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https://www.readbyqxmd.com/read/28630170/characterization-of-aortic-valve-closure-artifact-during-outflow-tract-mapping-correlation-with-hemodynamics-and-mechanical-valves
#1
Jorge Romero, Olujimi Ajijola, Kalyanam Shivkumar, Roderick Tung
BACKGROUND: Premature ventricular contractions originating in the left ventricle outflow tract represent a significant subgroup of patients referred for catheter ablation. Mechanical artifacts from aortic valve leaflet motion may be observed during mapping, although the incidence and characteristics have not been reported. METHODS AND RESULTS: Twenty-eight consecutive patients with left ventricle outflow tract premature ventricular contraction were included. Electric signals recorded on the ablation catheter not coincident with atrial or ventricular depolarization were analyzed on the recording system...
June 2017: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/28623610/a-singular-role-of-ik1-promoting-the-development-of-cardiac-automaticity-during-cardiomyocyte-differentiation-by-ik1-induced-activation-of-pacemaker-current
#2
Yu Sun, Valeriy Timofeyev, Adrienne Dennis, Emre Bektik, Xiaoping Wan, Kenneth R Laurita, Isabelle Deschênes, Ronald A Li, Ji-Dong Fu
The inward rectifier potassium current (IK1) is generally thought to suppress cardiac automaticity by hyperpolarizing membrane potential (MP). We recently observed that IK1 could promote the spontaneously-firing automaticity induced by upregulation of pacemaker funny current (If) in adult ventricular cardiomyocytes (CMs). However, the intriguing ability of IK1 to activate If and thereby promote automaticity has not been explored. In this study, we combined mathematical and experimental assays and found that only IK1 and If, at a proper-ratio of densities, were sufficient to generate rhythmic MP-oscillations even in unexcitable cells (i...
June 16, 2017: Stem Cell Reviews
https://www.readbyqxmd.com/read/28620067/allele-specific-silencing-of-mutant-mrna-rescues-ultrastructural-and-arrhythmic-phenotype-in-mice-carriers-of-the-r4496c-mutation-in-the-ryanodine-receptor-gene-ryr2
#3
Rossana Bongianino, Marco Denegri, Andrea Mazzanti, Francesco Lodola, Alessandra Vollero, Simona Boncompagni, Silvia Fasciano, Giulia Rizzo, Damiano Mangione, Serena Barbaro, Alessia Di Fonso, Carlo Napolitano, Alberto Auricchio, Feliciano Protasi, Silvia G Priori
Rationale: Mutations in the cardiac Ryanodine Receptor gene (RYR2) cause dominant Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT), a leading cause of sudden death in apparently healthy individuals exposed to emotions or physical exercise. Objective: We investigated the efficacy of allele specific silencing by RNA interference to prevent CPVT phenotypical manifestations in our dominant CPVT mice model carriers of the heterozygous mutation R4496C in RYR2Methods and Results: We developed an in vitro mRNA and protein-based assays to screen multiple siRNAs for their ability to selectively silence mutant RYR2-R4496C mRNA over the corresponding wild-type (WT) allele...
June 15, 2017: Circulation Research
https://www.readbyqxmd.com/read/28610987/-tracking-interlead-heterogeneity-of-r-and-t-wave-morphology-to-disclose-latent-risk-for-sudden-cardiac-death
#4
Richard L Verrier, Heikki Huikuri
Sudden cardiac death (SCD) due primarily to ventricular fibrillation claims 1.5 million lives worldwide each year. In 45-50% of cases, it is the first manifestation of underlying heart disease. Traditional risk factors including smoking, hypertension, age, sex, as well as depressed left ventricular ejection fraction lack sufficient sensitivity and specificity to forewarn impending life-threatening arrhythmias. There has been a decades-long search for electrocardiographic (ECG) markers of SCD risk. Several interval-based indices such as QT dispersion and Tpeak-Tend interval held initial promise but ultimately yielded mixed results...
June 10, 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/28557338/coronary-sinus-lead-delay-index-for-optimization-of-coronary-sinus-lead-placement
#5
Mevlüt Koç, Onur Kaypakli, Gökhan Gözübüyük, Durmus Yıldıray Şahin
AIM: Optimization of coronary sinus (CS) lead position to the latest activated left ventricular (LV) area is important to increase cardiac resynchronization therapy (CRT) response. We aimed to detect the relationship between coronary sinus lead delay index (CSDI) and echocardiographic, electrocardiographic response to CRT treatment. METHODS: We prospectively included 137 consecutive patients with heart failure (HF) diagnosis, QRS ≥ 120 ms, left bundle branch block (LBBB), New York Heart Association score (NYHA) II-IV, LV ejection fraction (LVEF) <35% and scheduled for CRT (84 male, 53 female; mean age 65...
