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Weiting Huang, Paul Chun Yih Lim, Chi-Keong Ching
A Mobitz type I block (Wenckebach phenomenon) with narrow QRS complex is almost always due to a lesion in the AV node. In a type I block with wide QRS complex (>0.12sec), the block can be in the His-Purkinje system in 60-70% of the cases. Even though the progressive PR prolongation with every conducted beat suggests Wenckebach phenomenon, one needs to pay attention to the accompanying QRS complex. In the setting of persistent right bundle branch block, axis change of subsequent conducted beat before an unconducted p suggests alternating fascicular block, giving clue to unreliable infra-Hisian conduction; and in the setting of symptoms, a pacemaker should be implanted...
March 2017: Journal of Electrocardiology
Alicja Cepiel, Agnieszka Noszczyk-Nowak, Robert Pasławski, Adrian Janiszewski, Urszula Pasławska
BACKGROUND: Invasive electrophysiology study (EPS) is one of the most important adjunct tests for the evaluation of arrhythmias in human medicine. Moreover, it is a vital procedure conducted prior to, and after, radiofrequency ablation. However, EPS is neither well known, nor widely used in veterinary medicine. OBJECTIVE: To define the values for intracardiac conduction parameters determined during invasive EPS in dogs. ANIMALS AND METHODS: The study included 16 admitted dogs of various breeds, sex and ages and 6 control Beagles...
March 21, 2017: Veterinary Quarterly
W Th Wenckebach
Dynamic Nuclear Polarization (DNP) via the mechanism of thermal mixing has proven itself most powerful for the orientation of nuclear spins in polarized targets and hyperpolarization for magnetic resonance imaging (MRI). Unfortunately, theoretical descriptions of this mechanism have been limited to using-at least partially-the high temperature approximation, in which Boltzmann factors are expanded linearly. However, the high nuclear spin polarization required and obtained for these applications does not justify such approximations...
February 20, 2017: Journal of Magnetic Resonance
Esteban W Rivarola, Denise Hachul, Tan Wu, Cristiano Pisani, Carina Hardy, Fabrizio Raimundi, Sissy Melo, Francisco Darrieux, Mauricio Scanavacca
BACKGROUND: Autonomic denervation is an alternative approach for patients with symptomatic bradycardia. No consensus exists on the critical targets and end points of the procedure. The aim of this study was to identify immediate end points and critical atrial regions responsible for vagal denervation. METHODS AND RESULTS: We enrolled 14 patients (50% men; age: 34.0±13.8 years) with cardioinhibitory syncope, advanced atrioventricular block or sinus arrest, and no structural heart disease...
February 2017: Circulation. Arrhythmia and Electrophysiology
Agnieszka Noszczyk-Nowak, Alicja Cepiel, Adrian Janiszewski, Robert Pasławski, Jacek Gajek, Urszula Pasławska, Józef Nicpoń
BACKGROUND: Swine are a well-recognized animal model for human cardiovascular diseases. Despite the widespread use of porcine model in experimental electrophysiology, still no reference values for intracardiac electrical activity and conduction parameters determined during an invasive electrophysiology study (EPS) have been developed in this species thus far. OBJECTIVES: The aim of the study was to develop a set of normal values for intracardiac electrical activity and conduction parameters determined during an invasive EPS of swine...
November 2016: Advances in Clinical and Experimental Medicine: Official Organ Wroclaw Medical University
Mario Matta, Matteo Anselmino, Marco Scaglione, Marco Vitolo, Federico Ferraris, Paolo Di Donna, Domenico Caponi, Davide Castagno, Fiorenzo Gaita
PURPOSE: Catheter ablation of the slow pathway is the most effective treatment for atrioventricular nodal reentrant tachycardia (AVNRT). Cryoenergy, compared to radiofrequency, relates to lower heart block risk but higher incidence of AVNRT recurrences. The aims of this study are to confirm the safety and efficacy of AVNRT cryoablation and to identify predictors of long-term recurrences. METHODS: Among 241 patients undergoing AVNRT cryoablation, 239 (99.2%) experienced acute effective cryoablation of the slow pathway, and no procedure-related complications were reported...
