Short-term exposure to ambient ozone associated with cardiac arrhythmias in healthy adults

Objective The exact biological mechanism whereby exposure to ambient ozone(O3)may contribute to clinical onset of cardiovascular events remains unclear.In this study,we aim to examine the impacts of O3 exposure on cardiac arrhythmias and potential pathways involved through autonomic dysfunction and myocardial injury.Methods Seventy-three non-smoking healthy adults were followed with 4 repeated measurements of 24-hour ambulatory arrhythmias,heart rate variability,ST-segment deviation,and blood pressure(BP)in Beijing,China,2014‒2016.Generalized additive mixed models coupled with distributed lag nonlinear models were constructed to evaluate the associations and potential interlinks between O3 exposure and outcome measurements.Results During the study period,24-hour average concentrations of ambient O3 were 47.4µg/m3(ranging from 1.0 to 165.9µg/m3).Increased risks of premature ventricular contraction and ventricular tachycardia were associated with interquartile range increases in O3 exposure during the last 5 days before each participant's clinic visit,with relative risks of 2.14(95%confidence interval[CI]:1.95 to 2.32)and 5.47(95%CI:3.51 to 7.43),respectively.Mediation analyses further showed that sympathetic activation,parasympathetic inhibition,and elevated BP levels,as well as heightened risks of ST-segment depression could mediate up to 47.74%of the risks of arrhythmias attributable to O3 exposure.Conclusion Our results suggest that short-term exposure to ambient O3 could prompt the genesis of arrhythmias partially through worsening autonomic function and myocardial burden.

Nonalcoholic Fatty Liver Disease (NAFLD) and Risk of Cardiac Arrhythmias: A New Aspect of the Liver-heart Axis

Nonalcoholic fatty liver disease (NAFLD) is a pathologic condition frequently observed in clinical practice.To date,the prevalence of NAFLD is approximately 25-30% among adults of the general population in Western countries but increases to approximately 70-75% among patients with type 2 diabetes mellitus.In the last decade,accumulating evidence has clearly demonstrated that patients with NAFLD have not only an increased liver-related morbidity and mortality but also an increased risk of fatal and non-fatal cardiovascular events.In particular,several studies have documented the existence of an independent association among NAFLD and cardiac changes in structure and function in both non-diabetic and diabetic patients.In addition,mounting evidence also suggests that there is a strong relationship between NAFLD and cardiac arrhythmias,such as atrial fibrillation,QTc prolongation and ventricular arrhythmias.This is of clinical interest,as it could explain,at least in part,the increased risk of death for cardiovascular disease in patients with NAFLD.Therefore,seeing that cardiovascular disease complications are the leading cause of disability and death in NAFLD patients,the recent European clinical practice guidelines advised to check the cardiovascular system in all patients with NAFLD.This clinical mini review will briefly describe the increasing body of evidence regarding the association between NAFLD and cardiac arrhythmias,and discuss the potential biological mechanisms underlying this association.

Automatic Classification of Cardiac Arrhythmias Based on Hybrid Features and Decision Tree Algorithm

Accurate classification of cardiac arrhythmias is a crucial task because of the non-stationary nature of electrocardiogram(ECG)signals.In a life-threatening situation,an automated system is necessary for early detection of beat abnormalities in order to reduce the mortality rate.In this paper,we propose an automatic classification system of ECG beats based on the multi-domain features derived from the ECG signals.The experimental study was evaluated on ECG signals obtained from the MIT-BIH Arrhythmia Database.The feature set comprises eight empirical mode decomposition(EMD)based features,three features from variational mode decomposition(VMD)and four features from RR intervals.In total,15 features are ranked according to a ranker search approach and then used as input to the support vector machine(SVM)and C4.5 decision tree classifiers for classifying six types of arrhythmia beats.The proposed method achieved best result in C4.5 decision tree classifier with an accuracy of 98.89%compared to cubic-SVM classifier which achieved an accuracy of 95.35%only.Besides accuracy measures,all other parameters such as sensitivity(Se),specificity(Sp)and precision rates of 95.68%,99.28%and 95.8%was achieved better in C4.5 classifier.Also the computational time of 0.65 s with an error rate of 0.11 was achieved which is very less compared to SVM.The multi-domain based features with decision tree classifier obtained the best results in classifying cardiac arrhythmias hence the system could be used efficiently in clinical practices.