May 30, 2017: Annals of Noninvasive Electrocardiology
https://www.readbyqxmd.com/read/28549786/action-potential-based-mea-platform-for-in-vitro-screening-of-drug-induced-cardiotoxicity-using-human-ipscs-and-rat-neonatal-myocytes
#6
Danny Jans, Geert Callewaert, Olga Krylychkina, Luis Hoffman, Francesco Gullo, Dimiter Prodanov, Dries Braeken
Drug-induced cardiotoxicity poses a negative impact on public health and drug development. Cardiac safety pharmacology issues urged for the preclinical assessment of drug-induced ventricular arrhythmia leading to the design of several in vitro electrophysiological screening assays. In general, patch clamp systems allow for intracellular recordings, while multi-electrode array (MEA) technology detect extracellular activity. Here, we demonstrate a complementary metal oxide semiconductor (CMOS)-based MEA system as a reliable platform for non-invasive, long-term intracellular recording of cardiac action potentials at high resolution...
May 23, 2017: Journal of Pharmacological and Toxicological Methods
https://www.readbyqxmd.com/read/28543106/the-concept-of-triple-wavefront-fusion-during-biventricular-pacing-using-the-egm-to-produce-the-best-acute-hemodynamic-improvement-in-crt
#7
Iris A H Ter Horst, Margot D Bogaard, Anton E Tuinenburg, Thomas P Mast, Teun P de Boer, Pieter A F M Doevendans, Mathias Meine
BACKGROUND: Previous reports suggest that biventricular pacing (BiVp) fused with intrinsic conduction (BiVp-fusion, triple wavefront fusion) is associated with improved resynchronization compared to pure-BiVp in cardiac resynchronization therapy (CRT). This study aimed to assess the association between acute hemodynamic benefit of CRT and signs of BiVp-fusion by using a novel electrogram (EGM)-based method. METHODS: In 17 patients undergoing CRT implantation, 28 combinations of atrioventricular (AV) and interventricular (VV) delays were applied while invasively measuring acute hemodynamic response based on maximum rate of left ventricular (LV) pressure rise (LV dP/dtmax ) to assess optimal BiVp settings...
May 23, 2017: Pacing and Clinical Electrophysiology: PACE
https://www.readbyqxmd.com/read/28542320/the-ik1-kir2-1-channel-agonist-zacopride-prevents-and-cures-acute-ischemic-arrhythmias-in-the-rat
#8
Xu-Wen Zhai, Li Zhang, Yun-Fei Guo, Ying Yang, Dong-Ming Wang, Yan Zhang, Pan Li, Yi-Fan Niu, Qi-Long Feng, Bo-Wei Wu, Ji-Min Cao, Qing-Hua Liu
Arrhythmogenesis in acute myocardial infarction (MI) is associated with depolarization of resting membraine potential (RMP) and decrease of inward rectifier potassium current (IK1) in cardiomyocytes. However, clinical anti-arrhythmic agents that primarily act on RMP by enhancing the IK1 channel are not currently available. We hypothesized that zacopride, a selective and moderate agonist of the IK1/Kir2.1 channels, prevents and cures acute ischemic arrhythmias. To test this viewpoint, adult Sprague-Dawley (SD) rats were subjected to MI by ligating the left main coronary artery...
2017: PloS One
https://www.readbyqxmd.com/read/28541596/effects-of-ivabradine-and-beta-blocker-therapy-on-dobutamine-induced-ventricular-arrhythmias
#9
Kadir Uğur Mert, Gurbet Özge Mert, Bektas Morrad, Senan Tahmazov, Fezan Mutlu, Yüksel Cavusoglu
BACKGROUND: Indirect evidences suggest that the If blocker (ivabradine) may exert an antiarrhythmic effect in ventricular myocardium in heart failure patients by inhibiting spontaneous depolarizations but the clinical relevance of this mechanism is not known. Dobutamine (DOB) has been known to increase heart rate and the incidence of cardiac arrhythmias. In this study, we evaluated the effects of ivabradine on DOB-induced ventricular arrhythmias and compared it with that of β blocker therapy...
May 25, 2017: Kardiologia Polska
https://www.readbyqxmd.com/read/28509708/pvcs-pvc-induced-cardiomyopathy-and-the-role-of-catheter-ablation
#10
Esseim Sharma, Karuppiah Arunachalam, Mengyang Di, Antony Chu, Abhishek Maan
Premature ventricular contractions (PVCs) are common arrhythmias noticed in the clinical setting because of premature depolarization of the ventricular myocytes. Although often thought to be reflective of underlying disease rather than intrinsically harmful, PVCs have recently been linked with worse outcomes in patients without significant cardiac disease. Long-term exposure to a high PVC burden can lead to the development of PVC-induced cardiomyopathy. The pathogenesis of this condition is poorly understood at the current time...
