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https://www.readbyqxmd.com/read/28231318/effects-of-na-channel-blockers-on-the-restitution-of-refractory-period-conduction-time-and-excitation-wavelength-in-perfused-guinea-pig-heart
#1
Oleg E Osadchii
Na+ channel blockers flecainide and quinidine can increase propensity to ventricular tachyarrhythmia, whereas lidocaine and mexiletine are recognized as safe antiarrhythmics. Clinically, ventricular fibrillation is often precipitated by transient tachycardia that reduces action potential duration, suggesting that a critical shortening of the excitation wavelength (EW) may contribute to the arrhythmic substrate. This study examined whether different INa blockers can produce contrasting effects on the rate adaptation of the EW, which would explain the difference in their safety profile...
2017: PloS One
https://www.readbyqxmd.com/read/28229973/female-conspecifics-restore-rhythmic-singing-behaviour-in-arrhythmic-male-zebra-finches
#2
Neelu Anand Jha, Vinod Kumar
The present study investigated whether pairing with a conspecific female would restore rhythmicity in the singing behaviour of arrhythmic male songbirds. We recorded the singing and, as the circadian response indicator, monitored the activity-rest pattern in male zebra finches (Taeniopygia guttata) housed without or with a conspecific female under 12 h light: 12 h darkness (12L:12D) or constant bright light (LL bright). Both unpaired and paired birds exhibited a significant daily rhythm in the singing and activity behaviour, but paired birds, under 12L:12D, showed a ~2 h extension in the evening...
March 2017: Journal of Biosciences
https://www.readbyqxmd.com/read/28229272/prophylactic-implantable-cardioverter-defibrillator-in-heart-failure-the-growing-evidence-for-all-or-primum-non-nocere-for-some
#3
REVIEW
Khang-Li Looi, Nigel Lever, Anthony Tang, Sharad Agarwal
Heart failure (HF) is a common health problem and has reached epidemic in many western countries. Despite the current era of HF treatment, the risk of sudden cardiac death (SCD) in HF remains significant. Implantable cardioverter defibrillator (ICD) support has been shown to reduce the risk of SCD in patients with HF and impaired left ventricular function. Prophylactic ICD implantation in HF patients seems a logical step to reduce mortality through a reduction in SCD. However, ICD implantation is an invasive procedure, and both short- and long-term complications can occur...
February 23, 2017: Heart Failure Reviews
https://www.readbyqxmd.com/read/28227934/effect-of-embedding-dimension-on-complexity-measures-in-identifying-arrhythmia
#4
Radhagayathri K Udhayakumar, Chandan Karmakar, Peng Li, Marimuthu Palaniswami, Radhagayathri K Udhayakumar, Chandan Karmakar, Peng Li, Marimuthu Palaniswami, Marimuthu Palaniswami, Radhagayathri K U Udhayakumar, Peng Li, Chandan Karmakar
Entropy measures like Approximate entropy (ApEn) and Sample entropy (SampEn) are well established tools to analyze Heart Rate Variability (HRV) data. Critical parameters involved in these computations namely embedding dimension m and tolerance r are in most cases assumed to be 2 and 0.2*signal SD (standard devaition) respectively. Such assumptions do not work fairly across data sets and thus create misleading results in many cases. Problems with r have been addressed with the advent of newer entropy measures like Permutation entropy (PE), Fuzzy entropy (FuzzyEn) and Distribution entropy (DistEn) that simply eliminate, modify or replace r from calculations...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227376/electrocardiogram-reconstruction-from-high-resolution-voltage-optical-mapping
#5
Ilija Uzelac, Conner Herndon, James Farmer, Flavio Fenton, Ilija Uzelac, Conner Herndon, James Farmer, Flavio Fenton, Ilija Uzelac, Conner Herndon, James Farmer, Flavio Fenton
Electrocardiogram recordings during opucal mapping experiments in heart tissue are commonly used tu monitor the health of the preparation and to obtain dominant frequencies during arrhythmic and defibrillatory studies. However the use of ECG reconstructed from optical mapping is seldom used and to date it has not been strictly validated. In this manuscript we present the first detailed validation and comparison of Optical Mapping ECG, or OM-ECG, with standard ECG recordings by calculating the electrostatic potential in space as a function of the voltage measured optically and describe the different approximations that can be used to obtain unipolar or bipolar ECG recordings...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28226552/patient-specific-detection-of-ventricular-tachycardia-in-remote-continuous-health-devices
#6
Amit Juneja, Michael Marefat, Amit Juneja, Michael Marefat, Amit Juneja, Michael Marefat