December 10, 2016: Journal of Interventional Cardiac Electrophysiology: An International Journal of Arrhythmias and Pacing
Ujjwal Rastogi, Nidhi Kumars
Lyme disease is a multisystem disorder affecting dermatologic, cardiac, nervous and musculoskeletal systems. Cardiac manifestations occur in about 5% of Lyme infections and stem from the involvement of the cardiac conduction system, resulting in varying degrees of sino-atrioventricular block. Occasionally, Lyme infection may also present with myopericarditis. Unlike isolated conduction node disease, myocardial involvement presents a great diagnostic and therapeutic dilemma for the physician. We report the case of a 68 year-old male cardiologist who presented with new onset exertional dyspnea and palpitations...
February 2016: Journal of Atrial Fibrillation
Hiroyuki Takaoka, Nobusada Funabashi, Koya Ozawa, Masae Uehara, Marehiko Ueda, Takuro Horikoshi, Takashi Uno, Yoshio Kobayashi
PURPOSE: To evaluate CT utility for detection of cardiac or lung abnormalities in the diagnosis of organic cardiac disease in subjects with second- or third-degree atrioventricular block (AVB) excepting Wenckebach type. MATERIALS AND METHODS: A total of 50 consecutive patients (25 male; 64±15years) with de novo third- or second-degree AVB underwent both TTE and a combination of cardiac and chest 320 slice CT (Aquilion one, Toshiba Medical) and were retrospectively analyzed...
February 1, 2017: International Journal of Cardiology
Heidi L Lujan, Joshua P Rivers, Stephen E DiCarlo
Mice may now be the preferred animal model for biomedical research due to its anatomical, physiological, and genetic similarity to humans. However, little is known about accentuated antagonism of chronotropic and dromotropic properties in conscious mice. Accordingly, we describe the complex and interacting influence of the autonomic nervous system on cardiac electrophysiology in conscious mice. Specifically, we report the effects of single and combined cardiac autonomic blockade on measurements of pulse interval (heart rate), atrio-ventricular interval, sinus node recovery time (SNRT), SNRT corrected for spontaneous sinus cycle, and Wenckebach cycle length in conscious mice free of the confounding influences of anesthetics and surgical trauma...
December 2016: Autonomic Neuroscience: Basic & Clinical
Takaaki Kamatani, Ayako Akizuki, Seiji Kondo, Tatsuo Shirota
Although cardiac arrhythmias are occasionally associated with dental extractions and dental anesthesia, atrioventricular block is rarely seen during dental procedures. We report a rare case of type I second-degree atrioventricular block (Wenckebach phenomenon) occurring after bilateral extraction of impacted mandibular third molars under general anesthesia in a 16-year-old Japanese girl. Under consultation with a cardiovascular physician, we carefully monitored the patient's vital signs postoperatively, including blood pressure, oxygen saturation, and electrocardiogram, using a bedside monitor...
2016: Anesthesia Progress
Nele Vandersickel, Arne Defauw, Peter Dawyndt, Alexander V Panfilov
The main mechanism of formation of reentrant cardiac arrhythmias is via formation of waveblocks at heterogeneities of cardiac tissue. We report that heterogeneity and the area of waveblock can extend itself in space and can result formation of new additional sources, or termination of existing sources of arrhythmias. This effect is based on a new form of instability, which we coin as global alternans instability (GAI). GAI is closely related to the so-called (discordant) alternans instability, however its onset is determined by the global properties of the APD-restitution curve and not by its slope...
2016: Scientific Reports
Mark A Skarsfeldt, Helena Carstensen, Lasse Skibsbye, Chuyi Tang, Rikke Buhl, Bo H Bentzen, Thomas Jespersen
The inwardly rectifying potassium current (IK 1) conducted through Kir2.X channels contribute to repolarization of the cardiac action potential and to stabilization of the resting membrane potential in cardiomyocytes. Our aim was to investigate the effect of the recently discovered IK 1 inhibitor PA-6 on action potential repolarization and refractoriness in isolated rat hearts. Transiently transfected HEK-293 cells expressing IK 1 were voltage-clamped with ramp protocols. Langendorff-perfused heart experiments were performed on male Sprague-Dawley rats, effective refractory period, Wenckebach cycle length, and ventricular effective refractory period were determined following 200 nmol/L PA-6 perfusion...