June 2017: Critical Pathways in Cardiology
https://www.readbyqxmd.com/read/28507060/alogliptin-a-dipeptidyl-peptidase-4-inhibitor-alleviates-atrial-remodeling-and-improves-mitochondrial-function-and-biogenesis-in-diabetic-rabbits
#11
Xiaowei Zhang, Zhiwei Zhang, Yungang Zhao, Ning Jiang, Jiuchun Qiu, Yajuan Yang, Jian Li, Xue Liang, Xinghua Wang, Gary Tse, Guangping Li, Tong Liu
BACKGROUND: There is increasing evidence implicating atrial mitochondrial dysfunction in the pathogenesis of atrial fibrillation. In this study, we explored whether alogliptin, a dipeptidyl peptidase-4 inhibitor, can prevent mitochondrial dysfunction and atrial remodeling in a diabetic rabbit model. METHODS AND RESULTS: A total of 90 rabbits were randomized into 3 groups as follows: control group (n=30), alloxan-induced diabetes mellitus group (n=30), and alogliptin-treated (12...
May 15, 2017: Journal of the American Heart Association
https://www.readbyqxmd.com/read/28500173/tgf-%C3%AE-1-transforming-growth-factor-%C3%AE-1-plays-a-pivotal-role-in-cardiac-myofibroblast-arrhythmogenicity
#12
Nicolò Salvarani, Ange Maguy, Stefano A De Simone, Michele Miragoli, Florian Jousset, Stephan Rohr
BACKGROUND: TGF-β1 (transforming growth factor-β1) importantly contributes to cardiac fibrosis by controlling differentiation, migration, and collagen secretion of cardiac myofibroblasts. It is still elusive, however, to which extent TGF-β1 alters the electrophysiological phenotype of myofibroblasts and cardiomyocytes and whether it affects proarrhythmic myofibroblast-cardiomyocyte crosstalk observed in vitro. METHODS AND RESULTS: Patch-clamp recordings of cultured neonatal rat ventricular myofibroblasts revealed that TGF-β1, applied for 24 to 48 hours at clinically relevant concentrations (≤2...
May 2017: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/28484842/conventional-mapping-and-ablation-of-focal-ventricular-tachycardias-in-the-healthy-heart
#13
REVIEW
Sonia Busch, Johannes Brachmann, Ahmed Saleh, Mathias Forkmann
Ventricular tachycardias (VT) in the healthy heart, also known as idiopathic VTs, often have a focal origin. Triggered activity due to delayed after-depolarization is the most likely mechanism of focal VTs. Localization of the site of origin of focal VTs is based on activation mapping with or without combination with pace mapping. The characteristic anatomic site of origin of idiopathic VTs is the right and left outflow tract. Other sites include the tricuspid and mitral annulus, the papillary muscles, and Purkinje fibers...
May 8, 2017: Herzschrittmachertherapie & Elektrophysiologie
https://www.readbyqxmd.com/read/28484841/-bundle-branch-reentry-vt-diagnosis-mapping-and-ablation
#14
REVIEW
Christopher Reithmann
Macroreentry in the His-Purkinje system can result in sustained ventricular tachycardia (VT) termed bundle branch reentry VT. Bundle branch reentry is usually associated with His-Purkinje disease and depressed left ventricular function. In the case of typical bundle branch reentry, the right bundle is activated in the anterograde direction and ventricular depolarization begins at the distal end of the right bundle on the ventricular septum generating a typical left bundle branch block QRS morphology. However, atypical surface ECGs can also be found in patients with severe left ventricular dysfunction and involvement of the right ventricle complicating the diagnosis of bundle branch reentry VT...
May 8, 2017: Herzschrittmachertherapie & Elektrophysiologie
https://www.readbyqxmd.com/read/28468664/twenty-four-hour-ambulatory-electrocardiography-characterization-of-heart-rhythm-in-vipera-berus-envenomed-dogs
#15
Anna Rave Vestberg, Anna Tidholm, Ingrid Ljungvall
BACKGROUND: Vipera berus has a worldwide distribution and causes high morbidity in dogs annually. A complication to envenomation may be cardiac arrhythmias. The purpose of this study was to investigate the prevalence, types, and timing of arrhythmias, using 24-h ambulatory electrocardiography (24-AECG), in dogs bitten by V. berus in the first 24-32 h after envenomation. In addition, this study aimed to investigate if there were differences in selected clinical and hematological- and biochemical variables (including cardiac troponin I) at admission between V...
