Cardiac Arrhythmias

The most intimate mechanisms of cardiac arrhythmias are still quite unknown to scientists. Genetic studies on ionic alterations, the electrocardiographic features of cardiac rhythm and an arsenal of diagnostic tests have done more in the last five years than in all the history of cardiology. Similarly, therapy to prevent or cure such diseases is growing rapidly day by day. In this book the reader will be able to see with brighter light some of these intimate mechanisms of production, as well as cutting-edge therapies to date. Genetic studies, electrophysiological and electrocardiographyc features, ion channel alterations, heart diseases still unknown , and even the relationship between the psychic sphere and the heart have been exposed in this book. It deserves to be read

Advances in Electrocardiograms

Electrocardiograms have become one of the most important, and widely used medical tools for diagnosing diseases such as cardiac arrhythmias, conduction disorders, electrolyte imbalances, hypertension, coronary artery disease and myocardial infarction. This book reviews recent advancements in electrocardiography. The four sections of this volume, Cardiac Arrhythmias, Myocardial Infarction, Autonomic Dysregulation and Cardiotoxicology, provide comprehensive reviews of advancements in the clinical applications of electrocardiograms. This book is replete with diagrams, recordings, flow diagrams and algorithms which demonstrate the possible future direction for applying electrocardiography to evaluating the development and progression of cardiac diseases. The chapters in this book describe a number of unique features of electrocardiograms in adult and pediatric patient populations with predilections for cardiac arrhythmias and other electrical abnormalities associated with hypertension, coronary artery disease, myocardial infarction, sleep apnea syndromes, pericarditides, cardiomyopathies and cardiotoxicities, as well as innovative interpretations of electrocardiograms during exercise testing and electrical pacing

Does the small conductance Ca2+-activated K+ current (ISK) flow under physiological conditions in rabbit and human atrial isolated cardiomyocytes?

Background: Small conductance Ca2+-activated K+ current (ISK) may change cardiac atrial action potentials (AP) in response to altered [Ca2+]i; a potential therapeutic target for treating atrial fibrillation (AF). However, the contribution of ISK to atrial APs under physiological conditions is unclear. Furthermore, ISK may be enhanced in ventricles by heart failure, but whether by [Ca2+]i elevation in the non-failing ventricle is unknown. Aims: To test whether ISK flows under normal or increased global Ca2+]i, or with sub-sarcolemmal [Ca2+]i increase from APs in human and rabbit atrial cells. Also, to test an ISK blocker, ICAGEN (ICA), on rabbit left ventricular (LV) ion currents under [Ca2+]i elevation from Na+/Ca2+-exchanger (INa/Ca) stimulation. Methods: Myocytes were isolated enzymatically from hearts removed from anaesthetised rabbits, and from atrial tissues from consenting patients undergoing cardiac surgery. Whole-cell patch clamp (37°C) was used to record ion currents and APs (at 1, 2 or 3Hz), with [Ca2+]i measured using Fura-2. Results: A positive control tested stability/timing of K+ current (IK1) block: Ba2+(0.5 mM) significantly and reversibly decreased inward IK1 (at-115 mV) in 94% of LV cells, from -38.9±5.9 to -12.9±4.5 pA/pF (by 67%), and in 92% of atrial cells, by 43% (P0.05) at any [Ca2+]i, in rabbit or human (5-26 cells, 7-11 rabbits, 3-4 patients). APs recorded at 1 Hz (rabbit) were prolonged by 4-AP (ITO blocker; positive control): action potential depolarization at 30% repolarization (APD30) by 72%, at 70% repolarization (APD70) by 31%. By contrast, ICA (1 µM) had no effect on APD30-90, maximum diastolic potential (MDP), or Vmax, in human or rabbit. ICA at 10 µM (non-specific) increased APD70-90 vs time-matched controls. At 2 or 3 Hz, 1 µM ICA again had no effect on APs. In rabbit LV cells, stimulating INa/Ca increased [Ca2+]i (up to 2.8 µM) and inward /outward currents. ICA (1 µM) had no effect on [Ca2+]i or currents, whereas subsequent NiCl2 (10 mM; INa/Ca blocker) decreased them. By contrast, ICA 10 µM decreased outward (by 35%) and inward (49%) current, and [Ca2+]i (77%), with no effect of subsequent NiCl2. Conclusions: In rabbit and human atrial isolated myocytes, ISK may not flow under physiological conditions, nor during short bursts of supra-physiological stimulation, so atrial ISK activation (and thus its potential pharmacological inhibition during AF) may require changes to cellular electrophysiology or cell signalling systems to develop a sensitivity to ISK iii block. Furthermore, in non-failing LV myocytes, 1 µM ICA-sensitive ISK may not be activated by [Ca2+]i-elevation, and high ICA conc. may inhibit INa/Ca

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias