EP News, Basic and Translational April 5, 2012
Posted by Peng-Sheng Chen, MD, FHRS in Science & Research.Tags: Afib, Atrial fibrillation, Ventricular arrhythmia
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Circadian Variation of Ion Channel Expression
The susceptibility to ventricular arrhythmia or sudden death is determined by the duration (e.g. short or long QT syndromes and heart failure) or pattern (e.g. Brugada syndrome) of ventricular repolarization. It is also known that there is circadian variation of the susceptibility to ventricular arrhythmias. However, the molecular mechanism by which the body’s diurnal biological clock controls the circadian variations of repolarization remains unknown. (more…)
EP Science: Basic and Translational March 14, 2012
Posted by Peng-Sheng Chen, MD, FHRS in Science & Research.Tags: cardiomyopathy
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Truncation of Titin Causing Dilated Cardiomyopathy
Patients with dilated cardiomyopathy are at high risk of ventricular arrhythmia and sudden cardiac death. According to the Heart Rhythm Society Consensus Statement in Genetic Testing (Ackerman et al, Heart Rhythm 2011; 8:1308), none of the >25 known disease-associated genes has been shown to account for ≥5% of this disease.
A recent article by Herman et al (NEJM 2012; 366:619; PMID: 22335739) is likely to change that statement. The authors analyzed TTN (the gene encoding the sarcomere protein titin) in 312 subjects with dilated cardiomyopathy, 231 subjects with hypertrophic cardiomyopathy, and 249 controls. (more…)
EP Science and Research: Basic and Translational February 16, 2012
Posted by Peng-Sheng Chen, MD, FHRS in Science & Research.Tags: Arrhythmias, ICD, Implantable Cardioverter Defibrillator, sudden infant death syndrome
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Connexin and arrhythmias
Igarashi et al (Circulation 2012;125:216; PMID 22158756) randomized 30 Yorkshire swine into two groups (sinus rhythm and AF), and each group into three subgroups: sham-operated control, gene therapy with adenovirus expressing connexin (Cx) 40, and gene therapy with adenovirus expressing Cx43. The AF group had burst atrial pacing. All animals underwent terminal study seven days after gene transfer. Sinus rhythm animals had strong transgene expression but no atrial conduction changes. In AF animals, controls had reduced and lateralized Cx43 expression, and Cx43 gene transfer restored expression and cellular location to sinus rhythm control levels. In the AF group, both Cx40 and Cx43 gene transfer improved conduction and reduced AF relative to controls.
The authors conclude that Connexin gene therapy preserved atrial conduction and prevented AF. (more…)
EP News: Basic and Translational January 10, 2012
Posted by Peng-Sheng Chen, MD, FHRS in Science & Research.Tags: Arrhythmia, Atrial fibrillation, Genetic testing
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Genetic Testing as a Class I Indication for Patient Care
Gersh et al (Circulation 2011;13:124, PMID 22068435) updated the ACCF/AHA Guideline for the Diagnosis and treatment of Hypertrophic Cardiomyopathy (HCM).
In this updated recommendation for HCM, genetic testing is listed as a Class I recommendation to evaluate patients with HCM. All patients who undergo genetic testing should also undergo genetic counseling. Genetic screening is recommended in first-degree relatives of patients with HCM. In addition, genetic testing is recommended for patients with an atypical clinical presentation of HCM or when another genetic condition is suspected to be the cause. However, the Task Force also played down the importance of using specific mutations to predict the likelihood of sudden cardiac death (SCD). While some earlier works found certain mutations are “malignant,” subsequent studies showed in some instances the rate of adverse events (and prevalence of associated SCD risk markers) was lower in patients with “malignant” mutations than it was in those with mutations believed to be “benign.” (more…)
American Heart Association Meeting Report December 5, 2011
Posted by Peng-Sheng Chen, MD, FHRS in Science & Research.Tags: cardiac arrhythmia, Ventricular arrhythmia, Ventricular fibrillation
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Stellate Ganglionitis and Ventricular Arrhythmia
During the American Heart Association Annual Meeting, Rizzo et al (Circulation 2011:124:A13059) reported pathological characteristics of stellate ganglia resected from five long QT syndrome (LQTS) and five catecholaminergic polymorphic ventricular tachycardia (CPVT) patients. (more…)
EP News: Basic and Translational November 14, 2011
Posted by Peng-Sheng Chen, MD, FHRS in Science & Research.Tags: Cardiac electrophysiology, Research, Science
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Acetylcholine-Synthesizing T Cells Relay Neural Signals in a Vagus Nerve Circuit
Neural circuits regulate cytokine production to prevent potentially damaging inflammation. A prototypical vagus nerve circuit, the inflammatory reflex, inhibits tumor necrosis factor-α production in spleen by a mechanism requiring acetylcholine signaling through the α7 nicotinic acetylcholine receptor expressed on cytokine-producing macrophages. Nerve fibers in spleen lack the enzymatic machinery necessary for acetylcholine production; therefore, how does this neural circuit terminate in cholinergic signaling? (more…)
EP News: Basic and Translational October 6, 2011
Posted by Peng-Sheng Chen, MD, FHRS in Science & Research.Tags: Atrial fibrillation, Defibrillation, Heart Failure
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Defibrillation with High-Frequency Electric Field
Tandri et al (Sci Transl Med 2011;3:102ra96) studied the effects of electrical stimulation on conduction block in cardiac tissues. Electrical stimulation has been applied to nervous tissue to cause reversible conduction block, but has not been explored sufficiently in cardiac tissue.