Ventricular Tachycardia (VT) is a dangerous arrhythmic event which can lead to sudden cardiac death if not detected and taken care of in time. This work uses non-linear features derived from Recurrence Quantification Analysis (RQA) along with Kolmogorov complexity, by analyzing the ECG signals, to train a classifier which can predict VT prior to their onset in remote continuous health devices. Compressed ECG signal along with amplitude ranges extracted from the ECG signal are used as features to strengthen the classifier...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28226460/pro-arrhythmic-effect-of-heart-rate-variability-during-periodic-pacing
#7
Kanchan Kulkarni, Steven W Lee, Elena G Tolkacheva, Kanchan Kulkarni, Steven W Lee, Elena G Tolkacheva, Elena G Tolkacheva, Steven W Lee, Kanchan Kulkarni
Clinically, healthy hearts have been associated with a high ventricular heart rate variability (HRV) while diseased hearts have been known to exhibit low ventricular HRV. Hence, low HRV is suggested to be a marker of cardiac ventricular arrhythmias. Over the past few years, there has been considerable amount of interest in incorporating HRV in pacing to emulate healthy heart conditions and re-stabilize the electrical activity in diseased hearts. Recently, we used single cell numerical simulations to demonstrate that HRV incorporated into periodic pacing promotes alternans formation and thus, can be pro-arrhythmic...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28223225/the-control-of-cardiac-ventricular-excitability-by-autonomic-pathways
#8
REVIEW
Malcolm Finlay, Stephen C Harmer, Andrew Tinker
Central to the genesis of ventricular cardiac arrhythmia are variations in determinants of excitability. These involve individual ionic channels and transporters in cardiac myocytes but also tissue factors such as variable conduction of the excitation wave, fibrosis and source-sink mismatch. It is also known that in certain diseases and particularly the channelopathies critical events occur with specific stressors. For example, in hereditary long QT syndrome due to mutations in KCNQ1 arrhythmic episodes are provoked by exercise and in particular swimming...
February 13, 2017: Pharmacology & Therapeutics
https://www.readbyqxmd.com/read/28223004/sudden-cardiac-death-among-hemodialysis-patients
#9
Melissa S Makar, Patrick H Pun
Hemodialysis patients carry a large burden of cardiovascular disease; most onerous is the high risk for sudden cardiac death. Defining sudden cardiac death among hemodialysis patients and understanding its pathogenesis are challenging, but inferences from the existing literature reveal differences between sudden cardiac death among hemodialysis patients and the general population. Vascular calcifications and left ventricular hypertrophy may play a role in the pathophysiology of sudden cardiac death, whereas traditional cardiovascular risk factors seem to have a more muted effect...
February 17, 2017: American Journal of Kidney Diseases: the Official Journal of the National Kidney Foundation
https://www.readbyqxmd.com/read/28219898/sk4-k-channels-are-therapeutic-targets-for-the-treatment-of-cardiac-arrhythmias
#10
Shiraz Haron-Khun, David Weisbrod, Hanna Bueno, Dor Yadin, Joachim Behar, Asher Peretz, Ofer Binah, Edith Hochhauser, Michael Eldar, Yael Yaniv, Michael Arad, Bernard Attali
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a stress-provoked ventricular arrhythmia, which also manifests sinoatrial node (SAN) dysfunction. We recently showed that SK4 calcium-activated potassium channels are important for automaticity of cardiomyocytes derived from human embryonic stem cells. Here SK4 channels were identified in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) from healthy and CPVT2 patients bearing a mutation in calsequestrin 2 (CASQ2-D307H) and in SAN cells from WT and CASQ2-D307H knock-in (KI) mice...
February 20, 2017: EMBO Molecular Medicine
https://www.readbyqxmd.com/read/28219794/atrial-fibrillation-in-hypertrophic-cardiomyopathy-a-turning-point-towards-increased-morbidity-and-mortality
#11
Thomas Zegkos, Georgios K Efthimiadis, Despoina G Parcharidou, Thomas D Gossios, Georgios Giannakoulas, Dimitris Ntelios, Antonis Ziakas, Stelios Paraskevaidis, Haralambos I Karvounis
BACKGROUND: Atrial fibrillation (AF) is the most common arrhythmic event in patients with hypertrophic cardiomyopathy (HCM). The aim of this study was to identify the clinical and the prognostic impact of the arrhythmia on a large cohort of patients with HCM. METHODS: The echocardiographic and clinical correlates, the predictors of AF and thromboembolic stroke and the prognostic significance of the arrhythmia were evaluated in 509 patients with an established diagnosis of HCM...
