Cardiac Arrhythmias–New Considerations

Contributions of Ion Channels in Cardiac Arrhythmias (The Cardiac Ion Channels) Part 2

Cardiac sodium channelopathies To date, more than 150 mutations in SCN5A have been reported, the vast majority of them caused either LQTS3 and Brugada syndrome. Some patients with LQTS can be healing well whereas most of them may increase risk for sudden death due to ventricular tachyarrhythmias, in particular torsades de pointes. The character of […]

Contributions of Ion Channels in Cardiac Arrhythmias (The Cardiac Ion Channels) Part 3

Congenital cardiac arrhythmia LQTs is charactered by the prolongation of QT interval on ECG of the patients. Loss of function in Kv11.1 caused LQT2. Defective synthesis of mutations contained the premature termination codons is maybe the one fourths of all mutations of hERG channel (http: //www. fsm. it/cardmoc). Otherwise, hERG mutation of R534C display an […]

Contributions of Ion Channels in Cardiac Arrhythmias (The Cardiac Ion Channels) Part 4

Functions of Kir2 and Kir3 in heart To date, IK1, formed by coassembly of the Kir2.1.x subfamily of proteins (Kir 2.1, 2.2, and 2.3) In cardiac tissue, is the major component of inward rectifier potassium current and have a vital role in determinant of the resting membrane potential and conduces to the terminal phase of […]

L-Type Ca2+ Current in Cardiac Arrhythmias (The Cardiac Ion Channels) Part 1

Introduction Cardiac arrhythmias result from the confluence of structural and functional changes in the heart and genetic predisposition, reflecting an interaction between a susceptible substrate (e.g. an anatomically defined circuit, a myocardial scar, fibrosis or a monogenic arrhythmia syndrome) and a specific electrophysiological triggering event. Such triggered activities arises from delayed afterdepolarizations (DADs) or early […]

L-Type Ca2+ Current in Cardiac Arrhythmias (The Cardiac Ion Channels) Part 2

Role of ICaL in the cardiac arrythmogenesis associated to acquired pathophysiological states Myocardial ischemia and ventricular fibrillation Ventricular fibrillation (VF) and myocardial ischemia are inseparable. In general terms, myocardial ischemia is defined as disequilibrium between myocardial oxygen demand versus supply, which episodes can trigger serious and fatal arrhythmic events. Thus, in the clinical setting around […]

Natural Protection Against Cardiac Arrhythmias During Hibernation: Significance of Adenosine (Pathophysiology of Cardiac Arrhythmias) Part 1

Introduction Hibernation is a physiological adaptation to periods of seasonal resource limitation (Carey et al., 2003a; Drew et al., 2007). Hibernators undergo several bouts of torpor during a hibernation season. Torpor in hibernation is a period of profound bradycardia, tachycardia, metabolic suppression and decreased core body temperature (Drew et al. 2007). Hibernation is characterized by […]

Natural Protection Against Cardiac Arrhythmias During Hibernation: Significance of Adenosine (Pathophysiology of Cardiac Arrhythmias) Part 2

Anatomical peculiarity of hibernator’s heart An insight into the anatomy of a hibernator’s heart may provide clues as to how a hibernator can overcome heart failure under extreme hypothermia. The peculiar anatomy of the heart of a hibernator has been described by Walls in a hamster (Walls, 1942). Several interesting features of the conducting tissue […]

Neurohumoral Control of Heart Rate (Pathophysiology of Cardiac Arrhythmias) Part 1

Introduction It is well known that the heart generates and conducts electrical impulses, leading to a rhythmical contraction of the cardiac muscle. In normal situations, the atria contract about one sixth of a second ahead of ventricular contraction, allowing the filling of the ventricles before they pump the blood through the lungs and peripheral circulation. […]

Neurohumoral Control of Heart Rate (Pathophysiology of Cardiac Arrhythmias) Part 2

Cardiopulmonary reflex Despite the great importance of baroreflex in controlling arterial pressure, several investigations have demonstrated that the neural reflex of circulation also depends on cardiopulmonary reflex. Cardiopulmonary receptors are found in low pressure portions of the circulation, such as walls of the atria and pulmonary arteries. These mechano-sensitive receptors are activated by the distension […]

Neurohumoral Control of Heart Rate (Pathophysiology of Cardiac Arrhythmias) Part 3

Testosterone Testosterone, the major androgenic hormone is synthetized and released by the Leydig cells in the testis. It also gives rise to two other potent androgens: dihydrotestosterone and 5-alfa-androstenediol. Epidemiological and clinical studies indicate that testosterone status influence cardiovascular physiology and pathophysiology (Golden et al., 2002; Er et al., 2007). The effects of testosterone on […]

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