April 2016: Physiological Reports
Akinori Sairaku, Yukiko Nakano, Kazuyoshi Suenari, Takehito Tokuyama, Hiroshi Kawazoe, Hiroya Matsumura, Shunsuke Tomomori, Michitaka Amioka, Yasuki Kihara
BACKGROUND: An animal experiment showed that long-term atrial pacing or persistent atrial fibrillation (AF) caused electrical remodeling of the atrioventricular (AV) node. We aimed to test the hypothesis that persistent AF decreases the AV conductivity in human hearts. METHODS AND RESULTS: We retrospectively compared the cardiac electrophysiological properties between patients with paroxysmal AF who underwent catheter ablation (PXAF, N = 254) and those with persistent or longstanding persistent AF (PSAF, N = 213)...
August 2016: Journal of Cardiovascular Electrophysiology
Marek Jastrzebski, Maciej Pitak, Andrzej Rudzinski, Danuta Czarnecka
No abstract text is available yet for this article.
September 2016: Journal of Cardiovascular Electrophysiology
Ying Yu, Linda Ye, Yi-Gang Li, Dean J Burkin, Dayue Darrel Duan
INTRODUCTION: Ischemia causes myocardial infarction and arrhythmias. Up-regulation of cardiac CLC-3 chloride channels is important for ischemic preconditioning-induced second-window protection against myocardial infarction. But its consequences in ischemia-induced electrical remodeling are still unknown. METHODS: The recently-characterized heart-specific overexpression of human short CLC-3 isoform (hsCLC-3(OE)) mice was used to study the effects of CLC-3 up-regulation on cardiac electrophysiology under ischemia/reperfusion conditions...
July 1, 2016: International Journal of Cardiology
Ashley M Nisbet, Patrizia Camelliti, Nicola L Walker, Francis L Burton, Stuart M Cobbe, Peter Kohl, Godfrey L Smith
Conduction abnormalities are frequently associated with cardiac disease, though the mechanisms underlying the commonly associated increases in PQ interval are not known. This study uses a chronic left ventricular (LV) apex myocardial infarction (MI) model in the rabbit to create significant left ventricular dysfunction (LVD) 8weeks post-MI. In vivo studies established that the PQ interval increases by approximately 7ms (10%) with no significant change in average heart rate. Optical mapping of isolated Langendorff perfused rabbit hearts recapitulated this result: time to earliest activation of the LV was increased by 14ms (16%) in the LVD group...
May 2016: Journal of Molecular and Cellular Cardiology
Chirag V Soni, Suresh C Tyagi, Nathan D Todnem, Srikanth Givvimani, Sathnur B Pushpakumar, Juan Villafane, Claudio Maldonado
Patients with hyperhomocysteinemia (HHcy), or elevated plasma homocysteine (Hcy), are at higher risk of developing arrhythmias and sudden cardiac death; however, the mechanisms are unknown. In this study, the effects of HHcy on sinus node function, atrioventricular conduction, and ventricular vulnerability were investigated by electrophysiological (EP) analysis, and the role of magnesium (Mg(2+)), an endogenous N-methyl-D-aspartate (NMDA) receptor antagonist, in attenuating EP changes due to HHcy was explored...
March 2016: Cell Biochemistry and Biophysics
William P Nelson
The atrioventricular (AV) bridge is vulnerable to many circumstances that depress conduction. Abnormal impulse transmission may be caused by drugs, autonomic effects, or destructive processes. Type 1 (Wenckebach) AV block is owing to depressed AV nodal conduction and is recognized by a prolonging PR interval ending in a "dropped beat." Type II (Mobitz) AV block is owing to abnormal infranodal conduction, and is usually accompanied by bundle branch block. Second-degree AV block with 2:1 conduction can be a difficult problem...
March 2016: Cardiac Electrophysiology Clinics
Isaac R Whitman, Nitish Badhwar
No abstract text is available yet for this article.
March 2016: JAMA Internal Medicine
Elena Ryzhii, Maxim Ryzhii
We study formation of second-degree atrioventricular blocks (Wenckebach and Mobitz types) with reduction of coupling between nodes in the heterogeneous oscillator model of cardiac conduction system. We demonstrate that maximal possible number of physiological mode lock patterns in both cases appears at a particular value of coupling coefficient. For the type II atrioventricular block total conduction ratio at high sinus rates might be represented by a product of conduction ratios of atrioventricular nodal and infrahisian blocks...
August 2015: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
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