Control of cardiac excitability and arrhythmias by microRNAs

Recent studies revealing the important roles of microRNAs（miRNAs） in regulating expression of ion channel genes have opened up a research field for extending and deepening our investi- gation into the cardiac excitability and the associated arrhythmogenesis.Cardiac excitability,the fundamental property of the cardiac myocytes,defines the cardiac conduction,repolarization,automaticity,intracellular calcium handling,and their regional heterogeneity. Our previous and ongoing studies and the work from other laboratories have demonstrated the significant involvement of miRNAs in regulating every aspects of cardiac excitability.We have found earlier that the muscle-specific miRNA miR-1 boosts up the arrhythmogenic potential through targeting gap junction channel connexin 43 in myocardial infarction.A subsequent study revealed that miR-1 can also cause arrhythmias by impairing Ca2+ handling by targeting phosphatase.We then identified another muscle-specific miRNA miR-133 promotes abnormal QT prolongation by repressing HERG K+ channel expression in diabetic cardiomyopathy. Subsequently,we discovered that both miR- 1 and miR-133 are involved in the reexpression of pacemaker channels HCN2/HCN4 to enhance abnormal automaticity in cardiac hypertrophy.Recently, we further identified miR-328 as an important determinant for atrial fibrillation（AF） and the associated adverse atrial electrical remodeling via targeting L-type Ca2+ channels.While all the above-mentioned miRNAs are proarrhythmic,we have newly identified for the first time a natural antiarrhythmic miRNA miR-26.We found that all three members of the miR-26 family is downregulated in their expression in AF tissues and this downregulation increases AF vulnerability as a result of removal of an endogenous antiarrhythmic factor.miR-26 downregulation shortens atrial action potential favoring AF by increasing inward rectifier K+ current（IK1） density. This is caused by an upregulation of Kir2.1 K+ channel subunit due to derepression of its encoding gene KCNJ2 as we have validated KCNJ2 as a target gene for miR-26.Administration of a LNA-modified antimiR-26 antisense through tail vein injection increases AF vulnerability as indicated by increased number of mice with AF induction by intracardiac pacing.And this effect is blunted by co-injection of either an adenovirus vector carrying miR-26 precursor sequence or a LNA-modified miR-26 mimic to specifically target KCNJ2.We further discovered that the activity of NFAT transcription factor is enhanced in AF which represses the transcription of miR-26. We characterized the promoter region of the host genes of all three members of the miR-26 miRNA family and identified a common cis-acting element for NFAT binding.Thus,our study unraveled a novel miRNA signaling pathway AF NFAT miR-26 KC-NJ2 /Kir2.1/IK1 AF as a positive feedback loop favoring AF and the remodeling process.

Dysglycemia and arrhythmias

Disorders in glucose metabolism can be divided into three separate but interrelated domains,namely hyperglycemia,hypoglycemia,and glycemic variability.Intensive glycemic control in patients with diabetes might increase the risk of hypoglycemic incidents and glucose fluctuations.These three dysglycemic states occur not only amongst patients with diabetes,but are frequently present in other clinical settings,such as during critically ill.A growing body of evidence has focused on the relationships between these dysglycemic domains with cardiac arrhythmias,including supraventricular arrhythmias(primarily atrial fibrillation),ventricular arrhythmias(malignant ventricular arrhythmias and QT interval prolongation),and bradyarrhythmias(bradycardia and heart block).Different mechanisms by which these dysglycemic states might provoke cardiac arrhythmias have been identified in experimental studies.A customized glycemic control strategy to minimize the risk of hyperglycemia,hypoglycemia and glucose variability is of the utmost importance in order to mitigate the risk of cardiac arrhythmias.