February 17, 2017: Hellenic Journal of Cardiology: HJC, Hellēnikē Kardiologikē Epitheōrēsē
https://www.readbyqxmd.com/read/28217939/pitx2-dependent-gene-regulation-in-atrial-fibrillation-and-rhythm-control
#12
Fahima Syeda, Paulus Kirchhof, Larissa Fabritz
Atrial fibrillation (AF) is a common arrhythmia. Better prevention and treatment of AF are needed to reduce AF-associated morbidity and mortality. There are several major mechanisms that cause AF in patients, including a genetic predisposition to develop AF. Genome-wide association studies (GWAS) have identified genetic variants associated with AF populations, with the strongest hits clustering on chromosome 4q25, close to the gene for the homeobox transcription factor PITX2. The effect of these common gene variants on cardiac PITX2 mRNA is currently under study...
February 19, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28217224/mortality-and-predictors-of-appropriate-implantable-cardioverter-defibrillator-therapy-in-japanese-patients-with-multicenter-automatic-defibrillator-implantation-trial-ii-criteria
#13
Yoshimori An, Kenji Ando, Yoshimitsu Soga, Akihiro Nomura, Michio Nagashima, Kentaro Hayashi, Yu Makihara, Masato Fukunaga, Ken-Ichi Hiroshima, Masakiyo Nobuyoshi, Masahiko Goya
BACKGROUND: Data regarding long-term mortality and factors influencing appropriate therapies in Japanese patients with implantable cardioverter defibrillators (ICD), who satisfy the Multicenter Automatic Defibrillator Implantation Trial II (MADIT II) criteria for primary prevention, remain scarce. METHODS: A total of 118 consecutive patients who underwent ICD implantation without any prior ventricular arrhythmic event, from January 2000 to December 2012, were enrolled based on the MADIT II criteria: left ventricular ejection fraction (LVEF) of ≤30% with ischemic heart disease and at least 4 weeks after a myocardial infarction...
February 2017: Journal of Arrhythmia
https://www.readbyqxmd.com/read/28215569/cardiac-phenotype-and-long-term-prognosis-of-arrhythmogenic-right-ventricular-cardiomyopathy-dysplasia-patients-with-late-presentation
#14
Aditya Bhonsale, Anneline S J M Te Riele, Abhishek C Sawant, Judith A Groeneweg, Cynthia A James, Brittney Murray, Crystal Tichnell, Thomas P Mast, Michelle J van der Pols, Maarten J M Cramer, Dennis Dooijes, Jeroen F van der Heijden, Harikrishna Tandri, J Peter van Tintelen, Daniel P Judge, Richard N W Hauer, Hugh Calkins
BACKGROUND: The clinical profile of Arrhythmogenic Right Ventricular Cardiomyopathy/ Dysplasia patients with late presentation (ARVC/D) is unknown. OBJECTIVE: To characterize the genotype, cardiac phenotype and long term outcomes of ARVC/D patients with late presentation (age≥ 50 years at diagnosis) METHODS: 502 patients with ARVC/D diagnosis from Johns Hopkins and Utrecht registries were studied and long term clinical outcomes ascertained. RESULTS: Late presentation was seen in 104 (21%) patients (38% PKP2 carriers) with 3% ≥ 65 years at diagnosis...
February 12, 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/28213374/diurnal-differences-in-risk-of-cardiac-arrhythmias-during-spontaneous-hypoglycemia-in-young-people-with-type-1-diabetes
#15
Peter Novodvorsky, Alan Bernjak, Elaine Chow, Ahmed Iqbal, Lianne Sellors, Scott Williams, Robert A Fawdry, Bhavin Parekh, Richard M Jacques, Jefferson L B Marques, Paul J Sheridan, Simon R Heller
OBJECTIVE: Hypoglycemia may exert proarrhythmogenic effects on the heart via sympathoadrenal stimulation and hypokalemia. Hypoglycemia-induced cardiac dysrhythmias are linked to the "dead-in-bed syndrome," a rare, but devastating, condition. We examined the effect of nocturnal and daytime clinical hypoglycemia on electrocardiogram (ECG) in young people with type 1 diabetes. RESEARCH DESIGN AND METHODS: Thirty-seven individuals with type 1 diabetes underwent 96 h of simultaneous ambulatory ECG and blinded continuous interstitial glucose monitoring (CGM) while symptomatic hypoglycemia was recorded...