May 3, 2017: Acta Veterinaria Scandinavica
https://www.readbyqxmd.com/read/28458554/patient-characteristics-associated-with-false-arrhythmia-alarms-in-intensive-care
#16
Patricia R Harris, Jessica K Zègre-Hemsey, Daniel Schindler, Yong Bai, Michele M Pelter, Xiao Hu
INTRODUCTION: A high rate of false arrhythmia alarms in the intensive care unit (ICU) leads to alarm fatigue, the condition of desensitization and potentially inappropriate silencing of alarms due to frequent invalid and nonactionable alarms, often referred to as false alarms. OBJECTIVE: The aim of this study was to identify patient characteristics, such as gender, age, body mass index, and diagnosis associated with frequent false arrhythmia alarms in the ICU. METHODS: This descriptive, observational study prospectively enrolled patients who were consecutively admitted to one of five adult ICUs (77 beds) at an urban medical center over a period of 31 days in 2013...
2017: Therapeutics and Clinical Risk Management
https://www.readbyqxmd.com/read/28456609/computational-modeling-for-cardiac-safety-pharmacology-analysis-contribution-of-fibroblasts
#17
Xin Gao, Tylor Engel, Brian E Carlson, Tetsuro Wakatsuki
INTRODUCTION: Drug-induced proarrhythmic potential is an important regulatory criterion in safety pharmacology. The application of in silico approaches to predict proarrhythmic potential of new compounds is under consideration as part of future guidelines. Current approaches simulate electrophysiology of a single human adult ventricular cardiomyocyte. However, drug-induced proarrhythmic potential can be different when cardiomyocytes are surrounded by non-muscle cells. Incorporating fibroblasts in models of myocardium is important particularly for predicting a drugs cardiac liability in the aging population - a growing population who take more medications and exhibit increased cardiac fibrosis...
April 26, 2017: Journal of Pharmacological and Toxicological Methods
https://www.readbyqxmd.com/read/28444176/-j-waves-induced-after-short-coupling-intervals-a-manifestations-of-latent-depolarization-abnormality
#18
Yoshifusa Aizawa, Masafumi Nakayama, Masahito Sato, Masaaki Okabe, Yoshiyasu Aizawa, Seiji Takatsuki, Keiichi Fukuda
Aims: To confirm the presence of tachycardia-induced slur or notch in the terminal portion of the QRS complexes in a general patient population. Methods and results: A tachycardia-induced J wave was defined as a slur or notch in the terminal portion of the QRS complexes newly induced at short RR intervals during atrial premature contractions (APCs) or atrial electrical stimulation in the electrophysiological study (EPS). Twenty-three out of 2000 patients with general diseases were involved...
April 24, 2017: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
https://www.readbyqxmd.com/read/28396856/bidomain-predictions-of-virtual-electrode-induced-make-and-break-excitations-around-blood-vessels
#19
Adam J Connolly, Edward Vigmond, Martin J Bishop
INTRODUCTION AND BACKGROUND: Virtual electrodes formed by field stimulation during defibrillation of cardiac tissue play an important role in eliciting activations. It has been suggested that the coronary vasculature is an important source of virtual electrodes, especially during low-energy defibrillation. This work aims to further the understanding of how virtual electrodes from the coronary vasculature influence defibrillation outcomes. METHODS: Using the bidomain model, we investigated how field stimulation elicited activations from virtual electrodes around idealized intramural blood vessels...
2017: Frontiers in Bioengineering and Biotechnology
https://www.readbyqxmd.com/read/28395022/optogenetic-manipulation-of-anatomical-re-entry-by-light-guided-generation-of-a-reversible-local-conduction-block
#20
Masaya Watanabe, Iolanda Feola, Rupamanjari Majumder, Wanchana Jangsangthong, Alexander S Teplenin, Dirk L Ypey, Martin J Schalij, Katja Zeppenfeld, Antoine A F de Vries, Daniël A Pijnappels
Aims: Anatomical re-entry is an important mechanism of ventricular tachycardia, characterized by circular electrical propagation in a fixed pathway. It's current investigative and therapeutic approaches are non-biological, rather unspecific (drugs), traumatizing (electrical shocks), or irreversible (ablation). Optogenetics is a new biological technique that allows reversible modulation of electrical function with unmatched spatiotemporal precision using light-gated ion channels. We therefore investigated optogenetic manipulation of anatomical re-entry in ventricular cardiac tissue...
March 1, 2017: Cardiovascular Research
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