A CASE STUDIES SWALLOWING-INDUCED CARDIAC ARRHYTHMIA

ＧｕｏＹｉｎｇｃｈｕｎ（郭映春）；ＫａｎｇＪｉａｓｈｕｎ（康甲顺）；ＤｉｎｇＨｕｉｗｅｎ（丁会文）ＡＣＡＳＥＳＴＵＤＩＥＳＳＷＡＬＬＯＷＩＮＧ－ＩＮＤＵＣＥＤＣＡＲＤＩＡＣＡＲＲＨＹＴＨＭＩＡＧｕｏＹｉｎｇｃｈｕｎ；ＫａｎｇＪｉａｓｈｕｎ；ＤｉｎｇＨ...

Repeated atrial arrhythmia induced by cochineal red poisoning:A case report

BACKGROUND Cochineal red is an organic compound widely used in food,cosmetics,pharmaceuticals,textiles,and other fields due to its excellent safety profile.Poisoning caused by eating foods containing cochineal red is rare,and repeated atrial arrhythmia due to cochineal red poisoning is even rarer.CASE SUMMARY An 88-year-old Asian female patient was admitted to hospital due to a disturbance of consciousness.Twelve hours prior to presentation,the patient consumed 12 eggs containing cochineal red over a period of 2 h.At presentation,the patient was in a coma and had a score of 6 on the Glasgow Coma Scale(E2+VT+M4).The patient’s skin and mucous membranes were pink.Electrocardiography(ECG)revealed rapid atrial fibrillation without any signs of ischemia.We prescribed cedilan and fluid replacement for arrhythmia correction.Shortly after admission,the atrial fibrillation corrected to a normal sinus rhythm.On the day 2 of admission,the patient had a sudden atrial flutter accompanied by hemodynamic instability and rapidly declining arterial oxygen saturation between 85%and 90%.The sinus rhythm returned to normal after two electrical cardioversions.Six days after admission,the skin color of the patient returned to normal,and the ECG results were normal.The patient was transferred out of the intensive care unit and eventually discharged after 12 d in hospital.At the 2-mo follow-up visit,the patient was in good health with no recurrence of arrhythmia.CONCLUSION Although cochineal red is a safe,natural food additive,excessive consumption or occupational exposure can induce cardiac arrhythmias.

Transient ventricular arrhythmia as a rare cause of dizziness during exercise:A case report

BACKGROUND Dizziness is a common symptom in adults and usually due to peripheral causes affecting semicircular canal function or central causes affecting the pons,medulla,or cerebellum.Arrhythmia is a recognized cause of dizziness in people with structural or ischemic heart disease.We report a case of exercise-induced transient ventricular tachycardia and dizziness in a man with no evidence of organic heart disease.CASE SUMMARY A 42-year-old man presented with a 6 mo history of transient exercise-induced dizziness and prodromal palpitations.The patient was otherwise asymptomatic.Physical examination,otoscopy,vestibular tests,cerebellar tests,laboratory investigations,and imaging investigations were all unremarkable.Twenty-four hour Holter monitoring revealed four episodes of transient ventricular tachycardia during exercise.The patient was started on metoprolol and subsequently underwent radiofrequency catheter ablation.The patient reported a full recovery and no dizziness during daily activities.These results were maintained at the 6 mo follow-up.CONCLUSION Ventricular tachycardia is an uncommon but potentially serious cause of dizziness.The outcome of this case illustrates the benefits of careful clinical examination and communication with specialized centers.High clinical suspicion of arrhythmia in a patient with dizziness merits consultation with a cardiologist and referral to a specialized center to ensure timely diagnosis and treatment.

Brugada Syndrome: Anesthesia Management

Brugada’s Syndrome (BrS) is a rare but highly risky medical condition. It is a genetic disorder that may result in Ventricular Fibrillations (VF) that can lead to sudden cardiac arrest. The highest possible standards of safety in anesthetic medications must be followed and adequate measures must be taken with sufficient monitorization in patients with BrS. We wanted to mention the importance of monitorization in the early detection of possible complications and a careful follow-up even though no administration of anesthetic medication is present.