February 17, 2017: Diabetes Care
https://www.readbyqxmd.com/read/28209216/hypertrophic-cardiomyopathy-with-left%C3%A2-ventricular-apical-aneurysm-implications-for-risk-stratification-and-management
#16
Ethan J Rowin, Barry J Maron, Tammy S Haas, Ross F Garberich, Weijia Wang, Mark S Link, Martin S Maron
BACKGROUND: A previously under-recognized subset of hypertrophic cardiomyopathy (HCM) patients with left ventricular (LV) apical aneurysms is being identified with increasing frequency. However, risks associated with this subgroup are unknown. OBJECTIVES: The authors aimed to clarify clinical course and prognosis of a large cohort of HCM patients with LV apical aneurysms over long-term follow-up. METHODS: The authors retrospectively analyzed 1,940 consecutive HCM patients at 2 centers, 93 of which (4...
February 21, 2017: Journal of the American College of Cardiology
https://www.readbyqxmd.com/read/28192183/measuring-kinetics-and-potency-of-herg-block-for-cipa
#17
Monique J Windley, Najah Abi-Gerges, Bernard Fermini, Jules C Hancox, Jamie I Vandenberg, Adam P Hill
INTRODUCTION: The Comprehensive in vitro Proarrhythmic Assay (CiPA) aims to update current cardiac safety testing to better evaluate arrhythmic risk. A central theme of CiPA is the use of in silico approaches to risk prediction incorporating models of drug binding to hERG. To parameterize these models, accurate in vitro measurement of potency and kinetics of block is required. The Ion Channel Working Group was tasked with: i) selecting a protocol that could measure kinetics of block and was easily implementable on automated platforms for future rollout in industry and ii) acquiring a reference dataset using the standardized protocol...
February 10, 2017: Journal of Pharmacological and Toxicological Methods
https://www.readbyqxmd.com/read/28191886/sirtuin-1-regulates-cardiac-electrical-activity-by-deacetylating-the-cardiac-sodium-channel
#18
Ajit Vikram, Christopher M Lewarchik, Jin-Young Yoon, Asma Naqvi, Santosh Kumar, Gina M Morgan, Julia S Jacobs, Qiuxia Li, Young-Rae Kim, Modar Kassan, Jing Liu, Mohanad Gabani, Ajay Kumar, Haider Mehdi, Xiaodong Zhu, Xiaoqun Guan, William Kutschke, Xiaoming Zhang, Ryan L Boudreau, Shengchuan Dai, Daniel S Matasic, Saet-Byel Jung, Kenneth B Margulies, Vikas Kumar, Markus M Bachschmid, Barry London, Kaikobad Irani
The voltage-gated cardiac Na(+) channel (Nav1.5), encoded by the SCN5A gene, conducts the inward depolarizing cardiac Na(+) current (INa) and is vital for normal cardiac electrical activity. Inherited loss-of-function mutations in SCN5A lead to defects in the generation and conduction of the cardiac electrical impulse and are associated with various arrhythmia phenotypes. Here we show that sirtuin 1 deacetylase (Sirt1) deacetylates Nav1.5 at lysine 1479 (K1479) and stimulates INa via lysine-deacetylation-mediated trafficking of Nav1...
February 13, 2017: Nature Medicine
https://www.readbyqxmd.com/read/28188930/microrna-135a-regulates-sodium-calcium-exchanger-gene-expression-and-cardiac-electrical-activity
#19
Eric Duong, Jiening Xiao, Xiao Yan Qi, Stanley Nattel
BACKGROUND: Complete atrioventricular block (CAVB) causes arrhythmogenic remodeling and increases the risk of Torsades de Pointes (TdP) arrhythmias. MicroRNAs (miRNAs) are key regulators of gene-expression that contribute to cardiac remodeling. OBJECTIVE: To assess miRNA changes after complete atrioventricular block (CAVB) and identify novel candidates potentially involved in arrhythmogenic cardiac remodeling. METHODS: CAVB was induced in mice via His bundle ablation...
February 7, 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/28188473/outpatient-treatment-with-the-wearable-cardioverter-defibrillator-clinical-experience-in-two-dutch-centres
#20
A F B E Quast, V F van Dijk, A A M Wilde, R E Knops, L V A Boersma
INTRODUCTION: The latest European Society of Cardiology Guidelines recommend consideration of a wearable cardioverter-defibrillator (WCD) for patients with a poor left ventricular ejection fraction (LVEF) who are at risk of sudden arrhythmic death but are not eligible for an implantable defibrillator. For these patients a WCD can be an alternative to long-term hospitalisation. PURPOSE: To evaluate the use of WCD therapy in these patient groups in two Dutch centres...
February 10, 2017: Netherlands Heart Journal
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