The authors show that reversible propagation block can be achieved in cardiac tissue by holding myocardial cells in a refractory state for a designated period of time by applying a sustained sinusoidal high-frequency alternating current (HFAC). In doing so, reentrant arrhythmias are terminated.
EP News: Basic and Translational September 9, 2011
Posted by Peng-Sheng Chen, MD, FHRS in Science & Research.Tags: Arrhythmias, cardiomyopathy
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Genetic Variation in Titin in Arrhythmogenic Right Ventricular Cardiomyopathy
Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited genetic myocardial disease characterized by fibrofatty replacement of the myocardium and a predisposition to cardiac arrhythmias and sudden death.
Taylor et al (Circulation 2011; 124:876, PMID 21810661) evaluated the cardiomyopathy gene titin (TTN) as a candidate ARVC gene because of its proximity to an ARVC locus at position 2q32 and the connection of the titin protein to the transitional junction at intercalated disks. (more…)
August EP News: Basic and Translational August 8, 2011
Posted by Peng-Sheng Chen, MD, FHRS in Science & Research.Tags: AF, Arrhythmia, Clinical trials, Sodium channels
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Structure and function of sodium channels
Many voltage-gated ion channel (VGIC) superfamily members contain six-transmembrane segments in which the first four form a voltage-sensing domain (VSD) and the last two form the pore domain (PD).
Studies of potassium channels from the VGIC superfamily together with identification of voltage-sensor only proteins have suggested that the VSD and the PD can fold independently. Whether such transmembrane modularity is common to other VGIC superfamily members has remained untested. (more…)
EP News: Basic and Translational July 20, 2011
Posted by Peng-Sheng Chen, MD, FHRS in Science & Research.Tags: Afib, Arrhythmias, Atrial fibrillation, Long QT Syndrome, LQTS, Repolarization, Sex hormones
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Sex Hormones and Arrhythmia
Buber et al (Circulation 2011;123:2748, PMID 21632495) hypothesized that the hormonal changes associated with menopause may affect clinical risk in this population. The authors studied 282 LQT1 (n=151) and LQT2 (n=131) women enrolled in the Long-QT Syndrome Registry. (more…)
Heart Rhythm Society
Laurie Racenet, RN, MSN, ANP
Michael Giudici, MD, FACC, FACP, FHRS
Heather M. Ross, DNP, ANP-BC, CCDS, CEPS, FHRS
Anne Dubin, MD, FHRS
John D. Day, MD, FHRS
Andrea M. Russo, MD, FACC, FHRS
Joshua M. Cooper, MD, FACC
Amit J. Shanker, MD, FHRS, FACC
Bruce Stambler, MD
David Wiggins, RN, BS BME, CEPS
Fred M. Kusumoto, MD, FHRS
Leonard Ganz, MD, FHRS
christinechiuman
Craig Delaughter, MD, PhD
Ariana Del Negro, Heart Rhythm 2010 Quality
Peng-Sheng Chen, MD, FHRS
MSKremers MD,FHRS
Ann C. Garlitski, MD, FACC, FHRS
Alan Cheng, MD, FHRS
Ulrika Birgersdotter-Green, MD
Christopher Clyne, MD, FHRS
Kathleen Blake, MD, MPH, FHRS
David Scher, MD, FHRS
Sanjay Deshpande, MD, FHRS
Thomas F. Deering, MD, FHRS