Self-Control of Heart Rhythmdisorders

The broken rhythm of the heart activity of a person can lead to fatal consequences if it is not detected at an early stage. The article described a device for counting and indicating the number of violations of rhythm of cardiac activity. The device is intended for home use and does not require medical knowledge. If the patient will notice a trend towards the increasing number of arrhythmias, he must seek for cardiology advice.

Cardiac arrhythmia with premature ventricular contractures induced by interferon beta in a patient with multiple sclerosis

Multiple sclerosis(MS)is an immune‑mediated inflammatory and neurodegenerative disease of the central nervous system.Interferon(IFN)beta is an active ingredient of five out of twelve disease modifying treatments approved for MS.We report a case of IFN‑beta‑induced cardiac arrhythmia with premature ventricular contractures in a patient recently diagnosed with MS.

Domain knowledge enhanced deep learning for electrocardiogram arrhythmia classification

Deep learning provides an effective way for automatic classification of cardiac arrhythmias,but in clinical decisionmaking,pure data-driven methods working as black-boxes may lead to unsatisfactory results.A promising solution is combining domain knowledge with deep learning.This paper develops a flexible and extensible framework for integrating domain knowledge with a deep neural network.The model consists of a deep neural network to capture the statistical pattern between input data and the ground-truth label,and a knowledge module to guarantee consistency with the domain knowledge.These two components are trained interactively to bring the best of both worlds.The experiments show that the domain knowledge is valuable in refining the neural network prediction and thus improves accuracy.

Cystic tumour of the atrioventricular node: case report and literature review

Cystic tumour of the atrioventricular node is the smallest tumour that can cause sudden cardiac death.This lesion arises from foregut endodermal rests which become enfolded into the heart during embryogenesis.Typically causing heart block,the tumour can cause sudden death despite pacemaker placement.Sudden death in such cases can be caused by arrhythmogenic ectopic foci arising from impaired electrical impulse propagation through the abnormal atrioventricular junction conducting tissue.

Efficacy on rabbits with arrhythmia: needling acupoint of Neiguan(PC6) at shallow or deep depth, and retaining needles for 10, 20, or 30 min

OBJECTIVE:To compare the effects of Neiguan(PC6)acupuncture at different depths and retention time on arrhythmia duration,myocardial tissue morphology,mRNA expression level of L-type calcium channelα1C subunit and Ca^(2+)-Mg^(2+)-At Pase activity in tachirrhythmia model of rabbits.METHODS:The tachyarrhythmia model was made by intravenous injection of barium chloride into the ears of rabbits.A total of 56 healthy adult male New Zealand big-eared white rabbits,apply the random number table method,divided into normal control group(group A),model group(group B),shallow needling Neiguan(PC6)10 min group(group C),shallow needling Neiguan(PC6)20 min group(group D),shallow needling Neiguan(PC6)30 min group(group E),deep needling Neiguan(PC6)10 min group(group F),deep needling Neiguan(PC6)20 min group(group G),deep needling Neiguan(PC6)30 min group(group H),7 animals in each group.Electrocardiograms were used to collect the duration of arrhythmia;hematoxylin-eosin staining method was performed on myocardial tissue,RT-PCR tested the expression ofα1C subunit mRNA,and the activity of Ca^(2+)-Mg^(2+)-ATPase were quantified by phosphorus determination method.RESULTS:The duration of arrhythmia in each acupuncture treatment group was shortened to varying degrees.Compare to the model group,the tissue damage from barium chloride inducing was improved in the acupuncture group.Compared to the model group,except for group E,most treatment groups had varying degrees of improvement with significantly down-regulated L-type calcium channelα1C subunit mRNA expressions level and increased Ca^(2+)-Mg^(2+)-ATPase activity.CONCLUSIONS:The effect of acupuncture at Neiguan(PC6)with different depths and retention time can reduce the duration of arrhythmia induced by barium chloride relatively,improve the induced pathological changes,down regulate L-type calcium channelα1C subunit mRNA expressions level and increase Ca^(2+)-Mg^(2+)-ATPase activity.Both the shallow and deep tissues of Neiguan(PC6)may be involved in transmitting acupuncture information.There is an optimal induction period for shallow needling at Neiguan(PC6)to reach the best therapeutic effect.