We found definite and consistent patterns of patient demand and designed a rostering tool to match ED manpower demand.

The daily rhythm of heart attack morbidity and mortality may be influenced by the time of sunrise

A myocardialis infarctus morbiditásának, mortalitásának időpontja szezonális és napi ritmust is mutat, amely ingadozásra a napkelte és a napfényes órák száma is hatással lehet. A vizsgálat célja: Tanulmányozni kívánjuk, hogy a napkelte időpontja és a napfényes órák száma befolyásolja-e a szívinfarktus morbiditásának és mortalitásának szezonalitását, és hatással van-e diurnalis ritmusára. Módszer: Magyarországon retrospektív elemzést végeztünk 2004–2005-ben a klinikákra és a kórházi osztályokra felvett, akut szívinfarktuson átesett betegek ( n = 32329) és szívinfarktusban elhalálozottak ( n = 5142) vonatkozásában. Az Országos Egészségbiztosítási Pénztár adatbázisából a betegségek nemzetközi osztályozása szerint gyűjtöttük össze az adatokat. Eredmények: A napkelte és a myocardialis infarctus előfordulása és az utóbbi által okozott mortalitás között egyaránt pozitív korrelációt ( p < 0,01) találtunk szezonális és diurnalis ritmus vonatkozásában. A napfényes órák száma és a szívinfarktus szezonális előfordulása között negatív korrelációt ( r  = –0,107, p < 0,05) találtunk. A napfényes órák száma és az infarktus mortalitásának szezonális előfordulása között szintén negatív korrelációt ( r = –0,105, p < 0,05) tapasztaltunk. Következtetés: Adataink szerint a napkelte és a napfényes órák száma összefüggésbe hozható a szívinfarktus morbiditásának és mortalitásának gyakoriságával, de más tényezők is szerepet játszanak.

Sudden cardiac death in 13 captive chimpanzees (Pan troglodytes)

Sudden cardiac death (SCD), presumed secondary to fatal arrhythmias, is a common cause of mortality in captive chimpanzees at the Alamogordo Primate Facility. Over the 6-year period at the Alamogordo Primate Facility between 2001 and 2006, 13 animals were defined as sudden cardiac death (11 male and 2 female) on the basis of clinical presentation which was 38% of all deaths. All animals had annual physical exams, including electrocardiograms and serial blood pressures. Six of the 13 animals underwent a complete cardiac evaluation by a veterinary cardiologist and all six of these animals were diagnosed with various degrees of cardiomyopathy. Systemic hypertension was noted in two of the 13 cases and antemortem cardiac arrhythmias were seen in all 13 animals. Histological examination of the hearts revealed myocardial fibrosis in 12 chimpanzees. Most of the animals (10/13) that died of sudden cardiac death had cardiomegaly (increased heart weight/body weight ratio) and some degree of myocardial fibrosis noted. Additional data as well as serial diagnostic evaluations will be needed to identify the possible causes of sudden cardiac death in captive chimpanzees.

Detection of atrial fibrillation episodes using multiple heart rate variability features in different time periods

Circadian variations of cardiac diseases have been well known. For example, atrial fibrillation (AF) episodes show nocturnal predominance. In this study, we have developed multiple formulas that detect AF episodes in different times of the day. Heart rate variability features were calculated from randomly sampled three min ECG data. Logistic regression analyses were performed to generate three formulas for the entire day, daytime, and evening time. Compared to the first formula that disregarded the time of the day, the second formula for the daytime detection detected AF episodes more accurately (95.2% vs. 99.3%), whereas third formula for the evening time detection did less accurately (93.8%). These results suggest the detection of AF episodes might become more accurate by considering the time-dependent changes of HRV features. In addition, the detection method for the evening time requires further investigation.

Circadian, daily, and seasonal distributions of ventricular tachyarrhythmias in patients with implantable cardioverter-defibrillators

This study investigated the circadian, daily, and seasonal distributions of ventricular arrhythmias in patients with new implantable cardioverter-defibrillator placement at Creighton University Medical Center from January 2000 to December 2004. The incidence and distribution of ventricular tachyarrhythmias as recorded by implantable cardioverter-defibrillators were analyzed with respect to season, month, day of the week, and average daily temperature. Data from 154 consecutive patients (mean age 67 +/- 14 years; 78% men, 71% with ischemic heart disease [IHD], mean left ventricular ejection fraction 34 +/- 15%) were analyzed. During a mean follow-up of 35 +/- 19 months, a total of 1,055 episodes of spontaneously terminated ventricular tachycardia (VT) and 612 episodes of VT or ventricular fibrillation with appropriate device therapy occurred. Distributions in the incidence of VT and VT or ventricular fibrillation receiving appropriate therapy were similar in patients with IHD and non-IHD. Spontaneously terminated VT and appropriately treated VT or ventricular fibrillation episodes occurred with the greatest incidence in the winter months and the lowest incidence in summer, spring, and fall. A linear regression between the number of episodes and the average daily temperature showed a greater likelihood of the 2 events occurring on cooler days, irrespective of the cause of cardiac disease. A weekly distribution was also observed, with the greatest proportion of episodes occurring on Fridays and the lowest on Saturdays and Sundays. A bimodal circadian distribution was present, with the greatest peak occurring from 8 a.m. to 1 p.m. and a smaller peak occurring from 5 p.m. to 10 p.m. In conclusion, the occurrence of ventricular tachyarrhythmias appears to follow circadian, daily, and seasonal distributions that are similar in patients with IHD and non-IHD. The incidence inversely correlates with average daily temperatures.